Device for concentrating methane from marsh gas

Abstract

The utility model discloses a device for concentrating methane from marsh gas, which comprises a marsh gas compressor, a desulfurizing tower and an adsorption tower, the input end of the marsh gas compressor is communicated with a gas source, the output end of the marsh gas compressor is communicated with the input end of the desulfurizing tower, the output end of the desulfurizing tower is communicated with the input end of the adsorption tower, and a waste gas pipe and a product pipe are arranged on the adsorption tower. Incoming biogas is pressurized through the biogas compressor, then desulfurization is performed in the desulfurization tower, and then water and CO2 are removed in the adsorption tower, so that not only can water and H2S be completely removed, but also the processing efficiency can be improved.

Description

Technical Field

[0001] This utility model relates to the field of methane extraction, and in particular to a biogas methane concentration device. Background Technology

[0002] At a pressure of 0.1 kPa and a temperature less than 40℃, the composition of biogas is as follows:

[0003] composition <![CDATA[CH4]]> <![CDATA[CO2]]> CnHm Volatile substances Air <![CDATA[H2S]]> Vol% 55.32 42.55 0 0 2.03 0.10

[0004] In the process of methane enrichment from biogas, it is necessary to remove a large amount of CO2 and H2S from the gas. After treatment, H2S and a small amount of water in the air need to be completely removed, while a small amount of CO2 can be retained. In the existing technology, H2S removal, CO2 removal and water removal are all done using different equipment, and then these devices are connected in series. However, in the process of operation, there are still cases where water removal and H2S removal are incomplete. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a biogas methane enrichment device.

[0006] The objective of this utility model is achieved through the following technical solution:

[0007] A biogas methane enrichment device includes a biogas compressor, a desulfurization tower, and an adsorption tower. The input end of the biogas compressor is connected to a gas source, the output end of the biogas compressor is connected to the input end of the desulfurization tower, the output end of the desulfurization tower is connected to the input end of the adsorption tower, and the adsorption tower is equipped with an exhaust gas pipe and a product pipe.

[0008] Furthermore, at least two desulfurization towers are arranged in parallel on the output end of the biogas compressor, a first desulfurization control valve is provided on the input end of each desulfurization tower, and a second desulfurization control valve is provided on the output end of each desulfurization tower.

[0009] Furthermore, at least two adsorption towers are arranged in parallel at the output end of the desulfurization tower, an adsorption control valve is provided at the input end of the adsorption tower, an exhaust gas control valve is provided on the exhaust gas pipe, and a product control valve is provided on the product pipe.

[0010] Furthermore, the output end of the product pipe is connected to the input end of the product main pipe, and a product main control valve is provided on the product main pipe.

[0011] Furthermore, a mixing tank is provided on the product main pipe, and the mixing tank is arranged in parallel with the product main control valve. A first mixing control valve is provided between the input end of the mixing tank and the product main pipe, and a second mixing control valve is provided between the output end of the mixing tank and the product main pipe.

[0012] Furthermore, a vacuum tube is arranged in parallel between the input end of the product tube and the main product tube, a vacuum pump is installed on the vacuum tube, a vacuum valve is installed on the vacuum tube, and the vacuum valve is located between the adsorption tower and the vacuum pump.

[0013] Furthermore, the upper part of each exhaust pipe is connected to a balance pipe, and a balance control valve is provided between the exhaust pipe and the balance pipe.

[0014] Furthermore, the upper part of the exhaust pipe is connected to a buffer pipe, a buffer tank is connected to the end of the buffer pipe, and a buffer valve is connected between the exhaust pipe and the buffer pipe.

[0015] The beneficial effects of this utility model are:

[0016] 1) In this technology, the incoming biogas is pressurized by a biogas compressor, then desulfurized in a desulfurization tower, and then water and CO2 are removed in an adsorption tower. This not only completely removes water and H2S, but also improves processing efficiency.

[0017] 2) In this technology, two desulfurization towers are set up at the same time. When one desulfurization tower is working, the other desulfurization tower is being regenerated, so continuous production can be achieved and the production of this device will not be interrupted.

[0018] 3) In this technology, multiple adsorption towers are set up, and the adsorption towers can also adopt a combination of partial use and partial regeneration, which can better adsorb water vapor and CO2. Attached Figure Description

[0019] Figure 1 This is a connection structure diagram of the device;

[0020] In the diagram, 1-biogas compressor, 2-desulfurization tower, 3-adsorption tower, 4-exhaust gas pipe, 5-product pipe, 6-first desulfurization control valve, 7-second desulfurization control valve, 8-adsorption control valve, 9-product control valve, 10-exhaust gas control valve, 11-product main pipe, 12-product main control valve, 13-mixing tank, 14-first mixing control valve, 15-second mixing control valve, 16-vacuum pipe, 17-vacuum pump, 18-vacuum valve, 19-balance pipe, 20-balance control valve, 21-buffer pipe, 22-buffer tank, 23-buffer valve. Detailed Implementation

[0021] The technical solution of this utility model will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0022] See Figure 1 This utility model provides a technical solution:

[0023] A biogas methane enrichment unit includes a biogas compressor 1, a desulfurization tower 2, and an adsorption tower 3. The input end of the biogas compressor 1 is connected to a gas source, and the output end of the biogas compressor 1 is connected to the input end of the desulfurization tower 2. The output end of the desulfurization tower 2 is connected to the input end of the adsorption tower 3. The adsorption tower 3 is equipped with an exhaust pipe 4 and a product pipe 5. The biogas compressor 1 is a conventional compound compressor that compresses biogas to 0.6 MPaG and cools it before sending it to the desulfurization tower 2 for desulfurization. The compressed biogas enters the desulfurization tower 2, which is filled with a conventional biogas-specific solid desulfurizing agent. This desulfurizing agent has high desulfurization activity and sulfur capacity, and its main components with desulfurization activity at room temperature are α-Fe₂O₃·H₂O and γ-Fe₂O₃·H₂O. When biogas passes through, the hydrogen sulfide in the biogas reacts with the desulfurizing agent to form iron sulfide: Fe2O3·H2O + 3H2S → Fe2S3·H2O + 3H2O. When oxygen is present in the biogas, the generated iron sulfide reacts with oxygen to form iron oxide and precipitate sulfur. The reaction is: Fe2S3·H2O + 3 / 2O2 → Fe2O3·H2O + 3S. This desulfurization and regeneration process continues until the pores of the desulfurizing agent are blocked and it becomes ineffective. During this process, the active iron oxide hydrate solid desulfurizing agent acts essentially as a catalyst. To improve the utilization efficiency of the desulfurizing agent, the two desulfurization towers 2 in this device can be operated in parallel or in series. When the H2S content at the outlet of the first desulfurization tower 2 exceeds 10 mg / Nm³... 3When the first desulfurization tower (2) is connected in series with the second tower, the H2S concentration at the outlet of the first tower approaches the concentration of the raw gas. At this point, the desulfurizer in the first tower is considered ineffective, and the first tower is removed from operation. Only the second tower is used. The desulfurizer in the first tower is replaced, and then the system is switched to a series operation with the second tower preceding the first. Similarly, the desulfurizer in the second tower can be replaced online. Under normal conditions, the desulfurizer is replaced annually. The purified biogas after desulfurization enters the VPSA unit. CO2 and other impurities are adsorbed in the adsorption tower 3. The top product of the adsorption tower 3 is methane gas, whose technical indicators meet the Class II requirements of GB17820-2012 Natural Gas. CO2 and other impurities are discharged from the system via reverse release and vacuuming. Simultaneously, the adsorbent is desorbed. Due to the high CO2 content and low calorific value, the CO2 is either flared on-site or directly vented. The VPSA unit uses five adsorption towers 3 connected in parallel. Each adsorption tower 3 sequentially undergoes adsorption, depressurization, reverse release, evacuation, pressurization, and final pressurization to complete one cycle. From a microscopic perspective, the desulfurization process can be broken down into the following steps: H2S molecules diffuse inward through the gas film at the gas-solid interface and the micropores of the desulfurizing agent to the surface of iron oxide hydrate; H2S dissolves in the water film on the surface of iron oxide and dissociates into HS. - S2 - Ions; HS - S2 - Ions and lattice oxygen (OH) in hydrated iron oxide - O2 - The iron oxides undergo mutual substitution to generate Fe2S3.H2O; the lattice rearranges, and the needle-like and cubic structures of hydrated iron oxide are transformed into monoclinic crystals of hydrated iron sulfide; the generated surface iron sulfide reacts with the inner iron oxide at the interface, and sulfur diffuses inward; after the surface is renewed, the surface iron oxide continues to absorb hydrogen sulfide.

[0024] After processing by this device, the final results are shown in the table below:

[0025]

[0026]

[0027] In some embodiments, at least two desulfurization towers 2 are arranged in parallel at the output end of the biogas compressor 1. Each desulfurization tower 2 is equipped with a first desulfurization control valve 6 at its input end and a second desulfurization control valve 7 at its output end. Generally, the two desulfurization towers 2 operate independently; one tower performs desulfurization while the other performs regeneration. Each desulfurization tower 2 is independently connected to a first desulfurization control valve 6 and a second desulfurization control valve 7. When a desulfurization tower 2 is operating, both its corresponding first and second desulfurization control valves 6 and 7 are open; when the tower 2 is regenerating, both are closed. Both the first and second desulfurization control valves 6 and 7 are control valves in the prior art.

[0028] In some embodiments, at least two adsorption towers 3 are arranged in parallel at the output end of the desulfurization tower 2. An adsorption control valve 8 is installed at the input end of each adsorption tower 3, an exhaust gas control valve 10 is installed on the exhaust gas pipe 4, and a product control valve 9 is installed on the product pipe 5. In this technology, five adsorption towers 3 are provided. These five adsorption towers 3 can operate simultaneously, or a select few can operate, or some can operate while others are regenerated. The adsorption control valve 8, exhaust gas control valve 10, and product control valve 9 are all control valves in the prior art.

[0029] In some embodiments, the output end of product pipe 5 is connected to the input end of product main pipe 11, and a product main control valve 12 is provided on product main pipe 11. A mixing tank 13 is provided on product main pipe 11, and the mixing tank 13 is arranged in parallel with the product main control valve 12. A first mixing control valve 14 is provided between the input end of mixing tank 13 and product main pipe 11, and a second mixing control valve 15 is provided between the output end of mixing tank 13 and product main pipe 11. A vacuum pipe 16 is arranged in parallel between the input end of product pipe 5 and product main pipe 11. A vacuum pump 17 is provided on vacuum pipe 16, and a vacuum valve 18 is provided on vacuum pipe 16. The vacuum valve 18 is located between adsorption tower 3 and vacuum pump 17. Each adsorption tower 3 is connected to a product pipe 5, and all five product pipes 5 are connected to product main pipe 11. If the gas discharged from adsorption tower 3 is stable, the main product control valve 12 is open, and the first mixing control valve 14 and the second mixing control valve 15 are closed. If the gas discharged from adsorption tower 3 is unstable, the main product control valve 12 is closed, and the first mixing control valve 14 and the second mixing control valve 15 are open. The gas enters the mixing tank 13 for buffering, and after buffering, the gas discharged from the main product pipe 11 is stable. The main product control valve 12, the first mixing control valve 14, and the second mixing control valve 15 are all control valves in the prior art.

[0030] In some embodiments, the upper part of each exhaust pipe 4 is connected to a balance pipe 19, and a balance control valve 20 is provided between the exhaust pipe 4 and the balance pipe 19. The upper part of each exhaust pipe 4 is connected to a buffer pipe 21, and a buffer tank 22 is connected to the end of the buffer pipe 21. A buffer valve 23 is connected between the exhaust pipe 4 and the buffer pipe 21. After the vacuum pump 17 evacuates one or more adsorption towers 3, the gas pressure inside the five adsorption towers 3 varies. By using the balance pipe 19 and opening the corresponding balance control valve 20, the internal gas pressure of the adsorption towers 3 used simultaneously can be made the same. The buffer tank 22 stores spare gas and can also enter the adsorption tower 3 through the buffer pipe 21 to balance the gas pressure. The buffer tank 22 is a pressure tank in the prior art, and the balance control valve 20 and the buffer valve 23 are both valves in the prior art. The balance pipe 19 is connected to the five exhaust pipes 4, and the five exhaust pipes 4 are also connected to the buffer pipe 21.

[0031] In this utility model, unless otherwise explicitly specified and limited, the terms "set", "install", "connect" and other such terms should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0032] The above description is merely a preferred embodiment of this utility model. It should be understood that this utility model is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this utility model should be protected within the scope of the appended claims.

Claims

1. A biogas methane-enrichment plant, characterized in that: The methane gas compressor (1), the desulfurization tower (2) and the adsorption tower (3), the input end of the methane gas compressor (1) is communicated with the gas source, the output end of the methane gas compressor (1) is communicated with the input end of the desulfurization tower (2), the output end of the desulfurization tower (2) is communicated with the input end of the adsorption tower (3), the adsorption tower (3) is provided with waste gas pipe (4) and product pipe (5).

2. The biogas methane-enriching device according to claim 1, characterized in that: The output end of the methane gas compressor (1) is provided with at least two desulfurization towers (2), the input end of each desulfurization tower (2) is provided with a first desulfurization control valve (6), and the output end of the desulfurization tower (2) is provided with a second desulfurization control valve (7).

3. A biogas methane enrichment device according to claim 1 or 2, characterised in that: The output end of the desulfurization tower (2) is provided with at least two adsorption towers (3), the input end of the adsorption tower (3) is provided with an adsorption control valve (8), the waste gas pipe (4) is provided with a waste gas control valve (10), and the product pipe (5) is provided with a product control valve (9).

4. The biogas methane-enriching device according to claim 3, characterized in that: The output end of the product pipe (5) is communicated with the input end of the product main pipe (11), and the product main pipe (11) is provided with a product main control valve (12).

5. The biogas methane-enriching device according to claim 4, characterized in that: The product main pipe (11) is provided with a mixing tank (13), the mixing tank (13) is arranged in parallel with the product main control valve (12), a first mixing control valve (14) is arranged between the input end of the mixing tank (13) and the product main pipe (11), and a second mixing control valve (15) is arranged between the output end of the mixing tank (13) and the product main pipe (11).

6. The biogas methane enrichment device according to claim 4, characterized in that: The input end of the product pipe (5) is arranged in parallel with the vacuum pipe (16) between the product main pipe (11), the vacuum pipe (16) is provided with a vacuum pump (17), the vacuum pipe (16) is provided with a vacuum valve (18), and the vacuum valve (18) is arranged between the adsorption tower (3) and the vacuum pump (17).

7. The biogas methane-enriching device according to claim 3, characterized in that: The waste gas pipe (4) is communicated with the balance pipe (19), and a balance control valve (20) is arranged between the waste gas pipe (4) and the balance pipe (19).

8. The biogas methane enrichment device according to claim 3, characterized in that: The waste gas pipe (4) is communicated with the buffer pipe (21), the end of the buffer pipe (21) is connected with a buffer tank (22), and a buffer valve (23) is connected between the waste gas pipe (4) and the buffer pipe (21).

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