垃圾在焚燒過程中，會產生大量滲濾液（每噸垃圾約產生0.5-1噸滲濾液）。滲濾液通過厭氧發(fā)酵可產生沼氣，其主要成分為甲烷（CH?，約50%-70%）、二氧化碳（CO?，約30%-50%）及少量硫化氫（H?S）、氨氮等雜質。沼氣提純是將沼氣中的雜質去除，使甲烷純度提升至95%以上（達到天然氣標準），從而實現(xiàn)“變廢為寶”。對于垃圾焚燒發(fā)電廠而言，沼氣提純不僅能減少溫室氣體排放、提升能源利用效率，還能拓展循環(huán)經濟鏈條（如將提純后的生物天然氣并入管網、制備CNG/LNG，或與焚燒發(fā)電的余熱利用結合），符合“雙碳”目標下的綠色發(fā)展要求。垃圾焚燒發(fā)電廠沼氣提純的核心技術

　　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

　　沼氣提純的本質是分離雜質氣體（CO?、H?S）與甲烷，目前主流技術包括膜分離法、變壓吸附法（PSA）、化學吸收法（胺洗）及水洗法，其中膜分離法因模塊化、低能耗、易維護等優(yōu)勢，在垃圾焚燒發(fā)電廠中應用最為廣泛。

　　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.?膜分離法：精準分離，高效提純膜分離法的核心是利用不同氣體在膜中的滲透速率差異，實現(xiàn)雜質與甲烷的分離。其原理為：沼氣經預處理（除塵、脫水、脫硫）后，進入膜組件，其中CO?、H?S等小分子雜質因滲透速率快，優(yōu)先透過膜進入滲透側；甲烷因滲透速率慢，留在截留側，從而獲得高純度甲烷（CH?≥95%）。技術優(yōu)勢：①高純度：超選擇性分離膜可使甲烷純度穩(wěn)定達97%以上，直接滿足《天然氣》（GB17820-2018）標準，可并入天然氣管網或作為車用燃氣（CNG/LNG）；②低能耗：僅需少量壓縮動力（電耗約0.3-0.5 kWh/m?沼氣），運行成本低；③易維護：模塊化設計（即插即用），可根據產能需求靈活擴展；耐腐蝕材料（如聚酰亞胺）適應沼氣復雜成分（如H?S、氨氮），設備壽命延長至8-10年；④環(huán)保性：尾氣（滲透側的CO?）可回收用于農業(yè)（如大棚氣肥）或工業(yè)（如碳酸飲料生產），實現(xiàn)“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.?變壓吸附法（PSA）：智能化調控，能耗降低PSA法利用吸附劑（如活性炭、分子篩）對不同氣體的選擇性吸附，實現(xiàn)雜質分離。其原理為：沼氣在高壓下進入吸附塔，CO?、H?S等雜質被吸附劑吸附，甲烷則透過吸附劑，從塔頂排出；當吸附劑飽和后，降低壓力（或通入惰性氣體），吸附的雜質脫附，吸附劑再生，循環(huán)使用。技術優(yōu)勢：①智能化：AI動態(tài)調節(jié)分離壓力、溫度參數(shù)，減少能耗浪費（能耗降低30%）；②高回收率：甲烷回收率可達96%以上，適合大規(guī)模處理（如1000Nm?/h以上）；③易擴展：模塊化設計，可根據產能需求增加吸附塔數(shù)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化學吸收法（胺洗）：傳統(tǒng)技術，適合高濃度CO?胺洗法利用胺液（如MEA、DEA）與CO?的化學反應，實現(xiàn)雜質分離。其原理為：沼氣進入吸收塔，與胺液逆流接觸，CO?與胺液反應生成氨基甲酸鹽，留在液相中；甲烷則從塔頂排出，進入凈化側；當胺液飽和后，進入再生塔，加熱分解氨基甲酸鹽，釋放CO?，胺液再生，循環(huán)使用。技術優(yōu)勢：①高純度：甲烷純度可達99%以上，適合對純度要求極高的場景（如電子工業(yè)）；②適合高濃度CO?：當沼氣中CO?含量超過50%時，胺洗法的能耗低于膜分離法。應用局限：①高能耗：再生塔需要加熱，能耗較高（電耗約0.6-0.8 kWh/m?沼氣）；②易腐蝕：胺液對設備有腐蝕作用，需要采用耐腐蝕材料（如不銹鋼）；③維護頻繁：胺液需要定期更換，維護成本高。

　　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、垃圾焚燒發(fā)電廠沼氣提純的工藝流程

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

　　垃圾焚燒發(fā)電廠沼氣提純的典型工藝流程可分為預處理→脫硫→脫碳→深度凈化→壓縮/液化五個環(huán)節(jié)，具體如下：1、預處理：去除雜質，保障后續(xù)工藝預處理的目的是去除沼氣中的粉塵、水分、油滴等雜質，防止后續(xù)設備（如膜組件、吸附塔）堵塞或腐蝕。主要步驟包括：除塵：通過旋風分離器、布袋除塵器去除沼氣中的粉塵（顆粒直徑＞5μm）；脫水：通過冷卻器（降低沼氣溫度至露點以下）或吸附劑（如分子篩）去除水分（露點降至-40℃以下）；除油：通過油水分離器去除沼氣中的油滴（來自滲濾液厭氧發(fā)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、脫硫：去除H?S，防止腐蝕H?S是沼氣中的主要腐蝕性雜質，會腐蝕管道、設備（如發(fā)動機、膜組件），同時會污染環(huán)境（產生酸雨）。脫硫方法包括：化學脫硫：如三氧化二鐵吸附法（H?S與Fe?O?反應生成FeS），適合低濃度H?S（＜1000ppm）；生物脫硫：利用微生物（如脫硫細菌）將H?S氧化為單質硫，適合高濃度H?S（＞1000ppm），且環(huán)保無二次污染。

　　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.?脫碳：去除CO?，提升甲烷純度脫碳是沼氣提純的核心環(huán)節(jié)，主要方法包括膜分離法、PSA法、胺洗法（詳見第二部分）。其中，膜分離法因低能耗、易維護，是垃圾焚燒發(fā)電廠的首選。

　　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.?深度凈化：去除微量雜質，滿足天然氣標準深度凈化的目的是去除沼氣中的微量O?、N?、VOCs（揮發(fā)性有機物）等雜質，使甲烷純度達到《天然氣》（GB17820-2018）標準（CH?≥95%，O?≤0.5%，N?≤2%）。主要方法包括：脫氧：利用催化加氫（H?與O?反應生成H?O）或吸附法（如鈀分子篩）去除O?；脫氮：利用膜分離法（N?的滲透速率快于CH?）或PSA法去除N?；VOCs處理：利用活性炭吸附或催化燃燒去除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.?壓縮/液化：便于儲存與運輸提純后的生物天然氣（BM）若要并入天然氣管網，需壓縮至中壓（0.4-0.8MPa）；若要作為車用燃氣（CNG/LNG），需進一步壓縮至20-25MPa（CNG）或液化至-162℃（LNG）。壓縮/液化后的生物天然氣可通過管網輸送至用戶（如居民、工業(yè)）或運輸至加氣站（如CNG加氣站）。

　　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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