Anaerobic fermentation internal biogas purification device and use method thereof

Abstract

The invention discloses an anaerobic fermentation internal biogas purification device and a use method, and belongs to the technical field of biogas purification. The device comprises a desulfurization tank filled with a Fe (OH) or NaOH solution; the filter pipe is internally provided with a semi-permeable membrane, the outer side of the filter pipe is fixedly connected with a spiral blade, the spiral blade divides the space between the filter pipe and the desulfurization tank into a spiral air duct, and the spiral air duct is internally provided with a spiral spraying pipe and a heating part for heating a solution; a cooling part is arranged in the water removal tank; the gas inlet driving assembly is arranged between the desulfurization tank and the water removal tank, the gas inlet driving assembly comprises a pressure pipe for introducing biogas, a pressure driving part is arranged in the pressure pipe, and a semiconductor chilling plate is arranged below the pressure pipe. Sulfide in biogas can be effectively removed, the biogas spirally ascends in the desulfurization tank due to the design of the spiral air duct, the contact time of the biogas and a solution is prolonged, and the desulfurization effect is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of biogas purification, and particularly to an anaerobic fermentation internal biogas purification device and a using method thereof. Background Art

[0002] Biogas is a mixed gas mainly composed of methane, colorless and odorless, and prone to explosion. It is mainly formed by the decomposition and transformation of organic substances (such as human and animal feces, straw, sewage, etc.) under an airtight environment by microorganisms. The main components of biogas include methane and carbon dioxide.

[0003] When using biogas as an energy source, the content of hydrogen sulfide needs to be strictly controlled because it has potential hazards to both equipment and the environment. Hydrogen sulfide not only has strong corrosiveness, which can damage gas equipment, pipelines, engines, etc., but also has an impact on health and the environment. Especially its toxicity requires the use of a biogas purification device to purify the hydrogen sulfide contained in biogas during the biogas transportation process. Most of the existing purification devices simply inject it into water for reaction, with a short contact time with water and poor removal effect of hydrogen sulfide, and cannot purify it more quickly and effectively. Summary of the Invention

[0004] The purpose of the present invention is to provide an anaerobic fermentation internal biogas purification device and a using method thereof, which can effectively remove sulfides in biogas. The design of the spiral air duct makes the biogas move spirally upward in the desulfurization tank, prolonging the contact time between the biogas and the Fe(OH)3 or NaOH solution and improving the desulfurization effect, so as to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] An anaerobic fermentation internal biogas purification device, comprising:

[0007] A desulfurization tank internally filled with Fe(OH)3 or NaOH solution;

[0008] A filter tube internally provided with a semi-permeable membrane, the filter tube is fixedly connected inside the desulfurization tank, a spiral blade is fixedly connected to the outside of the filter tube, and the spiral blade divides the space between the filter tube and the desulfurization tank into a spiral air duct for guiding the biogas to be transported spirally from bottom to top. A spiral spray pipe and a heating part for heating the solution are provided inside the spiral air duct;

[0009] A water removal tank, the water removal tank is placed on one side of the desulfurization tank, and a cooling part is arranged inside the water removal tank for removing water from the biogas;

[0010] An intake air driving assembly is disposed between the desulfurization tank and the water removal tank. The intake air driving assembly includes a pressure pipe for introducing biogas. A pressure driving part is provided inside the pressure pipe. A semiconductor refrigeration chip is disposed below the pressure pipe. The heating end of the semiconductor refrigeration chip heats the heating part and its cooling end cools the cooling part;

[0011] When biogas enters the pressure pipe, the internal pressure thereof increases. Under the action of pressure, the pressure driving part drives the flow of the media in the refrigerating part and the heating part. When the pressure in the pressure pipe reaches the preset value, the biogas enters the desulfurization tank through the filter pipe, and the pressure driving part automatically resets.

[0012] Preferably, the bottom of the filter pipe is fixedly connected with an air outlet pipe through a check valve. The bottom of the desulfurization tank is fixedly connected with a water pump. The water inlet end of the water pump communicates with the bottom of the desulfurization tank. The output end of the water pump is fixedly connected with a spiral spray pipe for spraying the solution inside the desulfurization tank along the flowing direction of the spiral air duct.

[0013] Preferably, the pressure driving part includes an air inlet pipe. The top of the pressure pipe is fixedly connected with an air inlet pipe through a check valve. An electromagnetic valve is fixedly connected to the top of the pressure pipe. The air outlet end of the electromagnetic valve is fixedly connected with an air delivery pipe. One end of the air delivery pipe is connected with the filter pipe. A second piston rod is slidably connected inside the pressure pipe. A permanent magnet is fixedly connected to the top of the second piston rod. A magnetic switch is fixedly connected to one side of the bottom of the pressure pipe. The magnetic switch is electrically connected to the electromagnetic valve.

[0014] Preferably, the bottom of the second piston rod is fixedly connected with a lifting rod. The bottom of the lifting rod is fixedly connected with two first piston rods. The two first piston rods are respectively slidably connected to the inner walls of the first negative pressure pipe and the second negative pressure pipe. A spring is fixedly connected to the bottom of the first piston rod.

[0015] Preferably, the heating part includes a heating box fixedly connected to the bottom of the first negative pressure pipe. The heating end of the semiconductor refrigeration chip is connected to the inside of the heating box through a first fin. A heating spiral pipe is fixedly connected inside the heating box and at the bottom of the first negative pressure pipe. One end of the heating spiral pipe is fixedly connected with a heating pipe. The heating pipe is spirally arranged in the desulfurization tank along the spiral air duct. The other end of the heating pipe is connected to the top of the first negative pressure pipe.

[0016] Preferably, the refrigerating part includes a cooling box fixedly connected to the cooling end of the semiconductor refrigeration chip. The inside of the cooling box is connected to the cooling end of the cooling box through a first fin. A cooling spiral pipe is fixedly connected inside the cooling box. One end of the cooling spiral pipe is connected to the bottom of the second negative pressure pipe. The other end of the cooling spiral pipe is fixedly connected with a cooling pipe. The cooling pipe is fixedly connected inside the water removal tank. A plurality of second fins are fixedly connected at equal intervals on the outside of the cooling pipe. The other end of the cooling pipe is connected to the top of the second negative pressure pipe.

[0017] Preferably, a fixing frame is fixedly connected to the tops of the first negative pressure pipe and the second negative pressure pipe. The heating box and the cooling box are both fixedly connected to the bottom of the fixing frame. The cooling spiral pipe and the heating spiral pipe are both fixedly connected to the first fin. The first piston rod is slidably connected to the fixing frame.

[0018] Preferably, a blower for extracting biogas is provided at the top of the water removal tank, and a water collecting pipe is provided at the bottom of the water removal tank.

[0019] The present invention provides another technical solution: a method for using an internal biogas purification device for anaerobic fermentation, comprising the following steps:

[0020] S1: Inject half a tank of Fe(OH)3 or NaOH solution into the desulfurization tank. Input high-pressure biogas into the pressure pipe through the air inlet pipe. Under the action of air pressure, the second piston rod drives the first piston rod to move downward;

[0021] S2: The semiconductor refrigeration sheet respectively cools and heats the media inside the cooling spiral pipe and the heating spiral pipe. The first piston rod drives the media inside the cooling spiral pipe and the heating spiral pipe to flow, thereby heating and cooling the inside of the desulfurization tank and the water removal tank respectively;

[0022] S3: When the permanent magnet corresponds to the magnetic switch and the solenoid valve is opened, biogas enters the desulfurization tank through the gas transmission pipe and the filter pipe. The biogas moves upward along the spiral air duct from the bottom of the desulfurization tank. During the upward movement of the biogas, it reacts with the solution for desulfurization. When the biogas is discharged from the solution, the spiral spray pipe sprays it; the desulfurized biogas enters from the bottom of the water removal tank through the pipeline, and is condensed and dewatered after contacting the second fin.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] The present invention can effectively remove sulfides in biogas through Fe(OH)3 or NaOH solution in the desulfurization tank. The design of the spiral air duct makes the biogas move spirally upward in the desulfurization tank, prolonging the contact time between the biogas and the solution and improving the desulfurization effect. The spiral spray pipe sprays the biogas again after it exits the solution, further removing impurities in the biogas, enhancing the desulfurization effect, and further purifying the biogas through spraying. The work of the piston rod and the semiconductor refrigeration sheet is driven by the biogas pressure, realizing the effective utilization of energy and automatic control. When the biogas pressure reaches the preset value, the solenoid valve automatically opens, and the biogas enters the desulfurization tank, ensuring the continuity and stability of biogas purification. Through the heating end and the cooling end of the semiconductor refrigeration sheet, the heating of the desulfurization tank and the refrigeration of the water removal tank are respectively realized, simplifying the system structure and improving the energy utilization efficiency. The heating part heats the desulfurization tank through the heating spiral pipe and the heating pipe, which helps to maintain the temperature of the desulfurization solution and improve the desulfurization efficiency. The refrigeration part refrigerates the water removal tank through the cooling spiral pipe and the cooling pipe, which helps to condense the moisture in the biogas and achieve the dehumidification effect. The design of the cooling pipe and the fins in the water removal tank effectively condenses and removes the moisture in the biogas by reducing the biogas temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of the present invention;

[0026] Figure 2 is a schematic structural diagram of the spiral air duct of the present invention;

[0027] Figure 3 is a schematic structural diagram of the pressure pipe of the present invention;

[0028] Figure 4 is a schematic structural diagram of the spiral blade of the present invention;

[0029] Figure 5 is a schematic structural diagram of the cooling spiral pipe of the present invention;

[0030] Figure 6 is a schematic structural diagram of the water removal tank of the present invention;

[0031] Figure 7 is a schematic structural diagram of the second fin of the present invention.

[0032] In the figure: 1, desulfurization tank; 2, filter tube; 3, spiral blade; 4, spiral air duct; 5, air outlet pipe; 6, water pump; 7, spiral spray pipe; 8, heating pipe; 9, fixing bracket; 10, heating box; 11, cooling box; 12, semiconductor refrigeration sheet; 13, cooling spiral pipe; 14, heating spiral pipe; 15, first fin; 16, first negative pressure pipe; 17, first piston rod; 18, spring; 19, lifting rod; 20, second piston rod; 21, magnetic switch; 22, permanent magnet; 23, pressure pipe; 24, air inlet pipe; 25, gas transmission pipe; 26, solenoid valve; 27, second negative pressure pipe; 28, water removal tank; 29, second fin; 30, cooling pipe. Specific embodiments

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] Please refer to Figure 1-7 , an anaerobic fermentation internal biogas purification device provided by an embodiment of the present invention includes: a desulfurization tank 1 filled with Fe(OH)3 or NaOH solution inside; a filter tube 2 provided with a semi-permeable membrane inside, separating carbon dioxide through the semi-permeable membrane made of polyimide material, the filter tube 2 is fixedly connected inside the desulfurization tank 1, and a spiral blade 3 is fixedly connected to the outside of the filter tube 2. The spiral blade 3 divides the space between the filter tube 2 and the desulfurization tank 1 into a spiral air duct 4 for guiding biogas to be spirally transported from bottom to top. A spiral spray pipe 7 and a heating part for heating the solution are provided inside the spiral air duct 4; a water removal tank 28 is placed on one side of the desulfurization tank 1, and a cooling part is provided inside the water removal tank 28 for removing water from the biogas; an air intake driving assembly is placed between the desulfurization tank 1 and the water removal tank 28. The air intake driving assembly includes a pressure pipe 23 for introducing biogas, a pressure driving part is provided inside the pressure pipe 23, a semiconductor refrigeration sheet 12 is arranged below the pressure pipe 23, the heating end of the semiconductor refrigeration sheet 12 heats the heating part and its cooling end cools the cooling part; when biogas enters the pressure pipe 23 to increase the internal pressure, under the action of pressure, the pressure driving part drives the flow of the media in the refrigeration part and the heating part. When the pressure in the pressure pipe 23 reaches the preset value, the biogas enters the desulfurization tank 1 through the filter tube 2, and the pressure driving part automatically resets.

[0035] The bottom of the filter tube 2 is fixedly connected with an air outlet pipe 5 through a one-way valve. The bottom of the desulfurization tank 1 is fixedly connected with a water pump 6. The water inlet end of the water pump 6 is communicated with the bottom of the desulfurization tank 1, and the output end of the water pump 6 is fixedly connected with the spiral spray pipe 7 for spraying the solution inside the desulfurization tank 1 along the flowing direction of the spiral air duct 4.

[0036] The one-way valve controls the biogas to enter the pressure pipe 23 only along the inlet pipe 24. During the biogas purification process, the water pump 6 continuously conveys the solution inside the desulfurization tank 1 from the bottom upwards into the spiral spray pipe 7 and then sprays it out. The height of the spiral spray pipe 7 is higher than the height of the solution, so that the biogas flowing along the spiral air duct 4 is discharged from the solution and then continues to move upwards along the spiral air duct 4. During this period, the spiral spray pipe 7 sprays the biogas to carry out a secondary desulfurization reaction on the biogas.

[0037] The pressure driving part includes an inlet pipe 24. The top of the pressure pipe 23 is fixedly connected to the inlet pipe 24 through a one-way valve. The top of the pressure pipe 23 is fixedly connected with an electromagnetic valve 26. The air outlet end of the electromagnetic valve 26 is fixedly connected with an air delivery pipe 25. One end of the air delivery pipe 25 is connected to the filter pipe 2. A second piston rod 20 is slidably connected inside the pressure pipe 23. The top of the second piston rod 20 is fixedly connected with a permanent magnet 22. One side of the bottom of the pressure pipe 23 is fixedly connected with a magnetic switch 21. The magnetic switch 21 is electrically connected to the electromagnetic valve 26. The bottom of the second piston rod 20 is fixedly connected with a lifting rod 19. The bottom of the lifting rod 19 is fixedly connected with two first piston rods 17. The two first piston rods 17 are respectively slidably connected to the inner walls of the first negative pressure pipe 16 and the second negative pressure pipe 27. The bottom of the first piston rod 17 is fixedly connected with a spring 18.

[0038] Connect the biogas to the inlet pipe 24 through a high-pressure air pump. The biogas enters the pressure pipe 23 through the inlet pipe 24 and the one-way valve. Under the action of pressure, the second piston rod 20 moves downwards. The second piston rod 20 drives the first piston rod 17 to move downwards through the lifting rod 19. The first piston rod 17 moves downwards in the first negative pressure pipe 16 and the second negative pressure pipe 27 and compresses the spring 18. When the permanent magnet 22 corresponds to the magnetic switch 21, under the action of the timer, the electromagnetic valve 26 is electrified for a short period. The electromagnetic valve 26 is opened when electrified. The spring 18 resets and drives the lifting rod 19 to move upwards through the first piston rod 17. The lifting rod 19 drives the second piston rod 20 to move upwards, so that the biogas enters the filter pipe 2 through the electromagnetic valve 26 and the air delivery pipe 25 and is discharged from the air outlet pipe 5 at the bottom of the filter pipe 2 and enters the desulfurization tank 1. The biogas moves upwards along the spiral air duct 4 in the desulfurization tank 1 and reacts with the solution.

[0039] The heating part includes a heating box 10 fixedly connected to the bottom of the first negative pressure pipe 16. The heating end of the semiconductor refrigeration sheet 12 is connected to the inside of the heating box 10 through the first fin 15. Inside the heating box 10 and at the bottom of the first negative pressure pipe 16, a heating spiral pipe 14 is fixedly connected. One end of the heating spiral pipe 14 is fixedly connected to a heating pipe 8. The heating pipe 8 is spirally arranged along the spiral air duct 4 in the desulfurization tank 1. The other end of the heating pipe 8 is connected to the top of the first negative pressure pipe 16.

[0040] The heating end of the semiconductor refrigeration sheet 12 heats the liquid in the heating box 10 through the first fin 15, thereby heating the heating spiral tube 14 through the liquid. When the first piston rod 17 moves downward inside the first negative pressure tube 16, the water inside the first negative pressure tube 16 is squeezed downward, so that the water enters the heating tube 8 after being heated through the heating spiral tube 14, and the desulfurization tank 1 is heated through the heating tube 8. The water enters the upper part of the piston of the first piston rod 17 inside the first negative pressure tube 16 through the heating tube 8. When the solenoid valve 26 is opened, the spring 18 drives the first piston rod 17 to move upward, so that the first piston rod 17 squeezes the water inside the first negative pressure tube 16 again, and enters the heating spiral tube 14 through the heating tube 8 again for heating.

[0041] The refrigeration part includes a cooling box 11 fixedly connected to the refrigeration end of the semiconductor refrigeration sheet 12. The inside of the cooling box 11 is connected to the refrigeration end of the cooling box 11 through the first fin 15. A cooling spiral tube 13 is fixedly connected inside the cooling box 11. One end of the cooling spiral tube 13 is connected to the bottom of the second negative pressure tube 27, and the other end of the cooling spiral tube 13 is fixedly connected to a cooling tube 30. The cooling tube 30 is fixedly connected inside the water removal tank 28. A plurality of second fins 29 are fixedly connected at equal intervals on the outer side of the cooling tube 30. The other end of the cooling tube 30 is connected to the top of the second negative pressure tube 27. A fixing frame 9 is fixedly connected to the tops of the first negative pressure tube 16 and the second negative pressure tube 27. The heating box 10 and the cooling box 11 are both fixedly connected to the bottom of the fixing frame 9. The cooling spiral tube 13 and the heating spiral tube 14 are both fixedly connected to the first fin 15. The first piston rod 17 is slidably connected to the fixing frame 9. A blower for extracting biogas is provided at the top of the water removal tank 28, and a water collecting pipe is provided at the bottom of the water removal tank 28.

[0042] By lifting and lowering the first piston rod 17 inside the second negative pressure tube 27, the coolant is pumped to flow between the cooling spiral tube 13 and the cooling tube 30, so that the low temperature of the semiconductor refrigeration sheet 12 is transferred to the water removal tank 28 through the cooling tube 30 and the second fins 29. The desulfurized biogas enters the bottom of the water removal tank 28 through a pipeline. The biogas moves from bottom to top through the blower at the top of the water removal tank 28. The biogas contacts the second fins 29 and the cooling tube 30, and the moisture in the biogas is condensed out by reducing the gas temperature and flows to the water collecting pipe at the bottom of the water removal tank 28.

[0043] In the present invention, half a tank of Fe(OH)3 or NaOH solution is injected into the desulfurization tank 1. High-pressure biogas is input into the pressure pipe 23 through the air inlet pipe 24. Under the action of air pressure, the second piston rod 20 drives the first piston rod 17 to move downward. The semiconductor refrigeration sheet 12 refrigerates and heats the media inside the cooling spiral pipe 13 and the heating spiral pipe 14 respectively. The first piston rod 17 drives the media inside the cooling spiral pipe 13 and the heating spiral pipe 14 to flow, so as to heat and refrigerate the inside of the desulfurization tank 1 and the water removal tank 28 respectively. When the permanent magnet 22 corresponds to the magnetic switch 21 and the solenoid valve 26 is opened, biogas enters the desulfurization tank 1 through the gas transmission pipe 25 and the filter pipe 2. The biogas moves upward along the spiral air duct 4 from the bottom of the desulfurization tank 1. During the upward movement of the biogas, it reacts with the solution for desulfurization. When the biogas is discharged from the solution, the spiral spray pipe 7 sprays it. The desulfurized biogas enters from the bottom of the water removal tank 28 through the pipeline and is condensed and dewatered after contacting the second fin 29.

[0044] As described above, the above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. An anaerobic fermentation internal biogas purification device, characterized in that: Comprising: A desulfurization tank (1) filled with Fe(OH)3 or NaOH solution inside; A filter tube (2) with a semi-permeable membrane inside. The filter tube (2) is fixedly connected inside the desulfurization tank (1). A spiral blade (3) is fixedly connected to the outside of the filter tube (2). The spiral blade (3) divides the space between the filter tube (2) and the desulfurization tank (1) into a spiral air duct (4) for guiding biogas to be transported spirally from bottom to top. A spiral spray pipe (7) and a heating part for heating the solution are arranged inside the spiral air duct (4); A water removal tank (28) placed on one side of the desulfurization tank. A cooling part is arranged inside the water removal tank (28) for removing water from the biogas; An air inlet driving assembly placed between the desulfurization tank (1) and the water removal tank (28). The air inlet driving assembly includes a pressure pipe (23) for introducing biogas. A pressure driving part is arranged inside the pressure pipe (23). A semiconductor refrigerating sheet (12) is arranged below the pressure pipe (23). The heating end of the semiconductor refrigerating sheet (12) heats the heating part and its refrigerating end cools the cooling part; When biogas enters the pressure pipe (23), the internal pressure increases. Under the action of pressure, the pressure driving part drives the flow of the medium in the refrigerating part and the heating part. When the pressure in the pressure pipe (23) reaches the preset value, the biogas enters the desulfurization tank (1) through the filter tube (2), and the pressure driving part automatically resets.

2. The anaerobic fermentation internal biogas purification device according to claim 1, characterized in that: The bottom of the filter tube (2) is fixedly connected with an air outlet pipe (5) through a one-way valve. The bottom of the desulfurization tank (1) is fixedly connected with a water pump (6). The water inlet end of the water pump (6) is communicated with the bottom of the desulfurization tank (1). The output end of the water pump (6) is fixedly connected with the spiral spray pipe (7) for spraying the solution inside the desulfurization tank (1) along the flowing direction of the spiral air duct (4).

3. The anaerobic fermentation internal biogas purification device according to claim 1, wherein: The pressure driving part includes an air inlet pipe (24). The top of the pressure pipe (23) is fixedly connected with an air inlet pipe (24) through a one-way valve. The top of the pressure pipe (23) is fixedly connected with an electromagnetic valve (26). The air outlet end of the electromagnetic valve (26) is fixedly connected with an air delivery pipe (25). One end of the air delivery pipe (25) is connected with the filter tube (2). A second piston rod (20) is slidably connected inside the pressure pipe (23). A permanent magnet (22) is fixedly connected to the top of the second piston rod (20). A magnetic switch (21) is fixedly connected to one side of the bottom of the pressure pipe (23). The magnetic switch (21) is electrically connected with the electromagnetic valve (26).

4. An anaerobic fermentation internal biogas purification device according to claim 1, characterized in that: The bottom of the second piston rod (20) is fixedly connected with a lifting rod (19). The bottom of the lifting rod (19) is fixedly connected with two first piston rods (17). The two first piston rods (17) are respectively slidably connected with the inner walls of the first negative pressure pipe (16) and the second negative pressure pipe (27). A spring (18) is fixedly connected to the bottom of the first piston rod (17).

5. The anaerobic fermentation internal biogas purification device according to claim 1, characterized in that: The heating part includes a heating box (10) fixedly connected to the bottom of the first negative pressure pipe (16). The heating end of the semiconductor refrigeration sheet (12) is connected to the inside of the heating box (10) through the first fin (15). Inside the heating box (10) and at the bottom of the first negative pressure pipe (16), a heating spiral pipe (14) is fixedly connected. One end of the heating spiral pipe (14) is fixedly connected to a heating pipe (8). The heating pipe (8) is spirally arranged in the desulfurization tank (1) along the spiral air duct (4). The other end of the heating pipe (8) is connected to the top of the first negative pressure pipe (16).

6. The anaerobic fermentation internal biogas purification device according to claim 1, characterized in that: The refrigeration part includes a cooling box (11) fixedly connected to the refrigeration end of the semiconductor refrigeration sheet (12). The inside of the cooling box (11) is connected to the refrigeration end of the cooling box (11) through the first fin (15). Inside the cooling box (11), a cooling spiral pipe (13) is fixedly connected. One end of the cooling spiral pipe (13) is connected to the bottom of the second negative pressure pipe (27). The other end of the cooling spiral pipe (13) is fixedly connected to a cooling pipe (30). The cooling pipe (30) is fixedly connected in the water removal tank (28). A plurality of second fins (29) are fixedly connected at equal intervals on the outer side of the cooling pipe (30). The other end of the cooling pipe (30) is connected to the top of the second negative pressure pipe (27).

7. The anaerobic fermentation internal biogas purification device according to claim 1, characterized in that: A fixing frame (9) is fixedly connected to the tops of the first negative pressure pipe (16) and the second negative pressure pipe (27). The heating box (10) and the cooling box (11) are both fixedly connected to the bottom of the fixing frame (9). The cooling spiral pipe (13) and the heating spiral pipe (14) are both fixedly connected to the first fin (15). The first piston rod (17) is slidably connected to the fixing frame (9).

8. An anaerobic fermentation internal biogas purification device according to claim 1, characterized in that: A blower for extracting biogas is provided at the top of the water removal tank (28), and a water collecting pipe is provided at the bottom of the water removal tank (28).

9. A method for using the anaerobic fermentation internal biogas purification device as described in claim 1, characterized in that: It includes the following steps: S1: Inject half a tank of Fe(OH)3 or NaOH solution into the desulfurization tank (1). Input high-pressure biogas into the pressure pipe (23) through the air inlet pipe (24). Under the action of air pressure, the second piston rod (20) drives the first piston rod (17) to move downward; S2: The semiconductor refrigeration sheet (12) respectively cools and heats the media inside the cooling spiral pipe (13) and the heating spiral pipe (14). The first piston rod (17) drives the media inside the cooling spiral pipe (13) and the heating spiral pipe (14) to flow, so as to heat and cool the inside of the desulfurization tank (1) and the water removal tank (28) respectively; S3: When the permanent magnet (22) corresponds to the magnetic switch (21) and the solenoid valve (26) is opened, biogas enters the desulfurization tank (1) through the gas transmission pipe (25) and the filter pipe (2). The biogas moves upward from the bottom of the desulfurization tank (1) along the spiral air duct (4). During the upward movement of the biogas, it reacts with the solution for desulfurization. When the biogas is discharged from the solution, the spiral spray pipe (7) sprays it; The desulfurized biogas enters from the bottom of the water removal tank (28) through the pipeline and is condensed and dewatered after contacting the second fin (29).

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