Method for converting petroleum into light olefins by utilizing pretreatment composite device and steam enhanced catalytic cracking device

Abstract

A process for converting a petroleum feed to light olefins can include pre-treating the petroleum feed to form one or more pre-treated petroleum feeds, and fractionating the one or more pre-treated petroleum feeds to form a methane stream, an ethane stream, a C3-C4 stream, a light liquid fraction, and a heavy liquid fraction. The process may also include methane cracking the methane stream to form hydrogen, steam cracking the ethane stream to form a steam cracked product; dehydrogenating the C3-C4 stream to form a dehydrogenated stream; and subjecting the light liquid fraction and the heavy liquid fraction to steam enhanced catalytic cracking (SECC) to form an SECC product.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Non-Provisional Application No. 17 / 865,823, filed on July 15, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments of the present disclosure relate generally to the conversion of petroleum into basic intermediates, and more particularly to the conversion of crude oil into light olefins. Background Art

[0004] Light olefins (such as ethylene, propylene and butenes) and aromatics (such as benzene, toluene and xylenes) are basic chemical intermediates widely used in the petrochemical and chemical industries. Thermal cracking and steam pyrolysis are the main types of processes for the formation of these materials. Typical feedstocks for steam pyrolysis include petroleum gases (such as ethane) and distillate oils (such as naphtha, kerosene and gas oil). These feedstocks have limited availability and require expensive and energy-intensive process steps before they are converted into basic intermediates.

[0005] Many chemical producers are further constrained by the availability and quality of feedstock from nearby refineries due to their reliance on refinery byproducts as feedstock. Chemical producers are also constrained by the high costs of refining and its associated fuel markets. These can negatively impact the economic value of refinery-sourced feedstock. Higher global vehicle dye efficiency standards will further reduce fuel demand and reduce refinery profits. This could complicate the economics of the chemical supply market.

[0006] Therefore, there remains a need for improved methods and systems for converting crude oil directly into basic chemical intermediates, such as lower olefins and aromatics. Summary of the invention

[0007] Embodiments of the present disclosure meet this need for increasing the production of light olefins from crude oil by providing methods and systems specifically for converting a substantial portion of the crude oil to light olefins and recycling or upgrading the remainder, thereby maximizing the financial value of the crude oil.

[0008] According to one embodiment of the present disclosure, a method for converting a petroleum feedstock into light olefins may include pretreating the petroleum feedstock to form one or more pretreated petroleum feedstocks, and fractionating the one or more pretreated petroleum feedstocks to form a methane stream, an ethane stream, a C 3 -C 4 The method may also include methane cracking the methane stream to form hydrogen, steam cracking the ethane stream to form steam cracking products; 3 -C 4dehydrogenating the stream to form a dehydrogenated stream; and performing steam enhanced catalytic cracking (SECC) on the light liquid fraction and the heavy liquid fraction to form a SECC product.

[0009] According to another embodiment of the present disclosure, a system for converting a petroleum feedstock into light olefins may include a pretreatment complex, which is configured to pretreat the petroleum feedstock to form one or more pretreated petroleum feedstocks; a separator 160, which is fluidly connected to the pretreatment complex and configured to fractionate the one or more pretreated petroleum feedstocks to form a methane stream, an ethane stream, a C 3 -C 4 a methane cracker fluidly connected to the separator and configured to methane crack the methane stream to form hydrogen; a steam cracker fluidly connected to the separator and configured to steam crack the ethane stream to form a steam cracked product; a dehydrogenation unit fluidly connected to the separator and configured to make C 3 -C 4 The stream is dehydrogenated to form a dehydrogenated stream; and one or more steam enhanced catalytic crackers fluidly connected to the separator and configured to steam enhanced catalytic crack the light liquid fraction and the heavy liquid fraction to form steam enhanced catalytic cracking products.

[0010] Although the concepts of the present disclosure are described herein primarily with reference to crude oil and light olefins, it is contemplated that these concepts will be applicable to any petrochemical feedstock and any basic chemical intermediate.

[0011] BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The following detailed description of specific embodiments of the present disclosure may be best understood when read in conjunction with the following drawings, in which like structures are represented by like reference numerals and in which:

[0013] Figure 1 is a schematic diagram of an embodiment of the present disclosure.

[0014] Figure 2 is a schematic diagram of an embodiment of the present disclosure. DETAILED DESCRIPTION

[0015] "API" means the American Petroleum Institute.

[0016] “C x ” refers to a molecule with x carbons.

[0017] "°C" means degrees Celsius.

[0018] "Mol. %" means molar percentage.

[0019] "MPa" means megapascal.

[0020] "SECC" means steam enhanced catalytic cracking.

[0021] "wt." means weight.

[0022] "wt. %" or "weight %" means percent by weight.

[0023] like Figure 1 As shown and discussed in more detail herein, a system 100 for converting a petroleum feed 105 into light olefins may include a pretreatment complex 106 configured to pretreat the petroleum feed 105 to form one or more pretreated petroleum feeds 110; a separator 160 fluidly connected to the pretreatment complex 106 and configured to fractionate the one or more pretreated petroleum feeds 110 to form a methane stream 115, an ethane stream 120, a C 3 -C 4 125, a light liquid fraction 130, and a heavy liquid fraction 135; a methane cracker 116, which is fluidly connected to the separator 110 and is configured to methane crack the methane stream 115 to form hydrogen 118; a steam cracker 123, which is fluidly connected to the separator 110 and is configured to steam crack the ethane stream 120 to form a steam cracked product 121; a dehydrogenation unit 127, which is fluidly connected to the separator 110 and is configured to make C 3 -C 4 stream 125 is dehydrogenated to form a dehydrogenated stream 126 ; and one or more steam enhanced catalytic crackers 131 fluidly connected to the separator 110 and configured to steam enhanced catalytic crack the light liquid fraction 130 and the heavy liquid fraction 135 to form steam enhanced catalytic cracking products 140 .

[0024] Although Figure 1 It seems that only one steam enhanced catalytic cracker 131 is shown, but it should be understood that 131 may show one or more (i.e., many) steam enhanced catalytic crackers, in particular, a first steam enhanced catalytic cracker and a second steam enhanced catalytic cracker, which together comprise the steam enhanced catalytic cracker 131. Showing one steam enhanced catalytic cracker 131 is intended to simplify Figure 1 Flow chart of .

[0025] Furthermore, it should be understood that the use of "light" and "heavy" as identifiers for one or more steam enhanced catalytic crackers 131 is only for the purpose of referencing the feed streams that may enter one or more steam enhanced catalytic crackers 131. For example, a light (also referred to herein as a "first") steam enhanced catalytic cracker may be understood to have a lighter hydrocarbon feed having a lower boiling point than the feed for a heavy steam enhanced catalytic cracker. Similarly, a heavy (also referred to herein as a "second") steam enhanced catalytic cracker may be understood to have a heavier hydrocarbon feed having a higher boiling point than the feed for the light steam enhanced catalytic cracker.

[0026] The system 100 may also include a product separator 165, which is fluidly connected to a methane cracker, a steam cracker, a dehydrogenation unit, one or more steam enhanced catalytic crackers, and a pretreatment complex. The pretreatment complex 106 may also include a solvent deasphalting unit 107, a gasification unit 108, and a hydroprocessing unit 109. The hydroprocessing unit 109 may include a hydrocracker, a hydroprocessing unit, or both. The pretreatment complex may be fluidly connected to the gasification unit 108 and the hydroprocessing unit 109, and may produce a deasphalted oil stream 150 and an asphaltene stream 145 with the petroleum feed 105. The gasification unit may be fluidly connected to the hydroprocessing unit 109, and may produce a hydrogen-rich stream 155 and a carbon-rich stream 156 with the asphaltene stream 145. The hydroprocessing unit may be fluidly connected to the separator 160, and may be configured to produce one or more pretreated petroleum feeds 110 with the deasphalted oil stream 150. The hydroprocessing unit may be additionally configured to produce one or more pretreated petroleum feeds 110 using at least one of the hydrogen-rich stream 155 and the hydrogen 118 .

[0027] like Figure 2 As shown and discussed in more detail herein, the system 200 for converting petroleum feedstock into light olefins may include any components of system 100. System 200 may further include a flash tank 203. The flash tank may be fluidically connected to the pre-treatment complex and one or more steam enhanced catalytic crackers. The flash tank 203 may be configured to fractionate the whole crude oil 201 into a light crude fraction and a petroleum feed. The flash tank may send the light crude fraction to one or more steam enhanced catalytic crackers.

[0028] Also like Figure 1 As shown, the method for converting a petroleum feed 105 into light olefins can utilize any of the aforementioned systems and can also include pre-treating the petroleum feed 105 to form one or more pre-treated petroleum feeds 110. The method can then include fractionating the one or more pre-treated petroleum feeds 110 to form a methane stream 115, an ethane stream 120, a C 3 -C 4Stream 125, light liquid fraction 130 and heavy liquid fraction 135. The method may also include methane cracking methane stream 115 to form hydrogen, steam cracking ethane stream 120 to form steam cracked products 126, and C 3 -C 4 Stream 125 is dehydrogenated to form dehydrogenated stream 126 , and light liquid fraction 130 and heavy liquid fraction 135 are subjected to steam enhanced catalytic cracking (SECC) to form SECC product 140 .

[0029] like Figure 1 As shown, the petroleum feed 105 may be whole crude oil. Figure 2 As shown, petroleum feed 205 can be a part of whole crude oil. Whole crude oil 201 can be fractionated into light crude fraction 202 and petroleum feed 205. Whole crude oil 201 can be fractionated into light crude fraction 202 and petroleum feed 205 in flash tank 203. Light crude fraction 202 can be subjected to steam enhanced catalytic cracking (SECC). Light crude fraction 202 can be subjected to SECC alone. Alternatively, light crude fraction 202 can be combined with one or both of light liquid fraction 230 and heavy liquid fraction 240, and combined stream can be subjected to SECC. In some embodiments, light crude fraction 202 can be subjected to no further treatment before SECC, except that light crude fraction 202 is optionally combined with other streams before SECC is carried out to combined stream. Light crude fraction 202 can comprise hydrocarbons with boiling point lower than 300°C. For example, at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.% of the light crude fraction may have a boiling point below 300°C.

[0030] Whole crude oil 105, 201 may have an API gravity of 10° to 40° and a sulfur content of 0.05wt.% to 5.00wt.% sulfur. Whole crude oil may be Arabian extra light oil, Arabian light oil or Arabian heavy oil. Arabian extra light crude oil may be a crude oil derived from Saudi Arabia. Arabian extra light crude oil may have an API gravity of 33° to 40° and a sulfur content of 0.05wt.% to 1.5wt.%. For example, Arabian extra light crude oil may have an API gravity of about 40.0° and a sulfur content of about 1.09wt.%. Arabian light crude oil may be a crude oil derived from Saudi Arabia. Arabian light crude oil may have an API gravity of 30° to 33° and a sulfur content of 1.2wt.% to 2.0wt.%. For example, Arabian extra light crude oil may have an API gravity of about 32.8° and a sulfur content of about 1.97wt.%. Arabian heavy crude oil may be a crude oil derived from Saudi Arabia. Arabian heavy crude oil may have an API gravity of 10° to 30° and a sulfur content of 2.0 wt.% to 5.0 wt.%. For example, Arabian light crude oil may have an API gravity of approximately 27.7° and a sulfur content of approximately 2.87 wt.%.

[0031] Reference again Figure 1 , the petroleum feed 105 may be pretreated in a pretreatment complex 106. The pretreatment complex 106 may include a solvent deasphalting unit 107, a gasifier 108, and a hydroprocessing unit 109, such as a hydrotreater or a hydrocracker. Pretreating the petroleum feed 105 may include solvent deasphalting the petroleum feed 105. Solvent deasphalting the petroleum feed 105 may produce one or both of an asphaltene stream 145 and a deasphalted oil stream 150. Solvent deasphalting the petroleum feed 105 may include contacting the petroleum feed 105 with a solvent at a deasphalting temperature, a deasphalting pressure, and a deasphalting solvent / feed ratio. The solvent may include a light paraffinic solvent, such as propane, etc. 3 To C 7 The solvent may also be a light paraffinic hydrocarbon, such as, but not limited to, n-propane, n-butane, n-pentane, n-hexane, n-heptane, or a combination thereof. The deasphalting temperature may be in the range of 120°C to 160°C. The deasphalting pressure may be in the range of 2 to 6 MPa, 3 MPa to 5 MPa, or 3.5 MPa to 4.5 MPa. The solvent / feed ratio may be in the range of 3 to 6, 4 to 5, or 4.25 to 4.76.

[0032] The deasphalted oil stream 150 may contain less than 10.0 wt.% asphaltenes. The deasphalted oil stream 150 may contain 15 wt.% to 60 wt.% aromatics, 30 wt.% to 80 wt.% saturated hydrocarbons, and 0.2 wt.% to 4.5 wt.% sulfur. ... -1 Up to 10s -1The asphaltene stream 145 may have a viscosity of 5 to 60 centipoise at a shear rate of 1000 s and a temperature of 25° C. The asphaltene stream 145 may contain 25 wt.% to 100 wt.% asphaltene. -1 Up to 10s -1 The asphaltene stream 145 may have a viscosity of 20 to 480 centipoise at a shear rate of 100 and a temperature of 60°C. In an embodiment, the asphaltene stream 145 may also include non-hydrocarbon components and impurities. In this way, the solvent deasphalting unit 107 can remove asphaltenes, non-hydrocarbon components, impurities, or a combination thereof from the petroleum feed 105 to form a deasphalted oil stream 150. For example, the solvent deasphalting unit 107 can remove nitrogen-containing compounds, sulfur-containing compounds, Conradson carbon residue (CCR), and metal compounds such as nickel and vanadium. In an embodiment, removing non-hydrocarbon components and impurities like the previous one can improve the efficiency of downstream processing units by reducing the coking deactivation rate of various catalysts used therein.

[0033] Pretreating the petroleum feed 105 may include gasifying the asphaltene stream 145. Gasifying the asphaltene stream 145 may include exposing the asphaltene stream 145 to a low oxygen environment, such as less than 10 mol.%, less than 5 mol.%, less than 2.5 mol.%, less than 1 mol.%, less than 0.5 mol.%, or even less than 0.1 mol.% O 2 . Gasification may include exposing the asphaltene stream 145 to a temperature of 700° C. to 1200° C. and a pressure of 1 bar to 29 bar while being exposed to a low oxygen environment. Gasifying the asphaltene stream 145 may produce hydrogen, carbon monoxide, or both. Hydrogen may also be contained in the hydrogen-rich stream 155. The hydrogen-rich stream 155 may be at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.%, at least 99 wt.%, or at least 99.9 wt.% of hydrogen. Carbon monoxide may be combined with the hydrogen-rich stream 155, or may be separated and removed from the carbon-rich stream 156. The carbon-rich stream 156 may be at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.%, at least 99 wt.%, or at least 99.9 wt.% of carbon monoxide. In an embodiment, the gasified asphaltene stream 145 may produce hydrogen and carbon monoxide in a weight percentage of 1:5 to 1:2. This may also include any weight percentage between 1:5 and 1:2, such as 1:4, 1:3, 1:4.5, 1:3.5, or 1:2.5, and any combination of ratios therein.

[0034] The pretreated petroleum feed 105 may include a hydrotreated deasphalted oil stream 150. The hydrotreated deasphalted oil stream 150 may include a hydrocracked or hydrofinished deasphalted oil stream 150. The hydrotreated deasphalted oil stream 150 may include contacting the deasphalted oil stream 150 with hydrogen at a temperature of 280° C. to 450° C. and a pressure of 5 bar to 160 bar. The hydrogen may be derived from a hydrogen-rich stream 155 produced by a gasification process. In some embodiments, at least some of the hydrogen may be produced by other means, such as electrochemically, by a water-gas shift reaction, or by a methane cracker.

[0035] As previously mentioned, hydrotreating a deasphalted oil stream can be classified as hydrocracking. Hydrocracking a deasphalted oil stream can include contacting the deasphalted oil stream with hydrogen in the presence of a catalyst. The catalyst can be a bifunctional catalyst having an acid function and a hydrogenation function. The catalyst can include halogenated alumina, zeolite, amorphous silica-alumina or clay. As previously mentioned, hydrotreating a deasphalted oil stream can also be classified as hydrofining. Hydrofining a deasphalted oil stream can include contacting the deasphalted oil stream with a desulfurization catalyst and a denitrification catalyst in the presence of hydrogen. These catalysts can be located in a continuous bed or can be combined in a single bed. The desulfurization catalyst can include cobalt and molybdenum. The denitrification catalyst can include alumina, nickel-molybdenum or both.

[0036] Reference again Figure 1 The pretreated petroleum feed 110 can be fractionated in a separator 160 to form a methane stream 115, an ethane stream 120, and a C 3 -C 4 Stream 125, a light liquid fraction 130, and a heavy liquid fraction 135. Fractionation of the petroleum feed may be performed in a single separator 160 (as shown), such as a distillation column, or in several separators operated in series.

[0037] The methane stream 115 may be at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.%, at least 99 wt.%, or even at least 99.9 wt.% methane gas. The methane stream 115 may be substantially free of impurities such as sulfur. The methane stream 115 may be subjected to methane cracking. Methane cracking may include exposing the methane stream 115 to a methane cracking catalyst in a methane cracker 116. The methane cracking catalyst may comprise Ni / CeO 2 、NiLa 2 O 3 、Ni / SiO 2 、Ni / Mg-O-Al、Fe / CeO 2 、Fe / La 2 O 3 、Fe / SiO 2 、Ni / SiO2 、Fe / SiO 2 、Co / SiO 2 、Rh / Al 2 O 3 、Rh / Al 2 O 3 or Nd 2 O 3 The methane stream 115 may be exposed to the methane cracking catalyst at a temperature of at least 500°C, at least 600°C, at least 650°C, at least 700°C, at least 750°C, 500°C to 1000°C, 600°C to 1000°C, 700°C to 1000°C, 600°C to 900°C, 650°C to 850°C, or any subset thereof.

[0038] Methane cracking The methane stream 115 can produce hydrogen. Hydrogen can be contained in the hydrogen stream 118 of methane cracking. The hydrogen stream 118 of methane cracking can be at least 50wt.%, at least 60wt.%, at least 70wt.%, at least 80wt.%, at least 90wt.%, at least 95wt.%, at least 99wt.% or even at least 99.9wt.% hydrogen. The hydrogen can be sent to a hydroprocessing unit or can be used for an external process. The methane cracker 116 can also produce solid carbon materials. The method can also include methane cracking of the methane recycle stream 117. For example, the methane recycle stream 117 can contain at least 50wt.%, at least 60wt.%, at least 70wt.%, at least 80wt.%, at least 90wt.% or at least 95wt.% of methane. The methane recycle stream 117 can be separated from other components in the product separator 165.

[0039] The ethane stream 120 may contain at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.%, at least 99 wt.%, or even at least 99.9 wt.% of ethane gas. The ethane stream 120 may be steam cracked in a steam cracker 123 to form a steam cracked product 121. Steam cracking the ethane stream 120 may include contacting the ethane stream 120 with steam at a steam cracking temperature, a steam cracking pressure, and a steam-feed ratio. The steam cracking temperature may be 800° C. to 950° C., 800° C. to 900° C., 825° C. to 875° C., or any subset thereof. The steam cracking pressure may be 0.8 bar to 5 bar, 0.8 bar to 3 bar, 0.8 bar to 1.5 bar, 0.8 bar to 1.2 bar, or any subset thereof. The steam-feed ratio may be 0.3 to 0.8. The ethane stream 120 may contact the steam in the absence of a catalyst.

[0040] The method may also include steam cracking a steam cracking recycle stream 122 in a steam cracker 123. The steam cracking recycle stream 122 may contain ethane gas. For example, the steam cracking recycle stream may contain at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, or at least 95 wt.% of ethane. The ethane gas may be separated from other components in a product separator 165. The steam cracking product 121 may contain olefins, such as ethylene and propylene. For example, the steam cracking product may contain at least 40 wt.%, at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, or at least 95 wt.% of olefins.

[0041] C 3 -C 4 Stream 125 may comprise at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.%, at least 99 wt.%, or even at least 99.9 wt.% of the combined weight of C 3 and C 4 Gas. C 3 -C 4 The gas may be an alkane such as propane and butane. 3 -C 4 Stream 125 may be dehydrogenated in dehydrogenator 127 to form dehydrogenated stream 126. 3 -C 4 Dehydrogenation of stream 125 may include dehydrogenating C 3 -C 4 Stream 125 is contacted with a dehydrogenation catalyst at a temperature of 575°C to 620°C and a pressure of 1 bar to 5 bar or 2 bar to 5 bar. The dehydrogenation catalyst may comprise CrO 3 / Al 2 O 3 、Pt-Sn / Al 2 O 3 Or both. The dehydrogenation catalyst may also include a zinc silicate support material, one or more alkali metals or alkaline earth metals and one or more platinum group metals. The zinc silicate support material may also include an MFI framework-type structure comprising at least silicon and zinc. As used herein, an "MFI framework-type structure" may sometimes be referred to as a ZSM-5 framework-type structure. Zeolite framework types, such as MFI framework types, are disclosed in "Zeolite Framework Type Atlas, Fifth Edition" by Baerlcher, Meier and Olson, the entire contents of which are incorporated herein by reference.

[0042] The method may include dehydrogenating the dehydrogenation recycle stream 128. The dehydrogenation recycle stream may include C 3 -C 4For example, the dehydrogenation recycle stream may contain at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, or at least 95 wt.% of C 3 -C 4 Alkanes. The dehydrogenated stream 126 may include alkanes such as propane and butane. For example, the dehydrogenated stream 126 may include at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, or at least 95 wt.% of alkanes such as propane and butane.

[0043] The light liquid fraction 130 may include C 5 Hydrocarbons to hydrocarbons having a boiling point of 300°C at 1 atmosphere (atm). The heavy liquid fraction 135 may include hydrocarbons having a boiling point of at least 300°C at 1 atm. The light liquid fraction 130 and the heavy liquid fraction 135 may be subjected to SECC in a steam enhanced catalytic cracker 131. The SECC of the two fractions may occur in a separate reactor or in the same reactor. The SECC of the two fractions may form a SECC product 140. SECC may also include exposing the light liquid fraction 130 or the heavy liquid fraction 135 or both to a SECC catalyst at a SECC temperature and a SECC steam / feed weight ratio. The SECC catalyst may include ZSM-5. For example, the SECC catalyst may include a metal supported on ZSM-5. The metal supported on ZSM-5 may include one or more of a rare earth metal, a transition metal or an alkaline earth metal. The metal supported on ZSM-5 may also include one or more of La, Ce, Fe, Ca, Mg or phosphorus.

[0044] As previously mentioned, the SECC of two fractions can occur in a separate reactor. In these embodiments, the steam enhanced catalytic cracker 131 may include a first steam enhanced catalytic cracker and a second steam enhanced cracker. Each steam enhanced catalytic cracker can be fluidly connected to a hydroprocessing unit and can crack different liquid fractions. For example, in an embodiment, the first steam enhanced catalytic cracker can carry out SECC to a light liquid fraction 130, and the second steam enhanced catalytic cracker can carry out SECC to a heavy liquid fraction. Each of these crackers can in turn form a SECC product 140, which in turn can include a light SECC liquid product (from the first steam enhanced catalytic cracker) and a heavy SECC liquid product (from the second steam enhanced catalytic cracker). The first and second steam enhanced catalytic crackers can also be parallel to each other.

[0045] In an embodiment, the light liquid fraction 130 and the heavy liquid fraction 135 may need to be processed under different conditions in the steam enhanced catalytic cracker 131 to maximize the yield of the desired product. In one non-limiting example, the light liquid fraction 130 may require a longer residence time than the heavy liquid fraction 135 to fully process and convert the light components in the light liquid fraction 130. Additionally, the heavy liquid fraction 135 may require a shorter residence time to avoid excessive coking of components of the heavy liquid fraction 135.

[0046] The first steam enhanced catalytic cracker and the second steam enhanced catalytic cracker can also generate different hydrocarbon product distributions with their product streams. For example, the first steam enhanced catalytic cracker can generate a larger proportion of olefins compared to naphtha range products (including naphtha and gasoline). In embodiments, the first steam enhanced catalytic cracker can generate olefins and naphtha with an olefin to naphtha product ratio of about 3.3:1. The first steam enhanced catalytic cracker can also generate olefins and naphtha with an olefin to naphtha product ratio of 2:1, 3:1, 4:1, 5:1, 6:1 or 7:1.

[0047] Similarly, the second steam enhanced catalytic cracker can produce a greater proportion of naphtha and gasoline range products rather than olefins. In an embodiment, the second steam enhanced catalytic cracker can produce olefins and naphtha with an olefin to naphtha product ratio of 2.5: 1. The second steam enhanced catalytic cracker can also produce olefins and naphtha with an olefin to naphtha product ratio of 2.5: 1, 2: 1, 1.5: 1, 1: 1 or 0.8: 1.

[0048] In embodiments, the steam in the steam-enhanced catalytic cracker can reduce the partial pressure of hydrocarbon, which may have a dual effect on improving the output of light olefins and / or BTX hydrocarbons and reducing coking. Light olefins such as propylene and butene are mainly generated by the catalytic cracking reaction of the carbocation mechanism, and because these are intermediates, they can carry out secondary reactions (causing coking) such as hydrogen transfer and aromatization. Steam can improve the output of light olefins by suppressing these secondary bimolecular reactions, and reduce the concentration of reactants and products, which is conducive to the selectivity of light olefins. Steam can also suppress the secondary reaction that causes catalyst surface coking, which is conducive to catalyst keeping high average activation rate. These factors may indicate that larger steam and oil weight ratio may be beneficial to the production of light olefins.

[0049] In embodiments, improving steam to feed ratio can improve the light olefin production of steam enhanced catalytic cracker. The ratio of the steam flow rate (gas hourly space velocity) entering the steam enhanced catalytic cracker to the flow rate (gas hourly space velocity) of the feed (light liquid fraction or heavy liquid fraction) can be 0.1 times to 1.1 times, 0.1 times to 0.8 times, 0.1 times to 0.5 times, 0.1 times to 0.2 times, 0.2 times to 1.1 times, 0.2 times to 0.8 times, 0.2 times to 0.5 times, 0.3 times to 1.1 times, 0.3 times to 0.8 times, 0.3 times to 0.5 times, 0.5 times to 1.1 times, 0.5 times to 0.8 times or 0.8 times to 1.1 times of steam and feed, to improve the steam enhanced catalytic cracking process. The SECC steam / feed weight ratio can also be at least 0.3. For example, the SECC steam / feed ratio can also be 0.3wt.% to 1.0wt.% steam to feed. Alternatively, the SECC steam / feed weight ratio can be at least 0.2. For example, the SECC steam / feed ratio can be 0.2wt.% to 2.0wt.% steam to feed. The SECC product 140 can include light olefins, such as ethylene and propylene. For example, the SECC product 140 can include at least 20wt.% light olefins or 15wt.% to 60wt.% light olefins.

[0050] In embodiments, the ratio of steam to feed may be different for the first steam enhanced catalytic cracker and the second steam enhanced catalytic cracker. For example, the second steam enhanced catalytic cracker may have a steam feed ratio of 0.8 to 1.0 steam to feed, while the first steam enhanced catalytic cracker may have a steam feed ratio of 0.2 to 0.8. In embodiments, a higher steam feed ratio may be beneficial to heavy fractions because of the need to reduce the viscosity of heavier crude oil fractions and to atomize the heavy fractions.

[0051] In an embodiment, the steam may be heated at a rate of greater than or equal to 0.1 h. -1 , greater than or equal to 0.5h -1 , greater than or equal to 1h -1 , greater than or equal to 5h -1 , greater than or equal to 6h -1 , greater than or equal to 10h -1 Or even greater than or equal to 15h -1 The steam may be injected into the first and second steam enhanced catalytic crackers at a gas hourly space velocity of less than or equal to 100 h -1 , less than or equal to 75h -1 , less than or equal to 50h -1 , less than or equal to 30h -1 Or less than or equal to 20h -1 The steam can be introduced into the steam enhanced catalytic cracker at a gas hourly space velocity of 0.1 h -1 Until 100h-1 , 0.1h -1 Up to 75h -1 , 0.1h -1 Up to 50h -1 , 0.1h -1 Up to 30h -1 , 0.1h -1 Until 20h -1 , 1h -1 Until 100h -1 , 1h -1 Up to 75h -1 , 1h -1 Up to 50h -1 , 1h -1 Up to 30h -1 , 1h -1 Until 20h -1 , 5h -1 Until 100h -1 , 5h -1 Up to 75h -1 , 5h -1 Up to 50h -1 , 5h -1 Up to 30h -1 , 5h -1 Until 20h -1 , 6h -1 Until 100h -1 , 6h -1 Up to 75h -1 , 6h -1 Up to 50h -1 , 6h -1 Up to 30h -1 , 6h -1 Until 20h -1 , 10h -1 Until 100h -1 , 10h -1 Up to 75h -1 , 10h -1 Up to 50h -1 , 10h -1 Up to 30h -1 , 10h -1 Until 20h -1 , 15h -1 Until 100h -1 , 15h -1 Up to 75h -1 , 15h -1 Up to 50h -1 , 15h -1 Up to 30h -1 or 15h -1 Until 20h -1The gas hourly space velocity is introduced into the steam enhanced catalytic cracker.

[0052] In an embodiment, the feed (light liquid fraction or heavy liquid fraction) may be fed at a rate of greater than or equal to 0.1 h -1 ) or greater than or equal to 0.25h -1 The feed may be injected into the first and second steam enhanced catalytic crackers at a gas hourly space velocity of less than or equal to 50 h -1 , less than or equal to 25h -1 , less than or equal to 20h -1 , less than or equal to 14h -1 , less than or equal to 9h -1 Or less than or equal to 5h -1 The feed can be injected into the steam enhanced catalytic cracker at a gas hourly space velocity of 0.1 h -1 Up to 50h -1 , 0.1h -1 Until 25h -1 , 0.1h -1 Until 20h -1 , 0.1h -1 Until 14h -1 , 0.1h -1 Until 9h -1 , 0.1h -1 Until 5h -1 , 0.1h -1 Up to 4h -1 , 0.25h -1 Up to 50h -1 , 0.25h -1 Until 25h -1 , 0.25h -1 Until 20h -1 , 0.25h -1 Until 14h -1 , 0.25h -1 Until 9h -1 , 0.25h -1 Until 5h -1 , 0.25h -1 Up to 4h -1 , 1h -1 Up to 50h -1 , 1h -1 Until 25h -1 , 1h -1 Until 20h -1 , 1h -1 Until 14h -1 , 1h -1 Until 9h -1 or 1h -1 Until 5h -1The gas hourly space velocity is injected into the steam enhanced catalytic cracker.

[0053] In an embodiment, the hourly space velocity may be different for the first steam enhanced catalytic cracker compared to the second steam enhanced catalytic cracker. In one non-limiting example, the light liquid fraction may require a lower hourly space velocity to provide more time for the light liquid fraction to crack into the desired products. In another non-limiting example, the heavy liquid fraction may require a higher hourly space velocity to prevent over-cracking of the heavy liquid fraction and prevent excessive formation of petroleum coke. In an embodiment, the hourly space velocity of the first steam enhanced catalytic cracker may be 0.1h 2. -1 Up to 1h -1 In an embodiment, the hourly space velocity of the second steam enhanced catalytic cracker may be 9h -1 Up to 40h -1 .

[0054] In embodiments, the first steam enhanced catalytic cracker and the second steam enhanced catalytic cracker may be operated at a temperature greater than or equal to 525°C, greater than or equal to 550°C, or greater than or equal to 575°C. The steam enhanced catalytic cracker 114 may be operated at a temperature less than or equal to 750°C, less than or equal to 675°C, less than or equal to 650°C, or even less than or equal to 625°C. The steam enhanced catalytic cracker 114 may be operated at a temperature of 650°C to 750°C or 675°C to 750°C. The steam enhanced catalytic cracker 114 may be operated at a temperature of 525°C to 750°C, 525°C to 675°C, 525°C to 650°C, 525°C to 625°C, 550°C to 675°C, 550°C to 650°C, 550°C to 625°C, 575°C to 675°C, 575°C to 650°C, or 575°C to 625°C. In other embodiments, the SECC temperature may be from 600° C. to 750° C. For example, the SECC temperature may be from 600° C. to 700° C. or from 620° C. to 680° C. The steam enhanced catalytic cracker 114 may operate at a pressure of from 0.1 MPa to 0.2 MPa.

[0055] As previously mentioned, the steam enhanced catalytic cracker 114 can produce olefins, particularly light olefins, such as ethylene, propylene and butene. In embodiments, the steam enhanced catalytic cracker can additionally produce gasoline as olefins. In embodiments, the ratio of the olefins (gasoline) produced to the light olefins can be changed according to the operating temperature used in the steam enhanced catalytic cracker 114. For example, the operating temperature between 500°C and 650°C can mainly produce propylene and gasoline, rather than ethylene. As the operating temperature increases, the ratio rises further, mainly producing ethylene, rather than propylene and gasoline. For example, the operating temperature between 650°C and 680°C can produce equal parts of ethylene and propylene and less gasoline. At operating temperatures exceeding 680°C, such as 680°C to 750°C, the reaction mainly produces ethylene.

[0056] In embodiments, temperatures at the higher end of the operating range (>650°C) can be used to preferentially produce light olefins rather than heavy olefins, such as ethylene and propylene rather than gasoline. Thus, this may make gasoline a byproduct of the steam enhanced catalytic cracking reaction compared to the main product. Further temperature increases (>680°C) may then minimize the amount of gasoline produced, producing primarily ethylene and propylene as byproducts. It is expected that the above changes may be related to reactions in the steam enhanced catalytic cracker, which are primarily catalytic cracking at lower temperatures (500°C to 650°C) to primarily thermal cracking at higher end operating temperatures (>680°C).

[0057] Steam cracking product 121, dehydrogenation stream 126 and SECC product 140 can be fractionated to form light olefin stream 170 and benzene-toluene-xylene (BTX) stream 180. The stream can be fractionated in product separator 165. Light olefin stream 170 can contain light olefins, such as ethylene, propylene and butene. Light olefin stream 170 can contain at least 70wt.%, at least 80wt.%, at least 90wt.%, at least 95wt.%, at least 99wt.% or at least 99.9wt.% of light olefins, such as ethylene, propylene and butene. BTX stream 180 can contain aromatic compounds, such as benzene, toluene and xylene. For example, BTX stream 180 can contain at least 70wt.%, at least 80wt.%, at least 90wt.%, at least 95wt.%, at least 99wt.% or at least 99.9wt.% of aromatic compounds.

[0058] Example

[0059] according to Figure 1 and Figure 2The systems / configurations in the FIG. 1000 were used to process Arab Heavy Crude Oil and Arab Very Light Crude Oil using computer models using Aspen HYSYS simulation software. The reaction conditions used in the two systems are shown in Table 1 below. The compositions of the Arab Heavy Crude Oil and Arab Very Light Crude Oil feeds are shown in Table 2 below.

[0060] As used herein, "T'x' boiling point" refers to the temperature at which about x% of the components in the crude oil boil. For example, "T5 boiling point" refers to the temperature at which about 5% of the components in the crude oil boil. This measurement can also be used to determine the percentage of feed that boils below a given temperature. For example, if the T5 and T10 boiling points of Arab Heavy Crude Oil are 56°C and 103°C, respectively, then the Arab Heavy Crude Oil may include approximately 5% of hydrocarbon fractions with boiling points below 56°C and approximately 5% of hydrocarbon fractions with boiling points between 56°C and 103°C.

[0061] Table 1: Operating conditions

[0062]

[0063] Table 2: Feed composition

[0064]

[0065] Example 1

[0066] As mentioned above, Figure 1 Computer model of the system entering Arabian heavy crude oil as feed. The simulation results are given in Table 3 below. The total production is the sum of the output of each of the following processing units.

[0067] Table 3

[0068]

[0069] As shown in Table 3, the system obtains a yield of nearly 50wt.% light olefins without BTX. Although by-product naphtha and synthesis gas account for 37wt.% of the output, each can be further used in other processes or further upgraded in the recycle stream of the system. For example, naphtha can be recycled back through a steam cracker to further upgrade naphtha to additional light olefins. If naphtha is treated in an aromatization unit (including, for example, a catalytic reformer and an alkyl transfer unit), it can also be further upgraded to BTX. Synthesis gas can also be used to provide energy to other processing units in the form of heat. For example, synthesis gas can be used to heat water to be used as steam in a steam cracker or a steam enhanced catalytic cracker. The hydrogen in the gasification unit can also be used in a hydroprocessing or hydrocracking unit.

[0070] In Table 4 above, "Others" may include crude oil fractions not mentioned in the above components. Others may also include waste or unusable streams. For example, Others may include light cycle oil, heavy cycle oil, distillate oil, and C 1 and C 2 -C 4 Heavy cycle oil can be used as fuel oil for boilers, for example.

[0071] Example 2

[0072] As mentioned above, Figure 2 Computer model of the system entering Arabian Super Light Crude Oil as feed. The simulation results are given in Table 4 below. The total production is the sum of the output of each of the following processing units.

[0073] Table 4

[0074]

[0075]

[0076] As shown in Table 4, the system obtains a yield of 61.5 wt.% of light olefins, which is almost BTX. Although by-product naphtha and synthesis gas account for nearly 34 wt.% of the yield, each of them can be further used in other processes or further upgraded in the recycle stream of the system, as described above. Naphtha in particular can be further upgraded, such as in an aromatization unit, to upgrade naphtha to BTX.

[0077] It should also be noted that references herein to “at least one” of a component, element, etc. should not be used to infer that the alternative use of the article “a” or “an” should be limited to only a single component, element, etc.

[0078] Having described the subject matter of the present disclosure in detail and with reference to specific embodiments thereof, it should be noted that the various details described herein should not be viewed as implying that these details relate to elements that are essential parts of the various embodiments described herein, even in the case where specific elements are shown in each of the drawings accompanying this specification. Moreover, it will be apparent that modifications and variations are possible without departing from the scope of the present disclosure, including but not limited to the embodiments defined in the appended claims. More specifically, although some aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these aspects.

[0079] A first aspect may include a method for converting a petroleum feedstock into light olefins, the method comprising: pretreating a petroleum feedstock to form one or more pretreated petroleum feedstocks; fractionating the one or more pretreated petroleum feedstocks to form a methane stream, an ethane stream, a C 3 -C4 stream, a light liquid fraction and a heavy liquid fraction; methane cracking a methane stream to form hydrogen; steam cracking an ethane stream to form a steam cracking product; making C 3 -C 4 dehydrogenating the stream to form a dehydrogenated stream; and performing steam enhanced catalytic cracking (SECC) on the light liquid fraction and the heavy liquid fraction to form a SECC product.

[0080] A second aspect may include any of the preceding aspects, wherein pretreating the petroleum feed comprises solvent deasphalting the petroleum feed.

[0081] A third aspect may include the second aspect, wherein solvent deasphalting the petroleum feed comprises contacting the petroleum feed with a solvent at a temperature of 120°C to 160°C, a pressure of 2 MPa to 6 MPa, and a solvent / feed ratio of 3-6.

[0082]

[0013] A fourth aspect may include any of the preceding aspects, wherein pretreating the petroleum feed comprises gasifying an asphaltene stream.

[0083]

[0013] A fifth aspect may include the fourth aspect, wherein gasifying the asphaltene stream comprises exposing the asphaltene stream to a temperature of 700°C to 1200°C and a pressure of 1 bar to 29 bar.

[0084]

[0013] A sixth aspect may include any of the preceding aspects, wherein pretreating the petroleum feed comprises hydrotreating a deasphalted oil stream.

[0085] The seventh aspect may include the sixth aspect, wherein the hydroprocessing is hydrofinishing, and hydrofinishing the deasphalted oil stream comprises contacting the deasphalted oil stream with a hydrogen stream at a temperature of 280°C to 450°C and a pressure of 5 bar to 160 bar.

[0086] An eighth aspect may include any of the preceding aspects, further comprising fractionating the steam cracking product, the dehydrogenation stream, and the SECC product to form a light olefin stream and a benzene-toluene-xylene (BTX) stream.

[0087] A ninth aspect may include any of the preceding aspects, further comprising: methane cracking the methane recycle stream; steam cracking the steam cracking recycle stream; and dehydrogenating the dehydrogenation recycle stream.

[0088] A tenth aspect may include any of the preceding aspects, wherein the petroleum feed is whole crude oil.

[0089] An eleventh aspect may include any of the preceding aspects, wherein the whole crude oil is Arabian extra light oil, Arabian light oil, or Arabian heavy oil.

[0090] A twelfth aspect may include any of the preceding aspects, wherein: the light liquid fraction comprises C 5hydrocarbons; and the heavy liquid fraction comprises hydrocarbons having a cut point of at least 300°C.

[0091] A thirteenth aspect may include any of the preceding aspects, wherein SECC comprises contacting the hydrocarbon with the catalyst at a reaction temperature of 600°C to 750°C.

[0092] A fourteenth aspect may include any of the preceding aspects, wherein the SECC comprises contacting the hydrocarbon with the catalyst at a steam to feed weight ratio of 0.3 to 1.0.

[0093] A fifteenth aspect may include any of the preceding aspects, wherein SECC comprises contacting a hydrocarbon with a ZSM-5 based catalyst.

[0094] A sixteenth aspect may include any of the preceding aspects, wherein C 3 -C 4 The dehydrogenation of the C 3 -C 4 The stream is contacted with a dehydrogenation catalyst at a temperature of 575°C to 620°C and a pressure of 2 bar to 5 bar.

[0095] A seventeenth aspect may include any of the preceding aspects, further comprising fractionating a petroleum feed to produce a light crude fraction, and steam enhanced catalytic cracking the light crude fraction.

[0096] An eighteenth aspect may include a system for converting a petroleum feedstock into light olefins, the system comprising: a pretreatment complex configured to pretreat the petroleum feedstock to form one or more pretreated petroleum feedstocks; a separator fluidly connected to the pretreatment complex and configured to fractionate the one or more pretreated petroleum feedstocks to form a methane stream, an ethane stream, a C 3 -C 4 a methane cracker fluidly connected to the separator and configured to methane crack the methane stream to form hydrogen; a steam cracker fluidly connected to the separator and configured to steam crack the ethane stream to form a steam cracked product; a dehydrogenation unit fluidly connected to the separator and configured to make C 3 -C 4 The stream is dehydrogenated to form a dehydrogenated stream; and one or more steam enhanced catalytic crackers fluidly connected to the separator and configured to steam enhanced catalytic crack the light liquid fraction and the heavy liquid fraction to form steam enhanced catalytic cracking products.

[0097] The nineteenth aspect may include the eighteenth aspect, wherein the pretreatment complex further comprises: a solvent deasphalting unit; a gasification unit; and a hydroprocessing unit.

[0098] The twentieth aspect may include the eighteenth aspect or the nineteenth aspect, and further includes a product separator, wherein: the product separator fluid is connected to a steam cracker, a dehydrogenation unit, one or more steam-enhanced catalytic crackers and a pretreatment complex; and the product separator is configured to fractionate the steam cracking products, the dehydrogenation stream 126 and the steam-enhanced catalytic cracking products to form a light olefin stream and a benzene-toluene-xylene (BTX) stream.

[0099] It should be noted that one or more of the following claims utilize the term "wherein" as a transitional phrase. For purposes of defining the present invention, it should be noted that this term is introduced in the claims as an open transitional phrase used to introduce a recitation of a series of features of a structure and should be interpreted in a manner similar to the more commonly used open-ended term "comprising."

Claims

1. A method for converting a petroleum feedstock into light olefins, the method comprising: pretreating the petroleum feed to form one or more pretreated petroleum feeds; fractionating the one or more pretreated petroleum feeds to form a methane stream, an ethane stream, a C3-C4 stream, a light liquid fraction, and a heavy liquid fraction; methane cracking the methane stream to form hydrogen; steam cracking the ethane stream to form a steam cracked product; dehydrogenating the C3-C4 stream to form a dehydrogenated stream; and The light liquid fraction and the heavy liquid fraction are subjected to steam enhanced catalytic cracking (SECC) to form a SECC product.

2. The method of claim 1, wherein pretreating the petroleum feed comprises solvent deasphalting the petroleum feed, comprising contacting the petroleum feed with a solvent at a temperature of 120-160°C, a pressure of 2-6 MPa, and a solvent / feed ratio of 3-6.

3. The method according to any one of the preceding claims, wherein pre-treating the petroleum feed comprises gasifying an asphaltene stream, comprising exposing the asphaltene stream to a temperature of 700°C to 1200°C and a pressure of 1 bar to 29 bar.

4. The method according to any one of the preceding claims, wherein pre-treating the petroleum feed comprises hydrotreating a deasphalted oil stream comprising contacting the deasphalted oil stream with a hydrogen gas stream at a temperature of 280° C. to 450° C. and a pressure of 5 bar to 160 bar.

5. The method according to any one of the preceding claims, further comprising fractionating the steam cracking product, the dehydrogenation stream and the SECC product to form a light olefin stream and a benzene-toluene-xylene (BTX) stream.

6. The method according to any one of the preceding claims, further comprising: performing methane cracking on the methane recycle stream; steam cracking the steam cracking recycle stream; as well as The dehydrogenation recycle stream is dehydrogenated.

7. The method according to any one of the preceding claims, wherein the petroleum feed is a whole crude oil selected from one or more of Arabian Extra Light Oil, Arabian Light Oil or Arabian Heavy Oil.

8. A method according to any one of the preceding claims, wherein: The light liquid fraction contains C5 hydrocarbons having a cut point of up to 300° C.; and The heavy liquid fraction comprises hydrocarbons having a cut point of at least 300°C.

9. The process according to any one of the preceding claims, wherein SECC comprises contacting the light liquid fraction and the heavy liquid fraction with a catalyst at a reaction temperature of 600°C to 750°C, a steam / feed weight ratio of 0.3 to 1.0, or both.

10. A process according to any one of the preceding claims, wherein SECC comprises contacting the hydrocarbon with a ZSM-5 based catalyst.

11. The method according to any one of the preceding claims, wherein dehydrogenating the C3-C4 stream comprises contacting the C3-C4 stream with a dehydrogenation catalyst at a temperature of 575°C to 620°C and a pressure of 2 bar to 5 bar.

12. The method of any one of the preceding claims, further comprising fractionating the petroleum feed to produce a light crude fraction, and steam enhanced catalytic cracking the light crude fraction.

13. A system for converting a petroleum feedstock into light olefins, the system comprising: a pretreatment complex configured to pretreat a petroleum feed to form one or more pretreated petroleum feeds; a separator fluidly connected to the pretreatment complex and configured to fractionate the one or more pretreated petroleum feeds to form a methane stream, an ethane stream, a C3-C4 stream, a light liquid fraction, and a heavy liquid fraction; a methane cracker fluidly connected to the separator and configured to methane crack the methane stream to form hydrogen; a steam cracker fluidly connected to the separator and configured to steam crack the ethane stream to form a steam cracked product; a dehydrogenation unit fluidly connected to the separator and configured to dehydrogenate the C3-C4 stream to form a dehydrogenated stream; and One or more steam enhanced catalytic crackers are fluidly connected to the separator and are configured to steam enhanced catalytic crack the light liquid fraction and the heavy liquid fraction to form steam enhanced catalytic cracking products.

14. The system of claim 13, wherein the pre-processing complex further comprises: Solvent deasphalting unit; Gasification unit; and Hydroprocessing unit.

15. The system of any one of claims 13 or 14, further comprising a product separator, wherein: The product separator is fluidly connected to the steam cracker, the dehydrogenation unit, the one or more steam enhanced catalytic crackers, and the pretreatment complex; and The product separator is configured to fractionate the steam cracking products, the dehydrogenation stream 126, and the steam enhanced catalytic cracking products to form a light olefin stream and a benzene-toluene-xylene (BTX) stream.

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