A flare gas recovery device

Abstract

The present invention discloses a flare gas recovery device, which belongs to the technical field of flare gas recovery. The device comprises a PLC controlled by the whole machine, a water seal tank, a dry gas holder, a discharge tank, a back pressure tank and a joint control valve unit, wherein a demister is arranged on the inner upper part of the water seal tank; the lower part of the water seal tank is connected to the flare gas inlet pipe through a first one-way valve; the flare gas inlet pipe is connected to a second one-way valve at the input end of the first one-way valve; the second one-way valve is connected to the dry gas holder through a first electric control valve; the top of the water seal tank is connected between the second one-way valve and the first electric control valve through a third one-way valve; the bottom of the water seal tank is connected to the discharge tank through a double valve group; the double valve groups are connected to the upper part of the water seal tank through a discharge valve; the back pressure tank is connected to the bottom of the discharge tank through a back pressure valve. The flare gas recovery device of the present invention can fully recycle and utilize the flare gas, improve the application value of the flare gas, and can quickly handle the flare gas in an emergency.

Description

Technical Field

[0001] The invention specifically relates to a flare gas recovery device, and belongs to the technical field of flare gas recovery. Background Art

[0002] The main components of flare gas are hydrogen, ethylene, aromatic hydrocarbons, acetaldehyde, catalytic materials and other toxic, harmful, flammable and explosive gases; there are usually two ways to deal with this gas, one is the raw material type, that is, the flare gas is turned into a raw material or a finished product of the process, and the other is the fuel type, which is the method adopted by most factories; the existing flare gas recovery device, such as the Chinese patent publication number: CN104549051A, discloses a flare gas recovery device, including a frame, a pressurizing unit, a reactor, a conveying pipeline, a pressure reducing tank, a waste liquid Pool, flare tower, the gas recovery device, through the pressure unit to transfer the liquid methane in the reactor through the transmission pipeline to the pressure reducing tank, and then the pressure reducing pump on the outer wall of the pressure reducing tank reduces the pressure of the liquid methane, the waste liquid after decompression will enter the waste liquid pool, and the methane gas will return to the reactor through the reflux pipe and be recycled again, but the flare gas recovery device is only suitable for a single flare gas component, can not realize the recovery and application of complex components of flare gas, easy to cause the direct combustion and emission of flare gas, or the low calorific value and high application value gas is only used as fuel gas, can not give full play to the application value. Summary of the invention

[0003] In order to solve the above problems, the present invention proposes a flare gas recovery device, which can fully recycle and utilize the flare gas, improve the application value of the flare gas, and can quickly handle the flare gas in an emergency.

[0004] The flare gas recovery device of the present invention comprises:

[0005] PLC for whole machine control;

[0006] A water seal tank, wherein a demister is arranged at the upper inner portion of the water seal tank; the lower portion of the water seal tank is connected to the flare gas inlet pipe via a first one-way valve;

[0007] Dry gas holder, the flare gas inlet pipe is connected to a second one-way valve at the input end of the first one-way valve; the second one-way valve is connected to the dry gas holder through a first electric control valve; the top of the water seal tank is connected between the second one-way valve and the first electric control valve through a third one-way valve;

[0008] The bottom of the water seal tank is connected to the discharge tank through a double valve group; the double valve group is connected to the upper part of the water seal tank through a relief valve;

[0009] A back-pressure tank, wherein the back-pressure tank is connected to the bottom of the discharge tank through a back-pressure valve, the top of the back-pressure tank is connected to the top of the water seal tank through an air supply valve, and a first pressure transmitter is provided on the top of the back-pressure tank;

[0010] The joint control valve unit includes a safety relief valve installed on the top of the water seal tank, a first flare gas supply valve and a second pressure transmitter; the output ends of the safety relief valve and the first flare gas supply valve are connected to the flare equipment. When the water seal tank is working, the flare gas breaks through the water seal. When the second pressure transmitter detects that the pressure value reaches the set value, the first flare gas supply valve opens and the flare gas is discharged to the flare equipment; when the first flare gas supply valve or the second pressure transmitter fails, or a large displacement occurs to cause the water seal tank to continue to rise, the safety relief valve is directly opened, so that the flare gas can be sent to the flare equipment, so that the water seal tank is continuously in a safe operating state.

[0011] The flare gas inlet pipe sends the flare gas into the water seal tank through the first one-way valve, and due to the water seal effect of the water seal tank, the flare gas cannot break through the water seal tank, and the flare gas is sent to the dry gas holder through the second one-way valve and the first electric control valve; when the flare gas partially penetrates through the water seal of the water seal tank, the flare gas with a large flow rate can be synchronously absorbed into the flare gas with a large flow rate during the process of passing through the second one-way valve and the first electric control valve, so as to fully recover the flare gas; when a production line fails, resulting in a large displacement state in the flare gas inlet pipe or a dry gas holder fails, the double valve group acts quickly, and the water seal tank quickly sends the water seal into the discharge tank; at this time, a large displacement of flare gas enters the water seal tank through the flare gas inlet pipe, and breaks through the water seal of the water seal tank and enters the flare device Before entering the flare equipment, the flare gas is supplied to the water seal tank through the air supply valve until the first pressure transmitter monitors the set pressure value, then the air supply valve is closed, and the joint control valve unit is opened to supply gas to the flare equipment; when the production line and the dry gas holder are restored, the joint control valve unit is closed, the back pressure valve is opened, and the high-pressure flare gas in the discharge tank drives the water seal in the discharge tank into the water seal tank, and then the valve body above the double valve group is closed, the back pressure valve is closed, and then the air relief valve is opened to send the flare gas in the discharge tank to the top of the water seal, and the first electric control valve is opened to realize the delivery of the flare gas to the dry gas holder; finally, the valve body below the double valve group is closed, and the valve body above the double valve group is opened, so as to discharge the remaining gas to the top of the water seal, and finally the air relief valve and the valve body above and below the double valve group are closed.

[0012] Further, the output end of the first electric control valve is connected to the acid gas rough absorption unit, and the output end of the acid gas rough absorption unit is connected to the acid gas fine absorption unit; the output end of the acid gas fine absorption unit is connected to the solid-liquid separator, the discharge end of the solid-liquid separator is connected to the liquid storage tank, the exhaust end of the solid-liquid separator is connected to the pressurizing valve, the pressurizing valve is connected to the compressor, the output end of the compressor is connected to the intermediate pressure control tank through a fourth one-way valve, the top of the intermediate pressure control tank is connected with a third pressure transmitter and a cryogenic pressure control valve, and the cryogenic pressure control valve is connected to a cryogenic dryer through a pressure equalizing valve; the bottom of the intermediate pressure control tank and the cryogenic dryer are connected to the liquid storage tank; the exhaust end of the cryogenic dryer is connected to the gas separation unit, and the output end of the gas separation unit is connected to the dry gas holder through a fifth one-way valve; the separation end of the gas separation unit is connected to the pure gas storage tank through a separation one-way valve; the pure gas storage tank is connected to the gas application pipeline through a reuse valve; the dry gas holder is connected to the fuel gas pipeline network through a fuel gas supply valve.

[0013] The flare gas is blocked by a water seal tank and enters the acid gas rough absorption unit through the first electric control valve. After passing through the acid gas rough absorption, the flare gas enters the acid gas fine absorption unit for fine absorption and is finally sent to the solid-liquid separator for solid-liquid separation. The separated liquid is sent to the liquid storage tank for temporary storage. The separated gas is sent to the compressor through a pressure boosting valve. After being pressurized by the compressor, the compressed flare gas enters the intermediate pressure control tank through the fourth one-way valve. After the intermediate pressure control tank reaches the set pressure, the flare gas intermittently supplies gas to the cryogenic dryer through the cryogenic pressure control valve, so that the cryogenic dryer works intermittently to avoid energy waste of the cryogenic dryer; after completing cryogenic drying, the dry flare gas is sent to the gas separation unit to separate the target gas, and is sent to the pure gas storage tank through the separation one-way valve, and the target gas is sent to the gas application pipeline (product line or production line) through the pure gas storage tank; the remaining fraction of the flare gas is sent to the dry gas holder, and gas fuel is provided to the fuel gas pipeline network through the fuel supply valve.

[0014] Furthermore, the dry gas holder is connected to the flare equipment through a second flare gas supply valve. When the air pressure of the dry gas holder reaches the set warning value and the fuel gas supply valve is in a closed state, the second flare gas supply valve is opened to send the gas in the dry gas holder to the flare equipment, and the gas is continuously consumed by the flare equipment until the air pressure of the dry gas holder drops to the set safety value; the second flare gas supply valve is closed.

[0015] Furthermore, a gas detection transmitter is connected in series between the cryogenic dryer and the gas separation unit, and a bypass valve is provided at the output end of the cryogenic dryer. The bypass valve is connected in parallel to the input and output ends of the gas separation unit, and the bypass valve is connected to the fifth one-way valve. After the flare gas completes cryogenic drying, the flare gas enters the gas separation unit. Before the flare gas enters the gas separation unit, the target gas components are monitored by the gas detection transmitter. When no target gas components are found, the gas separation unit is bypassed by the bypass valve, and the flare gas enters the gas separation unit of the next level, which can improve the flare gas processing efficiency and extend the working cycle and service life of the gas separation unit.

[0016] Furthermore, the acid gas rough absorption unit and the acid gas fine absorption unit both include an absorption tower, an atomizing spray head is arranged at the upper inner side of the absorption tower, and the atomizing spray head is connected to the bottom of the absorption tower through an atomizing pump; a liquid replenishing valve is arranged at the input end of the atomizing pump, and the liquid replenishing valve is connected to a high-position absorption liquid supply pipe group; an air inlet flange is arranged at the lower part of the absorption tower, and an overflow valve is arranged at the lower part of the air inlet flange of the absorption tower; the overflow valve of the acid gas rough absorption unit is connected to the overflow tank; the overflow valve of the acid gas fine absorption unit is connected to the absorption liquid supply pipe group. When the acid gas rough absorption unit is working, the flare gas enters the absorption tower, and the absorption tower can directly neutralize the acid and alkali, or use an absorbent for absorption. For example, ethanolamine is used as the absorption liquid, and the absorption liquid is sprayed through an atomizing spray head. The absorption liquid contacts the flare gas, and the atomizing spray liquid can absorb the large acid fractions in the mixed gas containing hydrocarbons, such as carbon dioxide and sulfides. After the acid gas in the flare gas is absorbed by the acid gas rough absorption unit, it enters the acid gas fine absorption unit, and the acid gas fine absorption unit performs secondary acid absorption on the flare gas that has completed the first acid absorption. Finally, the absorption liquid is sent to the stripping equipment through the overflow tank, and the acid gas absorbed by the absorption tower can be desorbed by stripping through the stripping equipment to recover the acid gas.

[0017] Furthermore, the gas separation units are provided in multiple groups, and the separation objects of each group of the gas separation units are different; the exhaust end of the gas separation units of the previous group is connected to the inlet end of the gas separation units of the next group; the flare gas is separated into one or more components through the previous group of gas separation units, and the target single component is obtained through distillation; after one or more gases are separated from the flare gas, it is sent to the next group of gas separation units, and after multiple separations are completed, the remaining components in the flare gas are sent to the dry gas cabinet.

[0018] Furthermore, the gas separation unit is one or more of a pressure swing adsorption device, a temperature swing adsorption device and a membrane separation device; for example, in the flare gas, a single component fraction or a composite fraction is directly separated by the gas separation unit, such as separating the composite fraction of hydrogen and methane into a hydrogen fraction and a methane fraction by a pressure swing adsorption fraction. Specifically, the hydrogen and methane fractions enter the pressure swing adsorption device, the hydrogen component that is not easily adsorbed passes through the adsorption tower and is discharged from the pressure swing adsorption device (pressure swing adsorption tower), and the gas components such as methane that are easily adsorbed are retained in the adsorption tower.

[0019] Furthermore, the output end of the separation check valve is connected to a distillation device, and the exhaust end of the waste gas of the distillation device is connected to a dry gas holder; the distillation end of the distillation device is connected to a pure gas storage tank; during operation, the flare gas is sent to a gas separation unit, and a high-value target fraction is separated by the gas separation unit, such as one or more of hydrogen, ethylene, methane, aromatic hydrocarbons, acetaldehyde and catalytic materials are separated respectively, and the target fraction is sent to the distillation device, and the target fraction is enriched again by the distillation equipment, and the waste gas generated in the distillation process is sent to a dry gas holder; the enriched target fraction is sent to a pure gas storage tank, waiting for application in a product line or production line.

[0020] Compared with the prior art, the flare gas recovery device of the present invention, under normal conditions of the water seal tank, seals the gas through the joint control valve unit, and continuously sends the flare gas into the dry gas holder through the second one-way valve. When part of the flare gas permeates through the water seal to form permeated gas, since the flare gas quickly flows through the second one-way valve, the permeated gas can be quickly and synchronously pumped to the dry gas holder, so that the flare gas can be fully recycled and utilized to avoid the waste of the flare gas. Before the flare gas enters the dry gas holder, the gas detection transmitter is used to accurately monitor whether there is a target gas in the transmitted flare gas. When the target gas is present, The target gas can be quickly separated and distilled and stored in a pure gas storage tank, which can deliver the high-value target gas to the product line or production line through a gas application pipeline. Finally, the low-value mixed gas in the flare gas is delivered to the dry gas holder, and gas fuel is provided to the production line through the fuel supply valve and the fuel gas pipeline network, which can improve the application value of the flare gas. When an accident occurs on the production line, causing the flare gas discharge to exceed the set value or an accident occurs in the dry gas holder, the water seal can be quickly released and the flare gas can be delivered to the flare equipment to achieve rapid emergency treatment of the flare gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the flare gas recovery device of the present invention.

[0022] Figure 2 It is a schematic diagram of the connection structure of various components between the first electric control valve and the dry gas cabinet of the present invention.

[0023] Figure 3For the present invention Figure 2 Schematic diagram of the local enlarged structure at point A in the middle.

[0024] Figure 4 This is a schematic diagram of the structure of the second flare gas supply valve connected to the flare gas recovery device of the present invention.

[0025] Figure 5 This is a schematic diagram of the structure of the gas separation unit of the flare gas recovery device of the present invention connected with a bypass valve.

[0026] Figure 6 This is a schematic diagram of the structure of the distillation equipment connected to the flare gas recovery device of the present invention.

[0027] Figure numerals: 1, water seal tank, 2, demister, 3, first non-return valve, 4, flare gas inlet pipe, 5, dry gas holder, 6, second non-return valve, 7, first electric control valve, 8, discharge tank, 9, double valve group, 10, relief valve, 11, back pressure tank, 12, back pressure valve, 13, air supply valve, 14, first pressure transmitter, 15, safety relief valve, 16, first flare gas supply valve, 17, second pressure transmitter, 18, flare equipment, 19, acid gas rough absorption unit, 20, acid gas fine absorption unit, 21, solid-liquid separator, 22, liquid storage tank, 23, pressurizing valve, 24, compressor, 25 , the fourth one-way valve, 26, the intermediate pressure control tank, 27, the third pressure transmitter, 28, the cryogenic pressure control valve, 29, the equalizing valve, 30, the cryogenic dryer, 31, the gas separation unit, 32, the fifth one-way valve, 33, the separation one-way valve, 34, the pure gas storage tank, 35, the recycling valve, 36, the fuel gas supply valve, 37, the second flare gas supply valve, 38, the gas detection transmitter, 39, the bypass valve, 40, the absorption tower, 41, the atomizing spray head, 42, the atomizing pump, 43, the liquid replenishing valve, 44, the absorption liquid supply pipe group, 45, the overflow valve, 46, the overflow tank, 47, the distillation equipment, 48, the third one-way valve. DETAILED DESCRIPTION

[0028] Example:

[0029] like Figures 1 to 6 The flare gas recovery device shown comprises:

[0030] PLC for whole machine control;

[0031] A water seal tank 1, wherein a demister 2 is disposed at the upper inner portion of the water seal tank 1; the lower portion of the water seal tank 1 is connected to a flare gas inlet pipe 4 via a first one-way valve 3;

[0032] The dry gas holder 5, the flare gas inlet pipe 4 is connected to the second one-way valve 6 at the input end of the first one-way valve 3; the second one-way valve 6 is connected to the dry gas holder 5 through the first electric control valve 7; the top of the water seal tank 1 is connected between the second one-way valve 6 and the first electric control valve 7 through the third one-way valve 48;

[0033] Discharge tank 8, the bottom of the water seal tank 1 is connected to the discharge tank 8 through a double valve group 9; the double valve group 9 is connected to the upper part of the water seal tank 1 through a relief valve 10;

[0034] A back-pressure tank 11, wherein the back-pressure tank 11 is connected to the bottom of the discharge tank 8 through a back-pressure valve 12, and the top of the back-pressure tank 11 is connected to the top of the water seal tank 1 through an air supply valve 13, and a first pressure transmitter 14 is provided on the top of the back-pressure tank 11;

[0035] The joint control valve unit includes a safety relief valve 15, a first flare gas supply valve 16 and a second pressure transmitter 17 installed on the top of the water seal tank 1; the output ends of the safety relief valve 15 and the first flare gas supply valve 16 are connected to the flare equipment 18. When the water seal tank 1 is working, the flare gas breaks through the water seal. When the second pressure transmitter 17 detects that the pressure value reaches the set value, the first flare gas supply valve 16 opens and the flare gas is discharged to the flare equipment 18; when the first flare gas supply valve 16 or the second pressure transmitter 17 fails, or a large displacement occurs to cause the water seal tank 1 to continue to rise, the safety relief valve 15 is directly opened, so that the flare gas can be sent to the flare equipment 18, so that the water seal tank 1 is continuously in a safe operating state.

[0036] The flare gas inlet pipe 4 delivers the flare gas to the water seal tank 1 through the first one-way valve 3, and due to the water seal effect of the water seal tank 1, the flare gas cannot break through the water seal tank 1, and the flare gas is delivered to the dry gas holder 5 through the second one-way valve 6 and the first electric control valve 7; when the flare gas partially penetrates through the water seal of the water seal tank 1, the flare gas with a large flow rate can be synchronously absorbed into the flare gas with a large flow rate during the process of passing through the second one-way valve 6 and the first electric control valve 7, so as to fully recover the flare gas; when a production line failure occurs, resulting in a large displacement state in the flare gas inlet pipe 4 or a failure in the dry gas holder 5, the double valve group 9 acts quickly, and the water seal tank 1 quickly delivers the water seal to the discharge tank 8; at this time, the large displacement of flare gas enters the water seal tank 1 through the flare gas inlet pipe 4, breaks through the water seal of the water seal tank 1 and enters the flare equipment 18, entering the flare Before the torch equipment 18, the flare gas is supplied to the water seal tank 1 through the gas supply valve 13 until the first pressure transmitter 14 monitors the set pressure value, the gas supply valve 13 is closed, the inter-control valve unit is opened, and gas is supplied to the flare equipment 18; when the production line and the dry gas holder 5 are restored, the inter-control valve unit is closed, the back pressure valve 12 is opened, and the high-pressure flare gas in the discharge tank 8 drives the water seal in the discharge tank 8 into the water seal tank 1, and then the valve body above the double valve group 9 is closed, the back pressure valve 12 is closed, and then the gas relief valve 10 is opened to send the flare gas in the discharge tank 8 to the top of the water seal, and the first electric control valve 7 is opened to realize the delivery of the flare gas to the dry gas holder 5; finally, the valve body below the double valve group 9 is closed, and the valve body above the double valve group 9 is opened, so as to discharge the remaining gas to the top of the water seal, and finally the gas relief valve 10 and the valve body above and below the double valve group 9 are closed.

[0037] The output end of the first electric control valve 7 is connected to the acid gas rough absorption unit 19, and the output end of the acid gas rough absorption unit 19 is connected to the acid gas fine absorption unit 20; the output end of the acid gas fine absorption unit 20 is connected to the solid-liquid separator 21, the liquid discharge end of the solid-liquid separator 21 is connected to the liquid storage tank 22, the exhaust end of the solid-liquid separator 21 is connected to the pressurizing valve 23, the pressurizing valve 23 is connected to the compressor 24, the output end of the compressor 24 is connected to the intermediate pressure control tank 26 through the fourth one-way valve 25, and the top of the intermediate pressure control tank 26 is connected to the third pressure transmitter 27 and the deep pressure transmitter 28. Cold pressure control valve 28, the deep cold pressure control valve 28 is connected to the deep cold dryer 30 through the pressure equalizing valve 29; the intermediate pressure control tank 26 and the bottom of the deep cold dryer 30 are connected to the liquid storage tank 22; the exhaust end of the deep cold dryer 30 is connected to the gas separation unit 31, and the output end of the gas separation unit 31 is connected to the dry gas holder 5 through the fifth one-way valve 32; the separation end of the gas separation unit 31 is connected to the pure gas storage tank 34 through the separation one-way valve 33; the pure gas storage tank 34 is connected to the gas application pipeline through the reuse valve 35; the dry gas holder 5 is connected to the fuel gas pipeline network through the fuel gas supply valve 36.

[0038] The flare gas is blocked by the water seal tank 1 and enters the acid gas rough absorption unit 19 through the first electric control valve 7. After the flare gas passes through the acid gas rough absorption, it enters the acid gas fine absorption unit 20 for fine absorption, and is finally sent to the solid-liquid separator 21 for solid-liquid separation. The separated liquid is sent to the liquid storage tank 22 for temporary storage. The separated gas is sent to the compressor 24 through the pressure boosting valve 23. After being pressurized by the compressor 24, the compressed flare gas enters the intermediate pressure control tank 26 through the fourth one-way valve 25. After the intermediate pressure control tank 26 reaches the set pressure, the flare gas is discharged. The torch gas is intermittently supplied to the cryogenic dryer 30 through the cryogenic pressure control valve 28, so that the cryogenic dryer 30 works intermittently, avoiding energy waste of the cryogenic dryer 30; after completing the cryogenic drying, the dry flare gas is sent to the gas separation unit 31 to separate the target gas, and is sent to the pure gas storage tank 34 through the separation one-way valve 33, and the target gas is sent to the gas application pipeline (product line or production line) through the pure gas storage tank 34; the remaining fraction of the flare gas is sent to the dry gas holder 5, and the fuel gas supply valve 36 provides gas fuel to the fuel gas pipeline network.

[0039] The dry gas holder 5 is connected to the flare equipment 18 through the second flare gas supply valve 37. When the air pressure of the dry gas holder 5 reaches the set warning value and the fuel gas supply valve 36 is in a closed state, the second flare gas supply valve 37 is opened to send the gas in the dry gas holder 5 to the flare equipment 18, and the gas is continuously consumed by the flare equipment 18 until the air pressure of the dry gas holder 5 drops to the set safety value; the second flare gas supply valve 37 is closed.

[0040] A gas detection transmitter 38 is connected in series between the cryogenic dryer 30 and the gas separation unit 31. A bypass valve 39 is provided at the output end of the cryogenic dryer 30. The bypass valve 39 is connected in parallel to the input and output ends of the gas separation unit 31. The bypass valve 39 is connected to the fifth one-way valve 32. After the flare gas completes cryogenic drying, the flare gas enters the gas separation unit 31. Before the flare gas enters the gas separation unit 31, the target gas components are monitored by the gas detection transmitter 38. When no target gas components are found, the gas separation unit 31 is bypassed by the bypass valve 39, and the flare gas enters the gas separation unit 31 of the next stage, which can improve the flare gas processing efficiency and extend the working cycle and service life of the gas separation unit 31.

[0041] The acid gas rough absorption unit 19 and the acid gas fine absorption unit 20 both include an absorption tower 40, an atomizing spray head 41 is provided at the upper inner side of the absorption tower 40, and the atomizing spray head 41 is connected to the bottom of the absorption tower 40 through an atomizing pump 42; a liquid replenishing valve 43 is provided at the input end of the atomizing pump 42, and the liquid replenishing valve 43 is connected to a high-position absorption liquid supply pipe group 44; an air inlet flange is provided at the lower part of the absorption tower 40, and an overflow valve 45 is provided at the lower part of the air inlet flange of the absorption tower 40; the overflow valve 45 of the acid gas rough absorption unit 19 is connected to an overflow tank 46; the overflow valve 45 of the acid gas fine absorption unit 20 is connected to the absorption liquid supply pipe group 44. When the acid gas rough absorption unit 19 is working, the flare gas enters the absorption tower 40, and the absorption tower 40 can directly perform acid-base neutralization, or use an absorbent for absorption, such as using ethanolamine as the absorption liquid, spraying the absorption liquid through the atomizing spray head 41, and the absorption liquid contacts the flare gas. The atomizing spray liquid can absorb the large acid fractions in the mixed gas containing hydrocarbons, such as carbon dioxide and sulfides. After the acid gas in the flare gas is absorbed by the acid gas rough absorption unit 19, it enters the acid gas fine absorption unit 20, and the acid gas fine absorption unit 20 performs secondary acid absorption on the flare gas that has completed the first acid absorption. Finally, the absorption liquid is sent to the stripping equipment through the overflow tank 46, and the acid gas absorbed by the absorption tower 40 can be desorbed by stripping through the stripping equipment to recover the acid gas.

[0042] The gas separation units 31 are provided in multiple groups, and the separation objects of each group of the gas separation units 31 are different; the exhaust end of the gas separation units 31 of the previous group is connected to the inlet end of the gas separation units 31 of the next group; the flare gas is separated into one or more components through the previous group of gas separation units 31, and the target single component is obtained through distillation; after one or more gases are separated from the flare gas, it is sent to the next group of gas separation units 31, and after multiple separations are completed, the remaining components in the flare gas are sent to the dry gas cabinet 5.

[0043] The gas separation unit 31 is one or more of a pressure swing adsorption device, a temperature swing adsorption device and a membrane separation device; for example, in the flare gas, a single component fraction or a composite fraction is directly separated by the gas separation unit 31, such as separating the composite fraction of hydrogen and methane into a hydrogen fraction and a methane fraction by a pressure swing adsorption fraction. Specifically, the hydrogen and methane fractions enter the pressure swing adsorption device, the hydrogen component that is not easily adsorbed passes through the adsorption tower and is discharged from the pressure swing adsorption device (pressure swing adsorption tower), and the gas components such as methane that are easily adsorbed are retained in the adsorption tower.

[0044] The output end of the separation check valve 33 is connected to the distillation equipment 47, and the exhaust end of the waste gas of the distillation equipment 47 is connected to the dry gas holder 5; the distillation end of the distillation equipment 47 is connected to the pure gas storage tank 34; when working, the flare gas is sent to the gas separation unit 31, and the high-value target fraction is separated by the gas separation unit 31, such as one or more of hydrogen, ethylene, methane, aromatic hydrocarbons, acetaldehyde and catalytic materials are separated respectively, and the target fraction is sent to the distillation equipment 47, and the target fraction is enriched again by the distillation equipment 47, and the waste gas generated in the distillation process is sent to the dry gas holder 5; the enriched target fraction is sent to the pure gas storage tank 34, waiting for application in the product line or production line.

[0045] The above embodiments are only preferred implementations of the present invention, so any equivalent changes or modifications made according to the structures, features and principles described in the scope of application of the present invention are included in the scope of application of the present invention.

Claims

1. A flare gas recovery device, characterized in that: include: PLC for whole machine control; A water seal tank, wherein a demister is arranged at the upper inner portion of the water seal tank; the lower portion of the water seal tank is connected to the flare gas inlet pipe via a first one-way valve; Dry gas holder, the flare gas inlet pipe is connected to a second one-way valve at the input end of the first one-way valve; the second one-way valve is connected to the dry gas holder through a first electric control valve; the top of the water seal tank is connected between the second one-way valve and the first electric control valve through a third one-way valve; The bottom of the water seal tank is connected to the discharge tank through a double valve group; the double valve group is connected to the upper part of the water seal tank through a relief valve; A back-pressure tank, wherein the back-pressure tank is connected to the bottom of the discharge tank through a back-pressure valve, the top of the back-pressure tank is connected to the top of the water seal tank through an air supply valve, and a first pressure transmitter is provided on the top of the back-pressure tank; The joint control valve unit comprises a safety relief valve installed on the top of the water seal tank, a first flare gas supply valve and a second pressure transmitter; the output ends of the safety relief valve and the first flare gas supply valve are connected to the flare equipment.

2. The flare gas recovery device according to claim 1, characterized in that: The output end of the first electric control valve is connected to the acid gas rough absorption unit, and the output end of the acid gas rough absorption unit is connected to the acid gas fine absorption unit; the output end of the acid gas fine absorption unit is connected to the solid-liquid separator, the discharge end of the solid-liquid separator is connected to the liquid storage tank, the exhaust end of the solid-liquid separator is connected to the pressurizing valve, the pressurizing valve is connected to the compressor, the output end of the compressor is connected to the intermediate pressure control tank through the fourth one-way valve, the top of the intermediate pressure control tank is connected with the third pressure transmitter and the cryogenic pressure control valve, the cryogenic pressure control valve is connected to the cryogenic dryer through the pressure equalizing valve; the bottom of the intermediate pressure control tank and the cryogenic dryer are connected to the liquid storage tank; the exhaust end of the cryogenic dryer is connected to the gas separation unit, and the output end of the gas separation unit is connected to the dry gas holder through the fifth one-way valve; the separation end of the gas separation unit is connected to the pure gas storage tank through the separation one-way valve; the pure gas storage tank is connected to the gas application pipeline through the reuse valve; the dry gas holder is connected to the fuel gas pipeline network through the fuel gas supply valve.

3. The flare gas recovery device according to claim 2, characterized in that: The dry gas holder is connected to the flare equipment via a second flare gas supply valve.

4. The flare gas recovery device according to claim 2, characterized in that: A gas detection transmitter is connected in series between the cryogenic dryer and the gas separation unit. A bypass valve is provided at the output end of the cryogenic dryer. The bypass valve is connected in parallel to the input and output ends of the gas separation unit. The bypass valve is connected to the fifth one-way valve.

5. The flare gas recovery device according to claim 2, characterized in that: The acid gas rough absorption unit and the acid gas fine absorption unit both include an absorption tower, an atomizing spray head is arranged at the upper inner side of the absorption tower, and the atomizing spray head is connected to the bottom of the absorption tower through an atomizing pump; a liquid replenishing valve is arranged at the input end of the atomizing pump, and the liquid replenishing valve is connected to a high-position absorption liquid supply pipe group; an air inlet flange is arranged at the lower part of the absorption tower, and an overflow valve is arranged at the lower part of the air inlet flange of the absorption tower; the overflow valve of the acid gas rough absorption unit is connected to the overflow tank; the overflow valve of the acid gas fine absorption unit is connected to the absorption liquid supply pipe group.

6. The flare gas recovery device according to claim 2, characterized in that: The gas separation units are arranged in multiple groups, and the separation objects of each group of the gas separation units are different; the exhaust end of the gas separation units of the previous group is connected to the intake end of the gas separation units of the next group.

7. The flare gas recovery device according to claim 2 or 6, characterized in that: The gas separation unit is one or more of a pressure swing adsorption device, a temperature swing adsorption device and a membrane separation device.

8. The flare gas recovery device according to claim 2, characterized in that: The output end of the separation check valve is connected to the distillation equipment, the exhaust end of the distillation equipment is connected to the dry gas holder; the distillation end of the distillation equipment is connected to the pure gas storage tank.

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