Heavy oil conversion with heavy oil hydrotreating recycle

Abstract

A process includes receiving, in a heavy oil hydrotreating unit, a solid-free lean stream containing unconverted oil processed from a heavy oil feedstock in a slurry hydroconversion reactor, hydrotreating the solid-free lean stream containing the unconverted oil in the presence of hydrogen and a hydrotreating catalyst in the heavy oil hydrotreating unit under heavy oil hydrotreating conditions, thereby producing a hydrotreated effluent, and recycling at least a portion of the hydrotreated effluent to the slurry hydroconversion reactor.

Description

PRIORITY CLAIM

[0001] The present application claims priority to U.S. Provisional Patent Application Ser. No. 63 / 710,217, entitled “Heavy Oil Conversion with Heavy Oil Hydrotreating Recycle,” filed Oct. 22, 2024, and to U.S. Provisional Patent Application Ser. No. 63 / 635,912, entitled “Achieve Full or Near Full Heavy Oil Conversion with Heavy Oil Hydrotreating Recycle,” filed Apr. 18, 2024, the content of each of which is incorporated by reference herein in their entirety.BACKGROUND

[0002] The petroleum industry is increasingly turning to heavy oil feedstocks such as heavy crudes, resids, coals, tar sands, etc., as sources for refining feedstocks for the manufacture of useful fuels. These feedstocks are characterized by high concentrations of asphaltenes having rich residues and low API gravities, with some being as low as less than 0° API.

[0003] 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.SUMMARY

[0004] In accordance with an illustrative embodiment, a process comprises:

[0005] receiving, in a heavy oil hydrotreating unit, a solid-free lean stream comprising unconverted oil processed from a heavy oil feedstock in a slurry hydroconversion reactor,

[0006] hydrotreating the solid-free lean stream comprising the unconverted oil in the presence of hydrogen and a hydrotreating catalyst in the heavy oil hydrotreating unit under heavy oil hydrotreating conditions, thereby producing a hydrotreated effluent, and

[0007] recycling at least a portion of the hydrotreated effluent to the slurry hydroconversion reactor.

[0008] In accordance with another illustrative embodiment, a process comprises:

[0009] exposing a heavy oil feedstock to a slurry hydroconversion catalyst under slurry hydroconversion conditions in a reaction zone of a slurry hydroconversion reactor in the presence of hydrogen, thereby producing a slurry hydroconversion effluent comprising a gas product and a slurry product comprising upgraded heavy oil, unconverted oil, solid catalyst particles and solids formed during a hydroconversion reaction,

[0010] separating the slurry product from the gas product of the slurry hydroconversion effluent, thereby producing a slurry stream comprising the unconverted oil, the solid catalyst particles and the solids formed during the hydroconversion reaction,

[0011] separating the upgraded heavy oil from the slurry stream of the slurry hydroconversion effluent using one or more solid-liquid separators, thereby producing a solid-free lean stream comprising the unconverted oil and a solid-rich stream comprising the solid catalyst particles and the solids formed during the hydroconversion reaction,

[0012] hydrotreating the solid-free lean stream comprising the unconverted oil in the presence of hydrogen and a hydrotreating catalyst in a heavy oil hydrotreating unit under heavy oil hydrotreating conditions, thereby producing a hydrotreated effluent, and

[0013] recycling at least a portion of the hydrotreated effluent to the reaction zone of the slurry hydroconversion reactor.

[0014] In accordance with yet another illustrative embodiment, a system comprises:

[0015] a heavy oil hydrotreating unit comprising a heavy oil hydrotreating reactor configured for hydrotreating a solid-free lean stream comprising unconverted oil processed from a heavy oil feedstock in a slurry hydroconversion reactor, in the presence of hydrogen and a hydrotreating catalyst under heavy oil hydrotreating conditions, thereby producing a hydrotreated effluent,

[0016] a recycle line configured for recycling at least a portion of the hydrotreated effluent, and

[0017] a slurry hydroconversion unit comprising one or more slurry hydroconversion reactors configured for hydroconverting a heavy oil feedstock and the portion of the hydrotreated effluent recycled from the heavy oil hydrotreating unit in the presence of hydrogen and a slurry hydroconversion catalyst under slurry hydroconversion conditions, thereby producing a slurry hydroconversion effluent comprising a gas product and a slurry product comprising upgraded heavy oil, unconverted oil, solid catalyst particles and solids formed during a hydroconversion reaction.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In combination with the accompanying drawings and with reference to the following detailed description, the features, advantages, and other aspects of the implementations of the present disclosure will become more apparent, and several implementations of the present disclosure are illustrated herein by way of example but not limitation. The principles illustrated in the example embodiments of the drawings can be applied to alternate processes and apparatus. Additionally, the elements and features shown in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the example embodiments. Certain dimensions or positions may be exaggerated to help visually convey such principles. In the drawings, the same reference numerals used in different embodiments designate like or corresponding, but not necessarily identical, elements. In the accompanying drawings:

[0019] FIG. 1 illustrates a simplified process flow diagram of a system and process for heavy oil upgrading, according to one or more illustrative embodiments.

[0020] FIGS. 2A and 2B illustrate a simplified process flow diagram of a system and process for heavy oil upgrading, according to one or more illustrative embodiments.DETAILED DESCRIPTION

[0021] Various illustrative embodiments described herein are directed to systems and processes for upgrading heavy oil feedstocks into lower boiling, higher quality materials. In particular, the present disclosure relates to processes and systems for integrating a heavy oil hydrotreating unit with a slurry hydroconversion reactor to achieve full or near full conversion of heavy oil.

[0022] Due to its high viscosity, density, and sulfur content, heavy oil is difficult to transport, refine, and upgrade, and thus has a lower market value. As mentioned above, 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.

[0023] Hydrocracking is one of the methods employed to improve the quality and value of heavy oil. In particular, slurry hydroconversion uses a dispersed catalyst which is continuously doped into the heavy oil feedstock. The benefits of slurry hydroconversion over other hydrogen-addition technologies may include higher product yield, feed conversion, operational reliability, flexibility and adaptability. However, when the conversion of a heavy oil feedstock using slurry hydroconversion approaches full conversion, the unconverted oil (UCO residuum) becomes more resistant to cracking and more undesired gas products (e.g., C1 to C4 hydrocarbons) are generated. These gas products reduce the liquid yield and the economic efficiency of the slurry hydroconversion. In addition, such high conversion also leads to high coke production, poor quality in the unconverted oil as well as various operating issues (e.g., equipment fouling).

[0024] In addition, since the slurry reactor used in the slurry hydroconversion has lower catalyst loading, the slurry hydroconversion is not as efficient as a fixed-bed reactor to add hydrogen to the unconverted oil. Due to the high operating temperature in a slurry reactor, thermal cracking prevails over catalytic conversion and hydrogenation. The high gas yield and flash at the high temperatures also leads to lower hydrogen partial pressure, and in turn, lower catalytic performance. With a packed catalyst in the form of solid pellets or granules, a fixed-bed reactor has a higher catalyst loading and a higher hydrogen partial pressure than a slurry reactor, and thus can achieve a higher degree of hydrogen addition / saturation.

[0025] Accordingly, it would be desirable to provide systems and processes that can allow for a full or near full conversion of heavy oils that can mitigate equipment fouling while also minimizing loss of reactor productivity and losses of portions of a feed to lower value products, including reducing or minimizing overcracking, and thus reducing gas (C1 to C4) and coke formation.Definitions

[0026] To define more clearly the terms used herein, the following definitions are provided. Unless otherwise indicated, the following definitions are applicable to this disclosure. If a term is used in this disclosure but is not specifically defined herein, the definition from the IUPAC Compendium of Chemical Terminology can be applied, as long as that definition does not conflict with any other disclosure or definition applied herein or render indefinite or non-enabled any claim to which that definition is applied. To the extent that any definition or usage provided by any document incorporated herein by reference conflicts with the definition or usage provided herein, the definition or usage provided herein controls.

[0027] While systems and processes are described in terms of “comprising” various components or steps, the systems and processes can also “consist essentially of” or “consist of” the various components or steps, unless stated otherwise.

[0028] The terms “a,”“an,” and “the” are intended to include plural alternatives, e.g., at least one. The terms “including,”“with,” and “having,” as used herein, are defined as comprising (i.e., open language), unless specified otherwise.

[0029] Various numerical ranges are disclosed herein. When Applicant discloses or claims a range of any type, Applicant's intent is to disclose or claim individually each possible number that such a range could reasonably encompass, including end points of the range as well as any sub-ranges and combinations of sub-ranges encompassed therein, unless otherwise specified. For example, all numerical end points of ranges disclosed herein are approximate, unless excluded by proviso.

[0030] Values or ranges may be expressed herein as “about,” from “about” one particular value, and / or to “about” another particular value. When such values or ranges are expressed, other embodiments disclosed include the specific value recited, from the one particular value, and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that there are a number of values disclosed therein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. In another aspect, use of the term “about” means ±20% of the stated value, ±15% of the stated value, ±10% of the stated value, ±5% of the stated value, ±3% of the stated value, or ±1% of the stated value.

[0031] Applicant reserves the right to proviso out or exclude any individual members of any such group of values or ranges, including any sub-ranges or combinations of sub-ranges within the group, that can be claimed according to a range or in any similar manner, if for any reason Applicant chooses to claim less than the full measure of the disclosure, for example, to account for a reference that Applicant may be unaware of at the time of the filing of the application. Further, Applicant reserves the right to proviso out or exclude any members of a claimed group.

[0032] The term “continuous” as used herein shall be understood to mean a system that operates without interruption or cessation for a period of time, such as where reactant(s) and catalyst(s) are continually fed into a reaction zone and products are continually or regularly withdrawn without stopping the reaction in the reaction zone.

[0033] A “fresh catalyst” as used herein denotes a catalyst which has not previously been used in a catalytic process.

[0034] A “spent catalyst” as used herein denotes a catalyst that has less activity at the same reaction conditions (e.g., temperature, pressure, inlet flows) than the catalyst had when it was originally exposed to the process. This can be due to a number of reasons, several non-limiting examples of causes of catalyst deactivation are coking or carbonaceous material sorption or accumulation, steam or hydrothermal deactivation, metals (and ash) sorption or accumulation, attrition, morphological changes including changes in pore sizes, cation or anion substitution, and / or chemical or compositional changes.

[0035] A “regenerated catalyst” as used herein denotes a catalyst that had become spent, as defined above, and was then subjected to a process that increased its activity to a level greater than it had as a spent catalyst. This may involve, for example, reversing transformations or removing contaminants outlined above as possible causes of reduced activity. The regenerated catalyst typically has an activity that is equal to or less than the fresh catalyst activity.

[0036] The term “primarily” shall be understood to mean an amount greater than 50%, e.g., 50.01 to 100%, or any range between, e.g., 51 to 95%, 75% to 90%, at least 60%, at least 70%, at least 80%, etc.

[0037] The terms “slurry” means a mixture of liquid and solid.

[0038] The terms “hydrocracking” and “hydroconversion” shall refer to a process whose primary purpose is to reduce the boiling range of a heavy oil feedstock and in which a substantial portion of the feedstock is converted into products with boiling ranges lower than that of the original feedstock. Hydrocracking or hydroconversion generally involves fragmentation of larger hydrocarbon molecules into smaller molecular fragments having a fewer 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 radical ends or moieties with hydrogen. The hydrogen atoms or radicals that react with hydrocarbon free radicals during hydrocracking can be generated at or by active catalyst sites.

[0039] The term “hydrotreating” shall refer to operations whose primary purpose is to remove impurities such as sulfur, nitrogen, oxygen, halides, and trace metals from the feedstock and saturate olefins and / or stabilize hydrocarbon free radicals by reacting them with hydrogen rather than allowing them to react with themselves. The primary purpose is not to change the boiling range of the feedstock. Hydrotreating is most often carried out using a fixed bed reactor, although other hydroconversion reactors can also be used for hydrotreating, an example of which is an ebullated bed hydrotreater.

[0040] The terms “upgrade,”“upgrading” and “upgraded,” when used to describe a feedstock that is being or has been subjected to hydroconversion, or a resulting material or product, refer to one or more of a reduction in molecular weight of the feedstock, a reduction in boiling point range of the feedstock, a reduction in concentration of asphaltenes, a reduction in concentration of hydrocarbon free radicals, and / or a reduction in quantity of impurities, such as sulfur, nitrogen, oxygen, halides, and metals.

[0041] The term “zone” can refer to an area including one or more equipment items and / or one or more sub-zones. Equipment items can include one or more reactors or reactor vessels, separation vessels, distillation towers, heaters, exchangers, pipes, pumps, compressors, and controllers. Additionally, an equipment item, such as a reactor, dryer, or vessel, can further include one or more zones or sub-zones.

[0042] The term “effluent” refers to a stream that is passed out of a reactor, a reaction zone, or a separator following a particular reaction or separation. Generally, an effluent has a different composition than the stream that entered the reactor, reaction zone, or separator. It should be understood that when an effluent is passed to another component or system, only a portion of that effluent may be passed. For example, a slipstream may carry some of the effluent away, meaning that only a portion of the effluent may enter the downstream component or system.

[0043] The terms “wt. %,”“vol. %,” or “mol. %” refers to a weight percentage of a component, a volume percentage of a component, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, that includes the component. In a non-limiting example, 10 grams of component in 100 grams of the material is 10 wt. % of component.

[0044] The non-limiting illustrative embodiments described herein overcome the drawbacks discussed above by providing systems and processes that allow for the hydroconversion of heavy oil feedstocks that can mitigate equipment fouling while also minimizing loss of reactor productivity and losses of portions of a heavy oil feedstock to lower value products, including reducing or minimizing overcracking. The disclosure is based on the discovery that hydrogen addition / saturation allows for unconverted oil to be easier to crack. Hydrogen addition / saturation is a process that adds hydrogen to the heavy oil feedstock or the intermediate product to increase the hydrogen-to-carbon ratio while reducing the aromaticity and heteroatom content of the unconverted oil. Hydrogen addition / saturation can enhance the cracking performance and the product quality of the hydroconversion process.

[0045] Accordingly, the non-limiting illustrative embodiments of the present disclosure overcome the foregoing drawings by providing systems and processes that can achieve full or near full conversion of heavy oil (e.g., about 97% or higher by 550° C.+ true boiling point) by integrating a heavy oil hydrotreating unit with a slurry hydroconversion reactor. By utilizing hydrogen, and therefore enabling product hydrogenation, in the heavy oil hydrotreating unit, the unconverted oil processed from a heavy oil feedstock in the slurry hydroconversion reactor becomes more hydrogenated and easier to crack and convert, which leads to lower gas-make (i.e., C1 to C4 hydrocarbons), higher conversion in the slurry reactor after it is recycled back and coke formation. In addition, it also improves the operability and reliability of the slurry hydroconversion reactor due to improved oil quality. Further, the systems and processes of the present disclosure also increase the flexibility and the adaptability of the slurry hydroconversion process to different types of heavy oils and different market demands thereby enhancing the value and the utilization of heavy oil resources and benefiting the oil industry and the environment.General Process

[0046] The non-limiting illustrative embodiments described herein are directed to a continuous process for upgrading a heavy oil feedstock. In non-limiting illustrative embodiments, the process can involve receiving, in a heavy oil hydrotreating unit, a solid-free lean stream comprising unconverted oil processed from a heavy oil feedstock in a slurry hydroconversion reactor, hydrotreating the solid-free lean stream comprising the unconverted oil in the presence of hydrogen and a hydrotreating catalyst under heavy oil hydrotreating conditions, thereby producing a hydrotreated effluent, and recycling at least a portion of the hydrotreated effluent to a reaction zone of the slurry hydroconversion reactor.

[0047] In non-limiting illustrative embodiments, the process can involve exposing a heavy oil feedstock to a slurry hydroconversion catalyst under slurry hydroconversion conditions in a reaction zone of a slurry hydroconversion reactor, thereby producing a slurry hydroconversion effluent comprising a gas product and a slurry product comprising upgraded heavy oil, unconverted oil, solid catalyst particles and solids formed during a hydroconversion reaction, separating the gas product and upgraded heavy oil from the slurry product using one or more separators to produce a slurry stream comprising the unconverted oil, the solid catalyst particles and the solids formed during the hydroconversion reaction, separating the slurry stream using one or more solid-liquid separators to produce a solid-free lean stream comprising the unconverted oil and a solid-rich stream comprising the solid catalyst particles and the solids formed during the hydroconversion reaction, hydrotreating the solid-free lean stream comprising the unconverted oil in the presence of hydrogen and a hydrotreating catalyst under heavy oil hydrotreating conditions to produce a hydrotreated effluent, and recycling at least a portion of the hydrotreated effluent to the reaction zone of the slurry hydroconversion reactor.

[0048] The non-limiting illustrative embodiments of the present disclosure will be specifically described below with reference to the accompanying drawing. For the purpose of clarity, some steps leading up to the processing of a heavy oil feedstock as illustrated in FIG. 1 may be omitted. In other words, one or more well-known processing steps which are not illustrated but are well-known to those of ordinary skill in the art have not been included in the figure. This is not intended to be interpreted as a limitation of any particular embodiment, or illustration, or scope of the claims.

[0049] FIG. 1 illustrates a continuous process as described herein that can be implemented using a system including at least a slurry hydroconversion unit, a separation unit, a solid-liquid separation unit, and a heavy oil hydrotreating unit. As will be appreciated by one of skill in the art, components of the system can be in fluid communication with each other through any suitable conduits (e.g., pipes, streams, etc.). For ease of understanding, specific examples mentioned in the following description are all illustrative and are not used to limit the protection scope of the present disclosure.Slurry Hydroconversion Unit

[0050] A system 100 first includes a slurry hydroconversion unit 102 for receiving a feed 101 including at least a heavy oil feedstock, a slurry hydroconversion catalyst, a hydrogen-containing stream, and a hydrotreated effluent 124 comprising an upgraded heavy oil recycled from a heavy oil hydrotreating unit 120 as discussed below. Although only one injection point in slurry hydroconversion unit 102 is shown for introducing the heavy oil feedstock, the slurry hydroconversion catalyst and the hydrogen-containing stream, it is to be understood that slurry hydroconversion unit 102 can be designed to have multiple injection points. For example, slurry hydroconversion unit 102 can have an injection point for each the heavy oil feedstock, the slurry hydroconversion catalyst and the hydrogen-containing stream. Other examples include slurry hydroconversion unit 102 having an injection point for a mixture of the heavy oil feedstock and the slurry hydroconversion catalyst and an injection point for the hydrogen-containing stream.

[0051] In various embodiments, the heavy oil feedstock can be processed to form a partially upgraded heavy oil product e.g., at least about 90% of the heavy oil feedstock can be upgraded, or at least about 95% of the heavy oil feedstock can be upgraded, or at least about 97% of the heavy oil feedstock can be upgraded and up to about 99% of the heavy oil feedstock can be upgraded. The heavy oil feedstock may be any suitable heavy hydrocarbon. Examples of heavy oils include, but are not limited to, heavy crude oils, oils (such as bitumen) from oil sands, and heavy oils derived from coal, and blends of such feeds. In some aspects, the heavy oil feedstock can also include at least a portion corresponding to a heavy refinery fraction, such as distillation residues, heavy oils coming from catalytic treatment (e.g., heavy cycle slurry oils or main column bottoms from fluid catalytic cracking), and / or thermal tars (e.g., oils from visbreaking, steam cracking, or similar thermal or non-catalytic processes).

[0052] In some embodiments, the heavy oil feedstock can be liquid or semi-solid at ambient temperature. Such heavy oil feedstocks can include a substantial portion of the heavy oil feedstock that boils at 650° F. (343° C.) or higher. For example, the portion of the heavy oil feedstock that boils at less than 650° F. (343° C.) can correspond to about 5 wt. % to about 40 wt. % of the heavy oil feedstock, or about 10 wt. % to about 30 wt. % of the heavy oil feedstock, or about 5 wt. % to about 20 wt. % of the heavy oil feedstock. Additionally or alternately, a substantial portion of the heavy oil feedstock can also correspond to compounds with a boiling point of 566° C. or higher. In some embodiments, about 50 wt. % or more of the heavy oil feedstock can have a boiling point of 566° C. or more, or about 60 wt. % of the heavy oil feedstock or more, or about 70 wt. % of the heavy oil feedstock or more, or about 80 wt. % of the heavy oil feedstock or more, such as up to substantially all of the heavy oil feedstock corresponding to components with a boiling point of 566° C. or more, e.g., about 99.5 wt. %. In some embodiments, about 50 wt. % or more of the heavy oil feedstock can have a boiling point of 593° C. or more, or about 60 wt. % of the heavy oil feedstock or more, or about 70 wt. % of the heavy oil feedstock or more, or about 80 wt. % of the heavy oil feedstock or more, such as up to substantially all of the heavy oil feedstock corresponding to components with a boiling point of 593° C. or more, e.g., about 99.5 wt. %. In this disclosure, boiling points can be determined by a convenient method, such as ASTM D2887, ASTM D7169, or another suitable standard method.

[0053] Density, or weight per volume, of the heavy oil feedstock can be determined according to ASTM D287 and is provided in terms of API gravity. In general, the higher the API gravity, the less dense the oil. In some embodiments, API gravity of the heavy oil feedstock can be about 160 or less, about 120 or less, or about 8° or less.

[0054] In some embodiments, the heavy oil feedstock can be high in metals. For example, the heavy oil feedstock can be high in total nickel (Ni), vanadium (V) and iron (Fe) contents. In one embodiment, the heavy oil feedstock can contain at least 0.00005 grams of Ni / V / Fe (50 ppm) or at least 0.0002 grams of Ni / V / Fe (200 ppm) per gram of heavy oil, on a total elemental basis of nickel, vanadium, and iron. In other embodiments, the heavy oil feedstock can contain at least 500 wppm of nickel, vanadium, and iron, such as at least 1000 wppm.

[0055] In addition, heteroatoms such as nitrogen and sulfur are typically found in the heavy oil feedstock, often in organically-bound form. In some embodiments, the nitrogen content can range from about 0.1 wt. % to about 3.0 wt. % elemental nitrogen, or about 1.0 wt. % to about 3.0 wt. %, or about 0.1 wt. % to about 1.0 wt. % elemental nitrogen, based on total weight of the heavy oil feedstock. In some embodiments, the nitrogen containing compounds can be present as basic or non-basic nitrogen species. Examples of basic nitrogen species include quinolines and substituted quinolines. Examples of non-basic nitrogen species include carbazoles and substituted carbazoles.

[0056] In some embodiments, the sulfur content of the heavy oil feedstock can range from about 0.1 wt. % to about 10 wt. % elemental sulfur, or about 1.0 wt. % to about 10 wt. %, or about 0.1 wt. % to about 5.0 wt. %, or about 1.0 wt. % to about 7.0 wt. % elemental sulfur, based on total weight of the heavy oil feedstock. In some embodiments, the sulfur will usually be present as organically-bound sulfur. Examples of such sulfur compounds include the class of heterocyclic sulfur compounds such as, for example, thiophenes, tetrahydrothiophenes, benzothiophenes and their higher homologs and analogs. Other examples of organically-bound sulfur compounds include aliphatic, naphthenic, and aromatic mercaptans, sulfides, and di- and polysulfides. In some aspects involving slurry hydroconversion as the hydroconversion stage, higher sulfur feeds can be preferred, as carbon-sulfur bonds can tend to be the first to break under slurry hydroconversion conditions.

[0057] In some embodiments, the heavy oil feedstock can be high in n-heptane asphaltenes. In some aspects, the heavy oil feedstock can contain about 5 wt. % to about 80 wt. % of n-heptane asphaltenes, or about 5 wt. % to about 60 wt. %, or about 5 wt. % to about 50 wt. %, or about 20 wt. % to about 80 wt. %, or about 10 wt. % to about 50 wt. %, or about 20 wt. % to about 60 wt. % of n-heptane asphaltenes.

[0058] Still another method for characterizing a heavy oil feedstock is based on the Conradson carbon residue (CCR) of the feedstock, or alternatively the micro carbon residue (MCR) content. The Conradson carbon residue / micro carbon residue content of the heavy oil feedstock can be about 5.0 wt. % to about 50 wt. %, or about 5.0 wt. % to about 30 wt. %, or about 10 wt. % to about 40 wt. %, or about 20 wt. % to about 50 wt. %.

[0059] In some embodiments, the slurry hydroconversion catalyst can correspond to one or more catalytically active metals in particulate form and / or supported on particles. In some embodiments, the slurry hydroconversion catalyst can correspond to particulates that are retained within the heavy oil feedstock after using a froth treatment to form the feed. In still other aspects, a mixture of catalytically active metals and particulates retained in the heavy hydrocarbon feed can be used.

[0060] Suitable catalyst concentrations can range from about 50 weight parts per million (wppm) to about 20,000 wppm (or about 2 wt. %), depending on the nature of the catalyst. In some embodiments, the catalyst can be incorporated into a heavy oil feedstock directly, or the catalyst can be incorporated into a side or slip stream of the heavy oil feedstock and then combined with the main flow of the heavy oil feedstock. Still another option is to form catalyst in-situ by introducing a catalyst precursor, such as Mo octoate into a heavy oil feedstock (or a side / slip stream of heavy oil feedstock) and forming catalyst by a subsequent reaction.

[0061] Catalytically active metals for use in slurry hydroconversion can include those from Groups 4-10 of the IUPAC Periodic Table of Elements. Examples of suitable metals include molybdenum (Mo), tungsten (W), iron (Fe), nickel (Ni), cobalt (Co), ruthenium (Ru), and mixtures thereof. The catalytically active metal may be present as a solid particulate in elemental form or as an organic compound or an inorganic compound such as a sulfide or other ionic compound. Metal or metal compound nanoaggregates may also be used to form the solid particulates.

[0062] A slurry hydroconversion catalyst in the form of a solid particulate is generally a compound of a catalytically active metal, or a metal in elemental form, either alone or supported on a refractory material such as an inorganic metal oxide (e.g., alumina, silica, titania, zirconia, and mixtures thereof). Other suitable refractory materials can include carbon, coal, and clays. Zeolites and non-zeolitic molecular sieves are also useful as solid supports. One advantage of using a support is its ability to act as a “coke getter” or adsorbent of asphaltene precursors that might otherwise lead to fouling of process equipment.

[0063] The slurry hydroconversion catalyst can be in the form of particles having an average particle size of less than about 300 microns. “Average particle size” is synonymous with D50, meaning half of the population of particles has a particle size above this point, and half below. The particle size refers to primary particles. The particle size may be measured by laser light scattering techniques, with dispersions or dry powders, for example according to ASTM D4464.

[0064] In some aspects, it can be desirable to form the slurry hydroconversion catalyst for slurry hydroconversion in situ, such as forming the slurry hydroconversion catalyst from a metal sulfate catalyst precursor or another type of catalyst precursor that decomposes or reacts in the hydroconversion reaction zone environment, or in a pretreatment step, to form a desired, well-dispersed and catalytically active solid particulate. Precursors also include oil-soluble organometallic compounds containing the catalytically active metal of interest that thermally decompose to form the solid particulate having catalytic activity. Other suitable precursors include metal oxides that may be converted to catalytically active (or more catalytically active) compounds such as metal sulfides.

[0065] The hydrogen-containing stream includes hydrogen, which is contained in a hydrogen “treat gas,” for injecting into slurry hydroconversion unit 102. The treat gas can be either pure hydrogen or a hydrogen-containing gas, which is a gas stream containing hydrogen in an amount that is sufficient for the intended reaction(s), optionally including one or more other gases (e.g., nitrogen and light hydrocarbons such as methane). The treat gas stream introduced into a reaction stage in slurry hydroconversion unit 102 can be about 90 vol. % or less, or about 80 vol. % or less, or about 60 vol. % or less, such as down to about 40 vol. % or possibly still lower. In other aspects, the H2 content of the hydrogen-containing stream can be about 80 vol. % or more, or about 90 vol. % or more. For example, the hydrogen-containing stream can contain about 80 vol. % to 100 vol. % H2, or about 90 vol. % to 100 vol. % H2, or about 80 vol. % to about 98 vol. % H2, or about 90 vol. % to about 98 vol. % H2, or about 80 vol. % to about 96 vol. % H2, or about 90 vol. % to about 96 vol. % H2.

[0066] Optionally, the hydrogen-containing stream can be substantially free (less than about 1 vol. %) of impurities such as H2S and NH3 and / or such impurities can be substantially removed from a treat gas prior to use. Additionally or alternately, the combined content of H2S, CO, and NH3 in the hydrogen-containing stream can be about 1.0 vol. % or more, or about 3.0 vol. % or more, or about 5.0 vol. % or more, such as up to about 15 vol. % or possibly still higher. Further additionally or alternately, the combined content of H2, H2O, and N2 in the hydrogen-containing stream introduced into slurry hydroconversion unit 102 can be about 95 vol. % or less, or about 90 vol. % or less, or about 85 vol. % or less, such as down to about 75 vol. % or possibly still lower. For example, the combined content of H2, H2O, and N2 in the hydrogen-containing stream introduced into slurry hydroconversion unit 102 can be about 75 vol. % to about 95 vol. %.

[0067] Turning back to FIG. 1, slurry processing is an example of a type of slurry hydroconversion that can be performed under limited severity conditions and that can also allow for withdrawal and addition of the slurry hydroconversion catalyst during operation of the hydroconversion process. In system 100, slurry hydroconversion can be performed by processing feed 101 in one or more slurry hydroconversion reactors of slurry hydroconversion unit 102. The slurry hydroconversion process can be carried out in a variety of slurry hydroconversion reactors of slurry hydroconversion unit 102. Suitable slurry hydroconversion reactors include, for example, continuous stirred tank reactors, fluidized bed reactors, spouted bed reactors, spray reactors, bubble column reactors, liquid circulation reactors, slurry circulation reactors, and combinations thereof. Slurry hydroconversion unit 102 may be single-stage or multi-stage and may be comprised of a single slurry hydroconversion reactor or multiple slurry hydroconversion reactors. In some embodiments, one or more slurry hydroconversion reactors may be utilized in parallel, in series or a combination thereof.

[0068] In general, the reaction conditions in slurry hydroconversion unit 102 can vary based on the nature of the catalyst, the nature of the feed, the desired products, and / or the desired amount of conversion. The reaction conditions for slurry hydroconversion can be selected so that the net conversion of feed across all slurry reactors (e.g., if there is more than one arranged in series) of slurry hydroconversion unit 102 is at least about 80%, such as at least about 90%, or at least about 95%. For slurry hydroconversion, conversion is defined as conversion of compounds with boiling points greater than a conversion temperature, such as 975° F. (524° C.), to compounds with boiling points below the conversion temperature. Alternatively, the conversion temperature for defining the amount of conversion can be 1022° F. (550° C.). The portion of a heavy oil feedstock that is unconverted after slurry hydroconversion can be referred to as an unconverted oil (UCO) fraction processed from the heavy oil feedstock in slurry hydroconversion unit 102.

[0069] The reaction conditions within slurry hydroconversion unit 102 that correspond to a selected conversion amount can include a temperature of about 400° C. to about 480° C., or about 425° C. to about 480° C., or about 450° C. to about 480° C., or about 410° C. to about 450° C. Some types of slurry hydroconversion reactors are operated under high hydrogen partial pressure conditions, such as having a hydrogen partial pressure of about 1000 psig to about 3400 psig (about 6.9 MPag to about 23.4 MPag), for example at least about 1200 psig (about 8.3 MPag), or at least about 1500 psig (about 10.3 MPag). Examples of hydrogen partial pressures can be about 1000 psig to about 3000 psig (about 6.9 MPag to about 20.7 MPag), or about 1000 psig to about 2500 psig (about 6.9 to about 17.2 MPag), or about 1500 psig to about 3400 psig (about 10.3 MPag to about 23.4 MPag), or about 1000 psig to about 2000 psig (about 6.9 MPag to about 13.8 MPag), or about 1200 to about 2500 psig (about 8.3 MPag to about 17.2 MPag). Since the catalyst is in slurry form within the feed, the space velocity for a slurry hydroconversion reactor can be characterized based on the volume of feed processed relative to the volume of the reactor used for processing the feed. Suitable space velocities for slurry hydroconversion can range, for example, from about 0.05 h−1 to about 5 h−1, such as about 0.1 h−1 to about 2 h−1.

[0070] The slurry hydroconversion reaction in slurry hydroconversion unit 102 produces a slurry hydroconversion effluent 104 including at least a gaseous product and a slurry product. In some embodiments, the gaseous product stream can include light hydrocarbon gases produced in slurry hydroconversion unit 102 as well as excess hydrogen or other by-product gases. The light hydrocarbon gases can include, for example, C1 to C4 gases such as methane, ethane, propane, ethylene, propylene, mixed butenes, or combinations of these. The gaseous product stream can include the excess hydrogen from slurry hydroconversion unit 102. Additionally, the gaseous product stream can further include any by-product gases produced as a by-product of hydroconversion in slurry hydroconversion unit 102. By-product gases can include, for example, sulfur-containing gases such as hydrogen sulfide, nitrogen-containing gases such as ammonia, or combinations of these.

[0071] In some embodiments, the slurry product includes upgraded heavy oil, unconverted oil, a vapor fraction, solid catalyst particles and solids formed during a hydroconversion reaction. In some embodiments, upgraded heavy oil includes for example, distillates such as, for example, atmospheric gas oil, light vacuum gas oil, and heavy vacuum gas oil. In some embodiments, unconverted oil and solid catalyst particles form a slurry phase in the slurry product.Separation Unit

[0072] System 100 further includes a separation unit 106 for receiving slurry hydroconversion effluent 104 following exposing feed 101 to slurry hydroconversion conditions in slurry hydroconversion unit 102. The terms “separation unit” and “separator” refer to any separation device(s) that at least partially separates one or more chemical constituents in a mixture from one another. Separation unit 106 includes one or more separation units for separating the various components in slurry hydroconversion effluent 104 including at least the gaseous product stream and the slurry product. For example, a separation unit may selectively separate different chemical constituents from one another, forming one or more chemical fractions. Suitable separation units include, for example, gas / liquid separators, including hot high- and low-pressure separators, intermediate high- and low-pressure separators, cold high- and low-pressure separators, strippers, integrated strippers and combinations thereof, distillation columns, fractionators, evaporators, flash drums, knock-out drums, knock-out pots, centrifuges, filtration devices, traps, scrubbers, expansion devices, membranes, or combinations of any of these.

[0073] The method of separating in separation unit 106 can advantageously be implemented by any method known to the person skilled in the art such as, for example, the combination of one or a plurality of high- and / or low-pressure separators and / or distillation steps and / or high- and / or low-pressure stripping, and / or liquid / liquid extraction steps and / or solid / liquid separation steps and / or centrifuging steps.

[0074] It will be understood by those skilled in the art that high-pressure separators operate at a pressure that is close to slurry hydroconversion unit 102 pressure, e.g., 0 to about 10 bar below the reactor outlet pressure, while a low-pressure separator is operated at a pressure that is lower than slurry hydroconversion unit 102 pressure or high-pressure separator, e.g., 0 to about 50 bar. Similarly, it will be understood by those skilled in the art that hot means that the hot-separator is operated at a temperature that is close to or slightly lower than slurry hydroconversion unit 102 temperature, while intermediate- and cold-separators are at a reduced temperature relative to slurry hydroconversion unit 102. For example, a cold-separator can be at a temperature that can be achieved via an air cooler. An intermediate temperature will be understood to mean any temperature between the temperature of a hot- and cold-separator.

[0075] In some embodiments, separation unit 106 can include a plurality of separators including, for example, a hot separator, such as a hot high-pressure separator, a hot low-pressure separator, and / or an integrated stripper separator, and a cold separator, such as a cold high-pressure separator and / or a cold low-pressure separator. For example, a hot high-pressure separator can flash off a hydrogen-rich gas effluent 110. The hot high-pressure separator offgas is then cooled, for example, in an air cooler or a heat exchanger, and directed to a cold separator, where at least a portion of the light hydrocarbon gases are separated from the offgas stream as a light hydrocarbon effluent 109. In some embodiments, the gaseous product can be cooled using, for example, an air cooler or a heat exchanger, and then the light hydrocarbon gases are separated from the hydrogen using, for example, a cold separator such as a cold high-pressure separator to generate light hydrocarbon effluent 109 and hydrogen-rich gas effluent 110. The cold high-pressure separator may be any unit that is operable to separate the light hydrocarbon gases from the hydrogen.

[0076] Light hydrocarbon effluent 109 exits separation unit 106 and can be sent to a light hydrocarbon fractionation unit (not shown) for further processing. Hydrogen-rich gas effluent 110 exits separation unit 106 and can be recycled back to slurry hydroconversion unit 102. In some embodiments, hydrogen-rich gas effluent 110 can be subjected to a small purge to remove impurities before being recycled to slurry hydroconversion unit 102 for use in the slurry hydroconversion process.

[0077] In some embodiments, the separated slurry product is sent to a hot separator in separation unit 106 such as a hot high-pressure separator, where vapors are stripped off to generate a purified slurry product. Next, the purified slurry product is further separated into a liquid upgraded heavy oil effluent 108 comprised of, for example, distillates such as atmospheric gas oil, light vacuum gas oil, and heavy vacuum gas oil, and a slurry stream effluent 112 comprised of the unconverted oil, the solid catalyst particles and the solids formed during the hydroconversion reaction. In some embodiments, liquid upgraded heavy oil effluent 108 is separated from the purified slurry product using a pre-flash column. In some embodiments, the purified slurry product is introduced into a vacuum tower for fractionating the liquid upgraded heavy oil from the slurry stream to generate liquid upgraded heavy oil effluent 108 and slurry stream effluent 112. In some embodiments, the vacuum tower can be operated, for example, at a temperature ranging from about 250° C. to about 400° C. and a pressure ranging from about 0.01 torr to about 700 torr. Liquid upgraded heavy oil effluent 108 can be sent to a fractionator, where it can be separated into different products, such as, for example, naphtha, kerosene, diesel, and vacuum gas oil.Solid-Liquid Separation Unit

[0078] Slurry stream effluent 112 exits separation unit 106 and is sent to a solid-liquid separation unit 114. In some embodiments, slurry stream effluent 112 can be extracted from a hot low-pressure separator (HLPS), slurry stripper or slurry vacuum distillation unit before sending to solid-liquid separation unit 114.

[0079] Slurry stream effluent 112 (comprising unconverted oil, solid catalyst particles and solids formed during the hydroconversion process) is passed directly from separation unit 106 to solid-liquid separation unit 114 wherein solids in slurry stream effluent 112 are separated therefrom to produce a solid-rich stream 116 comprising the solid catalyst particles and the solids formed during the hydroconversion reaction and a solid-free lean stream 118 comprising the unconverted oil. A “solid-rich stream” is intended herein to identify a liquid, slurry, or solid stream that contains most if not all the amounts of solids (e.g., 99%) contained in slurry stream effluent 112 entering solid-liquid separation unit 114. A “solid-free lean stream” is intended herein to identify a liquid or liquid stream containing negligible amounts of solids, generally lower than about 1000 ppm, or lower than about 100 ppm, e.g., from about 10 ppm to about 1000 ppm solids.

[0080] In some embodiments, the solids can be separated from slurry stream effluent 112 using conventional techniques such as, for example, centrifugation, sedimentation or gravity settling, filtering, or any other suitable separator or combination of separators.

[0081] In some embodiments, solid-liquid separation unit 114 carries out a solid-liquid separation process such as a filtration process or step. Suitable filtration processes generally include, for example, using a mesh, screen, cross flow filtration, backwash filtration, or a combination thereof. In some embodiments, filtration processes include membrane filtration processes (e.g., microfiltration processes, using membranes having an average pore size of less than about 10 microns, more particularly, an average pore size of less than about 5 microns, or an average pore size of less than about 2 microns). In some embodiments, the filtration membrane may be composed of a material such as, for example, metals, polymeric materials, ceramics, glasses, nanomaterials, or a combination thereof. Suitable metals include, for example, stainless steel, titanium, bronze, aluminum, nickel, copper and alloys thereof. Such membranes may also be coated for various reasons, and with various materials, including inorganic metal oxides coatings.

[0082] In a non-limiting embodiment, a filtration process for use herein is cross flow filtration. “Cross flow filtration” (or crossflow filtration or tangential flow filtration (TFF)) refers to a filtration technique in which the feed stream flows parallel or tangentially along the surface of a membrane and the filtrate flows across the membrane. In cross flow filtration, typically only the material which is smaller than the membrane pore size passes through (across) the membrane as permeate or filtrate, and everything else is retained on the feed side of the membrane as retentate or concentrate. Suitable cross flow filtration systems are well known and described in various patents such as, for example, U.S. Pat. No. 8,080,155, the contents of which are incorporated by reference herein.

[0083] For example, utilizing membrane cross flow filtration, solid-rich stream 116 comprising the solid catalyst particles and the solids formed during the hydroconversion reaction are separated from solid-free lean stream 118 comprising the unconverted oil, i.e., “deoiled,” in solvent as a separate stream. A second stream is produced comprising the heavy oil and solvent. Solvent can be subsequently separated from solid-rich stream 116 using processes including evaporation to dryness. Solvent can also be recovered from solid-free lean stream 118 for subsequent reuse, with the recovered heavy oil being a product.

[0084] In one embodiment, a membrane filtration assembly, e.g., microfiltration, is employed in a deoiling zone to separate the unconverted oil from the solid catalyst particles and the solids formed during the hydroconversion reaction. The membranes employed can be of the “tortuous-pore” or “capillary-pore” type, or a combination of multiple membrane layers, some tortuous-pore membranes some capillary-pore membranes. As used herein, tortuous-pore refers to membranes having a structure resembles a sponge with a network of interconnecting tortuous pores. Capillary-pore refers to membranes having approximately straight-through cylindrical capillaries.

[0085] Any suitable filtration medium (membrane) can be utilized in the filtration assembly. In one embodiment, the filtration medium is a porous material which permits heavy oil below a certain size to flow through as the filtrate (or permeate) while retaining the spent catalyst particles and solids in the retentate. In some embodiments, the filtration medium is of sufficient pore size for removing at least 50% of solid-free lean stream 118 from solid-rich stream 116, i.e., for at least 50% of solid-free lean stream 118 to pass through the filter membrane. In some embodiments, the filtration medium is of sufficient pore size for removing at least 60% of solid-free lean stream 118 to pass through the filter membrane. In some embodiments, the filtration medium is of sufficient pore size for removing at least 70% of solid-free lean stream 118 to pass through the filter membrane. In some embodiments, the filtration medium is of sufficient pore size for removing at least 75% of solid-free lean stream 118 to pass through the filter membrane.

[0086] In one embodiment, the filtration medium is a filtration membrane having an effective pore rating (“average pore size”) of about 5 microns or less; for example, from about 0.1 to about 0.3 m, or from about 0.05 to about 0.15 m.

[0087] In some embodiments, suitable material for the construction of the filtration membrane includes polymers, organic materials, inorganic ceramic materials, and metals, as long as they are solvent stable. The term “solvent-stable” refers to a material that does not undergo significant chemical changes to substantially impair the desired properties of the material. Stability can be verified by various well-known techniques, which include, but are not limited to, soaking test, scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).

[0088] In some embodiments, the filtration membrane can be made of polytetrafluoroethylene (Teflon®), for example, polytetrafluoroethylene on woven fiberglass, which can withstand temperatures of 130° C. (266° F.). With the use of polytetrafluoroethylene, the membrane is chemically inert and can handle continuous pH levels of 0 to about 14.

[0089] In some embodiments, the filtration membrane comprises a polymeric material including, for example, poly(acrylic acids), poly(acrylates), polyacetylenes, poly(vinyl acetates), polyacrylonitriles, polyamines, polyamides, polysulfonamides, polyethers, polyurethanes, polyimides, polyvinyl alcohols, polyesters, cellulose, cellulose esters, cellulose ethers, chitosan, chitin, elastomeric polymers, halogenated polymers, fluoroelastomers, polyvinyl halides, polyphosphazenes, polybenzimidazoles, poly(trimethylsilylpropyne), polysiloxanes, poly(dimethyl siloxanes), and copolymers blends thereof. These polymers can be physically or chemically cross-linked to further improve their solvent stability.

[0090] In some embodiments, the filtration membrane comprises an inorganic material such as ceramics (silicon carbide, zirconium oxide, titanium oxide, etc.) having the ability to withstand high temperatures and harsh environments. In one embodiment, the filtration membrane can be constructed from a woven fabric coated with a nanomaterial, e.g., an inorganic metal oxide, allowing the filtration membrane to be in the form of a flexible ceramic membrane foil with advantages of both ceramic and polymeric membranes. In some embodiments, the filtration membrane can be constructed from a metal such as stainless steel, titanium, bronze, aluminum or nickel-copper alloy. In some embodiments, the filtration membrane can be constructed from materials such as sintered stainless steel with an inorganic metal oxide coating, e.g., a titanium oxide coating.

[0091] In some embodiments, the deoiling zone comprises a filtration membrane that is rapidly displaced in a horizontal direction. A retentate of the filtration membrane comprises solid-rich stream 116 and a permeate of the filtration membrane comprises solid-free lean stream 118. In particular, rapidly displacing the filtration membrane in a horizontal direction can comprise rotating the filtration membrane.

[0092] In some embodiments, filtration membrane operating pressure can be in the range of about 30 psi to about 300 psi (about 2 to about 7 bar). Filtering can be conducted at a temperature of about 250° C. to about 350° C. and a pressure of about 80 psi to about 200 psi. In some embodiments, the deoiling zone comprising multiple filtration units is operated at a pressure in the range of about 20 psi to about 400 psi, for example, about 30 to about 300 psi or about 50 psi to about 200 psi. Pressure drops across the filtration membrane in the filtration units, referred to as the transmembrane pressure, are in the range of about 0 psi to about 200 psi, for example, about 0 psi to about 50 psi or about 0 psi to about 25 psi. In one embodiment, the temperature of the deoiling zone can be in the range of about 100° F. to about 700° F., for example, about 150° F. to about 680° F. or about 200° F. to about 400° F.

[0093] In one embodiment, the filtration assembly comprises between one to ten filtration units. In another embodiment, the filtration assembly comprises between four to eight filtration units.

[0094] Solid-rich stream 116 comprising the solid catalyst particles and the solids formed during the hydroconversion reaction can exit solid-liquid separation unit 114 to be one or more of disposed, reclaimed for metal, and / or recycled back to slurry hydroconversion unit 102. In some embodiments, solid-rich stream 116 may be subjected to fractionation prior to recycling back to slurry hydroconversion unit 102. In some embodiments, a small portion of solid-rich stream 116 may be removed as a bleed slurry (not shown). The bleed slurry can be further processed to produce a solid catalyst and a solid-free oil stream. In some embodiments, the solid-free oil stream may be sent to a heavy oil hydrotreater (HOHDT) for upgrading.

[0095] Solid-free lean stream 118 comprising the unconverted oil is passed to heavy oil hydrotreating unit 120 for further upgrading.Heavy Oil Hydrotreating (HOHDT) Unit

[0096] System 100 further includes heavy oil hydrotreating unit 120 for integration with slurry hydroconversion unit 102 to achieve full or near full conversion of the heavy oil feedstock. Heavy oil hydrotreating is used to hydrotreat solid-free lean stream 118 comprising the unconverted oil from solid-liquid separation unit 114. Heavy oil hydrotreating unit 120 includes a heavy oil hydrotreating reactor. The heavy oil hydrotreating reactor is a type of fixed bed reactor that uses a hydrotreating catalyst particularly designed for heavy oil to remove sulfur, nitrogen, metals and other impurities from heavy oil and to saturate unsaturated hydrocarbons. In addition, heavy oil hydrotreating (HOHDT) reactor can also partially crack heavy oil into lighter fractions, although to a significantly less extent than a slurry hydroconversion process.

[0097] Suitable operating conditions generally include ranges known in the art, for example, as may be known for residuum desulfurization system (RDS) reactor processing with notable exceptions. For heavy oil hydrotreating (HOHDT) according to the present disclosure, reactor space velocities are generally lower, for example, in the range of about 0.05 h−1 to about 0.25 h−1, whereas space velocities for RDS systems are typically in the range of about 0.15 h−1 to about 0.40 h−1. Target catalyst lifetimes are also significantly increased for heavy oil hydrotreating operation, typically being in the range of about 2 years to about 3 years compared with about 6 months to about 14 months for RDS systems. Other heavy oil hydrotreating conditions include, for example, a reactor pressure of about 1500 psig to about 3000 psig (about 10.3 MPa to about 20.7 MPa) or from about 2000 psig to about 2500 psig (about 10.3 to about 17.2 MPa); an average reactor temperature of about 680° F. to about 770° F. (about 360° C. to about 410° C.); a hydrogen-to-oil ratio of about 3000 SCFB to about 6000 SCFB; and a hydrogen consumption of about 300 SCFB to about 1200 SCFB.

[0098] In some embodiments, heavy oil hydrotreating unit 120 may comprise an upflow fixed-bed reactor, a downflow fixed-bed reactor, or a combination thereof. Any of these reactors may be a multi-catalyst bed reactor, or multiple single catalyst bed reactors, or a combination thereof.

[0099] Certain feed and product specifications are also applicable to the HOHDT process. For example, solid-free lean stream 118 comprising the unconverted oil feed sent to heavy oil hydrotreating unit 120 for the hydrotreating process generally meets one or more of the following: an API in the range of about −5 to about 15, a sulfur content in the range of about 0.7 to about 5 wt. %, a micro carbon residue (MCR) content of about 8 wt. % to about 35 wt. %, or a total content of Ni and V of less than about 150 ppm.

[0100] Hydrotreated effluent 124 from the hydrotreating process also generally meets one or more of the following: an API in the range of about 2 to about 18, a sulfur content in the range of about 0.05 wt. % to about 0.70 wt. %, a micro carbon residue content of about 3 wt. % to about 18 wt. %, or a total content of Ni and V of less than about 30 ppm. In addition, the HOHDT process conversion of sulfur is generally in the range of about 40% to about 95%, the MCR conversion is generally in the range of about 30% to 80% and the Ni+V metals conversion is generally in the range of about 50% to about 99%.

[0101] The heavy oil hydrotreating process generally comprises a hydrotreating catalyst selected from a demetallation catalyst, a desulfurization catalyst, or a combination thereof. In some embodiments, such catalysts may comprise a catalyst composition comprising about 5 vol. % to about 20 vol. % of a grading and demetallation catalyst, about 10 vol. % to about 30 vol. % of a transition-conversion catalyst, and about 50 vol. % to about 85 vol. % of a deep conversion catalyst. In some embodiments, a catalyst composition comprising about 10 to about 15 vol. % of a grading and demetallation catalyst, about 20 vol. % to about 25 vol. % of a transition-conversion catalyst, and about 60 vol. % to about 70 vol. % of a deep conversion catalyst. In another embodiment, the catalyst comprises about 100 vol % of deep conversion catalyst. The grading and demetallation catalyst, transition-conversion catalyst, and deep conversion catalyst may be layered in order to sequentially treat the unconverted oil stream.

[0102] Suitable catalysts for use as grading and demetallation catalyst, transition-conversion catalysts, and deep conversion catalysts are known in the art and described in various patents, including, for example, U.S. Pat. Nos. 5,215,955; 4,066,574; 4,113,661; 4,341,625; 5,089,463; 4,976,848; 5,620,592; and 5,177,047.

[0103] The transition and conversion catalyst provides moderate demetallation activity and metals uptake capacity, with moderate HDS and HDMCR (hydro-de-MCR, microcarbon residue) activity. Transition and conversion catalysts have intermediate pore volume, pore size and active metal content relative to grading and demetallation catalysts and deep conversion catalysts. The catalyst typically has a pore volume from about 0.5 cm3 / g to about 0.8 cm3 / g, a surface area from about 100 m2 / g to about 180 m2 / g, and a mean mesopore diameter from about 100× to about 200 Å, as measured by BET method. The active Mo content is typically from about 5 wt. % to about 9 wt. %, and the Ni content is typically from about 1.5 wt. % to about 2.5 wt. %.

[0104] The deep conversion catalyst converts the least reactive sulfur, nitrogen and MCR species to achieve deep catalytic conversion and meet a product target. Deep conversion catalysts have low demetallation activity and metals uptake capacity. The deep conversion catalyst has low pore volume, high surface area, small pore size and high metal level. The catalyst typically has a pore volume of about 0.7 cm3 / g or less, a surface area of greater than about 150 m2 / g, and a mean mesopore diameter greater than about 150 Å, as measured by the BET method. The active Mo content is typically greater than about 7.5 wt. %, and the Ni content is greater than about 2 wt. %.

[0105] The heavy oil hydrotreating reaction in heavy oil hydrotreating unit 120 produces hydrotreated effluent 124 comprising an upgraded heavy oil and a gaseous product stream 122 comprising light hydrocarbon gases produced in heavy oil hydrotreating unit 120 as well as excess hydrogen or other by-product gases. In some embodiments, an upgraded heavy oil can contain from about 10% to about 40% residual conversion, about 2 to about 15 degrees of API, and a lower amount of S / N / MCR / metals as compared to the unconverted oil. The light hydrocarbon gases can include, for example, methane, ethane, propane, ethylene, propylene, mixed butenes, or combinations of these. The light gas yield in heavy oil hydrotreating unit 120 is significantly lower than that in slurry hydroconversion unit 102. A portion or all of hydrotreated effluent 124 from heavy oil hydrotreating unit 120 can be recycled back to slurry hydroconversion unit 102 with optional fractionation before recycling. By recycling a portion of hydrotreated effluent 124, it will be easier to crack when being processed in slurry hydroconversion unit 102 as discussed above than an unconverted oil thereby producing less gaseous products such as light hydrocarbon gases thereby improving the yield of distillate products from the slurry hydroconversion process of the heavy oil feedstock.

[0106] In accordance with a non-limiting illustrative embodiment, a system for upgrading a heavy oil feedstock includes:

[0107] a slurry hydroconversion stage comprising one or more slurry hydroconversion reactors configured for hydroconverting the heavy oil feedstock in the presence of hydrogen and a slurry hydroconversion catalyst under slurry hydroconversion conditions, thereby producing a slurry hydroprocessing effluent comprising a gas product and a liquid / slurry product comprising upgraded material, unconverted oil, solid catalyst particles and solids formed during a hydroconversion reaction,

[0108] a first separation stage comprising one or more separators configured for separating the gas and upgraded material from the slurry hydroprocessing effluent, thereby producing a slurry stream,

[0109] a second separation stage comprising one or more solid-liquid separators configured for separating the slurry stream from the first separation stage into a solid-free lean stream comprising the unconverted oil and a solid-rich stream comprising the solid catalyst particles and the solids formed during the hydroconversion reaction,

[0110] a hydrotreating stage comprising a hydrotreating reactor configured for hydrotreating the solid-free lean stream comprising the unconverted oil in the presence of hydrogen and a hydrotreating catalyst under heavy oil hydrotreating conditions, thereby producing a hydrotreated effluent, and

[0111] a recycle line configured for recycling at least a portion of the hydrotreated effluent the back to the slurry hydroconversion stage.

[0112] Each of the foregoing illustrative embodiments is shown in FIGS. 2A and 2B. In each of the figures, particular units and process and product streams are identified as follows:

[0113] Process units: mixing unit 202, slurry hydrocracking reactor (208); hot high-pressure separator, HHPS (212); separator, low pressure slurry phase stripper, LPSPS (216); hot low-pressure separator, HLPS (222), pre-flash separator (234), slurry stripper (228); cross flow filtration system (240); vacuum tower (244); filter press (252) and heavy oil hydrotreater (258).

[0114] Process streams: heavy oil feedstock (201), vacuum tower bottoms effluent (250), hydrotreated effluent (260), slurry hydrocracking reactor feed (204); and hydrogen feed (206).

[0115] Process and / or product streams not specifically identified above but enumerated in the illustrative figures are intended to identify normal process and product streams such as streams 210, 214, 218, 220, 224, 226, 230, 230-1, 230-2, 232, 236, 242, 242-1, 242-2, 246, 248, 254, 256, 260-1, and 260-2 from such units and do not require further detail for the purposes herein.EXAMPLES

[0116] The following examples are provided to further illustrate the present method and its benefits. The examples are meant to be illustrative and not limiting.

[0117] Examples 1-2 are runs testing the hydroconversion process as implemented by the present disclosure and Comparative Example A is a run testing the hydroconversion process without using a Heavy Oil Hydrotreater Recycle.Example 1

[0118] This example illustrates the benefits of using a Heavy Oil Hydrotreater Recycle.

[0119] The properties of an Arab Light Vacuum Residuum (AL VR) feed used in this example are shown in Table 1.TABLE 1Feed PropertiesAPI Gravity8.5°Specific Gravity1.01Sulfur, wt. %4.060Nitrogen, ppm2639MCR, wt. %16.79Asphaltenes, wt. %6.2V, ppm54.2Ni, ppm16.7Fe, ppm6.05

[0120] An 18% unconverted oil from the hydrocracking slurry unit (as of the fresh AL VR feed rate) was run through a heavy oil hydrotreater (HOHDT) and 60% was recycled back to the slurry reactors. The operating conditions and results are summarized in Table 2.TABLE 2Base CaseHOHDT RecycleFeedAL VRAL VROperating ConditionsLHSV by VR, h−10.130.13CatalystISOSLURRY ®ISOSLURRY ®H2 to Reactors, SCFB50005000Reactors in Service33Reactor Temperature, ° F.816.7816.7Reactor Pressure, psig24502450HOHDT Temperature, ° F.—690-700HOHDT LHSV, h−1—0.115H2 to HOHDT, SCFB—5000Conversion, wt. %Sulfur86.189.7Nitrogen36.648.3MCR87.893.9Vanadium100.0100.0Nickel93.796.1VR95.697.1Gas-makeC12.24%2.18%C2 to C4 in gas7.34%7.32%

[0121] The results in Table 2 show that with HOHDT recycle, the VR conversion was 1.500 higher, while gas-make (C1 to C4 hydrocarbons) remains about the same.Example 2Recycle Until Extinction

[0122] The properties of the Vacuum Residuum (VR) feed used in this example are shown in Table 3.TABLE 3Feed PropertiesAPI Gravity7.90Specific gravity1.02Sulfur, wt. %4.213Nitrogen, ppm2618MCR, wt. %17.2Asphaltenes, wt. %7.3V, ppm51.3Ni, ppm16.2VR (1000° F.+), wt. %76.70HVGO (800° F.+), wt. %100.00VGO (650° F.+), wt. %100.00

[0123] A 20% unconverted oil from the hydrocracking slurry unit (as of the fresh VR feed rate) was run through a HOHDT. For recycle to extinction, all HOHDT effluent was recycled back to the slurry reactor. In this dataset, only a small bleed (about 1-2% fresh feed) was used for sampling purposes. The operating conditions and results are summarized in Table 4.TABLE 4Operating ConditionsSlurry ReactorTemperature, ° F.810Pressure, psig2300LHSV, h−10.103HOHDT RecycleTemperature, ° F.700Pressure, psig2330Conversion, wt. %VR (1000° F.+)99.5

[0124] The results in Table 4 show a VR (1000° F.+) conversion of 99.5%. Such high conversion would be difficult to obtain without HOHDT recycle. Full conversion may be obtained if needed.Comparative Example A

[0125] This example illustrates the significant increase in gas-make (C1 to C4 light hydrocarbons) without using a Heavy Oil Hydrotreater Recycle as in Example 1.

[0126] The properties of a Middle East Vacuum Residuum (ME VR) feed used in this example are shown in Table 5.TABLE 5Feed PropertiesAPI Gravity4.9Specific Gravity1.04Sulfur, wt. %5.07Nitrogen, ppm0.46MCR, wt. %21.82Asphaltenes, wt. %11.01V, ppm125.3Ni, ppm41.1Fe, ppm15.0

[0127] The operating conditions used for the base case include around 2450 psig, 806° F. (430° C.) and 0.115 hr−1 LSVH. While maintaining other reaction conditions the same, the slurry hydrocracking reactor temperature was increased by 2° C. / 4° F. in the test case. The operating conditions and conversion results are summarized in Table 6.TABLE 6Base CaseTest CaseVR Feed TypeME VRME VRLHSV by Total Feed, hr−10.1150.115Reactor Temperature, ° F. / ° C.806 / 430810 / 432Conversion, wt. %Sulfur86.288.1Nitrogen40.443.8MCR88.192.2Vanadium99.499.6Nickel94.095.7VR93.595.7Yield49.0%47.4%Gas-make (C1-C4 in gas)8.32%9.45%

[0128] The results in Table 6 show that VR conversion increased from 93.5% to 95.7%. The gas-make (C1-C4) in gas also increased from 8.32% to 9.45%. By gaining 2.2% in VR conversion, the gas increased by 1.13%, or approximately 50% of additional converted VR was turned into gas, instead of liquid products.

[0129] According to an aspect of the present disclosure, a process comprises:

[0130] receiving, in a heavy oil hydrotreating unit, a solid-free lean stream comprising unconverted oil processed from a heavy oil feedstock in a slurry hydroconversion reactor,

[0131] hydrotreating the solid-free lean stream comprising the unconverted oil in the presence of hydrogen and a hydrotreating catalyst in the heavy oil hydrotreating unit under heavy oil hydrotreating conditions, thereby producing a hydrotreated effluent, and

[0132] recycling at least a portion of the hydrotreated effluent to the slurry hydroconversion reactor.

[0133] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the process further comprises exposing a heavy oil feedstock and the portion of the hydrotreated effluent recycled to the slurry hydroconversion reactor to a slurry hydroconversion catalyst in the presence of hydrogen under slurry hydroconversion conditions in a reaction zone of the slurry hydroconversion reactor, thereby producing a slurry hydroconversion effluent comprising a gas product and a slurry product comprising upgraded heavy oil, unconverted oil, solid catalyst particles and solids formed during a hydroconversion reaction.

[0134] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the process further comprises separating the gas product from the slurry hydroconversion effluent and separating the upgraded heavy oil from the slurry product of the slurry hydroconversion effluent, thereby producing a slurry stream comprising the unconverted oil, the solid catalyst particles and the solids formed during the hydroconversion reaction.

[0135] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the process further comprises passing the slurry stream to one or more solid-liquid separators, thereby producing another solid-free lean stream comprising the unconverted heavy oil and a solid-rich stream comprising the solid catalyst particles and the solids formed during the hydroconversion reaction.

[0136] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the one or more solid-liquid separators comprise a cross flow filtration system.

[0137] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the process further comprises recycling a portion of the solid-rich stream to the slurry hydroconversion reactor.

[0138] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the solid-free lean stream comprising the unconverted oil is obtained from one of atmospheric residuum, vacuum residuum, tar from a solvent deasphalting unit, atmospheric gas oil, vacuum gas oil, deasphalted oil, oil derived from tar sands or bitumen, oil derived from coal, heavy crude oil, oil derived from recycled oil wastes and polymers, or a combination thereof.

[0139] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the heavy oil hydrotreating conditions include a reactor pressure of about 1500 psig to about 3000 psig, an average reactor temperature of about 360° C. to about 410° C., a hydrogen-to-oil ratio of about 3000 SCFB to about 6000 SCFB; and a hydrogen consumption of about 300 SCFB to about 1200 SCFB.

[0140] According to another aspect of the present disclosure, a process comprises:

[0141] exposing a heavy oil feedstock to a slurry hydroconversion catalyst under slurry hydroconversion conditions in a reaction zone of a slurry hydroconversion reactor in the presence of hydrogen, thereby producing a slurry hydroconversion effluent comprising a gas product and a slurry product comprising upgraded heavy oil, unconverted oil, solid catalyst particles and solids formed during a hydroconversion reaction,

[0142] separating the slurry product from the gas product of the slurry hydroconversion effluent, thereby producing a slurry stream comprising the unconverted oil, the solid catalyst particles and the solids formed during the hydroconversion reaction,

[0143] separating the upgraded heavy oil from the slurry stream of the slurry hydroconversion effluent using one or more solid-liquid separators, thereby producing a solid-free lean stream comprising the unconverted oil and a solid-rich stream comprising the solid catalyst particles and the solids formed during the hydroconversion reaction,

[0144] hydrotreating the solid-free lean stream comprising the unconverted oil in the presence of hydrogen and a hydrotreating catalyst in a heavy oil hydrotreating unit under heavy oil hydrotreating conditions, thereby producing a hydrotreated effluent, and

[0145] recycling at least a portion of the hydrotreated effluent to the reaction zone of the slurry hydroconversion reactor.

[0146] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the gas product comprises light hydrocarbon gases and hydrogen, and the process further comprises:

[0147] separating the hydrogen from the gas product, and

[0148] recycling the hydrogen back to the slurry hydroconversion reactor.

[0149] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the process further comprises passing the solid-free lean stream comprising the unconverted oil to a fractionator.

[0150] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the one or more solid-liquid separators comprise a cross flow filtration system.

[0151] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the process further comprises recycling a portion of the solid-rich stream to the slurry hydroconversion reactor.

[0152] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the process further comprises exposing another heavy oil feedstock and the portion of the hydrotreated effluent recycled to the slurry hydroconversion reactor to the slurry hydroconversion catalyst in the presence of hydrogen under slurry hydroconversion conditions in the reaction zone of the slurry hydroconversion reactor, thereby producing another slurry hydroconversion effluent comprising a gas product and a slurry product comprising upgraded heavy oil, unconverted oil, solid catalyst particles and solids formed during a hydroconversion reaction.

[0153] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the process further comprises separating the gas product from the other slurry hydroconversion effluent and separating the upgraded heavy oil from the slurry product of the other slurry hydroconversion effluent.

[0154] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the solid-free lean stream comprising the unconverted oil is obtained from one of atmospheric residuum, vacuum residuum, tar from a solvent deasphalting unit, atmospheric gas oil, vacuum gas oil, deasphalted oil, oil derived from tar sands or bitumen, oil derived from coal, heavy crude oil, oil derived from recycled oil wastes and polymers, or a combination thereof.

[0155] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the heavy oil hydrotreating conditions include a reactor pressure of about 1500 psig to about 3000 psig, an average reactor temperature of about 360° C. to about 410° C., a hydrogen-to-oil ratio of about 3000 SCFB to about 6000 SCFB; and a hydrogen consumption of about 300 SCFB to about 1200 SCFB.

[0156] According to yet another aspect of the present disclosure, a system comprises:

[0157] a heavy oil hydrotreating unit comprising a heavy oil hydrotreating reactor configured for hydrotreating a solid-free lean stream comprising unconverted oil processed from a heavy oil feedstock in a slurry hydroconversion reactor, in the presence of hydrogen and a hydrotreating catalyst under heavy oil hydrotreating conditions, thereby producing a hydrotreated effluent,

[0158] a recycle line configured for recycling at least a portion of the hydrotreated effluent, and

[0159] a slurry hydroconversion unit comprising one or more slurry hydroconversion reactors configured for hydroconverting a heavy oil feedstock and the portion of the hydrotreated effluent recycled from the heavy oil hydrotreating unit in the presence of hydrogen and a slurry hydroconversion catalyst under slurry hydroconversion conditions, thereby producing a slurry hydroconversion effluent comprising a gas product and a slurry product comprising upgraded heavy oil, unconverted oil, solid catalyst particles and solids formed during a hydroconversion reaction.

[0160] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the system further comprises:

[0161] a first separation unit comprising one or more separators configured for separating the gas product and the upgraded heavy oil from the slurry hydroconversion effluent, thereby producing a slurry stream comprising the unconverted oil, the solid catalyst particles and the solids formed during the hydroconversion reaction, and

[0162] a second separation unit comprising one or more solid-liquid separators configured for separating the slurry stream, thereby producing a solid-free lean stream comprising the unconverted oil and a solid-rich stream comprising the solid catalyst particles and the solids formed during the hydroconversion reaction.

[0163] In one or more additional illustrative embodiments, as may be combined with the preceding paragraphs, the one or more solid-liquid separators are configured for cross flow filtration.

[0164] Various features disclosed herein are, for brevity, described in the context of a single embodiment, but may also be provided separately or in any suitable sub-combination. All combinations of the embodiments are specifically embraced by the illustrative embodiments disclosed herein just as if each and every combination was individually and explicitly disclosed. In addition, all sub-combinations listed in the embodiments describing such variables are also specifically embraced by the present disclosure and are disclosed herein just as if each and every such sub-combination was individually and explicitly disclosed herein.

[0165] While the above description contains many specifics, these specifics should not be construed as limitations of the invention, but merely as exemplifications of preferred embodiments thereof. Those skilled in the art will envision many other embodiments within the scope and spirit of the invention as defined by the claims appended hereto.

Claims

1. A process, comprising:receiving, in a heavy oil hydrotreating unit, a solid-free lean stream comprising unconverted oil processed from a heavy oil feedstock in a slurry hydroconversion reactor;hydrotreating the solid-free lean stream comprising the unconverted oil in the presence of hydrogen and a hydrotreating catalyst in the heavy oil hydrotreating unit under heavy oil hydrotreating conditions, thereby producing a hydrotreated effluent; andrecycling at least a portion of the hydrotreated effluent to the slurry hydroconversion reactor.

2. The process according to claim 1, further comprising exposing a heavy oil feedstock and the portion of the hydrotreated effluent recycled to the slurry hydroconversion reactor to a slurry hydroconversion catalyst in the presence of hydrogen under slurry hydroconversion conditions in a reaction zone of the slurry hydroconversion reactor, thereby producing a slurry hydroconversion effluent comprising a gas product and a slurry product comprising upgraded heavy oil, unconverted oil, solid catalyst particles and solids formed during a hydroconversion reaction.

3. The process according to claim 2, further comprising separating the gas product from the slurry hydroconversion effluent and separating the upgraded heavy oil from the slurry product of the slurry hydroconversion effluent, thereby producing a slurry stream comprising the unconverted oil, the solid catalyst particles and the solids formed during the hydroconversion reaction.

4. The process according to claim 3, further comprising passing the slurry stream to one or more solid-liquid separators, thereby producing another solid-free lean stream comprising the unconverted heavy oil and a solid-rich stream comprising the solid catalyst particles and the solids formed during the hydroconversion reaction.

5. The process according to claim 4, wherein the one or more solid-liquid separators comprise a cross flow filtration system.

6. The process according to claim 4, further comprising recycling a portion of the solid-rich stream to the slurry hydroconversion reactor.

7. The process according to claim 1, wherein the solid-free lean stream comprising the unconverted oil is obtained from one of atmospheric residuum, vacuum residuum, tar from a solvent deasphalting unit, atmospheric gas oil, vacuum gas oil, deasphalted oil, oil derived from tar sands or bitumen, oil derived from coal, heavy crude oil, oil derived from recycled oil wastes and polymers, or a combination thereof.

8. The process according to claim 1, wherein the heavy oil hydrotreating conditions include a reactor pressure of about 1500 psig to about 3000 psig, an average reactor temperature of about 360° C. to about 410° C., a hydrogen-to-oil ratio of about 3000 SCFB to about 6000 SCFB; and a hydrogen consumption of about 300 SCFB to about 1200 SCFB.

9. A process, comprising:exposing a heavy oil feedstock to a slurry hydroconversion catalyst under slurry hydroconversion conditions in a reaction zone of a slurry hydroconversion reactor in the presence of hydrogen, thereby producing a slurry hydroconversion effluent comprising a gas product and a slurry product comprising upgraded heavy oil, unconverted oil, solid catalyst particles and solids formed during the hydroconversion reaction;separating the slurry product from the gas product of the slurry hydroconversion effluent, thereby producing a slurry stream comprising the unconverted oil, the solid catalyst particles and the solids formed during the hydroconversion reaction;separating the upgraded heavy oil from the slurry stream of the slurry hydroconversion effluent using one or more solid-liquid separators, thereby producing a solid-free lean stream comprising the unconverted oil and a solid-rich stream comprising the solid catalyst particles and the solids formed during the hydroconversion reaction;hydrotreating the solid-free lean stream comprising the unconverted oil in the presence of hydrogen and a hydrotreating catalyst in a heavy oil hydrotreating unit under heavy oil hydrotreating conditions, thereby producing a hydrotreated effluent; andrecycling at least a portion of the hydrotreated effluent to the reaction zone of the slurry hydroconversion reactor.

10. The process according to claim 9, wherein the gas product comprises light hydrocarbon gases and hydrogen, and the process further comprises:separating the hydrogen from the gas product; andrecycling the hydrogen back to the slurry hydroconversion reactor.

11. The process according to claim 9, further comprising passing the solid-free lean stream comprising the unconverted oil to a fractionator.

12. The process according to claim 9, wherein the one or more solid-liquid separators comprise a cross flow filtration system.

13. The process according to claim 9, further comprising recycling a portion of the solid-rich stream to the slurry hydroconversion reactor.

14. The process according to claim 9, further comprising exposing another heavy oil feedstock and the portion of the hydrotreated effluent recycled to the slurry hydroconversion reactor to the slurry hydroconversion catalyst in the presence of hydrogen under slurry hydroconversion conditions in the reaction zone of the slurry hydroconversion reactor, thereby producing another slurry hydroconversion effluent comprising a gas product and a slurry product comprising upgraded heavy oil, unconverted oil, solid catalyst particles and solids formed during the hydroconversion reaction.

15. The process according to claim 14, further comprising separating the gas product from the other slurry hydroconversion effluent and separating the upgraded heavy oil from the slurry product of the other slurry hydroconversion effluent.

16. The process according to claim 9, wherein the solid-free lean stream comprising the unconverted oil is obtained from one of atmospheric residuum, vacuum residuum, tar from a solvent deasphalting unit, atmospheric gas oil, vacuum gas oil, deasphalted oil, oil derived from tar sands or bitumen, oil derived from coal, heavy crude oil, oil derived from recycled oil wastes and polymers, or a combination thereof.

17. The process according to claim 9, wherein the heavy oil hydrotreating conditions include a reactor pressure of about 1500 psig to about 3000 psig, an average reactor temperature of about 360° C. to about 410° C., a hydrogen-to-oil ratio of about 3000 SCFB to about 6000 SCFB;and a hydrogen consumption of about 300 SCFB to about 1200 SCFB.

18. A system, comprising:a heavy oil hydrotreating unit comprising a heavy oil hydrotreating reactor configured for hydrotreating a solid-free lean stream comprising unconverted oil processed from a heavy oil feedstock in a slurry hydroconversion reactor, in the presence of hydrogen and a hydrotreating catalyst under heavy oil hydrotreating conditions, thereby producing a hydrotreated effluent;a recycle line configured for recycling at least a portion of the hydrotreated effluent; anda slurry hydroconversion unit comprising one or more slurry hydroconversion reactors configured for hydroconverting a heavy oil feedstock and the portion of the hydrotreated effluent recycled from the heavy oil hydrotreating unit in the presence of hydrogen and a slurry hydroconversion catalyst under slurry hydroconversion conditions, thereby producing a slurry hydroconversion effluent comprising a gas product and a slurry product comprising upgraded heavy oil, unconverted oil, solid catalyst particles and solids formed during a hydroconversion reaction.

19. The system according to claim 18, further comprisinga first separation unit comprising one or more separators configured for separating the gas product and the upgraded heavy oil from the slurry hydroconversion effluent, thereby producing a slurry stream comprising the unconverted oil, the solid catalyst particles and the solids formed during the hydroconversion reaction; anda second separation unit comprising one or more solid-liquid separators configured for separating the slurry stream, thereby producing a solid-free lean stream comprising the unconverted oil and a solid-rich stream comprising the solid catalyst particles and the solids formed during the hydroconversion reaction.

20. The system according to claim 19, wherein the one or more solid-liquid separators are configured for cross flow filtration.

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