Flare gas pretreatment and recovery device

Abstract

The utility model belongs to a flare gas pretreatment and recovery device. Comprising a torch combustion device and a plurality of waste gas generation systems, waste gas pipelines of the waste gas generation systems are connected with a waste gas absorbing and recycling unit through a pretreatment unit, the waste gas absorbing and recycling unit is connected with a post-treatment circulating unit, and the post-treatment circulating unit is connected with the waste gas absorbing and recycling unit and the torch combustion device; the device has the characteristics of reasonable structural design, capability of effectively solving the problem of large operation load of a torch combustion device caused by large instantaneous flow and capability of reducing purchase and operation cost when a new project is put into use.

Description

Technical Field

[0001] This utility model belongs to the field of waste gas treatment technology, specifically a flare gas pretreatment and recovery device. Background Technology

[0002] In the complex systems of industrial production, flare gas emissions are a matter of great concern. Flares were originally designed to safely treat waste gases generated during production in emergency situations or specific process requirements, thus achieving environmental friendliness. However, in actual use, flare systems present the following problems: 1. Flare gas emissions are characterized by instantaneous flow rates, which can be enormous; that is, when the flare system is operating normally, a sudden increase in load can occur, affecting its normal operation; 2. Flare systems all have a certain operating load, and when additional projects are needed, it is inevitable to redesign and purchase new flare systems, thus increasing operating costs. Utility Model Content

[0003] To overcome the above deficiencies, this utility model provides a flare gas pretreatment and recovery device to solve the technical problems existing in the prior art.

[0004] The technical solution adopted by this utility model to solve its technical problem is:

[0005] A flare gas pretreatment and recovery device includes a flare combustion device, several waste gas generation systems, waste gas pipelines of the several waste gas generation systems are connected to a waste gas absorption and reuse unit through a pretreatment unit, the waste gas absorption and reuse unit is connected to a post-treatment and recycling unit, and the post-treatment and recycling unit is connected to both the waste gas absorption and reuse unit and the flare combustion device.

[0006] The beneficial effects of this utility model are as follows: This utility model abandons the traditional technical solution of directly connecting the exhaust gas pipeline to the flare combustion device. By setting up a pretreatment unit, an exhaust gas absorption and reuse unit, and a post-treatment circulation unit, it can not only recover and reuse the effective components in the exhaust gas, but also extend the exhaust gas flow to play a buffering role. Furthermore, by setting up an exhaust gas absorption and reuse unit, the amount of exhaust gas entering the flare combustion device is reduced, so that one flare combustion device can treat exhaust gas for multiple exhaust gas generation systems, thereby saving equipment investment.

[0007] Preferably, the waste gas pipeline is equipped with a first pressure sensor; the pretreatment unit includes a first condenser, the waste gas pipeline is connected to a first gas-liquid separator through a first heat exchange pipeline of the first condenser, and the gas phase outlet of the first gas-liquid separator is connected to the gas phase inlet of the absorption tower and the gas phase outlet of the absorption tower in the waste gas absorption and reuse unit, respectively.

[0008] Preferably, the waste gas absorption and reuse unit includes an absorption tower, with a gas phase inlet in the lower middle part of the absorption tower connected to a gas distributor in the lower part of the absorption tower, a packing layer in the middle of the absorption tower, a spray pipe at the top of the packing layer, and a gas phase outlet at the top of the absorption tower; the bottom of the absorption tower is connected to the spray pipe through a circulating pump and a first tee, and the third end of the first tee is connected to the reuse section.

[0009] Preferably, the post-treatment circulation unit includes a second condenser, the inlet of the first heat exchange pipe of the second condenser is connected to the gas phase outlet of the absorption tower, the outlet of the first heat exchange pipe of the second condenser is connected to a second gas-liquid separator, the gas phase outlet of the second gas-liquid separator is connected to a flare combustion device through a second tee, and the third end of the second tee is connected to the gas phase inlet of the absorption tower through a circulating fan; a second pressure sensor is installed on the pipeline between the gas phase outlet of the second gas-liquid separator and the second tee.

[0010] Preferably, the liquid phase outlets at the bottom of the first gas-liquid separator and the second gas-liquid separator are connected to the recycling section via corresponding pipes.

[0011] Preferably, the third end of the second tee is connected to the inlet of the circulating fan in sequence through the first valve and the third tee; a fourth tee and a second valve are sequentially provided between the first heat exchange pipe of the first condenser and the first gas-liquid separator, and a third valve is provided between the third tee and the fourth tee; the outlet of the circulating fan is connected to the gas phase inlet of the absorption tower through the fourth valve.

[0012] This utility model also includes a demineralized water pipeline, which is connected to the deaerator in sequence through the second heat exchange pipeline of the second condenser and the second heat exchange pipeline of the first condenser.

[0013] Preferably, a fifth valve and a fifth tee are provided between the first tee and the spray pipe, a sixth valve is provided between the third end of the first tee and the reuse section, and the demineralized water pipe is connected to the third end of the fifth tee through a seventh valve.

[0014] Preferably, an eighth valve is provided between the gas phase outlet of the first gas-liquid separator and the gas phase outlet of the absorption tower, and a ninth valve is provided between the second tee and the flare combustion device.

[0015] A flare gas pretreatment and recovery device manufactured according to the above technical solution, by setting a pretreatment unit, can achieve condensation and buffering of waste gas, which not only reduces the processing load of the waste gas absorption and reuse unit, but also effectively solves the problem of large instantaneous flow of flare gas emission; by setting a waste gas absorption and reuse unit, not only can the valuable parts of the waste gas be recovered and reused, but the amount of waste gas entering the flare combustion device can also be reduced, so as to achieve the purpose of one flare combustion device to treat waste gas generated by multiple waste gas generation systems; by setting a post-treatment circulation unit, the waste gas can be further treated, which not only avoids the problem of liquid in the waste gas affecting the operation of the flare combustion device, but also effectively extends the waste gas treatment process, fully recovers the effective components in the waste gas, and has the characteristic of enabling the flare combustion device to operate stably for a long time; this utility model is based on the waste gas generated by the waste gas generation system Based on its characteristics, this invention incorporates a first pressure sensor and a second pressure sensor. The first pressure sensor detects the pressure within the waste gas pipeline in real time, allowing for the selection of different process routes based on pressure conditions. This ensures stable operation of the entire system while preventing overload of the waste gas absorption and reuse unit. The second pressure sensor monitors the condition of the waste gas before it enters the flare combustion device in real time and adjusts the process route based on pressure to achieve stable operation of the flare combustion device. This invention uses data from both the first and second pressure sensors to adjust the amount of waste gas entering the waste gas absorption and reuse unit and the flare combustion device, ensuring stable operation of the entire system. It features a reasonable structural design, effectively addresses the issue of high instantaneous flow rates causing heavy loads on the flare combustion device, and reduces purchase and operating costs when investing in new projects. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of this utility model.

[0018] In the diagram: 1. Flare combustion device; 2. Waste gas generation system; 3. First pressure sensor; 4. First condenser; 5. First gas-liquid separator; 6. Absorption tower; 7. Gas distributor; 8. Packing layer; 9. Spray pipe; 10. Circulating pump; 11. Reuse section; 12. Second condenser; 13. Second gas-liquid separator; 14. Circulating fan; 15. Second pressure sensor; 16. Demineralized water pipe; 17. Deaerator; 18. First tee; 19. Second tee; 20. Third tee; 21. Fourth tee; 22. Fifth tee; 23. First valve; 24. Second valve; 25. Third valve; 26. Fourth valve; 27. Fifth valve; 28. Sixth valve; 29. ​​Seventh valve; 30. Eighth valve; 31. Ninth valve. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0020] The following is in conjunction with the appendix Figure 1This application provides a further detailed description of a flare gas pretreatment and recovery device. The device includes a flare combustion device 1, several waste gas generation systems 2, and waste gas pipelines from the waste gas generation systems 2 connected to a waste gas absorption and reuse unit via a pretreatment unit. The waste gas absorption and reuse unit is connected to a post-treatment circulation unit, which is connected to both the waste gas absorption and reuse unit and the flare combustion device 1. This invention, by incorporating a pretreatment unit, a waste gas absorption and reuse unit, and a post-treatment circulation unit, enables the recovery and reuse of waste gas while reducing the waste gas processing capacity of the flare combustion device 1. Furthermore, by extending the process flow between the waste gas pipelines and the flare combustion device 1, the waste gas is buffered, thus enabling one flare combustion device 1 to process waste gas generated from multiple waste gas generation systems 2. The pretreatment unit in this invention primarily performs preliminary condensation and buffering of the waste gas to reduce the processing load on the waste gas absorption and reuse unit and prevent a large amount of gas phase from entering the waste gas absorption and reuse unit. The characteristics of the exhaust gas absorption and reuse unit are that it cannot operate normally. The exhaust gas absorption and reuse unit is used to recover the effective components in the exhaust gas. It not only reduces the operating costs of other sections, but also reduces the amount of exhaust gas processed by the flare combustion device 1. The post-treatment circulation unit can not only achieve deep condensation and buffering of the gas phase to avoid the problem of incomplete combustion of the flare combustion device 1 caused by liquid in the gas phase and reduce the amount of gas phase processed by the flare combustion device 1, but also extend the gas phase process route when the amount of gas phase is too large. On the basis of achieving stable operation of the flare combustion device 1, it can fully recover and reuse the recyclable components in the gas phase.

[0021] Furthermore, a first pressure sensor 3 is provided on the exhaust gas pipeline; the pretreatment unit includes a first condenser 4, and the exhaust gas pipeline is connected to a first gas-liquid separator 5 through a first heat exchange pipeline of the first condenser 4. The gas phase outlet of the first gas-liquid separator 5 is connected to the gas phase inlet of the absorption tower 6 and the gas phase outlet of the absorption tower 6 in the exhaust gas absorption and reuse unit, respectively. The first pressure sensor 3 described in this invention is used to detect the pressure of the waste gas in the waste gas pipeline in real time, and adjust the process route of the waste gas according to the pressure to ensure the stable operation of the entire system. The first condenser 4 described in this invention can condense easily liquefied gases in the waste gas, thereby reducing the processing load in the subsequent waste gas absorption and reuse unit. Furthermore, it can reduce the activity of gas molecules in the waste gas, preparing for the subsequent absorption. By setting the first gas-liquid separator 5, not only can the liquid condensed in the first condenser 4 be separated into gas and liquid, but the amount of gas absorbed in the waste gas absorption and reuse unit can also be stabilized. At the same time, by connecting the gas phase outlet of the first gas-liquid separator 5 to the gas phase outlet of the absorption tower 6, it can be ensured that when the first gas-liquid separator 5 is over-pressurized, the back pressure of the subsequent flare emission system does not exceed the standard.

[0022] Furthermore, the waste gas absorption and reuse unit includes an absorption tower 6. The lower middle part of the absorption tower 6 is provided with a gas phase inlet connected to a gas distributor 7 in the lower part of the absorption tower 6. The middle part of the absorption tower 6 is provided with a packing layer 8. The top of the packing layer 8 is provided with a spray pipe 9. The top of the absorption tower 6 is provided with a gas phase outlet. The bottom of the absorption tower 6 is connected to the spray pipe 9 through a circulation pump 10 and a first tee 18. The third end of the first tee 18 is connected to the reuse section 11. The absorption tower 6 described in this invention is used to absorb usable components in waste gas. Preferably, there are two packing layers 8, each with a spray pipe 9 at its top. The lower part of the absorption tower 6 contains the absorbent liquid, which can be circulated and sprayed through the spray pipe 9 via a circulation pump 10 or sent to the recycling section 11 for reuse. The gas distributor 7 is located below the absorbent liquid surface in the lower part of the absorption tower 6. The gas distributor 7 ensures uniform distribution of the waste gas and increases the contact area between the defoamer and the absorbent liquid, thereby improving the absorption efficiency of usable components. Furthermore, the unabsorbed gas phase comes into countercurrent contact with the spray liquid flowing downwards, achieving secondary absorption and thus fully absorbing the effective components in the waste gas.

[0023] Furthermore, the post-processing circulation unit includes a second condenser 12. The inlet of the first heat exchange pipe of the second condenser 12 is connected to the gas phase outlet of the absorption tower 6. The outlet of the first heat exchange pipe of the second condenser 12 is connected to the second gas-liquid separator 13. The gas phase outlet of the second gas-liquid separator 13 is connected to the flare combustion device 1 through a second three-way valve 19. The third end of the second three-way valve 19 is connected to the gas phase inlet of the absorption tower 6 through a circulating fan 14. A second pressure sensor 15 is installed on the pipeline between the gas phase outlet of the second gas-liquid separator 13 and the second three-way valve 19. This invention, by setting a second condenser 12, can recover the solvent carried out in the aforementioned process section, which not only reduces the gas phase entering the subsequent process section, but also helps to reduce the liquid in the gas phase; at the same time, it can also reduce the gas temperature at the gas phase outlet of the absorption tower 6, so as to increase the gas rising rate. Furthermore, by setting a second gas-liquid separator 13, the liquid phase from the second condenser 12 can be separated, avoiding the problem of incomplete combustion of the flare combustion device 1 caused by liquid in the gas phase, thereby improving the service life of the flare combustion device 1.

[0024] Furthermore, the liquid phase outlets at the bottom of the first gas-liquid separator 5 and the second gas-liquid separator 13 are respectively connected to the recycling section 11 via corresponding pipes. This configuration enables the effective recovery and reuse of usable components in the waste gas.

[0025] Furthermore, the third end of the second three-way valve 19 is connected to the inlet of the circulating fan 14 via the first valve 23 and the third three-way valve 20 in sequence. This arrangement prevents excessive pressure in the flare combustion device 1 and extends the gas phase process route, enabling effective recovery and reuse of usable components in the gas phase. A fourth three-way valve 21 and a second valve 24 are sequentially provided between the first heat exchange pipe of the first condenser 4 and the first gas-liquid separator 5, and a third valve 25 is provided between the third three-way valve 20 and the fourth three-way valve 21. The outlet of the circulating fan 14 is connected to the gas phase inlet of the absorption tower 6 via the fourth valve 26. This arrangement prevents excessive pressure in the first gas-liquid separator 5, thus avoiding impact on the stable operation of the entire system.

[0026] This invention also includes a demineralized water pipe 16, which is connected to the deaerator 17 via the second heat exchange pipe of the second condenser 12 and the second heat exchange pipe of the first condenser 4. By setting up a heat exchange connection between the demineralized water pipe 16 and the condenser, this invention enables the effective utilization of heat energy in the exhaust gas, thereby saving boiler feedwater energy consumption.

[0027] Furthermore, a fifth valve 27 and a fifth tee 22 are provided between the first tee 18 and the spray pipe 9, and a sixth valve 28 is provided between the third end of the first tee 18 and the reuse section 11. The demineralized water pipe 16 is connected to the third end of the fifth tee 22 through a seventh valve 29. The demineralized water in the demineralized water pipe 16 can not only be used for the recovery and utilization of heat energy, but also as a replenishment liquid for the absorbent.

[0028] Furthermore, an eighth valve 30 is provided between the gas phase outlet of the first gas-liquid separator 5 and the gas phase outlet of the absorption tower 6, and a ninth valve 31 is provided between the second three-way valve 19 and the flare combustion device 1.

[0029] This utility model also provides a method for recycling flare gas pretreatment and recovery devices, which includes the following steps:

[0030] Step 1: The waste gas produced by several waste gas generation systems 2 enters the waste gas pipeline respectively, and the first pressure sensor 3 monitors the pressure of the waste gas in the waste gas pipeline in real time.

[0031] Step 2: When the pressure of the exhaust gas does not exceed the preset threshold, the exhaust gas in the exhaust gas pipeline is condensed through the first heat exchange pipe of the first condenser 4. After condensation, it enters the first gas-liquid separator 5 for buffering and gas-liquid separation. The gas phase after gas-liquid separation enters the gas distributor 7 in the absorption tower 6, so that the gas phase is evenly distributed, bubbles are broken and absorbed. The unabsorbed gas phase rises to the packing layer 8 and comes into countercurrent contact with the absorbent liquid from the spray pipe 9 to achieve full absorption of the usable components in the gas phase.

[0032] Step 3: The unabsorbed gas phase in the absorption tower 6 enters the first heat exchange pipe of the second condenser 12 for further heat exchange and cooling. After cooling, it enters the second gas-liquid separator 13 for buffering and gas-liquid separation. When the gas phase after gas-liquid separation passes through the second pressure sensor 15, its pressure is detected. When the pressure meets the preset threshold, the gas phase enters the flare combustion device 1 for combustion treatment.

[0033] Step 4: When the pressure of the exhaust gas exceeds the preset threshold, the exhaust gas in the exhaust gas pipeline is condensed through the first heat exchange pipe of the first condenser 4. After condensation, it enters the first gas-liquid separator 5 for buffering and gas-liquid separation. Part of the gas phase after gas-liquid separation enters the absorption tower 6 to absorb the gas, and the other part of the gas phase flows to the gas phase outlet of the absorption tower 6, mixes with the unabsorbed gas phase from the absorption tower 6, and repeats the above step 3.

[0034] Step 5: When the gas phase after gas-liquid separation passes through the second pressure sensor 15, its pressure is detected. When the pressure exceeds the preset threshold, part of the gas phase enters the flare combustion device 1 for combustion treatment, and the other part of the gas phase enters the gas distributor 7 in the absorption tower 6 through the circulating fan 14 for secondary absorption. The gas phase after secondary absorption repeats the above step 3.

[0035] Step 6: When the pressure at the outlet of the first heat exchange pipe of the first condenser 4 in step 2 exceeds the preset threshold, a portion of the material enters the first gas-liquid separator 5 for gas-liquid separation, and the above step 2 is repeated; the other portion of the material enters the gas distributor 7 in the absorption tower 6 through the circulating fan 14 for absorption, and the above step 3 is repeated.

[0036] Step 7: The demineralized water in the demineralized water pipe 16 enters the deaerator 17 for deoxygenation after passing through the second heat exchange pipe of the second condenser 12 and the second heat exchange pipe of the first condenser 4, and is subsequently used as boiler water.

[0037] Step 8: The absorbent liquid at the bottom of the absorber tower 6 is sent to the recycling section 11 for recycling treatment through the circulation pump 10. The liquid phase in the first gas-liquid separator 5 and the liquid phase in the second gas-liquid separator 13 are respectively sent to the recycling section 11 for recycling treatment.

[0038] Step 9: When the spray pipe 9 needs to be sprayed with absorbent liquid in Step 2, turn on the circulation pump 10 to send the absorbent liquid at the bottom of the absorption tower 6 into the spray pipe 9. When the amount of absorbent liquid at the bottom of the absorption tower 6 is insufficient, the demineralized water in the brine pipe 16 enters the spray pipe 9 through the third end of the seventh valve 29 and the fifth tee 22.

[0039] This invention can treat waste gas generated by several waste gas generation systems 2. The treatment can include treatment when waste gas is generated separately by the waste gas generation systems 2, or treatment when waste gas is generated centrally. In the event of a venting, the waste gas first enters the first condenser 4 for condensation and then enters the first gas-liquid separator 5 for buffering and collection (if the pressure exceeds the safety threshold, it will be vented through the eighth valve 30 to ensure the safety and stability of the system). After gas-liquid separation in the first gas-liquid separator 5, the liquid phase is recovered and reused, and the gas phase is absorbed by the absorption tower 6. Due to the instantaneous increase in pipeline pressure caused by the venting, the pressure is detected by the first pressure sensor 3, and the circulation pump 10 is turned on to allow the absorbent liquid at the bottom of the absorption tower 6 to enter the reuse section 11. At the same time, the seventh valve 29 is turned on to allow the demineralized water in the brine pipeline 16 to enter the spray pipeline 9 to prevent solution saturation and reduce absorption efficiency, thereby maximizing solvent absorption and ensuring that the flare gas is absorbed as much as possible. The absorbed solution is sent to subsequent separation and purification devices for further processing. In this invention, after the waste gas is absorbed, condensed, and separated, the circulating fan 14 is activated based on the pressure at the second pressure sensor 15, allowing the gas to be pressurized and sent to the absorption tower 6 for re-absorption, increasing the system's capacity and further increasing the absorption efficiency. Furthermore, when the pressure at the first pressure sensor 3 is too high, the third valve 25 can be opened to rapidly reduce the gas pressure and send it to the absorption tower 6 for processing, ensuring the stability and safety of the system. Several features described in this invention... The waste gas generation system 2 may include a methylamine unit, an ammonia storage tank area, an ammonia synthesis area, etc., which can recover ammonia, methylamine and other components in the tail gas, treat and absorb them before entering the flare combustion device 1, and then send them to the recycling section 11 (which may be a methylamine unit) for recovery; or the waste gas generation system 2 may include acid gas emissions from the conversion acid gas emission, methanol washing unit acid gas emission, sulfur recovery acid gas emission, and accidentally released acid gas; after being absorbed by methanol, it is slowly sent to the recycling section 11 (which may be a methanol washing unit) for recovery.Furthermore, the preset thresholds of the first pressure sensor 3 and the second pressure sensor 15 described in this utility model can be adjusted according to actual production conditions. For example, if the preset threshold of the first pressure sensor 3 is 0.4 MPa and the preset threshold of the second pressure sensor 15 is 0.3 MPa, and the measured pressure of the first pressure sensor 3 is less than 0.4 MPa and the measured pressure of the second pressure sensor 15 is less than 0.3 MPa, the operation mode of Embodiment 1 can be adopted; if the measured pressure of the first pressure sensor 3 is greater than 0.4 MPa and less than 0.5 MPa and the measured pressure of the second pressure sensor 15 is less than 0.3 MPa, the operation mode of Embodiment 2 can be adopted; if the measured pressure of the first pressure sensor 3 is greater than 0.4 MPa and less than 0.5 MPa and the measured pressure of the second pressure sensor 15 is greater than 0.3 MPa, the operation mode of Embodiment 3 can be adopted; if the measured pressure of the first pressure sensor 3 is greater than 0.5 MPa and the measured pressure of the second pressure sensor 15 is greater than 0.3 MPa, the operation mode of Embodiment 4 can be adopted.

[0040] To explain this utility model in more detail, the present invention will now be further described with reference to the embodiments. Specific embodiments are as follows:

[0041] Example 1

[0042] A flare gas pretreatment and recovery device includes a flare combustion device 1, several waste gas generation systems 2, and waste gas pipelines of the several waste gas generation systems 2 connected to a waste gas absorption and reuse unit via a pretreatment unit. The waste gas absorption and reuse unit is connected to a post-treatment circulation unit, which is connected to both the waste gas absorption and reuse unit and the flare combustion device 1. A first pressure sensor 3 is installed on the waste gas pipelines. The pretreatment unit includes a first condenser 4, and the waste gas pipelines are connected to a first gas-liquid separator 5 via a first heat exchange pipe of the first condenser 4. The gas phase outlet of the first gas-liquid separator 5 is connected to both the gas phase inlet and the gas phase outlet of the absorption tower 6 in the waste gas absorption and reuse unit. The waste gas absorption and reuse unit includes an absorption tower 6. A gas phase inlet is located in the lower middle part of the absorption tower 6 and connected to a gas distributor 7 in the lower part of the absorption tower 6. A packing layer 8 is located in the middle of the absorption tower 6, and a spray pipe 9 is located at the top of the packing layer 8. A gas phase outlet is located at the top of the absorption tower 6. The bottom of the absorption tower 6 is connected to the spray pipe 9 via a circulating pump 10 and a first three-way valve 18. The third end of the first three-way valve 18 is connected to the reuse section 11. The post-treatment circulation unit includes a second condenser 12. The inlet of the first heat exchange pipe of the second condenser 12 is connected to the gas phase outlet of the absorption tower 6, and the outlet of the first heat exchange pipe of the second condenser 12 is connected to a second gas-liquid separator 13. The gas phase outlet of the second gas-liquid separator 13 is connected to a flare combustion device 1 via a second three-way valve 19, and the third end of the second three-way valve 19 is connected to the gas phase inlet of the absorption tower 6 via a circulating fan 14. A second pressure sensor 15 is installed on the pipeline between the gas phase outlet of the second gas-liquid separator 13 and the second three-way valve 19. The liquid phase outlets at the bottom of the first gas-liquid separator 5 and the second gas-liquid separator 13 are respectively connected to the reuse section 11 through corresponding pipes. The third end of the second tee 19 is connected to the inlet of the circulating fan 14 through the first valve 23 and the third tee 20 in sequence; a fourth tee 21 and a second valve 24 are sequentially provided between the first heat exchange pipe of the first condenser 4 and the first gas-liquid separator 5, and a third valve 25 is provided between the third tee 20 and the fourth tee 21; the outlet of the circulating fan 14 is connected to the gas phase inlet of the absorption tower 6 through the fourth valve 26. This utility model also includes a demineralized water pipe 16, which is connected to the deaerator 17 through the second heat exchange pipe of the second condenser 12 and the second heat exchange pipe of the first condenser 4 in sequence. A fifth valve 27 and a fifth tee 22 are provided between the first tee 18 and the spray pipe 9, a sixth valve 28 is provided between the third end of the first tee 18 and the reuse section 11, and the demineralized water pipe 16 is connected to the third end of the fifth tee 22 through the seventh valve 29. An eighth valve 30 is provided between the gas phase outlet of the first gas-liquid separator 5 and the gas phase outlet of the absorption tower 6, and a ninth valve 31 is provided between the second three-way valve 19 and the flare combustion device 1.

[0043] This utility model also provides a method for recycling flare gas pretreatment and recovery devices, which includes the following steps:

[0044] Step 1: The waste gas produced by several waste gas generation systems 2 enters the waste gas pipeline respectively, and the first pressure sensor 3 monitors the pressure of the waste gas in the waste gas pipeline in real time.

[0045] Step 2: When the pressure of the exhaust gas does not exceed the preset threshold, the exhaust gas in the exhaust gas pipeline is condensed through the first heat exchange pipe of the first condenser 4. After condensation, it enters the first gas-liquid separator 5 for buffering and gas-liquid separation. The gas phase after gas-liquid separation enters the gas distributor 7 in the absorption tower 6, so that the gas phase is evenly distributed, bubbles are broken and absorbed. The unabsorbed gas phase rises to the packing layer 8 and comes into countercurrent contact with the absorbent liquid from the spray pipe 9 to achieve full absorption of the usable components in the gas phase.

[0046] Step 3: The unabsorbed gas phase in the absorption tower 6 enters the first heat exchange pipe of the second condenser 12 for further heat exchange and cooling. After cooling, it enters the second gas-liquid separator 13 for buffering and gas-liquid separation. When the gas phase after gas-liquid separation passes through the second pressure sensor 15, its pressure is detected. When the pressure meets the preset threshold, the gas phase enters the flare combustion device 1 for combustion treatment.

[0047] Step 4: The demineralized water in the demineralized water pipe 16 enters the deaerator 17 for deoxygenation after passing through the second heat exchange pipe of the second condenser 12 and the second heat exchange pipe of the first condenser 4, and is subsequently used as boiler water.

[0048] Step 5: The absorbent liquid at the bottom of the absorber tower 6 is sent to the recycling section 11 for recycling treatment through the circulation pump 10. The liquid phase in the first gas-liquid separator 5 and the liquid phase in the second gas-liquid separator 13 are respectively sent to the recycling section 11 for recycling treatment.

[0049] Step 6: When the absorbent liquid needs to be sprayed into the spray pipe 9 in Step 2, turn on the circulation pump 10 to send the absorbent liquid at the bottom of the absorption tower 6 into the spray pipe 9. When the amount of absorbent liquid at the bottom of the absorption tower 6 is insufficient, the demineralized water in the brine pipe 16 enters the spray pipe 9 through the third end of the seventh valve 29 and the fifth tee 22.

[0050] Example 2

[0051] A flare gas pretreatment and recovery device includes a flare combustion device 1, several waste gas generation systems 2, and waste gas pipelines of the several waste gas generation systems 2 connected to a waste gas absorption and reuse unit via a pretreatment unit. The waste gas absorption and reuse unit is connected to a post-treatment circulation unit, which is connected to both the waste gas absorption and reuse unit and the flare combustion device 1. A first pressure sensor 3 is installed on the waste gas pipelines. The pretreatment unit includes a first condenser 4, and the waste gas pipelines are connected to a first gas-liquid separator 5 via a first heat exchange pipe of the first condenser 4. The gas phase outlet of the first gas-liquid separator 5 is connected to both the gas phase inlet and the gas phase outlet of the absorption tower 6 in the waste gas absorption and reuse unit. The waste gas absorption and reuse unit includes an absorption tower 6. A gas phase inlet is located in the lower middle part of the absorption tower 6 and connected to a gas distributor 7 in the lower part of the absorption tower 6. A packing layer 8 is located in the middle of the absorption tower 6, and a spray pipe 9 is located at the top of the packing layer 8. A gas phase outlet is located at the top of the absorption tower 6. The bottom of the absorption tower 6 is connected to the spray pipe 9 via a circulating pump 10 and a first three-way valve 18. The third end of the first three-way valve 18 is connected to the reuse section 11. The post-treatment circulation unit includes a second condenser 12. The inlet of the first heat exchange pipe of the second condenser 12 is connected to the gas phase outlet of the absorption tower 6, and the outlet of the first heat exchange pipe of the second condenser 12 is connected to a second gas-liquid separator 13. The gas phase outlet of the second gas-liquid separator 13 is connected to a flare combustion device 1 via a second three-way valve 19, and the third end of the second three-way valve 19 is connected to the gas phase inlet of the absorption tower 6 via a circulating fan 14. A second pressure sensor 15 is installed on the pipeline between the gas phase outlet of the second gas-liquid separator 13 and the second three-way valve 19. The liquid phase outlets at the bottom of the first gas-liquid separator 5 and the second gas-liquid separator 13 are respectively connected to the reuse section 11 through corresponding pipes. The third end of the second tee 19 is connected to the inlet of the circulating fan 14 through the first valve 23 and the third tee 20 in sequence; a fourth tee 21 and a second valve 24 are sequentially provided between the first heat exchange pipe of the first condenser 4 and the first gas-liquid separator 5, and a third valve 25 is provided between the third tee 20 and the fourth tee 21; the outlet of the circulating fan 14 is connected to the gas phase inlet of the absorption tower 6 through the fourth valve 26. This utility model also includes a demineralized water pipe 16, which is connected to the deaerator 17 through the second heat exchange pipe of the second condenser 12 and the second heat exchange pipe of the first condenser 4 in sequence. A fifth valve 27 and a fifth tee 22 are provided between the first tee 18 and the spray pipe 9, a sixth valve 28 is provided between the third end of the first tee 18 and the reuse section 11, and the demineralized water pipe 16 is connected to the third end of the fifth tee 22 through the seventh valve 29. An eighth valve 30 is provided between the gas phase outlet of the first gas-liquid separator 5 and the gas phase outlet of the absorption tower 6, and a ninth valve 31 is provided between the second three-way valve 19 and the flare combustion device 1.

[0052] This utility model also provides a method for recycling flare gas pretreatment and recovery devices, which includes the following steps:

[0053] Step 1: The waste gas produced by several waste gas generation systems 2 enters the waste gas pipeline respectively, and the first pressure sensor 3 monitors the pressure of the waste gas in the waste gas pipeline in real time.

[0054] Step 2: When the pressure of the exhaust gas exceeds the preset threshold, the exhaust gas in the exhaust gas pipeline is condensed through the first heat exchange pipe of the first condenser 4. After condensation, it enters the first gas-liquid separator 5 for buffering and gas-liquid separation. Part of the gas phase after gas-liquid separation enters the absorption tower 6 for gas absorption, and the other part of the gas phase flows to the gas phase outlet of the absorption tower 6 and mixes with the unabsorbed gas phase from the absorption tower 6. The gas phase after gas-liquid separation enters the gas distributor 7 in the absorption tower 6 to make the gas phase uniformly distributed, defoamed and absorbed. The unabsorbed gas phase rises to the packing layer 8 and comes into countercurrent contact with the absorbent liquid from the spray pipe 9 to achieve full absorption of the usable components in the gas phase.

[0055] Step 3: The mixed gas phase enters the first heat exchange pipe of the second condenser 12 for further heat exchange and cooling. After cooling, it enters the second gas-liquid separator 13 for buffering and gas-liquid separation. When the gas phase after gas-liquid separation passes through the second pressure sensor 15, its pressure is detected. When the pressure meets the preset threshold, the gas phase enters the flare combustion device 1 for combustion treatment.

[0056] Step 4: The demineralized water in the demineralized water pipe 16 enters the deaerator 17 for deoxygenation after passing through the second heat exchange pipe of the second condenser 12 and the second heat exchange pipe of the first condenser 4, and is subsequently used as boiler water.

[0057] Step 5: The absorbent liquid at the bottom of the absorber tower 6 is sent to the recycling section 11 for recycling treatment through the circulation pump 10. The liquid phase in the first gas-liquid separator 5 and the liquid phase in the second gas-liquid separator 13 are respectively sent to the recycling section 11 for recycling treatment.

[0058] Step 6: When the absorbent liquid needs to be sprayed into the spray pipe 9 in Step 2, turn on the circulation pump 10 to send the absorbent liquid at the bottom of the absorption tower 6 into the spray pipe 9. When the amount of absorbent liquid at the bottom of the absorption tower 6 is insufficient, the demineralized water in the brine pipe 16 enters the spray pipe 9 through the third end of the seventh valve 29 and the fifth tee 22.

[0059] Example 3

[0060] A flare gas pretreatment and recovery device includes a flare combustion device 1, several waste gas generation systems 2, and waste gas pipelines of the several waste gas generation systems 2 connected to a waste gas absorption and reuse unit via a pretreatment unit. The waste gas absorption and reuse unit is connected to a post-treatment circulation unit, which is connected to both the waste gas absorption and reuse unit and the flare combustion device 1. A first pressure sensor 3 is installed on the waste gas pipelines. The pretreatment unit includes a first condenser 4, and the waste gas pipelines are connected to a first gas-liquid separator 5 via a first heat exchange pipe of the first condenser 4. The gas phase outlet of the first gas-liquid separator 5 is connected to both the gas phase inlet and the gas phase outlet of the absorption tower 6 in the waste gas absorption and reuse unit. The waste gas absorption and reuse unit includes an absorption tower 6. A gas phase inlet is located in the lower middle part of the absorption tower 6 and connected to a gas distributor 7 in the lower part of the absorption tower 6. A packing layer 8 is located in the middle of the absorption tower 6, and a spray pipe 9 is located at the top of the packing layer 8. A gas phase outlet is located at the top of the absorption tower 6. The bottom of the absorption tower 6 is connected to the spray pipe 9 via a circulating pump 10 and a first three-way valve 18. The third end of the first three-way valve 18 is connected to the reuse section 11. The post-treatment circulation unit includes a second condenser 12. The inlet of the first heat exchange pipe of the second condenser 12 is connected to the gas phase outlet of the absorption tower 6, and the outlet of the first heat exchange pipe of the second condenser 12 is connected to a second gas-liquid separator 13. The gas phase outlet of the second gas-liquid separator 13 is connected to a flare combustion device 1 via a second three-way valve 19, and the third end of the second three-way valve 19 is connected to the gas phase inlet of the absorption tower 6 via a circulating fan 14. A second pressure sensor 15 is installed on the pipeline between the gas phase outlet of the second gas-liquid separator 13 and the second three-way valve 19. The liquid phase outlets at the bottom of the first gas-liquid separator 5 and the second gas-liquid separator 13 are respectively connected to the reuse section 11 through corresponding pipes. The third end of the second tee 19 is connected to the inlet of the circulating fan 14 through the first valve 23 and the third tee 20 in sequence; a fourth tee 21 and a second valve 24 are sequentially provided between the first heat exchange pipe of the first condenser 4 and the first gas-liquid separator 5, and a third valve 25 is provided between the third tee 20 and the fourth tee 21; the outlet of the circulating fan 14 is connected to the gas phase inlet of the absorption tower 6 through the fourth valve 26. This utility model also includes a demineralized water pipe 16, which is connected to the deaerator 17 through the second heat exchange pipe of the second condenser 12 and the second heat exchange pipe of the first condenser 4 in sequence. A fifth valve 27 and a fifth tee 22 are provided between the first tee 18 and the spray pipe 9, a sixth valve 28 is provided between the third end of the first tee 18 and the reuse section 11, and the demineralized water pipe 16 is connected to the third end of the fifth tee 22 through the seventh valve 29. An eighth valve 30 is provided between the gas phase outlet of the first gas-liquid separator 5 and the gas phase outlet of the absorption tower 6, and a ninth valve 31 is provided between the second three-way valve 19 and the flare combustion device 1.

[0061] This utility model also provides a method for recycling flare gas pretreatment and recovery devices, which includes the following steps:

[0062] Step 1: The waste gas produced by several waste gas generation systems 2 enters the waste gas pipeline respectively, and the first pressure sensor 3 monitors the pressure of the waste gas in the waste gas pipeline in real time.

[0063] Step 2: When the pressure of the exhaust gas exceeds the preset threshold, the exhaust gas in the exhaust gas pipeline is condensed through the first heat exchange pipe of the first condenser 4. After condensation, it enters the first gas-liquid separator 5 for buffering and gas-liquid separation. Part of the gas phase after gas-liquid separation enters the absorption tower 6 for gas absorption, and the other part of the gas phase flows to the gas phase outlet of the absorption tower 6 and mixes with the unabsorbed gas phase from the absorption tower 6. The gas phase after gas-liquid separation enters the gas distributor 7 in the absorption tower 6 to make the gas phase uniformly distributed, defoamed and absorbed. The unabsorbed gas phase rises to the packing layer 8 and comes into countercurrent contact with the absorbent liquid from the spray pipe 9 to achieve full absorption of the usable components in the gas phase.

[0064] Step 3: The mixed gas phase enters the first heat exchange pipe of the second condenser 12 for further heat exchange and cooling. After cooling, it enters the second gas-liquid separator 13 for buffering and gas-liquid separation. The pressure of the gas phase after gas-liquid separation is detected when it passes through the second pressure sensor 15.

[0065] Step 4: When the gas phase after gas-liquid separation passes through the second pressure sensor 15, its pressure is detected. When the pressure exceeds the preset threshold, part of the gas phase enters the flare combustion device 1 for combustion treatment, and the other part of the gas phase enters the gas distributor 7 in the absorption tower 6 through the circulating fan 14 for secondary absorption. The gas phase after secondary absorption repeats the above step 3.

[0066] Step 5: The demineralized water in the demineralized water pipe 16 enters the deaerator 17 for deoxygenation after passing through the second heat exchange pipe of the second condenser 12 and the second heat exchange pipe of the first condenser 4, and is subsequently used as boiler water.

[0067] Step 6: The absorbent liquid at the bottom of the absorber tower 6 is sent to the recycling section 11 for recycling treatment through the circulation pump 10. The liquid phase in the first gas-liquid separator 5 and the liquid phase in the second gas-liquid separator 13 are respectively sent to the recycling section 11 for recycling treatment.

[0068] Step 7: When the spray pipe 9 needs to be sprayed with absorbent liquid in Step 2, turn on the circulation pump 10 to send the absorbent liquid at the bottom of the absorption tower 6 into the spray pipe 9. When the amount of absorbent liquid at the bottom of the absorption tower 6 is insufficient, the demineralized water in the brine pipe 16 enters the spray pipe 9 through the third end of the seventh valve 29 and the fifth tee 22.

[0069] Example 4

[0070] A flare gas pretreatment and recovery device includes a flare combustion device 1, several waste gas generation systems 2, and waste gas pipelines of the several waste gas generation systems 2 connected to a waste gas absorption and reuse unit via a pretreatment unit. The waste gas absorption and reuse unit is connected to a post-treatment circulation unit, which is connected to both the waste gas absorption and reuse unit and the flare combustion device 1. A first pressure sensor 3 is installed on the waste gas pipelines. The pretreatment unit includes a first condenser 4, and the waste gas pipelines are connected to a first gas-liquid separator 5 via a first heat exchange pipe of the first condenser 4. The gas phase outlet of the first gas-liquid separator 5 is connected to both the gas phase inlet and the gas phase outlet of the absorption tower 6 in the waste gas absorption and reuse unit. The waste gas absorption and reuse unit includes an absorption tower 6. A gas phase inlet is located in the lower middle part of the absorption tower 6 and connected to a gas distributor 7 in the lower part of the absorption tower 6. A packing layer 8 is located in the middle of the absorption tower 6, and a spray pipe 9 is located at the top of the packing layer 8. A gas phase outlet is located at the top of the absorption tower 6. The bottom of the absorption tower 6 is connected to the spray pipe 9 via a circulating pump 10 and a first three-way valve 18. The third end of the first three-way valve 18 is connected to the reuse section 11. The post-treatment circulation unit includes a second condenser 12. The inlet of the first heat exchange pipe of the second condenser 12 is connected to the gas phase outlet of the absorption tower 6, and the outlet of the first heat exchange pipe of the second condenser 12 is connected to a second gas-liquid separator 13. The gas phase outlet of the second gas-liquid separator 13 is connected to a flare combustion device 1 via a second three-way valve 19, and the third end of the second three-way valve 19 is connected to the gas phase inlet of the absorption tower 6 via a circulating fan 14. A second pressure sensor 15 is installed on the pipeline between the gas phase outlet of the second gas-liquid separator 13 and the second three-way valve 19. The liquid phase outlets at the bottom of the first gas-liquid separator 5 and the second gas-liquid separator 13 are respectively connected to the reuse section 11 through corresponding pipes. The third end of the second tee 19 is connected to the inlet of the circulating fan 14 through the first valve 23 and the third tee 20 in sequence; a fourth tee 21 and a second valve 24 are sequentially provided between the first heat exchange pipe of the first condenser 4 and the first gas-liquid separator 5, and a third valve 25 is provided between the third tee 20 and the fourth tee 21; the outlet of the circulating fan 14 is connected to the gas phase inlet of the absorption tower 6 through the fourth valve 26. This utility model also includes a demineralized water pipe 16, which is connected to the deaerator 17 through the second heat exchange pipe of the second condenser 12 and the second heat exchange pipe of the first condenser 4 in sequence. A fifth valve 27 and a fifth tee 22 are provided between the first tee 18 and the spray pipe 9, a sixth valve 28 is provided between the third end of the first tee 18 and the reuse section 11, and the demineralized water pipe 16 is connected to the third end of the fifth tee 22 through the seventh valve 29. An eighth valve 30 is provided between the gas phase outlet of the first gas-liquid separator 5 and the gas phase outlet of the absorption tower 6, and a ninth valve 31 is provided between the second three-way valve 19 and the flare combustion device 1.

[0071] This utility model also provides a method for recycling flare gas pretreatment and recovery devices, which includes the following steps:

[0072] Step 1: The waste gas produced by several waste gas generation systems 2 enters the waste gas pipeline respectively, and the first pressure sensor 3 monitors the pressure of the waste gas in the waste gas pipeline in real time.

[0073] Step 2: When the pressure of the exhaust gas exceeds the preset threshold, the exhaust gas in the exhaust gas pipeline is condensed through the first heat exchange pipe of the first condenser 4. After condensation, part of the material enters the first gas-liquid separator 5 for gas-liquid separation, and the other part of the material enters the gas distributor 7 in the absorption tower 6 through the circulating fan 14 for absorption. The material that enters the first gas-liquid separator 5 for buffering and gas-liquid separation, the other part of the material and part of the gas phase after gas-liquid separation enter the absorption tower 6 for gas absorption, and the other part of the gas phase flows to the gas phase outlet of the absorption tower 6 and mixes with the unabsorbed gas phase from the absorption tower 6. The absorption process is as follows: the gas phase enters the gas distributor 7 in the absorption tower 6, so that the gas phase is evenly distributed, bubble-breaking and absorbed. The unabsorbed gas phase rises to the packing layer 8 and comes into countercurrent contact with the absorbent liquid from the spray pipe 9 to achieve full absorption of the usable components in the gas phase.

[0074] Step 3: The mixed gas phase enters the first heat exchange pipe of the second condenser 12 for further heat exchange and cooling. After cooling, it enters the second gas-liquid separator 13 for buffering and gas-liquid separation. The pressure of the gas phase after gas-liquid separation is detected when it passes through the second pressure sensor 15.

[0075] Step 4: When the gas phase after gas-liquid separation passes through the second pressure sensor 15, its pressure is detected. When the pressure exceeds the preset threshold, part of the gas phase enters the flare combustion device 1 for combustion treatment, and the other part of the gas phase enters the gas distributor 7 in the absorption tower 6 through the circulating fan 14 for secondary absorption. The gas phase after secondary absorption repeats the above step 3.

[0076] Step 5: The demineralized water in the demineralized water pipe 16 enters the deaerator 17 for deoxygenation after passing through the second heat exchange pipe of the second condenser 12 and the second heat exchange pipe of the first condenser 4, and is subsequently used as boiler water.

[0077] Step 6: The absorbent liquid at the bottom of the absorber tower 6 is sent to the recycling section 11 for recycling treatment through the circulation pump 10. The liquid phase in the first gas-liquid separator 5 and the liquid phase in the second gas-liquid separator 13 are respectively sent to the recycling section 11 for recycling treatment.

[0078] Step 7: When the spray pipe 9 needs to be sprayed with absorbent liquid in Step 2, turn on the circulation pump 10 to send the absorbent liquid at the bottom of the absorption tower 6 into the spray pipe 9. When the amount of absorbent liquid at the bottom of the absorption tower 6 is insufficient, the demineralized water in the brine pipe 16 enters the spray pipe 9 through the third end of the seventh valve 29 and the fifth tee 22.

[0079] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model.

Claims

1. A flare gas pre-treatment recovery device comprising a flare combustion device (1), characterized in that: Several waste gas generation systems (2), the waste gas pipelines of several waste gas generation systems (2) are connected to the waste gas absorption and reuse unit through the pretreatment unit, the waste gas absorption and reuse unit is connected to the post-treatment circulation unit, and the post-treatment circulation unit is connected to the waste gas absorption and reuse unit and the flare combustion device (1) respectively. The exhaust gas pipeline is equipped with a first pressure sensor (3); The pretreatment unit includes a first condenser (4), and the exhaust gas pipeline is connected to the first gas-liquid separator (5) through the first heat exchange pipeline of the first condenser (4). The gas phase outlet of the first gas-liquid separator (5) is connected to the gas phase inlet of the absorption tower (6) and the gas phase outlet of the absorption tower (6) in the exhaust gas absorption and reuse unit, respectively. The waste gas absorption and reuse unit includes an absorption tower (6), a gas phase inlet in the middle and lower part of the absorption tower (6) is connected to a gas distributor (7) in the lower part of the absorption tower (6), a packing layer (8) in the middle part of the absorption tower (6), a spray pipe (9) at the top of the packing layer (8), and a gas phase outlet at the top of the absorption tower (6); the bottom of the absorption tower (6) is connected to the spray pipe (9) through a circulating pump (10) and a first tee (18), and the third end of the first tee (18) is connected to the reuse section (11).

2. The flare gas pretreatment and recovery unit of claim 1, wherein: The post-processing circulation unit includes a second condenser (12), the inlet of the first heat exchange pipe of the second condenser (12) is connected to the gas phase outlet of the absorption tower (6), the outlet of the first heat exchange pipe of the second condenser (12) is connected to the second gas-liquid separator (13), the gas phase outlet of the second gas-liquid separator (13) is connected to the flare combustion device (1) through the second tee (19), and the third end of the second tee (19) is connected to the gas phase inlet of the absorption tower (6) through the circulating fan (14); a second pressure sensor (15) is provided on the pipeline between the gas phase outlet of the second gas-liquid separator (13) and the second tee (19).

3. The flare gas pretreatment and recovery unit of claim 2, wherein: The liquid phase outlets at the bottom of the first gas-liquid separator (5) and the second gas-liquid separator (13) are respectively connected to the recycling section (11) through corresponding pipes.

4. The flare gas pretreatment and recovery unit of claim 2, wherein: The third end of the second tee (19) is connected to the inlet of the circulating fan (14) in sequence through the first valve (23) and the third tee (20); A fourth tee (21) and a second valve (24) are sequentially provided between the first heat exchange pipe of the first condenser (4) and the first gas-liquid separator (5), and a third valve (25) is provided between the third tee (20) and the fourth tee (21). The outlet of the circulating fan (14) is connected to the gas phase inlet of the absorption tower (6) through the fourth valve (26).

5. A flare gas pretreatment and recovery device according to claim 2, characterized in that: It also includes a demineralized water pipe (16), which is connected to the deaerator (17) in sequence through the second heat exchange pipe of the second condenser (12) and the second heat exchange pipe of the first condenser (4).

6. The flare gas pretreatment and recovery unit of claim 5, wherein: A fifth valve (27) and a fifth tee (22) are provided between the first tee (18) and the spray pipe (9). A sixth valve (28) is provided between the third end of the first tee (18) and the reuse section (11). The demineralized water pipe (16) is connected to the third end of the fifth tee (22) through the seventh valve (29).

7. The flare gas pretreatment and recovery unit of claim 2, wherein: An eighth valve (30) is provided between the gas phase outlet of the first gas-liquid separator (5) and the gas phase outlet of the absorption tower (6), and a ninth valve (31) is provided between the second tee (19) and the flare combustion device (1).

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