Anaerobic methane simultaneous desulfurization and decarburization process for kitchen waste

Abstract

The application discloses a kind of kitchen garbage anaerobic methane synchronous desulfurization and decarburization processes, it is related to the field of kitchen garbage anaerobic fermentation, it includes pretreatment system, and the waste gas generated after processing is sent to odor treatment system;Anaerobic system, with pretreatment system for anaerobic fermentation;Biogas synchronous purification purification system, with anaerobic system to the biogas generated by anaerobic system is purified and desulfurized, decarburized and purified;BNG prepared in biogas synchronous purification purification system is sent to downstream process device, and the analysis gas generated is sent to odor treatment system for further processing;Rich liquid generated in biogas synchronous purification purification system is sent to solution regeneration system, and the poor liquid of solution regeneration system is sent back to biogas synchronous purification purification system;The application shortens process flow, and biogas purification desulfurization, decarburization and purification are combined into one process section to complete, so as to save investment, reduce floor area, reduce operating cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of anaerobic fermentation of kitchen waste, and particularly relates to a process for simultaneous desulfurization and decarburization of kitchen waste by anaerobic biogas. BACKGROUND

[0002] Household kitchen waste, kitchen waste and fruit and vegetable waste are collectively referred to as kitchen waste.

[0003] Anaerobic digestion technology is the main way of kitchen waste resource utilization, and the produced biogas (BOG) has the following characteristics:

[0004] (1) The main components of biogas are methane (CH4: 50%~65%), carbon dioxide (CO2: 35%~50%), and hydrogen sulfide (H2S: 1000~3000ppmv), etc. H2S is a toxic and harmful gas, and has corrosive properties. The presence of a large amount of CO2 results in low calorific value and low Wobbe number of biogas, which reduces the combustion performance of biogas. The presence of CO2, H2S and trace amounts of other impurities limits the utilization of biogas.

[0005] (2) The pressure of biogas itself is 0-3kPa, and it is difficult to transport over long distances. It is generally used locally.

[0006] The above characteristics limit the high-value utilization of biogas. After purification and purification, the impurities in the biogas are removed to prepare biological natural gas (BNG) that meets the gas quality standards of "Natural Gas" and "Vehicle Compressed Natural Gas". BNG is a standardized commodity with strong applicability and improved economic value.

[0007] After biogas purification to BNG, the sales channels are more diversified. BNG can be adjusted to the appropriate pressure and injected into the municipal gas pipeline network for sale. BNG can also be pressurized and supplied to gas stations and gas users through CNG long tube trailers. The pressure of the gas pipeline network branch network is generally not higher than 0.4MPa, the main network is about 4MPa, and the CNG mother station pressure is 20-25MPa.

[0008] Currently, biogas purification and purification are generally completed in two process sections. First, H2S and other impurities are removed to achieve purified biogas, and then CO2 is removed to achieve purification. The final product gas (BNG) meets the requirements of relevant standards. Biogas purification is generally achieved under normal pressure of 0-30kPa, and biogas purification is generally completed under pressure of 0.6~2.0MPa. The pressure of BNG is basically the same as the purification pressure. Finally, according to the pressure requirement of the gas end, the BNG is input into the gas end after being depressurized or pressurized. The waste gas generated by the purification and purification system is generally connected to the full-plant odor treatment system to meet the requirements of standard emission.

[0009] The current process has the following disadvantages:

[0010] (1) Purification, purification in two steps, complex process, many process equipment, high investment and operation cost.

[0011] (2) The pressure is also adjusted in two steps. First, the pressure is increased before purification, and finally, the BNG is depressurized or pressurized to meet the pressure demand of the use end. The CO2 and CH4 in the biogas need to be pressurized simultaneously during the first pressurization, while the CO2 after purification is released at normal pressure, resulting in energy waste. In addition, the pressure of the BNG after purification in some projects is higher than that of the use end, such as BNG pressure 2.0MPa, which needs to be reduced to 0.4MPa for delivery to the municipal gas pipeline network, also causing energy waste.

[0012] Since purification, purification and pressure adjustment are completed in different process sections or equipment, the entire purification and purification system process is complex, the equipment is numerous, the overall investment cost of the system is high, and the land occupation is large. And because the purification process section operates under pressure, the system has many special equipment such as pressure vessels and safety valves, which increases the operation risk and operation cost. SUMMARY

[0013] The main technical problem to be solved by the present application is to provide an anaerobic biogas simultaneous desulfurization and decarburization process for kitchen waste, which can solve the problems mentioned in the background art.

[0014] In order to solve the above-mentioned main technical problems, the following technical solutions are adopted:

[0015] An anaerobic biogas simultaneous desulfurization and decarburization process for kitchen waste, comprising:

[0016] A pretreatment system for pretreating kitchen waste, the waste gas generated after pretreatment is sent to an odor treatment system for further treatment and emission after reaching the standard;

[0017] An anaerobic system in communication with the pretreatment system for receiving pretreated kitchen waste and performing anaerobic fermentation;

[0018] A biogas simultaneous purification and purification system in communication with the anaerobic system to purify and decarbonize the biogas generated by the anaerobic system; the BNG prepared by the biogas simultaneous purification and purification system is sent to a downstream process device, the resolved gas is sent to an odor treatment system for further treatment and emission after reaching the standard; the rich liquid generated in the biogas simultaneous purification and purification system is sent to a solution regeneration system, and the lean liquid of the solution regeneration system is sent back to the biogas simultaneous purification and purification system.

[0019] Preferably, the biogas generated by the anaerobic system is pressurized by a biogas pressurization device and then sent to the biogas simultaneous purification and purification system.

[0020] Preferably, the BNG produced by the biogas simultaneous purification and purification system is pressurized by a BNG pressurizing device and then sent to downstream process devices.

[0021] Preferably, the biogas simultaneous purification and purification system comprises an absorption tower and a BNG heat exchanger; the BNG produced by the absorption tower is communicated with the shell side of the BNG heat exchanger; the rich liquid at the bottom of the absorption tower is communicated with a solution regeneration system by a rich liquid pump.

[0022] Preferably, when the biogas is in normal pressure state, the solution regeneration system comprises a lean liquid-rich liquid heat exchanger, a rich liquid heat exchanger, a lean liquid heat exchanger, a desorption gas heat exchanger, a regeneration tower, a reboiler and a lean liquid pump; the rich liquid heat exchanger, the lean liquid heat exchanger, the desorption gas heat exchanger and the reboiler are all shell-and-tube heat exchangers; the outlet of the rich liquid pump is sequentially communicated with the shell side of the lean liquid-rich liquid heat exchanger, the shell side of the rich liquid heat exchanger and the rich liquid inlet of the regeneration tower; the desorption gas outlet at the top of the regeneration tower is sequentially communicated with the shell side of the desorption gas heat exchanger and an odor treatment system; the outlet at the bottom of the regeneration tower is sequentially communicated with the shell side of the reboiler, the tube side of the lean liquid-rich liquid heat exchanger, the lean liquid pump and the shell side of the lean liquid heat exchanger and then returned to the absorption tower.

[0023] Further, when the biogas is in high pressure state, the flash gas produced by the solution regeneration system is returned to the gas inlet of the biogas pressurizing device.

[0024] Preferably, when the biogas is in high pressure state, the solution regeneration system comprises a rich liquid heat exchanger, a flash gas heat exchanger, a lean liquid heat exchanger, a lean liquid-semi-lean liquid heat exchanger, a semi-lean liquid heat exchanger, a desorption gas heat exchanger, a flash tower, a regeneration tower, a reboiler, a lean liquid pump and a semi-lean liquid pump; the rich liquid heat exchanger, the flash gas heat exchanger, the lean liquid heat exchanger, the lean liquid-semi-lean liquid heat exchanger, the semi-lean liquid heat exchanger and the desorption gas heat exchanger are all shell-and-tube heat exchangers; the outlet of the rich liquid pump is communicated with the shell side of the rich liquid heat exchanger and then with the rich liquid inlet of the flash tower; the semi-lean liquid outlet at the bottom of the flash tower is sequentially communicated with the semi-lean liquid pump, the shell side of the lean liquid-semi-lean liquid heat exchanger, the shell side of the semi-lean liquid heat exchanger and the semi-lean liquid inlet of the regeneration tower; the flash gas outlet at the top of the flash tower is communicated with the shell side of the flash gas heat exchanger and then returned to the gas inlet of the biogas pressurizing device; the desorption gas outlet at the top of the regeneration tower is sequentially communicated with the shell side of the desorption gas heat exchanger and the odor treatment system; the lean liquid outlet at the bottom of the regeneration tower is sequentially communicated with the shell side of the reboiler, the tube side of the lean liquid-semi-lean liquid heat exchanger, the lean liquid pump, the shell side of the lean liquid heat exchanger and then returned to the absorption tower and the upper part of the flash tower.

[0025] Preferably, the absorption liquid of the absorption tower is an alcohol amine solution; the operation temperature of the absorption tower is 60-80℃; the number of the packing layers of the absorption tower is greater than or equal to the number of the lean liquid inlets.

[0026] Preferably, the regeneration tower is provided with at least one layer of packing; the operation pressure of the regeneration tower is 0.2±0.1 MPa, and the operation temperature is 120±5℃.

[0027] Preferably, the flash tower is provided with at least one layer of packing; the packing of the flash tower is structured packing or random packing; the operation pressure of the flash tower is 0.08±0.01 MPa, and the operation temperature is 90±5℃.

[0028] Compared with the prior art, the application applied to the simultaneous desulfurization and decarburization of kitchen waste anaerobic biogas has the following advantages:

[0029] (1) The process flow is shortened, and the biogas purification, desulfurization and decarburization purification are combined into one process section to complete the two-step process, thereby saving investment, reducing the occupied area and reducing the operation cost.

[0030] (2) The normal pressure operation or pressure operation can be selected according to the specific project condition; if the normal pressure operation is selected, the special equipment such as the booster equipment and the pressure container in the system is reduced, the operation cost and the operation risk are reduced, and the energy waste caused by the CO2 boosting is avoided; if the pressure operation is selected, the biogas is directly boosted to the required pressure of the BNG receiving end (mainly the municipal pipe network), and the energy waste caused by the BNG pressure reduction is avoided.

[0031] (3) The resolved gas (mainly CO2 and H2S) after the purification enters the full-plant deodorization system, and the same as the original process, since the resolved gas amount is far less than the full-plant odor treatment amount, the resolved gas is integrated into the full-plant deodorization system, thereby reducing the operation cost and almost not increasing the investment. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical scheme of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0033] Figure 1 Process flow framework diagram for biogas in normal pressure state;

[0034] Figure 2 Process diagram for biogas in normal pressure state;

[0035] Figure 3 Process flow framework diagram for biogas in high pressure state;

[0036] Figure 4 Process diagram for biogas in high pressure state.

[0037] In the figure: 100 is a biogas synchronous purification and purification system, 200 is a solution regeneration system;

[0038] 1 is an absorption tower, 2 is a flash tower, and 3 is a regeneration tower;

[0039] 4 is a rich liquid pump, 5 is a semi-lean liquid pump, and 6 is a lean liquid pump;

[0040] 11 is a BNG heat exchanger, 12 is a flash gas heat exchanger, 13 is a desorption gas heat exchanger, 14 is a rich liquid heat exchanger, 15 is a reboiler, 16 is a lean liquid heat exchanger, 17 is a lean liquid-rich liquid heat exchanger, 18 is a lean liquid-semi-lean liquid heat exchanger, and 19 is a semi-lean liquid heat exchanger. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application. In addition, all the connection relationships mentioned in the text do not mean that the components are directly connected, but that a better connection structure can be formed by adding or reducing connecting auxiliary parts according to the specific implementation situation.

[0042] Please refer to Figure 1 As shown in the figure, a kitchen waste anaerobic biogas synchronous desulfurization and decarburization process includes a pretreatment system, an anaerobic system, a biogas synchronous purification and purification system 100, and an odor treatment system.

[0043] The pretreatment system is used for pretreating kitchen waste. The waste gas generated after treatment is sent to the odor treatment system for further treatment. After treatment by the odor treatment system, the gas meets the standard and is then discharged. The odor treatment system refers to the prior art.

[0044] The anaerobic system communicates with the pretreatment system and is used for receiving the pretreated kitchen waste and performing anaerobic fermentation.

[0045] The biogas synchronous purification and purification system 100 communicates with the anaerobic system. The biogas generated by the anaerobic system is sent to the biogas synchronous purification and purification system 100 for purification, desulfurization, and decarburization purification. The BNG (biological natural gas) prepared by the biogas synchronous purification and purification system 100 is sent to downstream process devices, such as a municipal gas pipe or a gas filling station or a gas-using enterprise. The desorption gas generated by the biogas synchronous purification and purification system 100 is sent to the odor treatment system for further treatment and is then discharged after reaching the standard.

[0046] The BNG prepared by the biogas synchronous purification and purification system 100 can be pressurized by a BNG pressurizing device and then sent to a downstream process device. The BNG pressurizing device can be selected or discarded according to actual production needs.

[0047] The biogas produced by the anaerobic system is pressurized by a biogas pressurizing device and then sent to the biogas synchronous purification and purification system 100. The biogas pressurizing device can be selected or discarded according to actual production needs.

[0048] The rich liquid produced in the biogas synchronous purification and purification system 100 is sent to the solution regeneration system 200 for reuse, and the lean liquid of the solution regeneration system 200 is sent back to the biogas synchronous purification and purification system 100 for regeneration.

[0049] Embodiment one,

[0050] When the biogas entering the biogas synchronous purification and purification system 100 is in a normal pressure state (<0.1 MPa), please refer to Figure 2 ,

[0051] The biogas synchronous purification and purification system 100 includes an absorption tower 1 and a BNG heat exchanger 11. The absorption tower 1 is fed in the middle part, and the BNG produced by the absorption tower 1 is communicated with the shell side of the BNG heat exchanger 11. The rich liquid at the bottom of the absorption tower 1 is communicated with the solution regeneration system 200 through a rich liquid pump 4. The absorption liquid of the absorption tower 1 is an alcohol amine solution. The operating temperature of the absorption tower 1 is 60-80℃. The number of the packing layers of the absorption tower 1 is greater than or equal to the number of the lean liquid inlets. The packing of the absorption tower 1 can be selected as regular packing or random packing.

[0052] The solution regeneration system 200 includes a lean liquid-rich liquid heat exchanger 17, a rich liquid heat exchanger 14, a lean liquid heat exchanger 16, a desorption gas heat exchanger 13, a regeneration tower 3, a reboiler 15, and a lean liquid pump 6. The rich liquid heat exchanger 14, the lean liquid heat exchanger 16, the desorption gas heat exchanger 13, and the reboiler 15 are all tube-shell heat exchangers. The outlet of the rich liquid pump 4 is sequentially communicated with the shell side of the lean liquid-rich liquid heat exchanger 17, the shell side of the rich liquid heat exchanger 14, and the rich liquid inlet of the regeneration tower 3. The desorption gas outlet at the top of the regeneration tower 3 is communicated with the shell side of the desorption gas heat exchanger 13. The desorption gas is cooled by the desorption gas heat exchanger 13 and then enters a stench gas treatment system. The outlet at the bottom of the regeneration tower 3 is sequentially communicated with the shell side of the reboiler 15, the tube side of the lean liquid-rich liquid heat exchanger 17, the lean liquid pump 6, and the shell side of the lean liquid heat exchanger 16, and then returns to the absorption tower 1. The solution at the outlet at the bottom of the regeneration tower 3 is heated by the reboiler 15 to realize regeneration, and then is pressurized by the lean liquid pump 6, cooled by the lean liquid-rich liquid heat exchanger 17 and the lean liquid heat exchanger 16, and then enters the lean liquid inlet at the upper part of the absorption tower 1.

[0053] The regeneration tower 3 has at least one layer of packing, and the packing of the regeneration tower 3 is regular packing or random packing; the operation pressure of the regeneration tower 3 is 0.2±0.1 MPa, and the operation temperature of the regeneration tower 3 is 120±5℃.

[0054] The process of simultaneous desulfurization and decarburization of the biogas under normal pressure is as follows:

[0055] The biogas enters the absorption tower 1, and BNG is prepared after removal of H2S and CO2 by absorption with lean liquid; the prepared BNG is cooled by the BNG heat exchanger 11 and then enters the downstream process device;

[0056] The rich liquid at the bottom of the absorption tower 1 is pressurized by the rich liquid pump 4, heated by the lean liquid-rich liquid heat exchanger 17 and the rich liquid heat exchanger 14, and then enters the regeneration tower 3;

[0057] The resolved gas at the top of the regeneration tower 3 is cooled by the resolved gas heat exchanger 13 and then enters the odor treatment system; the solution at the bottom of the regeneration tower 3 is heated by the reboiler 15 to realize regeneration; the lean liquid is pressurized by the lean liquid pump 6, cooled by the lean liquid-rich liquid heat exchanger 17 and the lean liquid heat exchanger 16, and then enters the absorption tower 1.

[0058] Example two,

[0059] When the biogas entering the biogas simultaneous purification and purification system 100 is in a high-pressure (0.1-4.5 MPa) state, please participate Figures 3-4 as shown,

[0060] The biogas simultaneous purification and purification system 100 includes the absorption tower 1 and the BNG heat exchanger 11; the middle part of the absorption tower 1 is fed, and the BNG produced by the absorption tower 1 communicates with the shell side of the BNG heat exchanger 11; the rich liquid at the bottom of the absorption tower 1 communicates with the solution regeneration system 200 through the rich liquid pump 4; the absorption liquid of the absorption tower 1 is an alcohol amine solution; the operation temperature of the absorption tower 1 is 60-80℃; the number of layers of the packing of the absorption tower 1 is greater than or equal to the number of lean liquid inlets, and the packing of the absorption tower 1 can be selected as regular packing or random packing.

[0061] The solution regeneration system 200 includes the rich liquid heat exchanger 14, the flash gas heat exchanger 12, the lean liquid heat exchanger 16, the lean liquid-semi-lean liquid heat exchanger 18, the semi-lean liquid heat exchanger 19, the resolved gas heat exchanger 13, the flash tower 2, the regeneration tower 3, the reboiler 15, the lean liquid pump 6, and the semi-lean liquid pump 5; the rich liquid heat exchanger 14, the flash gas heat exchanger 12, the lean liquid heat exchanger 16, the lean liquid-semi-lean liquid heat exchanger 18, the semi-lean liquid heat exchanger 19, the resolved gas heat exchanger 13, and the reboiler 15 are all tube-shell heat exchangers; the outlet of the rich liquid pump 4 is connected to the shell side of the rich liquid heat exchanger 14, and then communicates with the rich liquid inlet of the flash tower 2; the flash gas outlet at the top of the flash tower 2 is connected to the shell side of the flash gas heat exchanger 12 and then returns to the gas inlet of the biogas pressurizing device;

[0062] The semi-lean liquid outlet at the bottom of the flash tower 2 is sequentially communicated with a semi-lean liquid pump 5, a lean liquid-semi-lean liquid heat exchanger 18 shell side, a semi-lean liquid heat exchanger 19 shell side, and a semi-lean liquid inlet of a regeneration tower 3; the resolved gas outlet at the top of the regeneration tower 3 is communicated with a resolved gas heat exchanger 13 shell side, and then is sent to an odor treatment system for further treatment after being cooled; the lean liquid outlet at the bottom of the regeneration tower 3 is sequentially communicated with a shell side of a reboiler 15, a tube side of the lean liquid-semi-lean liquid heat exchanger 18, a lean liquid pump 6, and a shell side of a lean liquid heat exchanger 16, and then is returned to the upper part of the absorption tower 1 and the upper part of the flash tower 2.

[0063] The operating pressure of the regeneration tower 3 is 0.2±0.1 MPa, and the operating temperature is 120±5℃; the flash tower 2 is provided with at least one layer of packing, and the regeneration tower 3 is also provided with at least one layer of packing; the packing of the flash tower 2 and the regeneration tower 3 is regular packing or random packing; the operating pressure of the flash tower 2 is 0.08±0.01 MPa, and the operating temperature is 90±5℃.

[0064] The process of simultaneous desulfurization and decarburization of high-pressure biogas is as follows:

[0065] The high-pressure biogas enters the absorption tower 1, and H2S and CO2 are removed by lean liquid absorption to prepare BNG; the prepared BNG is cooled by a BNG heat exchanger 11 and then enters a downstream process device;

[0066] The rich liquid at the bottom of the absorption tower 1 is pressurized by a rich liquid pump 4 and heated by a rich liquid heat exchanger 14 and then enters the flash tower 2; the flash gas at the top of the flash tower 2 is returned to the inlet of a biogas pressurizing device after being cooled by a flash gas heat exchanger 12 and being absorbed by lean liquid;

[0067] The solution at the bottom of the flash tower 2 is pressurized by a semi-lean liquid pump 5, and then is heated by a lean liquid-semi-lean liquid heat exchanger 18 and a semi-lean liquid heat exchanger 19 and then enters the regeneration tower 3;

[0068] The resolved gas at the top of the regeneration tower 3 is cooled by a resolved gas heat exchanger 13 and then is discharged to an odor treatment system; the solution at the bottom of the regeneration tower 3 is heated by a reboiler 15 to realize regeneration; the regenerated lean liquid is pressurized by a lean liquid pump 6, and then is cooled by a lean liquid-semi-lean liquid heat exchanger 18 and a lean liquid heat exchanger 16 and then is returned to the top of the absorption tower 1 and the top of the flash tower 2.

[0069] The process of purifying, desulfurizing, and decarburizing anaerobic biogas of kitchen waste is simultaneously completed in the alcohol amine absorption tower 1, the process flow of preparing BNG from biogas is simplified, investment is saved, the occupied area is reduced, and the operating cost is reduced.

[0070] Meanwhile, according to the specific project, normal pressure operation or pressure operation can be selected, if normal pressure operation, the booster equipment and special equipment such as pressure vessel in the system are reduced, the operation cost and risk are reduced, and the energy waste caused by CO2 boosting is avoided, if pressure operation, the biogas is directly boosted to the required pressure of the BNG receiving end (mainly municipal pipe network), without secondary pressure reduction, and the energy waste caused by BNG pressure reduction is avoided.

[0071] The purified analysis gas (mainly CO2 and H2S) enters the full-plant deodorization system, and the investment and operation cost of the full-plant deodorization system are almost not increased due to the far smaller analysis gas amount than the full-plant odor treatment amount.

[0072] According to the process provided by the present application, the methane yield is higher than 99%, the methane content in the analysis gas is lower than 1%, the reflux flash steam flow of the high-pressure biogas (0.1-4.5 MPa) desulfurization and decarburization is 10%-20% of the original biogas treatment amount, and the H2S concentration in the reflux steam is lower than 20 ppm.

[0073] The above-mentioned embodiments are only preferred embodiments and are not used to limit the present application, although the present application is described in detail with reference to the foregoing embodiments, the technical solutions recorded in the foregoing embodiments can still be modified by those skilled in the art, or some technical features can be replaced equivalently, any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A process for simultaneous desulfurization and decarburization of anaerobic biogas from kitchen waste, characterized in that: The application relates to a kitchen waste treatment system, which comprises the following parts: a pretreatment system for pretreating kitchen waste, wherein waste gas generated after the pretreatment is sent to a stench treatment system for further treatment and emission after reaching the standard; an anaerobic system in communication with the pretreatment system for receiving the pretreated kitchen waste and carrying out anaerobic fermentation; a biogas synchronous purification and purification system in communication with the anaerobic system so as to purify and desulfurize and decarbonize biogas generated by the anaerobic system; the biogas synchronous purification and purification system comprises an absorption tower and a BNG heat exchanger, the absorption liquid of the absorption tower is an alcohol amine solution, the operation temperature of the absorption tower is 60-80 DEG C, the number of the packing layers of the absorption tower is greater than or equal to the number of the lean liquid inlets, and desulfurization and decarbonization are simultaneously completed in a single absorption tower; the middle part of the absorption tower is provided with a feed, the BNG generated by the absorption tower is in communication with the shell side of the BNG heat exchanger, and the rich liquid at the bottom of the absorption tower is in communication with a solution regeneration system through a rich liquid pump; the BNG prepared by the biogas synchronous purification and purification system is sent to a downstream process device, the resolved gas generated is sent to the stench treatment system for further treatment and emission after reaching the standard; the rich liquid generated in the biogas synchronous purification and purification system is sent to the solution regeneration system, and the lean liquid of the solution regeneration system is sent back to the biogas synchronous purification and purification system; when the biogas is in a normal pressure state, the solution regeneration system comprises a lean liquid-rich liquid heat exchanger, a rich liquid heat exchanger, a lean liquid heat exchanger, a resolved gas heat exchanger, a regeneration tower, a reboiler and a lean liquid pump; the rich liquid heat exchanger, the rich liquid heat exchanger, the lean liquid heat exchanger, the resolved gas heat exchanger and the reboiler are all tube-shell heat exchangers; the outlet of the rich liquid pump is in sequence communication with the shell side of the lean liquid-rich liquid heat exchanger, the shell side of the rich liquid heat exchanger and the rich liquid inlet of the regeneration tower; the resolved gas outlet at the top of the regeneration tower is in sequence communication with the shell side of the resolved gas heat exchanger and the stench treatment system; the outlet at the bottom of the regeneration tower is in sequence communication with the shell side of the reboiler, the tube side of the lean liquid-rich liquid heat exchanger, the lean liquid pump and the shell side of the lean liquid heat exchanger and then returns to the absorption tower; the regeneration tower is provided with at least one layer of packing; the operation pressure of the regeneration tower is 0.2+ / -0.1 MPa, and the operation temperature is 120+ / -5 DEG C. When the biogas is in high pressure state, the solution regeneration system comprises a rich liquid heat exchanger, a flash gas heat exchanger, a lean liquid heat exchanger, a lean liquid-semi-lean liquid heat exchanger, a semi-lean liquid heat exchanger, a desorption gas heat exchanger, a flash tower, a regeneration tower, a reboiler, a lean liquid pump, and a semi-lean liquid pump; the rich liquid heat exchanger, the flash gas heat exchanger, the lean liquid heat exchanger, the lean liquid-semi-lean liquid heat exchanger, the semi-lean liquid heat exchanger, the desorption gas heat exchanger, and the reboiler are all shell-and-tube heat exchangers; the outlet of the rich liquid pump is connected to the rich liquid inlet of the flash tower through the shell side of the rich liquid heat exchanger; the semi-lean liquid outlet at the bottom of the flash tower is sequentially connected to the semi-lean liquid pump, the shell side of the lean liquid-semi-lean liquid heat exchanger, the shell side of the semi-lean liquid heat exchanger, and the semi-lean liquid inlet of the regeneration tower; the flash gas outlet at the top of the flash tower is connected to the shell side of the flash gas heat exchanger and returns to the gas inlet of the biogas pressurizing device; the desorption gas outlet at the top of the regeneration tower is sequentially connected to the shell side of the desorption gas heat exchanger and the odor treatment system; the lean liquid outlet at the bottom of the regeneration tower is sequentially connected to the shell side of the reboiler, the tube side of the lean liquid-semi-lean liquid heat exchanger, the lean liquid pump, and the shell side of the lean liquid heat exchanger, and then returns to the upper part of the absorption tower and the flash tower; the flash tower is provided with at least one layer of packing; the packing of the flash tower is regular packing or random packing; the operating pressure of the flash tower is 0.08±0.01 MPa, and the operating temperature is 90±5℃.

2. The process according to claim 1, wherein, The biogas produced by the anaerobic system is pressurized by the biogas pressurizing device and then sent to the biogas synchronous purification and purification system.

3. The process according to claim 1, wherein, The BNG prepared by the biogas synchronous purification and purification system is pressurized by the BNG pressurizing device and then sent to the downstream process device.

4. The process according to claim 1, wherein, When the biogas is in high pressure state, the flash gas produced by the solution regeneration system returns to the gas inlet of the biogas pressurizing device.

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