A refinery dry gas c2+ components recovery system and recovery method

Abstract

The application discloses a refinery dry gas C2 and above component recovery system and recovery method, and belongs to the technical field of pressure swing adsorption gas separation. The system comprises a pressure swing adsorption purification unit, a vacuum pump group connected with the pressure swing adsorption purification unit, a compressor and a rectifying tower, wherein the compressor condensate outlet is connected with a condensate conveying pipe, the condensate conveying pipe is connected to the rectifying tower, the rectifying tower is connected with a recovery product gas conveying pipe and a C4 and above hydrocarbon condensate discharge pipe, the pressure swing adsorption purification unit is connected with a refinery dry gas conveying pipe, the compressor compressed gas outlet is connected with a product gas external conveying pipe, and the recovery product gas conveying pipe is connected to the product gas external conveying pipe. The application can not only recover C2 and C3 components in condensate, but also reduce energy consumption.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of pressure swing adsorption gas separation, and particularly relates to a system and method for recovering C2 and above components in refinery dry gas. BACKGROUND

[0002] The refinery dry gas in a petrochemical plant mainly includes catalytic cracking dry gas, delayed coking dry gas, hydrocracking dry gas, aromatization dry gas, disproportionation dry gas, post-hydrogenation tail gas, and desorption gas of a pressure swing adsorption purification reforming hydrogen device. The refinery dry gas contains a large amount of C2, C3 and other light hydrocarbon components, and these components are raw materials for an ethylene device, so recovering C2 and above components in the refinery dry gas as raw materials for the ethylene device has good economic benefits.

[0003] The methods for recovering C2 and above components from refinery dry gas mainly include cryogenic separation, (shallow cooling, medium cooling) oil absorption, and pressure swing adsorption. The cryogenic separation method has high recovery rate and high purity of C2 and above components. However, the process needs to be pretreated by removing water and carbon dioxide from the raw material gas, and a refrigeration system needs to be configured, which has high energy consumption and large investment. The (shallow cooling, medium cooling) oil absorption method can also achieve a high recovery rate of C2 and above components, but the operating pressure is high, and the raw material gas needs to be compressed to 3.0 MPaG or above, resulting in high energy consumption of the process. The pressure swing adsorption method operates at room temperature and has low operating pressure, and a product gas with high purity of C2 and above components can be obtained at 0.3-1.0 MPaG, which has low energy consumption. With the progress of technology, the recovery rate of C2 and above components by the pressure swing adsorption method has reached a very high level. For example, patent CN104147896B uses a 2-stage method, and the waste gas from the 2-stage pressure swing adsorption is concentrated to further recover C2 and above components as raw material gas for the 1-stage pressure swing adsorption. CN102935324B uses a 3-stage pressure swing adsorption, and the waste gas from the 1-stage and 2-stage pressure swing adsorption is concentrated to further recover C2 and above components as raw material gas for the 1-stage pressure swing adsorption.

[0004] The product gas of the pressure swing adsorption C2 recovery device needs to be compressed and purified before entering the pyrolysis device, and impurities such as sulfur, carbon dioxide, water, and NOx are removed. The heavier refinery dry gas contains C4, C5 and C6 and above components. These heavy components will form condensate after compression and cooling, and a large amount of C2 and C3 components will be dissolved in the condensate, thereby reducing the content of C2 and C3 in the gas product and reducing the recovery rate of C2 and C3.

[0005] CN101063048A, CN106609161A, CN104560194A disclose the process technology of recovering refinery dry gas by oil absorption method, and the method of recovering carbon two and carbon three components in the compression condensate during the compression of the raw material gas. CN101063048A sends the compression condensate to the main absorption tower, CN106609161A sends the compression condensate to the gasoline stabilizing tower, and CN104560194A sends the compression condensate to the condensate stripping tower. Since the operating pressure of the oil absorption method is high, at 3.0-5.0 MPaG, the compression condensate is relatively large, the steam consumption is large when recovering the carbon two components in the recovery condensate, and thus the energy consumption of the entire recovery process is increased.

[0006] The carbon two product recovered by the pressure swing adsorption adsorption pressure method is at normal pressure, the pressure of the subsequent refining process is generally at 1.2-1.6 MPaG, which is much lower than the operating pressure of the oil absorption method, and thus the condensate amount is small. In order to recover the carbon two component product in the condensate and reduce the energy consumption of the process as much as possible, it is urgent to develop an equipment for improving the recovery rate of carbon two and carbon three components, so as to optimize the existing process flow and improve the device benefit. SUMMARY

[0007] The purpose of the present application is to provide a refinery dry gas carbon two and above component recovery system, which recovers carbon two and carbon three components in the condensate by adding a rectifying device after the compression device, and uses the waste heat of the process gas of the system power equipment to heat the condensate, so as to save the energy consumption while recovering the carbon two and carbon three components.

[0008] Another purpose of the present application is to provide a refinery dry gas carbon two and above component recovery method, which is carried out by using the above-mentioned system.

[0009] In order to achieve the above-mentioned purposes, the technical scheme adopted by the present application is as follows:

[0010] A refinery dry gas carbon two and above component recovery system, the system comprises a pressure swing adsorption purification unit, a vacuum pump set and a compressor connected with the pressure swing adsorption purification unit respectively, characterized in that it further comprises a rectifying tower, a condensate delivery pipe is connected to the condensate outlet of the compressor, the condensate delivery pipe is connected to the rectifying tower, the rectifying tower is connected with a recovered product gas delivery pipe and a carbon four and above hydrocarbon condensate discharge pipe, a refinery dry gas delivery pipe is connected to the pressure swing adsorption purification unit, a product gas delivery pipe is connected to the product gas outlet of the compressor, and the recovered product gas delivery pipe is connected to the product gas delivery pipe.

[0011] Further, an oil-water separator is arranged on the recovered product gas delivery pipe.

[0012] Further, an oil-water separator is arranged on the recovered product gas delivery pipe.

[0013] Further, the liquid pump is arranged on the infusion pipe, and the oil-water separator is connected with the oil and sewage discharge pipe.

[0014] Further, the first circulating water cooler is arranged on the recovered product gas conveying pipe.

[0015] Further, the first circulating water cooler and the oil-water separator are sequentially arranged along the gas flow direction on the recovered product gas conveying pipe.

[0016] Further, the first heat exchanger is arranged on the condensate conveying pipe and the process gas conveying pipe connected between the compressors.

[0017] Further, the second heat exchanger is arranged on the condensate conveying pipe and the carbon four and above hydrocarbon condensate discharge pipe.

[0018] Further, the second circulating water cooler is arranged on the carbon four and above hydrocarbon condensate discharge pipe, and the second heat exchanger and the second circulating water cooler are sequentially arranged along the liquid flow direction on the carbon four and above hydrocarbon condensate discharge pipe.

[0019] Further, the circulating heating pipe is connected to the rectifying tower, and the steam heater is arranged on the circulating heating pipe.

[0020] The refinery dry gas carbon two and above component recovery method provided by the present application is implemented by using the system.

[0021] In some embodiments of the present application, the recovery method comprises the following steps:

[0022] Step 1. Pressure swing adsorption: the refinery dry gas enters the pressure swing adsorption purification unit for purification, and the purified product gas enters the compressor, and the remaining hydrogen, nitrogen, methane and other weak adsorbents are discharged as waste gas;

[0023] Step 2. Compression: the product gas purified by the pressure swing adsorption is compressed from 0.01 MPaG to 1.4 MPaG, and part of the carbon two and above product gas after the secondary compression is returned to the pressure swing adsorption purification unit as the displacement gas; the compressed condensate and the process gas at the third outlet of the compressor are heat exchanged in the first heat exchanger; the product gas after the third compression is discharged through the product gas external conveying pipe and sent to the downstream purification process;

[0024] Step 3. Rectification: the compressed condensate separated from the compressor is sent to the rectifying tower for rectification after heat exchange, and the carbon two and carbon three components in the condensate are recovered; the carbon two and carbon three components are separated from the compressed condensate, enter the gas phase from the liquid phase, are discharged from the rectifying tower, are separated after liquid separation, and then enter the product gas external conveying pipe and are mixed into the carbon two and above product gas;

[0025] The compressed condensate is separated into C2 and C3 components in a distillation tower to obtain C4 and above hydrocarbons. After the C4 and above hydrocarbons are discharged from the distillation tower, they exchange heat with the compressed condensate in the second heat exchanger and are then cooled in the second circulating water cooler to the final discharge system.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention has a simple structure, a scientific and reasonable design, and is easy to use. By arranging the waste heat of the process gas of the distillation unit and the recovery unit power equipment, the recovery rate of the C2 and C3 components can be increased by 3% to 15%, and the steam consumption of the distillation unit can be reduced by 40% to 55%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of the present invention.

[0029] The names corresponding to the reference numerals are:

[0030] 1-pressure swing adsorption purification unit, 2-compressor, 3-distillation tower, 4-condensate delivery pipe, 5-product gas external transmission pipe, 6-refinery dry gas delivery pipe, 7-C4 and above hydrocarbon condensate external discharge pipe, 8-recovered product gas delivery pipe, 9-vacuum pump group, 10-first circulating water cooler, 11-oil-water separator, 12-liquid delivery pipe, 13-liquid pump, 14-oil and wastewater external discharge pipe, 15-process gas delivery pipe, 16-first heat exchanger, 17-second heat exchanger, 18-second circulating water cooler, 19-circulating heating pipe, 20-steam heater. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] Example 1

[0033] like Figure 1 As shown, the present invention provides a system for recovering C2 and above components from refinery dry gas, comprising a pressure swing adsorption purification unit 1, a vacuum pump group 9, a compressor 2 and a distillation tower 3. The pressure swing adsorption purification unit 1 is connected to the vacuum pump group 9 and the compressor 2 respectively.

[0034] The pressure swing adsorption purification unit 1 is connected to a refinery dry gas transmission pipeline 6 .

[0035] The compressed gas outlet of compressor 2 is connected to the product gas transmission pipe 5, the condensate outlet of compressor 2 is connected to the condensate transmission pipe 4, the condensate transmission pipe 4 is connected to the distillation tower 3, the distillation tower 3 is connected to the recovery product gas transmission pipe 8 and the C4 and above hydrocarbon condensate discharge pipe 7, the recovery product gas transmission pipe 8 is connected to the product gas transmission pipe 5.

[0036] The vacuum pump in the vacuum pump group 9 is a reciprocating pump, and the compressor 2 is a reciprocating compressor.

[0037] Example 2

[0038] like Figure 1 As shown, the present invention provides a system for recovering C2 and above components from refinery dry gas, comprising a pressure swing adsorption purification unit 1, a vacuum pump group 9, a compressor 2 and a distillation tower 3. The pressure swing adsorption purification unit 1 is connected to the vacuum pump group 9 and the compressor 2 respectively.

[0039] The pressure swing adsorption purification unit 1 is connected to a refinery dry gas transmission pipeline 6 .

[0040] The compressed gas outlet of compressor 2 is connected to a product gas transmission pipe 5, and the condensate outlet of compressor 2 is connected to a condensate transmission pipe 4, which is connected to a distillation tower 3. The distillation tower 3 is connected to a recovered product gas transmission pipe 8 and a C4 and above hydrocarbon condensate discharge pipe 7, and the recovered product gas transmission pipe 8 is connected to the product gas transmission pipe 5. The vacuum pump in the vacuum pump group 9 is a reciprocating pump, and the compressor 2 is a reciprocating compressor.

[0041] The recovered product gas delivery pipe 8 is provided with a first circulating water cooler 10 and an oil-water separator 11 , which are sequentially distributed on the recovered product gas delivery pipe 8 along the direction of the air flow.

[0042] The liquid outlet of the oil-water separator 11 is connected to a liquid infusion pipe 12, which is connected to the distillation tower 3. A liquid pump 13 is provided on the liquid infusion pipe 12, and the oil-water separator 11 is connected to an oily wastewater discharge pipe 14.

[0043] This second embodiment provides a more preferred structure based on the first embodiment. Specifically, a first circulating water cooler 10 and an oil-water separator 11 are provided on the recovered product gas delivery pipe 8. The first circulating water cooler 10 and the oil-water separator 11 are arranged sequentially along the recovered product gas delivery pipe 8 along the direction of gas flow. The liquid outlet of the oil-water separator 11 is connected to a liquid infusion pipe 12, which is connected to the distillation tower 3. A liquid pump 13 is provided on the liquid infusion pipe 12, and the oil-water separator 11 is connected to an oily wastewater discharge pipe 14.

[0044] Example 3

[0045] like Figure 1As shown, the refinery dry gas C2+ component recovery system provided by the present application comprises a pressure swing adsorption purification unit 1, a vacuum pump set 9, a compressor 2, a rectifying tower 3, a first heat exchanger 16, a second heat exchanger 17 and a second circulating water cooler 18.

[0046] The pressure swing adsorption purification unit 1 is connected with the vacuum pump set 9 and the compressor 2 respectively.

[0047] The pressure swing adsorption purification unit 1 is connected with a refinery dry gas delivery pipe 6.

[0048] The compressed gas outlet of the compressor 2 is connected with a product gas delivery pipe 5, and the condensed liquid outlet of the compressor 2 is connected with a condensed liquid delivery pipe 4, which is connected with the rectifying tower 3. The rectifying tower 3 is connected with a recovered product gas delivery pipe 8 and a C4+ hydrocarbon condensed liquid discharge pipe 7, and the recovered product gas delivery pipe 8 is connected with the product gas delivery pipe 5. The vacuum pump in the vacuum pump set 9 is a reciprocating pump, and the compressor 2 is a reciprocating compressor.

[0049] The recovered product gas delivery pipe 8 is provided with a first circulating water cooler 10 and an oil-water separator 11, which are sequentially arranged along the gas flow direction on the recovered product gas delivery pipe 8.

[0050] The oil-water separator 11 is connected with a liquid delivery pipe 12, which is connected with the rectifying tower 3. The liquid delivery pipe 12 is provided with a liquid pump 13, and the oil-water separator 11 is connected with an oil and dirt water discharge pipe 14.

[0051] The first heat exchanger 16 is connected with the condensed liquid delivery pipe 4 and a process gas delivery pipe 15 connected between the compressor 2.

[0052] The second heat exchanger 17 is connected with the condensed liquid delivery pipe 4 and the C4+ hydrocarbon condensed liquid discharge pipe 7.

[0053] The second circulating water cooler 18 is arranged on the C4+ hydrocarbon condensed liquid discharge pipe 7, and the second heat exchanger 17 and the second circulating water cooler 18 are sequentially arranged along the liquid flow direction on the C4+ hydrocarbon condensed liquid discharge pipe 7.

[0054] The more preferred structure of the present application is provided based on the embodiment 2, and specifically, the recovery system further comprises the first heat exchanger 16, the second heat exchanger 17 and the second circulating water cooler 18. The first heat exchanger 16 is connected with the condensed liquid delivery pipe 4 and the process gas delivery pipe 15 connected between the compressor 2. The second heat exchanger 17 is connected with the condensed liquid delivery pipe 4 and the C4+ hydrocarbon condensed liquid discharge pipe 7. The second circulating water cooler 18 is arranged on the C4+ hydrocarbon condensed liquid discharge pipe 7, and the second heat exchanger 17 and the second circulating water cooler 18 are sequentially arranged along the liquid flow direction on the C4+ hydrocarbon condensed liquid discharge pipe 7.

[0055] Example 4

[0056] like Figure 1 As shown, the present invention provides a system for recovering C2 and above components in refinery dry gas, comprising a pressure swing adsorption purification unit 1, a vacuum pump group 9, a compressor 2, a distillation tower 3, a first heat exchanger 16, a second heat exchanger 17 and a second circulating water cooler 18.

[0057] The pressure swing adsorption purification unit 1 is connected to the vacuum pump group 9 and the compressor 2 respectively.

[0058] The pressure swing adsorption purification unit 1 is connected to a refinery dry gas transmission pipeline 6 .

[0059] The compressed gas outlet of compressor 2 is connected to a product gas transmission pipe 5, and the condensate outlet of compressor 2 is connected to a condensate transmission pipe 4, which is connected to a distillation tower 3. The distillation tower 3 is connected to a recovered product gas transmission pipe 8 and a C4 and above hydrocarbon condensate discharge pipe 7, and the recovered product gas transmission pipe 8 is connected to the product gas transmission pipe 5. The vacuum pump in the vacuum pump group 9 is a reciprocating pump, and the compressor 2 is a reciprocating compressor.

[0060] The recovered product gas delivery pipe 8 is provided with a first circulating water cooler 10 and an oil-water separator 11 , which are sequentially distributed on the recovered product gas delivery pipe 8 along the direction of the air flow.

[0061] The liquid outlet of the oil-water separator 11 is connected to a liquid infusion pipe 12, which is connected to the distillation tower 3. A liquid pump 13 is provided on the liquid infusion pipe 12, and the oil-water separator 11 is connected to an oily wastewater discharge pipe 14.

[0062] The first heat exchanger 16 is respectively connected to the condensate conveying pipe 4 and the process gas conveying pipe 15 connected between the compressors 2 .

[0063] The second heat exchanger 17 is connected to the condensate delivery pipe 4 and the C4 and above hydrocarbon condensate discharge pipe 7 respectively.

[0064] The second circulating water cooler 18 is provided on the C4 and above hydrocarbon condensate discharge pipe 7 , and the second heat exchanger 17 and the second circulating water cooler 18 are sequentially distributed on the C4 and above hydrocarbon condensate discharge pipe 7 along the liquid flow direction.

[0065] The distillation tower 3 is connected to a circulation heating pipe 19 , and a steam heater 20 is provided on the circulation heating pipe 19 .

[0066] This embodiment 4 provides a more preferred structure based on embodiment 3, specifically: a circulating heating pipe 19 is connected to the distillation tower 3, and a steam heater 20 is provided on the circulating heating pipe 19.

[0067] Example 5

[0068] This embodiment recovers refinery dry gas C2+ components using the system described in Example 4, specifically:

[0069] The pressure swing adsorption purification unit 1 uses a vacuum pressure swing adsorption process, and the vacuum pump set 9 uses a reciprocating pump. The refinery dry gas enters the pressure swing adsorption purification unit 1, and after purification by the vacuum pressure swing adsorption process, the methane content in the C2+ component product is reduced to below 5 vol%, and the remaining hydrogen, nitrogen, methane, and other weak adsorbents are discharged as waste gas.

[0070] The product gas after purification by the pressure swing adsorption purification unit 1 enters the compressor 2, and as an optimization, the compressor 2 uses a reciprocating compressor to compress the C2+ product gas from the pressure swing adsorption purification unit 1 from 0.01 MPaG to 1.4 MPaG, with the second-stage compression outlet pressure being 0.47 MPaG and the third-stage compression outlet pressure being 1.4 MPaG. Part of the C2+ product gas after second-stage compression is returned to the pressure swing adsorption purification unit 1 as displacement gas; the compressed condensate and the process gas at the third-stage outlet of the compressor are heat-exchanged in the first heat exchanger 16.

[0071] The product gas after third-stage compression is discharged through the product gas export pipe 5, and then undergoes subsequent heat exchange, cooling, and liquid separation before being sent to the downstream purification process as product gas. The compressed condensate separated by the compressor 2 is heat-exchanged in the second heat exchanger 17 and then sent to the rectification tower 3 to recover the C2 and C3 components in the condensate.

[0072] Specifically, the condensate after heat exchange in the second heat exchanger 17 enters the rectification tower 3, and after the compressed condensate is warmed in the rectification tower 3, the C2 and C3 components are separated from the compressed condensate, enter the gas phase from the liquid phase, and are discharged through the recovery product gas delivery pipe 8 of the rectification tower 3, and then are cooled in the first circulating water cooler 10 and separated into liquid and gas in the oil-water separator 11 before being sent to the product gas export pipe 5 and entering the C2+ product gas. The water separated in the oil-water separator 11 is discharged from the system as waste water, and the hydrocarbons separated in the oil-water separator 11 are sent to the rectification tower 3 through the liquid pump 13.

[0073] The rectification tower 3 uses steam heating, and the C4+ hydrocarbons after rectification of the compressed condensate are discharged from the rectification tower 3, heat-exchanged with the compressed condensate in the second heat exchanger 17, and then cooled to 40°C by the second circulating water cooler 18 before being discharged from the system.

[0074] The composition of the refinery dry gas is shown in Table 1, and the C2+ product gas obtained after pressure swing adsorption purification is shown in Table 2, with a flow rate of 16000 Nm 3 / h, wherein the flow rate of C2-C3 is 543.64 kmol / h; the condensed liquid (except water) produced after compression by the compression unit to 1.4 MPaG is 102.26 kmol / h, and the C2-C3 component recovered by the rectification unit is 49.13 kmol / h, i.e. the total yield of carbon two and carbon three can be increased by 9.04%. The rectification process consumes steam 454.3 kg / h, and the steam consumption when the heat of the process gas is recovered by the compressor is 630.7 kg / h, i.e. the heat recovery by the power equipment can reduce the steam consumption by 30%.

[0075] Table 1 Composition of raw gas

[0076]

[0077] Table 2 Composition of product gas of the pressure swing adsorption section

[0078]

[0079] Finally, it should be noted that: the above embodiments are merely the preferred embodiments of the present application for describing the technical solutions of the present application, but not limiting them, and of course, not limiting the patent scope of the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application; that is to say, any modification or polishing without substantial significance in the main design idea and spirit of the present application, and the technical problems solved are still consistent with the present application, and should be included in the protection scope of the present application; in addition, the technical solutions of the present application are directly or indirectly applied to other related technical fields, which are also included in the protection scope of the present application.

Claims

1. A refinery dry gas C2+ components recovery system comprising a pressure swing adsorption purification unit (1), a vacuum pump set (9) and a compressor (2) connected to the pressure swing adsorption purification unit (1) respectively, characterized in that, The system further comprises a rectification tower (3), a condensate delivery pipe (4) connected to the condensate outlet of the compressor (2), the condensate delivery pipe (4) being connected to the rectification tower (3), the rectification tower (3) being connected to a recovered product gas delivery pipe (8) and a carbon four and above hydrocarbon condensate discharge pipe (7), the pressure swing adsorption purification unit (1) being connected to a refinery dry gas delivery pipe (6), and the product gas delivery pipe (5) being connected to the compressed gas outlet of the compressor (2); The recovery system further comprises a first heat exchanger (16) and a second heat exchanger (17); the first heat exchanger (16) is connected to the condensate delivery pipe (4) and a process gas delivery pipe (15) connected between the compressor (2); the second heat exchanger (17) is connected to the condensate delivery pipe (4) and the carbon four and above hydrocarbon condensate discharge pipe (7); the condensate after heat exchange in the second heat exchanger (17) enters the rectification tower (3); the compressed condensate is heated in the rectification tower (3), and the carbon two and carbon three components are separated from the compressed condensate, enter the gas phase from the liquid phase, are discharged from the rectification tower through the recovered product gas delivery pipe (8), are cooled through the first circulating water cooler (10), are separated into oil and water in the oil-water separator (11), enter the product gas delivery pipe (5), and are mixed into the carbon two and above product gas; The recovery system further comprises a second circulating water cooler (18) arranged on the carbon four and above hydrocarbon condensate discharge pipe (7); the second heat exchanger (17) and the second circulating water cooler (18) are sequentially arranged along the liquid flow direction on the carbon four and above hydrocarbon condensate discharge pipe (7).

2. The refinery dry gas C2+ components recovery system of claim 1, wherein, The oil-water separator (11) is connected to a liquid delivery pipe (12).

3. The refinery dry gas C2+ components recovery system of claim 2, wherein, The liquid delivery pipe (12) is provided with a liquid pump (13), and the oil-water separator (11) is connected to an oil and sewage discharge pipe (14).

4. The refinery dry gas C2+ components recovery system of claim 1 wherein, The rectification tower (3) is connected to a circulating heating pipe (19), and the circulating heating pipe (19) is provided with a steam heater (20).

5. A refinery dry gas C2+ components recovery process characterized by, The system of any one of claims 1-4 is used; comprising the following steps: Step 1. Pressure swing adsorption: the refinery dry gas enters the pressure swing adsorption purification unit for purification, the purified product gas enters the compressor, and the remaining hydrogen, nitrogen, methane and other weak adsorbents are discharged as waste gas; Step 2. Compression: the product gas purified by the pressure swing adsorption purification unit is compressed from 0.01 MPaG to 1.4 MPaG, a part of the carbon two and above product gas after secondary compression is returned to the pressure swing adsorption purification unit as displacement gas; the compressed condensate and the process gas at the third outlet of the compressor are heat exchanged in the first heat exchanger; the product gas after third compression is discharged through the product gas delivery pipe and sent to the downstream purification process; Step 3. Rectification: the compressed condensate separated from the compressor is sent to the rectification tower for rectification after heat exchange, and the carbon two and carbon three components in the recovered condensate are separated; the carbon two and carbon three components are separated from the compressed condensate, enter the gas phase from the liquid phase, are discharged from the rectification tower, are separated into oil and water, enter the product gas delivery pipe, and are mixed into the carbon two and above product gas. The compressed condensate is separated from carbon two and carbon three components by the rectifying tower to obtain hydrocarbons with carbon four and above. The hydrocarbons with carbon four and above are discharged from the rectifying tower, heat exchanged with the compressed condensate in the second heat exchanger, and then cooled by the second circulating water cooler to be discharged to the system.

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