Systems and methods for hydrotreating high chloride feedstocks

Abstract

A system for hydrotreating a hydrocarbon feedstock has a first stage including one or more first reactors capable of receiving the hydrocarbon feedstock and converting the hydrocarbon feedstock into an intermediate product. The feedstock has a total chlorine (Cl) content greater than 3 parts per million by weight (ppmw), and the intermediate product includes hydrogen chloride (HCl), ammonia (NH), and ammonium salts. The system also includes a heating system having a plurality of heat exchangers arranged in a loop and a heat transfer fluid capable of recovering and distributing heat to one or more fluids in the first stage. At least one heat exchanger of the plurality of heat exchangers is disposed between the first stage and the separation section, and the at least one heat exchanger is capable of maintaining a temperature of the intermediate product above the sublimation temperature of ammonia and hydrogen halide.

Description

[Technical Field]

[0001] This disclosure relates generally to the processing of high chloride (e.g., greater than 3 ppmw chlorine) feedstocks. More specifically, this disclosure relates to hydrotreating systems and processes that mitigate sublimation of ammonia and hydrogen halides from nitrogen and halogen species present in high chloride feedstocks. [Background technology]

[0002] Hydroprocessing systems are generally used to refine unrefined feedstocks (e.g., fossil fuels, bio-based feedstocks, municipal waste-derived feedstocks, solid plastic waste-derived feedstocks, and combinations thereof) into chemicals and fuels. With the increasing desire to develop alternative fuels and carbon cycles, hydroprocessing is an attractive technology for converting hydrocarbons from various sources into chemicals that can be used to create high-quality fuels and other products used as energy sources. Hydroprocessing includes hydrogenation, hydrodeoxygenation, hydrotreating, hydrocracking, and other reactions that chemically convert hydrocarbons in a feedstock into more desirable hydrocarbons (e.g., chemicals and / or fuels) in the presence of a catalyst.

[0003] Certain feedstocks used in hydrotreating contain contaminants (e.g., metals, non-metals, halogens, etc.) that can undesirably affect system components (e.g., metallurgy), catalyst performance, and process conditions, reducing system and process efficiency and increasing overall operating costs. Existing techniques used to remove contaminants, particularly chlorides, include water washing, caustic treatment, and solvent extraction. However, such techniques primarily remove water-soluble chlorides (e.g., sodium chloride (NaCl), potassium chloride (KCl)) and only a portion of the organic chlorides. Therefore, during hydrotreating, residual chlorides are converted to hydrogen chloride (HCl). As a result, the resulting hydrocarbon effluent stream produced during hydrotreating may still contain undesirable amounts of chloride in the form of HCl. Not only can HCl contaminate system metallurgy (e.g., due to corrosion), but HCl can also react with ammonia produced from nitrogen (N)-containing feed compounds to form ammonium chloride salts in the hydrocarbon effluent stream. These ammonium chloride salts can form undesirable deposits along the flow lines of the fluid circuit, which can have undesirable effects on the system metallurgy and the overall hydrotreating process. Therefore, there is an existing need to develop processes and systems that remove HCl formed from chlorides in hydrocarbon effluent streams in a manner that does not result in corrosion of the system metallurgy and deposition of chloride salts. Summary of the Invention

[0004] In one embodiment, a system for hydrotreating a hydrocarbon feedstock has a first stage including one or more first reactors capable of receiving a hydrocarbon feedstock and converting the hydrocarbon feedstock to an intermediate product. The feedstock has a total chlorine (Cl) content greater than 3 parts per million by weight (ppmw), and the intermediate product includes hydrogen chloride (HCl), ammonia (NH), and ammonium salts. The system also includes a heating system having a plurality of heat exchangers arranged in a loop and a heat transfer fluid capable of recovering and distributing heat to one or more fluids in the first stage. At least one heat exchanger of the plurality of heat exchangers is disposed between the first stage and the separation section, and the at least one heat exchanger is capable of maintaining a temperature of the intermediate product above the sublimation temperature of ammonia and hydrogen halide.

[0005] In another embodiment, a process for hydrotreating a hydrocarbon feedstock includes feeding the feedstock to a first stage of a hydrotreating system. The first stage has one or more reactors and can convert the hydrocarbon feedstock into an intermediate product having hydrogen chloride (HCl), ammonia (NH), and ammonium salts, where the hydrocarbon feedstock has a total chlorine (Cl) content greater than 3 parts per million by weight (ppmw). The process also includes cooling the intermediate product through a first heat exchanger disposed between the first stage and a separation section of the hydrotreating system to produce a cooled intermediate product. The first heat exchanger includes a heat transfer fluid capable of recovering heat from the intermediate product, and the temperature of the cooled intermediate product is above a precipitation temperature of the ammonium salts.

[0006] In a further embodiment, a process for hydrotreating a hydrocarbon feedstock includes cooling a hydrocarbon product having a first temperature through a first heat exchanger disposed between a first stage and a second stage of a hydrotreating system to produce a cooled hydrocarbon product, the hydrocarbon product being discharged from a hydrotreater and comprising hydrogen chloride (HCl), ammonia (NH), and ammonium salts, the first heat exchanger comprising a heat transfer fluid capable of recovering heat from the hydrocarbon product and producing a cooled hydrocarbon product having a second temperature, the second temperature being less than the first temperature and greater than a precipitation temperature of the ammonium salts.

[0007] Additional features and advantages of exemplary implementations of the present disclosure will be set forth in the description that follows, and in part will be obvious from the description, or may be learned by the practice of such exemplary implementations. The features and advantages of such implementations may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features will become more fully apparent from the following description and the appended claims, or may be learned by the practice of the exemplary implementations described hereinafter. [Brief explanation of the drawings]

[0008] Advantages of the present disclosure may become apparent upon reading the following detailed description and upon reference to the drawings. [Figure 1] 1 is a plot showing the sublimation curves of various ammonium salts. [Figure 2] FIG. 1 is a block diagram of a system for hydroprocessing a high chloride feedstock including a heating system having multiple heat exchangers arranged in a heat transfer loop utilizing a heat transfer fluid to distribute and recover heat throughout the process in accordance with an embodiment of the present disclosure. [Figure 3] 2 is a block diagram of the heating system of FIG. 1, wherein the heating system includes multiple heat exchangers on a loop in accordance with an embodiment of the present disclosure. [Figure 4]FIG. 2 is a process flow diagram for hydrotreating a chloride-rich feedstock using the system of FIG. 1 in accordance with an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] One or more specific embodiments of the present disclosure are described below. The described embodiments are examples of the technology of the present disclosure. Moreover, in an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described herein. It should be understood that, as in any engineering or design project, the development of any such actual implementation will involve numerous implementation-specific decisions to achieve the developer's particular goals, including compliance with system- and business-related constraints, which may vary from implementation to implementation. It should also be understood that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill in the art having the benefit of this disclosure.

[0010] When introducing elements of various embodiments of the present disclosure, the articles "a," "an," and "the" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. In addition, it should be understood that references to "one embodiment" or "embodiments" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0011] As used herein, the terms "approximately," "about," and "substantially" refer to an amount close to the stated amount that still performs the desired function or achieves the desired result. For example, the terms "approximately," "about," and "substantially" can refer to an amount that is within less than 10%, less than 5%, less than 1%, less than 0.1%, and less than 0.01% of the stated amount.

[0012] During hydroprocessing, the feedstock undergoes primary hydrotreating to produce a primary liquid product stream having a wide boiling range (e.g., approximately 20 degrees Celsius (°C) to 750°C), as well as a gas stream. The liquid product stream may contain hydrocarbons spanning a wide boiling range (e.g., the boiling ranges of naphtha, diesel, gas oil, and hydrowax), which can be further distilled into individual fractions or processed directly in a steam cracker, hydrocracker, or fluid catalytic cracker (FCC) to produce high-value chemicals and / or fuels. For example, the hydrotreating feedstock can be used to produce ethylene, propylene, and / or butylene, which are monomers that can be used as building blocks for new plastics. The feedstock can be derived from fossils, biomass, post-consumer products (e.g., solid plastic waste (SPW), municipal solid waste (MSW), etc.).

[0013] However, feedstocks also contain impurities that affect the efficiency and effectiveness of hydrotreating. For example, feedstocks contain components such as halogens, metals, and other non-carbonaceous molecules, which can cause equipment fouling and corrosion and / or inactivate catalysts used throughout the process. In particular, feedstocks may contain contaminants such as chlorides, metalloids such as silicon (Si) and arsenic (As), and metals such as nickel (Ni), vanadium (V), and sodium (Na). These contaminants can deactivate / poison catalysts used in hydrotreating and / or result in undesirable reactions and by-products, which not only foul downstream equipment but also reduce the efficiency and yield of the process. For example, in the case of chlorides, chlorides react with ammonia produced from nitrogen-containing feed compounds to convert to hydrogen chloride, forming ammonium chloride salts. Ammonium chloride salts can deposit on surfaces in hydrotreating systems, thereby fouling and / or clogging the equipment.

[0014] Several techniques exist for addressing chlorides and other contaminants present in feedstocks used in hydroprocessing applications. One technique for reducing the contaminant levels in these feedstocks is to blend a portion of the feedstock with naphtha or hydrowax sourced from conventional virgin crude oil refining. This mixture is coprocessed in a cracker unit to produce smaller molecules used to form new chemicals. The amount of feedstock in the mixture is such that the contaminant levels in the mixture are within the contaminant level requirements of the cracker unit. However, while this technique achieves the contaminant level requirements for the cracker, it simply dilutes the feedstock with naphtha / hydrowax. Therefore, only a small amount of feedstock may be processed in the cracker unit at a given time. However, as demand for alternative fuels and carbon recycling increases, the volume of diluent sourced from conventional, unprocessed crude oil may need to increase proportionately to meet the contaminant level limits of the cracker, making this technique inefficient and economically unattractive from the perspective of reducing demand for crude-oil-based products.

[0015] Another technique involves injecting amines upstream of the hydrotreater to convert inorganic chloride components to ammonium chloride salts, which can be removed through a water wash process. However, this technique effectively addresses only inorganic chlorides, which account for a relatively small percentage (e.g., less than approximately 10%) of the total chlorides found in some feedstocks. In hydrotreaters, even organic feed chlorides are converted to hydrogen chloride (HCl). Ammonia (NH3) can also be formed in hydroprocessing systems (e.g., in hydrotreaters) from the chemical reaction of nitrogen compounds present in the raw feed with hydrogen. Under certain system conditions (e.g., temperature and partial vapor pressure of HCl and NH3), ammonia and hydrogen chloride can sublimate from the vapor phase and deposit as solid ammonium chloride (NH4Cl) on system components (e.g., fluid flow circuits, inlets, etc.). For example, when the hydrotreater effluent stream is cooled from the temperature required in the hydrotreater to a low temperature (e.g., 50°C) close to ambient temperature, NH4Cl salts form and can deposit within the system circuits, causing fouling and blockage.

[0016] FIG. 1 is a plot 10 illustrating the mass action terms of NH and HCl as a function of temperature 14. As shown in plot 10, the deposition temperature of NHCl salt 16 increases with the partial pressures of HCl and NH in, for example, the hydrotreater effluent stream. For example, if the product of the partial pressures of HCl and NH in the hydrotreater effluent stream at a locally prevailing system temperature, T, (also referred to as the mass action term, K), is higher than the value 18 on the NHCl equilibrium line 16 at that same temperature, T, deposition of ammonium chloride salts can occur on system components. That is, if the mass action terms of NH and HCl are above the NHCl equilibrium line 16 for any given temperature (e.g., anywhere in region 20), ammonium chloride and hydrogen chloride will sublimate, resulting in undesirable deposition on system components. Furthermore, the same system temperature, T, may be too high (i.e., above the water dew point temperature) to inject a reasonable volume of wash water to obtain any fraction remaining as liquid water after evaporation. Liquid water dissolves ammonium salt precursors (e.g., NH3 and HCl). Therefore, when most of the wash water injected into the system evaporates, there is essentially no liquid water to dissolve the ammonium salt precursors. Therefore, these precursors cannot be separated from the hydrotreater effluent stream, and they will sublimate, thereby causing contamination / corrosion of system components. While this can be improved by increasing the volume of the wash water, it results in significant operational disadvantages (e.g., increased capital costs due in part to larger injection pumps and water recovery systems) and reduced potential for useful heat recovery from the reactor effluent to cooler process (e.g., reactor feed) streams. Therefore, there is an existing need to develop more efficient techniques for removing or otherwise reducing chlorides and various other contaminants or classes of contaminants present in hydrotreater effluent streams to mitigate the undesirable effects caused by the deposition of halide salts (e.g., ammonium chloride) on the hydrotreater.

[0017] Notably, for a given mass action value, the sublimation temperature (ST) of NH4Cl exceeds that of NHF and is significantly higher than that of ammonium sulfide (NH4HS). When the chlorine content of the feed exceeds 3 ppmw, the ST of NH4Cl generally becomes the highest and dominates among all STs of the ammonium salts. Thus, for Cl above 3 ppmw in the feed, if sublimation of ammonia and hydrogen chloride is prevented, precipitation of other ammonium salts, such as NHF and NH4HS, is also generally avoided.

[0018] Accordingly, disclosed herein are systems and methods including a heating system having multiple heat exchangers arranged in a loop that distributes and recovers heat within a system for hydrotreating high-chloride feedstocks (e.g., feedstocks having 3 ppmw Cl or greater) in a manner that mitigates the deposition of ammonium chloride salts in the hydrotreater. As discussed in more detail below, the disclosed heating system controls the temperature of the hydrotreater effluent stream so that, when cooled, its temperature remains above the ammonium chloride deposition temperature. In addition, the disclosed heating system avoids the formation of cold spots (below the ammonium chloride deposition temperature) along the fluid circuit that exist when using conventional feed / effluent heat exchange schemes. By using the disclosed systems and methods, the total chloride in the hydrotreater effluent stream can be dissolved in wash water without depositing chloride salts in the hydrotreating system. Furthermore, heat input and generated during hydrotreating can be recovered and transferred to other hydrotreating steps, thereby improving the energy efficiency of hydrotreating high-chloride feedstocks.

[0019] With the foregoing in mind, FIG. 2 is a block diagram of a system 100 used to hydrotreat high-chloride feedstocks, such as, for example, plastic-derived oils, fossil-derived feedstocks, bio-derived feedstocks, and combinations thereof. As used herein, a high-chloride feedstock is a feedstock having approximately 3 parts per million weight (ppmw) or more of Cl. System 100 may be part of a solid plastic waste (SPW) management plant or a refinery or chemical production plant. That is, system 100 may be integrated into a new or existing SPW management plant, and / or chemical production plant, and / or refinery complex. In other embodiments, system 100 may be located at a separate, independent location from the SPW management plant, and / or chemical production plant, and / or refinery complex.

[0020] System 100 includes a pre-hydrotreating stage 116 and a hydrocracking stage 118, each having various components that process liquid and / or gas streams to produce high-value products (e.g., fuels, chemicals, etc.) within system 100. However, as will be appreciated, in certain embodiments, system 100 may include only a single stage (e.g., pre-hydrotreating stage 116). In certain embodiments, system 100 may include a pre-purification section upstream of pre-hydrotreating stage 116. The pre-purification section may remove certain undesirable components from the feed used in system 100. However, this removal may be only partial. In the illustrated embodiment, pre-hydrotreating stage 116 includes a pre-hydrotreating system 120 having a series of reactors that remove certain contaminants to varying degrees from feedstock 124 and convert them to intermediate product 126. For example, pre-hydrotreating system 120 includes a diolefins saturation reactor 130, a demetallization reactor 132, and a hydrotreater 138. Pre-hydrotreating system 120 also includes a first heat exchanger 140 (e.g., an indirect heat exchanger) that uses heat recovered from system 100 to preheat diolefins saturation reactor effluent 142, as discussed in more detail below. Reactors 130, 132, and hydrotreater 138 may be in a single reactor or in separate reactors, and may be positioned in series and / or parallel.

[0021] The feedstock 124 can be any high-chloride feedstock (e.g., a feedstock having greater than 3 parts per million by weight (ppmw) Cl) derived from SPW, fossil fuels, biomass, or a combination thereof. In embodiments where the feedstock 124 is derived from SPW, the SPW undergoes a primary conversion process, such as, but not limited to, pyrolysis, hydropyrolysis, hydrothermal liquefaction, or hydrocracking, to produce a liquid stream. The feedstock 124 produced from the SPW can be a mixture of polymer fragments / oligomers (e.g., depolymerized polymers) and contaminants. In addition to high levels of chloride (e.g., greater than 3 ppmw Cl), the feedstock 124 can have other contaminants, such as, but not limited to, bromine (Br), fluorine (F), potassium (K), sodium (Na), phosphorus (P), and silicon (Si). Other contaminants include alkali metals (e.g., lithium (Li)), alkaline earth metals (e.g., calcium (Ca) and magnesium (Mg)), transition metals (e.g., nickel (Ni), vanadium (V), zinc (Zn), and iron (Fe)), and non-metals such as sulfur (S), nitrogen (N), and oxygen (O), which can undesirably affect catalyst activity, process efficiency, and equipment metallurgy. Therefore, these contaminants are removed or reduced from feedstock 124 during hydroprocessing (e.g., in the pretreatment section and / or reactor 132). Feedstock 124 also contains other components, such as diolefins, that may need to be removed / reduced (e.g., converted to olefins and paraffins) during hydroprocessing.

[0022] Within the hydrogenation pre-purification system 120, the feedstock 124 undergoes diolefin saturation, demetallization and / or desilication, deoxygenation, desulfurization, denitrification, and / or dechlorination. For example, during operation, the diolefin saturation reactor 130 receives the feedstock 124, where it undergoes selective hydrogenation in the presence of a hydrogenation catalyst and hydrogen (H). The selective hydrogenation catalyst can be any suitable hydrogenation catalyst, such as a Ni-based hydrogenation catalyst. As a non-limiting example, the Ni-based hydrogenation catalyst can be a NiMo catalyst supported on alumina. The selective hydrogenation converts diolefins (i.e., hydrocarbons with two conjugated double bonds) in the feedstock 124 to simpler olefins (i.e., hydrocarbons with a single double bond). To avoid complete hydrogenation of these olefins, and those already present in the feedstock 124, to form paraffins and the resulting undesirable temperature rise within the reactor, the diolefin saturation reactor 130 is maintained at an operating temperature range of approximately 100°C to approximately 200°C.

[0023] Following diolefin hydrogenation in diolefin saturation reactor 130, the resulting effluent stream 142 is fed to demetallization reactor 132 for removal of contaminants such as alkali metals (e.g., Li, Na, and K), alkaline earth metals (e.g., Mg and Ca), transition metals (e.g., Ni, V, Zn, and Fe), and nonmetals (e.g., P, As, and Si). Prior to feeding effluent stream 142 to demetallization reactor 132, stream 142 is preheated in heat exchanger 140. As previously discussed, the temperature of diolefin saturation reactor 130 is maintained in the range of approximately 100° C. to 200° C. to avoid complete hydrogenation of any olefins to paraffins. However, for demetallization of effluent stream 142, it is desirable for the effluent stream 142 to be at a temperature above 300° C. Thus, effluent stream 142 is heated in first heat exchanger 140 to a temperature in the range of approximately 300°C to approximately 375°C, depending on reactor conditions (e.g., start-up or end-of-run conditions), thereby producing preheated effluent stream 146.

[0024] The first heat exchanger 140 forms part of a heating system 148 of the system 100. As discussed in further detail below, the heating system 148 includes multiple heat exchangers (such as the first heat exchanger 140) arranged in a loop that circulates a heat transfer fluid (HTF) 144 that distributes and recovers heat from various steps in the hydrotreating process disclosed herein. The heat exchangers of the heating system 148 disclosed herein are indirect heat exchangers that utilize the HTF 144 to recover heat from certain effluent streams produced in the system 100 and distribute the recovered heat to other effluent streams produced in the system 100.

[0025] The demetallization reactor 132 may have one or more reactors each equipped with one or more guard beds that remove metal contaminants (e.g., Li, Na, K, Mg, Ca, Ni, V, Fe, and Zn) and non-metals (e.g., P, As, and Si) from the preheated effluent stream 146 in the presence of a demetallization catalyst and hydrogen. The demetallization catalyst may be any suitable catalyst that removes metals and non-metals, such as, but not limited to, Ni, V, Na, P, Si, and arsenic (As), from the preheated effluent stream 146. As a non-limiting example, the demetallization catalyst may be a nickel-based catalyst or combination, such as nickel molybdenum with or without phosphorus (NiMoP or NiMo). The NiMo / NiMoP catalyst hydrometallates metal-containing molecules, capturing and removing the metals from the preheated effluent stream 146 and producing the demetallized effluent stream 150. By removing contaminating metals from the preheated effluent stream 146, the activity of downstream catalysts used in system 100 may not be undesirably affected. For example, certain hydrorefining and / or hydrocracking catalysts may be sensitive to metal contaminants. These metal contaminants may reduce the activity of the hydrorefining and / or hydrocracking catalysts used in system 100, in part due to catalyst poisoning. The poisoned catalyst requires either removal or regeneration, resulting in reduced system efficiency and adding complexity to the process. However, by treating the preheated effluent stream 146 in the demetallization reactor 132, the undesirable effects of metal contaminants throughout the process may be mitigated. As will be appreciated, the demetallization catalyst in reactor 132 may convert chlorides from the preheated effluent stream 146 to hydrogen chloride.

[0026] Over time, the metal uptake capacity of the demetallization catalyst decreases. Therefore, the demetallization catalyst may need to be replaced with fresh or regenerated catalyst. Thus, in certain embodiments, the demetallization reactor 132 may include a series of reactors arranged in parallel so that one reactor remains on standby in case the demetallization catalyst in the other reactor needs to be replaced or regenerated. For example, if the metal uptake capacity of the catalyst in an operating reactor is below a desired level, that reactor may be taken offline and a standby reactor with fresh or regenerated catalyst may be brought online. Thus, system and process downtime is minimized.

[0027] Downstream of the demetallization reactor 132 is a hydrotreater 138. The hydrotreater 138 receives the demetallized effluent stream 150 and converts it to an upgraded liquid of suitable quality for cracking, for example, in a steam cracker or hydrocracker. For example, the hydrotreater 138 receives the demetallized effluent stream 150, where it undergoes hydrotreating in one or more hydrotreater reactors in the presence of one or more hydrotreater catalysts and hydrogen 152 at pressures ranging from approximately 30 barg to approximately 150 barg and temperatures ranging from approximately 100°C to 500°C. The hydrotreater 138 removes heteroatoms (e.g., sulfur (S), nitrogen (N), and oxygen (O)) and saturates olefins and aromatics through a series of hydrotreating reactions with hydrogen 152. In the illustrated embodiment, the hydrogen 152 is provided by a hydrogen manufacturing unit (HMU) 154. By way of non-limiting example, HMU 154 may be a steam methane reformer, or any other suitable HMU, or electrolyzer. In certain embodiments, a portion of hydrogen 152 may be recovered from system 100. For example, as shown in the illustrated embodiment, separation system 156 outputs a hydrogen-rich off-gas 159 that may be recycled to HMU 154 for hydrogen recovery.

[0028] In addition to removing heteroatoms from the demetallized effluent stream 150, the hydrotreating catalyst promotes saturation of at least a portion of the olefins and aromatics present in stream 150, thereby producing intermediate product 126. The hydrotreating catalyst system used in hydrotreating unit 138 can be any suitable hydrotreating catalyst or combination of hydrotreating catalysts having the desired activity in the temperature range of the disclosed hydrotreating process. For example, the hydrotreating catalyst can be selected from sulfided catalysts having one or more metals from the group consisting of Ni, Co, Mo, or W supported on a metal oxide. Suitable metal combinations include sulfided NiMo, sulfided CoMo, sulfided NiW, sulfided CoW, and sulfided trimetallic systems having any three metals consisting of Ni, Co, Mo, W, and a noble metal. Catalysts such as sulfided Mo, sulfided Ni, and sulfided W are also suitable for use. Oxide supports for sulfided metal catalysts include, but are not limited to, alumina, silica, titania, ceria, zirconia, and binary oxides such as silica-alumina, silica-titania, and ceria-zirconia, as well as combinations thereof. Preferred supports include alumina, silica, and titania. The support may optionally contain regenerated and reactivated fines of spent hydrorefining catalysts (e.g., fines of CoMo on oxide supports, fines of NiMo on oxide supports, and fines of hydrocracking catalysts containing NiW on a mixture of oxide supports and zeolites). The total metal loading on the catalyst ranges from approximately 5 wt. % to approximately 35 wt. % (expressed as the weight percentage of the calcined catalyst in oxide form, e.g., the weight percentage of nickel (as NiO) and molybdenum (as MoO) on a calcined NiMo oxide catalyst on an alumina catalyst). Additional elements, such as phosphorus (P), may be incorporated into the catalyst to improve metal dispersion. The metal may be introduced onto the support by impregnation or co-mulling, or a combination of both techniques.

[0029] The catalyst in hydrotreater 138 removes S, N, and O from stream 150 by converting these heteroatoms to hydrogen sulfide (HS), ammonia (NH), and water (HO), respectively. Stream 150 also contains (residual) chlorides. These chlorides in stream 150 are converted to hydrogen chloride (HCl) in hydrotreater 138. As will be discussed in more detail, HCl can form undesirable salts that can deposit on system surfaces, resulting in undesirable pressure drop and corrosion of system metallurgy.

[0030] The reaction occurring within the hydrotreater 138 is exothermic, causing the temperature of the intermediate product 126 to rise above 300°C. However, such a temperature is unsuitable for downstream processes. Therefore, the temperature of the intermediate product 126 must be reduced to below 250°C upstream of the separation system 156. Although a quench fluid (e.g., H gas) may be supplied to the hydrotreater 138 to control its operating temperature and therefore the temperature of the intermediate product 126, the temperature of the intermediate product may still exceed 250°C, which is unsuitable for the separation system 156. Due in part to the concentrations of HCl and NH3 in the intermediate product 126, reducing the temperature below 250°C can result in the precipitation of chloride salts, which is undesirable for system metallurgy. For example, in the presence of H2, HCl and NH3 form solid ammonium salts (e.g., ammonium chloride (NH4Cl)). Under certain system conditions (i.e., temperatures below approximately 250°C and pressures of 10,000,000 Pa), the intermediate product 126 may be heated to a temperature below 250°C. 2At temperatures exceeding 126 kJ / s (product of the partial vapor pressures of HCl and NH3), ammonia and hydrogen chloride may sublimate from the vapor phase and form solid deposits in system components (e.g., effluent lines, heat exchangers, reactors, etc.). Deposition of ammonium chloride on system components can result in equipment fouling and undesirable pressure drops. For example, precipitated ammonium chloride can foul heat exchangers, resulting in inefficient heat transfer. Heat exchanger piping and effluent lines can become clogged with precipitated ammonium chloride salt, further reducing heat transfer, causing undesirable pressure drops, and placing additional strain on the equipment to overcome the pressure drop. Additionally, ammonium chloride salt is hygroscopic and attracts water present in the intermediate product 126. This can result in wetting of the ammonium chloride salt and corrosion of the equipment. Furthermore, the high levels of total chloride (e.g., greater than 3 ppmw Cl) in certain feedstocks used in hydroprocessing, as well as the partial vapor pressures of HCl and NH in the intermediate product 126, are such that the temperature at which sublimation occurs may be at a level that precludes direct heat recovery to the low-temperature reactor feed, especially if cold spots exist throughout the heat exchanger piping, effluent lines, and other system components. Ammonium chloride can precipitate in cold-spot regions along the effluent flow, causing fouling of equipment components and undesirable pressure drop.

[0031] To mitigate the presence of cold spots and the deposition of ammonium chloride on system components, the system 100 disclosed herein includes a second heat exchanger 158 positioned downstream of the hydrotreater 138 and upstream of the hydrocracking stage 118. The second heat exchanger 158 forms part of a plurality of heat exchangers in the heating system 148. The second heat exchanger 158 recovers heat from the intermediate product 126 using the HTF 144 provided by the heating system 148 to produce a cooled intermediate product 160. The HTF 144 absorbs heat from the intermediate product 126, thereby cooling and lowering the overall temperature to below 300°C but above the sublimation temperature of the ammonia and hydrogen chloride present in the intermediate product 126. For example, the HTF 144 cools the intermediate product 126 to a temperature of approximately 250°C to 285°C. Unlike certain existing systems that use direct heat exchange with a cooled feedstock as a heat sink, the system disclosed herein uses the HTF 144 to not only cool the intermediate product 126 but also mitigate the presence of cold spots and / or low heat sink temperatures that can cause localized precipitation of ammonium chloride. The temperature of the HTF 144 at the inlet of the second heat exchanger 158 is controlled so that it exceeds the precipitation temperature of ammonium salts. The HTF 144 circulating through the loop of the heating system 148 is heated to a temperature above the precipitation temperature of ammonium salts before passing through the second heat exchanger 158 using heat recovered from the process of the system 100. In this way, ammonium chloride salts do not precipitate anywhere within the heat exchanger 158, which could clog the exchanger, reduce exchanger outlet pressure, and foul system components. By incorporating a second heat exchanger 158 downstream of the hydrotreater 138, the system 100 may be able to process high chloride feedstocks (e.g., feedstocks having greater than 3 ppmw Cl) without the need to remove chlorides upstream of the hydrotreater 138.

[0032] Second heat exchanger 158 recovers heat from intermediate product 126 to produce cooled intermediate product 160. The maximum amount of heat that can be recovered is limited because intermediate product 126 must not be cooled to a temperature below the precipitation temperature of ammonium salts (e.g., ammonium chloride) that may form in intermediate product 126. The resulting temperature of intermediate product 126 is still not low enough to allow further processing in separation system 156. For example, the maximum amount of heat recovered by HTF 144 in second heat exchanger 158 may be approximately 25% to 85% of the total heat input to the liquid feed (e.g., intermediate product 126), with the upper end of this range being achievable at lower sublimation temperatures (e.g., low feed chlorine and / or nitrogen content in intermediate product 126). However, in order for the cooled intermediate product 160 to undergo further processing downstream of the second heat exchanger 158, the cooled intermediate product 160 needs to be cooled to a temperature significantly lower than the precipitation temperature of ammonium chloride (e.g., a temperature in the range of 25-75°C). Therefore, to mitigate precipitation of ammonium chloride downstream of the second heat exchanger 158, the cooled intermediate product 160 is diluted and quenched using recycled wash water and hydrocarbon streams while lowering the temperature of the cooled intermediate product 160 to a temperature that is suitable for further processing in the separation system 156, thereby producing a diluted intermediate product 162.

[0033] For example, the wash water stream 164 produced in the separation system 156 is injected into the cooled intermediate product 160 upstream of the separation system 156. The wash water stream 164 dissolves and dilutes the HCl and NH in the cooled intermediate product 160, so that the concentration of these components in the vapor phase is at a level where sublimation of these components does not occur at lower temperatures (e.g., temperatures below 75°C). However, the cooled intermediate product 160 is still at a temperature above 250°C. Therefore, a portion of the wash water stream 164 injected into the cooled intermediate product 160 stream may vaporize. For example, approximately 45% to 90% of the injected wash water stream 164 may vaporize when contacted with the cooled intermediate product 160. The wash water stream 164 may be mixed with the hydrocarbon stream 170 produced in the separation system 156 to maintain at least approximately 25% to 80% of the injected wash water stream 164 in the liquid phase. Additionally, adding a portion of hydrocarbon stream 170 to cooled intermediate product 160 reduces the amount of wash water stream 164 required to maintain at least approximately 25% to 80% of the injected wash water stream 164 in the liquid phase. In the illustrated embodiment, streams 164 and 170 are each injected separately (concurrently or sequentially) into cooled intermediate product 160, although in other embodiments, stream 170 is mixed with wash water stream 164 before being injected into cooled intermediate product 160. In embodiments in which streams 164 and 170 are injected separately, hydrocarbon stream 170 may be added first to quench cooled intermediate stream 160, followed by injection of wash water stream 164 to dilute cooled intermediate product 160 and maintain ammonium chloride and other salts in solution.

[0034] The wash water stream 164 may include recycled water from the separation system 158, fresh make-up water from a make-up water tank, or both. The amount of wash water stream 164 injected into the cooled intermediate product 160 depends on the chloride (e.g., HCl) and ammonia (NH) concentrations in the cooled intermediate product 160, the nitrogen content of the feedstock 124, and the pH of the wash water stream 164. In certain embodiments, if the pH of the recycled wash water stream 164 is below a desired pH (e.g., an acidic pH), ammonia-treated fresh water may be injected into the wash water stream 164 to maintain the pH within a desired range of 6 to 7. The hydrocarbon stream 170 may be the condensed and separated hydrocarbon liquids produced in the separation system 156.

[0035] The resulting diluted and water-washed intermediate product 162 is fed to separation system 156, where product 162 is separated into four product streams: an aqueous phase (e.g., recycled water stream 164), a hydrocarbon liquid product 174, a hydrogen (H)-enriched off-gas 159, and a recycled gas 176. The aqueous phase is used as wash water stream 164. In certain embodiments, a portion of the aqueous phase is sent as a bleed stream to a wash water recovery system external to system 10. In certain embodiments, diluted intermediate product 162 may be cooled in a cooler (e.g., an air cooler) before being fed to separation system 156. The cooler may further cool diluted intermediate product 162 to a temperature below 75° C. Because the HCl and NH in cooled and diluted intermediate product 162 are dissolved and diluted in the aqueous phase, sublimation of ammonia with hydrogen chloride or other hydrogen halides to form ammonium salts is not an issue. Furthermore, in separation system 156, the aqueous phase (comprising HCl and NH3) is separated and removed from the hydrocarbon liquid product 174 upstream of hydrocracking stage 118. Thus, the process in hydrocracking stage 118 is no longer undesirably affected by chlorides present in feedstock 124. Thus, unlike certain existing hydroprocessing systems, system 100 may be used to hydroprocess high chloride feedstocks, such as feedstock 124.

[0036] Separation system 156 includes one or more separators (e.g., a low-temperature, high-pressure separator, a low-temperature, low-pressure separator, a high-temperature, high-pressure separator, and a high-temperature, low-pressure separator) that separate the diluted intermediate product 162 into a wash water stream 164, a hydrocarbon liquid product 174, a hydrogen (H)-enriched off-gas 159, and a recycle gas 176. In certain embodiments, the diluted intermediate product 162 may be combined with another hydrocarbon stream produced in system 100 (e.g., a hydrocarbon stream produced in a downstream conversion unit such as a steam cracker or hydrocracker). The recycle gas 176 may be contacted with supplemental wash water (e.g., a portion of stream 164 and / or from a supplemental wash water drum) in separation system 156 to scrub or otherwise remove NH from the recycle gas 176 before being sent to a recycle gas compressor and utilized in the process of system 100.

[0037] The hydrocarbon liquid product 174 output from separation system 156 is fed to product recovery section 182. In product recovery section 182, hydrocarbon liquid product 174 may undergo distillation to separate into fractions according to the boiling point ranges of the hydrocarbons contained in hydrocarbon liquid product 174. For example, hydrocarbon liquid product 174 includes, among other things, naphtha range hydrocarbons 194 and hydrowax 200. Naphtha range hydrocarbons 194 may be fed to a naphtha steam cracker or a fluid catalytic cracker where they are converted to lower olefins, for example, for use in the production of new consumer plastic goods. The remaining fraction (e.g., hydrowax 200) may also be used in chemical production processes as feed to a heavy oil steam cracker or other processes to produce commercially viable products, such as fuels and other chemicals. In certain embodiments, hydrowax 200 may be recycled to hydrocracking reactor 202 of hydrocracking stage 118. The hydrocracker 202 converts the hydrowax 200 into additional naphtha range hydrocarbons. Optionally, in certain embodiments, the naphtha or heavy fraction may be recycled to the hydrotreating reactor 138 or other reactors (e.g., pre-refining reactors) within the system 100. The product recovery section 182 may also produce light gases 188 (e.g., C1-C4, NH3, HS, HO (e.g., steam), CO, and CO2) as by-products.

[0038] As previously discussed, the hydrowax 200 may be fed to the hydrocracking reactor 102 for further processing. The hydrocracking reactor 202 breaks down (i.e., cracks) the hydrocarbons in the hydrowax 200 in the presence of a hydrocracking catalyst and hydrogen 152 to form a hydrocracked (HC) intermediate product 204 having an increased portion of lighter hydrocarbons (e.g., C5-C9 hydrocarbons in the naphtha range) that is substantially free of oxygen, nitrogen, sulfur, metals, and halogens, and gases such as H2, CO, and CO2, among others. The hydrocracking reactor 202 operates at a pressure of approximately 50 barg to approximately 200 barg and a temperature in the range of approximately 275°C to 500°C. In certain embodiments, the temperature and pressure in the hydrocracking reactor 202 are substantially the same as in the hydrotreating reactor 138. Prior to entering the hydrocracking reactor 202, the hydrowax 200 is heated by a third heat exchanger 206 of the heating system 148. For example, the hydrowax 200 available from the product recovery section 182 at a temperature in the range of approximately 180-210°C may be heated by the HTF 144 to a temperature in the range of approximately 325-360°C.

[0039] The hydrocracking catalyst used in the hydrocracking reactor 202 can include any suitable hydrocracking catalyst having the desired activity in the temperature range of the disclosed hydrocracking process. For example, the hydrocracking catalyst can be selected from sulfided catalysts having one or more metals from the group consisting of Ni, Co, Mo, or W supported on a metal oxide. Suitable metal combinations include sulfided NiMo, sulfided CoMo, sulfided NiW, sulfided CoW, and sulfided trimetallic systems having any three metals from the family consisting of Ni, Co, Mo, and W. Catalysts such as noble metal zeolites, sulfided Mo, sulfided Ni, and sulfided W are also suitable for use. Metal oxide supports for sulfided metal catalysts include, but are not limited to, alumina, silica, titania, ceria, zirconia, and binary oxides of alumina and silica, either amorphous or having a defined structure, such as zeolite beta, X, or Y, silica-titania, and ceria-zirconia. Preferred supports include alumina, silica, and titania. The support may optionally contain regenerated and reactivated fines of spent hydrorefining catalysts (e.g., fines of CoMo on oxide supports, fines of NiMo on oxide supports, and fines of hydrocracking catalysts containing NiW on a mixture of oxide supports and zeolites). The total metal loading on the catalyst ranges from approximately 5 wt. % to approximately 35 wt. % (expressed as the weight percentage of the calcined catalyst in oxide form, e.g., the weight percentage of nickel (as NiO) and molybdenum (as MoO) on a calcined NiMo oxide catalyst on an alumina catalyst). Additional elements, such as phosphorus (P), may be incorporated into the catalyst to improve metal dispersion. The metals may be introduced onto the support by impregnation or co-mulling, or a combination of both techniques.

[0040] In certain embodiments, a portion of the hydrocracked intermediate product 204 is fed to separation system 156, where it undergoes a first high-temperature separation process in a gas-liquid separator that separates and removes, in either single or multiple steps, a vapor phase (e.g., H, C-C, and higher boiling hydrocarbons) from the hydrocarbon liquids in the hydrocracked product 204. Any suitable phase separation technique may be used to separate and remove the vapor from the hydrocarbon liquids. The resulting vapor phase may be combined with the cooled intermediate product 160 from pre-hydrotreatment system 120 for further condensation, cooling, and phase separation in separation system 156 to produce the hydrocarbon liquid product 174.

[0041] In certain embodiments, recycle gas 176 is fed to a gas cleaning system that removes H2S, NH3, CO2, and in certain embodiments, CO, and trace amounts of organic sulfur-containing compounds, if present, as process by-products, thereby producing a hydrogen-rich stream that can be recycled to hydropretreatment system 120 and / or hydrocracking reactor 202. The liquid hydrocarbon stream separated from hydrocracking product 204 forms part of hydrocarbon liquid product 174 that is sent to product recovery section 182.

[0042] System 100 may also include a controller 206 that manages the operation of system 100. Controller 206 may independently control the operation of system 100 by electronically communicating with sensors, control valves, pumps, and other flow regulation functions throughout system 100. Controller 206 may include a fully or partially automated distributed control system (DCS) or any computer-based workstation. For example, controller 206 may be any device employing a general-purpose or application-specific processor 208, both of which may include memory circuitry 210 for storing instructions such as system parameters (e.g., pretreatment conditions, hydrotreating conditions, hydrocracker conditions, heating system conditions, contaminant concentrations, sublimation temperature, pH, etc.). Processor 208 may include one or more processing devices, and memory circuitry 210 may include one or more tangible, non-transitory, machine-readable media that collectively store instructions executable by processor 208 to control the operations described herein.

[0043] In one embodiment, the controller 206 may operate control devices (e.g., valves, pumps, etc.) to control the amounts and / or flows between different system components. It should be noted that there may be valves throughout the system 100 that are used to regulate the different amounts and / or flows between the system components. For example, the controller 206 may also manage the operation of the valves to control the amounts or regulate the flows of the feedstock 124, intermediate products 126, 160, 162, streams 164, 170, 172, hydrocarbon liquid product 174, hydrocracked intermediate product 204, and hydrogen 152 that are supplied to the different components of the system 100. In certain embodiments, the controller 206 may use information provided via input signals to execute instructions or code contained on a machine-readable or computer-readable storage medium (e.g., memory circuit 210) and may generate one or more output signals 214 to various control devices (e.g., valves, pumps, etc.) for controlling the flow of fluids (e.g., feedstock 124, intermediate products 126, 160, 162, streams 164, 170, hydrocarbon liquid product 174, hydrocracked intermediate product 204, and hydrogen 152, or other suitable fluids) throughout the system 100.

[0044] As previously discussed, heating system 148 includes multiple heat exchangers (e.g., heat exchangers 140, 158, 206) that recover and transfer heat generated within system 100. Heat exchangers 140, 158, 206 of heating system 148 are indirect heat exchangers that utilize HTF 144 to recover and transfer heat generated within system 100 to various streams and system components. For example, FIG. 3 illustrates an embodiment of heating system 148 that may form part of system 100. Heating system 148 mitigates precipitation of ammonium chloride (NH4Cl) and other salts within system 100 by avoiding the formation of cold spots in the system flow circuit between pre-hydrogenation purification system 120 and separation system 156. Heating system 148 recovers heat from various products produced by system 100 (e.g., intermediate product 126) and transfers it reliably to other streams and / or system components (e.g., stream 142, hydrocracking reactor feed (hydrowax 200)). Heating system 148 also centralizes the heat requirements of system 100, thereby avoiding the use of multiple combustion or electric heaters.

[0045] In the embodiment illustrated in FIG. 3 , heating system 148 includes a fluid vessel 230 containing a volume of heat transfer fluid (HTF) 232 used to recover and transfer heat throughout system 100. HTF 232 can be any suitable heat transfer fluid, such as, for example, a mixture of biphenyl and diphenyl oxide (e.g., Dowtherm™ A or Therminol® VP-1), steam, etc. During operation, HTF 232 is routed (via a circulation pump) through heater 234, which heats HTF 232 to a temperature of 350° C. to 380° C. to produce heated transfer fluid 238. In one embodiment, heating of HTF 232 by heater 234 occurs only during start-up, before heat transfer fluid 232 recovers heat from the hydroprocessing system. After start-up, HTF 232 is maintained at a desired temperature using heat recovered from system 100. In certain embodiments, heater 234 can provide additional heat to HTF 232 if more heat is needed. Heater 234 may be any suitable heater, such as, for example, an electric heater.

[0046] Downstream of the heater 234, the heated transfer fluid 238 may be split into various streams that each pass through a respective heat exchanger 140, 206, 242, 246 positioned throughout the system 100. For example, a portion of the heated transfer fluid 238 may be directed to the first heat exchanger 140, which heats the effluent (e.g., the diolefin saturated effluent stream 142) in a first stage (e.g., the pre-hydrotreating stage 116) of a hydroprocessing system (e.g., the system 100). Another portion of the heated transfer fluid 238 may be directed to the third heat exchanger 206 in a second stage (e.g., the hydrocracking stage 118) of a hydroprocessing system (e.g., the system 100) to heat the hydrocarbon product (e.g., the hydrowax 200) produced in a product recovery system (e.g., the product recovery system 182). An additional portion of the heated transfer fluid 238 may be supplied to heat exchangers 242, 246 located within a hydroprocessing system (e.g., system 100). For example, the heat exchangers 242, 246 may be located within the product recovery section 182. These heat exchangers 242, 246 may heat various streams produced within the product recovery section 182. For example, the product recovery section 182 may be configured to heat heavy hydrocarbons (e.g., C 1 ) in a liquid stream (e.g., hydrocarbon liquid product 174). 4+ The distillation system may include one or more distillation columns (e.g., a stabilization column and a separation column) that separate light hydrocarbons (e.g., C4 and lighter) from the crude oil. A heated heat transfer fluid 238 circulating through heat exchangers 242, 246 provides heat (i.e., transfers heat) to a reboiled liquid that is recycled to the distillation columns.

[0047] After the heated transfer fluid 238 transfers heat to the fluid passing through the heat exchangers 140, 206, 242, 246, thereby heating the process fluid, each respective heat exchanger 140, 206, 242, 246 discharges a cooled heat transfer fluid 250, 250'. The cooled heat transfer fluid 250, 250' may be at a temperature in the range of approximately 200°C to 275°C. The cooled heat transfer fluid 250 is directed to the second heat exchanger 158. For example, as discussed above with reference to FIG. 2, the second heat exchanger 158 removes heat from the HT product 126. Thus, while in the second heat exchanger 158, the cooled heat transfer fluid 250 absorbs heat from the intermediate product, thereby cooling the intermediate product and generating a second (re)heated transfer fluid 254. The second heated transfer fluid 254 may be at a temperature in the range of approximately 300°C to 350°C. The second heated transfer fluid 254 may be supplied to the fluid reservoir 130 and recirculated through the heating system 148 .

[0048] The cooled heat transfer fluid 250' is returned to the fluid reservoir 230 and recirculated throughout the heating system 148. In certain embodiments, a portion of the first heated transfer fluid 238 may bypass the heat exchangers 140, 206, 242, 246 and mix with the cooled transfer fluid 250 upstream of the fluid reservoir 230, thereby producing a third heated transfer fluid 256. This may help maintain the heat transfer fluid 232 in the fluid reservoir 230 at a desired temperature (e.g., a temperature in the range of 350°C to 380°C). The heating system 148 may also include a cooler 260 (e.g., an air cooler). The cooler 260 may receive the heat transfer fluid 232 from the fluid reservoir 230 and cool it to a desired temperature to produce a cooled fluid 262. Depending on the temperature of the transfer fluid 250, the cooled fluid 262 may be injected into the stream of transfer fluid 250 to adjust (lower) its temperature. For example, if the temperature of the cooled heat transfer fluid 250 exceeds a desired temperature that allows for maximum heat recovery from the intermediate product (e.g., intermediate product 126), the heating system 148 may add cooled fluid 262 to the cooled heat transfer fluid 250 to reduce the temperature of the cooled heat transfer fluid 250 to the desired temperature.

[0049] The optimal temperature of the cooled heat transfer fluid 250 going to the second heat exchanger 158 is a trade-off between maintaining a safety margin above the estimated sublimation temperature in the intermediate product 126 (i.e., increasing the HTF feed temperature to the second heat exchanger 158) and maximizing the temperature difference between the intermediate product 126 and the HTF feed to the second heat exchanger 158 (reducing the HTF feed temperature) for maximum heat recovery. The chiller 260, included to allow for start-up of the heating system 148 without heat already being needed within the hydroprocessing system 10, allows for establishing this optimal temperature for the heat exchanger 158.

[0050] The heating system 148 may also include a replenishment drum 268. The replenishment drum 268 may be used to store HTF 232 that is not circulated throughout the heating system 148. If the fluid level of HTF 232 in the fluid container 230 drops below a desired level (e.g., if the liquid inventory of the heating system 148 contracts at a lower temperature), the replenishment drum 268 may supply HTF 232 to the fluid container 230 to increase the fluid level. Conversely, if the fluid level of HTF 232 in the fluid container 230 rises above a desired level (higher temperatures cause thermal expansion of the liquid inventory), excess HTF 232 may bleed into the replenishment drum 268.

[0051] Heating system 148 includes valves for controlling the flow of fluids 232, 238, 250, 250', 254, 256, 262 throughout the various heat exchangers and other components of heating system 148. Additionally, heating system 148 includes pressure and temperature sensors throughout for controlling the pressure and temperature, respectively, of fluids 232, 238, 250, 250', 252, 254, 256, 262 within heating system 148. The valves and sensors of heating system 148 are controlled by a controller (e.g., controller 206).

[0052] In another embodiment of the heating system 148, steam generation from external boiler feed water (BFW) is used to recover heat from the intermediate product 126. By manipulating the saturation pressure of the generated steam, the minimum temperature to which the intermediate product 126 is exposed in the second heat exchanger 158 can be precisely controlled. This avoids the formation of cold spots in the system flow circuit between the pre-hydropurification system 120 and the separation system 156 and effectively reduces the deposition of ammonium chloride (NH4Cl) and other salts in this system. Preheating of the BFW can be performed by condensing external utility steam with a higher saturation pressure. The heat contained in the steam generated in the second heat exchanger 158 can be supplemented in part with additional external utility steam and advantageously distributed, for example, to the diolefins saturated effluent stream 142 in the heat exchanger 140 and / or to a suitable consumer of heat (e.g., product recovery section 182).

[0053] FIG. 4 is a flow diagram of a process 280 for hydrotreating a chloride-rich feedstock (e.g., a feedstock having greater than 3 ppmw Cl) using the system of FIG. 2. Process 280 includes a pre-hydrotreating step 284, a heat recovery step 292, and a quench, wash, and dilution step 294. The chloride-rich feedstock (e.g., chloride-rich feedstock 124) undergoes processing in pre-hydrotreating step 284, which selectively saturates diolefins (e.g., in diolefin saturation reactor 130) and demetallates them (e.g., in demetallation reactor 132), hydrotreating the chloride-rich feedstock to an intermediate product (e.g., intermediate product 126). Chloride in the feedstock is converted to HCl in the intermediate product. In addition to HCl, the intermediate product also contains nitrogen in the form of ammonia (NH). The concentrations of HCl and NH in the intermediate product are such that, upon cooling, ammonium salts (e.g., ammonium chloride) are formed and may precipitate on system components. The precipitated ammonium salts can cause undesirable contamination, blockages, and pressure drops throughout the system. To avoid ammonium salt precipitation, certain system components may be maintained at temperatures above the sublimation temperature of the salt precursor.

[0054] In heat recovery step 292, a heat exchanger (e.g., heat exchanger 158) cools the intermediate product by using a heat transfer fluid to recover a maximum amount of heat from the intermediate product while still maintaining the temperature of the resulting cooled intermediate product (e.g., cooled intermediate product 160) above the precipitation temperature of the ammonium salts. The heated heat transfer fluid (e.g., second heated transfer fluid 254) with the heat recovered from the intermediate product is fed back to the heating system and can be used to transfer heat to other fluids or system components throughout the hydroprocessing system. In addition to recovering heat from the intermediate product, the heat transfer fluid avoids the formation of cold spots in the fluid circuit by heating the heat exchanger to a temperature above the precipitation temperature of the ammonium salts.

[0055] The cooled intermediate product may still be at an undesirable temperature for further processing downstream of the pre-hydrotreating system. Therefore, the cooled intermediate product may require additional cooling in quenching and dilution step 294. To avoid precipitation of ammonium salts in the cooled intermediate product, a wash oil stream (e.g., hydrocarbon stream 170) produced in the separation system is added to the cooled intermediate product to quench and dilute it. In addition to the wash oil stream, a wash water stream (e.g., wash water stream 164) also produced in the separation system is added to the cooled intermediate product to further quench the cooled intermediate product and dissolve the ammonium salts, HCl, and NH3 to produce a diluted intermediate product (e.g., diluted intermediate product 162). Therefore, ammonium salts do not precipitate when the cooled intermediate product is further cooled to a temperature below the original sublimation temperature of the salt precursor. In this manner, the process 280 disclosed herein mitigates precipitation of ammonium salts in the chloride-rich feedstock downstream of the pre-hydrotreating system. Therefore, contaminants such as chlorides and nitrogen present in the feedstock may not need to be removed upstream of the hydrotreating pre-system.

[0056] A technical effect of hydrotreating high-chloride feedstocks using the systems and methods disclosed herein is the mitigation of the undesirable effects of precipitation of ammonium salts, such as ammonium chloride, on system component surfaces and / or inlets. Thus, systems used for hydrotreating can be used with high-chloride feedstocks without requiring complex pretreatment of these feedstocks to remove or reduce the amount of certain contaminants, such as chloride and nitrogen. Existing technologies utilize caustic washes and solvent extractions to remove or reduce the amount of chloride in high-chloride feedstocks that undergo hydrotreating upstream of hydrotreating pretreatment systems. Caustic washes remove only a portion of the chloride, while solvent extraction produces undesirable hydrocarbon waste streams that are highly aromatic and contain undesirable amounts of chloride. Therefore, disposal of these waste product streams can be difficult and expensive. However, by using the systems and methods disclosed herein, chlorides and other contaminants (e.g., NH3) can be removed downstream of the pre-hydrotreating system prior to conversion steps such as hydrocracking or steam cracking without the precipitation of ammonium salts (e.g., ammonium chloride), which can cause undesirable corrosion, equipment fouling, and / or plugging of system components. By using the heating system disclosed herein, the chloride-rich stream and system components can be maintained at temperatures above the precipitation temperature of ammonium salts, while also recovering heat from the chloride-rich stream that can be used elsewhere throughout the system. This improves the overall efficiency of the system and also reduces overall operating costs, as heat generated by the system can be recovered and reused. Additionally, certain effluent streams, such as those generated within the separation system, can be used to quench and dilute the chloride-rich stream. Thus, precipitation of ammonium salts is avoided even after the temperature of the chloride-rich stream drops below the sublimation temperature of the salt precursor. Thus, the disclosed systems and methods provide an effective, efficient, and robust technology for hydroprocessing of high chloride feedstocks derived from SPW, fossil, biomass, and combinations thereof.

[0057] The present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the present disclosure is, therefore, indicated by the appended claims rather than the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. 1. A system for hydroprocessing a hydrocarbon feedstock, comprising: a first stage comprising one or more first reactors configured to receive the hydrocarbon feedstock and convert the hydrocarbon feedstock into an intermediate product, the feedstock having a total chlorine (Cl) content greater than 3 parts per million by weight (ppmw), the intermediate product being a mixture of hydrogen halide, ammonia (NH ３ a first stage comprising: a heating system including a plurality of heat exchangers arranged in a loop having a heat transfer fluid configured to recover and distribute heat to one or more fluids in the first stage, at least one heat exchanger of the plurality of heat exchangers being disposed between the one or more first reactors and a separation section, the at least one heat exchanger being configured to maintain a temperature of the intermediate product above a sublimation temperature of ammonia and hydrogen halide.

2. The system of claim 1 , comprising a separation system disposed within the separation section and configured to receive the intermediate product and separate the intermediate product into an aqueous stream and a first hydrocarbon liquid.

3. 3. The system of claim 2, comprising: a first conduit extending between and fluidly connecting the first stage and the separation system; and a second conduit extending between and fluidly connecting the separation system and the first conduit, the second conduit configured to inject a quench fluid produced in the separation system into the first conduit downstream of the at least one heat exchanger of the plurality of heat exchangers, the first conduit containing the intermediate product.

4. 2. The system of claim 1, wherein the one or more first reactors comprise a diolefin saturation reactor, a demetallization reactor, and a hydrotreating reactor, the hydrotreating reactor configured to produce the intermediate product, and another heat exchanger of the plurality of heat exchangers is disposed between the diolefin saturation reactor and the demetallization reactor, the heat exchanger configured to transfer heat to an effluent with a reduced diolefin content produced in the diolefin saturation reactor.

5. The ammonium salt is ammonium chloride, ammonium disulfide, ammonium halide, or a combination thereof, the intermediate product contains hydrogen chloride (HCl), and the HCl and the NH ３ The product of the partial vapor pressures is 100,000 Pa. ２ The system of claim 1 .

6. 2. The system of claim 1, wherein the heating system includes a fluid vessel configured to contain the heat transfer fluid and a heater disposed between the fluid vessel and the at least one heat exchanger, the heater configured to heat the heat transfer fluid upstream of the at least one heat exchanger.

7. 10. The system of claim 1, wherein the feedstock is a liquid hydrocarbon derived from fossils, biomass, post-consumer products, solid plastic waste, and combinations thereof.

8. 10. The system of claim 1, comprising a second stage disposed downstream of and fluidly connected to the first stage, the second stage comprising one or more second reactors configured to receive a first hydrocarbon liquid product derived from the intermediate product and to produce a second hydrocarbon liquid product, the first hydrocarbon liquid and the second hydrocarbon liquid being substantially free of chlorides.

9. 1. A process for hydrotreating a hydrocarbon feedstock, comprising:

1. Supplying a feedstock to a first stage of a hydroprocessing system, said first stage comprising one or more reactors, said hydrocarbon feedstock being treated with a mixture of hydrogen halide, ammonia (NH ３ ), and an ammonium salt, and converting the hydrocarbon feedstock into an intermediate product having an ammonium salt, the hydrocarbon feedstock having a total chlorine (Cl) content greater than 3 parts per million by weight (ppmw); and cooling the intermediate product through a first heat exchanger disposed between the one or more reactors and a separation section of the hydroprocessing system to produce a cooled intermediate product, the first heat exchanger comprising a heat transfer fluid configured to recover heat from the intermediate product, and wherein the temperature of the cooled intermediate product is above a precipitation temperature of the ammonium salt.

10. 10. The process of claim 9, comprising quenching the cooled intermediate product to reduce the temperature below the precipitation temperature of the ammonium salt, wherein quenching the cooled intermediate product comprises injecting a quench fluid into the flow of the intermediate product, the quench fluid being generated in a separation system disposed within the separation section and fluidly connected to the first stage.

11. The ammonium salt is ammonium chloride, ammonium disulfide, ammonium halide, or a combination thereof, the intermediate product contains hydrogen chloride (HCl), and the HCl and the NH ３ The product of the partial vapor pressures is 100,000 Pa. ２ The process of claim 9 , wherein the

12. 10. The process of claim 9, wherein converting the hydrocarbon feedstock to the intermediate product comprises selectively saturating diolefins to produce a first effluent, demetallating the first effluent to produce a second demetallated effluent, and hydrotreating the second demetallated effluent to produce the intermediate product.

13. 13. The process of claim 12, wherein the first effluent is heated through a second heat exchanger containing the heat transfer fluid, the second heat exchanger being fluidly connected to the first heat exchanger in a loop configuration.

14. 10. The process of claim 9, wherein a first hydrocarbon liquid product is produced from the intermediate product in the separation section and the first hydrocarbon liquid product is fed to a second reactor comprising one or more second reactors configured to produce a second hydrocarbon liquid product from the first hydrocarbon liquid product, wherein the first hydrocarbon liquid and the second hydrocarbon liquid are substantially free of chlorides.

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