碳中和的實質(zhì)問題是能源的問題，根據(jù)貫徹“綠水青山就是金山銀山”的理念，國務(wù)院在2021年10月發(fā)布了《關(guān)于2030年前碳達峰行動方案的通知》明確了行動方案。作為清潔能源的替代品生物質(zhì)天然和可再生氫能作為重要組成部分擺在了所有環(huán)衛(wèi)設(shè)施建設(shè)人的面前。如何選擇這兩種能源是項目建設(shè)的關(guān)鍵問題，也是實現(xiàn)碳達峰落地的實質(zhì)性問題。以實際項目案例進行沼氣制生物天然氣和可再生氫能對比，對其他項目選擇做出參考。

　　The essence of carbon neutrality lies in the issue of energy. In accordance with the concept of "green mountains and clear waters are as valuable as mountains of gold and silver", the State Council issued the "Notice on the Action Plan for Carbon Peak before 2030" in October 2021, which clarified the action plan. Biomass natural and renewable hydrogen energy, as an important component of clean energy alternatives, are placed in front of all sanitation facility builders. How to choose these two types of energy is a key issue in project construction and a substantive issue in achieving carbon peak implementation. Compare biogas to biogas and renewable hydrogen energy through actual project cases, and provide reference for the selection of other projects.

　　1 前言

　　1 Preface

　　天然氣和氫氣均被認定為清潔能源，我國在當前主要是使用煤炭、石油作為能源，也是第一大碳排放的原料。為了實現(xiàn)碳達峰、碳中和，需要加快使用清潔能源替代傳統(tǒng)能源。我國承諾在2030年實現(xiàn)碳達峰，主要途徑是對產(chǎn)業(yè)結(jié)構(gòu)、能源結(jié)構(gòu)進行調(diào)整。在2060年實現(xiàn)碳中和，主要是通過能源過程、工業(yè)生產(chǎn)過程、農(nóng)業(yè)、土地利用等全口徑全流程實現(xiàn)零排放。我國承諾實現(xiàn)上述目標的時間遠遠短于發(fā)達國家所用的時間，做出的努力必將遠遠大于這些國家。同樣作為可再生能源和清潔能源，國家相關(guān)部委從2019年至今一直密集發(fā)布天然氣和氫氣作為可再生能源產(chǎn)業(yè)的指導意見。國家發(fā)改委等10大部委在2019年發(fā)布《關(guān)于促進生物天然氣產(chǎn)業(yè)化發(fā)展的指導意見》中要求構(gòu)建生物天然氣發(fā)展規(guī)劃體系，組織編制生物天然氣中長期發(fā)展規(guī)劃。而2022年國家發(fā)改委和能源局聯(lián)合研究制定《氫能產(chǎn)業(yè)發(fā)展中長期規(guī)劃（2021~2035年）》“十四五”時期，我國將初步建立以工業(yè)副產(chǎn)氫和可再生能源制氫就近利用為主的氫能供應(yīng)體系。同樣的產(chǎn)業(yè)發(fā)展指導意見和發(fā)展規(guī)劃，均明確了無論是生物天然氣還是氫能作為可再生能源的屬性。目前可再生能源主要原材料為農(nóng)作物秸稈、畜禽糞污、城市餐飲垃圾、城市生活垃圾填埋場等。結(jié)合目前我國實行的生活垃圾分類收集處置的方針，規(guī)模化和產(chǎn)業(yè)化的生物天然氣主要來源是城市濕垃圾處理設(shè)施。

　　Natural gas and hydrogen are both recognized as clean energy sources. Currently, China mainly uses coal and oil as energy sources, which are also the largest sources of carbon emissions. In order to achieve carbon peak and carbon neutrality, it is necessary to accelerate the use of clean energy to replace traditional energy. China has committed to achieving carbon peak by 2030, mainly through adjusting its industrial and energy structure. To achieve carbon neutrality by 2060, the main approach is to achieve zero emissions through a full range of processes including energy, industrial production, agriculture, and land use. Our country's commitment to achieving the above goals is much shorter than the time taken by developed countries, and the efforts made will undoubtedly be much greater than those of these countries. As both renewable and clean energy sources, relevant national departments have been intensively issuing guidance on natural gas and hydrogen as renewable energy industries since 2019. In 2019, the National Development and Reform Commission and 10 other ministries issued the "Guiding Opinions on Promoting the Industrialization Development of Bionatural Gas", which required the construction of a development planning system for biogas and the organization of the preparation of medium - and long-term development plans for biogas. In 2022, the National Development and Reform Commission and the Energy Administration jointly studied and formulated the "Medium - and Long Term Plan for the Development of the Hydrogen Energy Industry (2021-2025)". During the 14th Five Year Plan period, China will initially establish a hydrogen energy supply system mainly based on the nearby utilization of industrial by-product hydrogen and renewable energy hydrogen production. The same industry development guidance and development plan have clearly defined the attributes of both biogas and hydrogen as renewable energy sources. At present, the main raw materials for renewable energy are crop straw, livestock and poultry manure, urban catering waste, and urban household waste landfills. Based on the current policy of classified collection and disposal of household waste in China, the main source of large-scale and industrialized biogas is urban wet waste treatment facilities.

　　2 項目情況介紹

　　Introduction to Project 2

　　位于某市的濕垃圾處理項目，處理規(guī)模為500噸/日，其中廚余垃圾300t/d，餐飲垃圾200t/d。主要工藝采用厭氧發(fā)酵方式產(chǎn)生沼氣。經(jīng)過計算沼氣量約為32000m3/d，這些沼氣是經(jīng)過厭氧發(fā)酵產(chǎn)生，主要成分是CH4、CO2和H2S。沼氣的成分如表1所示：

　　The wet waste treatment project located in a certain city has a processing capacity of 500 tons/day, including 300t/d of kitchen waste and 200t/d of catering waste. The main process uses anaerobic fermentation to produce biogas. After calculation, the amount of biogas is about 32000m3/d. These biogas are produced through anaerobic fermentation and mainly consist of CH4, CO2, and H2S. The composition of biogas is shown in Table 1:

　　分析后可以看出，經(jīng)過厭氧發(fā)酵后的沼氣在熱值、華白指數(shù)等指標，與我國現(xiàn)行國標天然氣相差甚遠，不能直接輸送至天然氣管道。需要對CO2、O2以及其他雜質(zhì)進行脫除。

　　After analysis, it can be seen that the biogas produced by anaerobic fermentation has a significant difference in calorific value, Huabai index and other indicators compared to the current national standard for natural gas in China, and cannot be directly transported to natural gas pipelines. CO2, O2, and other impurities need to be removed.

　　3 生物質(zhì)天然氣工藝流程及產(chǎn)品指標

　　3. Biomass natural gas process flow and product indicators

　　前端工藝產(chǎn)生的沼氣進入氣柜儲存、均質(zhì)、穩(wěn)壓，穩(wěn)壓后經(jīng)沼氣風機升壓至20~25kPa后送入濕法脫硫系統(tǒng)將硫化氫脫至50mg/m3以下。濕法脫硫后氣體含大量水分，經(jīng)氣液分離之后送入干法脫硫系統(tǒng)將硫化氫脫至10mg/Nm3以內(nèi)。脫硫后沼氣經(jīng)預處理系統(tǒng)除塵、除水、調(diào)溫后，由沼氣壓縮機增壓至變壓吸附工作壓力0.5MPa。壓縮后沼氣經(jīng)除油、除水后進入揮發(fā)性有機化合物（VOC）脫除塔吸附除臭，進一步預處理凈化原料氣。原料氣最終進入變壓吸附裝置進行脫碳精制，精制得到的天然氣產(chǎn)品經(jīng)調(diào)壓計量及加臭后送入市政燃氣管網(wǎng)。變壓吸附順放氣高壓部分順放至沼氣螺桿壓縮機，低壓部分順放至預處理沼氣羅茨風機入口，吸附提純解析氣部分回流至沼氣羅茨風機入口，其余大部分解析氣送至火炬系統(tǒng)燃燒或直接排空。具體工藝流程如圖1生物質(zhì)天然氣工程流程圖和表2生物質(zhì)天然氣指標表所示。

　　The biogas generated by the front-end process enters the gas holder for storage, homogenization, and stabilization. After stabilization, it is pressurized to 20-25kPa by the biogas fan and sent to the wet desulfurization system to remove hydrogen sulfide to below 50mg/m3. After wet desulfurization, the gas contains a large amount of moisture. After gas-liquid separation, it is sent to the dry desulfurization system to remove hydrogen sulfide to less than 10mg/Nm3. After desulfurization, the biogas is subjected to dust removal, water removal, and temperature regulation through a pretreatment system, and then pressurized by a biogas compressor to a pressure swing adsorption working pressure of 0.5 MPa. After compression, the biogas enters the volatile organic compound (VOC) removal tower for adsorption and deodorization after oil and water removal, and further pretreats and purifies the raw gas. The raw gas ultimately enters the pressure swing adsorption unit for decarbonization and refining. The refined natural gas product is regulated, metered, and odorized before being sent to the municipal gas pipeline network. The high-pressure part of the pressure swing adsorption gas is discharged to the biogas screw compressor, the low-pressure part is discharged to the inlet of the pre-treatment biogas Roots blower, the adsorption and purification gas is refluxed to the inlet of the biogas Roots blower, and the rest of the gas is sent to the flare system for combustion or directly discharged. The specific process flow is shown in Figure 1 Biomass Natural Gas Engineering Flow Chart and Table 2 Biomass Natural Gas Index Table.

　　4 氫氣工藝流程及產(chǎn)品指標

　　4 Hydrogen process flow and product indicators

　　工藝流程由制氫裝置和二氧化碳液化裝置組成。制氫裝置以沼氣為原料，采用的工藝路線為沼氣濕法甲基二乙醇胺（MDEA）脫碳→蒸汽轉(zhuǎn)化→合成氣濕法MDEA脫碳→變壓吸附（PSA）分離得到產(chǎn)品氫氣。二氧化碳液化裝置以制氫裝置中產(chǎn)生的二氧化碳尾氣作為原料，采用的工藝路線為CO2壓縮→預冷卻→分子篩干燥/凈化→液化精餾得到食品級CO2產(chǎn)品。工藝流程如圖2PSA制氫工藝流程圖和表3產(chǎn)品氫氣指標表所示。

　　The process flow consists of a hydrogen production unit and a carbon dioxide liquefaction unit. The hydrogen production unit uses biogas as the raw material and adopts the process route of wet process of methane based methylenediethanolamine (MDEA) decarbonization → steam reforming → synthesis gas wet MDEA decarbonization → pressure swing adsorption (PSA) separation to obtain product hydrogen. The carbon dioxide liquefaction unit uses the carbon dioxide tail gas generated in the hydrogen production unit as raw material, and adopts the process route of CO2 compression → pre cooling → molecular sieve drying/purification → liquefaction distillation to obtain food grade CO2 products. The process flow is shown in Figure 2PSA hydrogen production process flow chart and Table 3 product hydrogen index table.

　　5 方案對比

　　Comparison of 5 Plans

　　從濕垃圾處理項目本身作為市政基礎(chǔ)的穩(wěn)定運行考慮，對沼氣制天然氣和氫氣從安全性、經(jīng)濟性進行比較。首先我們對天然氣和氫氣在物化性質(zhì)與危險特性進行對比，詳見表4天然氣和氫氣的物化性質(zhì)與危險特性對比表。從特比可以看出，氫氣的爆炸極限遠大于天然氣。同時氫氣在遇到超過400℃的熱源或明火后會爆炸，與天然氣比較有較大的活性。在中等規(guī)模項目中較難控制。

　　Considering the stable operation of the wet waste treatment project as a municipal foundation, a comparison is made between the safety and economy of biogas to natural gas and hydrogen production. Firstly, we compare the physicochemical properties and hazardous characteristics of natural gas and hydrogen, as shown in Table 4. From the comparison, it can be seen that the explosive limit of hydrogen is much greater than that of natural gas. At the same time, hydrogen gas will explode when exposed to heat sources or open flames above 400 ℃, and has greater activity compared to natural gas. Difficult to control in medium-sized projects.

　　從項目本身的經(jīng)濟性進行比較，如表5所示為生物質(zhì)天然氣與制氫經(jīng)濟比較：考慮本項目選址的周邊條件考慮。項目選址附近有市政天然氣管道，可以加壓后直接輸送。而氫氣輸送有兩種方法，分別是與天然氣并網(wǎng)輸送和加壓至20MPa采用拖車運輸。第一種與天然氣并網(wǎng)輸送技術(shù)并不成熟，而采用加壓后拖車運輸費用較高。根據(jù)上述比較，本項目最終選擇厭氧發(fā)酵沼氣PSA工藝制生物質(zhì)天然氣。

　　Comparing the economic viability of the project itself, Table 5 shows the economic comparison between biomass natural gas and hydrogen production: taking into account the surrounding conditions of the project site selection. There is a municipal natural gas pipeline near the project site, which can be pressurized and directly transported. There are two methods for hydrogen transportation, namely grid connected transportation with natural gas and trailer transportation when pressurized to 20MPa. The first type of grid connected transportation technology for natural gas is not yet mature, and the cost of using pressurized trailer transportation is relatively high. Based on the above comparison, this project ultimately chooses the anaerobic fermentation biogas PSA process to produce biomass natural gas.

　　6 結(jié)束語

　　6 Conclusion

　　碳達峰、碳中和的目標是可再生能源的革命，同時推動能源結(jié)構(gòu)多元化進程。在生物質(zhì)能源中利用厭氧技術(shù)產(chǎn)生的生物質(zhì)氣體作為可再生能源回收利用，是可循環(huán)經(jīng)濟的重要議題之一。然而在相關(guān)配套設(shè)施上仍然存在差距，如相較于天然氣管道，氫氣管道配套建設(shè)仍不完善，目前國內(nèi)仍沒有適用于氫氣長輸管道的設(shè)計、建造和驗收標準。需要加快對于氫氣產(chǎn)業(yè)的終端用戶的扶持力度，如氫能汽車等。生物質(zhì)可再生能源取代傳統(tǒng)化石能源是必然之路，對于節(jié)能減排的效果立竿見影。

　　The goal of peaking carbon emissions and achieving carbon neutrality is a revolution in renewable energy, while promoting the diversification of energy structure. The utilization of biomass gas generated by anaerobic technology in biomass energy as a renewable energy source for recycling is one of the important issues in the circular economy. However, there are still gaps in related supporting facilities, such as the incomplete construction of hydrogen pipelines compared to natural gas pipelines. Currently, there are no design, construction, and acceptance standards applicable to hydrogen long-distance pipelines in China. We need to accelerate support for end-users in the hydrogen industry, such as hydrogen powered vehicles. The replacement of traditional fossil fuels with renewable biomass energy is an inevitable path, which has an immediate effect on energy conservation and emission reduction.

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