CN1250494C - Technological process for catalyzing dry gas to prepare ethylbenzene - Google Patents

Abstract

The invention discloses a technological process for preparing ethylbenzene from catalytic dry gas, which has the advantages that pipelines are not corroded, the recovery rate of benzene is over 99.5%, and the energy consumption of the device is at the lowest level in China. It includes water washing tower, alkylation reactor, crude separation tower, absorption tower, benzene tower, toluene removal tower, ethylbenzene tower, polyethylbenzene removal tower, diethylbenzene tower, heat exchanger, pump, tank, catalytic dry The gas is firstly washed by a water washing tower to remove the MDEA carried in the dry gas, and then enters the alkylation reactor for reaction. The reaction product passes through a heat exchanger and enters the rough separation tower. The non-condensable gas at the top of the rough separation tower is condensed and cooled to 5~ At 20°C, it enters the absorption tower, and the crude bottom liquid is pumped and then enters the benzene tower, the toluene removal tower, the ethylbenzene tower, the polyethylbenzene removal tower, and the diethylbenzene tower to sequentially separate the circulating benzene, toluene, ethylbenzene, Propylbenzene, heavy components and diethylbenzene, the anti-alkylation reaction products enter the benzene tower after heat exchange. The invention is suitable for reforming the existing technological process of producing ethylbenzene from catalytic dry gas.

Description

Process flow of catalytic dry gas to ethylbenzene

Technical field:

The invention relates to the technical field of producing ethylbenzene in petrochemical industry, and to be precise, it is a technical process for producing ethylbenzene by catalytic dry gas.

Background technique:

Benzene is an important organic chemical raw material, mainly used in the production of styrene. The strong demand for styrene in the market has driven the continuous growth of ethylbenzene production. Therefore, it is necessary to open up new sources of raw materials used in the production of ethylbenzene and find New and cheaper routes of production are of great importance.

Ethylbenzene is used as the raw material of styrene monomer, 90% of which is produced by alkylation reaction of benzene and high-concentration ethylene. The source of ethylene raw materials is of great significance to the development of the ethylbenzene industry, which is related to the economic benefits and normal operation of the ethylbenzene industry. Especially in my country, the crude oil is heavy, the light oil rate is low, and the source of ethylene raw materials is restricted by the nature of petroleum resources. Therefore, it is necessary to make full use of various forms and different concentrations of ethylene, especially low-concentration ethylene, to alleviate the shortage of ethylene raw materials in my country.

Catalytic cracking is an important process for the deep conversion of heavy oil in refineries and to improve economic benefits, and it is also an important source of dry gas with low concentration of ethylene. There are dozens of sets of catalytic cracking units in my country, with an annual output of nearly one million tons of dry gas. Dry gas contains 10% to 20% ethylene, and most of them are still used as fuel for heating furnaces together with other dry gas components, which is undoubtedly a great waste of useful resources. If the ethylene in the dry gas is used to produce ethylbenzene, it will not only expand the source of ethylene raw materials, partially alleviate the long-term contradiction of ethylene in short supply in my country, but also open up a new way for the comprehensive utilization of refinery dry gas, and significantly increase the economy of enterprises. benefit.

Styrene is generally produced by dehydrogenation of ethylbenzene. In the past, pure ethylene and benzene were used to synthesize ethylbenzene, but the cost of ethylbenzene was high and uneconomical.

Synthesizing ethylbenzene from ethylene in cheap dry gas is a very meaningful topic. It can not only make full use of existing dry gas resources, but also greatly reduce the cost of ethylbenzene and styrene products, which has far-reaching implications for the entire petrochemical industry. significance.

Currently, the technological process for preparing ethylbenzene from catalytic dry gas is roughly divided into two types: one is the use of catalytic rectification (absorption) process, dry gas and fresh benzene enter the catalytic rectification (absorption) tower from the bottom and top of the tower respectively, The catalytic rectification (absorption) tower uses a plate tower or a packed tower to distribute the catalyst in the tower. The benzene reacts while absorbing the dry gas. The unreacted tail gas is discharged from the top of the tower, and the reaction product ethylbenzene and benzene is obtained at the bottom of the tower. , followed by subsequent separation to obtain ethylbenzene product.

The other is the bubbling bed process, in which the catalyst is completely submerged in benzene, and the dry gas passes through the submerged catalyst in the form of bubbling, and reacts with the catalyst to form ethylbenzene, which is then subjected to subsequent separation to obtain the ethylbenzene product.

Catalytic dry gas production of ethylbenzene generally uses β zeolite molecular sieve catalysts. In the above two process experiments, it was found that there were many side reactions, catalyst deactivation and short life. After repeated research and exploration, it was found that the contact between the catalyst and the gas phase is the direct cause of this consequence. When the dry gas contacts the catalyst, small molecular hydrocarbons will enter the micropores of the zeolite and undergo side reactions such as polymerization, which will cause the catalyst channel to be blocked and lose active, shortening the life of the catalyst.

The catalytic rectification (absorption) process has the advantages of high conversion rate, good selectivity, and less amount of catalyst, but this process cannot avoid the contact between the catalyst and the gas phase, so the life of the catalyst cannot be guaranteed. This is determined by the mechanism of the catalytic rectification (absorption) process. In the catalytic rectification (absorption) process, a packed fixed bed structure and a plate tower structure can be used. For the packed fixed bed structure, a large packing spray density is required to protect the catalyst from direct contact with the gas phase. When there are insurmountable problems in this structure: 1. Due to the limitation of bed porosity, the packing spray density cannot be too large, otherwise the tower will not be able to operate normally; 2. The gas phase always passes through the bed, so the catalyst cannot be guaranteed. Absolutely no contact with the gas phase. The plate tower structure can ensure that the catalyst is bubbled in the liquid phase, and the gas phase does not pass through the catalyst. However, due to the entrainment of the gas phase by the liquid phase and the heat of reaction, the gas phase generated by the gasification of the liquid phase may contact the catalyst. It can be seen from the above that the catalytic rectification (absorption) process cannot guarantee the catalyst life.

The bubbling bed process can completely bubble the catalyst in the liquid phase, which can protect the catalyst to a certain extent. However, since the reaction of catalytic dry gas to ethylbenzene is controlled by absorption, and the absorption efficiency of the bubbling bed is very low, it has the disadvantages of low conversion rate, poor selectivity, and large amount of catalyst. At the same time, the gas phase in this process still has to pass through the catalyst bed, so it cannot be guaranteed that the catalyst will not be in contact with the gas phase at all. It can be seen that the bubbling bed process cannot guarantee the catalyst life. China Patent No.: 87105054 discloses an invention patent titled "Process of Alkylation of Dilute Ethylene to Ethylbenzene and Zeolite Catalyst Used therein", which is a kind of alkylation of benzene and ethylene, especially suitable for the use of low-concentration Ethylene refinery tail gas (such as catalytic cracking dry gas) is used as a catalyst for the benzene alkylation process of the reaction raw material. It is jointly applied by China Petrochemical Corporation, Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Fushun Petrochemical Company. Mobil Petroleum Co., Ltd. applied for an invention patent No. 93112744.0 in China in 1993, named "Production of Ethylbenzene". Benzene undergoes an alkylation reaction. The diethylbenzene by-product of the gas-phase alkylation reaction is separated from the ethylbenzene product, and then carried out with benzene in the liquid phase for alkylation transfer to further produce more ethylbenzene. Zeolite β can be used as a catalyst. Chinese patent number: 99124797 discloses an invention patent titled "method and equipment for producing ethylbenzene by catalytic distillation of benzene and refinery dry gas". The processing step is to simultaneously make benzene and ethylene carry out a gas-liquid-solid three-phase alkylation reaction in a solid catalyst amount in a catalytic distillation tower and make the reaction product mixture undergo distillation separation at the same time, and simultaneously the catalyst and the distillation packing The performance, configuration and filling method of the tank must meet the given requirements. In the above method, the raw material dry gas directly enters the reactor without treatment. Chinese patent number: 00131924.8 discloses an invention patent named "process of producing ethylbenzene from catalytic dry gas". It first uses an absorbent to absorb the ethylene in the dry gas, and then enters the fulvene liquid into the reactor for further processing. The liquid phase reaction can ensure that the reaction is carried out in the liquid phase, so that the catalyst is not in contact with the gas phase at all, thus ensuring the life of the catalyst. It overcomes the disadvantages of contacting the gas phase with the catalyst under process conditions such as catalytic rectification (absorption) bubbling bed, many side reactions, easy reduction of catalyst activity, and short service life.

The No. 2 Petroleum Plant of Fushun Petrochemical Company, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, and Luoyang Petrochemical Engineering Co., Ltd. once jointly developed the catalytic cracking dry gas production of ethylbenzene technology, and built a 3×10 ⁴ t/a dry gas system in the No. 2 Petroleum Plant in 1993 Ethylbenzene unit, steaming successfully once. After ten years of operation, all indicators have reached the development goals. In 1999, the third-generation technology experimental device was built.

But at that time, the 3×10 ⁴ t/a dry gas to ethylbenzene plant was just an industrial experimental device, and the energy utilization of the device was not reasonable. The original design situation: the catalytic dry gas does not need to be refined and directly enters the alkylation reactor. Because the catalytic dry gas contains H ₂ S, the reactor and pipeline are severely corroded, and even the reactor is blocked; the circulating benzene only undergoes one heat exchange (with the reaction product ) and then heated by a circulating benzene heating furnace to reach vaporization until the reaction temperature, and the reaction product will be cooled to 40°C before entering the absorption system, and finally heated to the feed temperature to enter the rectification system; the loading of the catalyst in the alkylation reactor is divided It is 5 stages, and the energy consumption is as high as 3.75 million kcal/ton of ethylbenzene. Later, Luoyang Petrochemical Engineering Company designed a 10×10 ⁴ t/a dry gas ethylbenzene plant for Dalian Petrochemical Company. higher than this number.

Invention content:

The purpose of the present invention is to provide a technical process for preparing ethylbenzene from catalytic dry gas, which adopts dry gas washing and absorption process to remove MDEA after desulfurization, so as to protect equipment, protect equipment and pipelines from corrosion, and protect catalysts from corrosion at the same time. poisoned. The tail gas is absorbed at low temperature, so that the recovery rate of benzene can reach more than 99.5%. The energy consumption of the device is the lowest level in China, which is 980,000 kcal/ton of ethylbenzene, and the ethylbenzene product has reached the national high-grade product standard.

(1) Raw material processing part

Previous process: using non-desulfurized dry gas, long-term operation of pipelines, severe corrosion of equipment, and excessive pressure drop of the reaction system, reaching 0.3MPa at the maximum.

The present invention uses desulfurized dry gas to reduce corrosion of pipelines and equipment, but the desulfurized dry gas contains MDEA, which may easily cause poisoning of the hydrocarbonation catalyst and reduce the reaction activity, and the MDEA needs to be removed by a water washing process.

(2) Reaction part

Previous process:

(1) The hydrocarbonation reactor is filled with equal volume in five stages, and the dry gas is injected in three stages.

(2) The alkylation reactant is cooled to 40°C and put into the absorption tower.

(3) The high-temperature alkylation reactants are used to heat and gasify circulating benzene, and the circulating benzene heating furnace is used to increase the temperature of circulating benzene.

(4) The inlet material of the anti-alkylation reactor needs to be heated with a heat carrier.

this invention:

(1) The hydrocarbonation reactor adopts four stages of unequal filling, and it can also be filled with the same amount, and the dry gas is injected in three stages.

(2) The alkylation reactant is cooled to about 140°C and enters the crude separation tower.

(3) The high-temperature alkylation reactant is used to heat the inlet material of the circulating benzene and anti-alkylation reactor. The vaporization of the circulating benzene is completed by heating the oil and gas at the top of the benzene tower. The circulating benzene heating furnace is mainly used for starting work and when the ethylene concentration is low. , When the ethylene concentration is higher than 18% (body), the circulating benzene heating furnace can be shut down.

(4) The inlet material of the reverse alkylation reactor is heated to the reaction temperature with the alkylation reactant.

(3) Absorption part

Previous process:

(1) The alkylation reactant is cooled to 40°C for flash evaporation and absorption.

(2) The alkylation reactants are flashed and absorbed twice under different pressures.

(3) The absorbent circulates in large quantities in the system.

(4) After heat exchange between the rich absorbent and the alkylation reactant, the non-condensable gas is removed in the stabilizing tower.

(5) A reboiler is installed at the bottom of the stabilizing tower, and the material at the bottom of the stabilizing tower is fed into the benzene tower.

this invention:

(1) The alkylation reactants are cooled to about 140°C and put into the crude separation tower for vapor-liquid separation.

(2) The top of the crude separation tower is cooled to 40°C, the non-condensable gas at 40°C is further cooled to 10°C, and the non-condensable gas at 10°C enters the absorption tower.

(3) The absorbent is diethylbenzene, and the rich absorbent is directly put into the anti-alkylation tank, mixed with circulating benzene and then sent into the anti-alkylation reactor, and the absorbent is not circulated in the system.

(4) The inlet material of the reverse alkylation reactor is heated to the reaction temperature with the alkylation reactant.

(5) A reboiler is installed at the bottom of the coarse separation tower, and the material at the bottom of the coarse separation tower is transferred into the benzene tower after heat exchange, and the non-condensable gas is removed at the top of the benzene tower.

(4) Product separation part

Previous process:

(1) Each tower of the product separation part adopts atmospheric pressure separation, and only the ethylbenzene tower can generate steam.

(2) Toluene is intermittently extracted from the side line of the benzene tower, entraining part of benzene.

(3) The absorbent is the bottom material of the ethylbenzene tower, and it circulates in a large amount in the system, and the equipment specifications such as the stabilizing tower, the benzene tower, and the ethylbenzene tower are relatively large.

(4) The polyethylbenzene removal tower adopts decompression, and no steam occurs at the top of the tower.

this invention:

(1) Each tower in the product separation part adopts pressure separation and steam can be generated at the top of each tower.

(2) The non-condensable gas is pulled out from the top of the benzene tower, and the recycled benzene comes out from the side line of the benzene tower, and the toluene is drawn out from the top of the ethylbenzene tower, and the ethylbenzene product comes out from the side line of the ethylbenzene tower.

(3) The absorbent is diethylbenzene, which is a process material and does not circulate in the system. The equipment specifications such as the crude separation tower, benzene tower, and ethylbenzene tower are relatively small, and the heat used for heating is less.

(4) The polyethylbenzene removal tower adopts normal pressure operation, steam can be generated at the top of the tower, and there is no vacuum pumping system.

(5) A pressure difference is formed between the benzene tower and the alkylation reactor to utilize the oil and gas in the benzene tower to heat and vaporize the circulating benzene.

The advantages of the present invention are:

(1) In the existing process flow, the raw material dry gas directly enters the reactor without treatment, which seriously corrodes the equipment and pipelines. The present invention adopts the dry gas washing and absorption process to remove the MDEA after desulfurization, so as to protect the equipment, Pipelines are protected from corrosion while protecting catalysts from poisoning.

(2) The reaction product enters the crude separation tower at about 140°C after heat exchange, and the heat energy is rationally used, that is, the heating process after the reaction product is cooled is avoided.

(3) Increase the pressure of the benzene tower, use the heat of the oil gas at the top of the tower to heat the circulating benzene, make it reach the reaction conditions, greatly reduce the load of the heating furnace, thereby saving energy consumption.

(4) Use low temperature to absorb tail gas, so that the recovery rate of benzene can reach more than 99.5%.

(5) The alkylation reactor adopts four stages of unequal filling.

(6) The energy consumption of the device is the lowest level in China, which is 980,000 kcal/ton of ethylbenzene, and the ethylbenzene product has reached the national excellent standard.

Description of drawings:

Figure 1 is a schematic diagram of the process flow of catalytic dry gas production of ethylbenzene.

Figure 2 is a schematic diagram of the process flow of catalytic dry gas production of ethylbenzene.

In the accompanying drawings, 1 is a water washing tower, 2 is a dry gas separator tank, 3 is an alkylation reactor, 4 is a circulating benzene heating furnace, 5 is a circulating benzene buffer tank, 6 is an anti-alkane feed tank, and 7 is an anti-hydrocarbon Reactor, 8 is a crude separation tower, 9 is an absorption tower, 10 is a benzene tower, 11 is a toluene removal tower, 12 is an ethylbenzene tower, 13 is a polyethylbenzene removal tower, and 14 is a diethylbenzene tower, (1) It is fresh water, (2) is dry gas, (3) is fresh benzene, (4) is tail gas, (5) is ethylbenzene tower feed, (6) is absorbent, (7) is propylbenzene, (8) ) is a high boiler, (9) ethylbenzene, (10) is toluene.

Detailed ways:

The characteristics and positive effects of the present invention can be manifested from the following application examples.

The invention includes a reaction part, an absorption part and a product separation part, and is characterized in that: the catalytic dry gas is eluted out of MDEA through a water washing tower (1) and then enters into a dry gas separator tank (2) and enters an alkylation reactor (3) in four ways The reactant enters the crude separation tower (8) after heat exchange, and the anti-alkylation material comes from the absorption tower (9), mixes with benzene and enters the anti-alkylation reactor (7) for reaction, and the reaction product is mixed with the crude The material at the bottom of the sub-tower (8) enters the benzene tower (10) respectively. The hydrocarbonation reaction product is cooled to 100-150°C through a series of heat exchanges and then enters the crude fractionation tower (8). The oil and gas at the top of the tower is partially condensed by the condenser and then enters the top reflux tank of the crude fractionation tower, and the condensate enters the top of the crude fractionation tower As reflux, the non-condensable gas enters the condenser through the pressure control valve and cools to 5-15°C, the gas phase enters the absorption tower (9), and the liquid phase flows into the top reflux tank (integrated type) of the rough separation tower, and the bottom material of the coarse separation tower After being pressurized by the pump, it enters the benzene tower (10) for separation, and the non-condensable gas condensed to 5-15°C at the top of the crude separation tower enters the absorption tower (10) and contacts with the absorbent ((6)) from top to bottom , to absorb heavy components. The tail gas is discharged from the top of the absorption tower, part of it is used as fuel in the device, and the rest enters the pipeline network. The condensate is used as reflux, and the non-condensable gas enters the crude separation column (8). Benzene is extracted from the side line of the benzene tower (10), part of which is sent into the circulating benzene tank (5), and the other part is sent into the anti-alkylation tank (6), and the toluene is extracted from the stripping section into the detoluene tower (11). The material enters the ethylbenzene tower (12), and the topped ethylbenzene is steamed out from the tower top. After cooling, a part is used as reflux, and the other part is used as the feed of the toluene removal tower (11). After being separated by the toluene removal tower (11), toluene is removed from The top of the toluene tower is steamed out, part of it is used as reflux after cooling, and the other part is sent to the toluene tank, wherein the delivery of toluene can be continuous or intermittent, and a part of ethylbenzene is steamed out from the bottom of the toluene removal tower (11), and sent into the toluene tank after cooling. Ethylbenzene tank, most of ethylbenzene is taken out from ethylbenzene tower (12) side line, sends into ethylbenzene tank as product after cooling. The material at the bottom of the tower enters the polyethylbenzene removal tower (13) after being pressurized, diethylbenzene, propylbenzene etc. are steamed out from the tower top, a part is used as reflux, and another part is used as the feedstock of the diethylbenzene tower (14), and the bottom of the tower is High boilers, wherein the high boilers can be sent out continuously or intermittently, propylbenzene is steamed from the top of the diethylbenzene tower (14), a part is used as reflux, and the other part is cooled as a product out of the device, wherein the propylbenzene can be sent out It can be operated continuously or intermittently. The diethylbenzene at the bottom of the diethylbenzene tower enters the absorption tower (9) through heat exchange and cooling to 20-50°C as an absorbent.

The catalytic dry gas at 1.1MPa and 40°C enters the washing tower from the system for washing, and the washing water is recycled fresh water (with replenishment), most of the MDEA in the gas is removed, and the concentration of MDEA in the dry gas after washing is reduced to below 1ppm.

The washed dry gas enters the dry gas liquid separation tank and then enters the alkylation reactor in three routes. Each route is equipped with cascade adjustments for flow rate and reaction bed temperature, so that each strand of dry gas can be distributed according to regulations. The reaction was carried out under the conditions of 0.95MPa, 410°C, and benzene:ethylene ratio of 5:1. The reaction product undergoes secondary heat exchange with circulating benzene at 0.85MPa and 380°C, heat exchange with anti-alkylation feedstock, and primary heat exchange with circulating benzene, then heat exchange with desalted water at 0.7MPa and 235°C to generate 0.3MPa saturated steam , exchange heat with benzene tower feed at 0.65MPa, 187°C, and then enter the crude separation tower at 0.6MPa, 140°C, and diethylbenzene at 1.4MPa, 252°C from the absorption tower enters the anti-alkane feedstock Tank, 1.2MPa, 177°C circulating benzene enters the anti-alkylation material tank from the circulating benzene tank, and is pumped out after being mixed with the anti-alkylation material to pressurize to 3.5MPa, 185.4°C, and heat exchange with the alkylation reaction product to 260 ℃ into the anti-alkylation reactor for anti-alkylation reaction, the reaction conditions are 3.4MPa, 260 °C, and the reaction product enters the benzene tower through the pressure control valve.

The 0.6MPa, 140°C alkylation reaction product and the 1.3MPa, 40°C benzene tower top non-condensable gas enter the crude separation tower respectively. At 0.55MPa and 106.5°C, the oil and gas at the top of the tower is cooled to 39°C by the condensation cooler at the top of the crude separation tower and enters the top reflux tank. The gas phase is cooled to 10°C by the feed cooler of the absorption tower. The gas phase enters the absorption tower, and the liquid phase enters the top of the tower. The reflux tank (integrated type), the reflux is pumped out by the reflux pump at the top of the crude fractionation tower, and then returned to the top of the crude fractionation tower as reflux after cascade adjustment of the flow rate and the liquid level of the reflux tank. , 120°C, after heat exchange with the alkylation reaction product, it enters the benzene tower at 170°C, and the non-condensable gas entering the absorption tower is in countercurrent contact with the absorbent from top to bottom, absorbing heavy components such as benzene, and the tail gas is from the top of the absorption tower At 0.4MPa and 28.5°C to the system, the bottom liquid of the absorption tower is pressurized at 0.45MPa and 17.4°C by the anti-alkylation feed pump to exchange heat with the absorbent at 0.45MPa and then enters the anti-alkylation tank at 1.4MPa and 200°C.

The steam evaporated from the top of the benzene tower exchanges heat with the circulating benzene at 1.38MPa and 194°C to vaporize the circulating benzene, and then generates 0.3MPa saturated steam at 187.5°C, condenses and cools to 157°C and enters the reflux tank at the top of the benzene tower. The benzene tower reflux pump pumps back to the top of the benzene tower as reflux, and the gas phase in the benzene tower reflux tank is cooled to 40°C by a top-topped benzene cooler and enters the crude separation tower, and the condensate flows into the reflux tank. 1.38MPa, 196.5°C circulating benzene is drawn from the side line of the benzene tower and enters the circulating benzene tank. The bottom of the benzene tower enters the ethylbenzene tower at 1.45MPa and 277.5°C.

The ethylbenzene tower top gas at 0.23MPa and 167.8℃ enters the ethylbenzene tower top reflux tank at 159.5℃ after generating 0.3MPa saturated steam. As topped ethylbenzene, it is sent to the toluene removal tower. The ethylbenzene at 169.3°C is drawn from the side line of the ethylbenzene tower and sent to the ethylbenzene product tank after being cooled to 40°C. The bottom product of the ethylbenzene tower is pumped out by the polyethylbenzene pump at 214.4°C and sent to the polyethylbenzene removal tower.

The 0.23MPa, 132.3°C detoluene tower top gas is cooled to 122°C by the toluene removal tower top condensing cooler and enters the toluene removal tower top reflux tank. The liquid phase is drawn out by the toluene removal reflux pump. After being cooled to 40°C, it is sent to the toluene tank. The ethylbenzene at the bottom of the toluene removal tower is pumped out at 171.2°C by the bottom pump of the toluene removal tower, and is cooled to 40°C by an ethylbenzene cooler and sent to the ethylbenzene product tank.

The 0.18MPa, 204.2°C overhead gas of the POE removal tower enters the POE removal tower reflux tank at 194.4°C after generating 1.0 MPa saturated steam, and the liquid phase is pumped out through the POE removal tower reflux pump, and part of it is returned as reflux The top of the polyethylbenzene tower is removed, and the other part is sent to the diethylbenzene tower as the feed of the diethylbenzene tower. The high boilers at the bottom of the polyethylbenzene removal tower are drawn out by the commercial boiling pump at 236°C, cooled to 40°C by the high boiler cooler and sent to the high boiler tank.

The diethylbenzene tower top gas at 0.43MPa and 236.3°C generates 1.0MPa saturated steam and enters the diethylbenzene tower reflux tank at 220.7°C, the liquid phase is drawn out by the diethylbenzene tower reflux pump, and part of it is returned as diethylbenzene tower top reflux The diethylbenzene tower, the other part is cooled to 40°C by a propylbenzene cooler and sent out to the device. The bottom product of the diethylbenzene tower is pumped out by the absorbent pump at 0.44MPa and 252°C as an absorbent and sent to the absorption tower.

The invention is particularly suitable for transforming the existing technological process of producing ethylbenzene from catalytic dry gas.

Claims (11)

1, a kind of catalysis drying gas process for preparing ethylbenzene flow process, it comprises water wash column (1), alkylation reaction device (3), dealkylation reaction device (7), rough segmentation tower (8), absorption tower (9), benzene tower (10), take off toluene tower (11), ethylbenzene tower (12), de multi-ethyl tower (13), diethylbenzene tower (14), a series of interchanger, pump, jar, it is characterized in that: catalysis drying gas is at first washed through water wash column (1), deviate from the MDEA that carries in the dry gas, control MDEA content is below 1ppm, enter alkylation reaction device (3) reaction then, reaction product is through a series of interchanger heat exchange, enter rough segmentation tower (8), rough segmentation cat head non-condensable gases is cooled to 5-20 ℃ through condensation, enter absorption tower (9), liquid enters benzene tower (10) at the bottom of the rough segmentation tower after the pump pressurization, take off toluene tower (11), ethylbenzene tower (12), de multi-ethyl tower (13), diethylbenzene tower (14) order is isolated recycle benzene and is entered dealkylation reaction device (7) reaction together, and the dealkylation reaction product enters benzene tower (10) after heat exchange.

2, a kind of catalysis drying gas process for preparing ethylbenzene flow process according to claim 1 is characterized in that: increase adsorption tower behind the dry gas water wash column.

3, a kind of catalysis drying gas process for preparing ethylbenzene flow process according to claim 1, it is characterized in that: benzene tower (10) tower top temperature is controlled at 160-260 ℃, and pressure-controlling is at 0.5-2.0MPa; Utilize benzene tower (10) cat head oil gas heating cycle benzene, make its vaporization, utilize alkylation reaction product heating cycle benzene again, make its near or reach temperature of reaction.

4, a kind of catalysis drying gas process for preparing ethylbenzene flow process according to claim 1, it is characterized in that: the alkylation reaction product enters the rough segmentation tower after a series of heat exchange, and the reaction product temperature is controlled at 100-150 ℃ and enters the rough segmentation tower.

5, a kind of catalysis drying gas process for preparing ethylbenzene flow process according to claim 1 is characterized in that: ethylbenzene is extracted out from the side line of ethylbenzene tower as product.

6, a kind of catalysis drying gas process for preparing ethylbenzene flow process according to claim 1, it is characterized in that: diethylbenzene directly enters dealkylation reaction as absorption agent.

7, a kind of catalysis drying gas process for preparing ethylbenzene flow process according to claim 1 is characterized in that: the steam of the low potential temperature heat generation different grades of said a series of interchanger utilizations, and also with other low-temperature receiver heat exchange.

8, a kind of catalysis drying gas process for preparing ethylbenzene flow process according to claim 1 is characterized in that: the filling of catalyzer can segmentation in the alkylation reaction device, adopts the inequality filling.

9, a kind of catalysis drying gas process for preparing ethylbenzene flow process according to claim 1, it is characterized in that: said ethylbenzene tower, de multi-ethyl tower, diethylbenzene tower, they are operated in the 0.1-0.6MPa scope, according to the temperature of cat head oil gas 0.3MPa or 1.0MPa saturation steam can take place.

10, a kind of catalysis drying gas process for preparing ethylbenzene flow process according to claim 1 is characterized in that: the propyl benzene of sending from the diethylbenzene reflux pump to carry out heat exchange with low-temperature receiver or other low-temperature receivers of this device according to what of heat.

11, a kind of catalysis drying gas process for preparing ethylbenzene flow process according to claim 5 is characterized in that: the ethylbenzene of extracting out from the ethylbenzene tower side line to carry out heat exchange with low-temperature receiver or other low-temperature receivers of this device according to what of heat.

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