A device for preparing ethylbenzene by dry gas-liquid phase process containing ethylene

Abstract

The invention discloses a device for preparing ethylbenzene by liquid phase method of ethylene-containing dry gas in the field of petrochemical technology, comprising an ethylene-containing dry gas pretreatment unit, a propylene removal unit, a fresh benzene treatment unit, an alkylation reaction unit and a product separation unit, and each unit is connected by a pipeline. The invention adopts liquid phase alkylation reaction to produce ethylbenzene, avoids direct contact between gas phase ethylene and catalyst, and delays coking and deactivation of catalyst.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical industry, in particular to a device for preparing ethylbenzene by a dry gas-liquid phase method containing ethylene. Technical Background

[0002] Ethylbenzene is the raw material for producing styrene, and styrene is mainly produced by dehydrogenation. The main production technology routes of ethylbenzene are liquid phase method and gas phase method. The liquid phase method usually adopts the pure ethylene route, and the gas phase method usually adopts the dilute ethylene dry gas route. The source of ethylbenzene raw materials is related to the economic benefits and development of the enterprise. Making full use of the refinery's own ethylene-containing dry gas to produce ethylbenzene is beneficial to improving the economic benefits of the enterprise and promoting the rapid development of the ethylbenzene-styrene industry.

[0003] As the tail gas of the catalytic unit, the catalytic dry gas of the refinery is usually directly burned as fuel gas, and the utilization rate is low. The catalytic dry gas is rich in ethylene. Burning it as fuel gas will cause serious waste of ethylene resources. Using the ethylene in the catalytic dry gas to produce ethylbenzene can improve the utilization rate of the catalytic dry gas and effectively reduce the production cost of the ethylbenzene unit. The gas phase process has a high reaction temperature and many side reactions. There are many impurity components such as xylene and propylbenzene in the product. The quality of the ethylbenzene product is relatively poor and the energy consumption is large. The liquid phase process has mild reaction conditions, and the ethylbenzene product produced is of better quality and lower energy consumption than the gas phase process. In addition to a certain amount of ethylene components, the catalytic dry gas also contains a large amount of hydrogen, methane, ethane, nitrogen and other components. It is difficult to operate the alkylation reactor under liquid phase conditions. The catalyst of the liquid phase process is very easy to coke and deactivate when there is a gas phase. At present, most of the industrialized catalytic dry gas to ethylbenzene units in China adopt the gas phase process route.

[0004] CN101665398A proposes a method for refining ethylene-containing raw gas for ethylene-to-ethylbenzene process. The method sequentially sets up a three-tower process of an absorption tower, an ethylene desorption tower and a propylene desorption tower. The absorption tower uses benzene as an absorbent. The saturated absorbent after absorbing propylene in the raw gas enters the ethylene desorption tower and the propylene desorption tower in sequence. The gas at the top of the ethylene desorption tower returns to the entrance of the absorption tower, and the absorbent desorbed in the propylene desorption tower returns to the absorption tower for recycling. The method can increase the propylene removal rate in the raw gas to more than 98% under the condition that the propylene volume content in the raw gas is as high as 3%, and the ethylene loss rate is less than 2%. The method solves the shortcomings of the prior art of non-continuous operation of the ethylene raw gas pretreatment process, high ethylene loss rate, and low propylene removal rate.

[0005] CN102746084A proposes a raw material processing method for a process of producing ethylbenzene from ethylene raw materials. After the ethylene raw material gas passes through an absorption-desorption device, the gas enters an ethylbenzene reaction part, and the desorbed gas enters a liquid separation device after being cooled. After liquid separation, a part of the condensate containing absorbent and heavy hydrocarbons returns to the absorption-desorption device for use as a circulating absorbent, and the other part is sent to a product separation part for processing. The method has a simple process flow and low investment, and is suitable for the existing process flow of producing ethylbenzene from dry gas.

[0006] CN106278797A proposes a method for producing ethylbenzene from catalytic dry gas. The method is a gas-phase ethylbenzene production process. After heat exchange, the catalytic dry gas containing ethylene is divided into N strands and enters each section of the catalyst bed of the alkylation reactor, and the flow rate of each strand is the same; the raw benzene is added from the first section of the alkylation reactor or divided into N strands and added to the alkylation reactor in sections, and the flow rate of each strand is the same. Ethylene and benzene are contacted and reacted in each section of the catalyst bed. The inlet temperature of each section of the catalyst bed is 300-400°C, and the bed temperature rise is 10-25°C. By controlling the inlet temperature of the catalytic dry gas, the method solves the problems of uneven reactor bed temperature rise, low ethylene recovery rate and low catalyst utilization rate caused by large changes in the ethylene concentration contained in the catalytic dry gas in the previous processes (such as CN200510105256.X, CN1557794A, etc.). However, the process method has the problems of high benzene-olefin ratio, low ethylene conversion rate, high reaction temperature, many by-products, high energy consumption, and the benzene inlet needs to be heated by a heating furnace.

[0007] There are two main processes for preparing ethylbenzene by catalytic dry gas liquid phase. One is the bubbling bed process, in which the catalyst is completely immersed in benzene, and the catalytic dry gas passes through the catalyst completely immersed in benzene in the form of bubbles, and reacts with benzene to produce ethylbenzene, and then the ethylbenzene product is obtained through subsequent separation. The other is the catalytic distillation process, in which the catalytic dry gas and fresh benzene enter from the bottom and top of the tower respectively, and benzene absorbs the catalytic dry gas while undergoing alkylation reaction in the catalytic distillation tower. The catalytic distillation tower usually adopts a plate tower or a packed tower, and the catalyst is distributed in the tower. The tail gas after the reaction (mainly hydrogen, methane, ethane, nitrogen and other components) is discharged from the top of the tower, and a mixture of ethylbenzene and benzene is obtained at the bottom of the tower, and then enters the subsequent device for separation to obtain the ethylbenzene product. The bubbling bed process completely immerses the catalyst, which can protect the catalyst to a certain extent, but due to the low absorption efficiency of the bubbling bed, the process has the disadvantages of low conversion rate, poor selectivity and large catalyst dosage. The catalytic distillation process has high absorption efficiency, high conversion rate, good selectivity and low catalyst usage, but the process cannot guarantee that the catalyst is completely free from contact with the gas phase and the life of the catalyst cannot be guaranteed.

[0008] CN102267859B proposes a method for producing ethylbenzene from ethylene, which is a liquid-phase method for producing ethylbenzene. In this method, an alkylation reactor is provided with N absorption sections and N reaction sections. A mixture containing ethylene and an inert component is divided into N parts and enters the bottom of the Nth absorption section of the alkylation reactor respectively, contacts with an absorbent from an absorbent inlet at the top of the alkylation reactor in the absorption section and dissolves in the absorbent, and flows downward into the reaction section to react and generate ethylbenzene and polyethylbenzenes. In the alkylation reactor, the absorbent passes through each absorption section and reaction section in sequence. The present invention can significantly improve the conversion rate and recovery rate of ethylene, and can effectively ensure that the reaction is carried out under liquid phase conditions, avoiding direct contact between gas-phase ethylene and the catalyst, but the absorbent has a long residence time in the catalyst bed, more side reactions, and a complex reactor structure and is difficult to manufacture.

[0009] In summary, the current dry gas to ethylbenzene process used in industrial refineries is mainly based on the gas phase method, which has problems such as low ethylene recovery rate, many by-products, and high energy consumption. Summary of the invention

[0010] To solve the above problems, the present invention provides a device for preparing ethylbenzene by a liquid phase process containing ethylene dry gas, so as to solve the technical problems existing in the existing dry gas process for preparing ethylbenzene, such as high energy consumption, low ethylene recovery rate, many by-products, and short catalyst operation cycle.

[0011] To achieve the above object, the technical solution adopted by the present invention is:

[0012] An ethylene-containing dry gas liquid phase method for preparing ethylbenzene comprises an ethylene-containing dry gas pretreatment unit, a propylene removal unit, a fresh benzene treatment unit, an alkylation reaction unit and a product separation unit, wherein each unit is connected via a pipeline, and is characterized in that: the ethylene-containing dry gas pretreatment unit is a water washing tower and a dryer in sequence; the propylene removal unit is an absorption tower, an ethylene desorption tower and a propylene desorption tower in sequence, and the three towers are connected via a pipeline; the fresh benzene treatment unit is a fresh benzene pretreatment unit and a guard bed reactor in sequence; the alkylation reaction unit comprises an ethylene absorption tower, a mixer, a raw material heat exchanger, an alkylation reactor, a steam generator, a product flash tank and a deethanizer, which are connected to each other via a pipeline;

[0013] The top of the dryer is connected to the bottom of the absorption tower; the top of the absorption tower is connected to the bottom of the ethylene absorption tower, and the top of the ethylene desorption tower is respectively connected to the mixer of the alkylation reaction unit and the protection reactor of the fresh benzene processing unit; the protection reactor is connected to the mixer of the alkylation reaction unit.

[0014] The invention discloses a device for preparing ethylbenzene by a dry gas-liquid phase method containing ethylene, which is further characterized in that the fresh benzene pretreatment device is connected with a guard bed reactor, and the guard bed reactor is connected with a mixer.

[0015] The present invention provides a device for preparing ethylbenzene by a dry gas-liquid phase method containing ethylene, which is further characterized in that: the bottom of the absorption tower is connected to the middle part of the ethylene desorption tower through the absorption tower bottom pump, the bottom of the ethylene desorption tower is connected to the middle and upper part of the propylene desorption tower; the top of the ethylene desorption tower is respectively connected to the mixer of the alkylation reaction unit and the protection reactor of the fresh benzene processing unit; the bottom of the propylene desorption tower is respectively connected to the top of the absorption tower and the top of the ethylene desorption tower.

[0016] The present invention provides a device for preparing ethylbenzene by a liquid phase process containing ethylene dry gas, which is further characterized in that: the bottom of the ethylene absorption tower in the alkylation reaction unit is connected to a mixer through a booster pump, and the mixer is connected to the alkylation reactor through a raw material buffer tank and a reactor feed pump; the material at the bottom of the alkylation reactor enters a product flash tank through a hydraulic turbine, the top of the flash tank is connected to the lower part of a deethanizer, and the bottom of the flash tank is respectively connected to the ethylene absorption tower and a product separation unit; the bottom of the deethanizer is connected to a raw material heat exchanger before the alkylation reactor.

[0017] The present invention provides a device for preparing ethylbenzene by a liquid phase process containing ethylene dry gas, which is further characterized in that: the bottom of the raw material buffer tank is connected to the alkylation reactor through the reactor feed pump pressurization, the raw material first heat exchanger, and the second heat exchanger; the bottom of the alkylation reactor is connected to the reaction product flash tank through the raw material second heat exchanger, the steam generator, and the hydraulic turbine.

[0018] The present invention provides a device for preparing ethylbenzene by a dry gas-liquid phase method containing ethylene, which is further characterized in that: the bottom of a product flash tank is connected to a first heat exchanger for raw materials and is divided into two paths, one of which is connected to a product separation unit; the other is connected to a circulating absorbent cooler through a circulating absorbent booster pump; the outlet of the circulating absorbent cooler is connected to an ethylene absorption tower or is divided into two paths and respectively connected to the ethylene absorption tower and a mixer.

[0019] The present invention provides a device for preparing ethylbenzene by a dry gas-liquid phase method containing ethylene, which is further characterized in that: the top of the ethylene absorption tower is connected to a 1# re-contact system, which is connected to a product separation unit; the top of the deethanizer is connected to a 2# re-contact system, which is connected to a product separation unit; the bottom of the deethanizer is connected to a second raw material heat exchanger and an alkylation reactor in sequence.

[0020] The present invention discloses a device for preparing ethylbenzene by a liquid phase method containing ethylene dry gas, which is further characterized in that: the deethanizer has 5 to 50 theoretical plates, the tower top pressure is 0.3 to 1.5 MPag, the tower top temperature is 100 to 180°C, and a hot water heat exchanger and a condenser are arranged at the tower top of the deethanizer.

[0021] The present invention provides a device for preparing ethylbenzene by a dry gas-liquid phase process containing ethylene, which is further characterized in that the outlet pressure of the hydraulic turbine is 0.3MPag to 1.5MPag, preferably 0.40 to 0.65MPag, which is used to drive a reactor feed pump.

[0022] The present invention provides a device for preparing ethylbenzene by a dry gas-liquid phase process containing ethylene, which is further characterized in that: the alkylation reactor is a liquid phase alkylation reactor, one or N of which are connected in parallel, and when N are connected in parallel, the feed of the alkylation reactor is divided into N streams of liquid phase materials which enter N reactors (or reaction beds) respectively, and N is preferably equally divided, 1≤N≤10, and the number of N is determined according to the engineering design scale of the device for preparing ethylbenzene by a dry gas-liquid phase process containing ethylene.

[0023] The present invention is a device for preparing ethylbenzene by a dry gas liquid phase process containing ethylene, which is further characterized in that: the inlet temperature range of the liquid phase alkylation reactor is 150-280°C, the pressure range is 3-5MPag, and the temperature rise range of the alkylation reactor is 5-60°C. Preferably, the inlet temperature of the alkylation reactor is 200-210°C, the pressure is 4.0-4.5MPag, and the temperature rise of the alkylation reactor is 10-25°C. The total benzene / total ethylene molar ratio of the alkylation reaction unit feed is 1.2-4.

[0024] The present invention provides an ethylene-containing dry gas liquid phase method for preparing ethylbenzene, which is further characterized in that it also includes a product separation unit, which includes a benzene recovery tower, an ethylbenzene rectification tower, a propylbenzene tower, a polyethylbenzene tower, a non-aromatic tower and an alkylation translocation reactor, etc., which are connected to each other through pipelines. The reaction product from the alkylation reaction unit is sent to the product separation unit to separate ethylbenzene products, polyethylbenzenes and circulating benzene, etc. The circulating benzene of the product separation unit is returned to the mixer of the alkylation reaction unit, and can also be returned to the guard bed reactor of the fresh benzene processing unit.

[0025] The present invention discloses a device for preparing ethylbenzene by liquid phase method using ethylene-containing dry gas, which is further characterized in that: the ethylene volume content of the ethylene-containing dry gas is 5% to 95%, and the ethylene-containing dry gas also contains trace MDEA impurities and one or more of components such as H2, N2, O2, CO, CO2, CH4, C2H4, C2H6, C3H6, C3H8, C4+, etc.; the entrained trace impurities are removed by water washing, and the dry gas needs to be dehydrated by a dryer before propylene removal, and the water content in the dry gas after drying is controlled to be ≯300ppm, preferably the water content in the dry gas is controlled to be ≯100ppm.

[0026] The present invention discloses a device for preparing ethylbenzene from ethylene-containing dry gas by liquid phase method. The absorbent is in countercurrent contact with the ethylene-containing dry gas in the absorption tower to absorb propylene and heavy components in the ethylene-containing dry gas, and also absorbs a small amount of ethylene and other light components. The absorbent is one or more of benzene, ethylbenzene, methylethylbenzene and diethylbenzene. The absorption tower has 10 to 50 theoretical plates, the tower top pressure is 0.6 to 4.5 MPag, preferably 0.8 to 1.5 MPag, and the absorption temperature is 5 to 60°C, preferably 15 to 20°C.

[0027] The invention discloses a device for preparing ethylbenzene by liquid phase method containing ethylene dry gas, which is further characterized in that the propylene content in the dry gas at the top of the absorption tower and the ethylene-rich gas at the top of the ethylene desorption tower is controlled to be ≯300ppm by adjusting the absorption dosage at the top of the absorption tower and the ethylene desorption tower.

[0028] The present invention provides an ethylene-containing dry gas liquid phase method for preparing ethylbenzene, which is further characterized in that the ethylene desorption tower has 10 to 50 theoretical plates, the tower top pressure is 0.6 to 4.5 MPag, preferably 0.8 to 1.5 MPag, and the desorption temperature is 150 to 280°C, preferably 160 to 230°C.

[0029] The present invention provides an ethylene-containing dry gas-liquid phase method for preparing ethylbenzene, which is further characterized in that: the ethylene absorption tower is a packed tower or a plate tower, the tower top pressure is 0.5-4.5 MPag, preferably 0.7-1.5 MPag, and the absorption temperature is 5-120° C., preferably 10-40° C. The circulating absorption liquid of the ethylene absorption tower is the alkylation reaction product.

[0030] The present invention provides a device for preparing ethylbenzene by a liquid phase method containing ethylene dry gas, which is further characterized in that the ethane-rich gas at the top of the deethanizer tower can be directly used as a raw material for an ethylene cracking device after a small amount of benzene carried by the gas is recovered by a re-contact system.

[0031] The present invention discloses a device for preparing ethylbenzene by a liquid phase method containing ethylene dry gas, which is further characterized in that: the deethanizer has 5 to 50 theoretical plates, the tower top pressure is 0.3 to 1.5 MPag, the tower top temperature is 100 to 180°C, and a hot water heat exchanger and a condenser are arranged at the tower top of the deethanizer.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] 1. The present invention sets a dryer after washing the raw material ethylene-containing dry gas with water to remove moisture from the dry gas, and controls the water content in the dry gas to be ≯300ppm, especially to control the water content in the dry gas to be ≯100ppm, so as to ensure that the active center of the catalyst is not affected by the moisture in the dry gas, thereby maximizing the activity and life of the catalyst.

[0034] 2. The present invention dissolves all the ethylene in the dry gas by first absorbing and then pressurizing the mixed dissolution in the liquid phase. After dissolution, the dry gas containing ethylene is pressurized to the pressure required for the reaction by a pump. The ethylene-containing dry gas after propylene removal enters the ethylene absorption tower without using a gas compressor, which greatly reduces the investment, land occupation, energy consumption and operating costs of the device and improves the safe operation reliability of the device.

[0035] 3. The present invention adopts liquid phase alkylation reaction to produce ethylbenzene, avoiding direct contact between gas phase ethylene and catalyst, delaying coking and deactivation of catalyst. The liquid phase alkylation reaction temperature is controlled at 200-210°C, reducing the occurrence of side reactions, especially the formation of xylene, reducing the content of xylene in the ethylbenzene product, improving the conversion rate of ethylene, and correspondingly increasing the yield of ethylbenzene.

[0036] 4. The alkylation reactor of the present invention is one or N reactors connected in parallel. When N reactors are connected in parallel, the feed of the alkylation reactor needs to be divided into N liquid phase materials and enter N reactors or reaction beds respectively, 1≤N≤10, N is determined by the scale of ethylbenzene, the total benzene / total ethylene molar ratio in the feed of the alkylation reaction unit is 1.2-4, the benzene-ethylene ratio in the feed of each reactor is greater than 15, the ethylene conversion rate and selectivity are high, and the temperature rise of the reactor or reaction bed is controllable.

[0037] 5. In the reaction part of the present invention, the heat of the alkylation reaction is fully recovered and utilized, and the reaction part basically does not require external heat. Compared with the gas-phase ethylbenzene production process containing ethylene dry gas, the circulating benzene heating furnace and other facilities are eliminated, which greatly reduces the energy consumption of the device.

[0038] 6. The present invention provides a flash tank in the alkylation reaction unit. After the alkylation product is depressurized by the hydraulic turbine, most of the non-condensable gases (CH4, C2H6 and trace amounts of H2, N2, CO2, etc.) dissolved in the reaction materials are flashed out in the flash tank, thereby increasing the absorption capacity of the circulating absorption liquid for ethylene and reducing the amount of the circulating absorption liquid.

[0039] 7. The present invention sets a deethanizer in the alkylation reaction unit to recover benzene, ethylbenzene, etc. entrained in the non-condensable gas of the flash tank and return them to the reaction feed to continue to participate in the reaction. The ethane-rich gas at the top of the deethanizer is recovered by the re-contact system to carry a small amount of benzene, which can be directly used as a raw material for the ethylene cracking unit, thereby improving the utilization rate of ethane in the dry gas.

[0040] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the scope of application of the present invention is not limited thereto. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of a process flow of a device for preparing ethylbenzene by a dry gas-liquid phase process containing ethylene according to the present invention;

[0042] Figure 2The present invention is a schematic diagram of a device flow chart of two parallel alkylation reactors for preparing ethylbenzene by a dry gas-liquid phase process containing ethylene;

[0043] Figure 3 The present invention is a schematic diagram of the process of preparing ethylbenzene by a dry gas-liquid phase process containing ethylene using three parallel alkylation reactors.

[0044] The reference numerals shown in the figures are: 1-water washing tower; 2-dryer; 3-absorption tower; 4-absorption tower bottom pump; 5-ethylene desorption tower; 6-propylene desorption tower; 7-fresh benzene pretreatment unit; 8-guard bed reactor; 9-ethylene absorption tower; 10-ethylene absorption tower bottom booster pump; 11-mixer; 12-raw material buffer tank; 13-reactor feed pump; 14-raw material first heat exchanger; 15-raw material second heat exchanger; 16-standby steam heater; 17-alkylation reactor; 18-steam generator ; 19-hydraulic turbine; 20-product flash tank; 21-circulating absorbent booster pump; 22-circulating absorbent cooler; 23-deethanizer; 24-product separation unit; 25-1# re-contact system; 26-lean circulating absorption liquid; 27-reaction product to subsequent product separation unit; 28-mixer to supplement absorption liquid; 29-2# re-contact system; Ⅰ-ethylene-containing dry gas pretreatment unit; Ⅱ-depropylene unit; Ⅲ-fresh benzene processing unit; Ⅳ-alkylation reaction unit; Ⅴ-product separation unit. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the accompanying drawings.

[0046] As attached Figure 1 As shown, the device for preparing ethylbenzene by liquid phase method of dry gas containing ethylene of the present invention comprises a dry gas pretreatment unit containing ethylene I, a propylene removal unit II, a fresh benzene treatment unit III, an alkylation reaction unit IV and a product separation unit V, and each unit is connected by a pipeline;

[0047] The ethylene-containing dry gas from the upstream first enters the ethylene-containing dry gas pretreatment unit I, and then passes through the water washing tower 1 and the dryer 2 of the ethylene-containing dry gas pretreatment unit I in sequence. The dried ethylene-containing dry gas enters the depropylene unit II through a pipeline;

[0048] The ethylene-containing dry gas passes through the absorption tower 3, the ethylene desorption tower 5 and the propylene desorption tower 6 in the propylene removal unit II in sequence, and the three towers are connected by pipelines; the ethylene-containing dry gas comes from the ethylene-containing dry gas pretreatment unit I and enters the lower part of the absorption tower 3. After absorption in the absorption tower 3, the liquid phase at the bottom of the absorption tower 3 is pressurized by the absorption tower bottom pump 4 and enters the ethylene desorption tower 5 through a pipeline, and the gas phase at the top of the absorption tower 3 enters the ethylene absorption tower 9 of the alkylation reaction unit IV through a pipeline; the gas phase at the top of the ethylene desorption tower 5 is respectively sent to the mixer 11 of the alkylation reaction unit IV and the guard bed reactor 8 of the fresh benzene treatment unit III, and the liquid phase at the bottom of the tower enters the propylene desorption tower 6 through a pipeline; the propylene-rich gas at the top of the propylene desorption tower 6 is sent out of the propylene desorption tower 6. The liquid phase at the bottom of the tower returns to the absorption tower 3 and the ethylene desorption tower 5 through a pipeline;

[0049] Fresh benzene from outside the boundary area passes through the fresh benzene pretreatment device 7 and the guard bed reactor 8 in the fresh benzene treatment unit III in sequence, and after being treated, enters the mixer 11 of the alkylation reaction unit IV through a pipeline;

[0050] The ethylene-containing dry gas from the top of the absorption tower 3 enters the lower part of the ethylene absorption tower 9 of the alkylation reaction unit IV. After absorption, the gas at the top of the ethylene absorption tower 9 is treated by the 1# re-contact system 25 and then sent out of the device. The rich circulating absorption liquid at the bottom of the ethylene absorption tower 9 is pressurized by the ethylene absorption tower bottom booster pump 10 and then passes through the mixer 11, the raw material buffer tank 12, the reactor feed pump 13, the raw material first heat exchanger 14, the raw material second heat exchanger 15, and the alkylation reactor 17 through the pipeline in sequence. The alkylation reaction product passes through the raw material second heat exchanger 15, the steam generator 18, the hydraulic turbine 19, the product flash reactor 17 in sequence. The top gas of the product flash tank 20 is connected to the deethanizer 23 through a pipeline, and the bottom liquid of the deethanizer 23 returns to the second heat exchanger 15 of the raw material. The top of the tower is treated by the 2# re-contact system 29 to obtain ethane-rich gas; the bottom liquid of the product flash tank 20 is divided into two streams, and the first stream of material 26 is pressurized by the circulating absorbent booster pump 21 and cooled by the circulating absorbent cooler 22. Most of it enters the upper part as the lean circulating absorption liquid of the ethylene absorption tower 9, and another small part enters the mixer as the supplementary absorption liquid 28 of the mixer. The second stream of material 27 is sent to the subsequent product separation unit 24 as the product.

[0051] The reaction products from the alkylation reaction unit IV are separated in the product separation unit 24 to obtain products such as ethylbenzene, polyethylbenzenes and a circulating pump.

[0052] With attached Figure 1 The difference is that in order to adapt to the larger scale ethylbenzene production unit, Figure 2 The implementation method is to add a parallel alkylation reactor 17 and corresponding supporting heat exchange, pressure reduction, flash evaporation and other systems to the alkylation reaction unit IV;

[0053] With attached Figure 1The difference is that in order to adapt to the larger scale ethylbenzene production unit, Figure 3 The implementation method adds two parallel alkylation reactors 17 and corresponding supporting heat exchange, pressure reduction, flash evaporation and other systems to the alkylation reaction unit IV; and because the raw benzene is sufficient to completely dissolve the ethylene-rich gas from the top of the ethylene desorption tower 5, the mixer 11 is no longer equipped with a mixer supplementary absorption liquid 28 pipeline.

[0054] [Example 1]

[0055] A 120,000 t / a catalytic dry gas-liquid phase ethylbenzene production unit uses Figure 1 process.

[0056] in:

[0057] The absorption tower has 15 theoretical plates, the absorption pressure is 0.9MPag, and the absorption temperature is 15℃;

[0058] The ethylene desorption tower has 15 theoretical plates, a desorption tower pressure of 1.2 MPag, and a tower top temperature of 29°C;

[0059] The bottom temperature is 187°C.

[0060] The ethylene absorption tower adopts a packed tower, with an absorption pressure of 0.85MPag and an absorption temperature of 15°C;

[0061] The total benzene / total ethylene molar ratio of the alkylation reaction unit feed is 3.2:1;

[0062] Alkylation reactor: One alkylation reactor is provided, the reaction temperature is 205°C, and the pressure is 4.3MPag;

[0063] Mixer supplementary absorption liquid flow rate: 20t / h;

[0064] The hydraulic turbine outlet pressure is 0.55MPag;

[0065] The deethanizer uses 8 theoretical plates, the top pressure is 0.52MPag, and the top temperature is 109℃.

[0066] The process conditions and raw material data are shown in Table 1.

[0067] Table 1 Composition of raw material containing ethylene dry gas

[0068] project Catalytic dry gas Fresh Benzene Pressure, MPag 1.0 0.5 Temperature, °C 35 40 Mass flow kg / h 18956 10330 <![CDATA[H2]]> 648 <![CDATA[N2]]> 4035 <![CDATA[O2]]> 200 <![CDATA[CO2]]> 1002 <![CDATA[CH4]]> 4190 <![CDATA[C2H4]]> 3929 <![CDATA[C2H6]]> 4176 <![CDATA[C3H6]]> 356 <![CDATA[C3H8]]> 93 BZ 10330 other 327

[0069] The products after separation in this example are shown in Table 2.

[0070] Table 2 Output and composition of main products

[0071] Propylene-rich gas Methane Hydrogen Ethane-rich gas Ethylbenzene Polyethylbenzene Non Fang Mass flow kg / h 1007 10847 2938 14469 451 432 <![CDATA[H2]]> 633 15 <![CDATA[N2]]> 3848 181 6 <![CDATA[O2]]> 176 24 <![CDATA[CO2]]> 550 410 42 <![CDATA[CH4]]> 3506 652 32 <![CDATA[C2H4]]> 14 6 <![CDATA[C2H6]]> 315 1920 1606 335 <![CDATA[C3H6]]> 354 <![CDATA[C3H8]]> 92 1 BZ 8 180 14 1.7 17 EB 20 28 14467 Multi-EB 7 8 0.3 451 other 250

[0072] According to calculations, in this embodiment, the ethylene conversion rate can reach more than 99.95%, and the ethylene recovery rate can reach more than 99.5%. Compared with the same scale gas phase process, the energy consumption of the device is reduced by about 25%.

[0073] [Example 2]

[0074] A 400,000 t / a catalytic dry gas-liquid phase ethylbenzene production unit uses Figure 3 process.

[0075] in:

[0076] The absorption tower has 20 theoretical plates, absorption pressure is 0.85MPag, and absorption temperature is 15℃;

[0077] The ethylene desorption tower has 20 theoretical plates, the desorption tower pressure is 1.2MPag, the tower top temperature is 28℃, and the tower bottom temperature is 191℃.

[0078] The ethylene absorption tower adopts a packed tower, with an absorption pressure of 0.82MPag and an absorption temperature of 40℃;

[0079] The total benzene / total ethylene molar ratio of the alkylation reaction unit feed is 2:1;

[0080] The alkylation reactor is equipped with three parallel feed reactors, with a reaction inlet temperature of 205°C and a pressure of 4.3MPag;

[0081] The hydraulic turbine outlet pressure is 0.55MPag;

[0082] The deethanizer uses 8 theoretical plates, the top pressure is 0.52MPag, and the top temperature is 129℃.

[0083] The process conditions and raw material data are shown in Table 3.

[0084] Table 3 Composition of raw material containing ethylene dry gas

[0085]

[0086]

[0087] The products after separation in this example are shown in Table 4.

[0088] Table 4 Output and composition of main products

[0089] Propylene-rich gas Methane Hydrogen Ethane-rich gas Ethylbenzene Polyethylbenzene Non Fang Mass flow kg / h 1228 13275 5329 51404 1476 860 <![CDATA[H2]]> 929 34 <![CDATA[N2]]> 3651 254 3 <![CDATA[O2]]> 168 31 1 CO 244 21 <![CDATA[CO2]]> 198 232 14 <![CDATA[CH4]]> 6154 1626 47 <![CDATA[C2H4]]> 31 34 <![CDATA[C2H6]]> 320 1671 3051 273 <![CDATA[C3H6]]> 773 <![CDATA[C3H8]]> 20 BZ 18 210 32 6 18 EB 15 44 51326 Multi-EB 72 1476 other 86 4 504

[0090] According to calculations, in this embodiment, the ethylene conversion rate can reach more than 99.95%, and the ethylene recovery rate can reach more than 99.5%. Compared with the gas phase process of the same scale, the energy consumption of the device is reduced by about 52%.

[0091] The above describes the implementation methods of the present patent in detail, but the present patent is not limited to the above implementation methods. Within the knowledge of ordinary technicians in this field, various changes can be made without departing from the purpose of the present patent, such as equally or unequally dividing N liquid-phase alkylation reaction feeds, using one or more ethylene absorption towers, and using parallel feeding or series-parallel combination feeding methods for N liquid-phase reactors, all of which are within the protection scope of the present patent.

Claims

1. A device for preparing ethylbenzene by liquid phase process of ethylene-containing dry gas, comprising an ethylene-containing dry gas pretreatment unit, a propylene removal unit, a fresh benzene treatment unit, an alkylation reaction unit and a product separation unit, wherein the units are connected by pipelines, and characterized in that: The ethylene-containing dry gas pretreatment unit is sequentially composed of a water washing tower and a dryer; the propylene removal unit is sequentially composed of an absorption tower, an ethylene desorption tower and a propylene desorption tower, and the three towers are connected by pipelines; the fresh benzene processing unit is sequentially composed of a fresh benzene pretreatment unit and a guard bed reactor; the alkylation reaction unit includes an ethylene absorption tower, a mixer, a raw material heat exchanger, an alkylation reactor, a steam generator, a product flash tank and a deethanizer, which are connected to each other by pipelines; the top of the dryer is connected to the bottom of the absorption tower; the top of the absorption tower is connected to the bottom of the ethylene absorption tower, and the top of the ethylene desorption tower is respectively connected to the mixer of the alkylation reaction unit and the guard reactor of the fresh benzene processing unit; the guard reactor is connected to the mixer of the alkylation reaction unit; The bottom of the ethylene absorption tower in the alkylation reaction unit is connected to the mixer through a booster pump, and the mixer is connected to the alkylation reactor through a raw material buffer tank and a reactor feed pump; the material at the bottom of the alkylation reactor enters the product flash tank through a hydraulic turbine, the top of the flash tank is connected to the lower part of the deethanizer, and the bottom of the flash tank is respectively connected to the ethylene absorption tower and the product separation unit; the bottom of the deethanizer is connected to the raw material heat exchanger before the alkylation reactor; The bottom of the raw material buffer tank is connected to the alkylation reactor via the reactor feed pump, the first raw material heat exchanger, and the second raw material heat exchanger; the bottom of the alkylation reactor is connected to the reaction product flash tank via the second raw material heat exchanger, the steam generator, and the hydraulic turbine; The bottom of the product flash tank is connected to the first raw material heat exchanger and is divided into two paths, one of which is connected to the product separation unit; the other is connected to the circulating absorbent cooler through the circulating absorbent booster pump; the outlet of the circulating absorbent cooler is connected to the ethylene absorber or is divided into two paths and respectively connected to the ethylene absorber and the mixer.

2. The device for preparing ethylbenzene by dry gas-liquid phase process containing ethylene according to claim 1, characterized in that: The bottom of the absorption tower is connected to the middle of the ethylene desorption tower through the absorption tower bottom pump, and the bottom of the ethylene desorption tower is connected to the middle and upper part of the propylene desorption tower; the top of the ethylene desorption tower is respectively connected to the mixer of the alkylation reaction unit and the protection reactor of the fresh benzene processing unit; the bottom of the propylene desorption tower is respectively connected to the top of the absorption tower and the top of the ethylene desorption tower.

3. The device for preparing ethylbenzene by dry gas-liquid phase process containing ethylene according to claim 1, characterized in that: The fresh benzene pre-treatment device is connected with the guard bed reactor, and the guard bed reactor is connected with the mixer.

4. The device for preparing ethylbenzene by dry gas-liquid phase process containing ethylene according to claim 1, characterized in that: The bottom of the absorption tower is connected to the middle of the ethylene desorption tower through the absorption tower bottom pump, and the bottom of the ethylene desorption tower is connected to the middle of the propylene desorption tower; the top of the ethylene desorption tower is respectively connected to the mixer of the alkylation reaction unit and the protection reactor of the fresh benzene processing unit; the bottom of the propylene desorption tower is respectively connected to the top of the absorption tower and the top of the ethylene desorption tower.

5. The device for preparing ethylbenzene by dry gas-liquid phase process containing ethylene according to claim 1, characterized in that: The top of the ethylene absorption tower is connected to the 1# re-contact system, and the 1# re-contact system is connected to the product separation unit; the top of the deethanizer is connected to the 2# re-contact system, and the 2# re-contact system is connected to the product separation unit; the bottom of the deethanizer is connected to the second raw material heat exchanger and the alkylation reactor in sequence.

6. The device for preparing ethylbenzene by dry gas-liquid phase process containing ethylene according to claim 1, characterized in that: The deethanizer has 5 to 50 theoretical plates, a top pressure of 0.3 to 1.5 MPag, a top temperature of 100 to 180° C. A hot water heat exchanger and a condenser are provided at the top of the deethanizer.

7. The device for preparing ethylbenzene by dry gas-liquid phase process containing ethylene according to claim 1, characterized in that: The alkylation reactor is a liquid phase alkylation reactor, one or N parallel connected, when N parallel connected, the feed of the alkylation reactor is divided into N streams of liquid phase materials respectively entering N reactors or reaction beds, 1≤N≤10.

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