Hydrocarbon resid processing and visbreaking steam cracker feed

Raw material for cassia residue oil treatment and visbreaking steam cracker

[0001] Related applications

[0002] This application claims the rights and priority of the US provisional patent application number 60/728,640 (2005Β125) filed on October 20, 2005, and the US provisional patent application number 60/ filed on June 14, 2006 813, 555 (2006Β101) rights and interests.

Technical field

[0003] The present invention relates to a method for preparing olefin billets from crude oil or its residual oil-containing fractions.

Background technique

[0004] Thermal cracking of billets is a petrochemical process widely used in the preparation of olefin billets such as ethylene, propylene, butenes, butadiene and aromatic billets such as benzene, toluene and xylenes. Each of these compounds is a valuable industrial product. For example, light olefin blanks can be oligomerized (for example, oligomerized as lubricant base oil), polymerized (for example, polymerized into polyethylene, polypropylene, and other plastics) and/or functionalized (for example, used to form acids, alcohols, aldehydes, etc.) , The listed materials all have well-known intermediate and/or end uses. One method of thermal cracking is steam cracking, which involves cracking billets in the presence of hydrogen and/or hydrogen-containing components such as steam.

[0005] The starting materials of the conventional olefin blank production device as described above have undergone a large amount (and high cost) processing before reaching the olefin blank production device. Normally, whole crude oil is steamed or otherwise divided or cracked into multiple parts (parts) such as gasoline, kerosene, naphtha, gas oil (vacuum gas oil and atmospheric gas oil), etc. (including high boiling point residues) The oil ("residual oil")) is desalinated first. Residual oil fractions usually have a boiling point above 650 °F (343Ό) at atmospheric pressure. Usually after desalination and removal of residual oil content, any such content except 650 T + (343°C +) residual oil can be transported to the steam cracker or olefin billet production unit as the raw material of the unit.

[0006] Generally, in steam cracking, the raw materials for steam cracking such as naphtha, gas oil or other crude oil containing no residual oil content (they can be obtained by steaming or otherwise separating whole crude oil, for example) Introduced into a steam cracker, usually mixed with steam. Ordinary steam cracking uses a pyrolysis furnace that usually has two main sections: a convection section and a radiant section. In an ordinary pyrolysis furnace, the raw material enters the convection section of the pyrolysis furnace that is not strictly strict as a liquid (except for the light raw materials entering as steam), where it passes indirect contact with the hot flue gas from the radiant section. The option is heated and vaporized by direct contact with steam. The vaporized feedstock and steam mixture (if present) is then introduced through a jumper into the radiant section, where it is rapidly heated to a strict cracking temperature, for example, 1450 °F (788Ό) to 1550, at a pressure of typically 10-30 psig °F (843Ό) range to provide thorough thermal cracking of the feed stream. The resulting product containing the olefin billet leaves the pyrolysis furnace for further downstream separation and processing.

[0007] After cracking, the effluent of the pyrolysis furnace contains various gas blanks (which are, for example, saturated, monounsaturated and polyunsaturated, and may be aliphatic and/or aromatic), And contains a lot of molecular hydrogen. The cracked products are then further processed, for example, in an olefin production unit to produce the various independent high-purity streams mentioned above as equipment products, namely, hydrogen, light olefins, ethylene, propylene and butenes, as well as aromatics, and other products. Such as pyrolysis gasoline.

[0008] Because the world's demand for light olefin billets is increasing, and useful crude oil resources are consumed, it is necessary to use heavy crude oil (that is, those with a higher proportion of residual oil), which requires increased capital investment to process And deal with refining by-products and purchase higher-grade raw materials. I very much hope to have the ability to use lower cost, heavy crude oil more effectively and produce

A more excellent method of product mixture of light olefin billets.

[0009] It has been proposed to improve the grade of certain crude oils by first hydrotreating the feedstock before steam cracking. For example, US Patent Nos. 3,855, 113 and 6, 190, 533 relate to a method that includes passing the feedstock through a hydrotreating zone and then through a steam cracking zone. However, there is no case where whole crude oil or residual oil-containing fractions are directly transported to the hydroprocessing zone. See also GB2071133 and Erdoel & Kohle, Erdgas, Petrochemie (1981), 34(1), 443-60

[0010] Conventional residual oil hydrotreating or "residue hydrorefining" is a known method for improving the quality of a part of crude oil containing residual oil. Hydrogenated liquid and vapor products (but not residual oil products) obtained from residual oil hydrofining are usually divided into more valuable logistics, such as fuel oil, diesel, heating oil, jet fuel (jet), kerosene, Gasoline, LPG and flue gas. All these materials can themselves be used as fuels and/or as intermediates for the production of petrochemical products, for example. For example, fuel oil can also be cracked to form lower boiling point fuels such as gasoline, LPG and fuel gas and/or petrochemical products ethylene, propylene and butanes. Residual oil fractions are usually low-value products. However, after the hydroprocessing and before or during the further distillation of the residual oil stream, the crude oil fraction containing the residual oil can be converted, deasphalted or otherwise treated.

[0011] US 3,898,299 discloses a method for removing residual oil and producing alkene blanks from non-residual oil and low boiling point blanks. The atmospheric residual oil obtained by steaming is subjected to hydrotreating and the liquid hydrotreating effluent is directly fed to the pyrolysis zone in the presence of steam, where the steamed residues enter and maintain the thermal cracking conditions Before the next pyrolysis zone, unvaporized raw materials are removed as residual components in the separation zone." However, the '299 reference only teaches conventional hydroprocessing and thermal steam cracking of the top stream without residual oil, and does not properly propose or teach how to use the residual oil-containing effluent from a residual oil hydroprocessing unit as steam cracking. The raw material of the device. The '299 patent generally requires the separation and removal of the 650 T+ (343Ό) boiling point fraction from the treated hydrotreater effluent before steam cracking. Only the excrement is processed into olefin blanks. Those skilled in the art are well aware of the practical difficulties of steam cracking raw materials containing residual oil, including equipment fouling of the ordinary equipment of the '299 patent. Residual oil hydroprocessing is a known method for upgrading residual oil into fuels such as fuel oil, diesel, heating oil, jet fuel, kerosene, gasoline, LPG, and fuel gas. These materials can be used as fuels and/or intermediates for the production of petrochemical products, for example.

[0012] Other patents related to the cracking of heavy feedstocks include Wernicke's US Patent No. 4,257,871; Soonawala's US Patent No. 4, 065, 379; Franck's US Patent No. 4, 180, 453; and Wernicke's US Patent No. 4, 210, 520. However, none of the above-mentioned patents fully teaches how to steam crack a residual oil-containing billet stream to produce alkene billet.

[0013] In US 4, 257, 871, the use of vacuum residual oil is used to produce olefin greens by the following method: firstly separate the bitumen contained therein, blend the obtained bitumen-poor bitumen with lighter bitumen, and then blend The blend is subjected to conventional catalytic hydrogenation, followed by thermal cracking. See also US4, 297, 204.

[0014] Japanese Kokai patent application Sho58 [1983]-98387 relates to a method for preparing gas olefin billet and mononuclear aromatic billet, which is characterized by hydrogenating crude oil with hydrogen and a hydrogenation catalyst, followed by thermal cracking. In embodiments, the hydrogenated crude oil can be distilled or flashed to separate the individual components, and the top stream can be fed to the thermal cracking process. See also Japanese Kokai patent application Sho58 [1983]-005393 and Japanese Kokai patent application Sho57 [1982]-212294.

[0015] US 6,303, 842 teaches a method for preparing olefins by thermal steam cracking residual oil containing short boiling range residual oil with a boiling point higher than 565° C., wherein at least 3 wt% of short boiling range residual oil has Boiling point higher than or equal to 650 °C. The raw materials are prepared by ordinary hydroprocessing. Other significant references include US Patent Nos. 3,855,113; 4, 057, 490; 4, 179, 355 and 6,743, 96L. Other patents related to the cracking of heavy feedstocks include Wernicke's US

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Patent No. 4,257,871; Soonawala's US Patent No. 4, 065, 379; Franck's US Patent No. 4, 180, 453; and Wernicke's US Patent No. 4, 210, 520.

[0016] WO2004/005431 discloses a method of steam cracking certain feedstocks containing residual oil, in which a large amount of unconverted liquid residual oil is removed before steam cracking. The 5431 invention does not disclose or teach hydrogenation as a method for improving the quality of heavy, acidic crude oil and residual oil feedstocks (including residual oil content), so that whole crude oil including residual oil content can be steam cracked and converted It is a petrochemical product. Heavy, acidic feedstocks do not contain high concentrations of linear alkane billets, and they are known to constitute the highest quality steam cracker feedstock. The atmospheric and vacuum residual oil content of crude oil containing >2.0wt% sulfur almost always has a hydrogen content of <12.5wt%, and usually they have a hydrogen content of <11.Owt%. As we all know, ordinary residual oil hydrotreating produces products that are very prone to fouling.

[0017] There is a need in the art for devices and methods for economically processing heavy residual oil-containing whole crude oil and their residual oil-containing stocks to prepare alkene stocks, aromatic stocks and other valuable petrochemical products. All the prior art prior to the present invention has deficiencies, shortcomings or undesirable aspects.

Summary of the invention

[0018] The inventors have surprisingly discovered that by integrating at least one hydrogenation step, at least one visbreaking step, and at least one thermal cracking step, it is possible to use residual oil hydrotreating with increased stringency and thermal integration with a steam cracker. Preparation of useful products, such as olefin billets and/or aromatic compounds.

[0019] The present invention provides a method by which a hydrotreating effluent containing residual oil content can be used as a steam cracker feedstock. The inventor also discovered that crude oil or its residual oil-containing fractions can be hydrotreated for use as a steam cracker feedstock. The hydrotreated residual oil-containing feedstock can be steam cracked to produce useful products such as olefin and/or aromatic compounds. The present invention relates to a method for integrating the hydrogenation and steam cracking of residual oil-containing materials to obtain olefin green products.

[0020] One embodiment of the present invention is a method for preparing olefin billets from a raw material containing crude oil or crude oil containing residual oil. The method includes a hydrotreating step, a visbreaking step, and a thermal cracking step. The method and device are capable of removing only the heaviest and least desirable residual oil components of the feed stream, and basically only the vaporized components (which include the vaporized components obtained from the residual oil) are transported to the steam crackerofradiant section.

[0021] In a preferred embodiment of any of the above methods, there is a visbreaking step before the steam cracking step and/or there is a vapor-liquid separation device integrated with the pyrolysis furnace, such as a visbreaker. The visbreaking process can be carried out in an integrated vapor-liquid separation device, which eliminates the need for a separate ordinary visbreaking process or equipment.

[0022] Another preferred embodiment is a method comprising splitting a portion of the residual oil group in the hydrogenation step, obtaining the effluent from the residual oil hydrotreating unit, visbreaking the effluent, and reducing the The top product of the viscracking step is transported to the radiant section of the steam cracker. Here again, the visbreaking can be carried out in an integrated vapor-liquid separation device or in a visbreaker separate from the steam cracker.

[0023] In a preferred embodiment, the method further includes an integrated separation step, such as removing the asphaltenes and/or residuals from the feedstock by using a flash tank before transporting the feedstock to the radiant section of the steam cracker unit The boiling point is above 1050°F (approximately 566°C), preferably only those with a boiling point higher than 1100°F (approximately 593°C). Surprisingly, this can make the fouling rate equal to or better than the fouling rate of the VGO steam cracker feedstock. Preferably, at least one flash tank or other flash equipment such as an in-line choke, or orifice is provided to reduce the pressure in the hydrotreater effluent and cause some liquid to be converted to vapor. Preferably, make the flashing device and the steam

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Feed integration of cracker pyrolysis unit. Integration refers to heat integration, so that heat can be obtained from one or more steps of the process (for example, during hydroprocessing, convection section preheating) and/or from the steam cracker for conversion, cracking, flashing and Separation process. In a preferred embodiment, the pressure of the effluent of the hydrotreater is flashed off or reduced, which is at least one time before or during the separation. Flashing also includes the possibility of introducing the effluent into a vacuum.

[0024] In another preferred embodiment, the present invention includes a method for preparing a raw material containing residual oil for steam cracking. The method of the present invention in one aspect includes hydrotreating the feedstock to hydrogenate the feedstock, thereby improving the hydrogen saturation of the cracked effluent. The method of the present invention further includes thermally cracking the undesirable effluent by further processing the hydrotreater effluent containing residual oil in a visbreaker and in a vapor-liquid separator (for example, in a visbreaking separation process The one used) recovers the improved residual oil-containing vapor effluent obtained from the visbreaking process to improve the hydrogenated residual oil-containing hydrotreater effluent. The present invention includes further improvements by visbreaking and/or separating visbreaking treated materials in a visbreaker and/or vapor-liquid separator integrated with a steam cracker, more preferably with a convection section of the steam cracker The quality of raw materials.

[0025] In one embodiment of the various embodiments of the present invention, wherein the effluent is obtained from a residual oil hydroprocessing unit, the feed stream fed to the residual oil hydroprocessing unit includes crude oil without fraction or containing Crude oil is divided into residual oil. In another embodiment, the hydroprocessing is performed using at least one fixed bed hydrogenation reactor, boiling reactor or fluidized hydrogenation reactor before feeding to the pyrolysis unit.

[0026] In other embodiments, the feedstock to be hydrotreated includes one or more of recycled steam cracker tar, heavy crude oil, or topped crude oil, and the feedstock to be steam cracked includes recycle of hydrotreating Steam cracker tar, heavy crude oil or topped crude oil. In another preferred embodiment, the hydrogen source for hydroprocessing is from remote methane.

[0027] Some preferred embodiments also include a combination of two or more of the above embodiments (including preferred embodiments). In yet another preferred embodiment, the raw material is desalted or undesalted whole crude oil, or the product of a pipeline distillation tank in an oil refinery, or a chemical intermediate stream containing asphaltenes or residual oil, such as atmospheric residual oil or vacuum residual oil. Oil, or steam cracked tar, is hydrotreated using a fixed bed hydrogenation reactor or boiling or fluidized hydrogenation reactor before being fed to a pyrolysis unit with integrated vapor-liquid separation equipment.

[0028] The present invention also relates to a system comprising a hydrotreating unit, a pyrolysis unit and at least one vapor-liquid separation device for visbreaking, wherein the vapor-liquid separation device is advantageously integrated with the pyrolysis unit, and also relates to a system comprising A method for raw material feeding of residual oil to obtain products containing light olefin slabs (one or more C2-C6 olefins slabs). In a preferred embodiment, the system further includes a steam reformer for converting methane to hydrogen to provide hydrogen to the hydrotreating unit. An object of the present invention is to supply residual oil as a preferred feedstock to olefin billet producers, so that low-quality crude oil feedstocks can be used. Another object of the present invention is to increase the hydrogen content of the steam cracker feedstock while minimizing the increase in the residual oil content of the feedstock.

[0029] These and other objectives, features and advantages can be made clear with reference to the following detailed description, preferred embodiments, examples and appended claims.

Description of the drawings

[0030] In all the drawings, reference numerals, labels, or other marks that indicate parts or process components are used to indicate the same parts or components.

[0031] FIGS. 1-6 are process flow diagrams illustrating certain exemplary embodiments of the present invention.

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Detailed ways

[0032] In one embodiment, the residual oil-containing, initial thermal cracking effluent (which includes those residual oils having a boiling point of less than 1050 T (approximately 566Ό)) from a hydrotreater, preferably a residual oil hydrotreater Those residual oils with boiling points below 1100 T (approximately 593 Γ) are preferably separated and cracked further, for example in a visbreaker/separator, and used as a feedstock for a steam cracker or other pyrolysis unit. In the pyrolysis unit, the vaporized fractions are converted into desired products, which include olefin billets. The terms pyrolysis unit and steam cracker have the same meaning here; all refer to the devices commonly referred to as steam crackers, even if steam is optional.

[0033] According to the present invention, the crude oil containing residual oil or its fraction is hydrotreated. Generally, the residual oil hydrotreatment according to the present invention can be carried out at a temperature of at least 600°F (315°F), preferably at least 650°F (343°F), more preferably at least 750°F (399°F). Preferably, the pressure is at least ISOOpsigo. The purpose is to initiate thermal cracking of at least a portion of the residual oil at 650°F + (343°C +) in the hydrogenation step, such as initial thermal cracking. Such processing of heavy crude oil or heavy residual oil may generally require a temperature of at least 750 °F (399°C+) to initiate thermal cracking of light residual oil. Therefore, in some embodiments of the method of the present invention, the initial thermal cracking temperature of the hydrotreater unit is at least 750°F (399°C), or at least 780°F (451°C), in other embodiments, The temperature must be at least 800 °F (427°C). The preferred processing temperature range may be 650°F (343Ό) to U 900°F (482°C). According to other alternative embodiments of the method of the present invention, the hydroprocessing can be performed at 500°F (260°C) to 900°F (482°C), preferably 650°F (343°C) to 900°C. F (482°C), More preferably 700 °F (371 °C) to 900 °F (482 °C), more preferably 750 °F (399 °C) to 900 °F (482 °C), still more preferably 750 °F (399Ό) to Performed at a temperature of 800 °F (427°C). In some embodiments, the preferred pressure is 500-10,000 psig, preferably 1000-4000 psig, still more preferably 1500-3000 psig_oThe selected temperature can be changed according to the composition and conditions of the raw material. The preferred liquid hourly space velocity can be 0.1-5, preferably 0.25-1. The hydrogen supply rate (make-up and recycle hydrogen) in the hydroconversion zone can be 500-20, 000 standard cubic feet per barrel of raw material, Preferably 2,000-5,000 standard cubic feet per barrel. The hydroprocessing can be carried out using one zone or multiple hydroprocessing zones, for example, two or more hydroprocessing zones in parallel or in series. For example, in one embodiment, the first zone can include a first catalyst, which can be designed to accumulate most of the metals removed from the feedstock, and the second zone in series can include a second catalyst, which can be designed for Maximize the removal of heteroatoms and hydrogenation of aromatics. In another embodiment, the first catalyst can be designed to accumulate most of the metals removed from the feedstock, the second zone with the second catalyst can be designed to remove heteroatoms to the greatest extent, the second zone with the third catalyst The three zones can be designed to increase the hydrogenation of aromatic billets. The first and second catalysts can be piped in reactors connected in series, or can be loaded in series in the same zone. The design details do not become a critical part of the invention, because it only concerns the residual oil hydrotreating unit.

[0034] The catalyst used in a typical industrial hydroconversion zone is composed of a material with hydrogenation-dehydrogenation activity and an amorphous carrier. Exemplary amorphous supports include alumina, silica-alumina, silica, aluminum oxide, or titanium dioxide. The hydrogenation-dehydrogenation component of the catalyst preferably includes at least one hydrogenation component selected from group VI metals and group VI metal compounds and at least one hydrogenation component selected from group VIII metals and group VIII metal compounds. Preferred combinations of hydrogenation components include nickel sulfide and aluminum sulfide, cobalt sulfide and aluminum sulfide, cobalt and aluminum, and nickel and duck. The catalyst used in the present invention can also be composed of a material with hydrogenation-dehydrogenation activity that is not formulated with an amorphous carrier. Exemplary catalysts include Nebula.

[0035] According to the present invention, the residual oil hydrotreating may preferably be performed at a temperature and pressure that are stricter than that of ordinary hydroprocessing methods. In one embodiment, the hydrotreating can preferably be above 650°F (343°C) and up to a temperature at which significant billet cracking occurs during the hydrogenation process, such as 750°F (399°C) to 800°F (427°C). )get on. This not only produces hydrogenated residual oil components, but also splits or decomposes most of the residual oil groups into light weight fractions. Lightweight and injected steam

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Together, it contributes to the conversion, cracking and further vaporization and heat treatment of steam in the steam cracker, such as the cracker pipeline. [0036] Residual oil hydroprocessing includes essentially any method that results in the hydrogenation of residual oil and/or residual oil-containing fractions, and includes, but is not limited to, commercially available residual oil hydroprocessing technologies. Examples of these commercially available methods are the Η-Oil method, the Chevron RDS, VRDS, OCR and LC-Fining methods, the HYVAHL method, and the ENI-Snamprogetti EST method. Suitable hydrotreating methods may include, for example, a fixed bed catalyst system, a fluidized bed system, a fluidized bed system, and/or a combination thereof. The hydrotreating used herein also includes some mild cracking of the 650 T + (343°C +) residual oil component of the raw material, preferably even from 650°F (343°C) to 1100°F (593°C) ) Boiling point, more preferably 650°F (343°C) to 900°F (482°C) for some cracking.

[0037] The hydrogenation feedstock for the hydrotreater can then be further divided or vaporized, and then all fed to the steam cracker. Substantially complete vaporization can occur in the steam cracker system. The combination of separator, flash separator and/or separation tank can be provided between hydrogenation and cracking as required. In a preferred embodiment, the separation process can be integrated with the heating and cracking process, for example with a steam cracker. For example, a vapor-liquid separator or separation process can be provided in the convection section of the steam cracker or between the convection section and the radiant section of the cracker.

[0038] Residual oil hydrotreating preferably includes increasing the hydrogen content of the whole crude oil or crude oil containing residual oil by at least 1% by weight, preferably by 1.5% by weight, and most preferably to achieve that the feed stream from the hydrotreater is close to saturation or Fully saturated. In some embodiments, it may be preferable that the effluent of the hydrotreater has more than 12. A hydrogen content of 5wt%, more preferably more than 13wt%. Increasing the hydrogen content of whole crude oil, crude oil fractions or other feedstocks can be used to make their hydrogenated products suitable for feeding to pyrolysis units for cracking, thereby producing more valuable end products such as olefin billets. As a result, lower cost steam cracker raw materials can be used to produce olefin billets. Suitable lower-value feedstocks may generally include heavy crude oil, those with high residual oil concentration, high sulfur, high TAN, high aromatic billets, and/or low hydrogen content. The hydrogenation of crude oil or crude oil fractions and the removal of contaminants can facilitate the feeding of this effluent to the heaviest components such as asphaltenes and 1100 T + (593 °C +) fractions that can repel the feed stream. Steam cracker system or device. Residual effluent (which includes vaporized residual oil, such as cracked and vaporized 650 T (343°C), up to 1050 T + (565°C), even up to 1100 °F + (593°C +) It can be used for rigorous cracking and production of valuable petrochemical products, such as olefin billets, up to and including some 1400 °F (760Ό) and low boiling points of vaporization). Hope some fouling, and did not produce undesirable tar and coke.

[0039] Surprisingly, the process of this method may not cause uncontrolled fouling of equipment or undesirably produce high yields of tar and residual oil-containing by-products. Also, surprisingly, fully hydrogenated crude oil can be substantially completely vaporized in a steam cracker and result in an increased yield of petrochemical products. Conversion and vaporization can also be aided by steam-assisted flash vaporization. In addition, strict hydrogenation can also greatly reduce the production of steam cracker tar.

[0040] In a preferred embodiment, the hydrotreater effluent selected for steam cracking includes a larger fraction with a boiling point of 700°F (371°C) to 900°F (482°C). In another preferred embodiment, if the hydrotreater effluent contains residual oil, it can be treated first to remove a portion of the residual oil, such as asphaltenes, after which the treated and hydrogenated residual oil-containing material is fed to the heat The convection section or radiant section of the decomposition unit (steam cracker). The preferred method of removing the undesirable residual oil fraction is discussed below.

[0041] Crude oil as used herein refers to the whole crude oil that flows from wellheads, production oilfield facilities, transportation facilities or other initial oilfield processing facilities, optionally including desalination, treatment steps and/or in order to be able to be carried out in oil refineries. Distill the crude oil that needs to be processed in other steps. The crude oil used herein is assumed to contain residual oil, unless otherwise specified. [0042] Crude oil fractions are usually obtained from a tubular steam reactor in an oil refinery. Although any raw material obtained from the refinerys tubular steamer

The oil fraction can be used in the present invention, but the significant advantage provided by the present invention is that the crude oil or crude oil fraction that still contains all or part of the initial residual oil in the whole crude oil obtained from the wellhead can be hydrotreated and subsequently used. Used as raw material for steam cracker. In one embodiment, the crude oil or other feedstock fed to the hydroprocessing unit may include at least 1 wt% residual oil, preferably at least 5 wt% residual oil, more preferably at least 10 wt% residual oil, and still more preferably at least 20 wt% residual oil.

[0043] Residual oil as used herein refers to a compound mixture of heavy petroleum compounds that is otherwise referred to in the art as residual oil or residue. Atmospheric residual oil is the bottom product produced in atmospheric steam when the end point of the heaviest steam product is nominally 650 °F (343Ό), which is called 650 °F + (343°C+) residual oil . Vacuum residual oil is the bottom product obtained from the tower under vacuum when the heaviest distilled product is nominally 1050 °F (565Ό), and is called 1050 °F + (565 °C +) residual oil. (The term "nominal" here means that reasonable experts may have different opinions on the exact points of these terms, but it may not exceed +/-50 °F (or at most +/-100 °F). The 1050 T + (565°C) part contains asphaltenes, which are traditionally regarded as unfavorable factors for steam crackers, leading to corrosion and fouling of the device. The term "residual oil" as used herein refers to 650 °F + (343°C +) residual oil and 1050 °F +(565°C +) residual oil, unless otherwise specified; note that 650 °F +(343°C +) residual oil includes 1050 T +(565°C +) ) Residual oil. According to the present invention, at least a part of 650 T + (343°C) residual oil, up to at least 1050 T + (565°C) ) Boiling point, is vaporized, for example during (i) hydrotreating, (ii) when combined with steam, and/or (iii) between hydrotreating unit and steam cracking, for example during flash separation When the pressure is reduced during the process or when the flash evaporates.

[0044] Residual oil can also generally contain a high proportion of undesirable impurities such as sulfur and nitrogen and high molecular weight (C12+) naphthenic acids (determined by TAN according to ASTM D-664). Another advantage of the present invention is that raw materials containing a large amount of one or more of these impurities can be easily processed. As an example of a specific impurity, a large amount of sulfur may be present in the polycyclic heterocycle. By hydrotreating the residual oil containing these substances, not only the sulfur is removed as &S, but the heterocyclic ring is opened, and a large amount of monocyclic aromatic materials are produced. They are usually valuable commodities themselves and are also preferred steam cracker raw materials.

[0045] The term "hydrotreating" as used herein is defined to include those methods that treat billet raw materials in the presence of hydrogen to hydrogenate or otherwise cause hydrogen to react with at least a portion of the raw materials. This includes, but is not limited to, methods that include the step of heating the residual oil-containing raw material stream in the hydrotreating step in the presence of hydrogen, preferably also under pressure. Hydrotreating can also include, but is not limited to, hydrotreating, hydrotreating, hydrodesulfurization (HDS), hydrodenitrogenation (HDN), hydrodeoxygenation (HDO), hydrorefining, and hydrocracking. method.

[0046] The term "steam cracker" as used herein is also more commonly referred to as a pyrolysis unit or thermal decomposition furnace or pyrolysis furnace. Although steam is optional, it is usually added for one or more reasons, such as reducing the partial pressure of the billet, controlling the residence time and/or minimizing coke formation. In a preferred embodiment, the steam may be superheated, for example in the convection section of a pyrolysis unit, and/or the steam may be acidic or treated process steam.

[0047] Desalination is usually carried out before the raw materials are transported to the tubular steamer. When the residual oil from the tubular steamer is to be hydrotreated, the crude oil feedstock to the refinery is often desalinated twice. Desalination generally removes metal salts such as NaCl. However, desalinated crude oil and crude oil fractions can still contain relatively high concentrations of one or more impurities such as naphthenic acid, sulfur and/or nitrogen. Another advantage of the present invention is that crude oil and crude oil fractions containing one or more of such naphthenic acid, sulfur and/or nitrogen impurities are easy to handle.

[0048] In a preferred embodiment, wherein the raw material includes a relatively large amount of 1050 ° F + (565 ° C +) residual oil, such as 10wt% or more residual oil, or 20wt% or more residual oil crude oil or common The residual oil is compressed, and the raw material containing residual oil can be transported to the convection section of the pyrolysis unit after hydroprocessing, where it is heated. Then, the heated feedstock can be transported to a visbreaker or other vapor-liquid separation device to remove the heaviest components (such as mainly asphaltenes and

1050 °F+(565°C+) points). Preferably, such a device is thermally integrated. Thermal integration provides additional efficiency for the visbreaker or separator.

[0049] In addition to the initial thermal cracking of the residual oil that occurs during hydroprocessing, most of the additional cracking, conversion, and flash separation occur in the visbreaker/separator. This further cracking and conversion is caused by applying an abnormally high separation/visbreaking temperature for an abnormally short contact time, thereby minimizing or controlling the coking to an acceptable level. When the raw material containing residual oil is heated to less than 650 T (343Ό) in the convection section and even up to 700 T at most, and the raw material has a short residence time in the liquid-vapor separation device, thermal cracking rarely occurs to none Occurs, usually only molecules that vaporize under these conditions can be separated, for example, usually non-residual oil components. However, when the feedstock containing residual oil in the convection section according to the present invention is heated above 700°F (371Ό), preferably above 750°F (399°C), still more preferably above 780°F (415Ό) and at When the liquid-vapor separation equipment has a long residence time, a large amount of further thermal cracking of the residual oil will occur. In order to maximize the conversion of residual oil into low boiling point fractions, it is desirable to start cracking residual oil fractions as early as possible in the process. According to the present invention, early thermal cracking is initiated in the hydroprocessing unit, and then in the visbreaking/separation process. The step supports further thermal cracking so as to maximize the part of the vaporized raw material. According to the theory, in The increased concentration of low-boiling fractions produced in the early stages of the process helps or promotes the further fracture, cracking and/or conversion of residual oil into low-boiling fractions. This includes the conversion and cracking of residual oil with a boiling point of up to and above 1100 T + (593°C), and even a part of residual oil with a boiling point of up to 1400 °F (760°C).

[0050] When the effluent of the hydrotreating unit is heated (including reheating) above 780°F (415°C), for example, 780°F (415°F) to 900°F (482°C) and in the visbreaker or During processing in other separators, thermal cracking of residual oil at 650 °F + (343 °C +) still occurred, including those with a boiling point as high as and above 1050 °F + (565 °C). At higher temperatures close to 900°F, the residence time can be shortened to a contact time that is not usually shorter than that of prior art hydrotreating or residual oil hydrofinishing.

[0051] Surprisingly, this occurs in unconverted 1050°F + (565°C) residual oil without the formation of large amounts of coke, scale or solids. This type of thermal cracking and vapor-liquid separation process can be described as "visbreaking". Preferably, separation and heating are integrated methods. The term "integration" as used herein refers to "thermal integration" in that the vapor-liquid separation equipment or visbreaker is connected to the steam cracker through a pipeline, and is adjacent to or relatively close to the steam cracker, so that the raw materials can be It is heated in the convection section of the cracker, fed to the visbreaker, and then the top product of the visbreaker is fed back to the cracker, which has minimal heat loss and preferably does not need to separate the heating related to the visbreaking process .

[0052] Vapor-liquid separation equipment is also referred to as "visbreaker", "separation tank", "separation tank" and "vapor-liquid separator", these terms can be used interchangeably. Also mentioned in this article is the "visbreaker", which is used as a vapor-liquid separation device. The distinguishing feature is that it usually operates at a higher temperature than some other separators, and it is also conducive to further thermal fracture and cracking of the raw materials. The terms "flash tank", "flash tank", "visbreaker", "vapor-liquid separator" and "flash separator" are also well-known terms that generally have similar meanings, and can be used basically interchangeably here. . For example, the separator tank may also be referred to as a visbreaker, or vapor-liquid separator. The term "flashing" generally refers to a phase change from liquid to vapor when at least a part of the material in the container or stream enters by reducing pressure and/or increasing temperature. Therefore, "flash separation" can occur in the "flash tank" due to the inlet of the flash tank or the reduced pressure in the flash tank.

[0053] In a more preferred embodiment, the material is treated by visbreaking or mild thermal cracking to increase the vapor phase ratio by sacrificing bottom products. In some separation methods, such as high-pressure separators and/or flash separators, the raw materials can also be separated into bottom fractions, which are basically liquid fractions, and top fractions, which are basically vapor fractions. . The bottom fraction or liquid phase can include residual oil fractions in it. The vapor fraction can also contain residual oil

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Sub-components. Preferably, the bottom effluent and the vapor effluent each contain components derived from residual oil, although the composition of the residual oil of the bottom effluent is different from that of the vapor effluent. Thus, each of the steam stream and the bottoms stream can be steam cracked.

[0054] Visbreaking is a well-known, non-catalytic, mild thermal cracking method that uses heat to convert or crack heavy hydrocarbon oil and residual oil into lighter components, and sometimes more valuable products, such as cyclones. Alkyl oil, effluent and tar, but the heat will not cause carbonization. The raw material can be heated to the desired temperature under the desired pressure, for example in a furnace or a cracking reaction vessel. The method used may be, for example, a coil type, which is used for high temperature-short residence time, or a cracking reaction method, which is used for low temperature-short residence time processing, to obtain the desired fractured product mixture as required. The billet feed stream can be thermally cracked to reduce the viscosity and chain length of the billet molecules by cracking the molecules in the liquid phase. See, for example, Hydrocarbon Processing, September 1978, page 106. Viscosity cracking occurs when the heavy billet or residual oil is thermally cracked at high temperatures, usually 700°F (371°F) to 900°F (371°F to 482°F) for a few minutes before quenching to stop the reaction. Some residual oil molecules crack or break, producing components that can be removed by standard atmospheric pressure and vacuum distillation. The conversion rate of residual oil in the visbreaker increases with the increase of temperature and residence time. High-intensity visbreaking maximizes the conversion rate of 1050 °F + residual oil by cracking the visbreaker feedstock at a temperature above 840 °F (450Ό) for the longest possible time without forming a large amount of Coke or carbonization.

[0055] One of the key aspects of the present invention is surprisingly using a crude oil stream or fraction containing residual oil that is first rigorously hydrotreated, such as a crude oil that is highly hydrogen-saturated and most of the residual oil has been cracked. Compared with the hydrogen-treated heavy crude oil, the conversion rate of visbreaking higher than previously known can be obtained. The improved visbreaking process and characteristics of the present invention are believed to be attributable to the high hydrogen content of the residual oil portion of the hydrotreater effluent and the increase in light weight content due to the initial cracking carried out in the hydrogenation process .

[0056] In a preferred embodiment of the present invention, particularly severe visbreaking is caused, for example, visbreaking at a temperature exceeding 800 T (427°C) occurs in a vapor-liquid separation plant (visbreaker), Preferably the plant is integrated with the steam cracker (heat integration) as described above. The integrated vapor-liquid separation equipment can discharge the stream every two weeks to remove coke. This enables the separation plant to operate at significantly higher coke yields than a typical visbreaker, which may need to run for several months between shutdowns to remove coke, at least in part due to such system desorption. The complexity and time required for coke. The vapor top product of the visbreaking process (which includes fractions from cracked residual oil) can then be fed to a steam cracker for further cracking into other products including light olefin streams.

[0057] Although light visbroken residual oil molecules (especially residual oil materials with a boiling point of less than 750°F (<400°)) are vaporized without additional treatment, steam stripping is effective for heavy visbroken molecules (such as their boiling point). Vaporization above 750 °F Ο400Ό)) may be necessary and helpful. The visbreaking reaction is fast enough so that purge steam and/or light billets can be added to the vapor-liquid separation equipment to strip the visbroken molecules. This increases the ratio of vaporized billets in the vapor-liquid separation equipment. Heating can also be used to increase the conversion of residual oil.

[0058] Visbreaking can be controlled by changing the residence time of the liquid phase in the vapor-liquid separation equipment. In a preferred embodiment, the liquid phase level can be raised to substantially fill the headspace of the vapor-liquid separation device, thereby increasing the residence time of residual oil molecules to a level sufficient to affect at least partial visbreaking. Preferably, the visbreaker is at least half (50%) full of liquid, more preferably at least 75% full of liquid, and in certain embodiments, most preferably at least 90% full of liquid, based on the total volume of the container. Heating can also accelerate the visbreaking in the liquid phase, and the liquid residue is collected as a bottom stream in the lower part of the vapor-liquid separation equipment. In one embodiment of the present invention, the heater in the lower section of the vapor-liquid separation plant is used in conjunction with the convection section of the steam cracking furnace to provide additional heat if necessary. Attach

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The heat can help keep the residual oil hot enough to continue the reaction and make the residual oil reach a significant visbreaking conversion from 750 °F (399Ό) to 1050 °F (565Ό).

[0059] Preferred vapor-liquid separation equipment or flash tanks and their integration with pyrolysis units were previously described in US Patent Application Publication Nos. 2004/0004022, 20040004027 and 2004/0004028, and were recently filed on February 28, 2005 US application serial numbers 11/06 & 615, 10/851,486 filed on May 21, 2004, 10/851, 546 filed on May 21, 2004, 10/851, 878, 2004 filed on May 21, 2004 10/851,494 filed on May 21, 2004, 10/851,487 filed on May 21, 2004, 10/851,434 filed on May 21, 2004, 10/851,495 filed on May 21, 2004, May 2004 10/851, 730 filed on May 21, 10/851,500 filed on May 21, 2004, 11/134, 148 filed on May 20, 2005, 10/975, 703 filed on October 28, 2004 , 10/891, 795 filed on July 14, 2004, 10/891, 981 filed on July 14, 2004, 10/893 filed on July 16, 2004, 716, 11/009,661 filed on December 10, 2004, 11/177,076 filed on July 8, 2005; and 11/231,490 filed on September 20, 2005. Another preferred device effectively used as the vapor-liquid separation device of the present invention is described in US Patent No. 6,632,351 as a "vapor/liquid separator", such as a visbreaker. Visbreaking is discussed in the aforementioned US Patent Nos. 10/851,486; 11/134,148; 11/009,661.

[0060] In the method of the present invention, the visbreaker or vapor-liquid separation equipment is preferably at 700°F (371°C) to 900°F (482°C), more preferably 750°F (399°C) to 900 °F (482 °C), still more preferably 780 °F (415 °C) to 900 °F (482 °C) and most preferably 800 °F (427 °C) to 875 °F (468 °C) temperature Next operation. Let the hydrotreated and partially cracked residual oil-containing material pass through a vapor-liquid separation drum while undergoing some pressure drop to obtain top vapor and bottom liquid, which can also be referred to as "flashing" (or other changes). Body, depending on the context).

[0061] Another aspect of the present invention relates to the API gravity and sulfur content of the steam cracker feedstock. It is known that the quality of steam cracker feedstock improves as the API specific gravity of the feedstock increases and the sulfur content decreases. The inventors surprisingly discovered that the raw materials rich in sulfur and rich in high-boiling polynuclear naphthenic billets, polynuclear aromatic billets and partially saturated polynuclear aromatic billets (which tend to have lower API gravity), when first hydrotreated It can be the preferred feedstock for steam crackers.

[0062] It is also well known in the art that the specific gravity and sulfur content of crude oil increase with increasing boiling point. For this reason, feedstocks rich in vacuum residues from crude oil with 15-40 API specific gravity and 1-4 wt% sulfur may be some preferred feedstocks for the method of the present invention. Residual oil hydroprocessing removes sulfur throughout the boiling range of the feedstock. A large amount of hydrogen is consumed to remove heteroatoms from the vacuum residue and saturate the polynuclear aromatics contained in the vacuum residue. Residual oil hydrotreating can be accompanied by catalytic cracking and thermal cracking of residual oil molecules into components that can be separated by standard analysis methods. Initially, the inventors searched for residual oil hydrotreating conditions that can achieve higher than 50% 1050 T + conversion and higher than 90% desulfurization. The inventor surprisingly invented a method in which the 1050 T+ conversion in the residual oil hydrofiner (residual oil hydrotreater) is unnecessary, because this function can be passed in a separate step This is achieved by visbreaking the effluent of the residual oil hydrofiner.

[0063] Residual oil hydroprocessing is used in other refining methods to pretreat atmospheric residual oil (which contains 25-35wt% vacuum residual oil) in order to be used as a raw material for FCC units. In this method, the coke yield of the hydrotreated residual oil is usually 5-8wt%. This means that 92-95% of the residual oil feedstock fed to the integrated residual oil hydrorefiner and FCC unit is converted into liquid and gas stock products, and only 5-8wt% is lost as low-value coke.

[0064] The inventors surprisingly found that by integrating residual oil hydrotreatment, visbreaking and steam cracking to produce olefin billets, similar results can be obtained. In the method of the present invention, the hydrotreated residual oil is visbroken, and the vaporized top product from the visbreaker is steam cracked. The inventors surprisingly found that this method produces 6-9wt% visbreaker crack

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The bottom product of the carburetor (similar to the coke produced in the FCC but higher value) and 91-94wt% steam cracker product. [0065] In order to make full use of the visbreaking ability of the method of the present invention, the preferred raw material in the embodiment may contain

20-50wt% vacuum residual oil, some raw materials can even be whole crude oil. Residual oil hydroprocessing consumes a lot of hydrogen. The inventor noticed that hydrogen will be introduced into the vacuum residue feedstock to produce a hydroprocessing effluent material that can only be used as fuel oil, the value of which is lower than the value of the required chemicals (such as light olefin billets). As mentioned above, one purpose of the method of the present invention is to increase the hydrogen content of the steam cracker feedstock while minimizing the increase in the hydrogen content of the remaining residual oil, which is usually sold as low-value fuel oil. The integration of rigorous hydroprocessing and visbreaking has surprisingly achieved this goal. Viscosity cracking effectively removes side chains with high hydrogen content from the core composed of polynuclear cycloalkanes and aromatic billets. The fouling in the visbreaker is limited by limiting the temperature and controlling the residence time, thereby avoiding the over-formation of coke or fouling of equipment.

[0066] Crude oil or its residual oil content, especially atmospheric residual oil, vacuum residual oil, or any refinery or chemical intermediate stream containing residual oil or asphaltenes can also be used in the hydrotreating process of the present invention. Raw materials are preferred. When the feedstock contains more than 0.1 wt% or preferably more than 5.0 wt% asphaltenes, it is advantageous to use vapor-liquid separation equipment to remove the asphaltenes before entering the radiant section of the pyrolysis unit. Preferably, as described above, the vapor-liquid separation device (visbreaker) can be advantageously thermally integrated with the pyrolysis unit, so that the feedstock is preheated in the convection section of the pyrolysis unit before entering the vapor-liquid separation device. Therefore, the term "integrated vapor-liquid separation device" is as used herein. As an alternative, the vapor-liquid separation equipment can basically not be thermally integrated with the cracker, so that the visbreaker has its own independent or supplementary heat source, so that the asphaltene and any unsaturated or uncracked residual oil enter the pyrolysis unit in the feedstock. The radiation section was removed before. Both integrated and non-integrated configurations are within the scope of the present invention.

[0067] Preferred feedstocks may include raw material streams with high concentrations of tar and crude oil fractions such as topped crude oil ("topped crude oil" is approximately 500-600 T (260-315Ό) fraction and higher fraction) . Generally, topping crude oil is used synonymously with atmospheric residual oil. Then, any crude oil or crude oil containing residual oil can be advantageously processed according to the method of the present invention to obtain chemical products (light alkene and/or monocyclic aromatic crude), regardless of the residual oil content therein.

[0068] The following embodiments are used to illustrate but not to limit the present invention. Many modifications and variations are possible, and it should be understood that within the scope of the appended claims, the implementation of the present invention may be different from what is specifically described herein.

[0069] In the following drawings, "HDP" is a hydrotreating unit, "HPS" is a high-pressure separation device (for example, a tank with level control that separates gas and liquid under pressure), and "steam cracker" is The pyrolysis unit, as well as the "steam cracker product recovery" is a system that includes one or usually several separation steps, such as a steam tower. All of these devices or systems alone can be basically ordinary devices, and are known in the art respectively.

[0070] With reference to the exemplary drawings, FIG. 1 is a process flow diagram illustrating an embodiment of the present invention, in which a raw material 8 containing residual oil is hydrotreated in a hydrotreating unit 10, and then sent to a steam cracker 20 for A number of products 41-44 were obtained, including the olefin blank 42. The design details of the steam cracker 20 itself are not the subject of the present invention. Processing conditions can usually be easily determined by those skilled in the art. Unconventional steam cracking designs known in the art, such as furnaces heated by directly mixing superheated solids or gases with liquid feedstock containing residual oil, are also considered by the inventors for the invention described herein.

[0071] An embodiment of the method of the present invention for preparing a residual oil-containing feedstock for steam cracking includes by heating the feedstock at temperatures above 700°F (371°C), preferably above 750°F (399°C), and more It is preferable to hydrotreat the raw material strictly at a temperature exceeding 780°F (415°F). The method also includes further improving the hydrotreater effluent by maintaining, heating, and further converting the hydrotreater effluent in a visbreaker-type vapor-liquid separator. Preferably, the visbreaker is thermally integrated with the steam cracker. In the heat integration method shown in Figure 1, the atmospheric residual oil 8 is sent to the ordinary hydrogenation

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Processor (HDP) 10, such as a fixed bed hydrotreating processor. Many HDP units are commercially available, especially depending on the catalyst and configuration. For example, they can be ordered from ExxonMob. The design details of the HDP itself are not the subject of the present invention. The processing conditions of HDP are usually easily determined by those skilled in the art. The recovery of petrochemical products (light olefin billet and aromatic billet) is largely affected by the processing conditions selected in the HDP 10, the visbreaker-type vapor-liquid separator 30, and the steam cracker 20.

[0072] The hydrogenation feedstock 14 of the HDP unit is then sent to one or more separation devices (not shown) to recover hydrogen, lower the pressure and lower the temperature. A stream including hydrogen and light carbon products such as C2 and below can be recycled 12, and a hydrogenated effluent stream 14 containing products with a C2 boiling range (C2+) and higher (for example, up to 1500 T) is recovered for further processing. Note that in many cases, the recycled stream 12 can contain H₂S, it is preferably removed before entering the HDP unit 10, for example through membranes, absorbents, etc. The bottom stream of HPS (not shown) can be divided into two or more streams. In addition to being used in the method of the present invention, this bottoms stream (not shown) can be recycled to the residual oil hydrotreater 10, or further processed by conventional steaming and refining.

[0073] In the case where the feedstock 14 still contains asphaltenes, they can advantageously be removed before entering the radiant section 24 of the steam cracker 20. The above and the following examples more fully discuss examples of methods for removing asphaltenes. Although not shown in detail in FIG. 1, the hydrogenated C2+ stream 14 can be preheated in the convection section 22 of the steam cracker 20 before entering the vapor-liquid separation device 30, which contains (marked) asphaltenes that have not been removed in advance. It is said that 1050 T + residual oil can be removed from the vapor-liquid separation device 30 as a bottom product 32. The vapor 34 returns to the convection section 22, preferably without cooling or condensation. The device schematically referred to as "S/C furnace" 20 in FIG. 1 is a common example of a steam cracking furnace, and its details are not the subject of the present invention. In addition to the integration of the vapor-liquid separation device 30, it has been described elsewhere in this document. It is described in the references discussed. The separation device 30 preferably functions as a visbreaker in that the device 30 separates, temporarily maintains and further heats the stream previously heated in the hydrotreater. As a result, initial cracking is caused in the hydrotreater, producing some light weight fractions, and then causing subsequent cracking in the visbreaker. Through the light points generated in the hydrogenation processor, Additional light molecules produced by the visbreaking process are further injected into the visbreaker and/or steam injected before the visbreaker, and optionally through the flash pressure drop, substantially complete vaporization can be achieved. The separator 30 is also preferably thermally integrated with the cracker 20 in that the separator is close enough to the steam cracker 20 so that the separator preferably does not require additional or separate heating to facilitate the separation of visbreakers in the separator 30. Thus, the separator 30 can be "integrated" with the steam cracker 20. The pressure is preferably reduced to 50-100 psig before sending the separated stream to the steam cracker.

[0074] Although not shown in detail in FIG. 1, in a preferred embodiment, the hydrogenated C2+ stream 14 passes in the convection section 22 of the steam cracker 20 at a temperature sufficient to initiate thermal cracking of the hydrogenated residual oil. The pipeline 33 is heated before being transported to the vapor-liquid separation device, and the (nominal) 1050°F + residual oil containing asphaltenes is removed from the vapor-liquid separation device 30 as a bottom product 32. Steam (not shown) may be added to the vapor-liquid separation device to increase the ratio of the raw material removed as vapor 34. Another aspect of the present invention is that for a given treatment temperature (especially high boiling point residual oil), increasing the liquid level in the visbreaker separator can increase the liquid residence time, thereby further improving the conversion rate of residual oil. The visbreaker includes a vapor-liquid separation vessel or device that separates liquid fraction from vapor fraction, wherein the separation vessel includes a liquid volume that preferably occupies at least 50% of the volume of the vessel. Preferably, the liquid level of the separation container is at least equal to or higher than 75% by volume of the container, still more preferably higher than 80% by volume, and most preferably higher than 90% of the volume of the container.

[0075] The vapor 34 (which includes residual oil molecules that have been thermally cracked (also known as destructive steam)) can be returned to the convection section 22. In this way, the convection section 22 of the steam cracker 20 can convert 1050 T + vacuum residual oil into light molecules. Eventually, the output of fuel oil decreased, and the output of petrochemical products (such as the required light olefin billet and single-ring aromatic billet) increased. If the temperature is too high or the residence time of the feedstock is too long, the thermal visbreaker vapor-liquid separation device 30 can cause coke formation. Such as

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If this happens, the method may undesirably fill the vapor-liquid separation device 30 with coke, which requires the method to be interrupted. In a preferred embodiment, the temperature and residence time in the vapor-liquid separation device 30 are controlled to allow only a small amount of coking. For example, the steam cracker may be shut down every 15-40 days to easily remove an acceptable amount of coke from the radiant section 24, piping, and/or separator 30 of the furnace 20 if necessary. The method of the present invention can adopt known methods and facilities to remove coke from the pipes of the vapor-liquid separation device 30 and the convection section 22 and the radiant section 24 of the steam cracking furnace 20. Because of this synergistic effect between visbreaking and steam cracking, the method of the present invention can reduce the residual oil in the visbreaker feedstock at a higher stringency than the ordinary visbreaker. The conventional visbreaker is designed It runs for several months before decoking is required.

[0076] The device schematically represented as "S/C furnace" 20 in FIG. 1 is a common example of a steam cracking furnace. In addition to the integration of vapor-liquid separation equipment (not shown in FIG. 1), its details are not the present invention. The subject of this article has been described in references mentioned elsewhere in this article.

[0077] In another embodiment, all or any fraction of the hydrotreater effluent 14 containing 1050°F + (565°C +) residual oil may be heated in the steam cracker 20 or by a separate heat source The temperature is high enough to initiate thermal cracking, but not to cause significant coking. The cracked stream can be kept at this temperature for a long enough time to obtain a conversion rate of 5wt% (low stringency) to 60wt% (high stringency) of 1050 T+ residual oil (that is, the material changes from 1050 °F (565 °C) ) The high-boiling-point residual oil of the residual oil is converted into low-boiling-point materials) but is short enough not to cause significant coking. The optimal temperature and time ("time at a certain temperature") for each specific raw material are different and can be determined by those skilled in the art through routine experiments. The time at a certain temperature is selectively terminated by quenching the hot bottom material to avoid fouling or coking. Based on the present disclosure, those skilled in the art generally consider this to be visbreaking. In the visbreaking vapor-liquid separation step, the (nominal) unbroken 1050 T + residual oil and/or asphaltenes are removed as bottom products from the vapor-liquid separation equipment, and all or part of the visbreaker The vapor effluent 34 is sent to the steam cracker 20 before entering the radiant section 24, preferably to the convection section 22. The separated vapor is further processed in the radiant section 24 And cracking, thereby obtaining a steam cracker effluent 26 containing the desired light olefin billet 42.

[0078] An important advantage provided by the present invention is the high stringency hydrotreating and visbreaking of the effluent 14 of the hydrotreater, whether it is a visbreaker that is configured before the steam cracker and has an additional or separate heat source Among them, the visbreaker integrated with the steam cracker can achieve high conversion rates, such as hydrogen-rich 750 °F + (399 °C +) residual oil and even 1050 °F + (565 °C +) materials Most of it is at least 50wt%, or even higher than 50wt%, for example up to 55wt% and even up to 60wt%. This provides a steam cracker feedstock 34 (or feedstock to the radiant section 24, if the visbreaker is integrated with the convection section 22 of the steam cracker) with more than 13wt% hydrogen. The bottom product 32 of the visbreaking plant 30 may include less than 11.5% by weight hydrogen in certain embodiments, and may be used as fuel oil and/or recycled to the hydrotreater, or fed to another processing unit such as Catalytic conversion system.

[0079] In the embodiment schematically illustrated in FIG. 6, the method of the present invention integrates the steps of residual oil hydrotreating 10, hydrotreated residual oil visbreaking 30, and steam cracking 20. A conventional visbreaker can be operated to implement the operating parameters of the present invention, thereby separating the vapor and/or liquid that has been discharged from the unconverted residual oil feedstock. The effluent liquid and/or vapor obtained from the residual oil hydrotreater 10 and/or the visbreaker 30 are processed in the steam cracker 20 to produce petrochemical products. At least one obvious advantage of this embodiment is that there is no need to directly integrate the vapor-liquid separation equipment with the convection section of the steam cracker 20.

[0080] The product of the steam cracker 20 is sent to the steam cracker product recovery section (not shown in FIG. 6), where various products can be recovered through separation, usually through steam. The "chemical" stream includes ethylene, propylene and butenes. Separate

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It is a conventional technique in itself and is not the subject of the present invention.

[0081] Certain variations are obvious to those skilled in the art. For example, one or more vapor-liquid separation devices can be exchanged with other separation devices such as membranes, and integration with a steam cracker, although a preferred embodiment, is optional. However, it is highly preferred to remove the asphaltenes before the radiant section of the pyrolysis unit (steam cracker). Membranes are particularly useful, for example, to separate polar substances from non-polar substances (for example, before HDP units).

[0082] In the embodiment shown in FIG. 6, the method of the present invention integrates the steps of residual oil hydrotreating 10, hydrotreated residual oil visbreaking 30, and steam cracking 20, and can operate conventional visbreaking To separate out the vapor and/or liquid from unconverted residual oil raw materials. The liquid and/or vapor obtained from the residual oil hydrotreater and/or visbreaker is processed in a conventional steam cracker to form petrochemical products. At least one important advantage of this embodiment is that there is no need to directly integrate the vapor-liquid separation equipment with the convection section of the steam cracker.

[0083] FIG. 2 is a process flow diagram illustrating an embodiment of the present invention, in which the raw material 8 containing residual oil is hydrotreated

10 and 14 are then sent to the steam cracker 20 to obtain various products including olefin billets.

[0084] In the embodiment of the method shown in FIG. 2, the feedstock 8 (which in the preferred embodiment is atmospheric residual oil) is transported to a conventional hydrotreating unit (HDP) 10, such as a fixed bed hydrotreating unit. Again, the design details of the HDP itself are not the subject of the present invention. Exemplary process conditions for HDP step 10 are provided in FIG. 2. However, as recognized by those skilled in the art, these conditions can be changed and can be determined by routine experimentation. The actual conditions of one or more HDP units vary according to the specific feedstock and/or desired product integration with steam cracker conditions and visbreaker conditions, but a good starting point would be 2200 ± 500 psig (total pressure), 725 + 100 °F (measured at the reactor outlet), 3000 + 200SCFB hydrogen treated at 0.1-0. 3WHSV.

[0085] The hydroprocessing feedstock 14 is sent to a high-pressure separator 15 operating under the conditions specified in, for example, FIG. 2. The conditions can also be changed and determined by a person skilled in the art through routine experiments, depending on the feedstock and the system shown. The operating conditions of other devices in the The top stream 16 passes through a heat exchanger 17 shown in a conventional manner with an arrow passing through a circle, and may be composed of a so-called product having a boiling point of, for example, 650°F or lower. The cooled top stream 18 can be transported to the first HPS19 shown in FIG. 2, and the stream is separated at 90 T as shown to obtain materials containing C3 and higher carbon number materials (including naphtha and heavy hydrocarbons). Effluent) bottom stream 21 (which can be sent to the steam cracker 20) and top stream 23 containing hydrogen, methane, ethane and the top stream 23, the top stream is recycled, preferably after removal of H by membranes, absorbents, etc.₂After S.

[0086] In the exemplary embodiment shown and illustrated in FIG. 2, the bottoms stream 35 obtained from the first HPS 15 may include materials having a boiling point above 650°F. In some embodiments, the bottoms stream 35 may be recycled or mixed with the bottoms stream 21 of the second HPS 19 and then depressurized 55. In fact, usually a part (for example, 0-90wt% or 40-60wt%) is recycled (not shown), and a part of 35 (for example, 10-100wt% or 40-60wt%) is mixed and depressurized. Mixing with the 90°F liquid cools the liquid 35 from the first HPS15, reducing the amount of flashing that occurs during decompression.

[0087] In another embodiment, the combined liquid effluent 14 from the residual oil hydrotreater 10 containing residual oil and, for example, vacuum gas oil (VGO), may be preheated in the convection section of the steam cracker 20, The vapor from the integrated vapor-liquid separation plant is then returned to the convection section, and then introduced or transported to the radiant section of the steam cracker, where it is cracked. The bottom stream from the integrated vapor-liquid separation plant consisting of 1050°F + fraction (in the preferred embodiment) includes asphaltenes.

[0088] The product 26 of the steam cracker 20 can be transported to the steam cracker product recovery section 40, where various products 41-44 can be recovered through separation, usually through steam, as shown in FIG. 2. The "chemical" stream 42 includes, for example, ethylene, propylene, and butenes. Each steam cracker 20 can be integrated with its own product recovery device 40, or a single product recovery device

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The collection unit 40 can process two steam cracker effluents 26.38.

[0089] Certain variations will be apparent to those skilled in the art. For example, other separation equipment such as membranes or vacuum towers can be added. The membrane is particularly useful for separating polar and non-polar substances (for example before the HDP unit) or separating aromatic and non-aromatic materials (for example, after the second HPS unit in Figure 2 and before the steam cracker). , Transport the non-aromatic billets to the steam cracker and recycle the aromatic billets to the hydroprocessing unit).

[0090] FIG. 3 shows another preferred embodiment of the present invention. Fig. 3 is similar to Fig. 2, except that in Fig. 3, the tar 44 from the product recovery unit 40 heated to 100-200°C to maintain fluidity, is now substantially free of metals and contains very little sulfur, can be transported to the HDP 10, preferably Dilute with one or more 650°F + recycle streams 23 and/or raw materials 8, or a portion of one or both of these materials.

[0091] FIG. 4 shows another embodiment of the present invention. Fig. 4 is similar to Fig. 3, except that the second HDP unit 70, the second heat exchanger 72 and the third HPS unit 74 are provided. As shown in FIG. 4, the material 76 (for example, 400-650°F (204-343Ό) liquid) from the third HPS unit 74 is sent to the second HDP unit 70 as a raw material. The tar 44 is optionally recycled to the second HDP unit 70. Fig. 4 further uses a vapor-liquid separation device 25 (flash in Fig. 4) in order to separate the 900 Τ-vapor 36 from the 900 Τ + residual oil 37. The 900 Τ-steam 36 (mixed with steam 31) can be directly transported to the conventional steam cracker 20 without the need for integrated vapor-liquid separation equipment. The 900 T + residual oil 37 can be delivered to the steam cracker 50 including the integrated vapor-liquid separation unit 30 to be visbroken. The vapor-liquid separation device 30 can be operated under various conditions, which can be easily understood by those skilled in the art. In another variation (not shown), a part of the tar 44 may be mixed with the atmospheric residual oil 8 and a part with the bottom product 76 of the third HPS unit.

[0092] Based on this disclosure, those of ordinary skill in the art will recognize that in any of the above-mentioned FIGS. 1-4, a visbreaker may be arranged before one or more steam crackers. If the visbreaking step precedes the pyrolysis step, according to the present invention, a vapor-liquid separation device integrated with the pyrolysis furnace will be optional. This can be explained with reference to the following embodiments and other drawings described below.

[0093] Referring to FIG. 5, visbreaking is completed in a vapor-liquid separation device 30 integrated with the steam cracker 20. In the example shown in Figure 5, crude oil is steamed at 1 atmosphere pressure until the remaining oil reaches 600°F (approximately 315°F). Heavy oil (residual oil) is analyzed (see Table 1). The heavy oil (residual oil) is mixed with hydrogen and processed through the hydrotreating processor 10 at 0.2 WHSV. 695 T and a total pressure of 2000 psig. Analyze the hydrotreater effluent 14 (see Table 1). The liquid product 14 of the hydrotreater is then vacuum distilled (not shown in Figure 5) to separate the vacuum residue. Steamed to obtain 82wt% of the extract (1050-) and 18wt% of the vacuum residual oil (1050+). The analysis results are provided in Table 1.

[0094] The result of visbreaking 30 of 18wt% vacuum residual oil can be estimated. Due to the high hydrogen content (12.5 wt%) of the feedstock 14, a high conversion rate in the visbreaker 30 is possible before a large amount of coke begins to form. Strict visbreaking produces a vacuum residue containing up to 10.8wt% hydrogen in a 40% yield and a top product with a hydrogen content of 13.5wt% Η in a 60wt% yield. The calculated hydrogen (H) content of the top product of the visbreaker is close to the H content of the residual oil hydrofining liquid. Therefore, it can be assumed that adding the top product of the visbreaker to the hydrotreating liquid will not significantly change the steam cracking yield. The 93 wt% waste material stream 34 from the residual oil hydroprocessing step can then be used as a steam cracker feedstock. Table 2 provides the yield of steam cracking, which is basically the same as the yield shown in Figure 5. The experiments reported in these examples simulate industrial-scale operations, as shown in Figure 5 and described throughout.

[0095] Table 1

[0096]

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<td></td><td>Crude Oil Atmospheric Residual Oil</td><td>Hydrotreater effluent</td><td>1050-</td><td>1050+</td>

<td>API weight</td><td>17. 8</td><td>27. 0</td><td>30.0</td><td>17. 5</td>

<td>Wt% Η</td><td>11. 3</td><td>12. 9</td><td>13. 1</td><td>12. 5</td>

<td>Wt% S</td><td>4. 2</td><td>0. 15</td><td>0. 01</td><td>0. 3</td>

<td>Wt% C5-</td><td>0. 0</td><td>3. 0</td><td>5. 0</td><td>0. 0</td>

<td>Wt% C5-1050 °F</td><td>64. 0</td><td>80. 0</td><td>95. 0</td><td>0. 0</td>

<td>Wt% 1050+</td><td>36. 0</td><td>18. 0</td><td>0. 0</td><td>100. 0</td>

<td>Alkane billet</td><td>16. 0</td><td></td><td>27. 0</td><td></td>

<td>Naphthenic billets</td><td>19. 0</td><td></td><td>39. 0</td><td></td>

<td>Single ring aromatic billet</td><td>8.0</td><td></td><td>26. 0</td><td></td>

<td>Bicyclic aromatic billet</td><td>15. 0</td><td></td><td>7. 0</td><td></td>

<td>Three-ring aromatic billet</td><td>17. 0</td><td></td><td>2. 0</td><td></td>

<td>Four ring Fang billet</td><td>13.0</td><td></td><td>0. 0</td><td></td>

[0097] Table 2-Steam Cracking Yield: Hydrotreater 1050-Liquid

[0098]

<td></td><td>Steam cracker yield, wt%</td>

<td>Fuel gas</td><td>10</td>

<td>Ethane/Propane</td><td>5</td>

<td>Ethylene</td><td>21</td>

<td>Acrylic</td><td>13</td>

<td>C4' s</td><td>10</td>

<td>BTX</td><td>9</td>

<td>Other SCN</td><td>11</td>

<td>Tar and gas oil</td><td>21</td>

[0099] The results in Table 1 show that the feedstock for the residual oil hydrotreating step contains 36wt% boiling point at 1050°F

The above materials. The product of the hydrotreating step contains 18% by weight of materials with boiling points above 1050°F. Conventional hydroprocessing results in a 50% conversion rate of the vacuum residue of the feedstock. This means that the hydrotreating and subsequent vacuum distillation yielded a product with 18wt% vacuum residual oil and close to 80wt% liquid suitable for use as a steam cracker feedstock. 18wt% vacuum residual oil is mainly rich in hydrogen, but can only be sold as low-sulfur fuel oil unless it is further processed. It is hoped to reduce the yield of low-sulfur fuel oil and increase the yield of steam cracker feedstock. The visbreaking step converts approximately 60% by weight of 12.5% Η, 1050°F + hydrotreater effluent into steam cracker feedstock. The unconverted 1050 °F + residual oil hydrofining effluent contains 10. 8wt% H, which is similar to the H content of the feedstock fed to the residual oil hydrotreater (11. 3wt%). The combination of residual oil hydrotreating and visbreaking results in an 80% overall conversion rate for the vacuum residual oil portion of the feedstock fed to the hydrotreater. The 7wt% low-sulfur fuel oil ("residual oil" in Figure 5) has a hydrogen content similar to that of the residual oil hydrotreater raw material, so there is almost no hydrogen consumption in the residual oil hydrotreater, and it is sold to consumers as fuel oil By. On the contrary, the residual oil hydrotreating of the raw material can make the visbreaking process proceed with an unusually high conversion rate. Feeding the rigorously hydrotreated residual oil to the visbreaker is also believed to be an important advantage of the embodiment of the present invention that has not been previously recognized in the art, because it is completely unclear why it can be used for visbreaking according to the present invention The raw material is the opposite of feeding the raw material to the coker or FCC unit in the prior art.

[0100] Residual oil hydroprocessing using similar raw materials and conditions as those listed in the above table is used to pretreat the residual oil used as the feedstock of the FCC unit. In the FCC unit, the hydrotreated residual oil can be converted into liquid and gas products with a coke yield of 5-6 wt%. It is very surprising that residual oil hydrotreatment and subsequent visbreaking and steam cracking have achieved similar total residual oil conversion rates for liquid and gas products. The by-product of residual oil hydroprocessing, visbreaking and steam cracking is low-sulfur fuel oil ("residual oil" in Figure 5), which has a significantly higher value than coke on FCC catalysts.

[0101] The two key parameters of the steam cracker feedstock are wt% hydrogen and wt% polynuclear aromatics. The ethylene yield can be closely related to Wt% hydrogen, and the tar yield can be closely related to wt% polynuclear aromatics. The product obtained by hydrotreating the residual oil of FIG. 6 has the typical hydrogen content of the ordinary VGO used in the field of steam cracking, but has a lower polynuclear aromatics concentration.

[0102] The result of a steam cracked feedstock with &gt;20wt% aromatic billet is a tar yield of 10-20wt%. The method of the present invention provides an opportunity to eliminate or greatly reduce the tar as a product by recycling the tar to the hydrotreater. Tar hydrogenation and subsequent steam cracking can substantially completely convert tar into light products. This is an ideal of the method of the present invention, but not just a necessary aspect. The steam cracker tar is abnormally hydrotreated in advance. It is expected to have problems with fouling, incompatibility and low reactivity.

[0103] Although the above embodiments use atmospheric residual oil as a raw material for illustration, any crude oil or its fraction can benefit from the present invention. In a preferred embodiment, the feedstock is selected from heavy crude oil, vacuum residual oil, fuel oil, FCC cycle oil, coker gas oil, cracker tar, topped crude oil, and any other residual oil-containing and/or high-concentration polycyclic aromatic oil. At least one of the raw materials of the blank material. Mixtures of such raw materials, such as those provided by crude oil, are also preferred. Figures 1-6 show only a few of the countless possible optimizations that involve minimizing the energy use of the refinery and maximizing the efficient use of hydrogen and raw material sources.

[0104] As an additional non-limiting example illustrating yet another embodiment (which may be a more preferred embodiment), the hydrogen source used in the system (such as the HDP unit) may come from a source of methane, especially remote methane. The use of remote methane as a hydrogen source is described in US Patent No. 6,784,329.

[0105] Maximizing the value of remote methane resources is an old problem in industry. Although methane has excellent value for hydrogen production, it is generally not economical to transport any chemicals over long distances. Hydrogenating the feedstock of the hydrotreating unit using methane from remote areas or other sources of high capacity and/or underutilized capacity of methane may be beneficial to economically improve the production of valuable products from steam cracking. The wording "distant" is not limited to distance, but is more broadly defined as

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Including basically any suitable source of methane and/or hydrogen, they may be only a less valuable option in the process or have little chance of being used in the process. This includes methane produced in large quantities around the world, which may be restricted, costly or unsuitable in terms of market access or restricted use. This methane can be converted to hydrogen used in the process of the invention.

[0106] Crude oil usually contains a minimum of 10 wt% hydrogen. Fully hydrogenated crude oil (where the crude oil basically contains only paraffin billets and naphthenic billets, with a conversion rate of &gt;95wt% of impurities containing sulfur, nitrogen and oxygen) can contain as much as 14-15wt% hydrogen. The saturated cracker feedstock is a highly preferred feedstock in the present invention. The yield of petrochemical products of crude oil with 14.5wt% hydrogen can be significantly increased compared to crude oil with 10-11wt% hydrogen.

[0107] A convenient way to convert methane to hydrogen in remote locations is to use a steam reforming unit, which is available from many commercial sources. In steam reforming, light billets such as methane react with steam to form hydrogen and carbon monoxide. This reaction can be explained by the well-known syngas balance equation:

[0108] CH4+H2O"all3H₂+C0

[0109] Generally, synthesis gas is utilized, for example, by converting it into a lower alkane billet with a Fischer-Tropsch catalyst, which can be fed to a naphtha cracker to produce ethylene. However, according to the present invention, hydrogen can be extracted from the product side of the equation and used to hydrogenate crude oil or its residual oil content. Carbon monoxide can further react with steam in the water gas shift reaction to form additional hydrogen (and carbon dioxide). Other reactions can produce hydrogen from methane, for example methane reacts with oxygen to form hydrogen and carbon monoxide (partial oxidation).

[0110] The present invention therefore allows manufacturers to place the hydroprocessing HDP unit close to the methane source (for example, remote methane), hydrogenate the feedstock containing residual oil (for example, from a wellhead located near the remote methane or by distributing residual oil-containing methane). The material is transported to a remote methane location), and then the product of the HDP unit is shipped to the steam cracker (or the steam cracker is located at a remote source).

[0111] In addition to those noted above, the present invention provides many advantages. In a preferred embodiment, the present invention provides one or more of the following advantages: (a) Use of the lowest cost raw materials (1050 T + residual oil of the raw materials and/or high content of polynuclear aromatics and/or heteroatoms; use of remote locationsofmethane); (b) When combining the conversion in the residual oil hydrofiner and the visbreaker, it has a high total conversion rate of 1050 °F +; (c) Raw materials including hydrogen and steam cracking The low-cost integration of reactor facilities basically has no transportation costs; (d) a single feed simplifies the design and/or maintenance of the pyrolysis unit; (e) reduces residual oil/asphaltene/sulfur and nitrogen polynuclear molecules ("oil barrels"). (F) It provides an alternative to naphtha reforming for the production of Fangbi products.

[0112] Although the present invention has been generally described with reference to specific embodiments, in a preferred embodiment, the present invention relates to a method comprising the following steps: (i) acquisition under relatively stringent conditions, for example, preferably more than 700 °F (371 °C), more preferably a feedstock containing the effluent from the residual oil hydrotreating unit processed at a temperature exceeding 750 °F (399Ό); (ii) separating the effluent in a separator (for example, visbreaking) It is a top stream and a bottom stream, where the top stream includes steam; then (iii) the top stream of the visbreaker is transported to the radiant section of the steam cracker; (iv) the effluent containing the olefin billet is obtained from the steam cracker.

[0113] This can be improved or enhanced by one or more of the following still more preferred embodiments: wherein step (iii) is characterized by transporting the top stream of the visbreaker to the steam cracker as steam without cooling or condensation; Step (iii) includes transporting the top stream of the visbreaker to the convection section of the steam cracker, and then to the radiant section of the steam cracker; step (ii) includes transporting the effluent to the convection section of the steam cracker, and then The effluent is visbroken in the vapor-liquid separation device; in step (ii), the visbreaker/vapor-liquid separation device is thermally integrated with the steam cracker; step (i) is further characterized by the inclusion of crude oil or crude oil Hydrotreating of raw materials to obtain the original

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Oil or hydrotreated crude oil fraction, wherein the hydrotreated crude oil fraction includes residual oil; step (i) is further characterized in that it will contain &gt;20wt% or &gt;25wt%, or &gt;30wt% 1050°F + residual oil And&gt; 20wt% or&gt; 25wt% or&gt; 30wt% aromatic billet and &lt;25wt% or &lt;20wt% or &lt;15wt% paraffin billet crude oil or raw material hydrotreating to obtain hydrotreated crude oil or Hydrotreated crude oil fractions, where hydrotreated crude oil fractions include residual oil; visbreaking is carried out under suitable conditions (usually 700 °F (371Ό) to IJ900T (482 °C), or higher in other embodiments At 850 °F (&gt;450Ό) to 900 °F (482°C), or within the preferred operating range of 425-467Ό vapor-liquid separation equipment, or any lower limit to any upper limit given in the bracket expression Within the range, such as 425-482°C and 450-467°C) to provide more than 5wt%, preferably 5-60wt%, more preferably 50-60wt%, still more preferably &gt;50wt% to 60wt%, still more preferably&gt; 55wt% to 60wt%&gt; 1050 °F + residual oil to &lt;1050 °F + conversion rate of the material (in other words In other words, the "time at a certain temperature" sufficient to provide the above conversion rate); including the step of visbreaking the hydrotreated crude oil or hydrotreated crude oil and the subsequent acquisition of residual oil content and The step of separating the residual oil-free fraction, and then steam cracking the residual oil-free fraction into a product containing olefin billet; the raw material includes crude oil or crude oil fraction containing at least one impurity, and the impurities are selected from : (A) based on the weight of the raw material, more than 1wt%, more preferably more than 3wt% of sulfur, (b) based on the weight of the raw material, more than 10wt%, preferably more than 20wt%, more preferably more than 30wt% residual Oil, (c) TAN measured by ASTM D-664 is 2 1.0, preferably 2 1.5, more preferably 2 2.0, still more preferably 3 2.5 mg KOH/g oil, still more preferably 2 3.0 mg KOH/g oil Naphthenic acid; step (i) saturate at least 20 wt%, preferably at least 40 wt%, of the aromatic material in the raw material; the product of step (ii) further includes tar, which is recycled to the feed of step (i); The feed includes steam cracker tar.

[0114] Another preferred embodiment of the present invention relates to an integrated hydrotreating and steam cracker system for preparing olefin billets from crude oil containing residual oil and crude oil fractions, the system including at least one hydrotreating unit, at least A high-pressure separator, at least one visbreaker, at least one steam cracker optionally having a vapor-liquid separation device integrated therewith, and at least one steam cracker product recovery device. This can be improved or enhanced by one or more of the following features: the system further includes a steam reformer arranged at the same location as the hydrotreating device, and configured to supply hydrogen to the hydrotreating device; further features of the system It consists of a visbreaker and at least one steam cracker optionally having a vapor-liquid separation device integrated therewith in the following order and in series; the system does not include an integrated vapor-liquid separation device; the system includes an integrated vapor -Liquid separation equipment; the visbreaker is integrated with the steam cracker between the convection section and the radiant section. Yet another preferred embodiment includes a method for preparing olefin billets from billet raw materials. The method includes feeding the raw materials to a system having a hydrotreating unit and a steam cracker. The improvement includes directly feeding the residual oil-containing material to the system. Hydrotreating unit and hydrotreating the material containing residual oil, visbreaking the effluent of the hydrotreating unit in the visbreaker, and then as the effluent of the steam cracker to obtain C2-C6 olefin billet and single ring At least One, it can be improved or enhanced by an embodiment in which substantially all of the visbreaker effluent is supplied to the convection section of the steam cracker, where it is mixed with steam and then sent to In a vapor-liquid separation plant integrated with a steam cracker to provide a first stream consisting essentially of vapor materials and a second stream consisting essentially of non-vapor materials, and then the vapor materials are cracked in the radiant section of the steam cracker And the steam cracker effluent containing at least one of C2-C6 olefin billet and monocyclic aromatic billet material is recovered. Yet another preferred embodiment of the present invention is a method comprising feeding a feed stream containing residual oil to a system according to any one of the system embodiments described in the present disclosure, preferably those of the preferred embodiment set forth in this paragraph In the system, at least one product selected from C2-C6 olefin billet and monocyclic aromatic billet is obtained from the steam cracker product recovery device.

[0115] There are some other preferred embodiments of the method of the present invention can be described as follows: (i) from the residual oil hydrotreating unit

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Obtain the effluent in Yuanzhong, where the effluent contains 650 °F + (343 °C +) residual oil; (ii) separate the effluent into a top stream and a bottom stream in a separator; then (iii) remove the top stream from The separator is sent to the steam cracker; (iv) the top stream is steam cracked in the steam cracker and the steam cracker product is obtained from the steam cracker, and the product includes the olefin billet. Preferably, step (iii) is characterized by conveying the top stream as steam from the separator to the steam cracker. The separator may include at least one of a visbreaker, a flash tank, a high-pressure separator, and a vapor-liquid separator. It should be understood that it can be demonstrated that there are small differences between these devices, and these terms are often used interchangeably. The separation step may include visbreaking the effluent and separating the vapor from the liquid.

[0116] Preferably, the method further comprises the step of flashing the effluent through at least one pressure drop before steam cracking the effluent in the steam cracker, which pressure drop reduces the pressure of the effluent in the hydrocracking unit. At least half of the material pressure. In fact, this pressure drop can basically be combined with the visbreaking operation to cause a portion of the liquid to flash into vapor in the visbreaker/separator. At least one pressure drop is generated substantially just before or within the separator. Preferably, the thermal cracking of the feedstock starts in the hydroprocessing unit, and the cracking continues in the visbreaker/separator. Surprisingly, strict hydrotreating combined with strict visbreaking is used to remove most of the 650 T + (343°C +) residual oil and even most of the 1050 T + (565°C +) residual oil. Oil cracking. Thus, most of the bottom fraction (by weight) obtained in the separation step includes residual oil with a boiling point of at least 900°F (482°C), preferably at least 1050°F+ (565°C+). In a preferred embodiment, the separation step includes separating the effluent in a vapor-liquid separation vessel such as a flash tank or a visbreaker, wherein the vessel is at least one of the following: (i) thermally integrated with a steam cracker, For example, by positioning and/or connecting pipes, a separate heat source is not required, and/or (ii) heating by a heat source other than a steam cracker.

[0117] In a preferred embodiment, the effluent in the separator/visbreaker is heated to a temperature of at least 750°F (399°C), more preferably to a temperature of at least 800°F, still more preferably to a temperature of 850°F ( 454°C), and most preferably a temperature of 750 T (399Ό) to U 900°F (482°C). It is also preferred that the effluent from the separator/visbreaker remains in the separator for at least the shortest time determined, and not longer than the longest time determined. This is a conventional method of visbreaking and flash tank operations. It is necessary to quench the bottom liquid stream in order to stop the reaction, avoid scaling or coking, and at the same time allow sufficient reaction time to make most of the residual oil (including 1050 °F + (565°C +) residual oil) fully cracked into light components. The exact timing depends on the performance of the crude oil feedstock and the performance of the effluent in the separator.

[0118] Preferably, the method of the present invention includes a step of processing the raw material containing residual oil in a hydroprocessing unit, wherein the processing includes the step of treating the raw material with hydrogen at 750°F (399°F) to 900°F (482°F). Combine at temperature. Preferably, the hydrogen comes from a remote source. The hydrogenation method can be carried out under a pressure of 1000-4000 psig, and the hydrogenation treatment saturates at least 20 wt%, preferably at least 40 wt% of the aromatic material in the raw material. The preferred method also includes adding steam to at least one effluent of the hydrotreating unit and the separator. After cracking the steam fraction in the steam cracker, the desired olefin billet and other products can be recovered by other known methods.

[0119] The meanings of the terms used herein adopt their ordinary meanings in the art; in particular, refer to Handbook of Petroleum Refining Processes, third edition, Robert A. Meyers, editor, McGraw-H, set 1 (2004). In addition, all patents and patent applications, test procedures (such as ASTM methods) and other documents cited herein are incorporated by reference in their entirety to the extent that this disclosure is consistent with the present invention and all permissions permitted for this introduction. Also, when the numerical lower limit and the numerical lower limit are listed in the text, the range from any lower limit to any upper limit is taken into consideration. It should also be noted that the trade names used in this article are represented by the τ" symbol or the @ symbol, indicating that the name is protected by certain trademark rights, for example, they can be registered trademarks in many jurisdictions.

[0120] The present invention has been described above with reference to many embodiments and specific examples. Based on the above detailed description, many changes

The type is obvious to those skilled in the art. All these obvious variations are within the full scope of the appended claims.

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