CN111777481B

CN111777481B - Novel process for producing triphenyl by utilizing aromatization of cracking carbon penta

Info

Publication number: CN111777481B
Application number: CN202010689416.4A
Authority: CN
Inventors: 王岩; 蔡明月; 王意平; 彭艺; 杨蕊; 朱泓宇
Original assignee: Qingdao University
Current assignee: Qingdao University
Priority date: 2020-07-17
Filing date: 2020-07-17
Publication date: 2023-04-11
Anticipated expiration: 2040-07-17
Also published as: CN111777481A

Abstract

The invention discloses a novel process for producing triphenyl by aromatization of a byproduct carbon five fraction of an ethylene cracking device, which adopts a catalytic hydrogenation method to crack an ethylene byproduct cracking carbon five fraction into pentane, then couples n-pentane and methanol for aromatization, and adopts an acidic molecular sieve catalyst to obtain three high-added-value products of high-purity benzene, toluene and xylene through a series of processes of reaction, absorption, stabilization and separation. The process can directly prepare high-purity triphenyl from the cracked ethylene byproduct, namely the cracked C5, so that the cracked C five fraction can be used as a fuel and a product with a high added value, and the process has good economic and social benefits and market popularization prospects.

Description

Novel process for producing triphenyl by utilizing aromatization of cracking carbon penta

Technical Field

The invention belongs to the field of organic chemical raw material production, and particularly relates to a novel process for producing triphenyl by aromatization of a byproduct carbon five fraction (cracking carbon five for short) of an ethylene cracking device.

Background

In recent years, the technology of refining and chemical integration in China and the technology of preparing olefin from coal (methanol) are rapidly developed, the ethylene capacity is continuously expanded, and the five-fraction cracked carbon generated in the production process is rapidly increased, so that the five-fraction cracked carbon becomes a non-negligible associated resource in the ethylene industry. The method utilizes different components in the carbon five fraction to produce refined, diversified and high-end chemical products, develops the application field of the products, realizes high-value comprehensive utilization of the carbon five resource (especially the carbon five alkane resource), and is an important way for improving the core competitiveness of the ethylene industry. Meanwhile, china vigorously promotes and develops clean energy automobiles, the increment of the fuel oil requirement for the automobiles is greatly reduced, and the energy utilization approach of carbon pentaalkane resources tends to shrink. The effective utilization of a considerable amount of carbon five resources to produce downstream products with both use value and market demand is a challenging task faced by the chemical engineering and technology industry. In conclusion, the method has important practical significance for high-value utilization research of the cracked carbon five resources.

Cracking C five, which means the by-product C five fraction of the ethylene cracking device, mainly contains C five alkanes, alkenes, alkadienes, C four, etc. The cracked C5 can be directly used as fuel or used as an oil blending component of gasoline after hydrogenation stabilization treatment, and in recent years, as the domestic liquefied gas market has larger gaps, a plurality of research institutions carry out substitution tests in the aspect, namely, the most easily polymerized cyclopentadiene in the C5 is removed, and then proper antioxidant, polymerization inhibitor and solvent are added, and the treated C five can be used as civil liquefied gas fuel. However, as an internationally recognized raw material resource, the utilization of carbon five as a fuel is a great waste. In this regard, the related scholars have conducted research on resource utilization of cracked carbon five, for example, guo Yanfeng, etc. conducted research on feasibility of using cracked carbon five raffinate hydrogenated product blended with light naphtha as ethylene feedstock, comparing yield and value of cracked product and examining results of coking performance thereof, and it was proved that it is feasible to use cracked carbon five raffinate blended with light naphtha as ethylene feedstock (Guo Yanfeng, wang Peng, peng Guanghui, wang Wenbin, yuanhua, zhang Jian. Research on using cracked carbon five raffinate as ethylene feedstock, zlu petrochemical, 2016, 44 (1): 1-4); li Meiying summarizes the current situation of the utilization of cracked carbon five resources in our country, and proposes that the carbon five components in our country are mainly concentrated on the diolefin components such as isoprene, dicyclopentadiene and piperylene, wherein isoprene is the highest, and is the carbon five component with the highest utilization rate and added value in our country so far, and the large-scale production of downstream products such as butyl rubber, SIS and isoprene rubber has been realized in the utilization of isoprene resources (Li Meiying. Current situation of the utilization and analysis of cracked carbon five resources in our country. Current petrochemical, 11 th stage 2012).

The aromatic industry plays an important role in the Chinese economy, and its refining coal chemical industry forms a large refining system juxtaposed to the olefin industry. But the current domestic aromatic hydrocarbon industry faces the problems of serious shortage of productivity and high external dependence. Benzene, toluene and xylene (BTX, referred to as triphenyl for short) which are representative substances in aromatic hydrocarbons are important petrochemical basic raw materials, and have wide application in the fields of medicine, national defense, building material coating, textile and the like, and the BTX in China is short of supply and demand for a long time and conflicts in supply and demand. The low-carbon hydrocarbon aromatization technology is an industrial technology for converting low-carbon hydrocarbons into aromatic hydrocarbons through aromatization reaction, can convert low-carbon hydrocarbons (such as carbon five fraction) with low price into BTX with high added value, solves the problems of excess capacity of the carbon five fraction and shortage of supply of the aromatic hydrocarbons, and has wide development prospect. However, the price of BTX is low at present, the prices of benzene, toluene and xylene are about 6000 yuan/ton, and the investment recovery period of the project is long and even the project is deficient. Traditionally, most BTX production is based on catalytic reformate and pyrolysis gasoline. However, the low crude oil reserves in china, which leads to a huge gap between the supply and demand of aromatics, import remains one of the indispensable sources. In 2017, the inlet decline tendency of benzene and o-xylene was 23% and 30%, respectively. This forces china to find alternative ways to address the problem of imbalanced supply and demand for aromatics. For example, the research and development of the carbon tetrad aromatization technology for producing mixed aromatics by the research and development of the petroleum lanzhou chemical research center in China, and the industrial application of the device for producing the mixed aromatics by aromatizing the carbon tetrad at 200kt/a by Henan Puyang Hengyan petrochemical company, under the optimal reaction conditions, the carbon tetrad conversion rate is 99.02%, the mass fraction of the aromatics in a liquid phase product is 56.48%, wherein the mass fraction of benzene is 2.01%, the mass fraction of toluene is 11.58%, and the mass fraction of xylene is 19.00% (Li Jichun, jing Li, wang Xiaojiang, wang Mei. The research and development of the carbon tetrad aromatization technology for producing the mixed aromatics and the industrial application, petroleum refining and chemical industry, 2019, 5 th volume in 5 months and 50 months); the Zhang Guangdong and the like investigate the feasibility of aromatizing n-pentane to produce propane and aromatic hydrocarbon and discuss the reaction path and the process conditions of aromatizing n-pentane to produce propane and aromatic hydrocarbon, under the optimal process conditions, the conversion rate of n-pentane is 98.44%, the yield of propane is 53.02%, and the yield of aromatic hydrocarbon is 11.25% (Zhang Guangdong, zhongwei, wang Zijian, ma Aizeng. The reaction path and the process conditions of aromatizing n-pentane to produce propane. The petrochemical report of 2020, vol.36, no. 2 of 3/36); zhang et al studied the technology of aromatic hydrocarbon production by co-aromatization of n-pentane with methanol and compared with the aromatization reaction with methanol alone, and the results showed that the co-aromatization reaction had slower catalyst deactivation compared with the aromatization reaction with methanol alone, and the co-aromatization reaction could obtain higher aromatic hydrocarbon selectivity compared with the aromatization reaction with n-pentane alone (Aromatics production from methanol and pentanes: commercial process design, synthetic energy and technology-environmental analysis, computers and Chemical Engineering,2019, 126.

However, the technology for producing high-purity triphenyl by directly cracking the carbon-acanthopanax hydrogen by using the ethylene cracking byproduct to obtain saturated alkane and then coupling the saturated alkane with methanol for aromatization has not been reported so far.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and design and provide a novel process for producing triphenyl by utilizing aromatization of the cracking carbon penta, which has simple process and low cost.

In order to realize the aim, the invention relates to a novel process for producing triphenyl by utilizing aromatization of cracking carbon penta, which comprises the following steps:

(1) Process for cracking carbon acanthopanax hydrogen

The cracking carbon five mainly comprises pentane pentene and a very small amount of four carbon components, the cracking carbon five fed by a feed pump 1 is mixed with hydrogen by a mixer 1, the mixture enters a first-stage hydrogenation reactor, the reactor is a fixed bed adiabatic reactor, the inlet temperature of the first-stage reactor is 36-40 ℃, the inlet pressure is 2.8-3.3 MPa, unsaturated diolefin is subjected to first-stage hydrogenation by the first-stage hydrogenation reactor to generate carbon pentamonoolefin, the outlet temperature of the first-stage reactor is 80-100 ℃, and the outlet pressure is 2.9-3.2 MPa. Then the mono-olefin is heated by a heat exchanger 1 and a water cooler 1 respectively and then enters a second-stage hydrogenation reactor, the reactor type is a fixed bed adiabatic reactor, the inlet temperature of the second-stage reactor is 140-165 ℃, the inlet pressure is 2.9-3.2 MPa, the mono-olefin generates carbon pentaalkane after the second-stage hydrogenation, the outlet temperature of the second-stage reactor is 280-300 ℃, and the outlet pressure is 2.8-3.0 MPa. The carbon pentaalkane from the second-stage hydrogenation reactor is cooled by a heat exchanger 1 and a water cooler 2, enters a high-pressure separator to separate most of unreacted hydrogen and trace carbon tetraalkane, is compressed by a compressor 1 and exchanges heat with the heat exchanger 2, then enters a mixer 1 to circulate, enters a low-pressure separator to separate a small part of residual hydrogen, and then enters an isopentane separation tower. The carbon pentaalkane is separated by an isopentane separation tower, isopentane with the purity of 95 percent obtained at the tower top can be used as a raw material of a foaming agent, n-pentane with the purity of 98 percent is obtained at the tower bottom, and the n-pentane enters an aromatization reaction section after being cooled by a water cooler 3. The specific process is shown in figure 1.

(2) N-pentane-methanol coupling aromatization reaction process

(1) The aromatization reaction process of the n-pentane methanol comprises the following steps: n-pentane obtained from a hydrogenation section enters a feeding tank 1, then enters a mixer 2 through a pump 2, meanwhile, methanol entering from the feeding tank 2 is sent into the mixer 2 through a pump 3, two feeds are mixed and then enter a heat exchanger 3 for preheating, then enter aromatization reactors A and B for reaction after being heated through a heating furnace, the reactors A and B are both fixed bed adiabatic reactors, ZSM-5 acidic molecular sieve catalysts are respectively filled in the reactors, the inlet temperature of the reactors is 540-570 ℃, and the inlet pressure is 0.25-0.31 MPa. The aromatization reaction of the methanol is an exothermic reaction, water is generated in the reaction process, and the catalyst is easily deactivated under the action of high temperature and steam, so that the yield of the aromatic hydrocarbon is reduced. The aromatization reaction of the n-pentane is an endothermic reaction, the reaction temperature is generally above 500 ℃, a heating furnace is required to supplement more heat, and the reaction has higher energy consumption. The design flow couples the aromatization reaction of the n-pentane with the aromatization reaction of the methanol, can effectively perform heat complementation, is beneficial to controlling the temperature of equipment, reduces the production cost, and can obviously improve the yield of the target product benzene by introducing the methanol. After methanol and n-pentane react in the aromatization reactors A and B, the outlet temperature is 430-460 ℃, and the outlet pressure is 0.27-0.32 MPa. After being respectively cooled by the heat exchanger 3, the air cooler 1 and the water cooler 4, the gas-liquid mixture enters an absorption stabilization section, and the specific flow is shown in figure 2.

(2) The absorption stabilizing process of the aromatization device comprises the following steps: the aromatization product is separated into dry gas, liquefied gas and high-octane number stable gasoline (rich in benzene, toluene and mixed xylene) by absorption and rectification. The absorption stabilizing system consists of an absorption tower, a desorption tower and a stabilizing tower, a reaction product is cooled to 30-50 ℃ through a heat exchanger 3, an air cooler 1 and a water cooler 4 and then is decompressed by a decompression valve, the reaction product enters a reaction product separation tank 1 for gas-liquid separation, bottom oil of the separation tank is sent into the absorption tower through a pump 6, rich gas at the top of the tank is pressurized through a rich gas compressor 2 and then is divided into three parts which respectively enter an oil-gas separation tank 2, one part of the three parts is mixed with the top gas of the desorption tower through a mixer 3, the mixture is cooled through the air cooler 2 and then is mixed with bottom oil of the absorption tower pumped out by an oil pump 7 at the bottom of the absorption tower in an oil-gas two-phase mixer 4, the mixture is cooled through a rich gas water cooler 5 and then enters the oil-gas separation tank 2 for oil-gas two-phase separation, and the other two parts are directly sent into the oil-gas separation tank 2 through the pumps 4 and 5. The gas phase separated by the oil-gas separation tank 2 enters an absorption tower, the gas at the top of the absorption tower is cooled by a dry gas heat exchanger 4 and a dry gas water cooler 6 and then enters a dry gas separation tank 3 for gas-liquid separation, the liquid phase enters a stabilization tower, and the dry gas is sent to a PSA device of a pressure swing adsorption hydrogen purification device for hydrogen recovery. The liquid phase of the oil-gas separation tank 2 is pumped out by a pump 8 and is divided into two parts by a divider, wherein one part is directly sent into a desorption tower, and the other part is heated by a heat exchanger 5 and then enters the desorption tower for desorption. The bottom oil of the desorption tower is cooled by a heat exchanger 5 and then sent to a stabilizing tower for fractionation. The gas phase at the top of the stabilizing tower is liquefied petroleum gas, and the stabilized gasoline at the bottom of the stabilizing tower is cooled by a water cooler 7 and then sent to a downstream refining separation section. The specific flow is shown in FIG. 3.

(3) The refining and separating process of the aromatic hydrocarbon comprises the following steps: the method comprises the steps of cooling stabilized gasoline flowing out of the bottom of a stabilized tower through a water cooler 7, sending the cooled stabilized gasoline to a benzene separation tower to separate benzene, cooling product benzene with the purity of 99.9% extracted from the top of the benzene separation tower through a water cooler 8, sending the cooled product benzene to a tank area for storage, sending produced liquid from the bottom of the benzene separation tower to a toluene separation tower through a pump 9 to separate toluene, cooling the cooled product toluene with the purity of 99.9% extracted from the top of the toluene separation tower through the water cooler 9, sending the cooled product toluene to the tank area for storage, sending the produced liquid from the bottom of the toluene separation tower to a xylene separation tower through a pump 10 to separate xylene, cooling xylene with the purity of 92% extracted from the top of the xylene separation tower through the water cooler 10, sending the cooled xylene separation tower to the tank area for storage, and sending heavy components at the bottom of the xylene separation tower to a waste liquid treatment place through a heavy component water cooler 11 after the heavy components are pumped out. The specific flow is shown in figure 4.

The invention adopts a catalytic hydrogenation method to process cracking carbon acanthopanax which is a byproduct of cracking ethylene into pentane, then couples n-pentane and methanol for aromatization, and adopts an acidic molecular sieve catalyst to obtain three high-added-value products of high-purity benzene, toluene and xylene through a series of reaction, absorption, stabilization and separation processes. The process can realize the direct preparation of high-purity triphenyl from the cracked ethylene byproduct, namely the cracked C five, and compared with the traditional method, the yield and the purity of the three are improved, so that the cracked C five fraction can be used as a fuel and a product with high added value, and the process has better economic and social benefits and market popularization prospects.

Drawings

FIG. 1 is a flow diagram of a process for cracking hydrocarbon;

FIG. 2 is a flow chart of a process of n-pentane-methanol coupled aromatization reaction;

FIG. 3 is a flow diagram of an absorption stabilization process for an aromatization unit;

FIG. 4 is a flow chart of the refining and separating process of aromatic hydrocarbons.

Detailed Description

Example 1

18750kg/hr cracked carbon five (mainly composed of pentapentene and a very small amount of four carbon components) and 829.233kg/hr hydrogen are fed by a feed pump, mixed gas is fed by a mixer, the inlet temperature of the mixed gas is 39 ℃, the inlet pressure is 3MPa, unsaturated diolefin is subjected to first-stage hydrogenation by a first-stage hydrogenation reactor to generate carbon pentamonoolefin, the outlet temperature of the first-stage reactor is 95 ℃, and the outlet pressure is 2.95MPa. Then, the mono-olefin is heated to 150 ℃ through a heat exchanger and a water cooler respectively and then enters a second-stage hydrogenation reactor, the inlet temperature of the second-stage reactor is 150 ℃, the inlet pressure is 2.95MPa, the mono-olefin is subjected to second-stage hydrogenation to generate carbon pentaalkane, the outlet temperature of the second-stage reactor is 295 ℃, and the outlet pressure is 2.9MPa. The carbon pentaalkane from the second-stage hydrogenation reactor is cooled by a heat exchanger and a water cooler, then enters a high-pressure separator to separate most of unreacted hydrogen, is compressed by a compressor and subjected to heat exchange by the heat exchanger, then enters a feeding part (a mixer) to circulate, and then enters a low-pressure separator to separate a small part of residual hydrogen, and then enters an isopentane separation tower. The carbon pentaalkane is separated by an isopentane separation tower, 7940.6kg/hr isopentane with the purity of 95 percent is obtained at the tower top and can be used as a raw material of a foaming agent, 10816.8kg/hr n-pentane with the purity of 98 percent is obtained at the tower bottom, and the n-pentane enters an aromatization reaction section after being cooled by a water cooler 3.

98 percent of n-pentane obtained from the hydrogenation section enters a feeding tank, then enters a mixer through a pump, meanwhile, 10700kg/hr 99.85 percent of methanol from the feeding tank is fed into the mixer through the pump, the two feeds are mixed and then enter a heat exchanger for preheating, and then enter an aromatization reactor for reaction after being heated by a heating furnace to generate carbon I, carbon II, carbon III, carbon IV, carbon V, carbon VI, carbon VII, carbon VIII and a small amount of carbon nine and carbon ten heavy components. ZSM-5 acidic molecular sieve catalysts are respectively filled in the reactors, the inlet temperature of the reactors is 550 ℃, and the inlet pressure is 0.3MPa. After methanol and n-pentane react in the aromatization reactors A and B, the outlet temperature is 450 ℃ and the outlet pressure is 0.3MPa. After being cooled by the heat exchanger, the air cooler and the water cooler respectively, the gas-liquid mixture enters an absorption stabilization section.

The absorption stabilizing system consists of an absorption tower, a desorption tower and a stabilizing tower, wherein a reaction product is cooled to 40 ℃ by a heat exchanger (90 ℃), an air cooler (60 ℃) and a water cooler, then the pressure is released by a pressure release valve, the reaction product enters a reaction product separation tank for gas-liquid separation, bottom oil of the separation tank is pumped into the absorption tower, rich gas at the top of the tank is pressurized by a rich gas compressor (2850 KPa) and then divided into three parts which respectively enter an oil-gas separation tank, one part of the rich gas is mixed with top gas of the desorption tower by a mixer, the mixture is cooled by the air cooler (60 ℃) and then mixed with bottom oil of the absorption tower pumped out by an oil pump at the bottom of the absorption tower in the mixer, the mixture is cooled by a rich gas water cooler (40 ℃) and then enters the oil-gas separation tank for oil-gas two-phase separation, and the rest two parts are directly pumped into the oil-gas separation tank by a pump. The gas phase (carbon one, carbon two, carbon three, carbon four, carbon five and hydrogen) separated by the oil-gas separation tank enters an absorption tower, the gas at the top of the absorption tower enters a dry gas separation tank for gas-liquid separation after being cooled by a dry gas heat exchanger (30 ℃) and a dry gas water cooler (12 ℃), the liquid phase enters a stabilization tower, and the dry gas is sent to a PSA device (pressure swing adsorption hydrogen purification device) to recover the hydrogen. The liquid phase of the oil-gas separation tank is divided into two parts by a pump separator and sent into a desorption tower, and the bottom oil of the desorption tower is sent into a stabilizing tower for fractionation after heat exchange (160 ℃) by a heat exchanger. The gas phase at the top of the stabilizing tower is liquefied petroleum gas, the stabilized gasoline at the bottom of the stabilizing tower exchanges heat with the feed firstly and then is divided into two streams, one stream is used as an absorbent and sent to an absorption tower, and the other stream is sent to a downstream device for aromatic hydrocarbon separation.

Stabilized gasoline flowing out of the bottom of a stabilized tower is cooled by a water cooler (125 ℃) and then sent to a benzene separation tower for benzene separation, 738.112kg/hr product benzene with the purity of 99.9% extracted from the top of the benzene separation tower is cooled by the water cooler (40 ℃) and then sent to a tank area for storage, toluene is separated from extracted liquid at the bottom of the benzene separation tower by a pump to the toluene separation tower, 5130.768kg/hr toluene with the purity of 99.9% extracted from the top of the toluene separation tower is cooled by the water cooler (40 ℃) and then sent to the tank area for storage, xylene is separated from extracted liquid at the bottom of the toluene separation tower by a pump to the xylene separation tower, 4530.447kg/hr xylene with the purity of 92% extracted from the top of the xylene separation tower is cooled by the water cooler (40 ℃) and then sent to the tank area for storage, and heavy component extracted from the bottom of the xylene separation tower is sent to a waste liquid treatment place by a heavy component cooler (40 ℃) after being pumped out by the pump.

Claims

1. A technology for producing triphenyl through aromatization of cracking carbon penta is characterized by comprising the following steps:

(1) Process for cracking carbon acanthopanax hydrogen

Mixing cracked carbon five and hydrogen fed by a feed pump 1 through a mixer 1, and feeding the mixture into a first-stage hydrogenation reactor after mixing, wherein the reactor is a fixed bed adiabatic reactor, the inlet temperature of the first-stage reactor is 36-40 ℃, the inlet pressure is 2.8-3.3 MPa, unsaturated diolefin is subjected to first-stage hydrogenation through the first-stage hydrogenation reactor to generate carbon pentamonoolefin, the outlet temperature of the first-stage reactor is 80-100 ℃, and the outlet pressure is 2.9-3.2 MPa; then mono-olefin respectively passes through a heat exchanger 1 and a water cooler 1 to be heated and then enters a second-stage hydrogenation reactor, the reactor is a fixed bed adiabatic reactor, the inlet temperature of the second-stage reactor is 140-165 ℃, the inlet pressure is 2.9-3.2 MPa, mono-olefin generates carbon pentaalkane after second-stage hydrogenation, the outlet temperature of the second-stage reactor is 280-300 ℃, and the outlet pressure is 2.8-3.0 MPa; the carbon pentaalkane from the second-stage hydrogenation reactor is cooled by a heat exchanger 1 and a water cooler 2, then enters a high-pressure separator to separate most of unreacted hydrogen and trace carbon tetraalkane, is compressed by a compressor 1 and exchanges heat with the heat exchanger 2, then enters a mixer 1 to circulate, and then enters a low-pressure separator to separate a small part of residual hydrogen and then enters an isopentane separation tower; separating the carbon pentaalkane by an isopentane separation tower, obtaining isopentane with the purity of 95 percent at the tower top as a raw material of a foaming agent, obtaining n-pentane with the purity of 98 percent at the tower bottom, cooling by a water cooler 3, and then entering an aromatization reaction section;

(2) N-pentane-methanol coupling aromatization reaction process

(1) The aromatization reaction process of the n-pentane methanol comprises the following steps: n-pentane obtained from a hydrogenation section enters a feeding tank 1, then enters a mixer 2 through a pump 2, meanwhile, methanol entering from the feeding tank 2 is sent into the mixer 2 through a pump 3, two feeds are mixed and then enter a heat exchanger 3 for preheating, and then enter aromatization reactors A and B for reaction after being heated through a heating furnace, wherein the reactors A and B are both fixed bed adiabatic reactors, ZSM-5 acidic molecular sieve catalysts are respectively filled in the reactors, the inlet temperature of the reactors is 540-570 ℃, and the inlet pressure is 0.25 MPa-0.31 MPa; the aromatization reaction of the methanol is an exothermic reaction, water is generated in the reaction process, and the catalyst is easily deactivated under the action of high temperature and steam, so that the yield of aromatic hydrocarbon is reduced; after methanol and n-pentane react in the aromatization reactors A and B, the outlet temperature is 430-460 ℃, and the outlet pressure is 0.27-0.32 MPa; after being respectively cooled by the heat exchanger 3, the air cooler 1 and the water cooler 4, the gas-liquid mixture enters an absorption stabilization section;

(2) the absorption stabilizing process of the aromatization device comprises the following steps: the absorption stabilizing system consists of an absorption tower, a desorption tower and a stabilizing tower, a reaction product is cooled to 30-50 ℃ through the previous working section and then is decompressed by a decompression valve, the reaction product enters a reaction product separation tank 1 for gas-liquid separation, bottom oil of the separation tank is sent into the absorption tower through a pump 6, rich gas at the top of the tank is pressurized by a rich gas compressor 2 and then is divided into three parts which respectively enter an oil-gas separation tank 2, one part of the three parts is mixed with the top gas of the desorption tower through a mixer 3, the mixture is cooled by an air cooler 2 and then is mixed with bottom oil of the absorption tower pumped out by an oil pump 7 at the bottom of the absorption tower in an oil-gas mixer 4, the mixture is cooled by a rich gas water cooler 5 and then enters the oil-gas separation tank 2 for oil-gas two-phase separation, and the rest two parts are directly sent into the oil-gas separation tank 2 through pumps 4 and 5; the gas phase separated by the oil-gas separation tank 2 enters an absorption tower, the gas at the top of the absorption tower is cooled by a dry gas heat exchanger 4 and a dry gas water cooler 6 and then enters a dry gas separation tank 3 for gas-liquid separation, the liquid phase enters a stabilization tower, and the dry gas is sent to a PSA device of a pressure swing adsorption hydrogen purification device for hydrogen recovery; the liquid phase of the oil-gas separation tank 2 is pumped out by a pump 8 and is divided into two parts by a divider, wherein one part is directly sent into a desorption tower, and the other part is heated by a heat exchanger 5 and then enters the desorption tower for desorption; cooling the bottom oil of the desorption tower by a heat exchanger 5, and then sending the bottom oil to a stabilizing tower for fractionation; the gas phase at the top of the stabilizing tower is liquefied petroleum gas, and the stabilized gasoline at the bottom of the stabilizing tower is cooled by a water cooler 7 and then sent to a downstream refining separation section;

(3) the refining and separating process of the aromatic hydrocarbon comprises the following steps: the method comprises the steps of cooling stable gasoline flowing out of the bottom of a stable tower through a water cooler 7, sending the cooled stable gasoline to a benzene separation tower to separate benzene, cooling a product benzene with the purity of 99.9% extracted from the top of the benzene separation tower through a water cooler 8, sending the cooled stable gasoline to a tank area to be stored, sending a produced liquid at the bottom of the benzene separation tower to a toluene separation tower through a pump 9 to separate toluene, cooling the toluene with the purity of 99.9% extracted from the top of the toluene separation tower through the water cooler 9, sending the cooled stable gasoline to the tank area to be stored, sending the produced liquid at the bottom of the toluene separation tower to a xylene separation tower through a pump 10 to separate xylene, cooling the xylene with the purity of 92% extracted from the top of the xylene separation tower through the water cooler 10, sending the cooled xylene to the tank area to be stored, and sending heavy components at the bottom of the xylene separation tower to a waste liquid treatment place through a heavy component water cooler 11 after being extracted from the top of the xylene separation tower through the pump 11.