垃圾在焚烧过程中，会产生大量渗滤液（每吨垃圾约产生0.5-1吨渗滤液）。渗滤液通过厌氧发酵可产生沼气，其主要成分为甲烷（CH?，约50%-70%）、二氧化碳（CO?，约30%-50%）及少量硫化氢（H?S）、氨氮等杂质。沼气提纯是将沼气中的杂质去除，使甲烷纯度提升至95%以上（达到天然气标准），从而实现“变废为宝”。对于垃圾焚烧发电厂而言，沼气提纯不仅能减少温室气体排放、提升能源利用效率，还能拓展循环经济链条（如将提纯后的生物天然气并入管网、制备CNG/LNG，或与焚烧发电的余热利用结合），符合“双碳”目标下的绿色发展要求。垃圾焚烧发电厂沼气提纯的核心技术

　　During the incineration process of garbage, a large amount of leachate is generated (approximately 0.5-1 ton of leachate per ton of garbage). Leachate can produce biogas through anaerobic fermentation, which is mainly composed of methane (CH ?, about 50% -70%), carbon dioxide (CO ?, about 30% -50%), and a small amount of impurities such as hydrogen sulfide (H ? S) and ammonia nitrogen. Biogas purification is the process of removing impurities from biogas to increase methane purity to over 95% (meeting natural gas standards), thereby achieving the goal of "turning waste into treasure". For waste incineration power plants, biogas purification can not only reduce greenhouse gas emissions and improve energy efficiency, but also expand the circular economy chain (such as integrating purified biogas into pipelines, preparing CNG/LNG, or combining it with waste heat utilization from incineration power generation), which meets the green development requirements under the "dual carbon" goal. Core technology for biogas purification in waste incineration power plants

　　沼气提纯的本质是分离杂质气体（CO?、H?S）与甲烷，目前主流技术包括膜分离法、变压吸附法（PSA）、化学吸收法（胺洗）及水洗法，其中膜分离法因模块化、低能耗、易维护等优势，在垃圾焚烧发电厂中应用最为广泛。

　　The essence of biogas purification is to separate impurity gases (CO ?, H ? S) from methane. Currently, mainstream technologies include membrane separation, pressure swing adsorption (PSA), chemical absorption (amine washing), and water washing. Among them, membrane separation is the most widely used in waste incineration power plants due to its advantages of modularity, low energy consumption, and easy maintenance.

　　1.?膜分离法：精准分离，高效提纯膜分离法的核心是利用不同气体在膜中的渗透速率差异，实现杂质与甲烷的分离。其原理为：沼气经预处理（除尘、脱水、脱硫）后，进入膜组件，其中CO?、H?S等小分子杂质因渗透速率快，优先透过膜进入渗透侧；甲烷因渗透速率慢，留在截留侧，从而获得高纯度甲烷（CH?≥95%）。技术优势：①高纯度：超选择性分离膜可使甲烷纯度稳定达97%以上，直接满足《天然气》（GB17820-2018）标准，可并入天然气管网或作为车用燃气（CNG/LNG）；②低能耗：仅需少量压缩动力（电耗约0.3-0.5 kWh/m?沼气），运行成本低；③易维护：模块化设计（即插即用），可根据产能需求灵活扩展；耐腐蚀材料（如聚酰亚胺）适应沼气复杂成分（如H?S、氨氮），设备寿命延长至8-10年；④环保性：尾气（渗透侧的CO?）可回收用于农业（如大棚气肥）或工业（如碳酸饮料生产），实现“零排放”。

　　1. Membrane separation method: precise separation and efficient purification. The core of membrane separation method is to use the difference in permeation rate of different gases in the membrane to achieve the separation of impurities and methane. The principle is that after pre-treatment (dust removal, dehydration, desulfurization), biogas enters the membrane module, where small molecule impurities such as CO ? and H ? S preferentially penetrate the membrane and enter the permeate side due to their fast permeation rate; Methane remains on the interception side due to its slow permeation rate, resulting in high-purity methane (CH ? ≥ 95%). Technical advantages: ① High purity: The ultra selective separation membrane can stabilize methane purity to over 97%, directly meeting the standards of "Natural Gas" (GB17820-2018), and can be integrated into natural gas pipelines or used as automotive gas (CNG/LNG); ② Low energy consumption: only requires a small amount of compression power (electricity consumption of about 0.3-0.5 kWh/m ? biogas), with low operating costs; ③ Easy to maintain: modular design (plug and play), flexible expansion according to production capacity requirements; Corrosion resistant materials (such as polyimide) are suitable for complex components of biogas (such as H ? S, ammonia nitrogen), and the equipment life is extended to 8-10 years; ④ Environmental friendliness: The exhaust gas (CO ? on the permeate side) can be recycled for use in agriculture (such as greenhouse gas fertilizer) or industry (such as carbonated beverage production), achieving "zero emissions".

　　2.?变压吸附法（PSA）：智能化调控，能耗降低PSA法利用吸附剂（如活性炭、分子筛）对不同气体的选择性吸附，实现杂质分离。其原理为：沼气在高压下进入吸附塔，CO?、H?S等杂质被吸附剂吸附，甲烷则透过吸附剂，从塔顶排出；当吸附剂饱和后，降低压力（或通入惰性气体），吸附的杂质脱附，吸附剂再生，循环使用。技术优势：①智能化：AI动态调节分离压力、温度参数，减少能耗浪费（能耗降低30%）；②高回收率：甲烷回收率可达96%以上，适合大规模处理（如1000Nm?/h以上）；③易扩展：模块化设计，可根据产能需求增加吸附塔数量。

　　2. Pressure swing adsorption (PSA): Intelligent regulation and energy reduction. PSA uses adsorbents (such as activated carbon and molecular sieves) to selectively adsorb different gases, achieving impurity separation. The principle is that biogas enters the adsorption tower under high pressure, impurities such as CO ? and H ? S are adsorbed by the adsorbent, and methane passes through the adsorbent and is discharged from the top of the tower; When the adsorbent is saturated, reduce the pressure (or introduce inert gas), desorb the adsorbed impurities, regenerate the adsorbent, and recycle it. Technical advantages: ① Intelligence: AI dynamically adjusts separation pressure and temperature parameters, reducing energy consumption and waste (energy consumption reduced by 30%); ② High recovery rate: The methane recovery rate can reach over 96%, suitable for large-scale processing (such as over 1000Nm ?/h); ③ Easy to expand: modular design, can increase the number of adsorption towers according to production capacity requirements.

　　3化学吸收法（胺洗）：传统技术，适合高浓度CO?胺洗法利用胺液（如MEA、DEA）与CO?的化学反应，实现杂质分离。其原理为：沼气进入吸收塔，与胺液逆流接触，CO?与胺液反应生成氨基甲酸盐，留在液相中；甲烷则从塔顶排出，进入净化侧；当胺液饱和后，进入再生塔，加热分解氨基甲酸盐，释放CO?，胺液再生，循环使用。技术优势：①高纯度：甲烷纯度可达99%以上，适合对纯度要求极高的场景（如电子工业）；②适合高浓度CO?：当沼气中CO?含量超过50%时，胺洗法的能耗低于膜分离法。应用局限：①高能耗：再生塔需要加热，能耗较高（电耗约0.6-0.8 kWh/m?沼气）；②易腐蚀：胺液对设备有腐蚀作用，需要采用耐腐蚀材料（如不锈钢）；③维护频繁：胺液需要定期更换，维护成本高。

　　3. Chemical absorption method (amine washing): Traditional technology suitable for high concentration CO ? amine washing method utilizes the chemical reaction between amine solution (such as MEA, DEA) and CO ? to achieve impurity separation. The principle is as follows: biogas enters the absorption tower and comes into countercurrent contact with the amine solution. CO ? reacts with the amine solution to form aminoformate, which remains in the liquid phase; Methane is discharged from the top of the tower and enters the purification side; When the amine solution is saturated, it enters the regeneration tower and is heated to decompose the amino formate salt, releasing CO ?. The amine solution is regenerated and recycled. Technical advantages: ① High purity: Methane purity can reach over 99%, suitable for scenarios with extremely high purity requirements (such as the electronics industry); ② Suitable for high concentration CO ?: When the CO ? content in biogas exceeds 50%, the energy consumption of amine washing method is lower than that of membrane separation method. Application limitations: ① High energy consumption: The regeneration tower requires heating, resulting in high energy consumption (approximately 0.6-0.8 kWh/m ? of biogas); ② Corrosion prone: Amine solution has a corrosive effect on equipment and requires the use of corrosion-resistant materials (such as stainless steel); ③ Frequent maintenance: Amine solution needs to be replaced regularly, resulting in high maintenance costs.

　　三、垃圾焚烧发电厂沼气提纯的工艺流程

　　3、 Process flow of biogas purification in garbage incineration power plants

　　垃圾焚烧发电厂沼气提纯的典型工艺流程可分为预处理→脱硫→脱碳→深度净化→压缩/液化五个环节，具体如下：1、预处理：去除杂质，保障后续工艺预处理的目的是去除沼气中的粉尘、水分、油滴等杂质，防止后续设备（如膜组件、吸附塔）堵塞或腐蚀。主要步骤包括：除尘：通过旋风分离器、布袋除尘器去除沼气中的粉尘（颗粒直径＞5μm）；脱水：通过冷却器（降低沼气温度至露点以下）或吸附剂（如分子筛）去除水分（露点降至-40℃以下）；除油：通过油水分离器去除沼气中的油滴（来自渗滤液厌氧发酵的浮油）

　　The typical process flow of biogas purification in garbage incineration power plants can be divided into five stages: pretreatment → desulfurization → decarbonization → deep purification → compression/liquefaction. Specifically, the following steps are taken: 1. pretreatment: removing impurities to ensure the removal of dust, moisture, oil droplets and other impurities in the biogas, and to prevent subsequent equipment (such as membrane components and adsorption towers) from clogging or corrosion. The main steps include: dust removal: removing dust (particle diameter>5 μ m) from biogas through cyclone separator and bag filter; Dehydration: Remove moisture (dew point below -40 ℃) through a cooler (reducing biogas temperature to below dew point) or adsorbent (such as molecular sieve); Oil removal: Remove oil droplets from biogas (floating oil from anaerobic fermentation of leachate) through an oil-water separator

　　2、脱硫：去除H?S，防止腐蚀H?S是沼气中的主要腐蚀性杂质，会腐蚀管道、设备（如发动机、膜组件），同时会污染环境（产生酸雨）。脱硫方法包括：化学脱硫：如三氧化二铁吸附法（H?S与Fe?O?反应生成FeS），适合低浓度H?S（＜1000ppm）；生物脱硫：利用微生物（如脱硫细菌）将H?S氧化为单质硫，适合高浓度H?S（＞1000ppm），且环保无二次污染。

　　2. Desulfurization: Remove H ? S and prevent corrosion. H ? S is the main corrosive impurity in biogas, which can corrode pipelines, equipment (such as engines and membrane components), and pollute the environment (producing acid rain). The desulfurization methods include: chemical desulfurization, such as the ferric oxide adsorption method (where H ? S reacts with Fe ? O3 to form FeS), suitable for low concentrations of H ? S (<1000ppm); Biological desulfurization: using microorganisms (such as desulfurization bacteria) to oxidize H ? S into elemental sulfur, suitable for high concentrations of H ? S (>1000ppm), and environmentally friendly without secondary pollution.

　　3.?脱碳：去除CO?，提升甲烷纯度脱碳是沼气提纯的核心环节，主要方法包括膜分离法、PSA法、胺洗法（详见第二部分）。其中，膜分离法因低能耗、易维护，是垃圾焚烧发电厂的首选。

　　3. Decarbonization: Removing CO ? and improving methane purity. Decarbonization is the core process of biogas purification, and the main methods include membrane separation, PSA, and amine washing (see Part 2 for details). Among them, membrane separation method is the preferred choice for waste incineration power plants due to its low energy consumption and easy maintenance.

　　4.?深度净化：去除微量杂质，满足天然气标准深度净化的目的是去除沼气中的微量O?、N?、VOCs（挥发性有机物）等杂质，使甲烷纯度达到《天然气》（GB17820-2018）标准（CH?≥95%，O?≤0.5%，N?≤2%）。主要方法包括：脱氧：利用催化加氢（H?与O?反应生成H?O）或吸附法（如钯分子筛）去除O?；脱氮：利用膜分离法（N?的渗透速率快于CH?）或PSA法去除N?；VOCs处理：利用活性炭吸附或催化燃烧去除VOCs（如苯、甲苯）。

　　4. Deep purification: Removing trace impurities to meet natural gas standards. The purpose of deep purification is to remove trace impurities such as O ?, N ?, VOCs (volatile organic compounds) in biogas, so that the methane purity meets the standards of "Natural Gas" (GB17820-2018) (CH ? ≥ 95%, O ? ≤ 0.5%, N ? ≤ 2%). The main methods include: deoxygenation: using catalytic hydrogenation (H ? reacts with O ? to generate H ? O) or adsorption methods (such as palladium molecular sieves) to remove O ?; Denitrification: using membrane separation method (N ? has a faster permeation rate than CH ?) or PSA method to remove N ?; VOCs treatment: using activated carbon adsorption or catalytic combustion to remove VOCs (such as benzene and toluene).

　　5.?压缩/液化：便于储存与运输提纯后的生物天然气（BM）若要并入天然气管网，需压缩至中压（0.4-0.8MPa）；若要作为车用燃气（CNG/LNG），需进一步压缩至20-25MPa（CNG）或液化至-162℃（LNG）。压缩/液化后的生物天然气可通过管网输送至用户（如居民、工业）或运输至加气站（如CNG加气站）。

　　5. Compression/liquefaction: For the storage and transportation of purified bio natural gas (BM), if it is to be integrated into the natural gas pipeline network, it needs to be compressed to medium pressure (0.4-0.8MPa); To be used as automotive gas (CNG/LNG), it needs to be further compressed to 20-25MPa (CNG) or liquefied to -162 ℃ (LNG). Compressed/liquefied biogas can be transported to users (such as residents and industries) or to gas stations (such as CNG filling stations) through pipelines.

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