Method and system for introducing a catalyst precursor into heavy oil using a parallel mixer line and a bypass line

Abstract

A system and method for mixing a catalyst precursor into heavy oil includes parallel mixing lines configured to receive a diluted precursor mixture (a catalyst precursor pre-mixed with a hydrocarbon diluent) and mix it with heavy oil to form a conditioned feedstock. One of the mixing lines can be taken offline periodically (e.g., for maintenance), while one or more of the remaining mixing lines continue to form the conditioned feedstock. When one of the mixing lines goes offline, a bypass line maintains a substantially continuous flow volume of heavy oil. Valves and flow meters can be used to regulate the flow through the mixing lines and the bypass line. The system allows for periodic maintenance of the system without going completely offline, while enabling scale-up with virtually no limitations on the mixing process. By mixing the catalyst precursor into the heavy oil, colloidal-sized catalyst particles with high catalytic activity that promote beneficial upgrading reactions when the heavy oil is hydrotreated are formed in-situ.

Description

Technical Field

[0001] 1. Background Art of the Present Invention

[0001] The present invention relates to a method and system for mixing a catalyst precursor into a heavy oil feedstock prior to hydrotreating.

Background Art

[0002] 2. Related Art

[0002] Converting heavy oil into useful end products involves extensive processing such as reducing the boiling point of the heavy oil, increasing the hydrogen-to-carbon ratio, and removing impurities such as metals, sulfur, nitrogen, and coke precursors. Examples of hydrocracking processes for upgrading atmospheric tower bottoms and / or vacuum tower bottoms using conventional heterogeneous catalysts include fixed bed hydrotreating, fluid bed hydrotreating, and moving bed hydrotreating. Hydrocracking can also be performed using homogeneous catalysts in a slurry bed reactor. Non-catalytic upgrading processes for upgrading vacuum tower bottoms include thermal cracking such as delayed coking, flexicoking, visbreaking, and solvent extraction.

[0003]

[0003] The demand for more efficiently utilizing low-quality heavy oil feedstocks and obtaining valuable fuels therefrom is increasing. Low-quality feedstocks are characterized by containing a relatively large amount of hydrocarbons boiling above nominally 524 °C (975 °F). They also contain relatively high concentrations of asphaltenes, sulfur, nitrogen, and / or metals. The high-boiling fractions derived from these low-quality feedstocks typically have high molecular weights (often exhibiting higher densities and viscosities), and / or low hydrogen / carbon ratios, which are related to the presence of high concentrations of undesirable components including asphaltenes and carbon residues. Asphaltenes and carbon residues contribute to the formation of coke and deposits, making the processing difficult and usually causing fouling of conventional catalysts and hydroconversion units.

[0004]

[0004] Low-quality heavy oil feedstocks contain higher concentrations of asphaltenes, carbon residues, sulfur, nitrogen, and metals. Examples include heavy crude oil, oil sand bitumen, and residual oils remaining from conventional refining processes. Residuum (or "resid") may refer to atmospheric tower bottoms and vacuum tower bottoms. Atmospheric tower bottoms can have a boiling point of at least 343 °C (650 °F), but the cut point can vary between refineries and is understood to be as high as 380 °C (716 °F). Vacuum tower bottoms (also known as "resid pitch" or "vacuum residue") can have a boiling point of at least 524 °C (975 °F), but the cut point can vary between refineries and is understood to be as high as 538 °C (1000 °F), or even 565 °C (1050 °F).

[0005]

[0005] For comparison, Alberta light crude contains approximately 9 volume % of vacuum residue, while Lloydminster heavy oil contains approximately 41 volume % of vacuum residue, Cold Lake bitumen contains approximately 50 volume % of vacuum residue, and Athabasca bitumen contains approximately 51 volume % of vacuum residue. As a further comparison, relatively light oils such as Dansk Blend from the North Sea region contain only approximately 15% of vacuum residue, while lower-quality European oils such as Urals contain more than 30% of vacuum residue, and oils such as Arab Medium are even higher, containing approximately 40% of vacuum residue.

[0006]

[0006] In a given fluidized bed system, the production rate of the converted product is often limited by fouling. When attempts are made to increase the production of the converted product beyond a certain practical limit, the rate of fouling of the mixer, heat exchanger, strainer, and other processing equipment becomes too rapid, requiring more frequent shutdowns for maintenance and cleaning. Typically, refinery operators relate the observed rate of fouling of the equipment to the measured value of precipitate formation and reach an operating settling limit, beyond which the refinery will avoid operating the fluidized bed hydrocracker. Thus, precipitate formation and equipment fouling impose a practical upper limit on the conversion and the production rate of the converted product. Such problems are exacerbated when using lower quality heavy oil feedstocks.

[0007]

[0007] Fluidized bed reactors utilizing a dual catalyst system composed of a heterogeneous catalyst and a highly dispersed (e.g., colloidal or molecular) metal sulfide catalyst have been used to reduce equipment fouling and / or to enable an increase in the production rate of the converted product. The success or failure of the dual catalyst system depends on several variables, including the ability to disperse the catalyst precursor into the heavy oil without causing premature thermal decomposition of the catalyst precursor or allowing such thermal decomposition. If the catalyst precursor is not properly dispersed in the heavy oil prior to thermal decomposition, the dispersed metal sulfide catalyst particles formed in and obtained from the heavy oil feedstock will have low catalytic activity and can actually cause more equipment fouling, thereby negating its effectiveness.

[0008]

[0008] For example, U.S. Patent No. 5,372,705 to Bhattacharya ("Bhattacharya") discloses a dual catalyst system that includes a porous supported catalyst and an oil-soluble catalyst such as a metal salt of an aliphatic carboxylic acid. However, such a dual catalyst system actually causes more plugging and fouling of the apparatus, and Bhattacharya teaches that in order for the dual catalyst system to function properly and not increase fouling of the apparatus, relaxation by the use of 5-20 wt% of an aromatic heavy oil additive such as heavy cycle gas oil (HCGO) is required. As evidenced by the lack of a meaningful teaching regarding a mixing system that ensures complete mixing of the oil-soluble catalyst into the heavy oil feedstock, as a result of Bhattacharya's apparent failure to understand the importance of completely mixing the oil-soluble catalyst into the heavy oil feedstock prior to pyrolysis, the use of HCGO was required. Also, referring to it as a "catalyst" rather than a "catalyst precursor" suggests that pyrolysis was not considered a problem by Bhattacharya.

[0009]

[0009] U.S. Patent Application Publication No. 2005 / 0241991 A1 to Lott ("Lott") discloses a dual catalyst system that includes a porous supported catalyst and a colloidal or molecular catalyst that is formed in-situ within a heavy oil feedstock by appropriate mixing prior to pyrolysis using an oil-soluble catalyst precursor. Lott's examples achieved beneficial results using a colloidal or molecular molybdenum sulfide catalyst between 100-300 ppm. Lott teaches that the colloidal or molecular catalyst preferentially associates with asphaltene molecules that are difficult to hydrocrack using a porous supported catalyst because size exclusion prevents the diffusion of asphaltene molecules into the catalyst pores. Lott teaches that the association of the colloidal or molecular molybdenum sulfide catalyst with asphaltene molecules beneficially increases the conversion of asphaltene compared to using the porous supported catalyst alone.

[0010] Existing methods and systems for introducing a catalyst precursor into heavy oil may not be capable of being expanded to accommodate a larger hydrotreating reactor. Another problem is that mixing systems often require frequent maintenance to address issues such as blockage of static in-line mixers, solid accumulation in strainers, and seal leakage in high-shear mixers. During maintenance, the entire hydrotreating system must be shut down or, at least, operated using only heterogeneous catalysts without using dispersed metal sulfide catalysts.

[0011] Accordingly, there is a need to blend a catalyst precursor into heavy oil more efficiently and effectively to address existing problems that impede proper mixing. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEM

[0012] Disclosed herein are methods and systems for efficiently mixing a catalyst precursor into a heavy oil feedstock to form a conditioned feedstock in preparation for hydrotreating the heavy oil using one or more hydrotreating reactors. By mixing the catalyst precursor into the heavy oil feedstock, dispersed metal sulfide catalyst particles having high catalytic activity that promote beneficial upgrade reactions when the heavy oil is hydrotreated are formed in situ.

[0013]

[0013] When the method and system take one of the mixed lines offline for periodic cleaning and maintenance, etc., in order to substantially maintain a certain flow volume of the feedstock for the hydroprocessing reactor(s), a plurality of parallel mixed lines that can be scaled up for hydroprocessing reactors and bypass lines of virtually any size are used. In a preferred embodiment, the plurality of parallel mixers can be operated using a symmetric distribution of the heavy oil feedstock during normal operation. The bypass line is used to maintain the flow through each online mixer within its design capacity when another mixer goes offline for necessary maintenance. Further, the system of the present invention includes a flow control device that can be used to adjust the flow to the operating mixer(s) during maintenance, and a flow meter to ensure that the required flow is maintained by the remaining online mixed line(s) and bypass line(s).

[0014]

[0014] The system and method of the present disclosure enable the use of smaller, cost-effective and practically proven mixing devices, while ensuring that the injection of the dispersed catalyst precursor is maintained and a high level of processing performance is correspondingly sustained.

[0015]

[0015] An exemplary method of mixing a catalyst precursor into heavy oil is (1) blending a certain amount of the catalyst precursor with a certain amount of diluent to form a pre-diluted precursor mixture; (2) using a plurality of parallel mixed lines, each of which includes one or more mixers and at least one valve for adjusting (regulating) the flow of the mixed line, to mix the pre-diluted precursor mixture with the heavy oil feedstock to form a plurality of adjusted feedstock streams; (3) combining the adjusted feedstock streams in a common discharge line downstream from the parallel mixed lines to form a common adjusted feedstock stream. (4) Stopping the flow through the mixing line and causing or enabling a portion of the heavy oil feedstock to enter the bypass line, bypass the parallel mixing lines, and be combined with the common regulated feedstock stream in the common discharge line, and (5) While a portion of the heavy oil feedstock is passing through the bypass line, continuing to mix at least a portion of the diluent precursor mixture with the remaining portion of the heavy oil feedstock using at least one of the other parallel mixing lines.

[0016]

[0016] An exemplary system for mixing a catalyst precursor into heavy oil is (1) At least one mixer configured to receive an amount of catalyst precursor and blend it with an amount of diluent to form a diluent precursor mixture, (2) A plurality of parallel mixing lines configured to receive the diluent precursor mixture and mix it with the heavy oil feedstock to form a plurality of regulated feedstock streams, each parallel mixing line including one or more mixers and at least one valve for regulating the flow of the mixing line, (3) A common discharge line configured to receive and combine the regulated feedstock streams from the parallel mixing lines to form a common regulated feedstock stream, and (4) A bypass line configured to receive a portion of the heavy oil feedstock when the flow through at least one of the parallel mixing lines is closed and stopped, causing a portion of the heavy oil feedstock to bypass the parallel mixing lines, and combining the bypassed portion of the heavy oil feedstock with the common regulated feedstock stream in the common discharge line, (5) wherein the system is configured such that when one of the mixing lines is closed and a portion of the heavy oil feedstock passes through the bypass line, the remaining portion of the heavy feedstock is continuously mixed with the diluent precursor mixture by at least one of the other parallel mixing lines.

[0017]

[0017] The parallel mixing lines include two or more parallel mixing lines. In some embodiments, the method and system can include two, three, or four or more parallel mixing lines. In some embodiments, each mixing line includes a high-shear mixer and at least one other mixer such as, optionally, a static in-line mixer. One or more filters (e.g., at least one strainer) can typically be disposed along the mixing line upstream of the high-shear mixer. If desired, other filter filtration equipment and auxiliary devices known in the art may also be included in the mixing line. A premixer zone, such as one or more static in-line mixers, can be located in the heavy oil supply line upstream of where the parallel mixing lines divide.

[0018]

[0018] In some embodiments, the flow through the plurality of mixing lines can be controlled by one or more valves associated with each mixing line. For example, each mixing line can include a first valve upstream of the first mixer and a second valve downstream of the last mixer. Closing the valves allows the mixing line to be isolated, enabling maintenance and cleaning without pressurized hydrocarbon entering the mixing line from one or more other mixing lines.

[0019]

[0019] To divert a portion of the heavy oil feedstock into a bypass line, bypass the parallel mixing lines, and enter a common discharge line, one or more valves associated with the one or more operating parallel mixing lines and / or the common discharge line can be partially closed to restrict the flow, thereby reducing the pressure downstream of the valve(s) and increasing the pressure upstream of the valve(s). The pressure change caused by partially closing the valve(s) in the discharge line of one or more operating parallel mixing lines and / or the common discharge line increases the upstream pressure and causes a portion of the higher-pressure heavy oil feedstock upstream of the parallel mixing lines to pass through the bypass line. The bypass line may also include one or more valves that help control and adjust the amount and / or ratio of heavy oil flowing through the bypass line and the operating mixing line(s).

[0020]

[0020] In some embodiments, when one of the mixing lines is closed, an equal or similar amount of the pre-dilution precursor mixture can be mixed with the remaining amount of the heavy oil feedstock to maintain the same amount and / or rate of the catalyst precursor flowing through the system. In some embodiments, the flow of the heavy oil and the precursor mixture through one or more of the remaining operating mixing lines can be temporarily increased to account for the decrease in flow caused by the closing of one of the mixing lines. When one of the mixing lines is offline for maintenance, the mixing efficiency is somewhat reduced, but such an effect is minimal and is more than offset by the other benefits provided by the methods and systems of the invention disclosed herein. Closing one of a plurality of parallel mixing lines is far more preferable than stopping all mixing of the catalyst precursor into the heavy oil feedstock when performing regular maintenance on a mixing system that includes a single mixing line.

[0021]

[0021] To assist in regulating and balancing the flow rates through the parallel mixing lines, the common discharge line, and the bypass line, at least the common discharge line and the bypass line can include flow meters. Each of the parallel mixing lines can optionally include a flow meter for more accurate metering and control of the flow rates through the various lines of the mixing system. One or more valves of the system can be opened and / or closed to increase or decrease the flow rate of the material through the various lines in response to information obtained from the flow meters. The valves are configured to be adjusted manually and / or automatically to regulate and balance the flow rates.

[0022]

[0022] The hybrid system may further comprise a surge tank configured to receive a common regulated feedstock stream from a common discharge line and any heavy oil feedstock from a bypass line. The surge tank helps to equalize the flow of material through the hydrotreating system when there are fluctuations in the flow rate between the hybrid system and the hydrotreating reactor and other processing units downstream of the hybrid system. The surge tank also causes or enables additional diffusion and mixing of the catalyst precursor throughout the heavy oil feedstock before heating the regulated feedstock adjusted to thermally decompose the catalyst precursor and form in-situ dispersed metal sulfide catalyst particles within the heavy oil feedstock.

[0023]

[0023] In some embodiments, a portion of the heavy oil feedstock can be used as a diluent to form a diluent precursor mixture. In preferred embodiments, the heavy oil feedstock, when used as a diluent, is used in combination with one or more other hydrocarbon diluents (e.g., vacuum gas oil, atmospheric gas oil, decanted oil, or cycle oil) that remain fluid at a lower temperature to avoid premature decomposition of the catalyst precursor. The heavy oil feedstock or the feedstock diluent mixture can advantageously be passed through a heat exchanger prior to being mixed with the catalyst precursor to lower its temperature.

[0024]

[0024] In some embodiments, a portion of the regulated feedstock can be used as a diluent to form a diluent precursor mixture. In preferred embodiments, the regulated feedstock, when used as a diluent, is used in combination with one or more other hydrocarbon diluents that remain fluid at a lower temperature to avoid premature decomposition of the catalyst precursor. The regulated feedstock or the regulated feedstock diluent mixture can advantageously be passed through a heat exchanger prior to being mixed with the catalyst precursor to lower its temperature.

[0025]

[0025] Examples of suitable hydrocarbon diluents include, but are not limited to, vacuum gas oil (typically having a nominal boiling point range of 360-524 °C (680-975 °F)), decanted oil or cycle oil (typically having a nominal boiling point range of 360 °C - 550 °C (680-1022 °F)), and atmospheric gas oil (which typically has a nominal boiling point range of 200 °C - 360 °C (392-680 °F)), a portion of a heavy oil feedstock or a conditioned feedstock, and other hydrocarbons boiling at temperatures above about 200 °C.

[0026]

[0026] The catalyst precursor is preferably oil-soluble and has a decomposition temperature in the range of about 100 °C (212 °F) to about 350 °C (662 °F), or in the range of about 150 °C (302 °F) to about 300 °C (572 °F), or in the range of about 175 °C (347 °F) to about 250 °C (482 °F). Examples of catalyst precursors include organometallic complexes or compounds, more specifically, oil-soluble compounds or complexes of transition metals and organic acids having a decomposition temperature or range high enough to avoid substantial decomposition when mixed with a heavy oil feedstock under suitable mixing conditions. When mixing the catalyst precursor with a hydrocarbon oil diluent, it is advantageous to maintain the diluent below the temperature at which significant decomposition of the catalyst precursor occurs. One skilled in the art can select a mixing temperature profile that results in intimate mixing of the selected precursor composition without substantial decomposition prior to the in-situ formation of the dispersed metal sulfide catalyst particles.

[0027]

[0027] In some embodiments, a common conditioned feedstock stream can be passed through a heater to decompose at least a portion of the catalyst precursor and form in-situ dispersed metal sulfide catalyst particles within the heavy oil feedstock prior to entering the hydrotreating reactor. For example, the conditioned feedstock can be removed from a surge tank and passed through a heater. Alternatively or in addition, at least a portion of the conditioned feedstock can be heated within the hydrotreating reactor itself to decompose at least a portion of the catalyst precursor and form in-situ dispersed metal sulfide catalyst particles within the heavy oil feedstock. It has been found that preheating the conditioned feedstock upstream of the hydrotreating reactor provides a more active dispersed catalyst.

[0028]

[0028] In some embodiments, the dispersed metal sulfide catalyst particles have a size of less than 1 μm, or less than about 500 nm, or less than about 250 nm, or less than about 100 nm, or less than about 50 nm, or less than about 25 nm, or less than about 10 nm, or less than about 5 nm.

[0029]

[0029] In some embodiments, a heavy oil feedstock containing in-situ formed dispersed metal sulfide catalyst particles can be hydrotreated under hydrotreating conditions, where the dispersed metal sulfide catalyst particles promote beneficial hydrogenation and other upgrading reactions in the presence of heat and hydrogen. The hydrotreating can be carried out by one or more hydrotreating reactors selected from a slurry-phase reactor, a fluidized-bed reactor, and a fixed-bed reactor.

[0030]

[0030] For example, the hydrotreating of heavy oil can be carried out using one or more fluidized-bed reactors that utilize dispersed metal sulfide catalyst particles in combination with a heterogeneous fluidized-bed catalyst to produce upgraded heavy oil. Instead of or in addition to one or more fluidized-bed reactors, the hydrotreating of heavy oil can be carried out using one or more slurry-phase reactors that utilize dispersed metal sulfide catalyst particles as the sole catalyst or in combination with a conventional slurry catalyst, and / or one or more fixed-bed reactors that utilize dispersed metal sulfide catalyst particles in combination with a heterogeneous fixed-bed catalyst.

[0031]

[0031] After the hydrotreating of heavy oil, the upgraded heavy oil can be separated into one or more lower-boiling hydrocarbon fractions and one or more liquid hydrocarbon fractions. For example, the upgraded heavy oil can be separated using one or more high-temperature separation units, an interstage separator that induces a pressure drop, an atmospheric distillation column, or a vacuum distillation column.

[0032]

[0032] These and other advantages and features of the present invention will become more fully apparent from the following description and the appended claims, or may be learned by the practice of the invention as hereinafter described.

[0033]

[0033] To further clarify the above and other advantages and features of the present invention, a more specific description of the present invention is presented by referring to its specific embodiments shown in the accompanying drawings. It is understood that these drawings only show typical embodiments of the present invention and should not be regarded as limiting its scope. The present invention is described and explained using the accompanying drawings with additional specificity and detail.

Brief Description of the Drawings

[0034]

Figure 1

[0034] Shows a hypothetical molecular structure of asphaltene.

Figure 2

[0035] Schematically shows an exemplary ebullated bed hydrotreating system using a dual catalyst system that can be used for hydrotreating heavy oil.

Figure 3A

[0036] Figure 3A schematically shows an exemplary ebullated bed reactor and a separator unit for separating evaporable materials from non-evaporable materials.

Figure 3B

[0037] Figure 3B schematically shows an exemplary slurry-phase reactor and a separator unit for separating evaporable materials from non-evaporable materials.

Figure 3C

[0038] Figure 3C schematically shows an exemplary hydrotreating system including a slurry-phase reactor, a separator unit for separating evaporable materials from non-evaporable materials, and a fixed-bed reactor for further hydrotreating non-evaporable materials.

Figure 4A

[0039] Figure 4A schematically shows an exemplary ebullated bed hydrotreating system including a plurality of ebullated bed reactors and other processing devices.

Figure 4B

[0040] Figure 4B schematically shows an exemplary ebullated bed hydrotreating system including a plurality of ebullated bed reactors similar to those in Figure 4A and an inter-stage separator between two of the reactors.

Figure 5A

[0041] Figures 5A-5B schematically show an exemplary mixing system having two parallel mixing lines and a bypass line.

Figure 5B

Figure 6A

[0042] Figures 6A-6B schematically show an exemplary mixing system having three parallel mixing lines and a bypass line.

Figure 6B

Figure 7A

[0043] Figures 7A-7B schematically show an exemplary mixing system having four parallel mixing lines and a bypass line.

Figure 7B

[0035] I. Introduction

[0044] Disclosed herein are methods and systems for mixing a catalyst precursor into a heavy oil feedstock in preparation for hydrotreating the heavy oil. The mixing methods and systems of the present disclosure can be scaled up to accommodate different sized hydrotreating reactors and provide the ability to perform maintenance on the mixing lines without shutting down the entire mixing system. This is achieved by a plurality of parallel mixing lines and a bypass line that allows a mixing line to be closed and taken offline for maintenance while still providing a substantially constant flow of heavy oil to the system for hydrotreating.

[0036]

[0045] The mixing method and system of the present disclosure provide effective mixing of a dispersed catalyst precursor for a hydroconversion unit, such as a fluidized bed unit, a fixed bed unit, or a slurry reactor unit. The process is particularly suitable for use in large hydroconversion units that may be designed as a single row or multiple rows, but large-capacity hydroconversion units make it difficult to feed a dispersed catalyst precursor to a single mixing system. To address this difficulty, the inventive method and system include two or more parallel mixing lines, each equipped with a high-shear mixing device of conventional size and design.

[0037]

[0046] In addition to providing a high-capacity hydroconversion unit with means for using a conventional mixing device, the present invention has the further advantage of facilitating regular maintenance of the mixing device without interrupting the mixing of the catalyst precursor into the heavy oil feedstock. This is achieved by providing a bypass line to the mixing system, which allows a portion of the heavy oil feedstock to the hydroconversion unit to bypass the mixing system when the mixing line is taken offline for maintenance, and the remainder of the heavy oil feedstock is processed by the remaining online mixing line(s) without interrupting the mixing of the catalyst precursor into the heavy oil.

[0038]

[0047] As a further feature of the invention's mixing method and system, each parallel mixing line can be equipped with one or more flow control devices. A common discharge line that receives and combines the regulated feed streams from the individual mixing lines can also include a flow control device. The operation of one or more flow control devices can be advantageous or important to maintain an appropriate balance of flow between the remaining online mixing line(s) and the bypass line during maintenance periods. At least one flow control device is located downstream of the online high-shear mixer(s), for example, in each parallel mixing line and / or the common discharge line, and can be a manual valve, an automatic control valve, etc. During maintenance operations, one or more flow control devices are used to partially restrict the discharge flow from the online high-shear mixer(s), thereby causing or allowing a desired portion of the heavy oil feedstock to flow through the bypass line instead. Without such required flow control device(s), the online high-shear mixer(s) can generate sufficient positive discharge pressure such that the desired flow through the bypass line is not initiated or maintained, because the pressure in the common discharge line is higher than the pressure in the line(s) upstream of the parallel high-shear mixer(s) and in the bypass line.

[0039]

[0048] Further features of the invention's mixing method and system are the use of one or more flow measurement devices (flow meters) that can be used with one or more flow control devices (e.g., valves) to manage the flow through the entire mixing system. One aspect of flow control is provided by a flow measurement device and a flow control device installed in a common discharge line downstream of the parallel mixing lines, and flow control devices for the bypass line and optional flow measurement devices. Flow control can optionally include one or more alternative or additional flow measurement devices and / or valves for each of the mixing lines. Accurate and real-time flow measurement and control by measuring and adjusting the flow through the various lines maintains the desired flow rate through the various lines and the overall system, and provides important low-flow protection for the mixer.

[0040]

[0049] Additional features and advantages of the invention's mixing method and system are summarized in the following paragraphs.

[0050] The newer hydroconversion units can be very large, and it may be impractical to construct a single row of mixing devices for proper dispersion of the dispersed catalyst precursor blend in the heavy oil feedstock to accommodate such very large hydroconversion units. A mixing system having two or more parallel mixing lines facilitates the use of mixing devices of practical size as such larger hydroconversion units.

[0041]

[0051] For even a smaller hydrocracking unit where a single column mixing device may be practical, maintenance of the mixing device causes the entire off-line of the dispersed catalyst mixing system. This reduces the performance of the hydrocracking unit during the maintenance period. This is because there is no on-line backup for continuously mixing the catalyst precursor into the heavy oil. In addition to enabling maintenance of the mixing line while continuously producing the adjusted feedstock, the mixing system of the present disclosure enables the use of smaller capacity mixing lines rather than full-scale mixing lines that alternately and repeatedly perform the entire mixing process. In the case of full-scale mixing lines, one of the mixing lines remains idle and non-operational while the other mixing lines are operating, which is a waste of mixing resources.

[0042]

[0052] During normal operation of the parallel mixing lines, the system is preferably or preferably operated using a symmetric distribution of the feedstock flow (i.e., equal flow through each parallel mixing line). Advantageously or preferably, the parallel mixing lines are designed with symmetric piping and mixing devices such that the pressure drop is substantially equal through each parallel mixing line and an equal flow can be maintained between different mixing lines.

[0043]

[0053] When a mixing system having a simple arrangement of parallel mixing lines is used, problems occur when one of the parallel mixing lines goes off-line for maintenance while the operation of the other mixing line(s) continues. In this scenario, the remaining on-line mixing line(s) may not have sufficient capacity to accommodate the total heavy oil feed rate required by the hydrocracking unit. This may require a reduction in the heavy oil throughput by the hydrocracking unit during maintenance, which is undesirable as it correspondingly reduces the productivity of the unit.

[0044]

[0054] To address the above problems, the mixing method and system of the present invention include a bypass line. During the period when one of the parallel mixing lines is offline, the portion of the heavy oil feedstock that would otherwise pass through that mixing line can instead be diverted to the bypass line. This enables the total throughput of the heavy oil feedstock to be substantially maintained during maintenance. Advantageously or preferably, during the maintenance period, the flow of the heavy oil feedstock and the diluent precursor mixture is distributed to maximize the flow through the remaining online high-shear mixer(s) (consistent with the capacity limits of the mixer(s)), and the remainder of the heavy oil that exceeds the mixing capacity of the remaining online mixing line(s) takes a path through the bypass line.

[0045]

[0055] By maintaining the maximum possible feedstock flow through the remaining online mixing line(s) during the maintenance period, uninterrupted mixing of the catalyst precursor into a substantial portion of the heavy oil can be maintained. A sufficient amount of the dispersed catalyst precursor can continue to function properly during maintenance by temporarily rerouting a portion of the precursor that was injected through the mixing line that is offline for maintenance relative to the remaining online mixing line(s). If one of the mixing lines is offline for maintenance, the mixing efficiency may decrease somewhat, but such an effect is minimal and is outweighed by the other benefits provided by the method and system of the present invention disclosed herein.

[0046]

[0056] A problem that may be associated with the operation of the bypass line for favorable results is ensuring the desired distribution of the heavy oil feedstock flow when the mixing line goes offline for maintenance. As described, the preferred flow distribution is to maximize the flow through the remaining online mixing line(s), subject to their capacity limits, and route the remainder of the flow through the bypass line path. However, the operation of the high shear mixer is similar to that of a pump, and as a result, a higher pressure is generated in the discharge line (downstream of the high shear mixer) than in the suction line (upstream of the high shear mixer) due to the action of the mixer. When the bypass line is open and there are no one or more flow control devices, the pressure downstream of the remaining online high shear mixer(s) may be higher than the upstream pressure in the suction line, making it impossible to ensure forward flow of the feedstock through the bypass line. In fact, in the absence of one or more flow control devices or valves, the hydrocarbon flow may instead occur in the reverse direction of the bypass line, creating an undesirable circulation loop in the mixing system.

[0047]

[0057] To address the above problem and achieve favorable operation of the bypass line during the maintenance period, the methods and systems of the present disclosure include one or more flow control devices. These may be manual valves, automatic control valves, etc. Preferably, the flow control device is located in a common discharge line downstream of where the parallel mixing lines converge. Alternatively or in addition, the flow control device can be placed in each mixing line downstream of the high shear mixer. When the mixing line is offline for maintenance, the flow control device(s) in the common discharge line and / or the remaining online mixer(s) are adjusted to partially restrict the discharge flow from the online mixing line, changing the pressure profile in the mixing system. The pressure in the feedstock line upstream of the mixing line increases, thereby enabling the forward flow of the heavy oil feedstock to pass through the bypass line as desired. With appropriate adjustment of the flow control device(s), the desired distribution of flow between the remaining online mixing line(s) and the bypass line can be maintained.

[0048]

[0058] An additional optional feature of the present invention is the use of one or more flow measurement devices. Preferably, downstream of the high shear mixer and upstream of the point where the bypass line joins the common discharge line, there is a flow measurement device on the common discharge line and / or the parallel mixing line. This enables monitoring of the flow of heavy oil through the high shear mixer and ensures that the desired flow rate through the on-line high shear mixer is maintained both during normal operation and during maintenance operations.

[0049]

[0059] An optional flow meter may also be placed in the bypass line. Another optional feature of the present invention is a flow control device for the bypass line that provides flow distribution flexibility in combination with other flow control device(s).

[0050]

[0060] The mixing methods and systems of the present disclosure are further illustrated in FIGS. 5A-7B below. FIGS. 5A-5B illustrate an embodiment of a mixing system and method using two parallel mixing lines together with a bypass line. In some embodiments, the flow control device(s) may be valves and may be located on the common discharge line downstream of where the mixer discharge lines merge with each other, but upstream of the point where the bypass line merges with the common discharge line. The flow control valves are generally fully open during normal operation when both high-shear mixers are operating with a preferred symmetric distribution of flow. When one high-shear mixer is offline for maintenance, the flow control valves in the common discharge line and / or the remaining mixing lines downstream of the high-shear mixer are partially closed to restrict the flow in the remaining parallel mixing lines and / or the common discharge line and increase the upstream pressure. This causes or enables a desired portion of the heavy oil feedstock to flow through the bypass line, while still allowing a significant portion of the heavy oil feedstock to flow through the remaining online high-shear mixer, which can be increased during the maintenance period depending on the capacity of the mixer. FIG. 5A also illustrates a flow measurement device (flow meter) disposed on the common discharge line upstream of the flow control valve upstream of where the bypass line merges with the common discharge line. FIGS. 5A-5B also show optional flow measurement devices disposed on the bypass line and optional flow measurement devices disposed on the individual mixing lines.

[0051]

[0061] FIGS. 6A-6B illustrate an embodiment of a mixing system and method similar to the mixing system and method illustrated in FIGS. 5A-5B but including three parallel mixing lines. FIGS. 7A-7B illustrate an embodiment of a mixing system and method similar to the mixing system and method illustrated in FIGS. 5A-5B and FIGS. 6A-6B but including four parallel mixing lines.

[0052]

[0062] Before providing a more detailed description of the features illustrated in FIGS. 5A - 7B, which show exemplary mixing systems that can be used in the mixing methods of the present disclosure, first a reference is made to the intended definitions for certain terms, followed by a reference to FIGS. 1 - 4B and to existing hydroprocessing reactors and systems in which the mixing methods and systems of the present invention are used and / or integrated.

[0053] II. Definitions

[0063] The terms "asphaltene" and "asphaltenes" refer to substances in heavy oil feedstocks that are insoluble in paraffinic solvents such as propane, butane, pentane, hexane, and heptane. Asphaltenes can include sheets of condensed ring compounds held together by heteroatoms such as sulfur, nitrogen, oxygen, and metals. Broadly, asphaltenes include a wide range of complex compounds having from 80 to 1200 carbon atoms and, when determined by solution techniques, have molecular weights exclusively in the range of 1200 to 16,900. Approximately 80 - 90% of the metals in crude oil, which together with a high concentration of non - metallic heteroatoms make the asphaltene molecules in heavy oil resid more hydrophilic and less hydrophobic than other hydrocarbons, are contained in the asphaltene fraction.

[0054]

[0064] A hypothetical asphaltene molecular structure developed by A.G. Bridge of Chevron and collaborators is shown in FIG. 1. Asphaltenes are typically defined based on the results of insolubility analysis, and more than one of the definitions of asphaltenes may be used. Specifically, a commonly used definition of asphaltenes is the subtraction of toluene insolubles from heptane insolubles (i.e., asphaltenes are soluble in toluene, and precipitates and residues insoluble in toluene are not counted as asphaltenes). Asphaltenes defined in this manner may be referred to as "C 7 asphaltenes". Another definition is measured as the subtraction of toluene insolubles from pentane insolubles and is commonly referred to as "C 5 asphaltenes". In embodiments of the present invention, C 7Although an asphaltene definition is used, C 5 can be easily replaced with an asphaltene definition.

[0055]

[0065] "Fouling" refers to the formation of an undesirable phase (fouling substance) that interferes with the process. Fouling substances are usually carbonaceous materials or solids (e.g., precipitates) that accumulate and deposit within the processing equipment. Fouling of the equipment can result in shutdown of the equipment, production losses due to decreased equipment performance, increased energy consumption due to the insulating effect of fouling substance deposits in heat exchangers or heaters, increased maintenance costs for equipment cleaning, reduced fractionation efficiency, and reduced reactivity of heterogeneous catalysts. Hydroprocessing units, such as mixing lines, require periodic maintenance to remove precipitates and other fouling substances.

[0056]

[0066] The "rate of fouling of the equipment" in a hydrocracking reactor can be measured by at least one of: (i) the frequency of heat exchanger cleaning required, (ii) the frequency of switching to a spare heat exchanger, (iii) the frequency of filter replacement, (iv) the frequency of cleaning or replacement of strainers, (v) the rate of decrease in the surface temperature of the equipment, including within the equipment selected from heat exchangers, separators, or distillation columns, (vi) the rate of increase in the metal temperature of the furnace tubes, (vii) the rate of increase in the calculated fouling resistance factor of the heat exchanger and the furnace, (viii) the rate of increase in the differential pressure of the heat exchanger, (ix) the frequency of cleaning of the atmospheric distillation column and / or the vacuum distillation column, or (x) the frequency of periodic maintenance.

[0057]

[0067] "Heavy oil" and "heavy oil feedstock" refer to residual oils remaining from refinery processes such as heavy crude oil, oil sand bitumen, barrel bottoms, and visbreaker bottoms, and any other lower-quality materials that contain a significant amount of high-boiling hydrocarbon fractions and / or contain a significant amount of asphaltenes that can deactivate heterogeneous catalysts and / or cause or result in the formation of coke precursors and deposits. Examples of heavy oil include, but are not limited to, Lloydminster heavy oil, Cold Lake bitumen, Athabasca bitumen, atmospheric tower bottoms, vacuum tower bottoms, residual oil (or "residuum"), residuum pitch, vacuum residues (e.g., Urals VR, Arab Medium VR, Athabasca VR, Cold Lake VR, Maya VR, and Chichimene VR), deasphalted liquids obtained by asphaltenes by solvent deasphalting, asphaltene liquids obtained as by-products of deasphalting, and non-volatile liquid fractions remaining after distillation, thermal separation, solvent extraction, etc. of crude oil, bitumen from tar sands, liquefied coal, oil shale, or coal tar feedstock. As a further example, atmospheric tower bottoms (ATB) can have a nominal boiling point of at least 343°C (650°F), but the cut point can vary between refineries and is understood to be as high as 380°C (716°F). Vacuum tower bottoms can have a nominal boiling point of at least 524°C (975°F), but the cut point can vary between refineries and is understood to be as high as 538°C (1000°F) or even 565°C (1050°F).

[0058]

[0068] "Hydrocracking" and "hydroconversion" refer to processes whose main purpose is to reduce the boiling point range of heavy oil, with a substantial portion of the heavy oil being converted to a product having a boiling point range lower than that of the original feed. Hydrocracking or hydroconversion generally involves the fragmentation of larger hydrocarbon molecules into smaller molecular fragments having a smaller number of carbon atoms and a higher hydrogen-to-carbon ratio. The mechanism by which hydrocracking occurs typically involves the formation of hydrocarbon free radicals during thermal fragmentation, followed by capping of the free radicals with hydrogen. The hydrogen atoms or radicals that react with the hydrocarbon free radicals during hydrocracking can be generated at or by the active catalyst sites.

[0059]

[0069] The term "hydrotreating" refers to a process whose main purpose is to remove impurities such as sulfur, nitrogen, oxygen, halides, and trace metals from a feedstock and to saturate olefins and / or stabilize hydrocarbon free radicals by reacting them with hydrogen rather than reacting them with themselves. The main purpose is not to change the boiling point range of the feedstock. Hydrotreating is most often carried out using a fixed bed reactor, but other hydrotreating reactors can be used, examples of which are fluid bed hydrotreating reactors and slurry phase hydrotreating reactors.

[0060]

[0070] "Hydrocracking" and "hydroconversion" may also involve the removal of sulfur and nitrogen from the feedstock, as well as olefin saturation and other reactions typically associated with "hydrotreating". The terms "hydrotreating" and "hydroconversion" are intended to broadly refer to both the "hydrocracking" and "hydrotreating" processes that define both opposite ends of the spectrum and all points in between along the spectrum.

[0061]

[0071] The "hydrocracking reactor" refers to any vessel in which the hydrocracking of a feedstock (i.e., reduction of the boiling range) in the presence of hydrogen and a hydrocracking catalyst is the main purpose. The hydrocracking reactor is characterized by having one or more inlet ports into which heavy oil and hydrogen are introduced, an outlet port from which the upgraded feedstock or material is withdrawn, and sufficient thermal energy to promote the fragmentation of larger hydrocarbon molecules into smaller molecules and cause the formation of hydrocarbon free radicals. Examples of hydrocracking reactors include, but are not limited to, slurry-phase reactors (i.e., two-phase, gas-liquid systems), fluidized-bed reactors (i.e., three-phase, gas-liquid-solid systems), and fixed-bed reactors (i.e., a three-phase system containing a liquid feed that flows downward or upward through a fixed bed of a solid heterogeneous catalyst (typically hydrogen flows in parallel but may flow countercurrently in some cases), with the heavy oil).

[0062]

[0072] The "hydrocracking temperature" refers to the minimum temperature required to cause significant hydrocracking of the heavy oil feedstock. Generally, the hydrocracking temperature preferably falls within the range of about 399 °C (750 °F) to about 460 °C (860 °F), more preferably within the range of about 418 °C (785 °F) to about 443 °C (830 °F), and most preferably within the range of about 421 °C (790 °F) to about 440 °C (825 °F).

[0063]

[0073] The "gas-liquid slurry-phase hydrocracking reactor" refers to a hydrotreating reactor that includes a continuous liquid phase and a gas dispersion phase that forms a "slurry" with gas bubbles in the liquid phase. The liquid phase typically includes a hydrocarbon feedstock that may contain low-concentration dispersed metal sulfide catalyst particles and can behave colloidal or as a pseudo-solute, and the gas phase typically includes hydrogen gas, hydrogen sulfide, and vaporized low-boiling hydrocarbon products. The liquid phase can optionally include a hydrogen-donating solvent.

[0064]

[0074] When a solid catalyst is used with a liquid and a gas, the term "gas-liquid-solid, three-phase slurry hydrocracking reactor" is used. The gas may contain hydrogen, hydrogen sulfide, and vaporized low-boiling hydrocarbon products. The term "slurry-phase reactor" is intended to broadly refer to both types of reactors (e.g., those containing dispersed metal sulfide catalyst particles, those containing micrometer-sized or larger particulate catalysts, and those containing both).

[0065]

[0075] "Solid heterogeneous catalyst", "heterogeneous catalyst", and "supported catalyst" refer to catalysts typically used in fluidized bed and fixed bed hydrotreating systems, including catalysts basically designed for hydrocracking, hydroconversion, hydrodemetallization, and / or hydrotreating. A heterogeneous catalyst typically includes a catalyst support structure having a large surface area and interconnected channels or pores, and fine active catalyst particles such as sulfides of cobalt, nickel, tungsten, and / or molybdenum dispersed within the channels or pores. The pores of the support are typically of a limited size that maintains the mechanical integrity of the heterogeneous catalyst and prevents the destruction and formation of excessive particulates within the reactor. A heterogeneous catalyst can be manufactured as cylindrical pellets, cylindrical extrudates, other shapes such as trilobal, ring-shaped, saddleshaped, or as spherical solids.

[0066]

[0076] "Dispersed metal sulfide catalyst particles" and "dispersed catalyst" refer to catalyst particles having a particle size of less than 1 μm (submicron, or submicrometer), preferably less than about 500 nm, or less than about 250 nm, or less than about 100 nm, or less than about 50 nm, or less than about 25 nm, or less than about 10 nm, or less than about 5 nm. The term "dispersed metal sulfide catalyst particles" can include molecularly dispersed catalyst compounds or intramolecularly dispersed catalyst compounds. "Dispersed metal sulfide catalyst particles" typically exclude metal sulfide particles and aggregates of metal sulfide particles larger than 1 μm.

[0067]

[0077] "Intramolecularly dispersed catalyst" refers to a catalyst that is essentially "dissolved" in a hydrocarbon feedstock or a suitable diluent, or a catalyst compound that is dissociated from other catalyst compounds or molecules in a hydrocarbon feedstock or a suitable diluent. Very small catalyst particles containing several catalyst molecules (e.g., 15 molecules or less) bound together can be cited.

[0068]

[0078] "Residual dispersed catalyst particles" and "residual dispersed metal sulfide catalyst particles" refer to catalyst particles that remain with hydrocarbon products when transferred from one vessel to another (e.g., from a hydrotreating reactor to a separator and / or another hydrotreating reactor). Residual dispersed metal sulfide catalyst particles can also remain in the liquid residue fraction or pitch after separating hydrocarbon products into distillate and residue or pitch, such as by flash separation, thermal separation, atmospheric distillation, vacuum distillation, or vacuum stripping.

[0069]

[0079] "Adjusted feedstock" refers to a hydrocarbon feedstock that contains dispersed metal sulfide catalyst particles formed in situ within the feedstock during the decomposition of the catalyst precursor and the formation of the active catalyst as a result of the sufficient combination and mixing of the catalyst precursor. The adjusted feedstock includes adjusted heavy oil.

[0070]

[0080] "Upgrading", "upgrade", and "upgraded", when used to describe a hydrogenated or treated feedstock, or a resulting material or product, refer to one or more of the reduction of the molecular weight of the feedstock, the reduction of the boiling point range of the feedstock, the reduction of the asphaltene concentration, the reduction of the hydrocarbon free radical concentration, and / or the reduction of the amount of impurities such as sulfur, nitrogen, oxygen, halides, and metals.

[0071]

[0081] "Severity" refers to the amount of energy introduced into the heavy oil during the hydrogenation process and is related to the operating temperature of the hydrogenation reactor in combination with the duration or residence time (i.e., at the same or similar throughput, a higher temperature is related to a higher severity and a lower temperature is related to a lower severity). An increase in severity generally increases the amount of conversion products produced by the hydrogenation reactor, including both desirable and undesirable products. Conversion and throughput also affect severity. For example, when the temperature increases and the throughput is held constant, the conversion typically increases for a given feedstock. To maintain the temperature while increasing the throughput to shorten the residence time of the heavy oil in the reactor (i.e., increasing the liquid hourly space velocity), more thermal energy must be added to the system to offset the cooling effect of passing a larger amount of initially lower temperature heavy oil through the reactor per unit time.

[0072]

[0082] Desirable conversion products include hydrocarbons with reduced molecular weight, boiling point, and specific gravity, and examples of these include end products such as naphtha, diesel, jet fuel, kerosene, wax, fuel oil, etc. Other desirable conversion products include higher boiling point hydrocarbons that can be further processed using conventional purification and / or distillation processes. Bottom products of sufficient quality to be useful as fuel oil are another example of desirable conversion products.

[0073]

[0083] Undesirable conversion products include coke, precipitates, metals, and other solid materials, which can accumulate in the hydrotreating unit and cause fouling of internal components such as reactors, separators, filters, pipes, towers, heat exchangers, and heterogeneous catalysts. Undesirable conversion products also specifically may refer to unconverted residual oils that remain after distillation, such as atmospheric tower bottoms ("ATB") or vacuum tower bottoms ("VTB"), which are of too low quality to be useful for fuel oil or other desired uses. By minimizing undesirable conversion products, fouling of the unit and shutdowns required for unit cleaning are reduced. Nevertheless, an amount of unconverted residual oil may be desirable to provide a liquid transport medium for the carried coke, precipitates, metals, and other solid materials that can function properly in downstream separation units and / or can be transported by the residual oil that remains and can contaminate the unit.

[0074]

[0084] In addition to temperature, "severity" can be related to one or both of "conversion rate" and "throughput". Whether an increase in severity is accompanied by an increase in conversion rate and / or a change in throughput can depend on the quality of the heavy oil feedstock and / or the material balance of the overall hydrotreating system. For example, if it is desirable to convert a greater amount of feedstock and / or provide a greater amount of material to downstream units, an increase in severity may, essentially, be accompanied by an increase in throughput that does not necessarily involve an increase in the fraction conversion rate. This can be exemplified by the case where the residual oil fraction (ATB and / or VTB) is sold as fuel oil and the amount of this product is reduced by increasing the conversion rate without increasing the throughput. If it is desirable to increase the ratio of upgraded material to residual oil fraction, essentially, an increase in conversion rate that does not necessarily involve an increase in throughput may be desirable. If the quality of the heavy oil introduced into the hydrotreating reactor varies, it may be desirable to selectively increase or decrease one or both of the conversion rate and throughput to maintain the desired ratio of upgraded material to residual oil fraction and / or the desired absolute amount of the final product(s) produced.

[0075]

[0085] "Conversion rate" and "fraction conversion" often refer to the ratio expressed as the percentage of heavy oil converted to low-boiling substances and / or substances of lower molecular weight. The conversion rate is expressed as the percentage of the initial residue oil content (i.e., the components having a boiling point exceeding the defined residue cut point) converted to products having a boiling point below the defined cut point. The definition of the residue cut point can vary and can include nominal values such as 524 °C (975 °F), 538 °C (1000 °F), 565 °C (1050 °F), etc. This can be measured by distillation analysis of the feed stream and product stream that determines the concentration of components having a boiling point exceeding the defined cut point. The fraction conversion rate is expressed as (F - P) / F, where F is the amount of residue oil in the combined feed stream and P is the amount of residue oil in the combined product stream, and the residue oil content of both the feed and product is based on the same cut point definition. The amount of residue oil is often defined based on the mass of the components having a boiling point exceeding the defined cut point, but volume or molar definitions can also be used.

[0076]

[0086] The conversion rate of asphaltenes can differ from the overall conversion rate of heavy oil. For the purposes of this disclosure, a useful definition of the asphaltene conversion rate can be defined as follows, which results in a decimal fraction between 0 and 1 that can be converted to a percentage by multiplying by 100, based on the relative amounts of asphaltenes in the unused feedstock and the upgraded product. Conv = [Asph(unused feed) - Asph(product)] / Asph(unused feed) The asphaltene content of the recycle stream is internal to the process. If the conversion rate of asphaltenes is too low compared to the conversion rate of heavy oil as a whole, asphaltene recycle accumulation can occur.

[0077]

[0087] "Throughput" refers to the amount (mass or volume) of feedstock introduced into the hydrotreating reactor per unit time. Throughput can be expressed in volumetric terms such as barrels per hour or per day, or in mass terms such as metric tons per hour or per day. In normal usage, throughput is defined as the mass or volume feed rate of the heavy oil feedstock itself (e.g., vacuum tower bottoms, etc.). This definition usually excludes diluents or other components whose amounts can be added to or included in the overall feed to the hydroconversion unit, although a definition including those other components may also be used.

[0078]

[0088] "Space velocity" and "liquid space velocity" are related to the throughput of a particular reactor or reactor size and are normalized to remove the reactor size (volume). Thus, a larger reactor can have twice the throughput but still have the same space velocity as a reactor with half the volume size. Thus, an increase in space velocity typically scales with an increase in throughput for a given reactor size. Space velocity is inversely proportional to the residence time of the heavy oil in the reactor of a given reactor size.

[0079]

[0089] "Rate of production of the converted product" is an absolute rate that can be expressed in volumetric terms such as barrels per hour or per day, or in mass terms such as metric tons per hour or per day. The "rate of production of the converted product" should not be confused with yield or efficiency, which are sometimes erroneously called "rates" (e.g., rate of production per unit feed rate, or rate of production per unit of converted feed). The actual numerical values of both the initial rate of production of the converted product and the increase in the rate of production of the converted product are specific to an individual production facility and depend on the capabilities of that facility. Thus, it is useful to compare the production rates of the unit or facility in question before and after reforming, rather than for different units or facilities built with different capabilities.

[0080] III. Exemplary Hydrotreating System

[0090] Figures 2-4B illustrate exemplary hydrotreating reactors and systems that can be used and benefited from by being combined with or integrated into the mixing methods and systems of the present disclosure. The mixing methods and systems of the present disclosure can be used or disposed at any location within the illustrated hydrotreating system. Generally, the mixing system is typically disposed upstream of a hydrotreating reactor configured to operate using in-situ formed dispersed metal sulfide catalyst particles from a catalyst precursor in heavy oil. The methods and systems of the present disclosure provide for the continuous introduction of the catalyst precursor into the heavy oil and the in-situ formation of the dispersed metal sulfide catalyst particles therein, while sizing to accommodate different sized hydrotreating reactors and systems and facilitating the periodic maintenance of the mixing device without requiring shutdown of the overall mixing system.

[0081]

[0091] Feedstocks that can be hydrotreated using one or more hydrotreating reactors and that are used in the mixing methods and systems of the present disclosure include, but are not limited to, any desired fossil fuel feedstock and / or fractions thereof, including one or more heavy crude oils, oil sand bitumen, bottoms of barrel fractions from crude oil, atmospheric tower bottoms, vacuum tower bottoms, coal tar, liquefied coal, other residual oil fractions, pyrolysis oil, and deasphalted oil. Heavy oils and residual oils can include significant fractions of high boiling hydrocarbons (i.e., nominally 343 °C (650 °F) or higher, more specifically nominally 524 °C (975 °F) or higher) and / or asphaltenes. As mentioned above and illustrated in FIG. 1, asphaltenes are complex hydrocarbon molecules with a relatively low hydrogen to carbon ratio that results from a significant number of condensed aromatic and naphthene rings with paraffin side chains. Thin films consisting of condensed aromatic and naphthene rings are held together by heteroatoms such as sulfur or nitrogen, polymethylene crosslinks, thioether bonds, and / or vanadium and nickel complexes. Also, the asphaltene fraction contains compounds in which asphaltenes also have more sulfur and nitrogen than the remainder of the crude oil or vacuum residue and are also formed with a higher concentration of carbon (i.e., those that form coke precursors and precipitates).

[0082]

[0092] Figure 2 schematically shows an exemplary fluidized bed hydrotreating system 200 that utilizes a dual catalyst system of dispersed metal sulfide catalyst particles and a heterogeneous fluidized bed catalyst. The fluidized bed hydrotreating system 200 includes a fluidized bed reactor 230 and a separator 204 (e.g., a high-temperature separator, an inter-stage pressure differential separator, or a distillation column). The fluidized bed reactor 230 is similar to that used in the LC-Fining hydrocracking system developed by C-E Lummus. The catalyst precursor 202 is blended with a hydrocarbon diluent 204 in one or more premixers 206 to form a diluted precursor mixture 209. The diluted precursor mixture 209 is added to the heavy oil feedstock 208 and blended with the feedstock using a mixing system 210 (i.e., having a plurality of parallel mixing lines and bypass lines disclosed herein) to form an adjusted feedstock 211.

[0083]

[0093] The adjusted feedstock 211 is fed to a surge tank 212 having a pump-around loop 214 to achieve further mixing and dispersion of the catalyst precursor 202 within the feedstock 208. A bypass line (not shown) returns any heavy oil that bypasses a mixing line (not shown) to a common discharge line (not shown) and / or directly feeds heavy oil to the surge tank 212. The surge tank 212 and the pump-around loop 214 advantageously achieve further mixing of the catalyst precursor into the heavy oil, including heavy oil from the bypass line. The adjusted feedstock from the surge tank 212 is pressurized by one or more pumps 216, passes through a preheater 218, and is fed into the fluidized bed hydrotreating reactor 230 together with hydrogen gas 220 through one or more inlet ports 236 located at or near the bottom of the fluidized bed reactor 230.

[0084]

[0094] The fluidized bed reactor 230 includes a hydrocarbon material 226 and an expanded catalyst zone 242 that includes a heterogeneous catalyst 244 typical of fluidized bed reactors that is maintained in an expanded or fluidized state against gravity by the upward movement of the liquid hydrocarbon 226 and gas. A lower heterogeneous catalyst-free zone 248 is located below a distributor grid plate that defines the bottom of the expanded catalyst zone 242, and an upper heterogeneous catalyst-free zone 250 is located above the expanded catalyst zone 242. The dispersed metal sulfide catalyst particles 224 are dispersed throughout the hydrocarbon material 226 within the fluidized bed reactor 230 included in the expanded catalyst zone 242 and the heterogeneous catalyst-free zones 248, 250, thereby promoting beneficial upgrading reactions in the absence of the heterogeneous catalyst 244.

[0085]

[0095] The funnel-shaped reuse cup 256 that supplies to the reuse channel 252 connected to the fluidizing pump 254 continuously recirculates the hydrocarbon material 226 from the upper heterogeneous catalyst-free zone 250 to the lower heterogeneous catalyst-free zone 248. The downward suction by the reuse cup 256 at the upper part of the reuse channel 252 draws the hydrocarbon material 226 containing the dispersed catalyst particles 224 downward from the upper heterogeneous catalyst-free zone 250 through the reuse channel 252 to the bottom of the fluidized bed reactor 230 by the fluidizing pump 254. The recycled hydrocarbon material 226 is blended with a fresh feedstock containing dispersed metal sulfide catalyst particles (and / or catalyst precursors) and hydrogen gas 220.

[0086]

[0096] The unused heterogeneous catalyst 244 can be periodically introduced into the fluidized bed reactor 230 through the catalyst inlet pipe 258, and the spent heterogeneous catalyst 244 can be periodically withdrawn through the catalyst withdrawal pipe 260. The dispersed metal sulfide catalyst particles 224 provide additional catalytic activity within the expanded catalyst zone 242, the reuse channel 252, and the lower and upper heterogeneous catalyst-free zones 248, 250. The catalytic addition of hydrogen to the hydrocarbon outside the heterogeneous catalyst 244 reduces or minimizes the formation of deposits and coke precursors that often contribute to the inactivation of the heterogeneous catalyst and system fouling.

[0087]

[0097] The fluidized bed reactor 230 further includes an outlet port 238 from which the converted material 240 is drawn, at or near the top. The converted material 240 is introduced into a separator 204 that separates the volatile fraction 205 from the residue oil fraction 207. The volatile fraction 205 is drawn from the top of the high-temperature separator 204, and the residue oil fraction 207 is drawn from the bottom of the high-temperature separator 204. The residue oil fraction 207 contains residual metal sulfide catalyst particles schematically shown as catalyst particles 224. Optionally, at least a portion of the residue oil fraction 207 can be recycled back to the fluidized bed reactor 230 for reuse to form part of the feedstock and supply additional dispersed metal sulfide catalyst particles. Alternatively, the residue oil fraction 207 may be further processed using downstream processing units such as another fluidized bed reactor, a distillation column, a deasphalting unit, etc. In that case, the separator 404 may be a stage separator. A portion of the residue oil fraction 207 can be used as a diluent to form a catalyst precursor mixture.

[0088]

[0098] FIG. 3A schematically shows another type of fluidized bed hydrotreating reactor 310 having a different recycle system typical of the H-Oil hydrocracking system developed by Hydrocarbon Research, Inc. and currently licensed by Axens. The fluidized bed reactor 310 includes an inlet port 312 into which a heavy oil feedstock 314 and pressurized hydrogen gas 316 are introduced, and an outlet port 318 from which the upgraded hydrocarbon material 320 is drawn.

[0089]

[0099] The expanded catalyst zone 322 containing the heterogeneous catalyst 324 is defined by a distributor grid plate 326 that separates the expanded catalyst zone 322 from a lower catalyst-free zone 328 below the distributor grid plate 326, and an upper end 329 that defines an approximate boundary between the expanded catalyst zone 322 and an upper catalyst-free zone 330. The dotted boundary line 331 schematically indicates the approximate level of the heterogeneous catalyst 324 when not in an expanded or fluidized state. The dispersed metal sulfide catalyst particles 325 are dispersed throughout the hydrocarbon materials of both the fluidized bed reactor 310, the expanded catalyst zone 322, and the lower and upper heterogeneous catalyst-free zones 228, 230.

[0090]

[0100] The hydrocarbons and other materials in the fluidized bed reactor 310 are continuously recycled by a recycle channel 332 connected to a fluidizing pump 334 located outside the reactor 310. The materials are drawn from the upper heterogeneous catalyst-free zone 330 through a funnel-shaped recycle cup 336. The recycle cup 336 is helical in shape and serves to separate hydrogen bubbles from the recycled materials passing down the recycle channel 332, preventing cavitation of the fluidizing pump 334. The recycled materials enter the lower heterogeneous catalyst-free zone 328 through a discharge bell cap 343, where it is blended with the unused heavy oil feedstock 314 and hydrogen gas 316. This mixture passes upward through the distributor grid plate 326 and into the expanded catalyst zone 322. Unused heterogeneous catalyst can be periodically introduced into the expanded catalyst zone 322 through a catalyst inlet tube 336, and spent heterogeneous catalyst can be periodically withdrawn through a catalyst discharge tube 340.

[0091]

[0101] The main difference between the H-Oil fluidized bed reactor 310 shown in FIG. 3A and the LC-Fining fluidized bed reactor 200 shown in FIG. 2 is the location of the fluidizing pump. The fluidizing pump 334 within the H-Oil reactor 310 is located outside the reactor chamber. The recycled materials are introduced through a recycle port with a distributor cap 343 at the bottom of the fluidized bed reactor 310. The distributor cap 343 assists in evenly distributing the materials passing through the lower catalyst-free zone 328.

[0092]

[0102] The upgraded material 320 is withdrawn from the outlet port 318 of the fluidized bed reactor 310 and introduced into a separator 342 (e.g., a high-temperature separator, an inter-stage pressure differential separator, an atmospheric distillation column, or a vacuum distillation column). The separator 342 is configured to separate the volatile fraction (gas and distillate) 346 from the non-volatile fraction (or liquid) 348. The distillate and gas 346 are removed at one location (e.g., the top) of the separator 3342, and the non-volatile fraction 348 containing the liquid hydrocarbon and the residual dispersed metal sulfide catalyst particles is removed from another location (e.g., the bottom) of the separator 342.

[0093]

[0103] Figure 3B schematically represents a hydrotreating system 300 including a slurry-phase reactor 302 and a separator 304 (e.g., a high-temperature separator, an inter-stage pressure differential separator, or a distillation column). The heavy oil feedstock 306 is blended and conditioned with a catalyst precursor mixture 308 using a mixing system 310 (i.e., a plurality of parallel mixing lines and bypass lines disclosed herein). The mixing of the diluted precursor 308 includes a catalyst mixed with a diluent formed in a premixer (not shown). The conditioned feedstock from the mixing system 310 is pressurized by a pump 312, which can also serve as a multi-stage mixing device to further disperse the catalyst precursor throughout the entire heavy feedstock 306, passes through a preheater 314, and is supplied to the slurry-phase reactor 302 together with hydrogen gas 316 through one or more input ports 318 located at or near the bottom of the slurry-phase reactor 302.

[0094]

[0104] The agitator 320 at the bottom of the slurry reactor 302 induces mixing within the liquid phase, thereby helping to evenly disperse the heat generated by the hydrocracking reaction. Alternatively, or in addition to the agitator 320, the slurry reactor 302 may include recycle channels, recycle pumps, and a distributor grid plate (not shown) to promote a more uniform dispersion of reactants, catalyst, and heat, as in a conventional ebullated bed reactor (see FIGS. 2 and 3A). Hydrogen is schematically represented as gas bubbles 322, and the dispersed metal sulfide catalyst particles are schematically represented as catalyst particles 324 within the reactor 302. It is understood that the gas bubbles 322 and catalyst particles 324 are shown oversized for viewing in the drawing; in reality, they cannot be seen with the naked eye.

[0095]

[0105] The heavy oil feedstock 306 is catalytically upgraded in the slurry reactor 302 in the presence of hydrogen 316 and the dispersed metal sulfide catalyst 324 to form an upgraded hydrocarbon product 326. The upgraded product 326 is continuously withdrawn from the slurry reactor 302 through an output port 328 located at or near the top of the reactor 302 and then optionally passed through optional hydrotreating equipment 330 before being fed to a separator 304 (e.g., a high-temperature separator and / or a distillation column). The upgraded product 326 fed to the separator 304 contains residual catalyst particles schematically represented as particles 324' and residual hydrogen schematically represented as bubbles 322', which can continue to promote the beneficial upgrading reaction and reduce fouling of the apparatus. The separator 304 separates the volatile fraction 305 from the non-volatile fraction 307. The volatile fraction 305 is withdrawn from the top of the high-temperature separator 304, and the non-volatile fraction 307 is withdrawn from the bottom of the high-temperature separator 304.

[0096]

[0106] Figure 3C schematically depicts a hydrotreating system 300 that includes a slurry-phase reactor 302, a high-temperature separator 304, and a fixed-bed reactor 360. The upgraded hydrocarbon material 326 contains residual dispersed metal sulfide catalyst particles schematically represented as particles 324' within the high-temperature separator 304. The liquid fraction 307 and the residual dispersed metal sulfide catalyst particles 324' from the high-temperature separator 304 are introduced into the fixed-bed reactor 360 for further hydrotreating. The fixed-bed reactor 360 may be designed to perform hydrocracking and / or hydrotreating reactions depending on the operating temperature and / or the type of solid-supported catalyst used within the fixed-bed reactor 360.

[0097]

[0107] More specifically, the fixed-bed reactor 360 includes an input port 362 through which the liquid fraction 307 and make-up hydrogen gas 364 are introduced at the top, and an output port 366 through which the further hydrotreated material 368 is withdrawn at the bottom. The fixed-bed reactor 360 further includes a plurality of vertically stacked and spaced catalyst beds 370 that contain packed porous supported catalyst. Above each catalyst bed 370, there is a distributor grid 372 that helps to more uniformly distribute the flow of feedstock passing downward through the catalyst bed 370. Catalyst-free zones 374 exist above and below each catalyst bed 370. The residual catalyst particles 324' continue to be dispersed throughout the feedstock within the fixed-bed reactor 360 in both the catalyst beds 370 and the catalyst-free zones 374, further promoting beneficial upgrading reactions. Auxiliary ports 376 may be provided at the center and / or bottom of the fixed-bed reactor 360 into which cooling oil and / or hydrogen quench can be introduced to cool the heat generated by the hydrotreating reaction and control the reaction rate, thereby helping to prevent the formation of coke precursors and deposits and / or excess gas within the fixed-bed reactor 360.

[0098]

[0108] Figure 4A schematically shows a fluidized bed hydrotreating system 400 comprising a plurality of fluidized bed reactors 410. An example of the hydrotreating system 400 is an LC-Fining or H-Oil hydrotreating unit, and may include three fluidized bed reactors 410a, 410b, 410c in series to upgrade a feedstock 412. The feedstock 412 from the surge tank 414 is pressurized, preheated, and introduced into the first fluidized bed reactor 410a together with hydrogen gas 416, and both pass through their respective heaters before entering the first reactor 410a. The upgraded hydrocarbon material 420a from the first fluidized bed reactor 410a is introduced into the second fluidized bed reactor 410b together with additional hydrogen gas 416. The upgraded hydrocarbon material 420b from the second fluidized bed reactor 410b is introduced into the third fluidized bed reactor 410c together with additional hydrogen gas 416.

[0099]

[0109] One or more inter-stage separators (not shown) may optionally be interposed between the first and second fluidized bed reactors 410a and 410b, and / or between the second and third fluidized bed reactors 410b and 410c to remove lower boiling fractions and gases from the non-volatile fraction containing liquid hydrocarbons and residual dispersed metal sulfide catalyst particles. It should be understood that it may be desirable to remove lower alkanes such as hexane and heptane, which are poor solvents for asphaltenes but beneficial fuel products. Removal of volatile materials between the plurality of reactors improves the production of the upgraded product and increases the solubility of asphaltenes in the liquid hydrocarbon material fed to the downstream reactor(s). Both improve the efficiency of the overall hydrotreating system.

[0100]

[0110] The upgraded hydrocarbon material 420c from the third fluidized bed reactor 410c is sent to a high-temperature separator 442a that separates a volatile fraction and a non-volatile fraction. The volatile fraction 446a passes through a heat exchanger 450 that removes heat that can be used to preheat the hydrogen gas 416 before being supplied to the first fluidized bed reactor 410a. The somewhat cooled volatile fraction 446a is sent to an intermediate-temperature separator 442b where the remaining volatile fraction 446b is separated from a liquid fraction 448b that can result from the cooling by the heat exchanger 450. The remaining volatile fraction 446b is sent to a downstream low-temperature separator 442c for further separation into a gas fraction 452c and a degassed liquid fraction 448c.

[0101]

[0111] The liquid fraction 448a from the high-temperature separator 442a is combined with the liquid fraction 448b resulting from the intermediate-temperature separator 442b, sent to a low-pressure separator 442d to separate a hydrogen-rich gas 452d from the degassed liquid fraction 448d, and sent to a backend system 460 that includes one or more distillation towers including a vacuum distillation tower together with the degassed liquid fraction 448c from the low-temperature separator 442c, and the material is fractionated into products.

[0102]

[0112] The gas fraction 452c from the low-temperature separator 442c is purified into offgas, purge gas, and hydrogen gas 416. The hydrogen gas 416 is compressed, mixed with makeup hydrogen gas 416a, passed through the heat exchanger 450, and introduced into the first fluidized bed reactor 410a together with the feedstock 414, or directly introduced into the second and third fluidized bed reactors 410b and 410c.

[0103]

[0113] FIG. 4B schematically shows a fluidized bed hydrotreating system 400 with a plurality of fluidized bed reactors, similar to the system shown in FIG. 4A, but showing an inter-stage separator 421 interposed between the second and third fluidized reactors 410b and 410c (although the inter-stage separator 421 (or other separator) may be interposed between the first and second fluidized reactors 410a and 410b). As shown, the effluent from the second stage fluidized reactor 410b enters an inter-stage separator 421 which can be a high pressure high temperature separator. The liquid fraction from the separator 421 is combined with a portion of the recycled hydrogen from line 416 and fed to the third stage reactor 410c. The vapor fraction from the inter-stage separator 421 bypasses the third stage reactor 410c, is mixed with the effluent from the third stage reactor 410c, and then enters the high pressure high temperature separator 442a.

[0104]

[0114] Thereby, the lighter, more saturated components formed in the first two reactor stages 410a, 410b can bypass the third stage reactor 410c. This advantage is (1) a reduction in the vapor load on the third stage reactor 410c, which increases the volumetric utilization of the third stage reactor for converting the remaining heavy components, and (2) a reduction in the concentration of the “inverse solvent” components (saturates), which can destabilize (e.g., precipitate) the asphaltenes in the third stage reactor 410c.

[0105]

[0115] The hydrotreating system is typically configured and operated to promote more severe hydrocracking reactions rather than less severe hydrotreating reactions such as hydrotreating. Hydrocracking involves the reduction of the molecular weight of larger hydrocarbon molecules and / or the breaking of carbon-carbon molecular bonds such as the ring opening of aromatic compounds. On the other hand, hydrotreating mainly involves the hydrogenation of unsaturated hydrocarbons where the breaking of carbon-carbon molecular bonds is minimal or not at all.

[0106]

[0116] To promote more severe hydrocracking than a less severe hydrotreating reaction, the hydrotreating reactor(s) is preferably operated at a temperature in the range of about 750°F (399°C) to about 860°F (460°C), more preferably in the range of about 780°F (416°C) to about 830°F (443°C), and preferably at a pressure in the range of about 1000 psig (6.9 MPa) to about 3000 psig (20.7 MPa), more preferably in the range of about 1500 psig (10.3 MPa) to about 2500 psig (17.2 MPa), and preferably for 0.05 hour -1 to about 0.45 hour -1 in the range, more preferably about 0.1 hour -1 to about 0.35 hour -1 at a liquid hourly space velocity. The difference between hydrocracking and hydrotreating can also be expressed in terms of the residual oil conversion rate (hydrocracking results in a substantial conversion of higher boiling hydrocarbons to lower boiling hydrocarbons, while hydrotreating does not).

[0107]

[0117] The hydrotreating system disclosed herein can achieve a total residual oil conversion rate in the range of about 60% to about 95%, preferably in the range of about 75% to about 90%. The preferred conversion rate range typically depends on the type of feedstock, as the processing difficulty varies between different feedstocks.

[0108]

[0118] Operating a fluidized bed reactor using a dual catalyst system can result in the same or reduced fouling of the apparatus compared to operating a fluidized bed reactor using only a heterogeneous catalyst. For example, when using a dual catalyst system instead of a heterogeneous catalyst alone, the rate of fouling of the apparatus can result in one or more of the following benefits: (i) reduced frequency of heat exchanger shutdown and / or distillation column shutdown for cleaning, (ii) reduced frequency of filter and strainer replacement or cleaning, (iii) reduced frequency of switching to a spare heat exchanger, (iv) reduced rate of decrease in the surface temperature of the apparatus such as a heat exchanger, separator, or distillation column, (v) reduced rate of increase in the metal temperature of the furnace tubes, and (vi) reduced rate of increase in the calculated fouling resistance factor of the heat exchanger.

[0109] IV. Hybrid Systems and Methods

[0119] Figures 5A - 7B illustrate exemplary hybrid systems and corresponding methods for producing a well - mixed and conditioned heavy oil feedstock. Figures 5A - 5B illustrate an exemplary hybrid system 500 having two parallel mixing lines. Figures 6A - 6B illustrate an exemplary hybrid system 600 having three parallel mixing lines. Figures 7A - 7B illustrate an exemplary hybrid system 700 having four parallel mixing lines. It is understood that Figures 5A - 7B are merely illustrative of hybrid systems within the meaning and scope of the present disclosure. The hybrid system may be modified as desired without departing from the spirit of the invention, for example, to include additional mixing lines and / or other processing devices.

[0110]

[0120] Figures 5A - 5B more specifically illustrate a hybrid system 500 configured to mix a heavy oil feedstock 502 with a diluent precursor mixture 508. The diluent precursor mixture 508 is formed by mixing a catalyst precursor 504 (e.g., an oil - soluble catalyst precursor) with a diluent 506 using one or more mixers known in the art, such as one or more in - line static mixers and / or one or more high - shear mixers. The heavy oil feedstock 502 and the diluent precursor mixture 508 are supplied to a common supply line 510 and divided into first and second parallel mixing lines 512a, 512b.

[0111]

[0121] The heavy oil feedstock sidestream 536 can optionally be used as a diluent to make the diluent precursor mixture 508. A cooler 538 is used to lower the temperature of the heavy oil feedstock sidestream 536 to prevent premature thermal decomposition of the catalyst precursor 504 in the diluent precursor mixture 508 before it is fully mixed with the heavy oil feedstock 502.

[0112]

[0122] Each of the mixing lines 512a, 512b may include upstream valves 514a, 514b, which can be selectively opened during operation of the mixing lines 512a, 512b and closed to take the mixing line 512 offline for maintenance and cleaning. When online, the upstream valves 514a, 514b are open to allow split flows of the heavy oil feedstock 502 and the pre-diluent mixture 508 to flow through the first and second mixing lines 512a, 512b. In a preferred embodiment, the first and second parallel mixing lines 512a, 512b are designed using symmetric piping and mixing devices such that the pressure drop is substantially equal through each parallel mixing line 512 and an equivalent flow can be maintained between different mixing lines 512. Nevertheless, different capacity and flow mixing lines 512 can be used, for example, when retrofitting a single row of mixing lines to include one or more additional mixing lines.

[0113]

[0123] In the mixing system 500 shown in FIG. 5A, split flows of the heavy oil feedstock 502 and the pre-diluent mixture 508 pass through the first and second static in-line mixers 516a, 516b for initial mixing to produce first and second initial mixed flows, and then pass through the first and second strainers 518a, 518b to remove any unwanted solids in the initial mixed flows. The first and second mixed flows are then supplied to the first and second high-shear mixers 520a, 520b to provide first and second conditioned feedstock flows. Optional first and second flow meters 522a, 522b can be provided to measure the flow through the first and second mixing lines 512a, 512b downstream of the first and second high-shear mixers 520a, 520b.

[0114]

[0124] FIG. 5B is similar to FIG. 5A, except that a common static in-line mixer 516 is located in the common supply line 510 and functions as a premixer upstream of the point where the first and second parallel mixing lines 512a and 512b branch, and the individual static in-line mixers 516a, 516b of the mixing lines 512a and 512b are omitted.

[0115]

[0125] The first and second flow control devices 524a, 524b are each located downstream of the high shear mixers 520a, 520b. The flow control devices 524a, 524b can provide multifaceted functions. When both the first and second parallel mixing lines 512a, 512b are on-line, the flow control devices 524a, 524b are open. When one of the mixing lines 512 is taken off-line, the corresponding flow control device 524 can be closed to prevent the backflow of the pressurized and adjusted feedstock from the other mixing line 512 still in operation. The flow control device 524 of the mixing line 512 still in operation can be open all the way through, or alternatively, can be partially closed to restrict the flow and increase the upstream pressure, allowing some of the heavy oil feedstock 502 to enter the bypass line 540 or making it possible.

[0116]

[0126] The adjusted feedstock flows from the first and second mixing lines 512a, 512b are supplied to a common discharge line 525 and combined to form a common adjusted feedstock flow 546. The common adjusted feedstock flow 546 passes through a common flow measurement device 528 (e.g., a flow meter) and then through a common flow control device 526 (e.g., a valve), where it is remixed with any heavy oil feedstock from the bypass line 540 and then enters the surge tank 530.

[0117]

[0127] The adjusted feedstock side stream 532 from the surge tank 530 can optionally be used as a diluent to make the dilution precursor mixture 508. The cooler 534 is used to lower the temperature of the adjusted feedstock side stream 532 to prevent premature thermal decomposition of the catalyst precursor 504 in the dilution precursor mixture 508 before it is fully mixed with the heavy oil feedstock 502.

[0118]

[0128] When both of the parallel mixing lines 512a and 512b are operating online, the common flow control device 526 is open. When one of the mixing lines 512a, 512b is closed and taken offline, the common flow control device 526 partially closes to restrict the flow of material through the common discharge line 525, increasing the upstream pressure to cause or enable a portion of the heavy oil feedstock to enter the bypass line 540. The common flow control device 526 can be used alone or in combination with one of the flow control devices 524 corresponding to the mixing line 512 that is still in operation.

[0119]

[0129] The bypass line 540 typically does not have the heavy oil feedstock 502 flowing through it when both the first and second mixing lines 512a, 512b are operating online. However, when one of the parallel mixing lines 512 is closed and taken offline, a portion of the heavy oil feedstock 502 that is not supplied to the remaining online mixing line 512 causes or enables the passage through the bypass line 540 to maintain the throughput of the heavy oil feedstock 502 through the mixing system 500. As discussed above, the flow of the heavy oil feedstock 502 through the bypass line 540 is caused or induced by restricting the flow through the common discharge line 525, partially closing the common flow control valve 526 and / or the mixing line valve 524 of the operating mixing line 512. This induces a pressure drop and increases the upstream pressure sufficient to cause a portion of the heavy oil feedstock 502 to enter the bypass line 540. An optional flow meter 542 in the bypass line 540 measures the flow rate of the heavy oil feedstock 502 passing through the bypass line 540. The bypass line 540 is joined to the common discharge line 525 to combine the heavy oil feedstock 508 from the bypass line with the common regulated feedstock stream 546 downstream of the flow control device 526 and the flow meter 528.

[0120]

[0130] The flow rates of the split heavy oil feedstock streams passing through the remaining operating mixing line 512 and the bypass line 540 can each be measured by a common flow meter 528 and optionally a bypass flow meter 542. The respective flow rates of the materials passing through the remaining operating mixing line 512 and the bypass line 540 can be adjusted by adjusting against a common flow control valve 526 and / or a bypass line valve 544. By measuring the flow rate using a flow meter and performing the adjustment using a flow control device, the desired balance of the flow through the various lines can be achieved and maintained. In addition to adjusting the flow rate through the bypass line 540, when the first and second mixing lines 512a, 512b are open and operating, the bypass line valve 544 can be closed or partially restricted to balance the line pressure to ensure that the heavy oil feedstock 502 does not pass through the bypass line 540 in either the forward or reverse direction.

[0121]

[0131] An exemplary method of mixing a catalyst precursor into heavy oil includes using the mixing system 500 illustrated in FIG. 5A, (1) blending an amount of catalyst precursor 504 with an amount of diluent 506 to form a pre-dilution precursor mixture 508, (2) using a plurality of parallel mixing lines 512, each parallel mixing line 512 including one or more mixers 516, 520 and at least one valve 514, 524 for adjusting the flow of the mixing line 512, to mix the pre-dilution precursor mixture 508 with the heavy oil feedstock 502 to form a plurality of adjusted feedstock streams, (3) combining the adjusted feedstock streams in a common discharge line 525 downstream of the parallel mixing lines 512 to form a common adjusted feedstock stream 546, (4) stopping the flow through the mixing line 512 and causing or allowing a portion of the heavy oil feedstock 502 to enter the bypass line 540, bypass the parallel mixing lines 512, and combine with the common adjusted feedstock stream 546 in the common discharge line 525, and While a portion of the heavy oil feedstock 502 passes through the bypass line 540, continuing to mix at least a portion of the diluted precursor mixture 508 with the remaining portion of the heavy oil feedstock 502 using at least one other of the parallel mixing lines 512.

[0122]

[0132] When using the alternative mixing system 500 illustrated in FIG. 5B, the method optionally includes premixing the diluted precursor mixture 508 with the heavy oil feedstock 502 using a common static in-line mixer 516 upstream of where the first and second mixing lines 512a, 512b branch. The method also omits mixing the diluted precursor mixture 508 with the heavy oil feedstock 502 using the static in-line mixers 516a, 516b of the first and second mixing lines 512a, 512b illustrated in FIG. 5A.

[0123]

[0133] By way of illustration and not limitation, a typical hydrotreating system may require a heavy oil flow rate of 100 to 300 tons per hour. When operating both the first and second parallel mixing lines 512a, 512b, it may be advantageous or preferable to divide the heavy oil feedstock 502 equally such that there is a symmetric (e.g., equal) flow of material through each of the first and second parallel mixing lines 512a, 512b (e.g., 50 tons per hour through each mixing line 512a, 512b for a mixing system designed to handle 100 tons per hour).

[0124]

[0134] When one of the mixed lines 512 is closed and goes offline, a part of the heavy oil feedstock changes its route through the bypass line 540, and the heavy oil feedstock 502 passing through the mixing system 500 maintains the same or a similar flow rate of approximately 100 to 300 tons per hour. By way of example and not limitation, for a mixing system 500 designed using a total flow rate of 100 tons per hour, the flow rates of the heavy oil feedstock 502 through the bypass line 540 and the remaining online mixed lines 512 may be the same, i.e., approximately 50 tons per hour through each line. In a preferred embodiment, the flow rate of the heavy oil feedstock 502 through the remaining online mixed lines 512 is increased to more than 50 tons per hour, and the flow rate of the heavy oil feedstock 502 through the bypass line 540 is decreased to less than 50 tons per hour.

[0125]

[0135] For example, the flow rate through the remaining online mixed lines 512 can be increased to match the capacity limits of the mixed lines and mixers, at least about 55 tons per hour, at least about 60 tons per hour, at least about 65 tons per hour, or at least about 70 tons per hour, for example, up to a maximum of about 75 tons per hour. To maintain the same or a similar flow rate of the heavy oil feedstock through a 100 - ton - per - hour system, the corresponding flow rate through the bypass line is about 45 tons per hour or less, or about 40 tons per hour or less, or about 35 tons per hour or less, or about 30 tons per hour or less, for example, about 25 tons per hour.

[0126]

[0136] Alternatively, it is possible to make the flow rate of the heavy oil feedstock 502 through the bypass line 540 greater than the flow rate through the remaining on-line mixing lines 512. For example, the flow rate through the bypass line 540 can be at least about 55 tons per hour, at least about 60 tons per hour, at least about 65 tons per hour or at least about 70 tons per hour, for example up to about 75 tons per hour. To maintain the same or a similar flow rate of the heavy oil feedstock through a 100 ton per hour system, the corresponding flow rate through the remaining on-line mixing lines 512 can be reduced to about 45 tons per hour or less, or about 40 tons per hour or less, or about 35 tons per hour or less, or about 30 tons per hour or less, for example about 25 tons per hour.

[0127]

[0137] The mixing system 500 can be scaled up or down according to the size of the supplied hydrotreating reactor(s), and it is understood that it can have a flow rate of less than 100 tons per hour or more than 100 tons per hour. In such cases, a percentage of the normal capacity can be used to describe the flow rate. If 100% represents the normal flow rate of the heavy oil feedstock 502 during normal operation of the mixing system 500 and then through the parallel mixing lines 512a, 512b, the amount of the heavy oil feedstock 502 passing through each mixing line 512 can be about 50% of the total flow. If one of the mixing lines 512 is closed and taken offline, about 50% of the total flow can be diverted to the bypass line 540, while about 50% of the total flow continues to pass through the remaining on-line mixing lines 512.

[0128]

[0138] In a preferred embodiment, it matches the capacity limits of the mixing line and the mixer, and the flow rate through the remaining online mixing line 512 can be increased to at least about 55% of the total flow through the mixing system 500, at least about 60% of the total flow, at least about 65% of the total flow, or at least about 70% of the total flow, for example, up to about 75% of the total flow. To maintain the same or similar flow rate of the heavy oil feedstock through the mixing system 500, the corresponding flow rate through the bypass line can be about 45% or less of the total flow through the mixing system 500, or about 40% or less of the total flow, or about 35% or less of the total flow, or about 30% or less of the total flow, for example, about 25% of the total flow.

[0129]

[0139] Alternatively, the flow rate of the heavy oil feedstock 502 through the bypass line 540 can be greater than the flow rate through the remaining online mixing line 512. For example, the flow rate through the bypass line 540 can be at least about 55% of the total flow through the mixing system 500, at least about 60% of the total flow, at least about 65% of the total flow, or at least about 70% of the total flow, for example, up to about 75% of the total flow. To maintain the same or similar flow rate of the heavy oil feedstock through the mixing system 500, the corresponding flow rate through the remaining online mixing line 512 can be reduced to about 45% or less of the total flow through the mixing system 500, or about 40% or less of the total flow, or about 35% or less of the total flow, or about 30% or less of the total flow, for example, about 25% of the total flow.

[0130]

[0140] From the foregoing, each parallel mixing line 512a, 512b can have a capacity for operating at a flow rate of about 0 to 55 tons per hour, or about 0 to 60 tons per hour, or about 0 to 65 tons per hour, or about 0 to 70 tons per hour, or about 0 to 75 tons per hour. The bypass line 540 can be configured to have a flow capacity of about 0 to 50 tons per hour, about 0 to 55 tons per hour, or about 0 to 60 tons per hour, or about 0 to 65 tons per hour, or about 0 to 70 tons per hour, or about 0 to 75 tons per hour.

[0131]

[0141] The heavy oil feedstock side stream 536 is used as a diluent to make the diluted precursor mixture 508. When the flow rate of the heavy oil feedstock 502 through the mixing system 500 is about 100 tons per hour, the amount of the heavy oil feedstock side stream 536 may be up to about 10 tons per hour, or up to about 5 tons per hour (or between about 0 - 10 tons per hour or about 0 - 5 tons per hour depending on the conditions within the mixing system 500). When the flow rate of the heavy oil feedstock 502 through the mixing system 500 is less than 100 tons per hour or more than 100 tons per hour, the flow rate of the heavy oil feedstock side stream 536 used as a diluent to make the diluted precursor mixture 508 may be up to about 10% of the total flow, or about 5% (or between about 0 - 10% of the total flow or about 5% depending on the conditions within the mixing system 500).

[0132]

[0142] The adjusted feedstock side stream 532 is used as a diluent to make the diluted precursor mixture 508. When the flow rate of the heavy oil feedstock 502 through the mixing system 500 is about 100 tons per hour, the amount of the adjusted feedstock side stream 532 may be up to about 10 tons per hour, or up to about 5 tons per hour (or between about 0 - 10 tons per hour or about 0 - 5 tons per hour depending on the conditions within the mixing system 500). When the flow rate of the heavy oil feedstock 502 through the mixing system 500 is less than 100 tons per hour or more than 100 tons per hour, the flow rate of the adjusted feedstock side stream 532 used as a diluent to make the diluted precursor mixture 508 may be up to about 10% of the total flow, or about 5% (or between about 0 - 10% of the total flow or about 5% depending on the conditions within the mixing system 500).

[0133]

[0143] Figures 6A-6B illustrate an alternative mixing system 600 that is similar to the hybrid system 500 of FIGS. 5A-5B, but includes three parallel mixing lines 612. The heavy oil feedstock 602 and the diluent precursor mixture 608 are supplied to a common supply line 610 and split into first, second, and third parallel mixing lines 612a, 612b, 612c. By way of example and not limitation, the mixing system 600 is configured to have a total flow rate of heavy oil through the system that is greater than 100 tons per hour, such as 150-350 tons per hour, and can accommodate a larger hydrotreating reactor and a larger capacity of the system.

[0134]

[0144] Each of the mixing lines 612a, 612b, 612c may include upstream valves 614a, 614b, 614c that can be selectively opened during operation of the mixing lines 612a, 612b, 612c and closed for maintenance and cleaning to take the mixing lines 612 offline. When online, the upstream valves 614a, 614b, 614c are opened to allow split flows of the heavy oil feedstock 602 and the diluent precursor mixture 608 to flow into the first, second, and third mixing lines 612a, 612b, 612c. In a preferred embodiment, the parallel mixing lines 612 are designed using symmetric piping and mixing devices such that the pressure drop is substantially equal through each of the parallel mixing lines 612, and an equivalent flow can be maintained between different mixing lines 612. Nevertheless, different capacity and flow mixing lines 612 can be used, for example, when retrofitting a single or double row of mixing lines to include one or more additional mixing lines.

[0135]

[0145] In the hybrid system 600 shown in FIG. 6A, the split streams of the heavy oil feedstock 602 and the pre-dilution precursor mixture 608 in the hybrid lines 612a, 612b, 612c each pass through static in-line mixers 616a, 616b, 616c for an initial mixing to produce first, second, and third initial mixing streams, which pass through corresponding strainers 618a, 618b, 618c to remove any unwanted solids in the initial mixing streams. The mixing streams are then each supplied to high-shear mixers 620a, 620b, 620c to provide first, second, and third conditioned feed streams. Optional first, second, and third flow meters 622a, 622b, 622c can be provided to measure the flow through each of the three hybrid lines 612 downstream of the high-shear mixer 620.

[0136]

[0146] FIG. 6B is similar to FIG. 6A, except that a common static in-line mixer 616 is located in the common supply line 610 and functions as a premixer upstream of the point where the first, second, and third parallel hybrid lines 612a, 612b, and 612c branch, and the individual static in-line mixers 616a, 616b, 616c in the hybrid lines 612a, 612b, and 612c are omitted.

[0137]

[0147] Flow control devices 624a, 624b, 624c are each located downstream of each of the high-shear mixers 620a, 620b, 620c. The flow control devices 624 can provide a multifaceted function. When all of the first, second, and third parallel hybrid lines 612a, 612b, 612c are online, the flow control devices 624a, 624b, 624c are open. When one of the hybrid lines 612 is offline, the corresponding flow control device 624 can be closed to prevent the backflow of pressurized conditioned feed from the other hybrid lines 612 that are still in operation. The flow control device 624 for each of the hybrid lines 612 that are still in operation can be open throughout or can be partially closed to restrict the flow and increase the upstream pressure to cause or allow a portion of the heavy oil feedstock to enter the bypass line 640.

[0138]

[0148] The adjusted feed streams from the first, second, and third blending lines 612a, 612b, 612c are supplied to a common discharge line 625 and combined to form a common adjusted feed stream 646. The common adjusted feed stream 646 passes through a common flow measurement device 628 (e.g., a flow meter) and then through a common flow control device 626 (e.g., a valve), where it is remixed with any heavy oil feed from the bypass line 640 and then enters the surge tank 630.

[0139]

[0149] When all of the parallel blending lines 612a, 612b, 612c are operating online, the flow control device 626 is open. When one of the blending lines 612a, 612b, 612c is closed and taken offline, the common flow control device 626 can partially close to restrict the flow of material through the common discharge line 625, increasing the upstream pressure and causing or allowing some of the heavy oil feed to enter the bypass line 640. The common flow control device 626 can be used alone or in combination with one or both of the flow control devices 624 corresponding to the blending lines 612 that are still in operation.

[0140]

[0150] The bypass line 640 typically does not have the heavy oil feedstock 602 flowing through it when the mixing lines 612a, 612b, 612c are operating online. However, when one of the parallel mixing lines 612 is closed and taken offline, a portion of the heavy oil feedstock 602 that is not supplied to the remaining online mixing lines 612 causes or enables the passage through the bypass line 640 in order to maintain the throughput of the heavy oil feedstock 602 through the mixing system 600. As discussed above, the flow of the heavy oil feedstock 602 through the bypass line 640 is caused or induced by restricting the flow through the common discharge line 625 by partially closing the common flow control valve 626 and / or the mixing line valve 624 of the operating mixing lines 612. This induces a pressure drop and increases the upstream pressure sufficient to cause a portion of the heavy oil feedstock 602 to enter the bypass line 640. An optional flow meter 642 in the bypass line 640 measures the flow rate of the heavy oil feedstock 602 passing through the bypass line 640. The bypass line 640 is joined to the common discharge line 625 to combine the heavy oil feedstock 608 from the bypass line with the common regulated feedstock stream 646 downstream of the flow control device 626 and the flow meter 628.

[0141]

[0151] The flow rates of the split heavy oil feedstock streams passing through the remaining operating mixing lines 612, the common discharge line 625, and the bypass line 640 can be measured respectively by their respective mixing line flow meters 622, the common flow meter 628, and optionally the bypass flow meter 642. The respective flow rates of the materials passing through the remaining operating mixing line 612 and the bypass line 640 can be adjusted by adjusting against the common flow control valve 626, the mixing line valve 624, and / or the bypass line valve 644. By using flow meters to measure the flow rates and flow control devices to perform the adjustment, the desired balance of the flows through the various lines can be achieved and maintained. In addition to adjusting the flow rate through the bypass line 640, when the three mixing lines 612 are open and operating, the bypass line valve 644 can be closed or partially restricted to balance the line pressures to ensure that the heavy oil feedstock 602 does not pass through the bypass line 640 in either the forward or reverse direction.

[0142]

[0152] An exemplary method of mixing a catalyst precursor into heavy oil includes using the mixing system 600 illustrated in FIG. 6A, (1) blending an amount of catalyst precursor 604 with an amount of diluent 606 to form a pre-dilution precursor mixture 608, (2) using three parallel mixing lines 612a, 612b, 612c, each parallel mixing line 612 including one or more mixers 616, 620 and at least one valve 614, 624 for adjusting the flow of the mixing line 612, to mix the pre-dilution precursor mixture 608 with the heavy oil feedstock 602 to form three adjusted feedstock streams, (3) combining the adjusted feedstock streams in a common discharge line 625 downstream of the three parallel mixing lines 612 to form a common adjusted feedstock stream 646, (4) Stopping the flow through one of the hybrid lines 612 and causing or enabling a portion of the heavy oil feedstock 602 to enter the bypass line 640, bypass the parallel hybrid lines 612, and combine with the common regulated feedstock stream 646 in the common discharge line 625, and (5) While a portion of the heavy oil feedstock 602 is passing through the bypass line 640, continuing to mix at least a portion of the dilution precursor mixture 608 with the remaining portion of the heavy oil feedstock 602 using the other two of the parallel hybrid lines 612.

[0143]

[0153] When using the alternative mixing system 600 illustrated in FIG. 6B, the method optionally includes premixing the dilution precursor mixture 608 with the heavy oil feedstock 602 using a common static in-line mixer 616 upstream of where the first, second, and third mixing lines 612a, 612b, 612c branch. The method also omits mixing the dilution precursor mixture 608 with the heavy oil feedstock 602 using the static in-line mixers 616a, 616b, 616c of the mixing lines 612a, 612b, 612c illustrated in FIG. 6A.

[0144]

[0154] By way of illustration and not limitation, a large hydrotreating system may require a heavy oil flow rate of 150 to 350 tons per hour. When operating the first, second, and third parallel hybrid lines 612a, 612b, 612c, it may be advantageous or preferable to divide the heavy oil feedstock 602 equally such that there is a symmetric (e.g., equal) flow of material through each of the parallel hybrid lines 612a, 612b, 612c (e.g., 50 tons per hour through each mixing line 612 for a mixing system designed to handle 150 tons per hour).

[0145]

[0155] When one of the three mixing lines 612 is closed and offline, a part of the heavy oil feedstock changes its route through the bypass line 640, and the heavy oil feedstock 602 passing through the mixing system 600 maintains the same or similar flow rate of approximately 150 to 350 tons per hour. By way of example and not limitation, for a mixing system 600 designed using a total flow rate of 150 tons per hour, the flow rate of the heavy oil feedstock 602 through each of the bypass line 640 and the remaining online mixing lines 612 may be the same, i.e., it may pass through each line at approximately 50 tons per hour. In a preferred embodiment, the flow rate of the heavy oil feedstock 602 through each remaining online mixing line 612 is increased to more than 50 tons per hour, and the flow rate of the heavy oil feedstock 602 through the bypass line 640 is decreased to less than 50 tons per hour.

[0146]

[0156] For example, the flow rate through one or both of the remaining online mixing lines 612 can be increased to match the capacity limits of the mixing lines and mixers, at least about 53 tons per hour, at least about 56 tons per hour, at least about 59 tons per hour, or at least about 62 tons per hour, for example up to a maximum of about 65 tons per hour. To maintain the same or similar flow rate of the heavy oil feedstock through a 150 - ton - per - hour system, the corresponding flow rate through the bypass line can be about 44 tons per hour or less, or about 38 tons per hour or less, or about 32 tons per hour or less, or about 26 tons per hour or less, for example, it may be about 20 tons per hour.

[0147]

[0157] Alternatively, it is possible to make the flow rate of the heavy oil feedstock 602 through the bypass line 640 greater than the flow rate through the remaining on-line mixing lines 612. For example, the flow rate through the bypass line 640 can be at least about 55 tons per hour, at least about 60 tons per hour, at least about 65 tons per hour, or at least about 70 tons per hour, for example up to about 75 tons per hour. To maintain the same or a similar flow rate of the heavy oil feedstock through a 150 tons per hour system, the corresponding combined flow rate through one or both of the remaining on-line mixing lines 612 can be reduced to about 95 tons per hour or less, or about 90 tons per hour or less, or about 85 tons per hour or less, or about 80 tons per hour or less, for example about 75 tons per hour.

[0148]

[0158] The mixing system 600 can be scaled up or down according to the size of the supplied hydrotreating reactor(s), and it is understood that it can have a flow rate of less than 150 tons per hour or more than 150 tons per hour. In such cases, a percentage of normal capacity can be used to describe the flow rate. If 100% represents the normal flow rate of the heavy oil feedstock 602 during normal operation of the mixing system 600 and then through the three parallel mixing lines 612a, 612b, 612c, the amount of heavy oil feedstock 602 passing through each mixing line 612 can be about 33% of the total flow. If one of the mixing lines 612 is closed and taken offline, about 33% of the total flow can be diverted to the bypass line 640, while about 67% of the total flow continues to pass through the remaining on-line mixing line 612.

[0149]

[0159] In a preferred embodiment, it matches the capacity limits of the mixing line and the mixer, and the combined flow rate through the remaining on-line mixing line 612 can be increased to at least about 70% of the total flow, at least about 75% of the total flow, at least about 80% of the total flow, or at least about 85% of the total flow, for example, up to about 90% of the total flow. To maintain the same or similar flow rate of the heavy oil feedstock through the system, the corresponding flow rate through the bypass line can be about 30% or less of the total flow, or about 25% or less of the total flow, or about 20% or less of the total flow, or about 15% or less of the total flow, for example, about 10% of the total flow.

[0150]

[0160] Alternatively, the flow rate of the heavy oil feedstock 602 through the bypass line 640 can be greater than the flow rate through each of the remaining on-line mixing lines 612. For example, the flow rate through the bypass line 640 can be at least about 35% of the total flow through the mixing system 600, at least about 40% of the total flow, at least about 45% of the total flow, or at least about 50% of the total flow, for example, up to about 55% of the total flow. To maintain the same or similar flow rate of the heavy oil feedstock through the mixing system 600, the combined flow rate through the remaining on-line mixing lines 612 can be reduced to about 65% or less of the total flow through the mixing system 600, or about 60% or less of the total flow, or about 55% or less of the total flow, or about 50% or less of the total flow, for example, about 45% of the total flow.

[0151]

[0161] From the foregoing points of view, each parallel mixing line 612a, 612b, 612c can have a capacity for operating at a flow rate of about 0 to 53 tons per hour, or about 0 to 56 tons per hour, or about 0 to 59 tons per hour, or about 0 to 62 tons per hour, or about 0 to 65 tons per hour. The bypass line 640 can be configured to have a flow capacity of about 0 to 50 tons per hour, about 0 to 55 tons per hour, or about 0 to 60 tons per hour, or about 0 to 65 tons per hour, or about 0 to 70 tons per hour, or about 0 to 75 tons per hour, or about 0 to 80 tons per hour, or about 0 to 90 tons per hour, or about 0 to 100 tons per hour. Accordingly, FIGS. 6A-6B illustrate a method by which the capacity of the mixing system 600 can be increased by about 50% or more without increasing the capacity of each mixing line 612. However, it is understood that the mixing line 612 can have a smaller or larger capacity as desired.

[0152]

[0162] FIGS. 7A-7B are similar to the mixing system 500 of FIGS. 5A-5B and the mixing system 600 of FIGS. 6A-6B, and illustrate an alternative mixing system 700 that includes four parallel mixing lines 712. The heavy oil feedstock 702 and the pre-dilution precursor mixture 708 are supplied to a common supply line 710 and split into four parallel mixing lines 712a, 712b, 712c, 712d. By way of example and not limitation, the mixing system 700 is configured to have a total flow rate of heavy oil through the system of greater than 150 tons per hour, such as 200 to 400 tons per hour, etc., and can accommodate a larger hydroprocessing reactor and a larger capacity of the system.

[0153]

[0163] Each of the mixing lines 712a, 712b, 712c, 712d may include upstream valves 714a, 714b, 714c, 714d, which can be selectively opened during operation of the mixing lines 712a, 712b, 712c, 714d and closed to take the mixing line 712 offline for maintenance and cleaning. When online, the upstream valves 714a, 714b, 714c, 714d are opened to allow split flows of the heavy oil feedstock 702 and the diluent precursor mixture 708 to flow into the first, second, third, and fourth mixing lines 712a, 712b, 712c, 714d. In a preferred embodiment, the parallel mixing lines 712 are designed using symmetric piping and mixing devices such that the pressure drop is substantially equal through each parallel mixing line 712, and an equivalent flow can be maintained between different mixing lines 712. Nevertheless, different capacity and flow mixing lines 712 can be used, for example, when retrofitting single, double, or triple rows of mixing lines to include one or more additional mixing lines.

[0154]

[0164] In the mixing system 700 shown in FIG. 7A, split flows of the heavy oil feedstock 702 and the diluent precursor mixture 708 in the mixing lines 712a, 712b, 712c, 712d each pass through static in-line mixers 716a, 716b, 716c, 716d for initial mixing to produce first, second, third, and fourth initial mixed flows, which pass through corresponding strainers 718a, 718b, 718c, 718d to remove any undesirable solids in the initial mixed flows. The mixed flows are then each supplied to high-shear mixers 720a, 720b, 720c, 720d to provide first, second, third, and fourth conditioned feedstock flows. Optional first, second, third, and fourth flow meters 722a, 722b, 722c, 722d can be provided to measure the flow through each of the four mixing lines 712 downstream of the high-shear mixer 720.

[0155]

[0165] Figure 7B is the same as Figure 7A, except that the common static in-line mixer 716 is located in the common supply line 710 and functions as a premixer upstream of the point where the first, second, third, and fourth parallel mixing lines 712a, 712b, 712c, 712d branch, and the individual static in-line mixers 716a, 716b, 716c, 716d in the mixing lines 712a, 712b, 712c, 712d are omitted.

[0156]

[0166] The flow control devices 724a, 724b, 724c, 742d are each located downstream of each of the high-shear mixers 720a, 720b, 720c, 720d. The flow control device 724 can provide a multifaceted function. When all of the first, second, third, and fourth parallel mixing lines 712a, 712b, 712c, 714d are online, the flow control devices 724a, 724b, 724c, 724d are open. When one or two of the mixing lines 712 are offline, the corresponding flow control device(s) 724 is closed to prevent the backflow of the pressurized and adjusted feedstock from the other mixing lines 712 that are still in operation. Each flow control device 724 of each mixing line 712 that is still in operation may be open throughout the process, or may be partially closed to restrict the flow, increase the upstream pressure, and cause or allow a portion of the heavy oil feedstock to enter the bypass line 740.

[0157]

[0167] The adjusted feedstock flows from the first, second, third, and fourth mixing lines 712a, 712b, 712c, 712d are supplied to a common discharge line 725, combined to form a common adjusted feedstock flow 746. The common adjusted feedstock flow 746 passes through a common flow measurement device 728 (e.g., a flow meter), then through a common flow control device 726 (e.g., a valve), is remixed with any heavy oil feedstock from the bypass line 740, and then enters the surge tank 730.

[0158]

[0168] When all of the parallel mixing lines 712a, 712b, 712c, and 712d are operating online, the flow control device 726 is open. When one or two of the mixing lines 712a, 712b, 712c, 712d are closed and taken offline, the common flow control device 726 partially closes to restrict the flow of material through the common discharge line 725, creating a pressure drop that can cause or allow a portion of the heavy oil feedstock to enter the bypass line 740. The common flow control device 726 can be used alone or in combination with one or more flow control devices 724 corresponding to the mixing lines 712 that are still in operation.

[0159]

[0169] The bypass line 740 typically does not have the heavy oil feedstock 702 flowing through it when the mixing lines 712a, 712b, 712c, 712d are operating online. However, when one or two of the parallel mixing lines 712 are closed and taken offline, a portion of the heavy oil feedstock 702 that is not supplied to the remaining online mixing lines 712 causes or allows passage through the bypass line 740 to maintain the throughput of the heavy oil feedstock 702 through the mixing system 700. As discussed above, the flow of the heavy oil feedstock 702 through the bypass line 740 is caused or induced by restricting the flow through the common discharge line 725 by partially closing the common flow control valve 726 and / or the mixing line valves 724 of the operating mixing lines 712. This induces a pressure drop and increases the upstream pressure sufficient to cause a portion of the heavy oil feedstock 702 to enter the bypass line 740. An optional flow meter 742 in the bypass line 740 measures the flow rate of the heavy oil feedstock 702 passing through the bypass line 740. The bypass line 740 is joined to the common discharge line 725 to combine the heavy oil feedstock 708 from the bypass line with the common regulated feedstock stream 746 downstream of the flow control device 726 and the flow meter 728.

[0160]

[0170] The flow rates of the split heavy oil feedstock streams passing through the remaining operating mixing lines 712, the common discharge line 725, and the bypass line 740 can be measured respectively by their respective mixing line flow meters 722, the common flow meter 728, and optionally the bypass flow meter 742. The respective flow rates of the materials passing through the remaining operating mixing lines 712 and the bypass line 740 can be adjusted by adjusting them with respect to the common flow control valve 726, the mixing line valves 724, and / or the bypass line valve 744. By using flow meters to measure the flow rates and flow control devices to perform the adjustment, the desired balance of the flows through the various lines can be achieved and maintained. In addition to adjusting the flow rate through the bypass line 740, when the four mixing lines 712 are open and operating, to ensure that the heavy oil feedstock 702 does not pass through the bypass line 740 in either the forward or backward direction, the bypass line valve 744 can be closed or partially restricted to balance the line pressures.

[0161]

[0171] An exemplary method of mixing a catalyst precursor into heavy oil includes using the mixing system 700 illustrated in FIG. 7A, (1) blending an amount of catalyst precursor 704 with an amount of diluent 706 to form a pre-dilution precursor mixture 708, (2) using four parallel mixing lines 712a, 712b, 712c, 714d, each parallel mixing line 712 including one or more mixers 716, 720 and at least one valve 714, 724 for adjusting the flow of the mixing line 712, to mix the pre-dilution precursor mixture 708 with the heavy oil feedstock 702 to form four adjusted feedstock streams, (3) combining the adjusted feedstock streams in a common discharge line 725 downstream of the four parallel mixing lines 712 to form a common adjusted feedstock stream 746, (4) Stopping the flow through one or two of the hybrid lines 712, and causing or enabling a portion of the heavy oil feedstock 702 to enter the bypass line 740, bypass the parallel hybrid lines 712, and combine with the common regulated feedstock stream 746 in the common discharge line 725, and (5) While a portion of the heavy oil feedstock 702 is passing through the bypass line 740, continuing to mix at least a portion of the dilution precursor mixture 708 with the remaining portion of the heavy oil feedstock 702 using the other two or three of the parallel hybrid lines 712.

[0162]

[0172] When using the alternative mixing system 700 illustrated in FIG. 7B, the method optionally includes premixing the dilution precursor mixture 708 with the heavy oil feedstock 702 using a common static in-line mixer 716 upstream of the point where the first, second, third, and fourth mixing lines 712a, 712b, 712c, 712d branch. This method also omits mixing the dilution precursor mixture 708 with the heavy oil feedstock 702 using the static in-line mixers 716a, 716b, 716c, 712d of the mixing lines 712a, 712b, 716c, 716d illustrated in FIG. 7A.

[0163]

[0173] By way of illustration and not limitation, a very large hydrotreating system may require a heavy oil flow rate of 200 to 400 tons per hour. When operating the first, second, third, and fourth parallel hybrid lines 712a, 712b, 712c, 712d, it may be advantageous or preferable to equally divide the heavy oil feedstock 702 such that there is a symmetric (e.g., equal) flow of material through each of the parallel hybrid lines 712a, 712b, 712c, 712d (e.g., 50 tons per hour through each hybrid line 712 for a mixing system designed to handle 200 tons per hour).

[0164]

[0174] When one or two of the four mixing lines 712 are closed and offline, a portion of the heavy oil feedstock changes routes through the bypass line 740, and the heavy oil feedstock 702 passing through the mixing system 700 maintains a flow rate of approximately 200 to 400 tons per hour that is the same or similar. By way of example and not limitation, for a mixing system 700 designed to have a total flow rate of 200 tons per hour, the flow rate of the heavy oil feedstock 702 through each of the bypass line 740 and the remaining online mixing lines 712 may be the same, for example, it may pass through each line at approximately 50 tons per hour. In a preferred embodiment, the flow rate of the heavy oil feedstock 702 through each remaining online mixing line 712 is increased to more than 50 tons per hour, and the flow rate of the heavy oil feedstock 702 through the bypass line 740 is decreased to less than 50 tons per hour.

[0165]

[0175] For example, the flow rate through at least one remaining online mixing line 712 may be increased to match the capacity limits of the mixing line and mixer and be at least about 52 tons per hour, at least about 54 tons per hour, at least about 56 tons per hour, or at least about 58 tons per hour, for example, up to a maximum of about 60 tons per hour. When one of the mixing lines 712 is closed, to maintain the same or similar flow rate of the heavy oil feedstock through a 200-ton-per-hour system, the corresponding flow rate through the bypass line may be about 44 tons per hour or less, or about 38 tons per hour or less, or about 32 tons per hour or less, or about 26 tons per hour or less, for example, it may be about 20 tons per hour. When two of the mixing lines 712 are closed, to maintain the same or similar flow rate of the heavy oil feedstock through a 200-ton-per-hour system, the corresponding flow rate through the bypass line may be about 96 tons per hour or less, or about 92 tons per hour or less, or about 88 tons per hour or less, or about 84 tons per hour or less, for example, it may be about 80 tons per hour.

[0166]

[0176] Alternatively, it is possible to make the flow rate of the heavy oil feedstock 702 through the bypass line 740 greater than the flow rate through the remaining on-line mixing lines 712. For example, the flow rate through the bypass line 740 can be at least about 55 tons per hour, at least about 60 tons per hour, at least about 65 tons per hour or at least about 70 tons per hour, for example up to about 75 tons per hour. To maintain the same or a similar flow rate of the heavy oil feedstock through a 200 tons per hour system, the corresponding combined flow rate through the remaining on-line mixing lines 712 can be reduced to about 145 tons per hour or less, or about 140 tons per hour or less, or about 135 tons per hour or less, or about 130 tons per hour or less, for example about 125 tons per hour.

[0167]

[0177] The mixing system 700 can be scaled up or down according to the size of the supplied hydrotreating reactor(s), and it is understood that it can have a flow rate of less than 200 tons per hour or more than 200 tons per hour. In such cases, the percentage of normal capacity can be used to describe the flow rate. If 100% represents the normal flow rate of the heavy oil feedstock 702 during normal operation of the mixing system 700 and then through the four parallel mixing lines 712a, 712b, 712c, 712d, the amount of the heavy oil feedstock 702 passing through each mixing line 712 may be about 25% of the total flow. If one of the mixing lines 712 is closed and taken offline, about 25% of the total flow can be diverted to the bypass line 740, while about 75% of the total flow continues to pass through the remaining on-line mixing lines 712. If two of the mixing lines 712 are closed and taken offline, about 25 - 50% of the total flow can be diverted to the bypass line 740, while about 50 - 75% of the total flow continues to pass through the remaining on-line mixing lines 712.

[0168]

[0178] In a preferred embodiment, the combined flow rate through the remaining on-line mixing line 712, which matches the capacity limits of the mixing line and the mixer, can be increased to at least about 75% of the total flow, at least about 80% of the total flow, at least about 85% of the total flow, or at least about 90% of the total flow, for example up to about 95% of the total flow. To maintain the same or a similar flow rate of the heavy oil feedstock through the system, the corresponding flow rate through the bypass line can be about 25% or less of the total flow, or about 20% or less of the total flow, or about 15% or less of the total flow, or about 10% or less of the total flow, for example about 5% of the total flow.

[0169]

[0179] Alternatively, the flow rate of the heavy oil feedstock 702 through the bypass line 740 can be greater than the flow rate through each of the remaining on-line mixing lines 712. For example, the flow rate through the bypass line 740 can be at least about 27.5% of the total flow through the mixing system 700, at least about 30% of the total flow, at least about 32.5% of the total flow, or at least about 35% of the total flow, for example up to about 37.5% of the total flow. To maintain the same or a similar flow rate of the heavy oil feedstock through the mixing system 700, the combined flow rate through the remaining on-line mixing lines 712 can be reduced to about 72.5% or less of the total flow through the mixing system 700, or about 70% or less of the total flow, or about 67.5% or less of the total flow, or about 65% or less of the total flow, for example about 62.5% of the total flow.

[0170]

[0180] From the foregoing, each of the parallel mixing lines 712a, 712b, 712c, 712d can have a capacity for operating at a flow rate of about 0 to 52 tons per hour, or about 0 to 54 tons per hour, or about 0 to 56 tons per hour, or about 0 to 58 tons per hour, or about 0 to 60 tons per hour. The bypass line 740 can be configured to have a flow capacity of about 0 to 50 tons per hour, about 0 to 55 tons per hour, or about 0 to 60 tons per hour, or about 0 to 65 tons per hour, or about 0 to 70 tons per hour, or about 0 to 75 tons per hour, or about 0 to 80 tons per hour, or about 0 to 90 tons per hour, or about 0 to 100 tons per hour. Thus, FIGS. 7A and 7B illustrate a way in which the capacity of the mixing system 700 can be increased by about 100% without increasing the capacity of each mixing line 712. However, it is understood that the mixing lines 712 can have smaller or larger capacities as desired.

[0171]

[0181] In some embodiments, the dispersed metal sulfide catalyst particles are formed in-situ within the entire heavy oil added to the hydrotreating reactor. This can be achieved by first using the mixing methods and systems of the present disclosure to mix a catalyst precursor with a diluent to form a diluted precursor mixture, which is then mixed with the entire heavy oil in a plurality of parallel mixing lines to form parallel adjusted feed streams, and the parallel adjusted feed streams are combined with a periodic heavy oil feedstock from a bypass line into a common adjusted feed stream, which is then heated to decompose the catalyst precursor and cause or enable a reaction of the catalyst metal with sulfur and / or sulfur-containing molecules in and / or added to the heavy oil to form the dispersed metal sulfide catalyst particles in-situ.

[0172]

[0182] The catalyst precursor may be oil soluble and may have a decomposition temperature in the range of about 100°C (212°F) to about 350°C (662°F), or in the range of about 150°C (302°F) to about 300°C (572°F), or in the range of about 175°C (347°F) to about 250°C (482°F). Examples of catalyst precursors include organometallic complexes or compounds, more specifically oil soluble compounds or complexes of transition metals and organic acids, that have a decomposition temperature or range high enough to avoid substantial decomposition when mixed with a heavy oil feedstock under suitable mixing conditions. When the catalyst precursor is mixed with a hydrocarbon oil diluent, it is advantageous to maintain the diluent below a temperature at which significant decomposition of the catalyst precursor occurs. One skilled in the art will select a mixing temperature profile that will result in intimate mixing of the selected precursor composition without substantial decomposition prior to the in situ formation of the dispersed metal sulfide catalyst particles.

[0173]

[0183] Examples of catalyst precursors include, but are not limited to, molybdenum 2-ethylhexanoate, molybdenum octoate, molybdenum naphthenate, vanadium naphthenate, vanadium octoate, molybdenum hexacarbonyl, vanadium hexacarbonyl, and iron pentacarbonyl. Other catalyst precursors include molybdenum salts that include a plurality of cationic molybdenum atoms and a plurality of carboxylate anions of at least 8 carbon atoms, and that are at least one of (a) aromatic, (b) alicyclic, or (c) branched, unsaturated, and aliphatic. By way of example, each carboxylate anion can have 8 to 17 carbon atoms, or 11 to 15 carbon atoms. Examples of carboxylate anions that fit into at least one of the foregoing categories include carboxylate anions derived from a carboxylic acid selected from the group consisting of 3-cyclopentylpropionic acid, cyclohexanebutyric acid, biphenyl-2-carboxylic acid, 4-heptylbenzoic acid, 5-phenylvaleric acid, geranic acid (3,7 dimethyl-2,6-octadienoic acid), and combinations thereof.

[0174]

[0184] In other embodiments, the carboxylic acid anions suitable for use in the preparation of oil-soluble and thermally stable molybdenum catalyst precursor compounds are derived from carboxylic acids selected from the group consisting of 3-cyclopentylpropionic acid, cyclohexanebutanoic acid, biphenyl-2-carboxylic acid, 4-heptylbenzoic acid, 5-phenylvaleric acid, geranic acid (3,7-dimethyl-2,6-octadienoic acid), 10-undecenoic acid, dodecanoic acid, and combinations thereof. It has been discovered that molybdenum catalyst precursors prepared using carboxylic acid anions derived from the aforementioned carboxylic acids have improved thermal stability.

[0175]

[0185] Catalyst precursors with high thermal stability can have a first decomposition temperature above 210 °C, above about 225 °C, above about 230 °C, above about 240 °C, above about 275 °C, or above about 290 °C. Such catalyst precursors can have a peak decomposition temperature above 250 °C, or above about 260 °C, or above about 270 °C, or above about 280 °C, or above about 290 °C, or above about 330 °C.

[0176]

[0186] In some embodiments, the conditioned feedstock is preheated using heating equipment before entering the hydrotreating reactor to form in situ at least a portion of the dispersed metal sulfide catalyst particles in the heavy oil before entering the reactor. In other embodiments, the conditioned feedstock can be heated or further heated in the hydrotreating reactor to form in situ at least a portion of the dispersed metal sulfide catalyst particles in the heavy oil.

[0177]

[0187] Using the mixing method and system of the present disclosure, dispersed metal sulfide catalyst particles can be formed in a multi-step process. First, an oil-soluble catalyst precursor is premixed with a hydrocarbon diluent to form a diluted precursor mixture. Examples of suitable hydrocarbon diluents include, but are not limited to, vacuum gas oil (typically having a nominal boiling point range of 360 - 524 °C) (680 - 975 °F), decanted oil or cycle oil (typically having a nominal boiling point range of 360 °C - 550 °C) (680 - 1022 °F), and atmospheric gas oil (typically having a nominal boiling point range of 200 °C - 360 °C) (392 - 680 °F), a portion of the heavy oil feedstock, and other hydrocarbons boiling at temperatures above about 200 °C.

[0178]

[0188] The ratio of the catalyst precursor to the hydrocarbon oil diluent used to make the diluted precursor mixture can range from about 1:500 to about 1:1, or from about 1:150 to about 1:2, or from about 1:100 to about 1:5 (e.g., 1:100, 1:50, 1:30, or 1:10). The amount of catalyst metal (e.g., molybdenum) in the diluted precursor mixture is preferably in the range of about 100 weight ppm to about 7000 weight ppm of the diluted precursor mixture, more preferably in the range of about 300 weight ppm to about 4000 weight ppm of the diluted precursor mixture.

[0179]

[0189] The catalyst precursor is preferably mixed with the hydrocarbon diluent at a temperature below the temperature at which a substantial portion of the catalyst precursor decomposes. Mixing may be carried out at a temperature in the range of about 25 °C (77 °F) to about 250 °C (482 °F), or in the range of about 50 °C (122 °F) to about 200 °C (392 °F), or in the range of about 75 °C (167 °F) to about 150 °C (302 °F) to form the diluted precursor mixture. The temperature at which the diluted precursor mixture is formed can depend on the decomposition temperature and / or other characteristics of the catalyst precursor utilized, and / or the characteristics of the hydrocarbon diluent such as viscosity.

[0180]

[0190] The catalyst precursor is preferably mixed with the diluent for a period in the range of about 0.1 second to about 5 minutes, or about 0.3 second to about 3 minutes, or about 0.5 second to about 1 minute, or about 0.7 second to about 30 seconds, or about 1 second to about 10 seconds. The actual mixing time depends at least in part on the temperature (i.e., which affects the viscosity of the fluid) and the mixing intensity. The mixing intensity depends at least in part on, for example, the number of stages for an in-line static mixer.

[0181]

[0191] Pre-blending the catalyst precursor with a hydrocarbon diluent to form a diluted precursor mixture, and subsequently blending the diluted precursor mixture with the heavy oil feedstock significantly aids in thoroughly and intimately blending the catalyst precursor within the feedstock in a relatively short time required especially for large-scale industrial operations. Forming the diluted precursor mixture reduces or eliminates the solubility difference between the more polar catalyst precursor and the more hydrophobic heavy oil feedstock, reduces or eliminates the rheology difference between the catalyst precursor and the heavy oil feedstock, and / or decomposes the catalyst precursor molecules to form solutes in the hydrocarbon diluent that are more readily dispersed within the heavy oil feedstock, thereby shortening the overall mixing time.

[0182]

[0192] The diluted precursor mixture is combined with the heavy oil to disperse the catalyst precursor throughout the heavy oil and form a conditioned feedstock in which the catalyst precursor is thoroughly mixed with the feedstock prior to pyrolysis and in-situ formation of the active metal sulfide catalyst particles. The diluted precursor mixture and the heavy oil feedstock are advantageously mixed for a period in the range of about 0.1 second to about 5 minutes, or about 0.5 second to about 3 minutes, or about 1 second to about 1 minute to obtain sufficient mixing of the catalyst precursor within the heavy oil feedstock. Increasing the intensity and / or shear energy of the mixing process generally reduces the time required to achieve complete mixing.

[0183]

[0193] Examples of mixing equipment that can be used to effect complete mixing of the undiluted precursor mixture and the heavy oil include, but are not limited to, high shear mixing such as mixing created within a vessel having a propeller or turbine impeller, static in-line mixers, static in-line mixers combined with in-line high shear mixers, static in-line mixers combined with in-line high shear mixers followed by a surge tank, the foregoing combinations followed by one or more multi-stage centrifugal pumps, and one or more multi-stage centrifugal pumps. According to some embodiments, continuous mixing rather than batch mixing can be carried out using a high energy pump having a plurality of chambers, in which the catalyst precursor and the heavy oil feedstock are agitated and mixed as part of the pumping process itself. The foregoing mixing equipment may also be used in the pre-mixing process contemplated in forming a catalyst precursor mixture by mixing the catalyst precursor with a hydrocarbon diluent.

[0184]

[0194] In the case of a heavy oil feedstock that is solid at room temperature or extremely viscous, such a feedstock can advantageously be heated to soften it and produce a feedstock having a sufficiently low viscosity so that the oil-soluble catalyst precursor can be well mixed into the feedstock. Generally, reducing the viscosity of the heavy oil feedstock reduces the time required to effect complete and intimate mixing of the oil-soluble precursor composition within the feedstock. However, it can also cause premature decomposition of the catalyst precursor. A catalyst precursor having a decomposition temperature suitable for a given heavy oil feedstock can be selected.

[0185]

[0195] The heavy oil feedstock and the catalyst precursor and / or undiluted precursor mixture are advantageously mixed at a temperature in the range of about 25°C (77°F) to about 350°C (662°F), or in the range of about 50°C (122°F) to about 300°C (572°F), or in the range of about 75°C (167°F) to about 250°C (482°F) to obtain an adjusted feedstock.

[0186]

[0196] The catalyst precursor is premixed with a hydrocarbon diluent to form a diluted precursor mixture, which is then mixed with the heavy oil feedstock, so the feedstock may be at a temperature above the decomposition temperature of the catalyst precursor. In some cases, the hydrocarbon diluent shields individual catalyst precursor molecules during mixing, preventing them from aggregating to form larger particles, thermally insulating the catalyst precursor molecules from the heat from the heavy oil temporarily, and promoting the dispersion of the catalyst precursor molecules throughout the feedstock quickly enough before they are decomposed to release the metal. Additionally, further heating of the feedstock may be required to release hydrogen sulfide from sulfur-bearing molecules in the heavy oil to form metal sulfide catalyst particles. In this way, the progressive dilution of the catalyst precursor enables a high level of dispersion within the heavy oil, resulting in the formation of highly dispersed metal sulfide catalyst particles even when the feedstock is at a temperature exceeding the decomposition temperature of the catalyst precursor.

[0187]

[0197] After the catalyst precursor is well mixed throughout the heavy oil to obtain a conditioned feedstock, the composition is heated to cause decomposition of the catalyst precursor, thereby releasing the catalyst metal and causing or enabling the reaction of the catalyst metal with sulfur in the heavy oil and / or sulfur added to the heavy oil, and forming active metal sulfide catalyst particles in situ. The metal from the catalyst precursor can first form a metal oxide and then react with sulfur in the heavy oil to obtain a metal sulfide compound that forms the final active catalyst. If the heavy oil contains sufficient or excessive sulfur, the final activated catalyst may be formed in situ by heating the feedstock to a temperature sufficient to release sulfur from the feedstock. In some cases, sulfur may be released at the same temperature at which the precursor composition is decomposed. In other cases, further heating to a higher temperature may be required. Hydrogen sulfide gas can be added to heavy oils that lack sufficient sulfur to form active metal sulfide catalyst particles.

[0188]

[0198] When the catalyst precursor is completely mixed throughout the heavy oil, at least a substantial portion of the free metal ions are sufficiently protected or shielded from other metal ions, and as a result, a molecularly dispersed catalyst can be formed when reacting with sulfur to form a metal sulfide compound. Under some circumstances, slight aggregation occurs, and colloidal-sized catalyst particles may be obtained. However, by taking care to completely mix the catalyst precursor throughout the feedstock prior to thermal decomposition of the catalyst precursor, it is believed that individual catalyst molecules rather than colloidal particles can be obtained. If simply blended without being well mixed, the catalyst precursor containing the feedstock typically causes the formation of large aggregated metal sulfide compounds larger than micrometer size.

[0189]

[0199] To form the dispersed metal sulfide catalyst particles, the conditioned feedstock is heated to a temperature in the range of about 275 °C (527 °F) to about 450 °C (842 °F), or in the range of about 310 °C (590 °F) to about 430 °C (806 °F), or in the range of about 330 °C (626 °F) to about 410 °C (770 °F).

[0190]

[0200] The concentration of the catalytic metal provided by the dispersed metal sulfide catalyst particles in the heavy oil may be in the range of about 1 weight ppm to about 150 weight ppm, or in the range of about 5 weight ppm to about 95 weight ppm, or in the range of about 10 weight ppm to about 90 weight ppm of the heavy oil and any diluent.

[0191]

[0201] When the heavy oil contains a significant amount of asphaltene molecules, the dispersed metal sulfide catalyst particles may preferentially associate with or remain in close proximity to the asphaltene molecules. Since asphaltene molecules are generally more hydrophilic and less hydrophobic than other hydrocarbons contained in the heavy oil, asphaltene molecules can have a higher affinity for the metal sulfide catalyst particles. Since the metal sulfide catalyst particles tend to be hydrophilic, individual particles or molecules tend to move towards the more hydrophilic portions or molecules within the heavy oil.

[0192]

[0202] The highly polar nature of metal sulfide catalyst particles causes or enables association with asphaltene molecules. Generally, however, there is incompatibility between highly polar catalyst compounds and hydrophobic heavy oils, and intimate or complete mixing of the catalyst precursors in the feedstock is required before decomposition and in-situ formation of the active catalyst particles. Since metal catalyst compounds are highly polar, they cannot be effectively dispersed in heavy oil when added directly. In practice, by forming smaller active catalyst particles, a number of catalyst particles are produced that provide catalytic sites more uniformly distributed throughout the heavy oil. It also increases the catalyst surface area.

[0193]

[0203] Complete mixing of the catalyst precursors with the heavy oil feedstock prior to thermal decomposition of the catalyst precursors and formation of the dispersed metal sulfide catalyst particles substantially reduces the rate of fouling of the apparatus, and the fouling rate of the apparatus can be measured by at least one of (i) the frequency of heat exchanger cleaning required, (ii) the frequency of switching to a preheat exchanger, (iii) the frequency of filter replacement, (iv) the frequency of strainer cleaning or replacement, (v) the rate of decrease in the surface temperature of the apparatus, including within an apparatus selected from a heat exchanger, a separator, or a distillation column, (vi) the rate of increase in the metal temperature of the furnace tubes, (vii) the rate of increase in the calculated fouling resistance factors of the heat exchanger and the furnace, (viii) the rate of increase in the differential pressure of the heat exchanger, (ix) the frequency of cleaning of the atmospheric distillation column and / or the vacuum distillation column, or (x) the frequency of regular maintenance.

Example

[0194] V. Example Comparative Example 1

[0204] This example involves a conventional mixing system that includes a single mixing line but no parallel mixing lines (if any) and bypass lines. The mixing line includes one or more high-shear mixers, one or more strainers or filters, one or more static in-line mixers, and optionally other processing devices known in the art. At some point during the operation of the single mixing line, the mixing line requires a maintenance period. For example, the maintenance may include at least one of cleaning one or more strainers or filters, cleaning and / or repairing the high-shear mixer(s), and cleaning and / or repairing the static in-line mixer(s).

[0195]

[0205] Regardless of which part or section of the mixing line is shut down, the mixing line remains online longer and the mixing of the catalyst precursor into the heavy oil feedstock is stopped. One or more consequences or results of shutting down the mixing line for maintenance, for example, may be to completely stop the flow of the diluent precursor mixture into the heavy oil feedstock. By doing so, the hydrocarbon material is supplied to the hydroprocessing reactor downstream of the mixing line at a reduced rate, reducing throughput and / or liquid hourly space velocity.

[0196]

[0206] An alternative outcome or result is to continue to supply the diluent precursor mixture to the heavy oil feedstock at the same rate. By doing so, the rate at which the hydrocarbon material is supplied to the hydrotreating reactor is maintained the same, maintaining throughput and / or liquid hourly space velocity. However, this is only possible if the mixing system is equipped with a bypass line, a feature that is not currently included in conventional mixing systems used to introduce the catalyst precursor into the heavy oil. However, even if such a bypass line is added to an existing single-line mixing system, there is little or no significant mixing of the diluent precursor mixture into the heavy oil, resulting in a concentrated region of the diluent precursor mixture containing the catalyst precursor in a more concentrated form in the hydrocarbon material supplied to the preheater and / or hydrotreating reactor compared to when the mixing line is on-line. If the more concentrated form of the diluent precursor mixture is then exposed to high temperatures, causing decomposition of the catalyst precursor, this results in the formation of substantially larger homogeneous catalyst particles, e.g., having a size of 1 - 300 μm, compared to the in-situ formed dispersed metal sulfide catalyst particles having a size of less than 1 μm that would form in-situ if there was complete mixing of the diluent precursor mixture into the heavy oil feedstock prior to thermal decomposition of the catalyst precursor.

[0197]

[0207] Another alternative outcome or result is to continue to supply the hydrocarbon diluent to the heavy oil feedstock at the same rate without the catalyst precursor. Again, this requires adding a bypass line to a conventional mixing system that does not have a bypass line. Doing this essentially maintains the rate at which the hydrocarbon material is supplied to the hydrotreating reactor and essentially maintains throughput and / or liquid hourly space velocity. However, without the catalyst precursor, there is no in-situ formation of dispersed metal sulfide catalyst particles or other homogeneous catalysts in the heavy oil feedstock. In such a case, the hydrotreating system no longer has such in-situ formed catalysts in the system and must then rely on a fluidized bed catalyst, a fixed bed catalyst, or other catalysts already being used in the hydrotreating reactor.

[0198]

[0208] Still another alternative are several hybrids that reduce but do not completely stop the flow of the diluted precursor mixture into the heavy oil and / or the flow of the catalyst precursor into the hydrocarbon diluent. Any of such alternatives rely on the addition of a bypass line to a conventional mixing system without a bypass line. Also, they essentially preclude the in-situ formation of dispersed metal sulfide catalyst particles having a particle size of less than 1 μm in the heavy oil feedstock.

[0199] Comparative Example 2

[0209] This example involves a mixing system that includes, independently of each other, two full-scale mixing lines that operate to mix the entire catalyst precursor mixture into the heavy oil feedstock. Each full-scale mixing line includes one or more high-shear mixers, one or more strainers or filters, one or more static in-line mixers, and optionally other processing devices known in the art. When one full-scale mixing line is online and functioning, the other is offline, and vice versa. In this way, whenever one mixing line requires maintenance, the other mixing line performs the entire mixing process with the same mixing efficiency.

[0200]

[0210] Even if providing two full-scale mixing lines can solve many or most of the problems of Comparative Example 1, such a mixing system is costly and wasteful. The mixing capacity is doubled, but the cost is approximately doubled, and even when no maintenance is being performed, half of the mixing system is offline and remains idle at all times.

[0201] Example 3

[0211] This example involves the mixing system of the present invention including two parallel mixing lines and a bypass line. Each mixing line includes one or more high-shear mixers, one or more strainers or filters, optionally one or more static in-line mixers, and optionally other processing devices known in the art. The mixing system may optionally include a common static in-line mixer upstream of the point where the two parallel mixing lines branch. During operation of the mixing system, at various times, one of the two parallel mixing lines requires maintenance. For example, the maintenance period may include at least one of cleaning one or more strainers or filters, cleaning and / or repairing the high-shear mixer(s), and cleaning and / or repairing the static in-line mixer(s).

[0202]

[0212] Regardless of which part or section of the mixing line is shut down, the remaining mixing line goes offline and the mixing of the heavy oil feedstock of the catalyst precursor through that line ceases. However, the other parallel mixing line remains online and continues to mix the dilution precursor mixture with at least 50% of the heavy oil feedstock to form the adjusted feedstock, and less than 50% of the remaining feedstock is diverted through the bypass line and recombines with the adjusted feedstock downstream of the remaining mixing line. When one parallel mixing line is offline, the mixing efficiency may decrease, but since the mixing system of Example 3 can still prepare an adjusted feedstock that forms dispersed metal sulfide catalyst particles in situ within the heavy oil feedstock, the overall mixing process is substantially improved compared to Comparative Example 1. Furthermore, the throughput and / or liquid hourly space velocity can be more easily maintained than in Comparative Example 1.

[0203]

[0213] Even if converting a part of the heavy oil feedstock passing through the bypass line during the maintenance period reduces the mixing efficiency of the entire mixing system, the reduction in the overall mixing efficiency can be partially alleviated by increasing the flow rate through the remaining mixing lines, subject to their capacity limits. This increases the mixing efficiency of the remaining mixing lines as compared to the case where the flow rate through the mixing lines is maintained at approximately 50% of the total flow rate through the mixing system.

[0204]

[0214] For example, when operating parallel mixing lines, each mixing line can be operated to mix the dilution catalyst precursor mixture into approximately 50% of the total volume of the heavy oil feedstock flowing through the mixing system. However, if one of the mixing lines is shut down for maintenance, the remaining parallel mixing lines can be temporarily operated at a higher flow rate, subject to their capacity limits, to mix the dilution precursor mixture with a larger amount of the heavy oil feedstock, e.g., approximately 55%, 60%, 65%, 70%, or 75% of the total volume of the heavy oil feedstock flowing through the mixing system, and the remaining (respectively approximately 45%, 40%, 35%, 30%, or 25%) of the heavy oil feedstock flows through the bypass line to maintain the same overall throughput of heavy oil through the mixing system and / or the same liquid hourly space velocity of the heavy oil through the hydrotreating reactor.

[0205] Example 4

[0215] This example involves the mixing system of the present invention including three parallel mixing lines and a bypass line. Each mixing line includes one or more high-shear mixers, one or more strainers or filters, optionally one or more static in-line mixers, and optionally other processing devices known in the art. The mixing system may optionally include a common static in-line mixer upstream of the point where the three parallel mixing lines branch. During operation of the mixing system, at various times, one of the three parallel mixing lines requires maintenance. For example, the maintenance period can include at least one of cleaning one or more strainers or filters, cleaning and / or repairing the high-shear mixer(s), and cleaning and / or repairing the static in-line mixer(s).

[0206]

[0216] Regardless of which part or section of the mixing line is shut down, the maintained mixing line goes offline, and the mixing of the heavy oil feedstock of the catalyst precursor through that line stops. However, other parallel mixing lines remain online and continue to mix the dilution precursor mixture with at least 67% of the heavy oil feedstock to form the adjusted feedstock, and 33% or less of the remaining feedstock is diverted through the bypass line and recombines with the adjusted feedstock downstream of the remaining mixing lines. When one parallel mixing line is offline, the mixing efficiency may decrease, but since the mixing system of Example 4 can still prepare the adjusted feedstock that forms the dispersed metal sulfide catalyst particles in situ in the heavy oil feedstock, the overall mixing process is substantially improved compared to Comparative Example 1. Furthermore, the throughput and / or the liquid hourly space velocity can be easily maintained.

[0207]

[0217] Even if converting a part of the heavy oil feedstock through the bypass line during the maintenance period reduces the mixing efficiency of the entire mixing system, the reduction in the overall mixing efficiency can be partially alleviated by increasing the flow rate through the remaining mixing lines, subject to their capacity limits. This increases the mixing efficiency of the remaining mixing lines compared to the case where the flow rate through the mixing lines is maintained at approximately 33% of the total flow rate through the mixing system.

[0208]

[0218] For example, when operating parallel mixing lines, each mixing line can be operated to mix a dilution catalyst precursor mixture to approximately 33% of the total volume of the heavy oil feedstock flowing through the mixing system. However, if one of the parallel mixing lines is shut down for maintenance, the remaining mixing lines can be temporarily operated at a higher flow rate, subject to their capacity limits, to mix the dilution precursor mixture with a larger volume of the heavy oil feedstock, e.g., in a combined volume that is approximately 70%, 75%, 80%, 85%, or 90% of the total volume of the heavy oil feedstock flowing through the mixing system, and the remainder of the heavy oil feedstock (approximately 30%, 25%, 20%, 15%, or 10% respectively of the total) flows through a bypass line to maintain the same overall throughput of heavy oil through the mixing system and / or the same liquid hourly space velocity of heavy oil through the hydrotreating reactor.

[0209] Example 5

[0219] This example involves the mixing system of the present invention including four parallel mixing lines and a bypass line. Each mixing line includes one or more high shear mixers, one or more strainers or filters, optionally one or more static in-line mixers, and optionally other processing devices known in the art. The mixing system may optionally include a common static in-line mixer upstream of the point where the four parallel mixing lines branch. During operation of the mixing system at various times, one of the four parallel mixing lines requires maintenance. For example, the maintenance period can include at least one of cleaning one or more strainers or filters, cleaning and / or repairing the high shear mixer(s), and cleaning and / or repairing the static in-line mixer(s).

[0210]

[0220] Regardless of which part or section of the mixing line is shut down, the maintained mixing line goes offline, and the mixing of the heavy oil feedstock of the catalyst precursor through that line stops. However, the other parallel mixing lines remain online and continue to mix the diluent precursor mixture with at least 75% of the heavy oil feedstock to form the adjusted feedstock, and 25% or less of the remaining feedstock is diverted through the bypass line and recombines with the adjusted feedstock downstream of the remaining mixing lines. When one parallel mixing line is offline, the mixing efficiency may decrease, but since the mixing system of Example 5 can still prepare the adjusted feedstock that forms the dispersed metal sulfide catalyst particles in situ in the heavy oil feedstock, the overall mixing process is substantially improved compared to Comparative Example 1. Furthermore, the throughput and / or the liquid hourly space velocity can be easily maintained.

[0211]

[0221] Even if diverting a portion of the heavy oil feedstock through the bypass line during the maintenance period decreases the mixing efficiency of the entire mixing system, the decrease in the overall mixing efficiency can be partially or substantially alleviated by increasing the flow rate through the remaining mixing lines, subject to their capacity limits. This increases the mixing efficiency of each of the remaining mixing lines compared to when the flow rate through the mixing lines is maintained at approximately 25% of the total flow rate through the mixing system.

[0212]

[0222] For example, when operating parallel mixing lines, each mixing line can be operated to mix a dilution catalyst precursor mixture into approximately 25% of the total volume of the heavy oil feedstock flowing through the mixing system. However, if one of the parallel mixing lines is shut down for maintenance, the remaining mixing lines can be temporarily operated at a higher flow rate, subject to their capacity limits, to mix the dilution precursor mixture with a larger volume of the heavy oil feedstock, e.g., in a combined volume that is approximately 77%, 80%, 83%, 86%, 89%, 92%, or 95% of the total volume of the heavy oil feedstock flowing through the mixing system, and the remainder of the heavy oil feedstock (approximately 23%, 20%, 17%, 14%, 11%, 8%, or 5% respectively of the total) flows through a bypass line to maintain the same overall throughput of heavy oil through the mixing system and / or the same liquid hourly space velocity of heavy oil through the hydrotreating reactor.

[0213]

[0223] The present invention can be implemented in other specific forms without departing from the gist or essential characteristics thereof. The described embodiments should be considered in all respects only as illustrative and not restrictive. Accordingly, the scope of the present invention is indicated not by the above description but by the appended claims. All modifications within the meaning and equivalent scope of the claims are included within this scope.

Claims

1. 1. A method for mixing a catalyst precursor into heavy oil, comprising: blending a quantity of catalyst precursor with a quantity of diluent to form a diluted precursor mixture; mixing the diluted precursor mixture with a heavy oil feedstock using a plurality of parallel mixing lines, each parallel mixing line including one or more mixers and at least one valve for adjusting flow in the mixing line, to form a plurality of regulated feedstock streams; combining the conditioned feed streams in a common discharge line downstream from the parallel mixing lines to form a common conditioned feed stream; stopping flow through a blending line and causing or allowing a portion of the heavy oil feedstock to enter a bypass line, bypass the parallel blending lines, and be combined with the common conditioned feedstream at the common discharge line; continuing to mix at least a portion of the diluted precursor mixture with a remainder of the heavy oil feedstock using at least one other of the parallel mixing lines while a portion of the heavy oil feedstock passes through the bypass line.

2. The method of claim 1 , wherein the parallel mixing lines comprise two or more parallel mixing lines.

3. The method of claim 1 , wherein the parallel mixing lines comprise three or more parallel mixing lines.

4. 10. The method of claim 1, wherein each parallel mixing line comprises a high shear mixer and, optionally, a static in-line mixer and / or a strainer.

5. The method of claim 1 , wherein stopping flow through the mixing line comprises closing one or more valves in the mixing line to perform maintenance on the mixing line.

6. 10. The method of claim 1, wherein partially closing one or more valves associated with one or more operational parallel mixing lines and / or the common discharge line causes a portion of the heavy oil feedstock to enter the bypass line, bypass the parallel mixing lines, and combine with the common conditioned feedstock stream in the common discharge line to restrict flow and / or increase upstream pressure.

7. 10. The method of claim 1, further comprising mixing the same or similar amount of the diluted precursor mixture with the remaining portion of the heavy oil feedstock when one of the mixing lines is closed and a portion of the heavy oil feedstock bypasses the mixing line and is recombined with the common conditioned feedstock stream at the common discharge line.

8. 10. The method of claim 1, further comprising measuring a flow rate through the common exhaust line using a first flow meter and measuring a flow rate through the bypass line using a second flow meter.

9. The method of claim 1 further comprising measuring the flow rate through each parallel mixing line using a corresponding flow meter associated with the parallel mixing line.

10. 10. The method of claim 1, further comprising adjusting a flow rate through one or more parallel mixing lines, the common discharge line, or the bypass line by adjusting one or more valves associated with the parallel mixing lines, the common discharge line, or the bypass line.

11. The method of claim 1 further comprising using a portion of the heavy oil feedstock as a diluent to form the diluted precursor mixture.

12. 10. The method of claim 1, further comprising introducing the common conditioned feed stream from the common discharge line and any heavy oil feedstock from the bypass line to a surge tank, the surge tank causing or allowing further mixing of the catalyst precursor throughout the heavy oil feedstock.

13. 13. The method of claim 12, further comprising using a portion of the conditioned feedstock from the surge tank as a diluent to form the diluted precursor mixture.

14. 10. The method of claim 1, further comprising heating the conditioned feedstock downstream from the common discharge line to decompose the catalyst precursor and form dispersed metal sulfide catalyst particles throughout the heavy oil feedstock.

15. 10. The method of claim 1, further comprising causing or enabling the catalyst precursor to form in situ within the heavy oil feedstock dispersed metal sulfide catalyst particles that promote beneficial upgrading reactions, and hydrotreating the heavy oil feedstock at hydrotreating conditions to form converted products.

16. 16. The method of claim 15, wherein the hydrotreating is accomplished by at least one hydrotreating reactor selected from a slurry phase reactor, an ebullated bed reactor, and a fixed bed reactor.

17. 15. The method of claim 14, wherein the dispersed metal sulfide catalyst particles are less than 1 μm in size, less than about 500 nm in size, less than about 250 nm in size, less than about 100 nm in size, less than about 50 nm in size, less than about 25 nm in size, or less than about 10 nm in size.

18. A system for mixing a catalyst precursor into heavy oil, the system comprising means for carrying out the method of any one of claims 1 to 17.

19. 1. A system for mixing a catalyst precursor into heavy oil, comprising: at least one mixer configured to receive and blend a quantity of catalyst precursor with a quantity of diluent to form a diluted precursor mixture; a plurality of parallel mixing lines configured to receive the diluted precursor mixture and mix it with a heavy oil feedstock to form a plurality of regulated feedstock streams, each parallel mixing line including one or more mixers and at least one valve for modulating flow in the mixing line; a common discharge line configured to receive and combine the conditioned feed streams from the parallel mixing lines to form a common conditioned feed stream; a bypass line configured to receive a portion of the heavy oil feedstock when flow through at least one of the parallel mixing lines is stopped, cause the portion of the heavy oil feedstock to bypass the parallel mixing lines, and combine the bypassed portion of the heavy oil feedstock with the common conditioned feed stream at the common discharge line; wherein the system is configured such that when one of the mixing lines is closed and a portion of the heavy oil feedstock passes through a bypass line, a remaining portion of the heavy feedstock continues to be mixed with the diluted precursor mixture by at least one other of the parallel mixing lines.

20. 20. The system of claim 19, wherein the parallel mixing lines include at least two, e.g., three or four, parallel mixing lines.

21. 20. The system of claim 19, wherein each parallel mixing line includes a high shear mixer and, optionally, a static in-line mixer and / or a strainer.

22. 20. The system of claim 19, wherein each parallel mixing line includes one or more valves configured to be closed to stop flow through the mixing line to allow maintenance on the mixing line and / or partially closed to moderate flow through the mixing line.

23. 20. The system of claim 19, further comprising one or more valves associated with the parallel mixing line and / or the common discharge line and configured to restrict flow and / or increase upstream pressure to cause a portion of the heavy oil feedstock to enter the bypass line, bypass the parallel mixing line, and enter the common discharge line.

24. 20. The system of claim 19, further comprising a first flow meter associated with the common exhaust line and a second flow meter associated with the bypass line.

25. 25. The system of claim 24, further comprising a flow meter associated with each of the parallel mixing lines.

26. 20. The system of claim 19, further comprising one or more valves associated with the common exhaust line and the bypass line for regulating flow volume through the bypass line and the common exhaust line.

27. 20. The system of claim 19, further comprising a surge tank configured to receive the common conditioned feed stream from the common discharge line and any heavy oil feedstock from the bypass line, and to cause or allow further mixing of the catalyst precursor throughout the heavy oil feedstock.

28. 20. The system of claim 19, further comprising a blending line configured to provide a portion of the heavy oil feed stream as a diluent to form the diluted precursor mixture.

29. 20. The system of claim 19, further comprising a recycle line configured to provide heavy oil feedstock from the bypass line as a portion of the common conditioned feedstock stream and optionally as a diluent to form the diluted precursor mixture.

30. 20. The system of claim 19, further comprising a heater downstream from said common discharge line configured to heat said common conditioned feed stream to decompose said catalyst precursor and form dispersed metal sulfide catalyst particles in situ within said heavy oil feedstock.

31. 20. The system of claim 19, further comprising one or more hydrotreating reactors configured to receive and hydrotreat the heavy oil feedstock at hydrotreating conditions to form a converted product, wherein dispersed metal sulfide catalyst particles formed in situ from the catalyst precursor promote beneficial upgrading reactions.

32. 32. The system of claim 31, wherein the one or more hydroprocessing reactors are selected from a slurry phase reactor, an ebullated bed reactor, a fixed bed reactor, and combinations thereof.

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