A benzene and styrene organic waste gas recovery and purification system and treatment method

Abstract

The present invention relates to a benzene and styrene organic waste gas recovery and purification treatment system and treatment method, the recovery and purification treatment system comprises a benzene waste gas absorption system, a styrene waste gas absorption system and an organic waste gas absorption system, the benzene waste gas absorption system and the styrene waste gas absorption system are connected in parallel, and are respectively connected to the organic waste gas absorption system, the benzene waste gas absorption system and the styrene waste gas absorption system both comprise a liquid ring compressor, a gas-liquid separator, an absorption tower, a condenser, an ethylbenzene lean liquid device, a circulating pump, and a rich liquid distillation device, and the organic waste gas absorption system comprises three adsorption units connected in parallel, each of which comprises an adsorption tower, a circulating water pump, a circulating water heater, a circulating water cooler, a regeneration vacuum pump, and a regeneration condenser. The recovery and purification treatment system of the present invention has low energy consumption, good purification effect, completely avoids the generation of hazardous chemical waste, and meets environmental protection requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of organic waste gas recovery and purification, and specifically relates to a benzene and styrene organic waste gas recovery and purification system and a treatment method. Background Art

[0002] Benzene and styrene volatile gases are generated in polystyrene production equipment, as well as in benzene and styrene storage, ship loading and unloading, and car platform loading and unloading. Traditionally, benzene and styrene volatile organic compounds are mainly recovered and purified through the following methods or devices: direct condensation recovery by deep cooling, adsorption recovery by activated carbon tower, thermal storage catalytic combustion, water spray absorption, photocatalysis, photocatalysis plus activated carbon, adsorption recovery by activated carbon tower plus vacuum desorption and absorption, etc.

[0003] However, in the traditional cryogenic method, the recyclables are mixed together and require multi-stage distillation recovery, which consumes a lot of energy for cryogenic treatment. The traditional activated carbon tower adsorption method cannot achieve activated carbon regeneration, and it deactivates quickly in the recovery of polystyrene waste gas, generating a large amount of activated carbon hazardous chemical waste. Traditional heat storage catalytic combustion, water spray absorption, photocatalysis, and photocatalysis plus activated carbon treatment of exhaust gas cannot meet emission standards. Activated carbon tower adsorption plus vacuum desorption and absorption improves the use time of activated carbon, but the activated carbon will still lose activity in a relatively short time. The desorbed gas is discharged through absorption again, resulting in a small amount of volatile matter being discharged, and the purified exhaust gas cannot meet emission standards.

[0004] Chinese patent CN109304084A discloses a method for recovering organic waste gas containing styrene in tank area and loading materials, firstly, the organic waste gas is absorbed by an absorption tower, then the absorbed organic waste gas enters the adsorption system for adsorption, and finally the adsorbed organic waste gas enters the catalytic oxidation system for treatment and then reaches the emission standard. The patent adopts the process route of "absorption + adsorption + catalytic oxidation" to treat the organic waste gas, but the organic waste gas is absorbed at room temperature and pressure, and the organic waste gas such as benzene, toluene, styrene, etc. is mixed and treated together, and its absorption effect is poor; at the same time, the patent uses a vacuum pump to regenerate the adsorption system at room temperature, and its desorption regeneration effect is poor. Summary of the invention

[0005] The purpose of the present invention is to provide a benzene and styrene organic waste gas recovery and purification system and treatment method, which has low energy consumption, good purification effect, completely avoids the generation of hazardous chemical waste, and meets environmental protection requirements.

[0006] The technical solution adopted by the present invention to solve the above-mentioned problem is: a benzene and styrene organic waste gas recovery and purification treatment system, the recovery and purification treatment system includes a benzene waste gas absorption system, a styrene waste gas absorption system and an organic waste gas adsorption system, the benzene waste gas absorption system and the styrene waste gas absorption system are connected in parallel and are respectively connected to the organic waste gas adsorption system, and the structural devices and connection methods contained in the benzene waste gas absorption system and the styrene waste gas absorption system are the same.

[0007] The benzene waste gas absorption system includes a first liquid ring compressor, the inlet of the first liquid ring compressor is connected to the benzene waste gas, the outlet of the first liquid ring compressor is connected to the first gas-liquid separator and the first cooler in sequence to enter the first absorption tower, the upper inlet of the first absorption tower is connected to the first ethylbenzene lean liquid device via the first condenser, the bottom outlet of the first absorption tower is connected to the side inlet of the first gas-liquid separator, the bottom outlet of the first gas-liquid separator is connected to the first rich liquid distillation device via the first circulation pump, and the top outlet of the first absorption tower is connected to the organic waste gas system.

[0008] The styrene waste gas absorption system includes a second liquid ring compressor, the inlet of the second liquid ring compressor is connected to the styrene waste gas, the outlet of the second liquid ring compressor is connected to the second gas-liquid separator and the second cooler in sequence to enter the second absorption tower, the upper inlet of the second absorption tower is connected to the second ethylbenzene lean liquid device via the second condenser, the bottom outlet of the second absorption tower is connected to the side inlet of the second gas-liquid separator, the bottom outlet of the second gas-liquid separator is connected to the second rich liquid distillation device via the second circulation pump, and the top outlet of the second absorption tower is connected to the organic waste gas system.

[0009] The organic waste gas system includes a first adsorption unit, a second adsorption unit, and a third adsorption unit connected in parallel. The first adsorption unit, the second adsorption unit, and the third adsorption unit are respectively connected to the first liquid ring compressor and the second liquid ring compressor via a regeneration vacuum pump and a regeneration condenser. The first adsorption unit includes a first adsorption tower, a first circulating water pump, a first circulating water heater, and a first circulating water cooler. The bottom inlet of the first adsorption tower is respectively connected to the top outlet of the first absorption tower of the benzene waste gas absorption system and the top outlet of the second absorption tower of the styrene waste gas absorption system. The first adsorption tower and the first circulating water pump, the first circulating water heater, and the first circulating water cooler form a circulation system. The top of the first adsorption tower is provided with a waste gas outlet that meets the emission standards.

[0010] The second adsorption unit and the third adsorption unit have the same structural devices and connection methods as the first adsorption unit. The second adsorption unit includes a second adsorption tower, a second circulating water pump, a second circulating water heater, and a second circulating water cooler. The third adsorption unit includes a third adsorption tower, a third circulating water pump, a third circulating water heater, and a third circulating water cooler.

[0011] Preferably, the adsorbent of the first absorption tower, the second adsorption tower and the third adsorption tower is a silica gel activated carbon mixture, wherein the mass ratio of silica gel to activated carbon is 5:1.

[0012] Preferably, the regenerative vacuum pump is a dry screw vacuum pump.

[0013] The regeneration condenser is also connected to a residual liquid recovery device.

[0014] Another object of the present invention is to provide a method for recovering and purifying benzene and styrene organic waste gas, comprising the following steps:

[0015] (1) Benzene waste gas and styrene waste gas enter the benzene waste gas absorption system and styrene waste gas absorption system respectively.

[0016] (2) After the benzene waste gas is pressurized by the first liquid ring compressor, it is cooled by the first gas-liquid separator and the first cooler and then enters the first absorption tower for absorption. The ethylbenzene lean liquid in the first ethylbenzene lean liquid device is cooled by the first condenser and enters the first absorption tower as an absorbent for spraying. After the absorption is completed, the liquid enters the first gas-liquid separator. Part of the liquid enters the first liquid ring compressor for circulation as liquid ring compressor liquid, and part of the liquid enters the first rich liquid distillation device through the first circulation pump for distillation recovery. After the absorption is completed, the gas enters the organic waste gas adsorption system from the top of the first absorption tower.

[0017] (3) After the styrene waste gas is pressurized by the second liquid ring compressor, it is cooled by the second gas-liquid separator and the second cooler and then enters the second absorption tower for absorption. The ethylbenzene lean liquid in the second ethylbenzene lean liquid device is cooled by the second condenser and enters the second absorption tower as an absorbent for spraying. After the absorption is completed, the liquid enters the second gas-liquid separator. Part of the liquid enters the second liquid ring compressor for circulation as liquid ring compressor liquid, and part of the liquid enters the second rich liquid distillation device through the second circulation pump for distillation recovery. After the absorption is completed, the gas enters the organic waste gas adsorption system from the top of the second absorption tower.

[0018] (4) The benzene waste gas and styrene waste gas that have passed through the benzene waste gas absorption system and the styrene waste gas absorption system in steps (2) and (3) respectively enter the first adsorption unit in the organic waste gas adsorption system in an adsorption state. The first adsorption tower uses the first circulating water pump to pressurize and the first circulating water cooler to cool the benzene and styrene waste gases to perform low-temperature deep adsorption. The tail gas is discharged from the top of the first adsorption tower. When the first absorption tower in the first adsorption and desorption unit is saturated with adsorption, the benzene waste gas and styrene waste gas enter the second adsorption unit. After the first adsorption unit is saturated with adsorption, it is pressurized by the first circulating water pump and heated by the first circulating water heater to perform temperature-raising desorption regeneration. At this time, the third adsorption tower in the third adsorption unit in a standby state uses the third circulating water pump to pressurize and the third circulating water cooler to cool to maintain low-temperature cooling.

[0019] (5) The benzene waste gas after desorption by the first desorption unit is pressurized by the regeneration vacuum pump and condensed by the regeneration condenser, and then enters the first liquid ring compressor for absorption and adsorption again. The styrene waste gas after desorption by the first desorption unit is pressurized by the regeneration vacuum pump and condensed by the regeneration condenser, and then enters the second liquid ring compressor for absorption and adsorption again.

[0020] Preferably, in step (3), the first adsorption unit, the second adsorption unit, and the third adsorption unit are alternately subjected to adsorption, standby, and desorption regeneration.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] (1) After being pressurized by a liquid ring compressor, benzene and styrene organic waste gas is cooled by a gas-liquid separator and a cooler and then enters an absorption tower for absorption. Compared with absorption at normal temperature and pressure, the absorption effect of pressurized and cooled organic waste gas is better.

[0023] (2) The present invention uses a liquid ring compressor to pressurize benzene and styrene gases to avoid sparks when the benzene and styrene waste gases contain oxygen. At the same time, ethylbenzene, a similar substance, is used in the liquid ring compressor to form a vacuum liquid ring. The liquid ring compressor is under negative pressure at the inlet, which increases the absorption of organic waste gas and has a large air intake volume.

[0024] (3) Benzene waste gas and styrene waste gas enter the benzene waste gas absorption system and styrene waste gas absorption system respectively. The two sets of absorption devices absorb separately, and benzene and styrene can be recovered separately, which has certain economic benefits.

[0025] (4) After the absorption is completed, part of the liquid enters the liquid ring compressor for circulation as liquid ring compressor liquid, and part enters the rich liquid distillation device for distillation recovery, which has certain economic benefits.

[0026] (5) The adsorption tower of the present invention, the circulating water pump, the circulating water heater, and the circulating water cooler form a circulation system, which realizes linear heating and cooling inside the adsorption tower through the circulating water, thereby avoiding the alternating stress caused by the sudden cooling and heating of the adsorption tower, effectively protecting the adsorption column in the adsorption tower and extending its service life.

[0027] (6) The present invention uses a circulating water pump and a circulating water cooler to perform low-temperature adsorption, which can greatly improve the adsorption efficiency; the present invention uses a circulating water pump, a circulating water heater, and a regeneration vacuum pump to perform vacuum heating desorption regeneration, which can completely realize the regeneration of the adsorbent.

[0028] (7) The three adsorption units in the organic waste gas adsorption system of the present invention alternately adsorb, desorb, regenerate and standby, thereby realizing continuous operation, saving energy and reducing consumption, and reducing processing costs, which has certain economic benefits; at the same time, the desorbed gas returns to the liquid ring compressor for re-absorption and adsorption, realizing a closed cycle, avoiding the generation of hazardous chemical waste, and meeting environmental protection requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a process flow chart for the recovery and purification of benzene and styrene organic waste gas.

[0030] Among them: 1 is a benzene waste gas absorption system, 1.1 is a liquid ring compressor, 1.2 is benzene waste gas, 1.3 is a first gas-liquid separator, 1.4 is a first cooler, 1.5 is a first absorption tower, 1.6 is a first condenser, 1.7 is a first ethylbenzene lean liquid device, 1.8 is a first circulation pump, and 1.9 is a first rich liquid distillation device.

[0031] 2 is a styrene waste gas absorption system, 2.1 is a second liquid ring compressor, 2.2 is styrene waste gas, 2.3 is a second gas-liquid separator, 2.4 is a second cooler, 2.5 is a second absorption tower, 2.6 is a second condenser, 2.7 is a second ethylbenzene lean liquid device, 2.8 is a second circulation pump, and 2.9 is a second rich liquid distillation device.

[0032] 3 is an organic waste gas adsorption system, 3.1 is a first adsorption unit, 3.2 is a second adsorption unit, 3.3 is a third adsorption unit, 3.4 is a regeneration vacuum pump, 3.5 is a regeneration condenser, 3.6 is a residual liquid recovery device, 3.1.1 is a first absorption tower, 3.1.2 is a first circulating water pump, 3.1.3 is a first circulating water heater, 3.1.4 is a first circulating water cooler, 3.2.1 is a second absorption tower, 3.2.2 is a second circulating water pump, 3.2.3 is a second circulating water heater, 3.2.4 is a second circulating water cooler, 3.3.1 is a third absorption tower, 3.3.2 is a third circulating water pump, 3.3.3 is a third circulating water heater, and 3.3.4 is a third circulating water cooler. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below with reference to the accompanying drawings. Example

[0034] like Figure 1 As shown, this is the process flow chart for the recovery and purification of benzene and styrene organic waste gas in this embodiment.

[0035] A benzene and styrene organic waste gas recovery and purification treatment system, the recovery and purification treatment system comprises a benzene waste gas absorption system 1, a styrene waste gas absorption system 2 and an organic waste gas adsorption system 3, the benzene waste gas absorption system 1 and the styrene waste gas absorption system 2 are connected in parallel and are respectively connected to the organic waste gas adsorption system 3.

[0036] The benzene waste gas absorption system 1 includes a first liquid ring compressor 1.1, the inlet of the first liquid ring compressor 1.1 is connected to the benzene waste gas 1.2, the outlet of the first liquid ring compressor 1.1 is connected to the first gas-liquid separator 1.3 and the first cooler 1.4 in sequence to enter the first absorption tower 1.5, the upper inlet of the first absorption tower 1.5 is connected to the first ethylbenzene lean liquid device 1.7 via the first condenser 1.6, the bottom outlet of the first absorption tower 1.5 is connected to the side inlet of the first gas-liquid separator 1.3, the bottom outlet of the first gas-liquid separator 1.3 is connected to the first rich liquid distillation device 1.9 via the first circulation pump 1.8, and the top outlet of the first absorption tower 1.5 is connected to the organic waste gas system 3.

[0037] The styrene waste gas absorption system 2 includes a second liquid ring compressor 2.1, the inlet of the second liquid ring compressor 2.1 is connected to the styrene waste gas 2.2, the outlet of the second liquid ring compressor 2.1 is connected to the second gas-liquid separator 2.3 and the second cooler 2.4 in sequence to enter the second absorption tower 2.5, the upper inlet of the second absorption tower 2.5 is connected to the second ethylbenzene lean liquid device 2.7 via the second condenser 2.6, the bottom outlet of the second absorption tower 2.5 is connected to the side inlet of the second gas-liquid separator 2.3, the bottom outlet of the second gas-liquid separator 2.3 is connected to the first rich liquid distillation device 2.9 via the second circulation pump 2.8, and the top outlet of the second absorption tower 2.5 is connected to the organic waste gas system 3.

[0038] The organic waste gas system 3 includes a first adsorption unit 3.1, a second adsorption unit 3.2, and a third adsorption unit 3.3 connected in parallel. The first adsorption unit 3.1, the second adsorption unit 3.2, and the third adsorption unit 3.3 are respectively connected to the first liquid ring compressor 1.1 and the second liquid ring compressor 2.1 through a regeneration vacuum pump 3.4 and a regeneration condenser 3.5. The first adsorption unit 3.1 includes a first adsorption tower 3.1.1, a first circulating water pump 3.1.2, a first circulating water heater 3.1.3, and a first circulating water cooler 3.1.4. The bottom inlet of the first adsorption tower 3.1.1 is respectively connected to the top outlet of the first absorption tower 1.5 of the benzene waste gas absorption system 1 and the top outlet of the second absorption tower 2.5 of the styrene waste gas absorption system 2. The first adsorption tower 3.1.1 and the first circulating water pump 3.1.2, the first circulating water heater 3.1.3, and the first circulating water cooler 3.1.4 form a circulation system. The top of the adsorption tower 3.1.1 is provided with a waste gas outlet that meets the emission standards.

[0039] The second adsorption unit 3.2 and the third adsorption unit 3.3 have the same structural devices and connection methods as the first adsorption unit 3.1. The second adsorption unit 3.2 includes a second adsorption tower 3.2.1, a second circulating water pump 3.2.2, a second circulating water heater 3.2.3, and a second circulating water cooler 3.2.4. The third adsorption unit 3.3 includes a third adsorption tower 3.3.1, a third circulating water pump 3.3.2, a third circulating water heater 3.3.3, and a third circulating water cooler 3.3.4.

[0040] The adsorbent of the first absorption tower 3.1.1, the second adsorption tower 3.2.1 and the third adsorption tower 3.3.1 is a silica gel activated carbon mixture, wherein the ratio of silica gel to activated carbon is 5:1.

[0041] The regeneration vacuum pump 3.4 is a dry screw vacuum pump.

[0042] The regeneration condenser 3.5 is also connected to a residual liquid recovery device 3.6.

[0043] A method for recovering and purifying benzene and styrene organic waste gas, specifically comprising the following steps:

[0044] (1) Benzene waste gas 1.1 and styrene waste gas 2.1 enter benzene waste gas absorption system 1 and styrene waste gas absorption system 2 respectively.

[0045] (2) The benzene waste gas 1.1 is pressurized by the first liquid ring compressor 1.2 and then cooled by the first gas-liquid separator 1.3 and the first cooler 1.4 before entering the first absorption tower 1.5 for absorption. The ethylbenzene lean liquid in the first ethylbenzene lean liquid device 1.7 is cooled by the first condenser 1.6 and then enters the first absorption tower 1.5 for spraying as an absorbent. After the absorption is completed, the liquid enters the first gas-liquid separator 1.3. A part of the liquid enters the first liquid ring compressor 1.2 for circulation as liquid ring compressor liquid, and a part of the liquid enters the first rich liquid distillation device 1.9 through the first circulation pump 1.8 for distillation recovery. After the absorption is completed, the gas enters the organic waste gas adsorption system 3 from the top of the first absorption tower 1.5.

[0046] (3) The styrene waste gas 2.1 is pressurized by the second liquid ring compressor 2.2 and then cooled by the second gas-liquid separator 2.3 and the second cooler 2.4 before entering the second absorption tower 2.5 for absorption. The ethylbenzene lean liquid in the second ethylbenzene lean liquid device 2.7 is cooled by the second condenser 2.6 and then enters the second absorption tower 2.5 for spraying as an absorbent. After the absorption is completed, the liquid enters the second gas-liquid separator 2.3. A part of the liquid enters the second liquid ring compressor 2.2 for circulation as liquid ring compressor liquid, and a part of the liquid enters the second rich liquid distillation device 2.9 through the second circulation pump 2.8 for distillation recovery. After the absorption is completed, the gas enters the organic waste gas adsorption system 3 from the top of the second absorption tower 2.5.

[0047] (4) In steps (2) and (3), the benzene waste gas 1.2 and styrene waste gas 2.2 that pass through the benzene waste gas absorption system 1 and the styrene waste gas absorption system 2 respectively enter the first adsorption unit 3.1 in the organic waste gas adsorption system 3 in the adsorption state. The first adsorption tower 3.1.1 uses the first circulating water pump 3.1.2 to pressurize and the first circulating water cooler 3.1.4 to cool the benzene and styrene waste gases to perform low-temperature deep adsorption. The tail gas is discharged from the top of the first adsorption tower 3.1.1. When the first adsorption desorption unit 3.1.1 is After the first absorption tower 3.1.1 in 3.1 is saturated with adsorption, the benzene waste gas 1.2 and the styrene waste gas 2.2 enter the second adsorption unit 3.2. After the first adsorption unit 3.1 is saturated with adsorption, the first circulating water pump 3.1.2 is used to pressurize and the first circulating water heater 3.1.3 is used to heat for temperature rise desorption regeneration. At this time, the third adsorption tower 3.3.1 in the third adsorption unit 3.3, which is in standby state, is pressurized by the third circulating water pump 3.3.2 and cooled by the third circulating water cooler 3.3.4 to maintain low-temperature cooling.

[0048] (5) The benzene waste gas after desorption by the first desorption unit 3.1 is pressurized by the regeneration vacuum pump 3.4 and condensed by the regeneration condenser 3.5, and then enters the first liquid ring compressor 1.1 for absorption and adsorption again. The styrene waste gas after desorption by the first desorption unit 3.1 is pressurized by the regeneration vacuum pump 3.4 and condensed by the regeneration condenser 3.5, and then enters the second liquid ring compressor 2.1 for absorption and adsorption again.

[0049] The first adsorption unit 3.1, the second adsorption unit 3.2 and the third adsorption unit 3.3 perform adsorption, standby and desorption regeneration alternately.

[0050] Comparative Example 1

[0051] The only difference from the embodiment is that there is no liquid ring compressor, that is, the first liquid ring compressor 1.1 and the second liquid ring compressor 2.1 are not included.

[0052] The concentrations of various gases under the compression conditions with liquid ring (Example) and without liquid ring (Comparative Example 1) are shown in Table 1:

[0053] Table 1 Gas concentrations in Example and Comparative Example 1

[0054]

[0055] Comparative Example 2

[0056] The only difference from the embodiment is that there is no cooler, that is, the first cooler 1.4 and the second cooler 2.4 are not included.

[0057] The concentrations of various gases under cooling conditions (Example) and without cooling conditions (Comparative Example 2) are shown in Table 2:

[0058] Table 2 Gas concentrations in Example 2 and Comparative Example 2

[0059]

[0060] Comparative Example 3

[0061] The only difference from the embodiment is that there is no circulating water pump and circulating water heater, that is, it does not include the first circulating water pump 3.1.2, the first circulating water cooler 3.1.4, the second circulating water pump 3.2.2, the second circulating water cooler 3.2.4, the third circulating water pump 3.3.2, and the third circulating water cooler 3.3.4.

[0062] The concentrations of various gases under normal temperature adsorption conditions (Comparative Example 3) and low temperature adsorption conditions (Example) are shown in Table 3:

[0063] Table 3 Gas concentrations in Example 3 and Comparative Example 3

[0064]

[0065] In addition to the above embodiments, the present invention also includes other implementation modes. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the protection scope of the claims of the present invention.

Claims

1. A benzene and styrene organic waste gas recovery and purification treatment system, the recovery and purification treatment system comprising a benzene waste gas absorption system (1), a styrene waste gas absorption system (2) and an organic waste gas adsorption system (3), the benzene waste gas absorption system (1) and the styrene waste gas absorption system (2) are connected in parallel and are respectively connected to the organic waste gas adsorption system (3); The benzene waste gas absorption system (1) comprises a first liquid ring compressor (1.1), wherein the inlet of the first liquid ring compressor (1.1) is connected to the benzene waste gas (1.2), the outlet of the first liquid ring compressor (1.1) is connected to the first absorption tower (1.5) via a first gas-liquid separator (1.3) and a first cooler (1.4), the upper inlet of the first absorption tower (1.5) is connected to the first ethylbenzene lean liquid device (1.7) via a first condenser (1.6), the bottom outlet of the first absorption tower (1.5) is connected to the side inlet of the first gas-liquid separator (1.3), the bottom outlet of the first gas-liquid separator (1.3) is connected to the first rich liquid distillation device (1.9) via a first circulation pump (1.8), and the top outlet of the first absorption tower (1.5) is connected to the organic waste gas adsorption system (3); The styrene waste gas absorption system (2) comprises a second liquid ring compressor (2.1), the inlet of the second liquid ring compressor (2.1) is connected to the styrene waste gas (2.2), the outlet of the second liquid ring compressor (2.1) is connected to the second gas-liquid separator (2.3) and the second cooler (2.4) in sequence to enter the second absorption tower (2.5), the upper inlet of the second absorption tower (2.5) is connected to the second ethylbenzene lean liquid device (2.7) via the second condenser (2.6), the bottom outlet of the second absorption tower (2.5) is connected to the side inlet of the second gas-liquid separator (2.3), the bottom outlet of the second gas-liquid separator (2.3) is connected to the second rich liquid distillation device (2.9) via the second circulation pump (2.8), and the top outlet of the second absorption tower (2.5) is connected to the organic waste gas adsorption system (3); The organic waste gas adsorption system (3) comprises a first adsorption unit (3.1), a second adsorption unit (3.2), and a third adsorption unit (3.3) connected in parallel. The first adsorption unit (3.1), the second adsorption unit (3.2), and the third adsorption unit (3.3) are connected to a first liquid ring compressor (1.1) and a second liquid ring compressor (2.1) via a regeneration vacuum pump (3.4) and a regeneration condenser (3.5), respectively. The first adsorption unit (3.1) comprises a first adsorption tower (3.1.1), a first circulating water pump (3.1.2), and a first circulating water heater ( 3.1.3), a first circulating water cooler (3.1.4), the bottom inlet of the first adsorption tower (3.1.1) is respectively connected to the top outlet of the first absorption tower (1.5) of the benzene waste gas absorption system (1) and the top outlet of the second absorption tower (2.5) of the styrene waste gas absorption system (2), the first adsorption tower (3.1.1) and the first circulating water pump (3.1.2), the first circulating water heater (3.1.3), and the first circulating water cooler (3.1.4) form a circulation system, and the top of the adsorption tower (3.1.1) is provided with a waste gas outlet that meets the emission standards; The second adsorption unit (3.2) and the third adsorption unit (3.3) have the same structural devices and connection methods as the first adsorption unit (3.1); the second adsorption unit (3.2) includes a second adsorption tower (3.2.1), a second circulating water pump (3.2.2), a second circulating water heater (3.2.3), and a second circulating water cooler (3.2.4); the third adsorption unit (3.3) includes a third adsorption tower (3.3.1), a third circulating water pump (3.3.2), a third circulating water heater (3.3.3), and a third circulating water cooler (3.3.4); The adsorbent of the first absorption tower (3.1.1), the second adsorption tower (3.2.1) and the third adsorption tower (3.3.1) is a silica gel activated carbon mixture, wherein the mass ratio of silica gel to activated carbon is 5:1; The regeneration vacuum pump (3.4) is a dry screw vacuum pump.

2. The benzene and styrene organic waste gas recovery and purification system according to claim 1 is characterized in that: The regeneration condenser (3.5) is also connected to a residual liquid recovery device (3.6).

3. A method for recovering and purifying benzene and styrene organic waste gas, using the benzene and styrene organic waste gas recovery and purification treatment system as claimed in claim 1, characterized in that: The following steps are involved: (1) Benzene waste gas (1.2) and styrene waste gas (2.2) enter the benzene waste gas absorption system (1) and the styrene waste gas absorption system (2) respectively; (2) The benzene waste gas (1.2) is pressurized by the first liquid ring compressor (1.1), cooled by the first gas-liquid separator (1.3) and the first cooler (1.4), and then enters the first absorption tower (1.5) for absorption. The ethylbenzene lean liquid in the first ethylbenzene lean liquid device (1.7) is cooled by the first condenser (1.6) and enters the first absorption tower (1.5) for spraying as an absorbent. After the absorption is completed, the liquid enters the first gas-liquid separator (1.3). A part of the liquid enters the first liquid ring compressor (1.1) and is circulated as liquid ring compressor liquid. A part of the liquid enters the first rich liquid distillation device (1.9) for distillation recovery through the first circulation pump (1.8). After the absorption is completed, the gas enters the organic waste gas adsorption system (3) from the top of the first absorption tower (1.5); (3) The styrene waste gas (2.2) is pressurized by the second liquid ring compressor (2.1), cooled by the second gas-liquid separator (2.3) and the second cooler (2.4), and then enters the second absorption tower (2.5) for absorption. The ethylbenzene lean liquid in the second ethylbenzene lean liquid device (2.7) is cooled by the second condenser (2.6) and enters the second absorption tower (2.5) for spraying as an absorbent. After the absorption is completed, the liquid enters the second gas-liquid separator (2.3). A part of the liquid enters the second liquid ring compressor (2.1) and is circulated as liquid ring compressor liquid. A part of the liquid enters the second rich liquid distillation device (2.9) through the second circulation pump (2.8) for distillation recovery. After the absorption is completed, the gas enters the organic waste gas adsorption system (3) from the top of the second absorption tower (2.5); (4) In steps (2) and (3), the benzene waste gas (1.2) and styrene waste gas (2.2) that have passed through the benzene waste gas absorption system (1) and the styrene waste gas absorption system (2) respectively enter the first adsorption unit (3.1) in the organic waste gas absorption system (3) in an adsorption state. The first adsorption tower (3.1.1) uses the first circulating water pump (3.1.2) to pressurize and the first circulating water cooler (3.1.4) to cool the benzene and styrene waste gases to perform low-temperature deep adsorption. The tail gas is discharged from the top of the first adsorption tower (3.1.1). When the first adsorption tower (3.1.1) is cooled, the benzene and styrene waste gases are discharged. After the first absorption tower (3.1.1) in the adsorption unit (3.1) is saturated with adsorption, the benzene waste gas (1.2) and the styrene waste gas (2.2) enter the second adsorption unit (3.2). After the first adsorption unit (3.1) is saturated with adsorption, the first circulating water pump (3.1.2) is used to pressurize and the first circulating water heater (3.1.3) is used to heat to perform temperature-raising desorption regeneration. At this time, the third adsorption unit (3.3) in the standby state is pressurized by the third circulating water pump (3.3.2) and cooled by the third circulating water cooler (3.3.4) to maintain low-temperature cooling; (5) The benzene waste gas after desorption from the first adsorption unit (3.1) is pressurized by the regeneration vacuum pump (3.4), condensed by the regeneration condenser (3.5), and enters the first liquid ring compressor (1.1) for absorption and adsorption again. The styrene waste gas after desorption from the first adsorption unit (3.1) is pressurized by the regeneration vacuum pump (3.4), condensed by the regeneration condenser (3.5), and enters the second liquid ring compressor (2.1) for absorption and adsorption again.

4. The method for recovering and purifying benzene and styrene organic waste gas according to claim 3, characterized in that: In step (3), the first adsorption unit (3.1), the second adsorption unit (3.2), and the third adsorption unit (3.3) alternately perform adsorption, standby, and desorption regeneration.

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