Methods and systems for enhanced olefin production by hydrocracking heavy hydrocarbons

Abstract

Provided here are methods and systems for enhanced olefin production by hydrocracking heavy hydrocarbons. One such method for producing olefins includes separating a naphtha feed stream containing C5-C12 hydrocarbons to produce a C5 rich feed stream and a heavy naphtha stream, catalytically cracking the C5 rich feed stream in a presence of hydrogen to produce a first intermediate stream containing at least ethane, separating aromatics from the first intermediate stream to produce an aromatic-rich stream and a hydrocracked stream, and supplying the hydrocracked stream to a steam cracker, thereby to produce at least ethene.

Description

24CHEM0019-WO-ORD1METHODS AND SYSTEMS FOR ENHANCED OLEFIN PRODUCTION BY HYDROCRACKING HEAVY HYDROCARBONSTECHNICAL FIELD

[0001] The present disclosure generally relates to methods and systems for enhanced olefin production. More specifically, the present disclosure relates to methods and systems for enhanced olefin production by hydrocracking heavy hydrocarbons.BACKGROUND

[0002] In a typical liquid to chemical complex, mixed C4 streams, along with C2 and C3 hydrocarbons from various refinery process units, are directly fed to a steam cracker. Similarly, naphtha streams containing a wide range of material are directly fed to steam cracker. However, direct feeds to the steam cracker result in increased pygas and pyoil along with reduced desired olefin products, such as ethene and propene. To resolve this, Applicant has previously developed various technologies to condition the C4-steam cracker feed streams to produce ethane and propane in the presence of hydrogen prior to feeding to a steam cracker to increase ethene and propene yield therefrom. However, Applicant has recognized there remains a need for conditioning heavy hydrocarbons, such as C5+, including naphtha, for enhanced and cost-effective processes to produce olefins to be implemented with current technology design processes.SUMMARY

[0003] There remains a need for conditioning heavy hydrocarbons, such as Cs+, including naphtha, for enhanced and cost-effective processes to produce olefins to be implemented with current technology design processes. Applicant has recognized that catalysts utilized for C4 processing may be utilized to process heavier hydrocarbons based on high reaction activity. Embodiments of the present disclosure substantially improve the versatility of olefin production from various mixed hydrocarbon streams, such as C2-C12 streams, including naphtha, to a steam cracker to product desired olefins, such as ethene and propene.

[0004] Examples set forth herein include methods and systems for enhanced olefin production by hydrocracking heavy hydrocarbons. One such method for producing olefins includes separating a naphtha feed stream containing C5-C12 hydrocarbons to produce a C5 rich feed stream and a heavy naphtha stream, catalytically cracking the C5 rich feed stream in a presence of hydrogen to produce a first intermediate24CHEM0019-WO-ORD2stream containing at least ethane, separating aromatics from the first intermediate stream to produce an aromatic-rich stream and a hydrocracked stream, and supplying the hydrocracked stream to a steam cracker, thereby to produce at least ethene.

[0005] In another example, the method further includes separating a C2-C4 feed stream to produce a C2 stream and a C3-C4 stream, catalytically cracking the C3-C4 stream in a presence of hydrogen to produce a second intermediate stream, separating aromatics from the second intermediate stream to produce the aromatic-rich stream and the hydrocracked stream, and supplying the C2 stream and the hydrocracked stream to the steam cracker, thereby to produce at least ethene.

[0006] In another example, the method further includes separating a C2-C4 feed stream to produce a C2-C3 stream and a hydrocracker feed stream, the hydrocracker feed stream containing butane, optionally separating the C2-C3 stream to produce a C2 rich stream and a C3 rich stream, the C3 rich stream to be supplied to a propane dehydrogenation unit, thereby to produce propylene, catalytically cracking the hydrocracker feed stream in a presence of hydrogen to produce a second intermediate stream containing substantially ethane and propane, separating aromatics from the second intermediate stream to produce the aromatic-rich stream and the hydrocracked stream, and supplying the C2-C3 stream, or the optional C2 rich stream, in addition to the hydrocracked stream to the steam cracker, thereby to produce ethene and propene.

[0007] In still another example, the method further includes further separating the naphtha feed stream to produce a Ce rich stream in addition to the Cs rich feed stream and the heavy naphtha stream, catalytically cracking the Cerich stream in a presence of hydrogen to produce a third intermediate stream, and separating aromatics from the third intermediate stream to produce the aromatic-rich stream and the hydrocracked stream.

[0008] In another example, the method further includes treating a Ce aromatic feed to produce a Ce stream containing substantially Ce paraffins and Ce naphthenes, catalytically cracking the Ce stream in a presence of hydrogen to produce a third intermediate stream, and separating aromatics from the third intermediate stream to produce the aromatic-rich stream and the hydrocracked stream.

[0009] Some examples of the present disclosure are directed to, for example, a system including a naphtha separation unit configured to receive one or more naphtha feed streams and to produce a Cs rich feed stream and a heavy naphtha stream, an aromatic processing unit in fluid communication with the naphtha separation unit and configured to receive the heavy naphtha stream and to produce benzene and dimethylbenzene, a Cs reaction unit in fluid communication with the naphtha separation unit and24CHEM0019-WO-ORD3configured to receive and crack the Cs rich feed stream and to produce a first intermediate stream containing ethane and aromatics, a separation unit in fluid communication with the Cs reaction unit and the naphtha separation unit and configured to separate aromatics from the first intermediate stream and to produce a hydrocracked stream containing ethane and an aromatic-rich stream, and a steam cracker unit in fluid communication with the separation unit and configured to receive the hydrocracked stream and to produce at least ethene.

[0010] In another example, the system further includes the naphtha separation unit further configured to produce a Ce rich stream, and a Ce+ reaction unit in fluid communication with the naphtha separation unit and the separation unit and configured to receive and crack the Ce rich stream in a presence of hydrogen to produce a second intermediate stream containing ethane and aromatics fed to the separation unit to produce the hydrocracked stream and the aromatic-rich stream.

[0011] In yet another example, the system further includes a Ce aromatic saturation unit in fluid communication with the Ce+ reaction unit and configured to treat a Ce aromatic feed to produce a Ce stream containing substantially Ce paraffins and Ce naphthenes to be fed to the Ce+ reaction unit.

[0012] In another example, the system further includes a C2 separation unit configured to receive a C2-C4 feed stream supplied from one or more of a crude distillation unit, a diesel hydrotreater unit, or a hydrocracker unit and to produce a C2-rich stream containing substantially ethane fed to the steam cracker unit and a C3-C4 stream, and a C4 reaction unit in fluid communication with the C2 separation unit and the separation unit and configured to receive and crack the C3-C4 stream and a mixed C4 stream supplied from a total hydrogenation unit in a presence of hydrogen to produce a third intermediate stream containing ethane and aromatics fed to the separation unit to produce the hydrocracked stream and the aromatic-rich stream.

[0013] In yet another example, the system further includes a methane unit configured to received recovered methane from the C4 reaction unit, the hydrocracked stream, or a steam cracker product stream containing produced ethene.

[0014] In another example, the system further includes a C3 separation unit configured to receive a C2-C4 feed stream supplied from one or more of a crude distillation unit, a diesel hydrotreater unit, or a hydrocracker unit and to produce a hydrocracker feed containing mixed butanes and to further produce a C2-C3 stream, and a C4 reaction unit in fluid communication with the C3 separation unit and the separation unit and configured to receive and crack the hydrocracker feed in a presence of hydrogen to produce a24CHEM0019-WO-ORD4third intermediate stream containing ethane, propane, and aromatics fed to the separation unit to produce the hydrocracked stream and the aromatic-rich stream.

[0015] In another example, the system further includes a C2 separation unit in fluid communication with the C3 separation unit and configured to receive and separate the C2-C3 stream to produce a C2 rich stream and a C3 rich stream, a propane dehydrogenation unit in fluid communication with the C2 separation unit and configured to dehydrogenate the C3 rich stream, thereby to produce propylene, and wherein the steam cracker unit is further configured to receive the C2 rich stream in addition to the hydrocracked stream, thereby to produce ethene.

[0016] Aspects and advantages of these exemplary examples and other examples, are discussed in detail herein. Moreover, it is to be understood that both the foregoing information and the following detailed description provide merely illustrative examples of various aspects and examples, and are intended to provide an overview or framework for understanding the nature and character of the claimed aspects and examples. Accordingly, these and other objects, along with advantages and features of the present disclosure, will become apparent through reference to the following description and the accompanying drawings. Furthermore, it is to be understood that the features of the various examples described herein are not mutually exclusive and may exist in various combinations and permutations.BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are included to provide a further understanding of the examples of the present disclosure, are incorporated in and constitute a part of this specification, illustrate examples of the present disclosure, and together with the detailed description, serve to explain principles of the examples discussed herein. No attempt is made to show structural details of this disclosure in more detail than may be necessary for a fundamental understanding of the examples discussed herein and the various ways in which they may be practiced. According to common practice, the various features of the drawings discussed herein are not necessarily drawn to scale. Dimensions of various features and elements in the drawings may be expanded or reduced to more clearly illustrate examples of the disclosure.

[0018] FIG. 1 is a schematic representation of an embodiment of a conventional olefin production system using a mixed feed steam cracker, according to an example.

[0019] FIG. 2 is a schematic representation of an embodiment of an olefin production system using a C2 separation unit, a Ce aromatic saturation unit, and an LTEP system to condition C3-C12 hydrocarbons24CHEM0019-WO-ORD5for enhanced steam cracker ethene production from C2-C12 hydrocarbon feed streams, according to an example.

[0020] FIG. 3 is a schematic representation of an embodiment of an olefin production system using a C3 separation unit, a Ce aromatic saturation unit, and an LTEP system to condition C4-C12 hydrocarbons for enhanced steam cracker ethene and propene production from C2-C12 hydrocarbon feed streams, according to an example.

[0021] FIG. 4 is a flow chart of a method in which light olefin production may be increased by separating C2-C4 feed streams with a C2 separation unit and by hydrocracking to feed a steam cracker unit, according to one example.

[0022] FIG. 5 is a flow chart of a method in which light olefin production may be increased by separating C2-C4 feed streams with a C3 separation unit and by hydrocracking to feed a steam cracker unit, according to one example.

[0023] FIG. 6 is a flow chart of a method in which light olefin production may be increased by separating and hydrocracking heavy hydrocarbons feed streams to feed a steam cracker unit, according to one example.

[0024] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated into other embodiments without further recitation.DETAILED DESCRIPTION

[0025] Olefins are used to produce various products including plastics, medicines, and other useful materials. In many refinery operations, olefins are maximized to produce increased revenue. Conventionally, mixed feed streams would be fed directly to the steam cracker, resulting in poor olefin production. Improvements for increased production of olefins include conditioning of the mixed feed streams to produce a better product from the steam cracker. One such technology, referred to as BUTEP, involves hydrocracking a paraffin stream to produce ethane and propane, which are known feeds to increase ethene and propene from a steam cracker. Applicant has previously developed the BUTEP technology to hydrocrack mixed butane feeds to produce ethane and propane in the presence of hydrogen prior to feeding to a steam cracker to increase ethene and propene yield therefrom. Additionally, Applicant recognized that heavier hydrocarbons, such as Cs+ hydrocarbons, including naphtha, may also be conditioned to produce a better product from the steam cracker. Applicant has also recognized that C3+24CHEM0019-WO-ORD6hydrocarbons may also be conditioned to produce ethane from the steam cracker. Methods and systems disclosed herein condition both light and heavy hydrocarbons streams, including C3-C12 hydrocarbons, and produce a better product from the steam cracker, such as ethene and propene, through use of an “liquid to ethane and propane” (LTEP) technology.

[0026] It is known chemistry that mixed feeds to a steam cracker containing a large number of carbons reduce ethene and propene olefin production while simultaneously increasing pygas and pyoil yields. Therefore, the intent of this disclosure is to make feeds to a steam cracker as light as possible to increase light olefin production. Various technologies have been deployed in refineries to crack heavy molecules into lighter molecules to make a better feed to the steam cracker. However, naphtha has been particularly difficult due to a high iso-to-normal isomer ratio that makes for a poor steam cracker feed. Attempts to adjust the iso-to-normal isomer ratio have included specialized hydrocracker and isomerization designs however, the resulting capital expenses and operational expenses can be exceedingly high and furthermore, these reactions are often equilibrium restricted, so achieving an appreciable conversion to only normal isomers is exceedingly difficult. Thus, conventional processes to convert naphtha to light hydrocarbon feeds have been limited. Provided here are systems and methods involving LTEP technology to process C3-C12 hydrocarbons, including naphtha, into ethane and propane that yields an increased light olefin production, such as ethene and propene, and a reduced pygas and pyoil yield from a steam cracker.

[0027] The present disclosure benefits existing petrochemical complexes, such as refinery and chemical operations, by implementing LTEP technology processes to enhance olefin yield using separation and hydrocracking heavy hydrocarbons to increase olefin production, thereby to reduce the cost of catalyst and utilities compared to conventional processes.

[0028] The description may use the phrases “in some examples,” “in various examples,” “in an example,” or “in examples,” which may each refer to one or more of the same or different examples. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to examples of the present disclosure, are synonymous. The term “plurality” as used herein refers to two or more items or components. The terms “about” or “approximately” are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting example, these terms are defined to be within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5% of the specified value. In some examples, “about” refers to the specified value.

[0029] The terms “removing,” “removed,” “reducing,” “reduced,” or any variation thereof, when used in the claims and / or the specification includes any measurable decrease of one or more components in a24CHEM0019-WO-ORD7mixture to achieve a desired result. The use of the words “a” or “an” when used in conjunction with any of the terms “comprising,” “including,” “containing,” or “having,” in the claims or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The terms “wt. %”, “vol. %”, or “mol. %” refers to a weight, volume, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, which includes the component. In a non-limiting example, 10 grams of a component in 100 grams of the material is 10 wt. % of the component. The term “rich”, such as X-rich stream, means that the stream includes at least 50 mol. % of the named compound or class of compounds, such as at least 60 mol. %, at least 70 mol. %, at least 80 mol. %, at least 90 mol. %, at least 95 mol. %, at least 98 mol. %, at least 99 mol. %, or 100 mol. %, or any sub-ranges therebetween.

[0030] As used herein, the term “Cx” compounds, in which x is a positive integer value, refers to hydrocarbon-based compounds, each compound containing x carbon atoms. For example, a C3 compound refers to a hydrocarbon-based compound containing 3 carbon atoms. As used herein, the term “Cx and / or lighter compounds,” or similar used terms, in which x is a positive integer value, refers to hydrocarbonbased compounds, each compound containing at least x carbon atoms. For example, a C3 and / or lighter compounds refers to a mixture that substantially contains or entirely contains hydrocarbon-based compounds, each compound containing 3 or less (e.g., 3, 2, or 1) carbon atoms. Similarly, “<C3” refers to 3 carbon atoms or lesser carbon atoms containing compounds.

[0031] As used herein, when a first component is described as receiving (or being configured to receive) a stream from a second component, or when a first component is described as providing (or being configured to provide) a stream to a second component, the first and second components may be alternatively described as being in fluid communication, or in fluid connection, with one another. It may be appreciated that, for the various streams discussed herein, a given stream substantially contains the compound or class of compounds in the name of the stream (e.g., an ethene product stream substantially contains ethene, a C4 olefin stream substantially contains C4 olefins), and the stream may also include other components.

[0032] FIG. 1 is a schematic representation of an embodiment of a conventional olefin production system 100 using a mixed feed steam cracker 108, according to an example. The refinery system 100 includes various units, such as a crude distillation unit (CDU) 102, a saturated gas plant (SGP) 104, a diesel hydrotreater unit (DHT) 106, a vacuum distillation unit (VGU) 112, a hydrocracking unit (HCU) 110, and a mixed feed steam cracker unit (MFSC) 108. Each of the units may be utilized to produce a feed24CHEM0019-WO-ORD8to the MFSC 108. The olefin production system 100 further includes various streams, such as streams 150, 152, 154, 156, 158, 160, 162, 164, 166, 168, and 170, to interconnect the process system. Additionally, the MFSC 108 produces various products such as, but not limited to, fuel gas, ethene, propene, butene- 1, MTBE, benzene, mixed dimethylbenzene, and pyoil. The example of FIG. 1 omits various principle and auxiliary streams necessary for operation. However, the example of FIG. 1 may be used to understand the complexity of an olefin production system and various products that may be produced from the MFSC 108.

[0033] As illustrated, the various units may be configured to provide a feed stream to the MFSC 108. In some examples, the stream 162 from the SGP 104, the stream 154 from the CDU 102, the streams 164 or 166 from the DHT 106, and the stream 170 from the HCU may each independently feed the MFSC 108 with a supply stream to steam crack into their respective products. In one example, the stream 162 contains C2-C4 hydrocarbons. In another example, the stream 150 is a liquid hydrocarbon feed which may be any crude oil, such as a crude oil extracted from subterranean formations. In yet another example, the streams 154, 164, and 170 contain naphtha, including straight run naphtha, and hydrocracked naphtha, defined by a C5-C12 hydrocarbon with a boiling point of about 40 degrees Celsius to about 210 degrees Celsius.

[0034] The focus of the present disclosure is to implement innovative treatments of C2-C12 hydrocarbon feed streams to the MFSC 108 to increase production of desirable light olefin products. These treatments will be discussed in FIGS. 2-6.

[0035] FIG. 2 is a schematic representation of an embodiment of an olefin production system 200 using a C2 separation unit 228, a Ce aromatic saturation unit 224, and an LTEP system 226 to condition C3-C12 hydrocarbons for enhanced steam cracker ethene production from C2-C12 hydrocarbon feed streams, according to an example. The olefin production system 200 further includes various units, such as a hydrogen supply unit 202, a steam cracker unit 208, and an aromatic processing unit 222. Generally, the LTEP system 226 may be utilized to produce increased ethane in the steam cracker feed stream, thereby to yield an increase ethene production from the steam cracker unit 208. The LTEP system 226 may be defined as containing one or more reaction units, one or more heating units to heat the feed to each reaction unit, and various product separation units, including associated recycle streams for unconverted C3-C12 hydrocarbons. The mentioned details of the LTEP system 226 will be discussed in greater detail in the following FIG. 3. The olefin production system 200 includes various streams, such as streams 210, 250, 252, 256, 262, 264, 266, 270, 278, 284, 286, 288, 290, 298 and optional streams 271, 273, and 275. Of those mentioned streams, streams 264, 250, 252, 290, 270, 286, and 298 may be configured to feed the24CHEM0019-WO-ORD9LTEP system 226 and streams 256, 278, and 271 may be configured to be produced by the LTEP system 226. The separation and LTEP technology process of FIG. 2 advantageously increases production of olefins, such as ethene, produced by the steam cracker unit 208 and provides economic advantages, compared to a BUTEP technology process without a C2 separation, to produce olefins from a steam cracker, such as MF SC 108.

[0036] The C2 separation unit 228 may be configured to receive a C2-C4 feed stream 262 and to produce a C2-rich stream 266 containing substantially ethane and a C3-C4 stream 264. The C2 separation unit 228 may be in fluid connection with the C2-C4 feed stream 262 source units, the steam cracker unit 208, and the LTEP system 226. In some examples, the C2-C4 feed stream 262 may be supplied from a crude distillation unit, a hydrotreater unit, and / or a hydrocracker unit. In some examples, the C2-C4 feed stream 262 may be a collection of alkanes, or “paraffins,” from the aforementioned units within a saturated gas plant, such as the SGP 104 from FIG. 1. In that example, the C2-C4 feed stream 262 may be an outlet line from the saturated gas plant that feeds the C2 separation unit 228. The C2 separation unit 228 may separate and directly feed the C2-rich stream 266 to the steam cracker unit 208. The C2 separation unit 228 may be a “de-ethanizer column,” such as a distillation column. In one example, the C3-C4 stream 264 may be mixed with the paraffin stream 250 supplied from total hydrogenation unit, also referred to as a mixed C4 stream, containing mixed butanes, such as at least 2-methylpropane and n-butane. In another example, the C3-C4 stream 264 and the paraffin stream 250 may be independently fed to the LTEP system 226.

[0037] The LTEP system 226 may be configured to receive a Cs-rich stream 290. The stream 290 may supplied from a pygas hydrotreater in fluid communication to the LTEP system 226. The LTEP system 226 may be further configured to receive a naphtha-rich stream 270. The naphtha-rich stream 270 may be a supplied from one or more of a crude distillation unit, a diesel hydrotreater unit, or a hydrocracker unit and may contain substantially C5-C12 hydrocarbons. The streams 270 and 290 may be combined to collectively feed the LTEP system 226. In other examples, as illustrated, the naphtha-rich stream 270 and the Cs-rich stream 290 may be independently fed to the LTEP system 226.

[0038] The Ce aromatic saturation unit 224 may be in fluid communication with the LTEP system 226 and an aromatic complex (not shown). In some examples, the Ce aromatic feed stream 284 may be a recycled stream from the aromatic complex (not shown) which produces the Ce aromatic feed stream 284 rich in Ce aromatics. Further, the Ce aromatic saturation unit 224 may be configured to treat a Ce aromatic feed stream 284 to produce a Ce stream 286 containing substantially Ce paraffins and naphthenes. The Ce stream 286 may be configured to feed the LTEP system 226. In some examples, the Ce aromatic saturation24CHEM0019-WO-ORD10unit 224 may contain a partial ring opening section or a full ring opening section. The ring opening section within the Ce aromatic saturation unit 224 may be configured to break Ce naphthene rings formed as a result of saturation of the Ce aromatic feed stream 284 to produce Ce paraffins and to further increase paraffins to naphthenes ratio in the Ce stream 286. In some embodiments, the Ce aromatic saturation unit 224 may not require a ring opening section and directly feed naphthenic Ce hydrocarbons to the LTEP system 226.

[0039] The LTEP system 226 utilizes hydrogen and thus, the LTEP system 226 may be configured to receive hydrogen supplied by the hydrogen supply unit 202 via hydrogen-rich stream 252. The hydrogen supply unit 202 may be configured to supply hydrogen to hydrogen dependent reaction units present within the LTEP system 226.

[0040] Lastly, the LTEP system 226 may be configured to receive a recycle raffinate stream 298 from an aromatic processing unit 222. In some examples, the LTEP system 226 may be configured to produce an aromatic-rich stream 278. In other examples, the aromatic-rich stream 278 may further contain heavy naphtha, such as C7-C12 hydrocarbons. The LTEP system 226 may be fluidly connected to the aromatic processing unit 222 via the aromatic-rich stream 278. The aromatic processing unit 222 may be configured to produce benzene and dimethylbenzene via stream 288 and the recycle raffinate stream 298 rich in nonaromatic Ce+ hydrocarbons for recycle to the reaction units within the LTEP system 226.

[0041] The LTEP system 226 may be configured to produce the aromatic-rich stream 278 and a hydrocracked stream 256 containing substantially ethane produced by the process of the LTEP system 226. In some examples, methane may be produced by the LTEP system 226, as illustrated via stream 271 for collection via the methane unit 209. The LTEP system 226 may contain reaction units and a separation unit, as shown in FIG. 3, which utilize “butane to ethane and propane” (BUTEP) technology. The BUTEP technology may use a zeolite catalyst, present in a reaction vessel within the reaction units, to initiate a mechanism in the production of, for example, ethane through P-scission by hydrocracking received C3-C12 hydrocarbons from the feed streams, such as streams 264, 250, 290, 270, 286 and recycle raffinate stream 298, in a presence of hydrogen to produce the hydrocracked stream 256 containing at least ethane. In some examples, the catalyst may be a zeolite such as ZSM-5 containing about 0.3 wt. % platinum within the LTEP system 226 reaction vessels. The LTEP catalyst can be defined as a bifunctional catalyst containing a hydrogenation metal, such as, for example, Pt, Pd, Ni, or the like, and a zeolite with Bronsted acidity (greater than 50% of acid sites being Bronsted acid sites vs. Lewis acid sites). The zeolite can be defined as containing alumina and silica heteroatoms, or substituted heteroatoms such as Fe, P, Ge, B, or24CHEM0019-WO-ORD11the like. Examples of zeolite frameworks that could be used are FAU, FER, MFI, CHA (SSZ-13 or S APO-34), AEI, MOR, or Beta. The LTEP system 266 may be configured to obtain up at least about 82 percent conversion of the collective C3-C12 feed streams, such as streams 264, 290, 270, 286, and 298. In some examples, the reaction unit may use a flowrate that results in a weight hourly space velocity of about 2 per hour. In one example, the reaction units of LTEP system 226 may operate at a temperature of about 350 degrees Celsius to about 500 degrees Celsius, such as about 465 degrees Celsius at a pressure of about 50 psig to about 350 psig, such as about 100 psig. In a particular example, an intermediate stream produced by the LTEP system 226 may contain about 22 percent methane, about 70 percent ethane, and about 8 percent of a mixture of benzene, toluene, and dimethylbenzene. Details of the intermediate stream produced by the LTEP system 226 will be discussed in the embodiment of FIG. 3.

[0042] The steam cracker unit 208 may be in fluid communication with the LTEP system 226, and the C2 separation unit 228. In some examples, the steam cracker unit 208 may be configured to receive the hydrocracked stream 256 and the C2-rich stream 266, and to produce a product stream 210 that contains light olefins, including ethene. The LTEP system 226 advantageously extends the usage of the catalyst in the reaction units to increase the production of ethane that results in increased production of light olefins, such as ethene by the steam cracker unit 208.

[0043] In some examples, methane recovery may be achieved by collection of methane produced within or by the LTEP system 226. For example, the methane gas produced from a reaction vessel with the LTEP system 226 may be separated via optional stream 271. In other examples, the methane gas may be separated downstream of the LTEP system 226, such as from the hydrocracked stream 256, or from the resulting product produced from the steam cracker unit 208, as shown by optional streams 273, or 275 respectively. In some examples, methane gas is not provided to the steam cracker as methane may serve as a fuel gas for other units. For example, the methane may be separated by using a demethanizer (not shown). In one example, the carbon loss resulting from the separation of methane through either optional streams 271, 273, or 275, may be from about 1 weight percent to about 10 weight percent of the carbon within the hydrocracker feed 264, dependent on the severity of the reaction.

[0044] FIG. 3 is a schematic representation of an embodiment of an olefin production system 300 using a C3 separation unit 312, a Ce aromatic saturation unit 324, and an LTEP system 326 to condition C4-C12 hydrocarbons for enhanced steam cracker ethene and propene production from C2-C12 hydrocarbon feed streams, according to an example. FIG. 3 illustrates an example of how various LTEP reactor sections could be integrated for desired conversions. For example, the configuration of the example of FIG. 3 may24CHEM0019-WO-ORD12be utilized to increase production of ethene and propene by the steam cracker 308, as compared to the example of FIG. 2 which may be utilized to increase production of ethene by the steam cracker 208. The olefin production system 300 includes various units, such as, a C3 separation unit 312, a hydrogen supply unit 302, a C4 reaction unit 306, a Cs reaction unit 316, a Ce+ reaction unit 320, a naphtha separation unit 314, a separation unit 318, an aromatic processing unit 322, an Ce aromatic saturation unit 324, C2 separation unit 328, and a steam cracker unit 308. The olefin production system 300 includes various streams such as streams 310, 348, 350, 352, 353, 354, 356, 362, 364, 366, 368, 370, 372, 374, 376, 378, 380, 382, 384, 386, 388, 390, 392, 394, 396, and 398.

[0045] The “liquid to ethane and propane” (LTEP) system 326 of the example of FIG. 3 contains the units to process the C4-C12 hydrocarbon feed streams, including naphtha, as discussed herein. The LTEP system 326 may be defined as containing the naphtha separation unit 314, the C4 reaction unit 306, the C5 reaction unit 316, the Ce+ reaction unit 320, and a separation unit 318. The LTEP system 326 may be configured to receive the hydrocracker feed 364 containing mixed butanes from the C3 separation unit 312, the mixed C4 feed 350 from total hydrogenation unit, the Cs rich stream 390, the naphtha stream 370, and the Ce stream 386, and to produce benzene and dimethylbenzene via stream 388 and the hydrocracked stream 356.

[0046] The C3 separation unit 312 may be configured to receive a C2-C4 feed stream 362 and to produce a hydrocracker feed 364 rich in butanes, and a C2-C3 rich stream 366. The C3 separation unit 312 may be in fluid connection with a crude distillation unit, a hydrotreater unit, and / or a hydrocracker unit, as shown in FIG. 1, a C4 reaction unit 306 of the LTEP system 326, a hydrogen supply unit 302, the steam cracker unit 208, and optionally the C2 separation unit 328. In some examples, the C2-C4 feed stream 362 may be supplied from a crude distillation unit, a hydrotreater unit, or a hydrocracker unit. In some examples, the C2-C4 feed stream 362 may be a collection of alkanes, or “paraffins,” from the aforementioned units within a saturated gas plant, such as the SGP 104 from FIG. 1. In that example, the C2-C4 feed stream 362 may be an outlet line from the saturated gas plant that feeds the C3 separation unit 312. The C2-C3 rich stream 366 may be combined with the hydrocracked stream 356 containing substantially ethane and propane and fed to the steam cracker unit 308. In one example the C2-C3 rich stream 366 may be directly fed to the steam cracker unit 308. In another example, the C2-C3 rich stream 366 may be directly fed, via stream 348, to the C2 separation unit 328. In still another example, the C2-C3 rich stream 366 may be partially fed via stream 348 to the C2 separation unit 328. The C3 separation unit 312 may be a “de-propanizer column,” such as a distillation column. In one example, the hydrocracker feed 364 may be mixed with a paraffin24CHEM0019-WO-ORD13stream 350 supplied from total hydrogenation unit, also referred to as a mixed C4 stream, containing mixed butanes, such as at least 2-methylpropane and n-butane. In another example, the hydrocracker feed 364 and the paraffin stream 350 may be independently fed to the LTEP system 326, such as the C4 reaction unit 306 of the LTEP system 326.

[0047] The C2 separation unit 328 may provide an optional, or alternative, pathway to process the C2-C3 rich stream 366 upstream of the steam cracker unit 308. For example, the C2 separation unit 328 may be configured to receive the entirety, or a portion, of the C2-C3 rich stream 366, via stream 348, and to produce a C2 rich stream and a C3 rich stream. The C2 separation unit 328 may be a “de-ethanizer column,” such as a distillation column. The C2 rich stream may be provided to the steam cracker unit 308 to increase production of light olefins, such as ethene. The C3 rich stream may be fed to a propane dehydrogenation unit (PDH) 330 to dehydrogenate the C3 rich stream for increased production of, for example, propylene. The C2 separation unit 328 may be in fluid communication with the C3 separation unit 312, the steam cracker unit 308, and the PDH 330.

[0048] The hydrogen supply unit 302 may be configured to produce a hydrogen-rich stream 352. The hydrogen-rich stream 352 may supply hydrogen gas to the LTEP system 326, such as to the hydrocracker feed 364, the Cs rich feed stream 372, and / or Ce rich stream 374 as illustrated by hydrogen rich streams 352, 353, and 354. FIG. 3 illustrates an example of how hydrogen rich streams 352, 353, and 354 may be connected. In other examples, the hydrogen rich streams 352, 353, and 354 may be in a different configuration while maintaining supplying each of the destinations with hydrogen. In some examples, the hydrogen supply unit 302 may provide the hydrogen directly to a heater (not shown) within the C4 reaction unit 306, and / or downstream of the heater, upstream of a reactor vessel within the C4 reaction unit 306, between a plurality of reactor vessels, or directly into a split bed catalyst-type reactor vessel for integration into the process within the C4 reaction unit 306.

[0049] The olefin production system 300 may receive a naphtha stream 370 containing C5-C12 hydrocarbons. In some examples, the naphtha stream 370 may be straight run naphtha or hydrocracked naphtha as discussed in FIG. 1. Furthermore, the naphtha stream 370 may be supplied from various units, such as, CDU 102, DHT 106, and / or HCU 110. The CDU 102, DHT 106, and HCU 110 may be disposed in a refinery area, such as a liquid to chemical (LTC) complex, positioned outside of an area of the naphtha separation unit 314. Stated differently, the naphtha stream 370 may be supplied from units within the refinery that may be positioned far away from the naphtha separation unit 314.24CHEM0019-WO-ORD14

[0050] The naphtha separation unit 314 may be configured to receive one or more naphtha feed streams and an optional aromatic recycle stream from the aromatic-rich stream 378 and to produce a Cs rich feed stream 372, an optional Ce rich stream 374 containing Ce non-aromatic hydrocarbons, and a heavy naphtha stream 382 containing Ce aromatics, such as benzene, and C7+ hydrocarbons. In one example, the naphtha separation unit 314 is fluidly connected to the naphtha stream 370 source units, the C5 rich stream 390 source units, C5 reaction unit 316, an Ce+ reaction unit 320, the separation unit 318, and / or the aromatic processing unit 322. In one example, the C5 rich feed stream 372 may be supplied to the C5 reaction unit 316. The Cs rich feed stream 372 may contain about 10 percent cyclopentane, about 50 percent n-pentane, and about 40 percent 2-m ethylbutane. In another example, the optional Ce rich stream 374 may be supplied to the Ce+ reaction unit 320. The Ce rich stream 374 may contain about 10 percent cyclohexane, about 50 percent n-hexane, and about 40 percent iso-hexanes, such as 2,2-dimethylbutane, 2,3 -dimethylbutane, 2-m ethylpentane, or 3 -methylpentane. In yet another example, the heavy naphtha stream 382 may be supplied to the aromatic processing unit 322. In certain embodiments, the heavy naphtha stream 382 may contain about 90 percent C7+ hydrocarbons.

[0051] The optional Ce rich stream 374 may be produced by the naphtha separation unit 314 in operating examples where the Ce aromatic content of naphtha stream 370 is low, such as up to about 10 percent, up to about 5 percent, such up to or less than 2 percent. In some examples, if the Ce aromatic content of naphtha stream 370 exceeds 5 percent, the Ce rich stream 374 may not be desired as conversion of aromatic components with LTEP catalyst may be low and may result in undesirable build-up in Ce+ reaction unit 320, therefore the naphtha separation unit 314 will be a two-stream producing column in these examples. The Ce aromatic content of naphtha stream 370 may be variable and dependent on the source. In the examples where the Ce rich stream 374 is not produced by the naphtha separation unit 314, the Ce+ reaction unit 320 may be configured to receive the Ce stream 386 from the Ce aromatic saturation unit 324 and a recycle raffinate stream 398 rich in non-aromatic Ce+ hydrocarbons.

[0052] The C4 reaction unit 306 may be configured to receive the hydrocracker feed 364, and a C4 rich recycle stream 394, and to produce an intermediate stream 368 containing substantially ethane and propane. The C4 reaction unit 306 contains a BUTEP process similar to the process found in US. Patent 10,899,979, incorporated herein by reference. In some examples, the C4 reaction unit 306 may be a hydrocracking process that, through a combined mechanism of cracking, isomerization, oligomerization, hydrogenolysis, and hydrogenation / dehydrogenation, produces a final product mixture containing methane, ethane, and propane, via the intermediate stream 368. The catalyst may be equivalent to those24CHEM0019-WO-ORD15discussed in FIG. 2. In one example, hydrogenation metal loading of the catalyst can range from 0.05 weight percent to about 1 weight percent. The C4 reaction unit 306 may be configured to convert at least about 82 percent conversion of the hydrocracker feed 364. In other examples, a reaction vessel within the C4 reaction unit 306 reacts the hydrocracker feed 364 in the presence of the hydrogen provided by the hydrogen-rich stream 352 to produce ethane and propane. In certain embodiments, the C4 reaction unit 306 can be a single reactor vessel or a series of multiple reactor vessels. In some examples, the series of multiple reactor vessels have about four or less reactors in series. The C4 reaction unit 306 may operate at a temperature range of about 350 degrees Celsius to about 500 degrees Celsius, such as about 465 degrees Celsius at a pressure of about 50 psig to about 350 psig, such as about 100 psig, as previously mentioned. In a particular example, the intermediate stream produced by the C4 reaction unit 306 may contain about 22 percent methane, about 70 percent ethane, and about 8 percent of a mixture of benzene, toluene, and dimethylbenzene. In further examples, a side product of the C4 reaction unit 306 may be methane. The methane gas produced from the reaction vessel may be separated via optional stream 371 within the C4 reaction unit 306 and directed to the methane unit 309 for collection. In other examples, the methane gas may be separated downstream of the C4 reaction unit 306, such as from the hydrocracked stream 356 produced from separation unit 318, or from the resulting product stream, such as product stream 310, produced from the steam cracker unit 208, as shown by optional streams 373, or 375, respectively. In certain embodiments, the methane unit 309 may be positioned within the separation unit 318 to receive recovered methane from each effluent streams from the reactor units combined. In some examples, methane gas is not provided to the steam cracker as methane may serve as a fuel gas for other units. For example, the methane may be separated by using a demethanizer (not shown).

[0053] The Cs reaction unit 316 may be configured to receive and crack the C5 rich feed stream 372 and Cs rich recycle stream 396, and to produce a second intermediate stream 392 containing at least ethane, and, in some examples, propane. In some examples, the second intermediate stream 392 may further contain aromatics in addition to the ethane and propane. In one example, the second intermediate stream 392 may contain about 6 percent methane, about 20 percent ethane, and about 74 percent propane. In some examples, the Cs reaction unit 316 may be fluidly connected to the hydrogen supply unit 302, the separation unit 318, the C4 reaction unit 306, the Ce+ reaction unit 320, and the naphtha separation unit 314. The Cs reaction unit 316 may be further fluidly connected to a pygas hydrotreating (PHT) unit (not shown). In that example, the Cs rich feed stream 372 may be mixed with the Cs rich stream 390 sourced from the PHT unit. The Cs rich stream 390 may contain about 50 percent cyclopentane, about 40 percent24CHEM0019-WO-ORD16n-pentane, and about 10 percent 2-methylbutane. In yet another example, the Cs reaction unit 316 may be configured to receive and crack the Cs rich stream 390 without the presence of the Cs rich feed stream 372 from the naphtha separation unit 314.

[0054] The Cs reaction unit 316 may be a unit similar to the C4 reaction unit 206 in which the BUTEP technology within utilizes a zeolite catalyst, present in a reaction vessel within the reaction unit, to initiate a mechanism in the production of, for example, propane through P-scission. Similarly, in certain embodiments, the Cs reaction unit 316 can be a single reactor vessel or a series of multiple reactor vessels. In some examples, the series of multiple reactor vessels have about four or less reactors in series. In some examples, the catalyst may be equivalent to the C4 reaction unit 306 catalyst. The Cs reaction unit 316 may be configured to obtain up at least about 98 percent conversion of the Cs rich feed stream 372. In some examples, the reaction unit may use a flowrate that results in a weight hourly space velocity range of about 1 per hour to about 10 per hour, such as about 6 per hour. In one example, the Cs reaction unit 316 may operate at a temperature range of about 350 degrees Celsius to about 500 degrees Celsius, such as about 395 degrees Celsius. The Cs reaction unit 316 may produce the desired second intermediate stream 392 containing ethane, propane, and aromatics, such as “BTX” (benzene, toluene, or xylene).

[0055] The Ce+ reaction unit 320 may be configured to receive and crack the optional Ce rich stream 374, the Ce stream 386, and / or the recycle raffinate stream 398 in a presence of hydrogen to produce a third intermediate stream 376 containing at least ethane and, in some examples, propane. In certain embodiments, the Ce reaction unit 320 can be a single reactor vessel or a series of multiple reactor vessels. In some examples, the series of multiple reactor vessels have about four or less reactors in series. In some examples, the catalyst may be equivalent to the C4 reaction unit 306 and Cs reaction unit 316 catalyst. The produced third intermediate stream 376 may contain aromatics in addition to the ethane and propane. The Ce+ reaction unit 320 may be in fluid connection with the naphtha separation unit 314, the hydrogen supply unit 302, the Cs reaction unit 316, the C4 reaction unit 306, the Ce aromatic saturation unit 324, the aromatic processing unit 322, and the separation unit 318. The third intermediate stream 376 may be supplied to the separation unit 318.

[0056] The separation unit 318 may be configured to receive and separate unconverted C4, Cs, and aromatics hydrocarbons from produced intermediate streams, from the associated reaction units and to produce a hydrocracked stream 356 containing substantially ethane and propane, the C4 rich stream 394 recycled back to C4 reaction section, the Cs rich recycle stream 396 recycled back to Cs reaction section, and an aromatic-rich stream 378. The separation unit 318 may be in fluid communication with the C424CHEM0019-WO-ORD17reaction unit 306, the Cs reaction unit 316, the Ce+ reaction unit 320, the naphtha separation unit 314, and the steam cracker unit 308. In some examples, the separation unit 318 may contain a separation vessel, such as a knock-out drum to separate the received intermediate streams by density or pressure differential, such as flashing, one or more distillation columns, such as depropanizer, debutanizer, and depentanizer columns, or a combination of flash drums and distillation columns. The hydrocracked stream 356 may be directly supplied to the steam cracker unit 308 or may be combined with the C2-C3 rich stream 366. The aromatic-rich stream 378 may be supplied to the naphtha separation unit 314 and / or the aromatic processing unit 322. The aromatic-rich stream 378 may have at least two optional pathways. For example, the aromatic-rich stream 378 may be fed to the naphtha separation unit 314 to further remove any residual entrained light hydrocarbons through the Cs rich feed stream 372 and optionally, through the Ce rich stream 374. In another example, the aromatic-rich stream 378 may be directed to the aromatic processing unit 322. In yet another example, the aromatic-rich stream 378 may be actively controlled to provide a split flow of the aromatic-rich stream 378 to the naphtha separation unit 314 and the aromatic processing unit 322 via stream 380. The stream 380 may be mixed with the heavy naphtha stream 382 prior to the entry into the aromatic processing unit 322.

[0057] The aromatic processing unit 322 may be in fluid communication with the Ce+ reaction unit 320, the naphtha separation unit 314, or the separation unit 318. The aromatic processing unit 322 may be configured to receive the heavy naphtha stream 382, and / or stream 380, and to produce the recycle raffinate stream 398, and benzene and dimethylbenzene via stream 388. The aromatic processing unit 322 may include an aromatization unit (not shown) and an aromatic separation unit (not shown). The nonaromatic Ce+ hydrocarbons may be recycled back to Ce+ reaction unit 320 via the recycle raffinate stream 398. The recycle raffinate stream 398 may contain about 95 percent of non-aromatic Ce+ hydrocarbons and residual aromatic compounds.

[0058] The Ce aromatic saturation unit 324 may be in fluid communication with the Ce+ reaction unit 320 and configured to treat a Ce aromatic feed stream 384 to produce a Ce stream 386 containing substantially Ce naphthenes and paraffins. In some examples, the Ce stream 386 may be mixed with the optional Ce rich stream 374 from the naphtha separation unit 314 prior to entry to the Ce+ reaction unit 320. Similar to the example illustrated in FIG. 2, the Ce aromatic saturation unit 324 may contain a partial ring opening section or a full ring opening section. The ring opening section within the Ce aromatic saturation unit 324 may break the cyclohexane rings to produce Ce paraffins. In those examples, the Ce stream 386 may contain about 60 percent Ce paraffins and about 40 percent cyclohexane. The Ce paraffins24CHEM0019-WO-ORD18may be mixed with Ce rich stream 374 via the Ce stream 386. In some examples, the Ce aromatic saturation unit 324 may not require a ring opening section and directly feeds Ce naphthenes, such as cyclohexane, to the Ce+ reaction unit 320. In those examples, the stream 386 may contain about 10 percent Ce paraffins and 90 percent naphthenes, such as cyclohexane.

[0059] The C4 reaction unit 306, the C5 reaction unit 316, and the Ce+ reaction unit 320 may be in fluid communication with each other such that the units may be integrated in series, in parallel, or in a combination of series and parallel. For example, while the C4 reaction unit 306 may be possible to condition all of the mixed feeds previously discussed in a single reactor train with multiple reactor vessels, or in parallel reactor vessels, the separation of C4 reaction unit 306, the C5 reaction unit 316, and the Ce+ reaction unit 320 may be beneficial to process the separated streams to increase ethane and propane production as each reaction unit may operate with different conditions to individually increase ethane and propane production while reducing methane production simultaneously. In one example, the C4 reaction unit 306, the C5 reaction unit 316, and the Ce+ reaction unit 320 may be operated in series in which the Ce+ reaction unit 320 partially feeds the C5 reaction unit 316, or partially feeds the C4 reaction unit 306, and in which the C5 reaction unit 316 feeds the C4 reaction unit 306. In other examples, the C4 reaction unit 306, the C5 reaction unit 316, and the Ce+ reaction unit 320 may be integrated to share heat recoveries and / or partial feeds within each of the reaction units. In other examples, the C4 reaction unit 306, the C5 reaction unit 316, and the Ce+ reaction unit 320 may be integrated to share hydrogen rich gas within each of the reaction units. In still other examples, the C4 reaction unit 306, the C5 reaction unit 316, and the Ce+ reaction unit 320 may be independent reaction trains that do not share partial streams, nor feed each other thereby to each provide an intermediate stream to feed the separation unit 318. Therefore, the reaction units may be advantageously oriented and operated to increase ethane and propane production, among other benefits.

[0060] The steam cracker unit 308 may be in fluid communication with the separation unit 318, the C3 separation unit 312, and optionally the C2 separation unit 328. In some examples, the steam cracker unit 308 may be configured to receive the hydrocracked stream 356, and the C2-C3 rich stream 366 (or the C2 rich stream from the C2 separation unit 328), and to produce a product stream 310 that contains light olefins, including ethene and propene. The LTEP system 326 advantageously extends the usage of the catalyst in the reaction units to increase the production of ethane and propane that results in increased production of light olefins, such as ethene and propene by the steam cracker unit 308.24CHEM0019-WO-ORD19

[0061] FIG. 4 is a flow chart of a method 400 in which light olefin production may be increased by separating C2-C4 feed streams with a C2 separation unit and by hydrocracking to feed a steam cracker unit, according to one example. The method 400 includes blocks 402, 404, 406, 408, 410, and 412. The following method 400 incorporates FIG. 2 embodiments and will reference FIG. 2 numerals for ease of explanation. However, the method 400 is not limited to the examples of FIG. 2. Furthermore, the aforementioned blocks of method 400 do not need to be performed in sequence but rather may be performed as optional block operations or nonsequential block operations. In some examples, some of the blocks of method 400 are bypassed or skipped as the source fluid may be unavailable.

[0062] The method 400 provides an increased production of light olefins. In specific, the embodiment of FIG. 2 provides an increased production of light olefins, such as ethene by separation C2-C4 feed streams with a C2 separation unit 228 and hydrocracking within LTEP system 226 to feed a steam cracker unit 208.

[0063] The method 400 begins at block 402, by separating a C2-C4 feed stream 262 within the C2 separation unit 228 to produce a C3-C4 stream 264 and a C2-rich stream 266. The C3-C4 stream 264 may be configured to feed the reaction section of C4 reaction unit of the LTEP system 226. The C2-rich stream 266 may be configured to feed the steam cracker unit 208.

[0064] At block 404, the method 400 combines the C3-C4 stream 264 with a mixed C4 stream 250 containing substantially 2-methylpropane and n-butane to produce a mixed C3-C4 stream to collectively feed with LTEP system 226. In some examples, the mixed C4 stream 250 may be supplied from a total hydrogenation unit. In some examples, the mixed C4 stream 250 and the mixed C3-C4 stream may each independently feed the C4 reaction unit of the LTEP system 226.

[0065] At block 406, the method 400 catalytically cracks the mixed C3-C4 stream in a presence of hydrogen, within the reaction section of LTEP system 226, to produce an intermediate stream containing substantially ethane. In some examples the intermediate stream contains aromatics. The intermediate stream may be configured to feed a separation unit 218 within the LTEP system 226.

[0066] At block 408, the method 400 separates aromatics from the intermediate stream, within a separation section of the LTEP system 226, to produce the aromatic-rich stream 278 and the hydrocracked stream 256. In the embodiment of FIG. 2, the hydrocracked stream 256 contains substantially ethane to further produce an increased yield of ethene from the steam cracker unit 208. In some examples, the C4 rich recycle stream 294 may be recycled to the C4 reaction unit 206 for further production of ethane from the LTEP system 226 as illustrated by the recycle stream in FIG. 4.24CHEM0019-WO-ORD20

[0067] The method 400 continues at block 410 by supplying the hydrocracked stream 256 to a steam cracker unit 208, thereby to produce ethene. The steam cracker unit 208 produces the desired light olefins, such as ethene, from ethane within the hydrocracked stream 256.

[0068] At block 412, the method 400 includes supplying the aromatic-rich stream 278, from block 408, to an aromatic processing unit 222, thereby to produce benzene and dimethylbenzene via stream 288. The recycle raffinate stream 298 containing non-aromatics may be recycled back to LTEP system 226 to further increase ethane content within the hydrocracked stream 256.

[0069] Units and streams discussed in the method 400, but not illustrated in FIG. 2, may have similar units and streams illustrated in FIG. 3. Unless otherwise noted, the descriptions and examples discussed in FIG. 3, apply equally to the LTEP system 226, thereby to disclose details within the LTEP system 226 when not illustrated.

[0070] FIG. 5 is a flow chart of a method 500 in which light olefin production may be increased by separating C2-C4 feed streams with a C3 separation unit and by hydrocracking to feed a steam cracker unit, according to one example. The method 500 includes blocks 502, 504, 506, 508, 510, 512, and 514. The following method 500 incorporates FIG. 3 embodiments and will reference FIG. 3 numerals for ease of explanation. However, the method 500 is not limited to the examples of FIG. 3. Furthermore, the aforementioned blocks of method 500 do not need to be performed in sequence but rather may be performed as optional block operations or nonsequential block operations. In some examples, some of the blocks of method 500 are bypassed or skipped as the source fluid may be unavailable.

[0071] The method 500 provides an increased production of light olefins. In specific, the embodiment of FIG. 3 provides an increased production of light olefins, such as ethene and propene by separation C2-C4 feed streams with a C3 separation unit 312, and optionally with a C2 separation unit 328, and hydrocracking within LTEP system 326 to feed a steam cracker unit 308.

[0072] The method 500 begins at block 502, by separating a C2-C4 feed stream 362 within the C3 separation unit 312 to produce a hydrocracker feed 364 rich in butanes and a C2-C3 rich stream 366. The hydrocracker feed 364 may be configured to feed the C4 reaction unit 306 of the LTEP system 326. The C2-C3 rich stream 366 may be configured to feed the steam cracker unit 308 or optionally feed to the C2 separation unit 328 which then feed a C2 rich stream to the steam cracker unit 308.

[0073] At block 504, the method 500 combines the hydrocracker feed 364 with a mixed C4 stream 350 containing substantially 2-methylpropane and n-butane to collectively feed with LTEP system 326. In some examples, the mixed C4 stream 350 may be supplied from a total hydrogenation unit. In some24CHEM0019-WO-ORD21examples, the mixed C4 stream 350 and the hydrocracker feed 364 may each independently feed the C4 reaction unit 306 of the LTEP system 326.

[0074] At block 506, the method 500 catalytically cracks the mixed C4 stream in a presence of hydrogen, within the C4 reaction unit 306, to produce an intermediate stream containing substantially ethane and propane. In some examples the intermediate stream contains aromatics. The intermediate stream may be configured to feed a separation unit 318.

[0075] At block 508, the method 500 separates aromatics from the intermediate stream, within a separation section of the LTEP system 326, to produce the aromatic-rich stream 378 and the hydrocracked stream 356. In the embodiment of FIG. 3, the hydrocracked stream 356 contains substantially ethane and propane to further produce an increased yield of ethene and propene from the steam cracker unit 308. In some examples, the C4 rich recycle stream 394 may be recycled to the C4 reaction unit 306 for further production of ethane and propane from the LTEP system 326 as illustrated by the recycle stream in FIG.5.

[0076] The method 500 continues at block 510 by supplying the hydrocracked stream 356 and the C2-C3 stream (or the C2 rich stream) to a steam cracker unit 308, thereby to produce ethene and propene. As previously discussed, the steam cracker unit 308 produces the desired light olefins, such as ethene and propene, from ethane and propane within the hydrocracked stream 356.

[0077] At block 512, the method 500 includes supplying the aromatic-rich stream 378, from block 508, to an aromatic processing unit 322, thereby to produce benzene and dimethylbenzene via stream 388.

[0078] At block 514, the method 500 may alternatively, or partially process the C2-C3 rich stream into a least a C2 rich stream in further refinement of desired products in the steam cracker unit 308. Block 514 may be an optional pathway for the C2-C3 rich stream.

[0079] FIG. 6 is a flow chart of a method 600 in which light olefin production may be increased by separating and hydrocracking heavy hydrocarbons feed streams to feed a steam cracker unit, according to one example. The method 600 includes blocks 602, 604, 606, 608, 610, 612, 614, 616, 618, and 620. The following method 600 incorporates FIG. 3 embodiments and will reference FIG. 3 numerals for ease of explanation. However, the method 600 is not limited to the examples of FIG. 3. Furthermore, the aforementioned blocks of method 600 do not need to be performed in sequence but rather may be performed as optional block operations or nonsequential block operations. In some examples, some of the blocks of method 600 are bypassed or skipped as the source fluid may be unavailable.24CHEM0019-WO-ORD22

[0080] As previously mentioned, the method 600 provides an increased production of light olefins. In specific, the embodiment of FIG. 3 provides an increased production of light olefins, such as ethene and propene by separation and hydrocracking heavy hydrocarbons feed streams to a steam cracker unit 308.

[0081] The method 600 includes block 602 by separating a naphtha stream 370 containing Cs+ hydrocarbons, such as C5-C12 hydrocarbons, to produce a C5 rich feed stream 372, a Cerich stream 374, and a heavy naphtha stream 382. As previously discussed, the naphtha stream 370 may be sourced from various units, such as, the CDU 102, DHT 106, and HCU 110, as shown in FIG. 1. The C5 rich feed stream 372 may be configured to feed the C5 reaction unit 316. The optional Cerich stream 374 may be configured to feed the Ce+ reaction unit 320 in examples when the naphtha stream 370 contains a low content of aromatics. The heavy naphtha stream 382 may be configured to feed the aromatic processing unit 322.

[0082] At block 604, the method 600 may mix the C5 rich feed stream 372 with a C5 rich stream 390. In some examples, the C5 rich stream 390 may be supplied from the PHT unit. In some examples, the C5 rich stream 390 makes a portion of the C5 rich feed stream 372. In other examples, the C5 rich stream 390 may be configured to feed the C5 reaction unit 316 independent of the C5 rich feed stream 372.

[0083] At block 606, the method 600 catalytically cracks the C5 rich feed stream 372 in a presence of hydrogen, within the C5 reaction unit 316, to produce an intermediate stream 392 containing at least ethane. In some embodiments, the intermediate stream 392 contains ethane and propane. The intermediate stream 392 may be configured to feed the separation unit 318.

[0084] The method 600 continues at block 608 by separating aromatics from the second intermediate stream 392, within the separation unit 318, to produce the C5 rich recycle stream 396, aromatic-rich stream 378, and the hydrocracked stream 356. In some examples, as previously discussed, the C5 rich recycle stream 396 may be recycled to the C5 reaction unit 316 for further production of ethane and propane from the LTEP system 326 as illustrated by the recycle stream in FIG. 6 connecting block 608 to block 606.

[0085] The method 600 continues at block 618, by supplying the hydrocracked stream 356 to a steam cracker unit 308, thereby to produce ethene and propene. As previously discussed, the steam cracker unit 308 produces the desired light olefins, such as ethene and propene, from the ethane and propane within the hydrocracked stream 356.

[0086] At block 620, the method 600 includes supplying the aromatic-rich stream 378, from block 608 and / or block 616, and the heavy naphtha stream 382, from block 602, to an aromatic processing unit 322, thereby to produce benzene and dimethylbenzene via stream 388. As previously discussed, the aromatic-rich stream 378 may be fed to the naphtha separation unit 314 or optionally mixed with the heavy naphtha24CHEM0019-WO-ORD23stream 382 flowing to the aromatic processing unit 322, as illustrated in FIG. 3. Furthermore, the aromatic processing unit 322 may produce the recycle raffinate stream 398 rich in non-aromatic Ce+ hydrocarbons for recycle back to the Ce+ reaction unit 320 as illustrated by the recycle stream in FIG. 6 connecting block 620 to block 614.

[0087] The method 600 also includes, at block 610, treating a Ce aromatic feed stream 384 within the Ce aromatic saturation unit 324 to produce a Ce stream 386 containing substantially Ce paraffins and naphthenes.

[0088] The method 600 continues at block 612 by mixing the Ce stream 386 with the Cerich stream 374, from block 602, such that both streams collectively feed the Ce+ reaction unit 320. In some examples, the Ce stream 386 with the Ce rich stream 374 may independently feed the Ce+ reaction unit 320 within the LTEP system 326. As previously discussed, in some examples, the naphtha separation unit 314 does not produce the Cerich stream 374.

[0089] The method 600 continues at block 614 by catalytically cracking the Ce rich stream 374, and / or the Ce stream 386, in a presence of hydrogen within the Ce+ reaction unit 320 to produce an intermediate stream 376, also referred to a second intermediate stream 376 with respect to intermediate stream 392 in block 606. In some examples, the second intermediate stream 376 is supplied to the separation unit 318.

[0090] At block 616, the method 600 separates aromatics from the second intermediate stream 376 within the separation unit 318 to produce the aromatic-rich stream 378 and the hydrocracked stream 356. The hydrocracked stream 356 produced from block 616 may be supplied to the steam cracker unit 308, in block 620, thereby to produce ethene and propene. The aromatic-rich stream 378 produced from block 616 may be supplied to the aromatic processing unit 322, thereby to produce benzene and dimethylbenzene. As previously discussed, the recycle raffinate stream 398 containing non-aromatics may be recycled back to LTEP system 326, as illustrated by the recycle stream connecting block 620 to block 614.

[0091] Other objects, features, and advantages of the disclosure will become apparent from the foregoing figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific examples of the disclosure, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from the detailed description. In further examples, features from specific examples may be combined with features from other examples. For example, features from one example may be combined with features24CHEM0019-WO-ORD24from any of the other examples. In further examples, additional features may be added to the specific examples described herein.

Claims

24CHEM0019-WO-ORD25CLAIMSWhat is claimed is:

1. A method of producing olefins, the method comprising:separating a naphtha feed stream containing C5-C12 hydrocarbons to produce a C5 rich feed stream and a heavy naphtha stream;catalytically cracking the C5 rich feed stream in a presence of hydrogen to produce a first intermediate stream containing at least ethane;separating aromatics from the first intermediate stream to produce an aromatic-rich stream and a hydrocracked stream; andsupplying the hydrocracked stream to a steam cracker, thereby to produce at least ethene.

2. The method of claim 1, further comprising:separating a C2-C4 feed stream to produce a C2 stream and a C3-C4 stream;catalytically cracking the C3-C4 stream in a presence of hydrogen to produce a second intermediate stream;separating aromatics from the second intermediate stream to produce the aromatic-rich stream and the hydrocracked stream; andsupplying the C2 stream and the hydrocracked stream to the steam cracker, thereby to produce at least ethene.

3. A method of claim 2, the method further comprising:recycling unconverted C4 hydrocarbons from the second intermediate stream to be mixed with the C3-C4 stream.

4. A method of claim 1, further comprising:separating a C2-C4 feed stream to produce a C2-C3 stream and a hydrocracker feed stream, the hydrocracker feed stream containing butane;optionally separating the C2-C3 stream to produce a C2 rich stream and a C3 rich stream, the C3 rich stream to be supplied to a propane dehydrogenation unit, thereby to produce propylene; catalytically cracking the hydrocracker feed stream in a presence of hydrogen to produce a second intermediate stream containing substantially ethane and propane;24CHEM0019-WO-ORD26separating aromatics from the second intermediate stream to produce the aromatic-rich stream and the hydrocracked stream; andsupplying the C2-C3 stream, or the C2 rich stream via the optional separation of the C2-C3 stream, in addition to the hydrocracked stream to the steam cracker, thereby to produce ethene and propene.

5. A method of claim 4, the method further comprising:combining a mixed C4 stream containing substantially 2-methylpropane and n-butane with the hydrocracker feed stream;mixing a Cs rich stream with the Cs rich feed stream, and wherein the Cs rich stream is supplied from a pygas hydrotreating unit; andsupplying the aromatic-rich stream and the heavy naphtha stream to an aromatic processing unit, thereby to produce benzene and dimethylbenzene.

6. A method of claim 1, the method further comprising:further separating the naphtha feed stream to produce a Ce rich stream in addition to the Cs rich feed stream and the heavy naphtha stream;catalytically cracking the Ce rich stream in a presence of hydrogen to produce a third intermediate stream; andseparating aromatics from the third intermediate stream to produce the aromatic-rich stream and the hydrocracked stream.

7. A method of claim 1, the method further comprising:treating a Ce aromatic feed to produce a Ce stream containing substantially Ce paraffins and Ce naphthenes;catalytically cracking the Ce stream in a presence of hydrogen to produce a third intermediate stream; andseparating aromatics from the third intermediate stream to produce the aromatic-rich stream and the hydrocracked stream.

8. A system comprising:a naphtha separation unit configured to receive one or more naphtha feed streams and to produce a Cs rich feed stream and a heavy naphtha stream;24CHEM0019-WO-ORD27an aromatic processing unit in fluid communication with the naphtha separation unit and configured to receive the heavy naphtha stream and to produce benzene and dimethylbenzene; a Cs reaction unit in fluid communication with the naphtha separation unit and configured to receive and crack the Cs rich feed stream and to produce a first intermediate stream containing ethane and aromatics;a separation unit in fluid communication with the Cs reaction unit and the naphtha separation unit and configured to separate aromatics from the first intermediate stream and to produce a hydrocracked stream containing ethane and an aromatic-rich stream; anda steam cracker unit in fluid communication with the separation unit and configured to receive the hydrocracked stream and to produce at least ethene.

9. The system of claim 8, further comprising:the naphtha separation unit further configured to produce a Ce rich stream; anda Ce+ reaction unit in fluid communication with the naphtha separation unit and the separation unit and configured to receive and crack the Ce rich stream in a presence of hydrogen to produce a second intermediate stream containing ethane and aromatics fed to the separation unit to produce the hydrocracked stream and the aromatic-rich stream.

10. The system of claim 9, further comprising:a Ce aromatic saturation unit in fluid communication with the Ce+ reaction unit and configured to treat a Ce aromatic feed to produce a Ce stream containing substantially Ce paraffins and Ce naphthenes to be fed to the Ce+ reaction unit.

11. The system of claim 8, further comprising:a C2 separation unit configured to receive a C2-C4 feed stream supplied from one or more of a crude distillation unit, a diesel hydrotreater unit, or a hydrocracker unit and to produce a C2- rich stream containing substantially ethane fed to the steam cracker unit and a C3-C4 stream; anda C4 reaction unit in fluid communication with the C2 separation unit and the separation unit and configured to receive and crack the C3-C4 stream and a mixed C4 stream supplied from a total hydrogenation unit in a presence of hydrogen to produce a third intermediate stream containing24CHEM0019-WO-ORD28ethane and aromatics fed to the separation unit to produce the hydrocracked stream and the aromatic-rich stream.

12. The system of claim 11, further comprising:a methane unit configured to received recovered methane from the separation unit, the hydrocracked stream, or a steam cracker product stream containing produced ethene.

13. The system of claim 9, further comprising:a C3 separation unit configured to receive a C2-C4 feed stream supplied from one or more of a crude distillation unit, a diesel hydrotreater unit, or a hydrocracker unit and to produce a hydrocracker feed containing mixed butanes and to further produce a C2-C3 stream; and a C4 reaction unit in fluid communication with the C3 separation unit and the separation unit and configured to receive and crack the hydrocracker feed in a presence of hydrogen to produce a third intermediate stream containing ethane, propane, and aromatics fed to the separation unit to produce the hydrocracked stream and the aromatic-rich stream.

14. The system of claim 13, further comprising:a C2 separation unit in fluid communication with the C3 separation unit and configured to receive and separate the C2-C3 stream to produce a C2 rich stream and a C3 rich stream;a propane dehydrogenation unit in fluid communication with the C2 separation unit and configured to dehydrogenate the C3 rich stream, thereby to produce propylene; andwherein the steam cracker unit is further configured to receive the C2 rich stream in addition to the hydrocracked stream, thereby to produce ethene.

15. The system of claim 13, wherein the C2-C4 feed stream is supplied from a saturated gas plant in fluid communication with the crude distillation unit, the diesel hydrotreater unit, or the hydrocracker unit and the C3 separation unit, wherein the steam cracker unit is further configured to receive the C2-C3 stream in addition to the hydrocracked stream, thereby to produce ethene and propene, and wherein the C4 reaction unit, the Cs reaction unit, and the Ce+ reaction unit are in fluid communication with each other and configured to be in series such that the Ce+ reaction unit partially feeds the C4 reaction unit or the Cs reaction unit, and the Cs reaction unit partially feeds the C4 reaction unit to share heat recoveries.

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