CN110937969B - Device and process for producing paraxylene - Google Patents
Device and process for producing paraxylene Download PDFInfo
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- CN110937969B CN110937969B CN201811113917.7A CN201811113917A CN110937969B CN 110937969 B CN110937969 B CN 110937969B CN 201811113917 A CN201811113917 A CN 201811113917A CN 110937969 B CN110937969 B CN 110937969B
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- URLKBWYHVLBVBO-UHFFFAOYSA-N Para-Xylene Chemical group CC1=CC=C(C)C=C1 URLKBWYHVLBVBO-UHFFFAOYSA-N 0.000 title claims abstract description 152
- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000006317 isomerization reaction Methods 0.000 claims abstract description 151
- 238000000926 separation method Methods 0.000 claims abstract description 108
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 claims abstract description 102
- 238000001179 sorption measurement Methods 0.000 claims abstract description 97
- 239000008096 xylene Substances 0.000 claims abstract description 90
- 238000005194 fractionation Methods 0.000 claims abstract description 45
- 239000004927 clay Substances 0.000 claims abstract description 31
- 238000010438 heat treatment Methods 0.000 claims abstract description 31
- 239000007788 liquid Substances 0.000 claims abstract description 15
- 239000000463 material Substances 0.000 claims description 144
- 239000000047 product Substances 0.000 claims description 61
- 150000004945 aromatic hydrocarbons Chemical class 0.000 claims description 38
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 30
- 229930195733 hydrocarbon Natural products 0.000 claims description 21
- 150000002430 hydrocarbons Chemical class 0.000 claims description 21
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 20
- 229910052739 hydrogen Inorganic materials 0.000 claims description 20
- 239000001257 hydrogen Substances 0.000 claims description 20
- 239000004215 Carbon black (E152) Substances 0.000 claims description 17
- 239000007795 chemical reaction product Substances 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 13
- 238000007599 discharging Methods 0.000 claims description 12
- 239000002994 raw material Substances 0.000 claims description 11
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 238000010992 reflux Methods 0.000 claims description 6
- 229930195735 unsaturated hydrocarbon Natural products 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 3
- 238000004064 recycling Methods 0.000 claims description 3
- 125000003944 tolyl group Chemical group 0.000 claims description 2
- 238000010977 unit operation Methods 0.000 claims description 2
- 238000005265 energy consumption Methods 0.000 abstract description 10
- 230000008901 benefit Effects 0.000 abstract description 9
- 239000002737 fuel gas Substances 0.000 abstract description 8
- 238000004519 manufacturing process Methods 0.000 description 8
- 238000001816 cooling Methods 0.000 description 7
- 239000002808 molecular sieve Substances 0.000 description 6
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 239000003463 adsorbent Substances 0.000 description 4
- 150000001336 alkenes Chemical class 0.000 description 4
- WOZVHXUHUFLZGK-UHFFFAOYSA-N dimethyl terephthalate Chemical compound COC(=O)C1=CC=C(C(=O)OC)C=C1 WOZVHXUHUFLZGK-UHFFFAOYSA-N 0.000 description 4
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 4
- 239000012071 phase Substances 0.000 description 4
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 description 3
- 230000000274 adsorptive effect Effects 0.000 description 3
- 125000003118 aryl group Chemical group 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- DSNHSQKRULAAEI-UHFFFAOYSA-N 1,4-Diethylbenzene Chemical compound CCC1=CC=C(CC)C=C1 DSNHSQKRULAAEI-UHFFFAOYSA-N 0.000 description 2
- 150000001335 aliphatic alkanes Chemical class 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 150000001924 cycloalkanes Chemical class 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910052809 inorganic oxide Inorganic materials 0.000 description 2
- IVSZLXZYQVIEFR-UHFFFAOYSA-N m-xylene Chemical group CC1=CC=CC(C)=C1 IVSZLXZYQVIEFR-UHFFFAOYSA-N 0.000 description 2
- -1 olefin and the like Natural products 0.000 description 2
- 238000005192 partition Methods 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- OCJBOOLMMGQPQU-UHFFFAOYSA-N 1,4-dichlorobenzene Chemical compound ClC1=CC=C(Cl)C=C1 OCJBOOLMMGQPQU-UHFFFAOYSA-N 0.000 description 1
- 239000005995 Aluminium silicate Substances 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- GMSCBRSQMRDRCD-UHFFFAOYSA-N dodecyl 2-methylprop-2-enoate Chemical compound CCCCCCCCCCCCOC(=O)C(C)=C GMSCBRSQMRDRCD-UHFFFAOYSA-N 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000005984 hydrogenation reaction Methods 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical group O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 229910052680 mordenite Inorganic materials 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 238000002407 reforming Methods 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
- C07C5/22—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by isomerisation
- C07C5/27—Rearrangement of carbon atoms in the hydrocarbon skeleton
- C07C5/2702—Catalytic processes not covered by C07C5/2732 - C07C5/31; Catalytic processes covered by both C07C5/2732 and C07C5/277 simultaneously
- C07C5/2708—Catalytic processes not covered by C07C5/2732 - C07C5/31; Catalytic processes covered by both C07C5/2732 and C07C5/277 simultaneously with crystalline alumino-silicates, e.g. molecular sieves
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C15/00—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts
- C07C15/02—Monocyclic hydrocarbons
- C07C15/067—C8H10 hydrocarbons
- C07C15/08—Xylenes
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
- C07C5/22—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by isomerisation
- C07C5/27—Rearrangement of carbon atoms in the hydrocarbon skeleton
- C07C5/2702—Catalytic processes not covered by C07C5/2732 - C07C5/31; Catalytic processes covered by both C07C5/2732 and C07C5/277 simultaneously
- C07C5/2724—Catalytic processes not covered by C07C5/2732 - C07C5/31; Catalytic processes covered by both C07C5/2732 and C07C5/277 simultaneously with metals
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/005—Processes comprising at least two steps in series
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/04—Purification; Separation; Use of additives by distillation
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/12—Purification; Separation; Use of additives by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers
- C07C7/13—Purification; Separation; Use of additives by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers by molecular-sieve technique
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
The invention discloses a device and a process for producing paraxylene. The device for producing the paraxylene comprises a xylene fractionation unit, an adsorption separation unit and an isomerization reaction unit; the adsorption separation unit comprises an adsorption separation tower, an extract liquid fractionating tower, a raffinate tower and a heat exchanger II; the isomerization reaction unit comprises an isomerization reactor, an isomerization product fractionating tower, a clay tower, an isomerization reaction heating furnace, a heat exchanger III, a heat exchanger IV, a heat exchanger V and a compressor. The invention also provides a process for producing the paraxylene. The invention reduces the equipment investment and the occupied area, reduces the operation load of the xylene tower, saves the fuel gas consumption of the xylene reboiling furnace and the isomerization reaction heating furnace, optimizes the heat exchange network, greatly reduces the energy consumption and improves the economic benefit and the social benefit.
Description
Technical Field
The invention relates to a device and a process for producing paraxylene.
Background
Paraxylene is one of important basic organic raw materials in petrochemical industry, is mainly used for Preparing Terephthalic Acid (PTA) and dimethyl terephthalate (DMT), and is widely applied to the production fields of chemical fibers, synthetic resins, pesticides, medicines, plastics and the like. 2017. The apparent consumption of p-xylene in China can reach 2400 multiplied by 10 4 t, the productivity of the paraxylene device reaches 816 multiplied by 10 4 t, the production capacity of the whole world is about 20 percent, and China is the biggest paraxylene producing country in the world.
C 8 Aromatic hydrocarbons include the four isomers of ortho-, para-, meta-and ethylbenzene, with para-xylene being the largest in the marketplace, and so it is generally more desirable in the industry to enhance the conversion of the aromatic hydrocarbon to the specified C 8 The aromatic feedstock source even maximizes the production of para-xylene. Due to their chemical structure andsimilar physical properties and molecular weight, and is generally used for the isomerization reaction to dilute the para-xylene C 8 Conversion of aromatics to equilibrium concentration C 8 Aromatic hydrocarbon mixture is rectified, adsorbed and separated to obtain high purity p-xylene product and low p-xylene C 8 The aromatic hydrocarbon is circulated in the system to carry out isomerization reaction again.
The separation of paraxylene is generally carried out industrially by crystallization and adsorption separation, and the adsorption separation is used in many cases. The raw material for adsorption separation is mixed C 8 Aromatic hydrocarbons, using para-C 8 The selectivity of four isomers of aromatic hydrocarbon is different, para-xylene is preferentially adsorbed, and then the para-xylene on the adsorbent is desorbed by a desorbent. The extract is a material rich in p-xylene, and a high-purity p-xylene product is obtained by rectification; the raffinate is a material poor in p-xylene, and after a desorbent is separated out by a raffinate tower, the C with the equilibrium concentration is obtained through isomerization reaction 8 The aromatic mixture is then recycled back to the xylene for fractionation. In the process, the extract is rectified into an extract tower and a finished product tower double-tower flow, the energy consumption is large, and C in the isomerized product is removed by a deheptanizer 7 After the light hydrocarbon is discharged, most of the light hydrocarbon is circulated back to the xylene tower, so that the operation load of the xylene tower is increased, and the fuel consumption of the xylene reboiling furnace is increased. Meanwhile, the isomerization product and the feeding material are cooled completely after heat exchange, and are reheated after hydrogen is separated, so that the phenomenon of unreasonable energy utilization exists.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a device and a process for producing paraxylene, which reduce equipment investment and floor area, reduce the operation load of a xylene tower, save the fuel gas consumption of a xylene reboiling furnace and an isomerization reaction heating furnace, optimize a heat exchange network, greatly reduce energy consumption and improve economic benefit and social benefit.
The device for producing the paraxylene comprises a xylene fractionation unit, an adsorption separation unit and an isomerization reaction unit;
the xylene fractionation unit comprises a xylene tower, a heat exchanger I and a xylene reboiling furnace.
The xylene column is used for separating C 8 Component (A) and (C) 9 + The component is generally a plate-type rectifying tower.
The heat exchanger I is used for taking the xylene overhead material flow as a heat source of a reboiler of the raffinate tower and a reboiler of the extract fractionating tower, one part of the condensate after heat exchange is used as reflux and returns to the xylene tower, and the other part of the condensate after heat exchange is used as adsorption separation feeding.
The xylene reboiling furnace is used for heating materials which are circulated to the bottom of the xylene reboiling furnace so as to provide reboiling heat for the xylene reboiling tower.
Said xylene fractionation unit further comprising a unit for fractionating a fraction containing C 8 The aromatic hydrocarbon mixture raw material is fed into a feed pipeline of the xylene tower; a pipeline for sending the tower top discharge to a heat exchanger I; circulating a part of the discharged material at the top of the tower after heat exchange by the heat exchanger I back to a pipeline of the xylene tower; the other part of the discharged material at the top of the tower after the heat exchange of the heat exchanger I is sent to a pipeline of the adsorption separation unit; a feed line for feeding a portion of the bottoms to a bottom reboiling furnace; a line for recycling the bottom material heated by the bottom reboiling furnace to the xylene column; the other part of the tower bottom material is discharged out of a pipeline of the xylene tower; wherein the top discharge of the tower is C 8 Aromatic hydrocarbon, the material at the bottom of the tower is C 9 + An aromatic hydrocarbon.
The adsorption separation unit comprises an adsorption separation tower, an extract liquid fractionating tower, a raffinate tower and a heat exchanger II.
The adsorption separation tower is used for separating paraxylene and isomers thereof in materials from a xylene fractionation unit.
The extract fractionating tower is used for separating toluene, paraxylene and desorbent in the extract rich in paraxylene to obtain a high-purity paraxylene product. The extract fractionating tower adopts a dividing wall tower, the material at the bottom of the tower is a desorbent, the material at the top of the tower is toluene, and the material at the side line is a paraxylene product.
The raffinate tower is used for separating C in the p-xylene-poor raffinate 8 The components and the desorbent are discharged from the upper side line of the raffinate tower as the lean p-xylene C 8 The components, the discharge from the bottom of the tower is the desorbent.
The heat exchanger II is used for exchanging heat between a desorbent and an isomerization feed, improving the temperature of the isomerization feed and reducing the load of an isomerization reaction heating furnace; and simultaneously reducing the temperature of the desorbent to the proper temperature for returning to the adsorption separation tower.
The adsorption separation unit also comprises a pipeline for feeding the tower top discharge of the xylene fractionation unit after heat exchange to an adsorption separation tower, a pipeline for delivering the separated p-xylene-rich extract to an extract fractionation tower, and a pipeline for delivering the p-xylene-poor raffinate obtained by adsorption separation of the adsorption separation tower to a raffinate tower; a pipeline for discharging the materials at the top of the extract fractionating tower and a pipeline for discharging the materials at the side line of the extract fractionating tower; the method comprises the following steps of (1) sending an extract fractionating tower bottom material to a pipeline of a heat exchanger II, sending a raffinate tower bottom material (desorbent) to a pipeline of the heat exchanger II, and sending the extract fractionating tower bottom material and the raffinate tower bottom material subjected to heat exchange to a pipeline of an adsorption separation tower; and (3) feeding the side line discharge at the upper part of the raffinate tower to a pipeline of an isomerization reaction unit after heat exchange of a heat exchanger II.
The isomerization reaction unit comprises an isomerization reactor, an isomerization product fractionating tower, a clay tower, an isomerization reaction heating furnace, a heat exchanger III, a heat exchanger IV, a heat exchanger V and a compressor.
The isomerization reactor is used for separating the lean p-xylene C from the adsorption separation unit 8 Conversion of the component into para-xylene-rich C 8 And (4) components.
The isomerization product fractionating tower is used for separating the isomerization reactor discharge rich in the paraxylene C 8 C in component (A) 7 Lower light hydrocarbon, C 8 Aromatic hydrocarbons and C 9 The aromatic hydrocarbon component and the isomerized product fractionating tower adopts a dividing wall tower form, wherein the material at the top of the tower is mainly C 7 The bottom material of the tower is mainly C 9 + aromatic fraction, side stream mainly C 8 An aromatic hydrocarbon.
The isomerization reaction unit and the hydrogen come from the reforming unit. The proper hydrogen to hydrocarbon ratio is beneficial to maintaining the activity and stability of the isomerization catalyst. The clay tower is used for removing a small amount of unsaturated hydrocarbons such as olefin and carbonyl in the side line material of the isomerization product fractionating tower.
The isomerization heating furnace is used for controlling the isomerization feeding temperature.
The heat exchanger III is used for exchanging heat between the feed of the adsorption separation tower and the feed of the isomerization reaction, so that the isomerization feed temperature is increased, and the load of the isomerization reaction heating furnace is reduced. And simultaneously reducing the feeding temperature of the adsorption separation tower to a proper temperature.
The heat exchanger IV is used for isomerizing the feed and the isomerization reaction product (rich in p-xylene C) 8 Component), further improves the isomerization feeding temperature and reduces the load of an isomerization reaction heating furnace.
The heat exchanger V is used as an isomerization product fractionating tower side line material (C) of clay tower feeding 8 Aromatic hydrocarbon) and the clay tower discharge heat exchange, and the clay tower discharge temperature is increased; and mixing the clay tower discharge after heat exchange with the material after heat exchange on the top of the xylene tower, and taking the mixture as the feed of the adsorption separation tower to further separate out the paraxylene.
The compressor is used for pressurizing hydrogen entering the isomerization reactor.
The isomerization reaction unit also comprises a feed pipeline for feeding the isomerization reaction to the isomerization reactor, and the feed pipeline is sequentially connected with a heat exchanger III, a heat exchanger IV and an isomerization reaction heating furnace before being connected with the isomerization reactor; a feed line for feeding the isomerized product to the isomerized product fractionation column, the feed line being connected to the heat exchanger IV before being connected to the isomerized product fractionation column; fractionating the isomerization product into a column overhead material C 7 A discharge line for discharging the light hydrocarbon and hydrogen; feeding the side-line material of the isomerization product fractionating tower into a feeding pipeline of the clay tower, wherein the feeding pipeline is connected with a heat exchanger V in front of the clay tower; a discharge pipeline for discharging the product at the bottom of the carclazyte tower, wherein the discharge pipeline is sequentially connected with a heat exchanger V and an adsorption separation feed pipeline; a discharge line for discharging the isomerized product fractionation column bottoms; the hydrogen enters a compressor through a feeding pipeline to be pressurized, and an outlet pipeline of the compressor is connected with a feeding pipeline of an isomerization reaction rectification fractionating tower and is mixed with isomerization feeding materials.
The invention also provides a process for producing paraxylene, which comprises the following steps: containing C 8 The aromatic hydrocarbon mixture raw material enters a xylene tower for fractionation, after heat exchange is carried out on the tower top material by a heat exchanger I, one part of the tower top material is returned to the xylene tower as reflux, the other part of the tower top material is used as adsorption separation feeding material, and after heat exchange is carried out on the tower top material and isomerization reaction feeding material by a heat exchanger III, the tower top material is sent to an adsorption separation tower; one part of material flow at the bottom of the xylene tower is heated by a xylene reboiling furnace and then returns to the xylene tower, and the other part of material at the bottom of the xylene tower is C 9 + Aromatic hydrocarbons; the adsorption separation feeding is subjected to adsorption separation by an adsorption separation tower, the obtained p-xylene-rich extract enters an extract fractionating tower for fractionation, the tower bottom material is a desorbent, and after being mixed with the raffinate tower bottom material, the desorbent exchanges heat with the isomerization reaction feeding by a heat exchanger II and returns to the adsorption separation tower; toluene is taken as a material at the top of the extract fractionating tower, and paraxylene is taken as a material at the side line; the method comprises the following steps that a poor p-xylene raffinate obtained by adsorption separation in an adsorption separation tower enters a raffinate tower for fractionation, an upper side line material sequentially flows through a heat exchanger II, a heat exchanger III and a heat exchanger IV to exchange heat with a desorbent, an adsorption separation feed and an isomerization reaction product respectively, then the poor p-xylene raffinate enters an isomerization reactor for isomerization reaction after being heated by an isomerization reaction heating furnace, and the reaction product enters an isomerization product fractionating tower after being subjected to heat exchange in the heat exchanger IV; the overhead material of the isomerization product fractionating tower is used as C 7 Light hydrocarbon and hydrogen; the side line material of the isomerization product fractionating tower exchanges heat through a heat exchanger V, enters a clay tower to remove unsaturated hydrocarbons such as olefin and the like, exchanges heat with the feed of the clay tower to be used as adsorption separation feed, and the bottom discharge of the isomerization product fractionating tower is C 9 + An aromatic hydrocarbon.
The extract fractionating tower and the isomerized product fractionating tower are in the form of dividing wall towers, generally a vertical partition plate is arranged in the middle of a traditional rectifying tower, and the rectifying tower is divided into an upper public rectifying section, a lower public stripping section, a rectifying feeding section and a side line extracting section which are separated by the partition plate.
Said C containing 8 The aromatic hydrocarbon raw material mainly comprises mixed hydrocarbon containing ethylbenzene, paraxylene, ortho-xylene and meta-xylene, and also comprises C 7 Light hydrocarbons and C 9 The above heavy hydrocarbons. Wherein C is 7 The light hydrocarbon refers to hydrocarbon such as aromatic hydrocarbon, alkane or cycloalkane having 7 or less carbon atoms, C 9 The heavy hydrocarbon refers to a hydrocarbon having 9 or more carbon atoms, such as an aromatic hydrocarbon, an alkane, or a cycloalkane.
The top pressure of the xylene tower is 0.3 to 2.5 MPa, preferably 0.5 to 1.8 MPa, and the tower top temperature is 50 to 300 ℃, preferably 110 to 280 ℃. The xylene column is preferably a plate column, and the number of plates is 150 to 200.
The operating conditions of the adsorption separation unit are as follows: the temperature is 100 to 300 ℃, preferably 150 to 200 ℃, and the pressure is 0.2 to 1.5MPa, preferably 0.6 to 1.0MPa.
In the adsorption separation unit, the adsorption separation tower adopts a fixed bed, and the positions of a material inlet and a material outlet of the fixed bed adsorption equipment are changed to generate the effect that the adsorbent continuously moves downwards and the material continuously moves upwards. The bed is filled with an adsorbent with high selectivity to p-xylene. The active component of the adsorbent is X-type zeolite or Y-type molecular sieve of Ba or BaK, and the binder is selected from kaolin, silicon dioxide or alumina. The desorbent is mutually soluble with each component in the raw material and is also mutually soluble with C 8 The boiling points of the components in the aromatic hydrocarbon have larger difference, and the components are easy to recycle, preferably p-diethylbenzene or toluene.
The operation conditions of the extract fractionating tower are as follows: the pressure at the top of the column is 0.1 to 0.5MPa, the operation is preferably normal pressure, and the temperature at the top of the column is 50 to 200 ℃, preferably 100 to 150 ℃.
The operation conditions of the raffinate tower are as follows: the pressure at the top of the tower is 0.1-1.0 MPa, the operation at normal pressure is preferred, and the temperature at the top of the tower is 120-170 ℃.
The isomerization unit operation conditions are as follows: the reaction temperature is 300-450 ℃, preferably 330-400 ℃, the pressure is 0.1-2.0 MPa, preferably 0.4-1.5 MPa, and the mass space velocity is 2-10 h -1 Preferably 3 to 6 hours -1 The molar ratio of hydrogen reacted to hydrocarbon is from 2 to 8, preferably from 3 to 6. The reboiling heat of the isomerization product fractionating tower is provided by heating the convection section of the isomerization reaction heating furnace, and the deficiency is provided by the reboiling furnace.
In the isomerization unit, an isomerization catalyst is filled in an isomerization reactor, and the isomerization catalyst is an active component of one or more of Pt, sn, mg, bi, pb, pd, re, mo, W, V and rare earth metals loaded on a molecular sieve and/or an inorganic oxide carrier. The molecular sieve is one or a mixture of more of five-membered ring molecular sieve, mordenite, EUO type molecular sieve and MFI molecular sieve. The inorganic oxide is alumina and/or silica.
The operation conditions of the isomerization product fractionating tower are as follows: the pressure at the top of the tower is 0.2-2.0 MPa, preferably 0.5-1.5 MPa, and the temperature at the top of the tower is 50-250 ℃, preferably 130-170 ℃.
Compared with the prior art, the invention has the following advantages:
(1) The extraction liquid fractionating tower with a dividing wall tower structure is arranged in the adsorption separation unit, and an extraction liquid tower and a finished product tower in the conventional process are omitted, so that the back mixing degree of p-xylene in the separated components is reduced, the thermodynamic efficiency of separation is improved, and meanwhile, the phenomenon that the extraction liquid tower cools the toluene and the p-xylene components in the conventional process, and the heat entering the finished product tower for separation is unreasonably utilized after being heated is avoided; in the conventional process, reboiling loads of an extract tower and a finished product tower are respectively provided by materials at the top and the bottom of a dimethylbenzene tower and a desorbent, the extract fractionating tower with a dividing wall tower structure is arranged, the reboiling loads can be completely provided by the materials at the top of the dimethylbenzene tower, the heat of the materials at the top of the dimethylbenzene tower is fully recovered, and the use of the heat of the materials at the bottom of the dimethylbenzene tower is reduced, so that the fuel gas consumption of a reboiling furnace of the dimethylbenzene tower is saved, meanwhile, the top of the extract fractionating tower only needs to cool methylbenzene and part of p-dimethylbenzene components, and the condensation load is reduced; desorbent materials at the bottoms of the extract fractionating tower and the raffinate tower are not used as heat sources of a reboiler of a finished product tower, but used for preheating isomerization reaction feeding, so that the temperature of the reaction feeding into an isomerization heating furnace is increased, and the fuel gas consumption of the isomerization heating furnace is reduced;
(2) By arranging the isomerization fractionating tower with a dividing wall tower structure, a deheptanizer in the conventional process is omitted, the isomerization reaction product is skillfully pre-separated by the isomerization fractionating tower, and the tower bottom C in the isomerization reaction product 9 + Aromatics and overhead C 7 The lower light hydrocarbon is separated out from the device in advance, and the side stream material is C 8 Aromatic hydrocarbons are directly mixed with the adsorptive separation feed, whereas in the conventional process, the C is not treated in the deheptanizer 9 + The aromatic hydrocarbon is separated, so that the operation load of the clay tower is increased, and meanwhile, the material passing through the clay tower needs to enter the xylene tower again, so that the operation load of xylene is greatly increased; compared with the conventional process, the isomerization reaction product is cooled by an air cooler and a water cooler, gas-phase components such as hydrogen and the like are separated by a gas-liquid separation tank, the liquid-phase components are reheated, and C is separated by a deheptanizer 7 - Light component, C 8 + Returning the components to the xylene tower for further separation to obtain C 8 The cooling load is large in the process, and after gas-phase components such as hydrogen are separated, the liquid-phase components are reheated. The invention solves the problem of unreasonable energy utilization of the conventional process of cooling before heating, and greatly reduces the cooling load. In the conventional process flow, the temperature of an isomerization reaction feed of an isomerization reaction unit in an isomerization reaction heating furnace is about 280 to 300 ℃; the isomerization reaction unit of the invention cancels the deheptanizer, and simultaneously, through optimizing a heat exchange network, the isomerization reaction feeding material does not undergo the process of cooling first and then heating, namely, the heat of the isomerization reaction feeding material (the side line material at the upper part of the raffinate tower) is prevented from heating the cooled deheptanizer feeding material, the cold and hot material flows are reasonably matched, and the temperature of the isomerization reaction feeding material in front of the furnace is increased to 310 to 330 ℃, so that the consumption of fuel gas of the isomerization reaction heating furnace is reduced, the energy consumption is greatly reduced, and the economic benefit and the social benefit are improved.
Drawings
Fig. 1, 2 and 3 are schematic flow diagrams of a xylene fractionation unit, an adsorption separation unit and an isomerization unit of a xylene plant according to the present invention, respectively.
Wherein, fig. 1 is a xylene fractionation unit, which comprises a xylene column 101, a heat exchanger I102 and a xylene reboiling furnace 103; FIG. 2 is an adsorptive separation unit comprising an adsorptive separation column 201, an extract fractionation column 202, a raffinate column 203, and a heat exchanger II204; fig. 3 is an isomerization reaction unit, which includes an isomerization reactor 301, an isomerization product fractionation column 302, a clay column 303, an isomerization reaction heating furnace 304, a compressor 305, a heat exchanger III306, a heat exchanger IV307, and a heat exchanger V308.
Fig. 4, 5 and 6 are schematic flow diagrams of a xylene fractionation unit, an adsorption separation unit and an isomerization reaction unit, respectively, of a conventional xylene plant.
Wherein, fig. 4 is a xylene fractionation unit, which comprises a xylene column 401, a heat exchanger I402 and a xylene reboiling furnace 403; FIG. 5 shows an adsorption separation unit comprising an adsorption separation column 501, an extract column 502, a raffinate column 503, a finished product column 504, a finished product reboiler I505, and a finished product reboiler II506; fig. 6 is an isomerization reaction unit, which includes an isomerization reactor 601, a deheptanizer 602, a clay column 603, a gas-liquid separation tank 604, an isomerization reaction heating furnace 605, a heat exchanger III606, a heat exchanger IV607, a heat exchanger V608, a heat exchanger VI609, a compressor 610, an air cooler 611, and a water cooler 612.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
Detailed Description
The paraxylene production process of the present invention will be described in more detail below with reference to the accompanying drawings.
The xylene fractionation unit comprises 8 The aromatic hydrocarbon mixture raw material 104 is fed to a feed line 107 of the xylene column; line 108 feeding the overhead discharge to heat exchanger I102; a pipeline 109 for circulating a part of the discharged material at the top of the tower after the heat exchange of the heat exchanger I102 back to the xylene tower; the other part of the overhead discharge 105 after heat exchange by the heat exchanger I102 is sent to a pipeline 110 of a heat exchanger III 306; a feed line 112 for feeding a portion of the bottoms 111 to the bottom reboiling furnace 103; a line 113 for recycling the bottom material heated by the bottom reboiler 103 to the xylene column; will be additionally providedA line 114 for withdrawing a portion of the bottoms 106 from the xylene column; wherein the overhead output 105 is C 8 Aromatic hydrocarbons, bottoms 106 being C 9 + An aromatic hydrocarbon;
the adsorption separation unit comprises a pipeline 209 for feeding the overhead discharge 205 of the xylene fractionation unit after heat exchange to an adsorption separation tower, a pipeline 210 for sending the extract rich in p-xylene separated by the adsorption separation tower 201 to the extract fractionation tower 202, and a pipeline 214 for sending the raffinate poor in p-xylene obtained by adsorption separation by the adsorption separation tower 201 to the raffinate column 203; a line 211 for withdrawing overhead 206 from the extract fractionator 202, and a line 212 for withdrawing side 207 from the extract fractionator 202; the material at the bottom of the extract fractionating tower 202 is sent to a pipeline 213 of a heat exchanger II204, the material at the bottom of the raffinate tower (desorbent) is sent to a pipeline 217 of the heat exchanger II204, and the material at the bottom of the extract fractionating tower 202 and the material at the bottom of the raffinate tower after heat exchange are sent to a pipeline 218 of the adsorption separation tower 201; the upper side draw 215 of the raffinate column 203 is heat exchanged in exchanger II204 and fed 208 to line 216 of the isomerization unit.
The isomerization reaction unit comprises a feed line 316 for feeding isomerization reaction feed 208 to the isomerization reactor 301, wherein the feed line 216 is connected with a heat exchanger III306, a heat exchanger IV307 and an isomerization reaction heating furnace 305 in sequence through lines 312, 315 and 316 before being connected with the isomerization reactor 301; hydrogen 309 from feed line 313 to compressor 304, compressor outlet line 314 connected to feed line 312 of isomerization reactor 301, mixed with isomerization feed 208; a feed line 318 for feeding the isomerized reaction product to the isomerized product fractionation column 302, the feed line 318 being connected to the isomerized reactor outlet line 317 via a heat exchanger IV307 prior to connection to the isomerized product fractionation column 302; an outlet line 319 for the overhead 310 from the isomerate fractionation column 302; a feeding line 321 for feeding the side line material of the isomerization product fractionating tower 302 to the clay tower 303, wherein the feeding line 320 is connected with the front part of the clay tower 303 and is connected with a heat exchanger V308; a discharge pipeline 322 at the bottom of the clay tower 303 is connected with a heat exchanger V308, and a pipeline 323 after heat exchange is connected with the adsorption separation feed pipeline 110; an effluent line 324 that discharges the isomerate fractionation column 302 bottoms 311.
The process flow of the device for producing the paraxylene comprises the following steps: containing C 8 The aromatic hydrocarbon mixture raw material 104 enters a xylene column 101 for fractionation, after heat exchange is carried out on the overhead material flowing through a heat exchanger I102, one part of the overhead material returns to the xylene column 101 as reflux, and the other part of the overhead material is used as an adsorption separation feed 105, and after heat exchange is carried out on the overhead material and an isomerization reaction feed through a heat exchanger III306, the overhead material is sent to an adsorption separation column 201; the bottom material of the tower returns to the xylene tower 101 after passing through the xylene reboiling furnace 103 and the temperature is raised, and the other part of the bottom material 106 is C 9 + An aromatic hydrocarbon.
The adsorption separation feed 205 is subjected to adsorption separation by an adsorption separation tower 201, the obtained paraxylene-rich extract enters an extract fractionating tower 202 for fractionation, a tower bottom material is a desorbent, and after being mixed with a tower bottom material of a raffinate tower 203, the desorbent exchanges heat with the isomerization reaction feed by a heat exchanger II204 and returns to the adsorption separation tower 201; the material at the top of the extract fractionating tower 202 is toluene 206; the side stream material is p-xylene 207; the p-xylene depleted raffinate obtained by adsorption separation in the adsorption separation tower 201 enters a raffinate tower 203 for fractionation, and the upper side line material passes through a heat exchanger II204, a heat exchanger III306 and a heat exchanger IV307 in sequence to exchange heat with a desorbent, an adsorption separation feed and an isomerization reaction product respectively; after the pressure of the hydrogen 309 is increased by the compressor 304, the hydrogen and the isomerization reaction material 208 are mixed and enter a heat exchanger IV307; then the mixed material is heated by an isomerization heating furnace 305 and enters an isomerization reactor 301 for isomerization reaction, and a reaction product enters an isomerization product fractionating tower 302 after heat exchange by a heat exchanger IV307; the top material of the isomerization product fractionating tower 302 is C 7 The following light hydrocarbons and hydrogen 310; the side stream material of the isomerization product fractionating tower 302 exchanges heat through a heat exchanger V308, enters a clay tower 303 to remove unsaturated hydrocarbons such as olefin and the like, and the tower bottom material exchanges heat with the feeding material of the clay tower 303 and then is mixed with the adsorption separation feeding material 105; the bottoms 311 of the isomerate fractionation column 302 is C 9 + An aromatic hydrocarbon.
The process flow of the conventional xylene plant is as follows: containing C 8 The aromatic hydrocarbon mixture raw material 404 enters a xylene column 401 for fractionation, after heat exchange is carried out on a tower top material flowing through a heat exchanger I402, one part of the tower top material returns to the xylene column 401 as reflux, and the other part of the tower top material returns to the xylene column 401 as refluxAs an adsorption separation feed 405, the feed is sent to the adsorption separation tower 501 after being subjected to heat exchange with the feed of the deheptanizer 602 through a heat exchanger VI 609; the bottom material of the tower returns to the xylene tower 401 after passing through the xylene reboiling furnace 403 and the temperature is raised, and the other part of the bottom material 406 is C 9 + An aromatic hydrocarbon. The tower top material flow is mainly used as a heat source of a reboiler of the raffinate tower 503 and a reboiler of the extract tower 502; the bottoms stream serves primarily as the heat source for the finishing column reboiler 506 and the deheptanizer 602 reboilers.
The adsorption separation feeding 507 is subjected to adsorption separation by an adsorption separation tower 501, the obtained p-xylene-rich extract enters an extract tower 502 for fractionation, the tower bottom material is a desorbent, and is mixed with the tower bottom material of a raffinate tower 503 to be used as a heat source of a finished product tower reboiler 505 and then returns to the adsorption separation tower 501; the material at the top of the extract tower 502 enters a finished product tower 504, the material at the bottom of the finished product tower is p-xylene 509, and the toluene 508 is at the top of the tower. The p-xylene depleted raffinate obtained by adsorption separation in the adsorption separation tower enters a raffinate tower 503, the material on the upper side line passes through a heat exchanger III606 and a heat exchanger IV607 in sequence, exchanges heat with the deheptanizer feed and the isomerization reaction product respectively, then enters an isomerization reactor 601 for isomerization reaction after being heated by an isomerization reaction heating furnace 605, and the reaction product enters a gas-liquid separation tank 604 after exchanging heat by the heat exchanger IV607, is cooled by an air cooler 611 and a water cooler 612, and is separated into a gas-liquid two phase;
the gas phase is discharged from the top of the gas-liquid separation tank 604 and divided into two streams: one stream of the externally discharged hydrogen 613 is sent to a TSA unit (temperature swing adsorption unit) or a hydrogenation plant, and can also be sent to a fuel gas system; the other stream is mixed with hydrogen 614, pressurized by a compressor 610 and mixed with the isomerization feed; the liquid phase material obtained by separation in the gas-liquid separation tank 604 enters the deheptanizer 602 after heat exchange in the heat exchanger III606, the heat exchanger V608 and the heat exchanger VI 609. The material at the top of the deheptanizer 602 is C 7 The bottom material of the light hydrocarbon 615 is returned to the xylene column 401 after passing through a heat exchanger V608 and unsaturated hydrocarbons such as olefin are removed by a clay column 603.
The effect of the novel p-xylene production process provided by the present invention is specifically illustrated by the following examples.
Comparative example 1
Comparative example 1 illustrates the process and energy consumption of a conventional para-xylene production process. The equipment used is shown in Table 1, and the plant operating parameters and energy consumption are shown in Table 2.
Example 1
Example 1 illustrates the process and energy consumption of the novel para-xylene production process provided by the present invention. The equipment used is shown in Table 1, and the plant operating parameters and energy consumption are shown in Table 2.
TABLE 1
TABLE 2
As can be seen from tables 1 and 2, the process for producing paraxylene according to the present invention can save the equipment investment, and reduce the investment for 1 set of rectification column, cooler reboiler equipment, and 1 knock-out drum, air cooler, and water cooler, respectively, as compared with comparative example 1. The method provided by the invention not only reduces the number of equipment, but also reduces the energy consumption by 19.2%. Therefore, the novel method for producing the paraxylene provided by the invention can reduce equipment investment and floor area, reduce the operation load of the xylene tower and save the fuel gas consumption of the xylene reboiling furnace. Meanwhile, a heat exchange network is optimized, the temperature of the isomerization reaction feeding furnace is increased, the consumption of fuel gas of the isomerization reaction heating furnace is reduced, and the cooling loads of water cooling and air cooling after the isomerization reaction product is obtained, so that the problem that the material is cooled first and then heated is avoided, the energy consumption is greatly reduced, and the economic benefit and the social benefit are improved.
Claims (19)
1. The device for producing p-xylene is characterized in that: comprises a xylene fractionation unit, an adsorption separation unit and an isomerization reaction unit; the xylene fractionation unit comprises a xylene tower, a heat exchanger I and a xylene reboiling furnace; the adsorption separation unit comprises an adsorption separation tower, an extract liquid fractionating tower, a raffinate tower and a heat exchanger II; the isomerization reaction unit comprises an isomerization reactor, an isomerization product fractionating tower, a clay tower, an isomerization reaction heating furnace, a heat exchanger III, a heat exchanger IV, a heat exchanger V and a compressor;
the xylene fractionation unit further comprises a unit for fractionating C 8 The aromatic hydrocarbon mixture raw material is fed into a feed pipeline of the xylene tower; a line for sending the overhead discharge to a heat exchanger I; circulating a part of the discharged material at the top of the tower after heat exchange by the heat exchanger I back to a pipeline of the xylene tower; the other part of the discharged material at the top of the tower after the heat exchange of the heat exchanger I is sent to a pipeline of the adsorption separation unit; a feed line for feeding a portion of the bottoms to a bottom reboiling furnace; a line for recycling the bottom material heated by the bottom reboiling furnace to the xylene column; the other part of the tower bottom material is discharged out of a pipeline of the xylene tower; wherein the top discharge of the tower is C 8 Aromatic hydrocarbon, the material at the bottom of the tower is C 9 + An aromatic hydrocarbon;
the adsorption separation unit also comprises a pipeline for feeding the tower top discharge of the xylene fractionation unit after heat exchange to an adsorption separation feeding pipeline of an adsorption separation tower, delivering the separated p-xylene-rich extract to an extract fractionation tower, and delivering the p-xylene-poor raffinate obtained by adsorption separation of the adsorption separation tower to a raffinate tower; a pipeline for discharging the materials at the top of the extract fractionating tower and a pipeline for discharging the materials at the side line of the extract fractionating tower; the method comprises the following steps of (1) sending an extract fractionating tower bottom material to a pipeline of a heat exchanger II, sending a raffinate tower bottom material desorbent to a pipeline of the heat exchanger II, and sending the extract fractionating tower bottom material and the raffinate tower bottom material subjected to heat exchange to a pipeline of an adsorption separation tower; feeding the side line discharge at the upper part of the raffinate tower into a pipeline of an isomerization reaction unit after heat exchange of a heat exchanger II;
the isomerization reaction unit also comprises a feed pipeline for feeding the isomerization reaction to the isomerization reactor, and the feed pipeline is sequentially connected with a heat exchanger III, a heat exchanger IV and an isomerization reaction heating furnace before being connected with the isomerization reactor; a feed line for feeding the isomerized product to the isomerized product fractionation column, the feed line being connected to the heat exchanger IV before being connected to the isomerized product fractionation column; isomerizingProduct fractionating column overhead material C 7 A discharge line for discharging the light hydrocarbon and hydrogen; feeding the side-line material of the isomerization product fractionating tower into a feeding pipeline of the clay tower, wherein the feeding pipeline is connected with a heat exchanger V in front of the clay tower; a discharge pipeline for discharging the product at the bottom of the clay tower, wherein the discharge pipeline is sequentially connected with a heat exchanger V and an adsorption separation feeding pipeline; a discharge line for discharging the isomerized product fractionation column bottoms; hydrogen enters a compressor through a feeding pipeline to be boosted, and an outlet pipeline of the compressor is merged into a feeding pipeline of an isomerization reaction rectification fractionating tower; the extract fractionating tower and the isomerized product fractionating tower adopt a dividing wall tower form; the heat exchanger III is used for exchanging heat between the feeding material of the adsorption separation tower and the feeding material of the isomerization reaction, improving the temperature of the feeding material of the isomerization reaction and reducing the temperature of the feeding material of the adsorption separation tower to a proper temperature.
2. The apparatus of claim 1, wherein: the xylene column is used for separating C 8 Component (A) and (C) 9 + The component is a plate-type rectifying tower.
3. The apparatus of claim 1, wherein: the heat exchanger I is used for taking the xylene overhead material flow as a heat source of a reboiler of a raffinate tower and a reboiler of a draw liquid fractionating tower, one part of condensed liquid after heat exchange is taken as reflux and returned to the xylene tower, and the other part of condensed liquid is taken as adsorption separation feeding.
4. The apparatus of claim 1, wherein: the xylene reboiling furnace is used for heating materials which are recycled to the bottom of the tower, and provides reboiling heat for the xylene tower.
5. The apparatus of claim 1, wherein: the adsorption separation tower is used for separating paraxylene and isomers thereof in materials from a xylene fractionation unit.
6. The apparatus of claim 1, wherein: the extract fractionating tower is used for separating toluene, paraxylene and desorbent in the paraxylene-rich extract to obtain a high-purity paraxylene product; the material at the bottom of the extract fractionating tower is a desorbent, the material at the top of the tower is toluene, and the material at the side line is a paraxylene product.
7. The apparatus of claim 1, wherein: the raffinate tower is used for separating C in the p-xylene-poor raffinate 8 The components and the desorbent are discharged from the upper side line of the raffinate tower as the lean p-xylene C 8 The components, the discharge from the bottom of the tower is the desorbent.
8. The apparatus of claim 1, wherein: the heat exchanger II is used for exchanging heat between a desorbent and an isomerization feed, improving the temperature of the isomerization feed and reducing the load of an isomerization reaction heating furnace; and simultaneously reducing the temperature of the desorbent to the proper temperature of the desorbent returning to the adsorption separation tower.
9. The apparatus of claim 1, wherein: the isomerization reactor is used for separating the lean p-xylene C from the adsorption separation unit 8 Conversion of the component into para-xylene-rich C 8 And (4) components.
10. The apparatus of claim 1, wherein: the isomerization product fractionating tower is used for separating the isomerization reactor discharge rich in the paraxylene C 8 C in component (A) 7 Lower light hydrocarbon, C 8 Aromatic hydrocarbon and C 9 + An aromatic hydrocarbon component.
11. The apparatus of claim 1, wherein: the heat exchanger IV is used for heat exchange between the isomerization feed and the isomerization reaction product.
12. The apparatus of claim 1, wherein: the heat exchanger V is used for exchanging heat between the side line material of the isomerization product fractionating tower as the feeding material of the clay tower and the discharging material of the clay tower, and improving the discharging temperature of the clay tower; and mixing the clay tower discharge after heat exchange with the material after heat exchange on the top of the xylene tower, and taking the mixture as the feed of the adsorption separation tower to further separate out the paraxylene.
13. A process for producing paraxylene, characterized by comprising the following steps: containing C 8 The aromatic hydrocarbon mixture raw material enters a xylene tower for fractionation, after heat exchange is carried out on the tower top material by a heat exchanger I, one part of the tower top material is returned to the xylene tower as reflux, the other part of the tower top material is used as adsorption separation feeding material, and after heat exchange is carried out on the tower top material and isomerization reaction feeding material by a heat exchanger III, the tower top material is sent to an adsorption separation tower; the bottom material of the tower returns to the xylene tower after passing through the xylene reboiling furnace and being heated, and the other part of the bottom material of the tower is C 9 + Aromatic hydrocarbons; the adsorption separation feeding is subjected to adsorption separation by an adsorption separation tower, the obtained p-xylene-rich extract enters an extract fractionating tower for fractionation, the tower bottom material is a desorbent, and after being mixed with the raffinate tower bottom material, the desorbent exchanges heat with the isomerization reaction feeding by a heat exchanger II and returns to the adsorption separation tower; toluene is taken as a material at the top of the extract fractionating tower, and paraxylene is taken as a material at the side line; the p-xylene depleted raffinate obtained by the adsorption separation in the adsorption separation tower enters a raffinate tower for fractionation, the upper side line material sequentially flows through a heat exchanger II, a heat exchanger III and a heat exchanger IV to exchange heat with a desorbent, an adsorption separation feed and an isomerization reaction product respectively, then the mixture enters an isomerization reactor for isomerization reaction after being heated by an isomerization reaction heating furnace, and the reaction product enters an isomerization product fractionating tower after being subjected to heat exchange in the heat exchanger IV; the material at the top of the isomerization product fractionating tower is C 7 The following light hydrocarbons and hydrogen; the side line material of the isomerization product fractionating tower exchanges heat through a heat exchanger V, enters a clay tower to remove unsaturated hydrocarbon, exchanges heat with the feed of the clay tower to be used as adsorption separation feed, and the bottom discharge of the isomerization product fractionating tower is C 9 + Aromatic hydrocarbons; the extract fractionating tower and the isomerized product fractionating tower are in the form of dividing wall towers.
14. The process of claim 13, wherein: the top pressure of the xylene column is 0.3 to 2.5 MPa, and the temperature at the top of the xylene column is 50 to 300 ℃.
15. The process of claim 13, wherein: the operating conditions of the adsorption separation unit are as follows: the temperature is 100-300 ℃, and the pressure is 0.2-1.5 MPa.
16. The process of claim 13, wherein: the operation conditions of the extract fractionating tower are as follows: the pressure at the top of the tower is 0.1-0.5 MPa, and the temperature at the top of the tower is 50-200 ℃.
17. The process of claim 13, wherein: the operation conditions of the raffinate tower are as follows: the pressure at the top of the tower is 0.1-1.0 MPa, and the temperature at the top of the tower is 50-300 ℃.
18. The process of claim 13, wherein: the isomerization unit operation conditions are as follows: the reaction temperature is 300-450 ℃, the pressure is 0.1-2.0 MPa, the mass space velocity is 2-10 h- 1 The reaction hydrogen/hydrocarbon molar ratio is 2 to 8.
19. The process of claim 13, wherein: the operation conditions of the isomerization product fractionating tower are as follows: the pressure at the top of the tower is 0.2-2.0 MPa, and the temperature at the top of the tower is 50-250 ℃.
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Effective date of registration: 20231101 Address after: 100728 No. 22 North Main Street, Chaoyang District, Beijing, Chaoyangmen Patentee after: CHINA PETROLEUM & CHEMICAL Corp. Patentee after: Sinopec (Dalian) Petrochemical Research Institute Co.,Ltd. Address before: 100728 No. 22 North Main Street, Chaoyang District, Beijing, Chaoyangmen Patentee before: CHINA PETROLEUM & CHEMICAL Corp. Patentee before: DALIAN RESEARCH INSTITUTE OF PETROLEUM AND PETROCHEMICALS, SINOPEC Corp. |