Methods and systems for enhanced olefin production using separation and hydrocracking heavy hydrocarbons

Abstract

Provided here are methods and systems for enhanced olefin production using separation and hydrocracking heavy hydrocarbons. One such method for producing olefins includes separating a paraffin feed stream containing substantially 2-methylpropane and n-butane to produce a 2-methylpropane-rich stream and a n-butane-rich stream, hydrocracking the 2-methylpropane-rich stream in a presence of hydrogen to produce a hydrocracked product stream containing substantially ethane and propane, and supplying the n-butane-rich stream and the hydrocracked product stream to a steam cracker, thereby to produce ethene and propene.

Description

24CHEM0013 - WO-ORD1METHODS AND SYSTEMS FOR ENHANCED OLEFIN PRODUCTION USING SEPARATION AND 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 using separation and hydrocracking heavy hydrocarbons.BACKGROUND

[0002] 2-Methylpropane has proven to be an inefficient feed to a steam cracker, resulting in lesser ethene and propene yields. Applicant has previously developed technology to crack 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. However, current technology design processes utilized to treat the mixed butane feed necessitate significant amounts of hydrogen, and / or other utilities, leading to increased operational costs and inefficient production of olefins, in particular ethene and propene. Therefore, Applicant has recognized there remains a need to for enhanced and cost-effective processes to produce olefins from current technology design processes.SUMMARY

[0003] Examples set forth herein include methods and systems for enhanced olefin production using separation and hydrocracking heavy hydrocarbons. One such method for producing olefins includes separating a paraffin feed stream containing substantially 2-methylpropane and n-butane to produce a 2-methylpropane-rich stream and a n-butane-rich stream, hydrocracking the 2- methylpropane-rich stream in a presence of hydrogen to produce a hydrocracked product stream containing substantially ethane and propane, and supplying the n-butane-rich stream and the hydrocracked product stream to a steam cracker, thereby to produce ethene and propene.

[0004] In another example, the method further includes separating a C2-C4 feed stream to produce at least a portion of the paraffin feed stream containing substantially 2-methylpropane and n-butane and a C2-C3-rich stream. In yet another example, the method further includes mixing the C2-C3-rich stream and the n-butane-rich stream prior to supplying them to the steam cracker.24CHEM0013 - WO-ORD2

[0005] In another example, a system includes a C4 separation unit configured to receive a paraffin feed stream containing substantially 2-methylpropane and n-butane and to produce a 2- methylpropane-rich stream and a n-butane-rich stream, a hydrocracking unit in fluid communication with the C4 separation unit and configured to receive and crack the 2- methylpropane-rich stream in a presence of hydrogen to produce a hydrocracked product stream containing substantially ethane and propane, and a steam cracker unit in fluid communication with the C4 separation unit and the hydrocracking unit and configured to receive the n-butane-rich stream and the hydrocracked product stream and to produce ethene and propene.

[0006] In another example, a system further includes a C3 separation unit in fluid communication with the C4 separation unit and operable to receive a C2-C4 feed stream and produce C2-C3-rich stream containing substantially ethane and propane and at least a portion of the paraffin feed stream.

[0007] 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

[0008] 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 below24CHEM0013 - WO-ORD3 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.

[0009] FIG. 1 is a schematic representation of a conventional olefin production system using a mixed butane feed to a steam cracker unit, according to an example.

[0010] FIG. 2 is a schematic representation of an olefin production system using a C4 separation unit to feed 2-methylpropane to a hydrocracking unit, according to an example.

[0011] FIG. 3 is a schematic representation of an olefin production system using a C4 separation unit to feed 2-methylpropane to a hydrocracking unit and a C3 separation unit to produce a portion of the feed to the C4 separation unit, according to an example.

[0012] FIG. 4 is an illustration of a method in which C3 and C4 streams are separated to feed the stream cracker unit, according to an example.

[0013] It is contemplated that elements and features of one embodiment may be beneficially incorporated into other embodiments without further recitation.DETAILED DESCRIPTION

[0014] Olefins are used to produce various products including plastics, medicines, and other useful materials. In many refining operations, olefins are maximized to produce increased revenue. Previously, a paraffin stream would be fed directly to the steam cracker. Improvements for increased production of olefins include conditioning of the paraffin stream to produce a better product from the steam cracker. One such technology, referred to as BUTEP below, involves hydrocracking the paraffin stream to produce ethane and propane, a known feed 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.

[0015] In some examples, the paraffin stream contains at least mixed butanes, including 2- methylpropane and n-butane. However, n-butane is an inefficient feed to the current BUTEP technology, resulting in increased operational costs. Current BUTEP technology designs require a significant amount of hydrogen, and other utilities, to hydrocrack the mixed butane paraffin feed to ethane and propane. This leads to increased operational costs and inefficient production of olefins, in particular ethene and propene.24CHEM0013 - WO-ORD4

[0016] Current BUTEP processes involve receiving a mixed butane feed, processing the stream components, and providing an ideal feed of propane and ethane to the stream cracker. However, surprising and unexpected results were obtained by separation of the mixed butane paraffin feed prior to hydrocracking through the BUTEP process resulting in less operational costs and an advantageous increase to the production of the olefins. For example, current BUTEP process utilizes a zeolite catalyst, present in a reaction vessel within a hydrocracking unit, to initiate a mechanism in the production of, for example, propane through P-scission. However, n-butane cannot undergo P-scission initially. The conditioning of n-butane to enable P-scission may necessitate isomerization of the n-butane to 2-methylpropane, dehydrogenation to produce 2- methylprop-l-ene, and further oligomerization to produce a Cs which can then undergo P-scission cracking to a C3 and a Cs. Reactions may further oligomerize the Cs to higher hydrocarbons to repeat the P-scission cycle to further produce C3. Thus, multiple operations may occur prior to obtaining ethane and / or propane from a feed that contains n-butane.

[0017] In the proposed enhancement design, mixed butanes are first sent to a separator to separate at least n-butane and 2-methylpropane. The 2-methylpropane is fed to the BUTEP technology while the n-butane is directly fed to the steam cracker to produce an increased production of propene and ethene while reducing operational costs.

[0018] In another example, C2-C4 gases collected from various units such as, for example, a crude distillation unit, a hydrotreater unit, or another hydrocracker unit, may be routed through a C3 separation unit to produce a C2-C3 stream and C4-rich stream. The C2-C3 stream can be sent to the steam cracker and the C4 stream can be mixed with the paraffin stream to improve the ethene and propene yield from steam cracker.

[0019] Therefore, the present disclosure benefits existing hydrocracking BUTEP processes by enhancing olefin production using separation and hydrocracking heavy hydrocarbons to yield increased olefin production, thereby reducing the cost of catalyst and utilities of the BUTEP process.

[0020] 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 herein24CHEM0013 - WO-ORD5 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.

[0021] 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 a mixture 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 nonlimiting 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 X 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.

[0022] 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 hydrocarbon-based 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 atom containing compounds.

[0023] 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 components24CHEM0013 - WO-ORD6 may be alternatively described as being in fluid communication 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.

[0024] FIG. 1 is a schematic representation of a conventional olefin production system 100 using a mixed butane feed to a steam cracker unit 108. The olefin production system 100 includes various units, such as, a hydrogen supply unit 102, a heating unit 104, a hydrocracking unit 106 (which includes the BUTEP technology), and a steam cracker unit 108. The olefin production system 100 further includes various streams, such as streams 150, 152, 154, and 156.

[0025] The olefin production system 100 is supplied with a paraffin stream 150 containing mixed butanes. The mixed butanes may include at least 2-methylpropane and n-butane. In some examples, the paraffin stream 150 may be supplied by various units. For example, the paraffin stream 150 may be supplied from a total hydrogenation unit, a crude distillation unit, and / or a hydrocracking unit. In some examples, the paraffin stream 150 includes about 30:70 molar percent ratio of 2-methylpropane to n-butane.

[0026] The hydrogen supply unit 102 can be configured to produce a hydrogen-rich stream 152. In some examples, the hydrogen supply unit 102 may be fluidly connected to a total hydrogenation unit, a crude distillation unit, a hydrocracking unit, and / or a heating unit 104. The hydrogen-rich stream 152 supplies the paraffin stream 150 with hydrogen gas. The heating unit 104 may be configured to receive the paraffin stream 150 and the hydrogen-rich stream 152 and to produce a heated hydrocracker feed 154.

[0027] The hydrocracking unit 106 may be configured to receive the heated hydrocracker feed 154 and to produce a hydrocracked stream 156 containing ethane and propane. The hydrocracking unit 106 contains a “butane to ethane and propane” (BUTEP) process similar to the process found in US. Patent 10,899,979. In some examples, the hydrocracking unit 106 can process C3-C12 hydrocarbons, through a combined mechanism of cracking, isomerization, oligomerization, hydrogenolysis, and hydrogenation / dehydrogenation, to produce a final product mixture of methane ethane and propane. In some examples, the hydrocracking unit 106 may include a reaction vessel (not shown) with approximate dimensions of about 2.59 meters (m) by about 8.84 m. The24CHEM0013 - WO-ORD7 reaction vessel may contain a catalyst on a fixed bed, or similar support. The catalyst may be a zeolite, such as ZSM-5 containing about 5 weight percent (wt. %) platinum. In other examples, the reaction vessel of the hydrocracking unit 106 is configured for the reaction of the paraffin stream 150 in the presence of the hydrogen from the hydrogen-rich stream 152 to produce ethane and propane. The steam cracker unit 108 can be configured to receive the hydrocracked stream 156 and to produce light olefins, including ethene and propene.

[0028] FIG. 2 is a schematic representation of an olefin production system using a C4 separation unit to supply 2-methylpropane to a hydrocracking unit, according to an example. The enhanced olefin production system 200 includes various units, such as a C4 separation unit 210, a hydrogen supply unit 202, a heating unit 204, a hydrocracking unit 206, and a steam cracker unit 208. The olefin production system 200 further includes various streams such as streams 250, 252, 254, 256, 258, 260, and optional streams 270, 272, and / or 274. The olefin production system 200 is supplied with a paraffin stream 250 containing mixed butanes. The mixed butanes include at least 2- methylpropane and n-butane. In some examples, the paraffin stream 250 may be supplied by various units. For example, the paraffin stream 250 may be supplied from a total hydrogenation unit (not shown) that is fluidly connected to the C4 separation unit 210. In one example, the paraffin stream 250 includes about 50:50 molar percent ratio of 2-methylpropane to n-butane. However, to facilitate comparison to the conventional olefin production system 100 of FIG. 1, the following example of the paraffin stream 250 includes about 30:70 molar percent ratio of 2-methylpropane to n-butane.

[0029] The C4 separation unit 210 may be configured to receive the paraffin stream 250 and to produce a 2-methylpropane-rich stream 258 and a n-butane-rich stream 260. In one example, the 2-methylpropane-rich stream 258 includes about 95.3 mole percent (mol %) of 2-methylpropane. In yet another example, the 2-methylpropane-rich stream 258 includes at least about 90 wt. % of 2-methylpropane. In another example, the n-butane-rich stream 260 may include about 98 mol % of n-butane. In yet another example, the n-butane-rich stream 260 includes at least about 90 wt. % of n-butane. In certain embodiments, the C4 separation unit 210 can be a “deisobutanizer” column, such as a distillation column. The C4 separation unit 210 may be fluidly connected to at least the hydrogen supply unit 202, the heating unit 204, and the steam cracker unit 208. In some examples, the C4 separation unit 210 may include a reboiler (not shown) to energize the received fluid within24CHEM0013 - WO-ORD8 the unit. The reboiler may use about 20.9 MMkcal / hr. In some examples, reboiler may be energized by low pressure steam or a heat pump compressor to meet the heat desired, or heat requirement, of a distillation column, for example. In one example, the flowrate of the 2-methylpropane-rich stream 258 may be about 20.16 TPH, about one third the flowrate from the example of FIG. 1. The n-butane-rich stream 260 may flow to the steam cracker unit 208. In some examples, the distillation column within the C4 separation unit 210 may operate with a pressure of about 3 bar-g to about 9 bar-g, such as about 5 bar-g to about 7 bar-g. In one example, the distillation column has 80-90 conventional trays. The distillation column may be constructed from killed carbon steel, or the like, suitable to handle paraffins without degradation. The distillation column may further be rated at 150 pound flange class.

[0030] The hydrogen supply unit 202 may be configured to produce a hydrogen-rich stream 252. The hydrogen supply unit 202 may be fluidly connected to the C4 separation unit 210, and / or the heating unit 204. In some examples, the hydrogen supply unit 202 provides about 0.39 TPH flowrate of hydrogen gas through the hydrogen-rich stream 252 to the 2-methylpropane-rich stream 258. The combined flowrate of the hydrogen-rich stream 252 and the 2-methylpropane-rich stream 258 may be about 20.55 TPH to be fed to the heating unit 204. In other examples, while not illustrated, the hydrogen supply unit 202 may provide the hydrogen-rich stream 252 upstream of the heater, as discussed above, and / or downstream of the heater, upstream of a reactor vessel within the hydrocracking unit 206, between a plurality of reactor vessels, or directly into a split bed catalyst-type reactor vessel for integration into the process.

[0031] The heating unit 204 may be configured to receive the hydrogen-rich stream 252 and the 2-methylpropane-rich stream 258 and to produce a heated hydrocracker feed 254. A conventional mixed butane feed stream may be heated to about 370 degrees Celsius. The heating unit 204 may heat the hydrogen-rich stream 252 and the 2-methylpropane-rich stream 258 mixture to about 375 degrees Celsius to 425 degrees Celsius. Therefore, it is expected that the hydrocracking unit 206 operating temperature may be required to increase by about 5 degrees Celsius to about 50 degrees Celsius, such as about 5 degrees Celsius to about 10 degrees Celsius, or such as about 15 degrees Celsius to about 30 degrees Celsius, compared to a conventional mixed butane feed stream, to compensate for a heat of reaction associated with residual n-butane to 2-methylpropane reaction. A conventional mixed butane feed stream to the hydrocracker unit undergoes some extent of24CHEM0013 - WO-ORD9 isomerization of n-butane to 2-methylpropane at an upper portion of hydrocracking unit 206, which is an exothermic reaction that generates heat. This exothermic reaction will not be present with hydrocracking of the 2-methylpropane-rich stream 258. Therefore, the heating unit 204 heats the hydrogen-rich stream 252 and the 2-methylpropane-rich stream 258 by about 5 to about 50 degrees Celsius to achieve the same level of total C4 conversion as a conventional mixed butane feed stream to the hydrocracker unit. In some examples, the heating unit 204 may provide a duty of about 0.77 MMKcal / hr to heat the streams.

[0032] The hydrocracking unit 206 may be configured to receive the heated hydrocracker feed 254 and to produce a hydrocracked stream 256 containing ethane and propane. In some examples, the hydrocracking unit 206 may include a reaction vessel (not shown) with approximate dimensions of about 1.42 m by about 8.84 m. The reaction vessel may contain a catalyst. The catalyst may be a zeolite such as ZSM-5 containing about 5 wt. % platinum. In some examples, the reaction vessel may use the catalyst at a rate of 22.1 tons per 3 reaction cycles. In other examples, the reaction vessel within the hydrocracking unit 206 reacts the paraffin stream 250 in the presence of the hydrogen provided by the hydrogen-rich stream 252 to produce ethane and propane. In further examples, a side product of the hydrocracking unit 206 may be methane. In some examples, the methane gas produced from the reaction vessel may be separated via optional stream 270 within the hydrocracking unit 206. In some examples, the methane gas may be separated downstream of the hydrocracking unit 206, such as from the hydrocracked stream 256, and / or from the resulting product produced from the steam cracker unit 208, as shown by optional streams 272, and / or 274 respectively. It is not desirable to provide the steam cracker with methane gas as methane remains unconverted in a steam cracker and reduces the utilization rate of the steam cracker by occupying space that increases operational expenses without resulting in any useful product yield. Instead, the methane gas may serve as a fuel gas for other units. For example, the methane may be separated by using a demethanizer (not shown). In another example, methane may be captured by directing a small percentage of the hydrocracked stream 256 to a furnace (not shown) following a capture of ethane and / or propane. In one example, the carbon loss resulting from the separation of methane through either optional streams 270, 272, and / or 274, may be less than or equal to about 1 percent of the carbon within the heated hydrocracker feed 254 or the 2- m ethylpropane-rich stream 258.24CHEM0013 - WO-ORD10

[0033] The steam cracker unit 208 may be configured to receive the hydrocracked stream 256 and the n-butane-rich stream 260 and to produce a product stream (not shown) that contains light olefins, including ethene and propene. In some examples, the hydrocracked stream 256 and the n- butane-rich stream 260 may be fed separately to the steam cracker unit 208.

[0034] The configuration of FIG. 1 and FIG. 2 are compared in Table 1. The table below illustrates the yields that correlate to the system 100 and the system 200 as discussed above. Various values and calculations may be obtained and / or performed from the combination of information presented in the table below.Table 1. Comparison of yield according to an embodiment.

[0035] Table 1 compares two operational conditions which may be used to compare the system 100 and the system 200 each using a 30:70 molar percent ratio of 2-methylpropane to n-butane, as discussed above. For example, Table 1 illustrates a total olefin increased conversion of at least 2.1% in system 200 of FIG. 2 over the conventional system 100 of FIG. 1. However, in addition to product increase, other benefits may be further present. For example, suppling n-butane to the hydrocracker unit will reduce the amount of methane produced while further resulting in the higher yield of desired olefin products. In another example, the paraffin stream 150 and the paraffin stream 250 are similar in composition such that processes, and economic advantages, may be analyzed to showcase the enhancement of the technology. In one example, the embodiment of FIG. 2, provides a reduction of hydrogen gas used to provide ethane and propane through the24CHEM0013 - WO-ORD11 hydrocracking unit 206 compared to the process of FIG. 1. Thus, the operational expenditures to operate the process of FIG. 2 may decrease as the consumption of hydrogen gas, the necessary amount of catalyst within the hydrocracking unit 206, and the design size of the reaction vessel within the hydrocracking unit 206 are reduced. Capital expenditures will be present in the implementation of the embodiment of FIG. 2, however the operational expenditures will overcome the capital expenditures in operation. For example, at the time of the application and using the embodiment of FIG. 1 as a baseline cost, the capital expenditures to implement the embodiment of FIG. 2 would increase by about 9 million US dollars (MMUSD) to implement the C4 separation unit 210 but would decrease the capital expenditures of the hydrocracking unit 206 by 4.1 MMUSD. Similarly, at the time of the application and using the embodiment of FIG. 1 as a baseline cost, the operational expenditures to implement the embodiment of FIG. 2 would increase by about 3.05 million US dollars (MMUSD) to implement the C4 separation unit 210 but would decrease the operational expenditures of the hydrocracking unit 206 by 11.04 MMUSD. Thus, providing an economical advantage as capital expenditures would increase by 4.9 MMUSD and operational expenditures would decrease by 7.6 MMUSD. The analysis reveals a net 4.7 MMUSD first year cost decrease and a 8.0 MMUSD operational expenditure reduction in cost every year thereforth. Therefore, the embodiment of FIG. 2 is advantageously more resource-efficient than the embodiment of FIG. 1.

[0036] Similarly, the configuration of FIG. 1 and FIG. 2 are compared in Table 2. The table below illustrates the yields at 85% conversion that correlate to the system 100 and the system 200 as discussed above. Various values and calculations may be obtained and / or performed from the combination of information presented in the table below.Table 224CHEM0013 - WO-ORD12

[0037] Table 2 above compares two operational conditions which may be used to compare the system 100 and the system 200 each using a 30:70 molar percent ratio of 2-methylpropane to n- butane, as discussed above at a lower steam cracker conversion rate of 85 percent. For example, Table 2 illustrates a total olefin increased conversion of at least 2.2 percent of system 200 of FIG. 2 over the conventional system 100 of FIG. 1. Similar economic advantages apply to the operational conditions of Table 2 as presented above in Table 1 discussion.

[0038] As briefly mentioned above, in one example, the paraffin stream 250 includes about 50:50 molar percent ratio of 2-methylpropane to n-butane. Disclosed herein are the additional operating parameters in the implementation of the paraffin stream 250 including about 50:50 molar percent ratio of 2-methylpropane to n-butane. In that example, the reboiler of the C4 separation unit 210 uses 21.45 MMkcal / hr. Furthermore, the flowrate of the 2-methylpropane-rich stream 258 may be about 34.56 TPH. In some examples, the hydrogen supply unit 202 provides about 0.66 TPH flowrate of hydrogen gas through the hydrogen -rich stream 252 to the 2-methylpropane-rich stream 258. The combined flowrate of the hydrogen-rich stream 252 and the 2-methylpropane-rich stream 258 may be about 35.22 TPH to be fed to the heating unit 204. In some examples, the heating unit 204 may provide a duty of about 1.33 MMKcal / hr to heat the hydrogen-rich stream 252 and the 2-methylpropane-rich stream 258. In some examples, the reaction vessel within the hydrocracking unit 206 may be approximately about 1.86 m by about 8.84 m. In some examples, the reaction vessel may use the catalyst at a rate of 38 tons per 3 reaction cycles.

[0039] The embodiments and the illustrative values provided in the above description for the 50:50 molar percent ratio of 2-methylpropane to n-butane may be further used to compare the process described in FIG. 1 to analyze, at least, economic advantages. In one example, the operational expenditures to operate the process of FIG. 2 (50:50 molar percent ratio) may be less costly as the consumption of hydrogen gas, the necessary amount of catalyst within the hydrocracking unit 206, and the design size of the reaction vessel within the hydrocracking unit 206 are reduced. Capital expenditures will be present in the implementation of the embodiment of FIG. 2, however the operational expenditures will overcome the capital expenditures in operation. For example, at the time of the application and using the embodiment of FIG. 1 as a baseline cost,24CHEM0013 - WO-ORD13 the capital expenditures to implement the embodiment of FIG. 2 (50:50 molar percent ratio) would increase by about 7 million US dollars (MMUSD) to implement the C4 separation unit 210 but would decrease the capital expenditures of the hydrocracking unit 206 by 2.7 MMUSD. Similarly, at the time of the application and using the embodiment of FIG. 1 as a baseline cost, the operational expenditures to implement the embodiment of FIG. 2 (50:50 molar percent ratio) would increase by about 3.36 million US dollars (MMUSD) to implement the C4 separation unit 210 but would decrease the operational expenditures of the hydrocracking unit 206 by 7.6 MMUSD. Thus, providing an economical advantage as capital expenditures would increase by 4.3 MMUSD and operational expenditures would decrease by 4.2 MMUSD. The analysis reveals a net first year increase by 0.1 MMUSD and a 4.2 MMUSD operational expenditures reduction in cost every year thereforth. Therefore, the embodiment of FIG. 2 (50:50 molar percent ratio) is advantageously less costly than the embodiment of FIG. 1 while producing an increase in olefin product and reducing produced methane.

[0040] FIG. 3 is a schematic representation of an enhanced olefin production system 300 using a C4 separation unit 310 to supply 2-m ethylpropane to a hydrocracking unit 306 and a C3 separation unit 312 to produce a portion of the feed to the C4 separation unit 310, according to an example. The olefin production system 300 includes various units, such as a C4 separation unit 310, a hydrogen supply unit 302, a heating unit 304, a hydrocracking unit 306, and a steam cracker unit 308. The olefin production system 300 includes various streams such as streams 350, 352, 354, 356, 358, 360 and optional streams 370, 372, and / or 374. The embodiment of FIG. 3 further includes the C3 separation unit 312 and streams 362, 364, and 366.

[0041] The C3 separation unit 312 is configured to receive a C2-C4 feed stream 362 and to produce a butane-rich stream 364 and a C2-C3-rich stream 366. In some examples, the C2-C4 feed stream 362 may be supplied from a crude distillation unit, a hydrotreater unit, and / or a hydrocracker unit (each not shown). In some examples the C2-C4 feed stream 362 may be a collection of alkanes from the aforementioned units within a saturated gas condensate unit (not shown). In that example, the C2-C4 feed stream 362 is an output from the saturated gas condensate unit that is supplied to the C3 separation unit 312. The butane-rich stream 364 may be supplied to the C4 separation unit 310. The C3 separation unit 312 may be fluidly connected to the C424CHEM0013 - WO-ORD14 separation unit 310 and the steam cracker unit 208. The C2-C3-rich stream 366 may be supplied to the steam cracker unit 308.

[0042] FIG. 4 is an illustration of a method in which C3 and C4 streams are separated to feed the stream cracker unit, according to an example. The method 400 includes steps 402, 404, 406, 408, 410, 412, 414, 416, 418, and 420. The following method 400 discussion will reference FIG. 3 numerals for ease of explanation. However, the method 400 is not limited to the embodiment of FIG. 3.

[0043] Step 402 includes sourcing a paraffin feed stream 350 from a total hydrogenation unit (not shown in FIG. 3). As discussed above, the paraffin stream 250 can contain substantially mixed butanes, such as 2-methylpropane and n-butane.

[0044] The method 400 includes step 404 of separating the paraffin feed stream 350 containing substantially 2-methylpropane and n-butane to produce a 2-methylpropane-rich stream 358 and a n-butane-rich stream 360 within the C4 separation unit 310. In some examples, a distillation column within the C4 separation unit 310 may be used to separate 2-methylpropane and n-butane based on boiling point and / or density.

[0045] The method 400 includes step 406 of separating a C2-C4 feed stream to produce the butane-rich stream 364 and a C2-C3-rich stream 366. The butane-rich stream 364 may be mixed with the paraffin feed stream 350 resulting in at least a portion of the paraffin feed stream 350 including the butane-rich stream 364.

[0046] The method 400 includes step 408 of heating the 2-methylpropane-rich stream by at least by about 5 to about 50 degrees Celsius. The heating unit 304 may provide the thermal energy to raise the 2-methylpropane-rich stream 358. In some examples, the method 400 may further include mixing the 2-methylpropane-rich stream 358 with the hydrogen-rich stream 352.

[0047] The method 400 includes step 410 of hydrocracking the 2-methylpropane-rich stream 358 in a presence of hydrogen to produce a hydrocracked product stream 356 containing substantially ethane and propane.

[0048] The method 400 includes step 412 of mixing the C2-C3-rich stream 366 and the n-butane- rich stream 360 to produce a feed to the steam cracker unit 308. As briefly discussed above, the C2-C3-rich stream 366 contains ethane and propane that are desired feeds to the steam cracker unit 308. Furthermore, the n-butane-rich stream 360 has empirically shown to also be a desirable feed24CHEM0013 - WO-ORD15 to the steam cracker unit 308. Therefore, mixing the C2-C3-rich stream 366 and the n-butane-rich stream 360 may reduce cost compared to routing them independently to the steam cracker unit 308.

[0049] The method 400 includes step 414 of mixing the n-butane-rich stream 360, the C2-C3- rich stream 366, and the hydrocracked product stream 356. In some examples, as discussed above, the n-butane-rich stream 360 may contain at least a portion of the C2-C3-rich stream 366. In that example, the hydrocracked product stream 356 and the mixed C2-C3-rich stream 366 and the n- butane-rich stream 360 may be further mixed to provide a desirable feed to the steam cracker unit 308.

[0050] The method 400 includes step 416 of separating methane from the hydrocracked product stream 356. As discussed in FIG. 2, in some examples the methane gas may be separated downstream from the hydrocracking unit 206 and / or from the hydrocracked stream 256. As discussed above, the methane gas may also be separated within the hydrocracking unit 206. FIG. 4 illustrates an optional pathway (A) that separates methane from the hydrocracked product before step 414. Alternatively, the hydrocracked product stream 356 may be supplied to step 414 as shown by optional pathway (B).

[0051] The method 400 includes step 418 of supplying the n-butane-rich stream 460, the C2-C3- rich stream 366, and the hydrocracked product stream 356 to a steam cracker unit 308 to produce ethene and propene. As discussed above, the n-butane-rich stream 460, the C2-C3-rich stream 366, and the hydrocracked product stream 356 may be individually supplied to the steam cracker unit 308 in some examples. The method 400 further includes step 420 of separating methane from an olefin steam produced by the steam cracker containing ethene and propene. As illustrated by optional stream 274, any produced methane may be separated from the product of the steam cracker unit 308 to be used as, for example, a fuel gas to power other units.EXPERIMENTS AND EXAMPLES

[0052] The below examples are presented to provide experimental data for various examples of operations discussed above.

[0053] Example 1: As discussed above, the paraffin stream 150 contains at least mixed butanes including 2-methylpropane and n-butane. The conversion rates of various feeds to the steam24CHEM0013 - WO-ORD cracker unit 108 were analyzed to determine enhancement conditions suitable for implementation to the system 100 of FIG 1. The analysis involved the conversion rates of each: ethane, propane, 2-methylpropane, n-butane, a 70:30 mol% (n-butane:2-methylpropane), the BUTEP process of FIG. 1, and the BUTEP process of FIG. 2, feeds to the steam cracker. The results are shown in the below Table 3. Various values and calculations may be obtained and / or performed from the combination of information presented in the table below.Table 3: Yield Analysis Results of Steam Cracker Feeds.

[0054] Table 3 above illustrates the steam cracker olefin conversion rates of each feed used in the determination of enhancement disclosed above. Table 3 illustrates an ethane feed to the stream cracker within the steam cracker unit 108 produces 79 percent ethene and 2 percent propene, to yield a total 81 percent olefins. Furthermore, the quality of olefin produced may be a factor in enhancement strategy as propene may be more valuable than ethene. Therefore, Table 3 also illustrates the propene to ethene ratio. Similarly, the propane, 2-methylpropane, n-butane, and the 70:30 Mix feed to the steam cracker may be evaluated. The enhancement of the BUTEP technology of this application may be illustrated in the comparison between the mixed butane BUTEP (FIG. 1) and the 2-methylpropane BUTEP (FIG. 2). The total percentage of olefin produced between the mixed butane feed of system 100 and the 2-methylpropane feed of system 200 is surprising and unexpected as they are similar in that both are within at least 0.7 total percent. The similar total percents indicate the n-butane may be removed from the conventional mixed butane feed, as illustrated in FIG. 2, to reduce cost and gain additional product yield, as discussed above.

[0055] Example 2: As discussed above, the BUTEP process of FIG. 2 is configured to process the 2-methylpropane-rich stream 258, which is about a third of the flow originally fed to the24CHEM0013 - WO-ORD17BUTEP process of FIG. 1. The below Table 4 illustrates a three run experiment wherein the 2- methylpropane-rich stream produces propane and ethane. Various values and calculations may be obtained and / or performed from the combination of information presented in the table below.Table 4: Yield Analysis Results of 2-Methylpropane in BUTEP.

[0056] A product analysis of each run of the 2-methylpropane-rich stream 258 are shown within Table 4. The results show that 2-methylpropane is effectively converted above 82 percent while producing at least 75 wt. % of ethane and propane, a desired steam cracker feed. Thus, the experimental analysis of the 2-methylpropane rich feed stream processed by the BUTEP process presented in Table 4, empirically yields a desirable conversion to ethane and propane from the separated 2-methylpropane rich feed stream via the process discussed above.

[0057] Therefore, the n-butane-rich stream and the hydrocracked stream, produced from the BUTEP process of the 2-methylpropane rich feed stream, together yield an increased olefin production process while reducing cost and reducing produced methane.

[0047] 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 the24CHEM0013 - WO-ORD18 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 features from any of the other examples. In further examples, additional features may be added to the specific examples described herein.

Claims

24CHEM0013 - WO-ORD19CLAIMSWhat is claimed is:

1. A method of producing olefins, the method comprising: separating a paraffin feed stream containing substantially 2-methylpropane and n-butane to produce a 2-methylpropane-rich stream and a n-butane-rich stream; hydrocracking the 2-methylpropane-rich stream in a presence of hydrogen to produce a hydrocracked product stream containing substantially ethane and propane; and supplying the n-butane-rich stream and the hydrocracked product stream to a steam cracker, thereby to produce ethene and propene.

2. The method of claim 1, further comprising: sourcing the paraffin feed stream from a total hydrogenation unit, a crude distillation unit, or a hydrocracker unit before separating the paraffin feed stream.

3. The method of claim 1, further comprising: heating the 2-methylpropane-rich stream to about 375 degrees Celsius to about 425 degrees Celsius prior to hydrocracking the 2-methylpropane-rich stream.

4. The method of claim 1, further comprising: separating a C2-C4 feed stream to produce at least a portion of the paraffin feed stream containing substantially 2-methylpropane and n-butane and a C2-C3-rich stream.

5. The method of claim 4, further comprising: mixing the C2-C3-rich stream and the n-butane-rich stream prior to supplying them to the steam cracker.

6. The method of claim 1, further comprising: separating methane from the hydrocracked product stream prior to supplying the hydrocracked product stream to the steam cracker or separating methane from an olefin steam produced by the steam cracker containing ethene and propene.24CHEM0013 - WO-ORD207. The method of claim 1, wherein separating the paraffin feed stream is performed by using a distillation column using a heat pump compressor to heat the paraffin feed stream.

8. The method of claim 1, further comprising: mixing the n-butane-rich stream and the hydrocracked product stream prior to supplying them to the steam cracker.

9. A system comprising: a C4 separation unit configured to receive a paraffin feed stream containing substantially 2- methylpropane and n-butane and to produce a 2-methylpropane-rich stream and a n- butane-rich stream; a hydrocracking unit in fluid communication with the C4 separation unit and configured to receive and crack the 2-methylpropane-rich stream in a presence of hydrogen to produce a hydrocracked product stream containing substantially ethane and propane; and a steam cracker unit in fluid communication with the C4 separation unit and the hydrocracking unit and configured to receive the n-butane-rich stream and the hydrocracked product stream and to produce ethene and propene.

10. The system of claim 9, wherein the hydrocracking unit contains a hydrocracking catalyst containing a metal on a support, the metal being palladium, platinum, nickel, cobalt, manganese, iron, rhodium, iridium, ruthenium, tungsten, zirconium, or combinations thereof.

11. The system of claim 9, wherein the C4 separation unit contains a distillation column connected to a reboiler energized by steam or a heat pump compressor.

12. The system of claim 9, wherein the 2-methylpropane-rich stream contains at least about 90 wt. % of 2-methylpropane.4CHEM0013 - WO-ORD2113. The system of claim 9, wherein the n-butane-rich stream contains about 98 mol % of n- butane.

14. The system of claim 9, further comprising: a C3 separation unit in fluid communication with the C4 separation unit and operable to receive a C2-C4 feed stream and produce C2-C3-rich stream containing substantially ethane and propane and at least a portion of the paraffin feed stream.

15. The system of claim 14, wherein the C2-C3-rich stream containing substantially ethane and propane is supplied to the steam cracker unit.

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