Systems and methods for producing olefin products from hydrocarbon feedstocks

Abstract

The invention discloses a system and a method for producing an olefin product from a hydrocarbon feedstock. The system may include a mixed feed steam cracking unit connected to an ethane steam cracking unit, wherein the mixed feed steam cracking unit produces olefins and ethane. The ethane can be further processed in an ethane steam cracking device to produce ethylene and C2 + hydrocarbons. C2 + hydrocarbons can be recovered to a mixed feed steam cracking unit.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] none. Background of the Invention A. Field of the Invention

[0002] The present invention generally relates to systems and methods for producing olefin products from hydrocarbon feedstocks. The system may include a mixed feed steam cracker coupled to an ethane steam cracker, wherein the mixed feed steam cracker produces olefins and ethane. The ethane may be further processed in the ethane steam cracker to produce ethylene and C2+ hydrocarbons. C2+ hydrocarbons can be recycled to the mixed feed steam cracker. B. Background Technology

[0003] Olefins, such as ethylene, are building blocks for a wide variety of commercially valuable polymers. Naturally occurring sources of olefins are not available in commercial quantities. Therefore, polymer producers rely on methods that convert more abundant lower alkanes into olefins. The preferred method for today's commercial-scale producers is steam cracking, a highly endothermic process in which steam-diluted alkanes are briefly subjected to temperatures of at least 800°C. The fuel requirements to generate the required temperatures and the need for equipment that can withstand them add significantly to the overall cost. In addition, high temperatures promote the formation of coke and its accumulation within the system, resulting in the need for expensive periodic reactor shutdowns for maintenance and decoking.

[0004] Methods and systems for producing olefins from crude oil have been described. For example, International Patent Application No. WO2017 / 133975 to Ward et al. describes an integrated method for converting crude oil into petrochemical products, which includes crude oil distillation, hydrocracking and steam cracking to produce petroleum products. Some methods use a mixed feed cracker (MFC). MFC can process light hydrocarbons such as ethane, propane, butane through naphtha to heavy liquid feedstocks such as diesel and hydrocracking residues to produce gasoline and most petrochemical industrial products. The MFC method can be operated based on an optimized downstream value chain between the supply of oil or natural gas as a feedstock and the market price of high value-added hydrocarbon products. However, the disadvantage of mixed feed steam crackers is that they cannot convert all feedstocks into olefins. The performance of the cracker can be optimized when compatible feeds are supplied. In most steam crackers, dedicated furnaces are usually required to achieve optimal ethane cracking. This leads to differences in the type and size of furnaces. Steam cracking causes coke (a type of carbon) to slowly deposit on the reactor walls. Decoking requires isolating the furnace from the process and then passing a stream of steam or a steam / air mixture through the furnace coils. This converts the hard, solid carbon layer into carbon monoxide and carbon dioxide. Once this reaction is complete, the furnace is returned to service. Because a lot of coking occurs within the MRC when ethane is cracked, an MRC typically requires at least two compatible furnaces to crack ethane, which affects the size of the furnaces in the MRC and makes the process less efficient and more expensive.

[0005] In general, while the technologies to produce olefins (i.e. ethylene) exist, they are energy inefficient and costly. Summary of the invention

[0006] A discovery has provided a solution to at least one problem associated with the production of olefin products (i.e., ethylene). In one aspect, the discovery can include a system for providing an ethane cracker downstream of a mixed feed cracker. Ethane is transferred from the mixed feed cracker and provided to the ethane cracker. Such an arrangement can reduce the costs associated with upgrading the cracker feed due to the reduced energy required to process ethane in the mixed feed steam cracker. In addition, such an arrangement can increase the amount of liquid hydrocarbons that can be fed to the mixed feed steam cracker.

[0007] In one aspect of the invention, a system and method for producing olefin products are described. A system can include a mixed feed steam cracking unit capable of producing an olefin product stream and an ethane (C2) product stream, a C2+ stream can be produced, a first pipeline is connected to the mixed feed steam cracking unit and the ethane steam cracking unit, and a second pipeline is connected to the ethane steam cracking unit and the mixed feed stream cracking unit. The first pipeline can receive the C2 product stream from the mixed feed steam cracking unit and provide the C2 product stream to the ethane steam cracking unit. The second pipeline can receive the C2+ stream from the ethane steam cracking unit and provide at least a portion (e.g., 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 or 95wt.% or more, or any range therein) or all of the C2+ stream to the mixed feed stream cracking unit. The first and second pipelines can each directly connect the mixed feed steam cracking unit to the ethane steam cracker. The system can also include a feed pipeline connected to the mixed feed steam cracking unit. In some aspects, the system may include an ethane feed pipeline connected to an ethane steam cracking unit. The ethane feed pipeline may be configured to provide additional ethane to the ethane steam cracking unit. In a preferred aspect, the ethane cracking unit is not included in a mixed feed steam cracking unit. The C2+ logistics may include propane, propylene, butane, butene, pentane, pentene and / or C6+ products. In some aspects, the C2+ stream may also include ethane and / or ethylene.

[0008] The present invention also describes a method for producing olefins. In one aspect, the method may include step (a), wherein in a mixed feed steam cracking unit, a mixed hydrocarbon feed stream is subjected to conditions sufficient to produce olefin products and ethane (C2) hydrocarbons. Non-limiting examples of mixed hydrocarbon feed streams may include naphtha, gas oil, middle distillates, or a combination thereof. The conditions in step (a) may include a temperature and pressure such that most of the ethane present is not cracked. For example, the conditions in step (a) may include a temperature of 600° C. to 770° C. and / or a pressure of 0.2 MPa to 0.3 MPa. In step (b), C2 hydrocarbons may be separated from the olefin products to produce a C2 hydrocarbon stream and an olefin product stream. In step (c), the C2 hydrocarbon stream may pass through an ethane steam cracking unit under conditions sufficient to produce a C2+ hydrocarbon stream. In addition to the C2+ hydrocarbon stream, ethylene may also be produced. Ethylene may be stored, transported, or provided to other processing units. The conditions in step (c) may include a temperature of 775° C. to 860° C. and / or a pressure of 0.2 MPa to 0.3 MPa. In step (d), the C2+ hydrocarbon stream may be passed through a mixed feed steam cracker. In some aspects, a second ethane feed stream may be provided to an ethane steam cracker.

[0009] The application discusses other embodiments of the present invention in full. Any embodiment discussed for one aspect of the present invention is also applicable to other aspects of the present invention, and vice versa. Each embodiment described herein should be understood as an embodiment applicable to other aspects of the present invention. It is conceivable that any embodiment or aspect discussed herein can be combined with other embodiments or aspects discussed herein and / or implemented for any method or composition of the present invention, and vice versa. In addition, the composition of the present invention can be used to realize the method of the present invention.

[0010] The following includes definitions of various terms and phrases used in this specification.

[0011] The term "C# hydrocarbons", where "#" is a positive integer, is intended to describe all hydrocarbons having # carbon atoms. Furthermore, the term "C#+ hydrocarbons" is intended to describe all hydrocarbon molecules having # or more carbon atoms. Thus, the term "C2+ hydrocarbons" is intended to describe a mixture of hydrocarbons having 2 or more carbon atoms. Thus, the term "C2+ alkanes" relates to alkanes having 2 or more carbon atoms.

[0012] "Cracking" refers to the process of breaking down organic compounds and reorganizing the molecules to produce more molecules than the original ones. During cracking, a series of reactions occur, accompanied by the transfer of hydrogen atoms between molecules. For example, naphtha can undergo thermal cracking to form ethylene and hydrogen.

[0013] "Hydrocarbons" are generally defined as molecules consisting primarily of carbon and hydrogen atoms. Hydrocarbons may also include other elements, such as, but not limited to, halogens, metallic elements, nitrogen, oxygen, and / or sulfur. Hydrocarbon fluids may include, entrain, or be entrained in non-hydrocarbon fluids, such as hydrogen, nitrogen, carbon monoxide, carbon dioxide, hydrogen sulfide, water, and / or ammonia.

[0014] The term "about" or "approximately" is defined as close to, as understood by one of ordinary skill in the art. In a non-limiting embodiment, the term is defined as within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0015] The terms "wt. %, "vol. %" or "mol. %" refer to the weight percent of a component, the volume percent of a component or the mole percent of a component, respectively, based on the total weight, the total volume or the total number of moles of the material including the component. In a non-limiting example, 10 grams of a component in 100 grams of a material is 10 wt. % of the component.

[0016] The term "substantially" and variations thereof are defined to include ranges within 10%, within 5%, within 1%, or within 0.5%.

[0017] The terms "inhibit" or "reduce" or "prevent" or "avoid" or any variation of these terms when used in the claims and / or specification include any measurable reduction or complete inhibition to achieve a desired result.

[0018] The term "effective" as used in this specification and / or claims means sufficient to achieve a desired, intended, or expected result.

[0019] In the claims or description, when "a" or "an" is used in conjunction with the terms "includes," "comprising," "containing," or "having," it may mean "one," but is also consistent with the meaning of "one or more," "at least one," and "one or more."

[0020] The words "comprise" (and any form of including, such as "comprises" and "comprises"), "have" (and any form of having, such as "have" and "has"), "include" (and any form of including, such as "includes" and "include"), or "contain" (and any form of containing, such as "contains" and "contain") are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0021] The systems and methods of the present invention may "comprise," "consist essentially of," or "consist of" particular ingredients, components, compositions, etc. disclosed throughout the specification. With respect to the transitional phrase "consist essentially of," in one non-limiting aspect, a fundamental and novel feature of the systems and methods of the present invention is that they enable the production of olefin products (e.g., ethylene) in a cost and energy efficient manner by having an ethane steam cracker capable of receiving ethane from a mixed feed steam cracker, and feeding the C2+ products produced by the ethane steam cracker to the mixed feed steam cracker.

[0022] Other objects, features and advantages of the present invention will become apparent from the following drawings, detailed descriptions and examples. However, it should be understood that although the drawings, detailed descriptions and examples show specific embodiments of the present invention, they are given by way of illustration only and are not intended to be limiting. In addition, it is contemplated that from this detailed description, those skilled in the art will clearly understand the changes and modifications within the spirit and scope of the present invention. In further embodiments, the features of a particular embodiment may be combined with the features of other embodiments. For example, the features of one embodiment may be combined with the features of any other embodiment. In further embodiments, additional features may be added to the particular embodiments described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Advantages of the present invention will become apparent to those skilled in the art from the following detailed description with reference to the accompanying drawings.

[0024] FIG. 1 illustrates an embodiment of a system for producing olefin products from a hydrocarbon feed provided to a mixed hydrocarbon feed steam cracking unit.

[0025] While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings. The drawings may not be drawn to scale. DETAILED DESCRIPTION

[0026] A discovery has provided a solution to at least one problem associated with steam cracking of a mixed hydrocarbon feed. In one aspect, a mixed hydrocarbon feed can be fed to a mixed hydrocarbon steam cracking unit to produce petroleum products and ethane. The ethane can be fed to a separate ethane cracking unit to produce ethylene and / or a C2+ hydrocarbon stream that can be recycled to the mixed hydrocarbon stream cracking unit. The advantage of this unit is that the mixed hydrocarbon steam cracking unit can perform C2+ cracking under optimal conditions, while the ethane steam cracking unit can perform ethane cracking under optimal conditions. These and other non-limiting aspects of the invention will be discussed in further detail in the following sections with reference to the accompanying drawings.

[0027] Referring to FIG. 1 , a system 100 for producing olefin products is described. The system 100 may include a feed preparation unit 102, a mixed feed steam cracking unit 104, and an ethane steam cracking unit 106. Crude oil 108 enters feed separation 102. Crude oil is unrefined petroleum extracted from geological formations. The term crude oil may also include oil that has been subjected to water-oil separation and / or gas-oil separation and / or desalting and / or stabilization treatment. Non-limiting examples of crude oil include Arab heavy crude oil, Arab light crude oil, other Gulf crude oil, Brent crude oil, North Sea crude oil, North African and West African crude oil, Indonesian crude oil, Chinese crude oil, West Texas crude oil, and mixtures thereof, and also include shale oil, oil sands, condensate, and bio-based oil. The crude oil used as feed for the method of the present invention is preferably conventional oil, and its API gravity is greater than 20°API (measured according to ASTMD287 standard). On the one hand, the crude oil used in the method of the present invention is a light crude oil with an API gravity greater than 30°API; on the other hand, the crude oil used in the method of the present invention may include Arab light crude oil. The API gravity of Arabian Light Crude Oil is usually between 32-36° API and the sulfur content is between 1.5-4.5wt.%.

[0028] In the feed preparation device, crude oil can be separated into different crude oil fractions according to the difference in boiling point. For example, a fractionation tower or a combination of multiple fractionation towers can be used to distill crude oil, and the fractionation tower is used to separate crude oil into fractions by fractionation. The resulting crude oil can be processed in an atmospheric distillation unit to separate gas oil and lighter fractions from high boiling point components to obtain a mixed hydrocarbon feed 110. The mixed hydrocarbon feed may include hydrocarbons with a boiling point higher than 560°C. Non-limiting examples of various fraction hydrocarbon feeds with a boiling point higher than 560°C include vacuum gas oil, middle distillate oil, naphtha, kerosene, liquefied petroleum gas, or mixtures thereof.

[0029] The mixed hydrocarbon feed 110 may leave the feed treatment unit 102 and enter the mixed feed cracking unit 104. In the mixed feed cracking unit 104, the mixed feed is steam cracked at a temperature of 600° C. to 770° C. (e.g., 600° C., 625° C., 650° C., 675° C., 700° C., 725° C., 950° C., 770° C., or any value or range therebetween) and / or a pressure of 0.2 MPa to 0.3 MPa (e.g., 0.2 MPa, 0.21 MPa, 0.22 MPa, 0.23 MPa, 0.24 MPa, 0.25 MPa, 0.26 MPa, 0.27 MPa, 0.28 MPa, 0.30 MPa, or any value or range therebetween). Ethane may not crack at such a temperature and pressure. In the steam cracking process, by diluting the mixed hydrocarbon feed with steam, and heating the mixture in a furnace under oxygen-free conditions, saturated hydrocarbons are decomposed into smaller, usually unsaturated hydrocarbons, such as ethylene and propylene. The residence time of the steam cracking reaction can reach 50 to 1000 milliseconds. The mixed steam cracking unit can have a fractionation unit (not shown) or a gas fractionation unit (not shown), which can separate ethane from the olefin product stream. Such fractionation units are well known in the art. Ethane stream 112 can leave the mixed hydrocarbon feed steam cracking unit 104, and enter the ethane steam cracking unit 106. The olefin product stream 114 can leave the mixed feed steam cracking unit 104 and be stored, transported or used in other processing units. In some aspects, additional ethane stream 116 can enter the ethane steam cracking unit 106. The ethane stream can include other gaseous compounds, such as propane and butane. In the ethane steam cracking unit 106, gaseous ethane can be diluted with steam and heated in one or more furnaces to a temperature of 775°C to 860°C (e.g., 775°C, 800°C, 825°C, 850°C, 860°C, or any value or range therebetween) and / or a pressure of 0.2 MPa to 0.3 MPa (e.g., 0.2 MPa, 0.21 MPa, 0.22 MPa, 0.23 MPa, 0.24 MPa, 0.25 MPa, 0.26 MPa, 0.27 MPa, 0.28 MPa, 0.30 MPa, or any value or range therebetween) to produce ethylene and / or C2+ hydrocarbons. The C2+ hydrocarbon stream 118 can leave the ethane steam cracking unit 106 and enter the mixed feed steam cracker 104 for further processing. In some embodiments, the C2+ hydrocarbon stream 118 is no longer recycled to the mixed feed steam cracking unit 104.

[0030] Although the embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made herein without departing from the spirit and scope of the embodiments defined in the appended claims. In addition, the scope of the present application is not limited to the specific embodiments of the methods, machines, manufactures, material compositions, means, methods and steps described in the specification. It can be easily understood by a person of ordinary skill in the art from the above disclosure that existing or later developed methods, machines, manufactures, material compositions, devices, methods or steps that perform substantially the same functions as the corresponding embodiments described herein or achieve substantially the same results can be utilized. Therefore, the attached claims are intended to include these processes, machines, manufactures, material compositions, devices, methods or steps within their scope.

Claims

1. A system for producing olefins, characterized in that The system includes: a mixed feed steam cracking unit capable of producing an olefin product stream and an ethane (C2) product stream; an ethane steam cracker capable of producing a C2+ stream; and a first pipeline connected to the mixed feed steam cracking unit and the ethane steam cracking unit, the first pipeline being capable of receiving a C2 product stream from the mixed feed steam cracking unit and providing the C2 product stream to the ethane steam cracking unit; A second pipeline is connected to the ethane steam cracking unit and the mixed feed stream cracking unit, wherein the second pipeline is capable of receiving the C2+ stream from the ethane steam cracking unit and providing the C2+ stream to the mixed feed stream cracking unit.

2. The system according to claim 1, characterized in that Wherein the first and second conduits each directly connect the mixed feed steam cracker to the ethane steam cracker.

3. The system according to any one of claims 1 to 2, characterized in that It also includes a feed conduit connected to the mixed feed steam cracker.

4. The system according to any one of claims 1 to 3, characterized in that Also included is an ethane feed pipeline connected to the ethane steam cracking unit, wherein the ethane feed pipeline is configured to provide additional ethane to the ethane steam cracking unit.

5. The system according to any one of claims 1 to 4, characterized in that The ethane cracking unit is not included in the mixed feed steam cracking unit.

6. A method for producing olefins, characterized in that The method includes: (a) subjecting a mixed hydrocarbon feed stream to conditions sufficient to produce olefin products and ethane (C2) hydrocarbons in a mixed feed steam cracker; (b) separating the C2 hydrocarbons from the olefin products to obtain a C2 hydrocarbon stream and an olefin product stream; (c) passing the C2 hydrocarbon stream to an ethane steam cracking unit under conditions sufficient to produce a C2+ hydrocarbon stream; and (d) Feeding the C2+ hydrocarbon stream to a mixed feed steam cracking unit.

7. The method according to claim 6, characterized in that Also included is providing a second ethane feed stream to the ethane steam cracker.

8. The method according to any one of claims 6 to 7, characterized in that The conditions in step (a) include temperatures and pressures such that a substantial portion of the ethane present is not cracked.

9. The method according to any one of claims 6 to 8, characterized in that The conditions in step (a) include a temperature of 600°C to 770°C.

10. The method according to any one of claims 6 to 9, characterized in that The conditions in step (a) include a pressure of 0.2 MPa to 0.3 MPa.

11. The method according to any one of claims 6 to 10, characterized in that The mixed hydrocarbon feed stream comprises naphtha, gas oil or a combination thereof.

12. The method according to any one of claims 6 to 11, characterized in that The conditions in step (c) include a temperature of 775°C to 860°C.

13. The method according to any one of claims 6 to 12, characterized in that The conditions in step (c) include a pressure of 0.2 MPa to 0.3 MPa.

14. The method according to any one of claims 6 to 13, characterized in that Also included is the production of ethylene from cracking of C2 hydrocarbon streams.

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