Method for converting municipal waste landfill gases

Abstract

A kind of life garbage landfill gas conversion method, comprising: one, gas is sprayed to remove particulate matter and soluble gas, then target gas is separated;Two, target gas is introduced into the reaction cavity of intermittent reaction unit, and water is injected to water distribution film in reaction cavity;Water distribution film is provided with upper and lower layers, and water distribution film is uniformly distributed with several nanoscale water-permeable holes, and the orifice is located in the lower surface of film;Water distribution film is loaded with metal particles for catalysis, and metal particles are at least distributed in the lower surface of film and each nanoscale water-permeable hole;Three, reaction cavity is lighted, so that nanometer droplet of water distribution film is light catalysis reacted with target gas in reaction cavity, and the conversion of target gas is realized.The present application realizes the conversion of methane and other organic gases by nanometerizing water in air, so that ·OH is spontaneously generated, is used to activate attack C-H bond in methane.

Description

Technical Field

[0001] This invention relates to the field of hazardous gas treatment, and more specifically to a method for converting gases in municipal solid waste landfills. Background Technology

[0002] While carbon dioxide is the most common greenhouse gas, the greenhouse effect caused by other carbon-containing greenhouse gases, such as methane, is often ten to dozens of times greater than that of carbon dioxide. Therefore, controlling other carbon-containing greenhouse gases, such as methane, is of significant practical importance.

[0003] At the end of the last century, sanitary landfill was the primary method of disposing of municipal solid waste. This not only consumed a large amount of valuable land resources, but also resulted in a stabilization period of over 50 years for the landfilled waste. During this time, the municipal solid waste, sealed within the landfill soil, underwent microbial fermentation, continuously producing landfill gases, primarily methane. If the flow rate of these gases was small, they were directly released into the atmosphere; if the flow rate was large, they were ignited to recover energy, ultimately releasing carbon into the atmosphere as carbon dioxide. Regardless of the emission method, the carbon entered the atmosphere without being fixed. This clearly contradicts the spirit of achieving the "dual carbon" goal. Therefore, it is necessary to fix the carbon in the gases from municipal solid waste landfills.

[0004] Methane is a gas that is difficult to store and transport at room temperature and pressure. If it could be converted into other valuable chemicals, not only would the storage and transportation problems be solved, but its economic value would also be increased. Among these, converting methane into methanol or formic acid not only fixes carbon but also transforms it into more valuable chemicals, which has significant practical and social implications.

[0005] The key to converting methane into methanol or formic acid lies in activating the CH bonds in methane. The hydroxyl radical ·OH has strong oxidizing properties and can be used to activate and attack the CH bonds in methane, converting it into methanol, and even further into formic acid, without producing other byproducts.

[0006] •OH is mainly produced by breaking the peroxide bond in the precursor, hydrogen peroxide. In the liquid phase, hydrogen peroxide is primarily produced through external addition. However, hydrogen peroxide itself is a potentially explosive substance, posing certain safety risks during storage and transportation. Furthermore, hydrogen peroxide may partially decompose into oxygen and water during storage, posing a risk of deterioration. Therefore, developing an in-situ hydrogen peroxide generation method that immediately generates •OH to activate and attack the CH bonds in methane, converting it into methanol, and even further into formic acid, can eliminate the risks associated with hydrogen peroxide storage and transportation. Currently, the in-situ hydrogen peroxide generation and utilization technology based on the two-electron reduction of oxygen, represented by electro-Fenton, is the mainstream approach. However, the complexity of this technology and the ongoing exploration of electrode material durability limit its further practical application. While adding organic substances such as hydroxylamine, triacetic acid, ethylenediaminetetraacetic acid, or ethylenediaminedisuccinic acid can also accelerate the in-situ generation of hydrogen peroxide through the two-electron reduction of oxygen, the dosage cannot be precisely controlled, easily leading to excessive addition and causing new organic pollution in the effluent.

[0007] Therefore, how to overcome the shortcomings of the existing technology is the subject of this invention. Summary of the Invention

[0008] The purpose of this invention is to provide a method for converting gases in municipal solid waste landfills.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A method for converting gases in a municipal solid waste landfill includes:

[0011] Step 1: Spray the gas from the municipal solid waste landfill to remove particulate matter and soluble gases, and then perform gas separation on the sprayed gas to separate the target gas.

[0012] Step 2: Introduce the target gas into the reaction chamber of an intermittent reaction unit, and the gas pressure in the reaction chamber is less than or equal to 30 MPa;

[0013] Simultaneously, water is injected into the water distribution membrane evenly distributed in the reaction chamber; the water distribution membrane has multiple layers and is arranged at intervals in the vertical direction; several nanoscale water-permeable pores are evenly distributed on the water distribution membrane, and the openings of the nanoscale water-permeable pores are located on the lower surface of the water distribution membrane; the water distribution membrane is loaded with metal particles for catalysis, and the metal particles are at least distributed on the lower surface of the water distribution membrane and at each nanoscale water-permeable pore.

[0014] Step 3: Irradiate the reaction chamber with light so that the nanodroplets that seep out of the water-distribution film can undergo a photocatalytic reaction with the target gas in the reaction chamber, thereby realizing the conversion of the target gas.

[0015] In the above scheme, the soluble gas is carbon dioxide, ammonia, sulfur dioxide, hydrogen sulfide, mercaptan, etc.

[0016] In the above scheme, the pore size of the nanoscale water-permeable pores is 0.1~100 nanometers.

[0017] In the above scheme, the water distribution membrane can be a flat sheet membrane, a hollow fiber membrane, a composite membrane, etc.

[0018] Further technical solutions also include step four, where the converted gas is returned to step one through a pipeline for recycling, while the liquid produced after conversion is recovered.

[0019] A further technical solution involves, in step one, demisting and drying the sprayed gas before gas separation. This can be achieved by using a corrugated plate for demisting and drying with activated carbon, concentrated sulfuric acid, or quicklime.

[0020] In a further technical solution, in step two, the target gas entering the reaction chamber is mixed with air through gas distribution. When the target gas is methane, the volume ratio of methane to oxygen is 1:1 to 100.

[0021] In a further technical solution, the metal particles in the water distribution membrane are transition metal particles, such as Fe2O3 / ZnO, Pd / In2O3, Fe2O3@UiO-66, etc., to perform confined catalysis.

[0022] A further technical solution is that, in step three, the wavelength range of the light source used for illumination is from ultraviolet light to visible light.

[0023] A further technical solution involves, in step three, the light rays forming an angle with the lower surface of the water distribution film, the angle ranging from 5° to 45°, with the water distribution film preferably tilted. On one hand, when the light source is horizontally irradiated, the angled design facilitates the light reaching the lower surface of the water distribution film, improving the efficiency of the photocatalytic reaction. On the other hand, the tilted design allows droplets on the water distribution film to collect and be discharged, enabling the products in the water to leave the surface of the film in a timely manner, pulling the reaction towards the target reaction direction, and improving the efficiency of the photocatalytic reaction.

[0024] In a further technical solution, the present invention also relates to a conversion system, which includes a gas separation unit and a batch reaction unit;

[0025] The gas separation unit includes an air inlet zone, a spray packing zone, and a gas separation zone arranged from bottom to top; the spray packing zone includes a spray assembly disposed at the top, and the space below the spray assembly is filled with packing; the gas separation zone is connected to a gas inlet of the intermittent reaction unit through an air outlet pipe.

[0026] The intermittent reaction unit has a reaction chamber, which includes a gas inlet and a gas outlet; the gas inlet is located at the bottom of the reaction chamber, and the gas outlet is located at the top of the reaction chamber; a nanoscale liquid atomization module is provided inside the reaction chamber; the reaction chamber is under positive pressure, and the gas pressure is less than or equal to 30 MPa.

[0027] The nanoscale liquid atomization module includes multiple water distribution membranes, which are spaced apart in the vertical direction. Several nanoscale water-permeable pores are evenly distributed on the water distribution membranes, and the openings of the nanoscale water-permeable pores are located on the lower surface of the water distribution membranes. The water distribution membranes are loaded with metal particles for catalysis, and the metal particles are distributed at least on the lower surface of the water distribution membranes and at each nanoscale water-permeable pore.

[0028] It also includes a water supply module, the water output of which corresponds to the water distribution film in the nanoscale liquid atomization module;

[0029] The side plate of the intermittent reaction unit is a light-transmitting side plate, and a light source for illuminating the reaction chamber is provided on the outer side of the light-transmitting side plate.

[0030] The above technical solution also includes a demisting zone and a drying zone; the air inlet zone, the spray filling zone, the demisting zone, the drying zone and the gas separation zone are arranged from bottom to top.

[0031] The defogging zone can be equipped with corrugated plates for defogging, and the drying zone can be dried using activated carbon, concentrated sulfuric acid, or quicklime.

[0032] In the above technical solution, an air distribution plate is provided between the air inlet area and the spray packing area of ​​the gas separation unit.

[0033] In the above technical solution, a gas distribution plate is provided between the demisting zone, the drying zone and the gas separation zone.

[0034] In the above technical solution, a spray water tank is also provided below the air intake zone. This spray water tank receives the effluent from the spray packing zone and is connected to the spray pipe of the spray packing zone through a return pipe. Chemicals can be added to the spray water to make it alkaline.

[0035] In the above technical solution, the gas outlet of the methane separator in the gas separation zone is connected to the gas inlet of the intermittent reaction unit through the gas outlet pipeline. In addition, the gas separation zone can also be equipped with other separation devices to separate gases such as carbon monoxide and hydrogen, facilitating subsequent recycling.

[0036] In the above technical solution, a pressurizing fan can be connected in series on the gas outlet pipe to keep the gas entering the intermittent reaction unit under positive pressure.

[0037] The above technical solution also includes a gas distribution device. The gas outlet pipe of the gas separation zone and an air inlet pipe are both connected to the gas distribution device, and the gas outlet of the gas distribution device is connected to the gas inlet of the reaction chamber. When the separated target gas is methane, mixing can be used to make the volume ratio of methane to oxygen in the gas entering the reaction chamber 1:1~100.

[0038] In the above technical solution, the side plate of the intermittent reaction unit is made of high-pressure resistant, light-transmitting glass. The wavelength range of the light source used for illumination is from ultraviolet to visible light.

[0039] In the above technical solution, when the gas entering the reaction chamber is methane, the metal particles in the intermittent reaction unit are transition metal particles, such as Fe2O3 / ZnO, Pd / In2O3, Fe2O3@UiO-66, etc., to perform confined catalysis.

[0040] In the above technical solution, the water supply module in the intermittent reaction unit includes multiple water injection frames, each corresponding to one of the water distribution membranes, and the water injection frames are positioned at least on two opposite sides of the water distribution membrane. The water injection frames are hollow tubes with several water outlets, each of which is arranged along the lateral length of the water distribution membrane to supply water to the membrane laterally.

[0041] In the above technical solution, the nanoscale liquid atomization module further includes a rotating support, on which each water distribution film is fixed; the rotating shaft of the rotating support is vertically arranged and located on the center line of the intermittent reaction unit in the vertical direction. This design allows for sufficient irradiation of the reaction chamber and the lower surface of the water distribution film by driving the rotating support to rotate without moving the light source or changing the irradiation angle, thus facilitating efficient photocatalytic reactions.

[0042] In the above technical solution, the gas outlet is also connected to a gas return pipe, which is connected to the gas inlet area of ​​the gas separation unit. A return fan and a gas storage tank can be installed on the gas return pipe.

[0043] In the above technical solution, the effluent from the intermittent reaction unit can be directly discharged, thereby recovering and reusing the methanol and formic acid in the effluent after the conversion is completed.

[0044] This invention discloses a method for converting gases in a municipal solid waste landfill. First, particulate matter and soluble gases are removed by spraying. Then, the sprayed gas undergoes gas separation to separate the target gas. Next, the target gas is introduced into the reaction chamber of an intermittent reaction unit, where the pressure is less than or equal to 30 MPa. Simultaneously, water is injected into a water distribution membrane evenly distributed within the reaction chamber. This water distribution membrane has several nanoscale permeable pores and is loaded with catalytic metal particles, which are distributed at least on the lower surface of the membrane and at each nanoscale permeable pore. Simultaneously, the reaction chamber is irradiated, causing the nanodroplets seeping from the water distribution membrane to undergo a photocatalytic reaction with the target gas in the reaction chamber, thereby achieving the conversion of the target gas.

[0045] The design mechanism of this invention is as follows:

[0046] Water and hydrogen peroxide differ in molecular structure by only one oxygen atom. Studies have shown that hydrogen peroxide can also be produced by atomizing water into nanoscale form and exposing it to air, through the electric field spontaneously generated by the nano-water in the air. The focus of this invention is to nanoscale water in air to spontaneously generate ·OH, which is used to activate and attack the CH bonds in methane.

[0047] Compared with the prior art, the advantages of the present invention are:

[0048] First, it can convert landfill gases such as methane. By converting methane into methanol or formic acid, it can not only fix carbon but also convert it into chemicals with higher economic value, which has important practical and social significance.

[0049] Second, no additional hydrogen peroxide needs to be added, which reduces operating costs and also eliminates the costs and risks associated with hydrogen peroxide storage and transportation.

[0050] Third, it eliminates the problem of excessive addition of hydrogen peroxide, which can lead to organic pollution, when organic matter is added. Attached Figure Description

[0051] Appendix Figure 1 This is a flowchart illustrating the method according to an embodiment of the present invention;

[0052] Appendix Figure 2 This is a schematic diagram of the system structure according to an embodiment of the present invention;

[0053] Appendix Figure 3 This is a schematic diagram of the intermittent reaction unit according to an embodiment of the present invention;

[0054] Appendix Figure 4 This is a schematic diagram of the workflow of an embodiment of the present invention;

[0055] Appendix Figure 5 This is a schematic diagram of the structure of the water distribution membrane combined with the water injection frame in an embodiment of the present invention;

[0056] Appendix Figure 6 This is a cross-sectional structural diagram of the water distribution membrane according to an embodiment of the present invention.

[0057] In the attached diagrams: 1. Gas separation unit; 10. Spray water tank; 101. Return pipeline; 102. Return pump; 11. Air inlet zone; 12. Spray packing zone; 13. Gas separation zone; 14. Spray assembly; 15. Packing material; 16. Air outlet pipeline; 161. First pressurizing fan; 17. Demisting zone; 18. Drying zone; 19. Gas distribution plate; 2. Intermittent reaction unit; 21. Reaction chamber; 22. Water distribution film; 221. Nanoscale water-permeable pores; 222. Metal particles; 23. Gas inlet; 24. Gas outlet; 241. Gas return pipeline; 242. Return fan; 243. Gas storage tank; 25. Nanoscale liquid atomization module; 251. Rotating support; 252. Rotating shaft; 26. Transparent side plate; 27. 271. Air intake duct; 28. Second pressurizing fan; 29. ​​Air distribution device; 20. Water injection frame; 201. Water outlet; 3. Light source. Implementation

[0058] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0059] Example: The present invention will be clearly described below with illustrations and detailed description. Any person skilled in the art who understands the examples of the present invention can make changes and modifications based on the technology taught in the present invention without departing from the spirit and scope of the present invention.

[0060] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this work. Singular forms such as “a,” “this,” “this,” “the,” and “the” as used herein also include plural forms.

[0061] The terms "connection" or "positioning" as used in this article can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, or to two or more components or devices operating or moving with each other.

[0062] The terms “include,” “including,” and “have” used in this article are all open-ended, meaning they include but are not limited to.

[0063] Unless otherwise specified, the terms used herein generally have their ordinary meaning in the context of the art, the subject matter, and the specific context. Certain terms used to describe this case will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the case.

[0064] See appendix Figure 1 As shown, a method for converting gases in a municipal solid waste landfill includes:

[0065] Step 1: Spray the gas from the municipal solid waste landfill to remove particulate matter and soluble gases, and then perform gas separation on the sprayed gas to separate the target gas.

[0066] Step 2: The target gas is introduced into the reaction chamber 21 of an intermittent reaction unit 2, and the gas pressure in the reaction chamber 21 is less than or equal to 30 MPa.

[0067] Simultaneously, water is injected into the water distribution membrane 22 evenly distributed in the reaction chamber 21; the water distribution membrane 22 has multiple layers and is arranged at intervals in the vertical direction; several nanoscale water-permeable pores 221 are evenly distributed on the water distribution membrane 22, and the openings of the nanoscale water-permeable pores 221 are located on the lower surface of the water distribution membrane 22; the water distribution membrane 22 is loaded with metal particles 222 for catalysis, and the metal particles 222 are at least distributed on the lower surface of the water distribution membrane 22 and at each nanoscale water-permeable pore 221, so as to achieve confined catalysis.

[0068] Step 3: Irradiate the reaction chamber 21 with light so that the nanodroplets that seep out of the nanoscale water-permeable pores 221 can carry out a photocatalytic reaction with the target gas in the reaction chamber 21 to achieve the conversion of the target gas.

[0069] The soluble gases include carbon dioxide, ammonia, sulfur dioxide, hydrogen sulfide, and mercaptans.

[0070] The pore size of the nanoscale permeable pores 221 is 0.1~100 nanometers. The water distribution membrane 22 can be a flat sheet membrane, a hollow fiber membrane, a composite membrane, etc.

[0071] Preferably, the process also includes step four, where the converted gas is returned to step one through a pipeline for recycling, while the liquid produced after conversion is recovered.

[0072] Preferably, in step one, the sprayed gas is first demisted and dried before gas separation. A corrugated demisting plate can be used, and activated carbon, concentrated sulfuric acid, or quicklime can be used for drying.

[0073] Preferably, in step two, the target gas entering the reaction chamber 21 is further mixed with air through gas distribution. When the target gas is methane, the volume ratio of methane to oxygen is 1:1 to 100. The metal particles 222 in the water distribution membrane 22 are transition metal particles, such as Fe2O3 / ZnO, Pd / In2O3, Fe2O3@UiO-66, etc., which facilitate confined catalysis.

[0074] Preferably, in step three, the wavelength range of the light source used for illumination is from ultraviolet to visible light.

[0075] Preferably, in step three, the light rays form an angle with the lower surface of the water distribution film 22, the angle ranging from 5° to 45°, and the water distribution film 22 is preferably tilted. On the one hand, when the light source shines horizontally, the angled design facilitates the light reaching the lower surface of the water distribution film 22, improving the efficiency of the photocatalytic reaction; on the other hand, the tilted design allows the droplets on the water distribution film 22 to collect and discharge, enabling the products in the water to leave the surface of the water distribution film 22 in a timely manner, pulling the reaction towards the target reaction direction, and improving the efficiency of the photocatalytic reaction.

[0076] The method of the present invention can be implemented by a gas conversion system, such as... Figure 2 As shown, the conversion system includes a gas separation unit 1 and a batch reaction unit 2.

[0077] The gas separation unit 1 includes an air inlet zone 11, a spray packing zone 12, and a gas separation zone 13 arranged from bottom to top; the spray packing zone 12 includes a spray assembly 14 disposed at the top, and the space below the spray assembly 14 is filled with packing material 15; the gas separation zone 13 is connected to a gas inlet 23 of the intermittent reaction unit 2 through an air outlet pipe 16.

[0078] Preferably, it further includes a demisting zone 17 and a drying zone 18; the air inlet zone 11, the spray packing zone 12, the demisting zone 17, the drying zone 18, and the gas separation zone 13 are arranged from bottom to top. The demisting zone 17 may be equipped with a corrugated plate for demisting, and the drying zone 18 may use activated carbon, concentrated sulfuric acid, or quicklime for drying. The packing 15 in the spray packing zone 12 is a Pall ring or Raschig ring, and the material may be ceramic or plastic.

[0079] Preferably, an air distribution plate 19 is provided between the air inlet zone 11 and the spray packing zone 12 of the gas separation unit 1. An air distribution plate 19 is also provided between the demisting zone 17, the drying zone 18 and the gas separation zone 13.

[0080] Preferably, a spray water tank 10 is also provided below the air intake zone 11. The spray water tank 10 receives the effluent from the spray packing zone 12 and is connected to the spray pipeline of the spray packing zone 12 through a return pipeline 101. The spray water tank 10 can be chemically treated to make the spray solution alkaline. The spray solution can be recycled; a portion is discharged into the water treatment system for treatment, and fresh spray solution is added as needed to maintain the normal operation of the system.

[0081] Preferably, the gas outlet of the methane separator in the gas separation zone 13 is connected to the gas inlet 23 of the intermittent reaction unit 2 via the gas outlet pipe 16. In addition, the gas separation zone 13 can also be equipped with other separation devices to separate gases such as carbon monoxide and hydrogen, facilitating subsequent recycling.

[0082] Preferably, a first pressurizing fan 161 can be connected in series to the gas outlet pipe 16 to keep the gas entering the intermittent reaction unit 2 under positive pressure.

[0083] The intermittent reaction unit 2 has a reaction chamber 21, which includes a gas inlet 23 and a gas outlet 24. The gas inlet 23 is located below the reaction chamber 21, and the gas outlet 24 is located above the reaction chamber 21. A nanoscale liquid atomization module 25 is provided inside the reaction chamber 21. The reaction chamber 21 is under positive pressure, and the gas pressure is less than or equal to 30 MPa.

[0084] The nanoscale liquid atomization module 25 includes multiple water distribution membranes 22, with each water distribution membrane 22 arranged at intervals in the vertical direction; the water distribution membrane can be a flat sheet membrane, a hollow fiber membrane, a composite membrane, etc.

[0085] The water distribution membrane 22 has several nanoscale water-permeable pores 221 evenly distributed on it, with a pore size of 0.1~100 nanometers. The pore openings of the nanoscale water-permeable pores 221 are located on the lower surface of the water distribution membrane 22; the water distribution membrane 22 is loaded with catalytic metal particles 222, and the metal particles 222 are at least distributed on the lower surface of the water distribution membrane 22 and at each nanoscale water-permeable pore 221 (see...). Figure 6 ).

[0086] It also includes a water supply module, the water output of which corresponds to the water distribution film 22 in the nanoscale liquid atomization module 25.

[0087] The intermittent reaction unit 2 has a light-transmitting side plate 26, and a light source for illuminating the reaction chamber 21 is disposed on the outer side of the light-transmitting side plate 26. Preferably, the light-transmitting side plate 26 is high-pressure resistant light-transmitting glass. The wavelength range of the light source used for illumination is from ultraviolet to visible light.

[0088] Preferably, the system also includes a gas distribution device 28, to which the gas outlet pipe 16 of the gas separation zone 13 and an air inlet pipe 27 are connected. The gas outlet of the gas distribution device 28 is connected to the gas inlet 23 of the reaction chamber 21. When the separated target gas is methane, mixing can be used to make the volume ratio of methane to oxygen in the gas entering the reaction chamber 21 1:1~100. A second pressurizing fan 271 can be connected to the air inlet pipe 27.

[0089] Preferably, when the gas entering the reaction chamber 21 is methane, the metal particles 222 in the intermittent reaction unit 2 are transition metal particles, such as Fe2O3 / ZnO, Pd / In2O3, Fe2O3@UiO-66, etc., to perform confined catalysis.

[0090] Preferably, the water supply module in the intermittent reaction unit 2 includes multiple water injection frames 29, each water injection frame 29 corresponding one-to-one with the water distribution membrane 22, and the water injection frame 29 is positioned at least on two opposite sides of the water distribution membrane 22. Figure 5 As shown, the water injection frame 29 is a hollow tube with several water outlets 291. Each of the water outlets 291 is arranged along the side length of the water distribution membrane 22 to supply water to the water distribution membrane 22 laterally.

[0091] Preferred, such as Figure 3 As shown, the water distribution film 22 is inclined with an angle ranging from 5° to 45°. On one hand, when the light source 3 illuminates horizontally, the inclined design facilitates the light reaching the lower surface of the water distribution film 22, improving the efficiency of the photocatalytic reaction. On the other hand, the inclined design allows droplets on the water distribution film to collect and drain, enabling products in the water to leave the surface of the film in a timely manner, pulling the reaction towards the target reaction direction and improving the efficiency of the photocatalytic reaction. In addition, the bottom of the water distribution film 22 can also be illuminated by tilting the light source 3.

[0092] Preferably, the nanoscale liquid atomization module 25 further includes a rotating support 251, on which each of the water distribution films 22 is fixed; the rotation shaft 252 of the rotating support 251 is vertically arranged and located on the center line of the intermittent reaction unit 2 in the vertical direction. This design allows for sufficient irradiation of the reaction chamber 21 and the lower surface of the water distribution film 22 by driving the rotating support 251 to rotate without moving the light source 3 or changing the irradiation angle of the light source 3, thus facilitating a highly efficient photocatalytic reaction.

[0093] Preferably, the gas outlet 24 is also connected to a gas return pipe 241, which is connected to the air inlet area 11 of the gas separation unit 1. A return fan 242 and a gas storage tank 243 may be installed on the gas return pipe 241.

[0094] Preferably, the effluent from the intermittent reaction unit 2 can be directly discharged, thereby recovering and reusing the methanol and formic acid in the effluent after the conversion is completed.

[0095] In addition to using methane as the target gas for conversion, the present invention can also be adapted to convert volatile organic gases such as toluene through some existing, commonly used modifications in the field.

[0096] The working principle of this invention is explained below:

[0097] Gas conversion process in municipal solid waste landfills:

[0098] like Figure 4As shown, the gases in a municipal solid waste landfill mainly contain particulate matter, methane, carbon monoxide, carbon dioxide, sulfur dioxide, hydrogen, ammonia, hydrogen sulfide, and mercaptans. The gas to be treated enters the inlet zone 11 of the gas separation unit 1, is rectified by the gas distribution plate 19, and then enters the spray packing zone 12. After being sprayed counter-currently with an alkaline solution (such as CaOH), soluble gases such as particulate matter, carbon dioxide, ammonia, sulfur dioxide, hydrogen sulfide, and mercaptans can be removed. The effluent passes through the demisting zone 17 to remove water vapor, and is dried by activated carbon, concentrated sulfuric acid, or quicklime. After being rectified by the gas distribution plate 19, it enters the gas separation zone 13. In the gas separation zone 13, methane, carbon monoxide, and hydrogen can be separated and enriched through the separation action of a two-stage membrane, zeolite molecular sieve, MOFs material, or COFs material. The spray liquid falls into the spray water tank 10 and is reused in the spray dust removal process via the return pump 102. The spray solution is kept alkaline by adding some alkaline agents.

[0099] In this process, methane is pressurized and fed into the reaction chamber 21 of the pressure-resistant intermittent reaction unit 2. Simultaneously, air is pressurized and water is pumped into the water distribution membrane 22 via a pressurized pump. Light is irradiated into the reaction chamber 21 through the light-transmitting side plate 26. The reaction is intermittent. By controlling the input pressure, the particle size of the water exiting the nanoscale permeable pores 221 on the water distribution membrane 22 is adjusted, maintaining the water particles at the nanoscale while exposed to the gas, thus spontaneously generating hydrogen peroxide. Metal particles 222 are loaded in the nanoscale permeable pores 221 of the water distribution membrane 22, and the hydrogen peroxide produced by in-situ catalysis decomposes to generate ·OH. The water distribution membrane 22 is fixed on a rotating support 251. The tilt angle of the water distribution membrane 22 is adjusted by the rotating shaft 252 and the rotating support 251 to better receive light and allow droplets on the water distribution membrane 22 to carry the product away from its surface. After the reaction is complete, the pressure is released and the gas is released. Finally, the valve is opened to discharge the liquid product, thereby realizing the recovery and reuse of methanol and formic acid in the effluent after conversion. The released gas can be temporarily stored in the gas storage tank 243 and then returned to the spray inlet area 11 to remove dissolved organic matter through spraying.

[0100] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for converting gases in a municipal solid waste landfill, characterized in that: include: Step 1: Spray the gas from the municipal solid waste landfill to remove particulate matter and soluble gases, and then perform gas separation on the sprayed gas to separate the target gas. Step 2: The target gas is introduced into the reaction chamber of an intermittent reaction unit, and the gas pressure inside the reaction chamber is less than or equal to 30 MPa; the target gas entering the reaction chamber is mixed with air through gas distribution, and when the target gas is methane, the volume ratio of methane to oxygen is 1:1~100; simultaneously, water is injected into a water distribution membrane evenly distributed in the reaction chamber; the water distribution membrane has multiple layers, which are spaced apart in the vertical direction; several nanoscale water-permeable pores are evenly distributed on the water distribution membrane, and the openings of the nanoscale water-permeable pores are located on the lower surface of the water distribution membrane; the water distribution membrane is loaded with metal particles for catalysis, and the metal particles are at least distributed on the lower surface of the water distribution membrane and at each nanoscale water-permeable pore; the metal particles in the water distribution membrane are transition metal particles; Step 3: Irradiate the reaction chamber to allow the nanodroplets that have seeped out of the water distribution membrane to undergo a photocatalytic reaction with the target gas in the reaction chamber, thereby converting the target gas. The wavelength range of the light source used for irradiation is from ultraviolet to visible light. The light rays form an angle with the lower surface of the water distribution membrane, and the angle range is 5~45°.

2. The method for converting gases in a municipal solid waste landfill according to claim 1, characterized in that: Also includes: Step 4: The converted gas is returned to Step 1 through pipelines for recycling, while the liquid produced after conversion is recovered.

3. The method for converting gases in a municipal solid waste landfill according to claim 1, characterized in that: In step one, the sprayed gas is first demisted and dried before gas separation.

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