厌氧消化是我国解决污泥处理处置的一条重要技术路线，在污泥消化过程中有机固体降解的同时，也伴随产生了沼气。沼气是一种混合气体，一般情况下所含CH4体积分数为60%～70%、CO2为30%～40%，还含有少量的水汽、H2S、NH3等，其中H2S为剧毒物质，其危害巨大，当空气中的H2S浓度达到0.1%时，会使人立即丧失知觉，导致永久性的脑伤害或脑死亡。沼气中H2S的含量与消化进泥中的含硫量直接相关，我国各地城市污水由于纳入工业废水的种类及占比差异巨大，在已建成的污泥厌氧消化项目中，沼气的H2S含量差别很大，但大多在300～9000mg/m?的范围内，也有个别案例由于消化进泥包含采用Al(2SO4)3混凝剂的初沉化学污泥，沼气中的H2S含量高达30000mg/m?。

　　Anaerobic digestion is an important technical route for sludge treatment and disposal in China. During the sludge digestion process, organic solids are degraded, and biogas is also generated. Biogas is a mixed gas that generally contains 60% to 70% CH4 and 30% to 40% CO2 by volume. It also contains small amounts of water vapor, H2S, NH3, etc. Among them, H2S is a highly toxic substance with enormous harm. When the concentration of H2S in the air reaches 0.1%, it will immediately cause people to lose consciousness, leading to permanent brain injury or death. The content of H2S in biogas is directly related to the sulfur content digested into the sludge. Due to the significant differences in the types and proportions of industrial wastewater included in urban sewage in various regions of China, the H2S content in biogas varies greatly in completed sludge anaerobic digestion projects, but mostly ranges from 300 to 9000 mg/m? Within the scope, there are also individual cases where the digested sludge contains initial settling chemical sludge using Al (2SO4) 3 coagulant, and the H2S content in the biogas is as high as 30000mg/m?.

　　污泥消化所产沼气首先用于满足自身加热的需求(占沼气总产量的25%～50%)，然后用于拖动鼓风机、发电等。但不论是高温还是中温厌氧消化，沼气中均含有饱和水蒸气，随着温度的下降，会形成冷凝液，H2S在这种潮湿的环境下，对金属管道、燃烧设备等具有强烈的腐蚀性;燃烧后产生的SO2，对大气环境造成污染，危害人体健康，从而影响沼气的回收利用。虽然我国尚未有统一完善的沼气作为能源利用时的气质标准，但《大中型沼气工程技术规范》(GB/T51063—2014)对沼气利用时的H2S含量已有规定，即民用集中供气时H2S≤20mg/m?，发电时H2S≤200mg/m?。由于常规污泥消化沼气中的H2S含量远远高于这些要求，所以沼气作为能源利用时，必须进行脱硫处理。

　　The biogas produced by sludge digestion is first used to meet its own heating needs (accounting for 25% to 50% of the total biogas production), and then used to drive blowers, generate electricity, etc. However, whether it is high-temperature or medium temperature anaerobic digestion, biogas contains saturated water vapor, which forms condensate as the temperature decreases. H2S has strong corrosiveness to metal pipelines, combustion equipment, etc. in this humid environment; The SO2 produced after combustion causes pollution to the atmospheric environment, endangers human health, and thus affects the recycling and utilization of biogas. Although there is currently no unified and comprehensive gas quality standard for the use of biogas as an energy source in China, the "Technical Specification for Large and Medium sized Biogas Engineering" (GB/T51063-2014) has already stipulated the H2S content during biogas utilization, that is, H2S ≤ 20mg/m during centralized gas supply for civilian use? H2S ≤ 200mg/m during power generation?. Due to the significantly higher H2S content in conventional sludge digested biogas compared to these requirements, desulfurization treatment is necessary when biogas is used as an energy source.

　　1、国内污泥消化沼气脱硫方法及发展方向主流的沼气脱硫技术包括化学脱硫及生物脱硫两种。前者作为传统的脱硫技术已有百年的历史，被广泛用于硫化氢的去除，且积累了丰富的经验。根据反应介质的固液形态不同，化学脱硫分为干法脱硫和湿法脱硫。

　　1. The mainstream methods and development directions for sludge digestion and biogas desulfurization in China include chemical desulfurization and biological desulfurization. The former, as a traditional desulfurization technology with a history of over a hundred years, has been widely used for the removal of hydrogen sulfide and has accumulated rich experience. According to the different solid-liquid forms of the reaction medium, chemical desulfurization can be divided into dry desulfurization and wet desulfurization.

　　1.1 干法脱硫干法脱硫包括活性炭系、氧化铁系及氧化锌系等，国内在早期的污泥消化项目中应用较多的是常温氧化铁脱硫法。氧化铁脱硫剂多为条状多孔结构固体，对H2S能够进行快速不可逆的化学吸附，数秒内就能将H2S脱除，效率达到99%以上，工作硫容可达到40%，强度达到55N/cm以上。但是对于大型污泥厌氧消化项目，沼气产量大，H2S含量高，氧化铁干法脱硫硫容有限，且传统干法脱硫再生操作易引发单质硫的升华和自燃，安全风险高且卸料劳动强度大，因此，针对大型消化项目，氧化铁干法脱硫不宜作为单级沼气脱硫处理的选择。

　　1.1 Dry desulfurization includes activated carbon, iron oxide, and zinc oxide systems. The ambient temperature iron oxide desulfurization method was widely used in early sludge digestion projects in China. Iron oxide desulfurizers are mostly strip-shaped porous solid structures that can rapidly and irreversibly chemically adsorb H2S. They can remove H2S within seconds with an efficiency of over 99%, a working sulfur capacity of up to 40%, and a strength of over 55N/cm. However, for large-scale anaerobic digestion projects of sludge, the biogas production is large, the H2S content is high, the sulfur capacity of iron oxide dry desulfurization is limited, and the traditional dry desulfurization regeneration operation is prone to sublimation and spontaneous combustion of elemental sulfur, with high safety risks and high unloading labor intensity. Therefore, for large-scale digestion projects, iron oxide dry desulfurization is not suitable as the choice for single-stage biogas desulfurization treatment.

　　1.2 湿法脱硫湿法脱硫是利用特定的溶剂与沼气逆流接触脱除H2S的工艺，根据吸收机理不同，可分为物化吸收和湿式氧化等。该法工艺流程简单，可连续运行，去除效率较高，适宜处理气量大、H2S浓度高的气体。国内市政污水厂污泥消化项目一般体量较大，湿法脱硫有较多的应用。国内消化沼气湿式脱硫多采用碱液吸收法，以氢氧化钠作为吸收液。由于沼气中含有大量的CO2，在碱性溶液中会影响H2S的吸收率，同时受到流速、流量、温度等因素的影响，H2S并不能全部转移到碱液中。事实上，在碱耗为3～5kgNaOH/kgH2S的条件下，H2S只能降至150～500mg/m?。为了提高脱硫效率，需要定期外排脱硫循环液，并对其进行处理，既增加了脱硫成本，也常常带来二次污染。单独采用湿法脱硫，很难直接达到处理要求，同时药剂消耗巨大，相对干法脱硫能耗高且运行管理繁琐，所以高效、经济、低能耗、更先进的脱硫技术成为新的探索目标，而生物脱硫技术为该领域的研究和应用开辟了新的方向。

　　1.2 Wet flue gas desulfurization is a process that uses specific solvents to remove H2S by countercurrent contact with biogas. Depending on the absorption mechanism, it can be divided into physicochemical absorption and wet oxidation. The process flow of this method is simple, can operate continuously, has high removal efficiency, and is suitable for treating gases with large gas volume and high H2S concentration. Domestic municipal sewage treatment plant sludge digestion projects generally have large volumes, and wet desulfurization has many applications. Wet desulfurization of digested biogas in China often adopts alkaline absorption method, using sodium hydroxide as the absorption solution. Due to the high content of CO2 in biogas, it can affect the absorption rate of H2S in alkaline solutions, and is also affected by factors such as flow rate, flow rate, and temperature. H2S cannot be completely transferred to the alkaline solution. In fact, under the condition of alkali consumption of 3-5 kg NaOH/kgH2S, H2S can only be reduced to 150-500mg/m?. In order to improve desulfurization efficiency, it is necessary to regularly discharge desulfurization circulating liquid and treat it, which not only increases desulfurization costs but also often brings about secondary pollution. It is difficult to directly meet the treatment requirements using wet desulfurization alone, and the consumption of chemicals is huge. Compared with dry desulfurization, it has higher energy consumption and more complicated operation and management. Therefore, efficient, economical, low-energy consumption, and more advanced desulfurization technology has become a new exploration goal. Biological desulfurization technology has opened up new directions for research and application in this field.

　　1.3 生物脱硫生物脱硫是20世纪80年代兴起并逐渐成熟的新工艺，利用微生物自身代谢活动将H2S转化为单质硫或硫酸盐最终达到去除H2S的目的。该工艺具有无需催化剂、去除效率高、处理成本低、可回收单质硫等优点，同时能够满足大流量、高H2S浓度的场合，是市政污泥厌氧消化项目可以实现单级解决沼气脱硫问题的理想选择。

　　1.3 Biological desulfurization is a new process that emerged and gradually matured in the 1980s. It utilizes the metabolic activity of microorganisms to convert H2S into elemental sulfur or sulfate, ultimately achieving the goal of removing H2S. This process has the advantages of no catalyst required, high removal efficiency, low treatment cost, and recyclability of elemental sulfur. At the same time, it can meet the requirements of high flow rate and high H2S concentration. It is an ideal choice for municipal sludge anaerobic digestion projects to achieve single-stage solution to biogas desulfurization problems.

　　1.4 脱硫技术发展方向我国沼气科研和应用虽然有了一定的基础，但是发展缓慢，无论是基础研究，还是具体工艺技术、装备化程度以及标准化、产业化，与发达国家相比都还有相当的差距。为了解决沼气脱硫问题，需大力开发和应用新技术新工艺，同时对某些方面具有优势的传统工艺进行加强改良。干法脱硫反应快、去除率高、投资少，目前的短板在于其再生环节，通过自控系统可实现连续定量投加空气再生，扬长避短，作为二级处理，充分发挥其精细脱硫的特点，也是一级脱硫系统故障时的应急保证。因此，在大体量市政污泥消化沼气脱硫处理中，以生物脱硫替代传统湿法脱硫，外加同步再生干法脱硫，做到新技术与改良传统技术的新老结合，充分发挥各自优点，成为一个可行的解决方案。

　　1.4 Development direction of desulfurization technology Although China has a certain foundation for biogas research and application, its development is slow. Whether it is basic research, specific process technology, equipment level, standardization, or industrialization, there is still a considerable gap compared to developed countries. In order to solve the problem of biogas desulfurization, it is necessary to vigorously develop and apply new technologies and processes, while strengthening and improving traditional processes that have advantages in certain aspects. Dry desulfurization has the advantages of fast reaction, high removal rate, and low investment. The current weakness lies in its regeneration process. Through the automatic control system, continuous and quantitative air regeneration can be achieved, highlighting its strengths and avoiding its weaknesses. As a secondary treatment, it fully utilizes its fine desulfurization characteristics and is also an emergency guarantee in case of a failure in the primary desulfurization system. Therefore, in the large-scale municipal sludge digestion and biogas desulfurization treatment, replacing traditional wet desulfurization with biological desulfurization and adding synchronous regeneration dry desulfurization can achieve a combination of new and improved traditional technologies, fully leveraging their respective advantages and becoming a feasible solution.

　　2、生物脱硫工艺在生物脱硫过程中，起主要作用的是脱硫细菌。按其性状大致可以分为2类，即：有色硫细菌和无色硫细菌。有色硫细菌因为含有光合色素而能够进行光合作用，主要为光能自养型脱硫菌。光能自养型微生物脱硫效率高，在脱除H2S的同时，还能脱除一定量的CO2，用于沼气脱硫很有优势，但是还没有工程应用方面的报道。原因是光能细菌在转化硫化物的过程中需要大量的辐射能，在经济和技术上都难以实现，同时生成单质硫颗粒后，反应器介质变得混浊，透光率大大降低，影响了脱硫效率。无色硫细菌体内不含光合色素，不能进行光合作用，主要为化能自养型脱硫菌，但也有异养脱硫菌的报道。化能自养型脱硫菌中的硫杆菌属是目前生物脱硫工艺中应用最广泛的一个菌属，代表性菌种包括氧化亚铁硫杆菌、氧化硫硫杆菌、排硫硫杆菌和脱氮硫杆菌等，其中脱氮硫杆菌因其具有较好的选择性和环境适应性，应用最多。化能型脱硫工艺目前开发得较为成熟，主要包括生物洗涤器、生物滤池和生物滴滤池3种。其中生物滤池主要用来处理气量大、浓度低的含硫臭气，对于沼气生物脱硫的应用则主要集中在生物滴滤池(见图1)和生物洗涤器反应器(见图2)上。生物滴滤池的系统造价和运行成本相对较低，但是为了避免单质硫堵塞填料，需要注入过量空气，将H2S氧化成硫酸根，同时空气中的惰性成分包括过量的氧都会进入沼气，降低其热值，且排放的废液中含有pH较低的稀硫酸，会对环境造成二次污染。考虑到净化沼气的再利用，碱再生生物洗涤沼气脱硫系统还能够实现单质硫回收的资源化利用。因此在消化沼气生物脱硫工艺选择时，优先推荐碱再生生物洗涤。不同沼气生物脱硫工艺比较见表1。

　　2. The desulfurization bacteria play a major role in the biological desulfurization process. According to their characteristics, they can be roughly divided into two categories: colored sulfur bacteria and colorless sulfur bacteria. Colored sulfur bacteria can carry out photosynthesis due to the presence of photosynthetic pigments, mainly being photoautotrophic desulfurization bacteria. Light autotrophic microorganisms have high desulfurization efficiency, and can remove a certain amount of CO2 while removing H2S, which is very advantageous for biogas desulfurization. However, there are no reports on engineering applications yet. The reason is that photobacteria require a large amount of radiation energy in the process of converting sulfides, which is difficult to achieve economically and technically. At the same time, after generating elemental sulfur particles, the reactor medium becomes turbid, and the light transmittance is greatly reduced, which affects the desulfurization efficiency. Colorless sulfur bacteria do not contain photosynthetic pigments in their bodies and cannot carry out photosynthesis. They are mainly chemoautotrophic desulfurization bacteria, but there are also reports of heterotrophic desulfurization bacteria. The genus Thiobacillus in chemoautotrophic desulfurization bacteria is currently the most widely used in biological desulfurization processes, with representative strains including Thiobacillus ferrooxidans, Thiobacillus thiooxidans, Thiobacillus thiooxidans, and Desulfobacterium denitrifying. Among them, Desulfobacterium denitrifying is the most widely used due to its good selectivity and environmental adaptability. The development of chemical energy desulfurization technology is currently relatively mature, mainly including three types: biological scrubbers, biological filters, and biological drip filters. The biological filter is mainly used to treat sulfur-containing odors with high gas volume and low concentration, while the application of biogas biological desulfurization is mainly focused on the biological drip filter (see Figure 1) and the biological scrubber reactor (see Figure 2). The system cost and operating cost of the biological drip filter are relatively low, but in order to avoid clogging of the packing with elemental sulfur, excessive air injection is required to oxidize H2S into sulfate ions. At the same time, inert components in the air, including excess oxygen, will enter the biogas, reducing its calorific value. The discharged waste liquid also contains dilute sulfuric acid with low pH, which will cause secondary pollution to the environment. Considering the reuse of purified biogas, the alkaline regeneration biological washing biogas desulfurization system can also achieve the resource utilization of elemental sulfur recovery. Therefore, when selecting the process of digesting biogas for biological desulfurization, alkaline regeneration biological washing is preferred. The comparison of different biogas biological desulfurization processes is shown in Table 1.

　　3、同步再生干法脱硫传统干法脱硫主要是利用水合氧化铁与沼气中的硫化氢反应，从而达到脱硫的目的。

　　3. Synchronous regeneration dry desulfurization. Traditional dry desulfurization mainly utilizes the reaction between hydrated iron oxide and hydrogen sulfide in biogas to achieve desulfurization.

　　这种干法脱硫会出现以下几个问题：①硫化铁塔内再生操作困难，脱硫剂难以被完全利用;②脱硫剂卸出塔体再生会占用较大的场地，且过程不易控制;③脱硫剂的装卸过程无法避免氧气进入塔体，可能造成塔内脱硫剂自燃;④塔内脱硫剂容易板结，甚至无法排出。同步再生脱硫是对传统干法脱硫的改进，在H2S脱除的同时，对脱硫剂进行连续再生，以充分利用脱硫剂的硫容。氧化铁脱硫及再生原理见式(1)、(2)，两者综合得到如式(3)所示的沼气脱硫反应式。由此可知，去除1mol的H2S理论上需要0.5mol的O2，但是实际工程中由于反应介质接触不够充分，再生空气投加的富余系数为1.2～1.8，空气量随H2S浓度及沼气流量变化的曲线如图3所示。可见，H2S含量越大，空气投加比例越高，但工程上一般控制空气投加比最大不超过4%。要实现脱硫剂的同步再生，关键要实现空气量根据H2S浓度和沼气流量进行自动投加，由于前者在一定时段内相对稳定，所以工程上根据沼气流量的动态变化，以预设比例投加空气，空压机变频可调，其控制原理见图4同步再生脱硫塔对脱硫剂的装卸采用了隔离仓的概念(见图5)，控制装卸过程可能进入塔体的空气量。隔离仓由上下两个阀门和一个缓冲仓构成。相关阀门需要通过消防耐火测试，并且取得认证。卸料时，先开启靠近塔体的卸料阀1，脱硫剂卸入缓存仓，然后关闭该阀。再开启卸料阀2，将仓中脱硫剂卸出，最后关闭卸料阀2。通过该方式，尽可能地避免空气带入塔体。该技术还采用独特的进气和加热措施(见图6)，防止塔体内部温度过低，出现水汽冷凝，造成脱硫剂板结。塔体外部配置加热装置，形式为伴热带或热水盘管，同时设有保温层，通过塔内温度反馈，自动调节热水量或伴热功率，以保证塔内温度比进气的露点温度高10~20℃。如图6所示，饱和沼气从塔中下部分进入塔体，沿着渐扩管向下，在渐扩管管口，气流折返向上经过脱硫剂层，之后从顶部流出塔体。进气在接触到脱硫剂之前经过预热，水汽凝出的可能性降低，同时经过二次分配，也增加了布气的均匀性。

　　This dry desulfurization method may encounter the following problems: ① difficult regeneration operation inside the sulfide iron tower, and difficulty in fully utilizing the desulfurizer; ② Unloading desulfurizer from the tower for regeneration will occupy a large area and the process is difficult to control; ③ The loading and unloading process of desulfurizer cannot avoid oxygen entering the tower body, which may cause spontaneous combustion of desulfurizer inside the tower; ④ The desulfurizer inside the tower is prone to caking and may even be unable to be discharged. Synchronous regeneration desulfurization is an improvement on traditional dry desulfurization, which continuously regenerates the desulfurizer while removing H2S, in order to fully utilize the sulfur capacity of the desulfurizer. The principle of iron oxide desulfurization and regeneration is shown in equations (1) and (2), and the two are combined to obtain the biogas desulfurization reaction equation shown in equation (3). From this, it can be seen that theoretically, removing 1mol of H2S requires 0.5mol of O2. However, in practical engineering, due to insufficient contact with the reaction medium, the excess coefficient of regenerated air is 1.2-1.8. The curve of air volume changing with H2S concentration and biogas flow rate is shown in Figure 3. It can be seen that the higher the H2S content, the higher the air addition ratio, but in engineering, the maximum air addition ratio is generally controlled to not exceed 4%. To achieve synchronous regeneration of desulfurizer, the key is to automatically add air based on H2S concentration and biogas flow rate. As the former is relatively stable for a certain period of time, air is added in a preset proportion according to the dynamic changes of biogas flow rate in the project. The frequency conversion of the air compressor is adjustable, and its control principle is shown in Figure 4. The synchronous regeneration desulfurization tower adopts the concept of an isolation compartment for the loading and unloading of desulfurizer (see Figure 5) to control the amount of air that may enter the tower during the loading and unloading process. The isolation chamber consists of two upper and lower valves and a buffer chamber. The relevant valves need to pass fire resistance testing and obtain certification. When unloading, first open the unloading valve 1 near the tower body, unload the desulfurizer into the buffer bin, and then close the valve. Open discharge valve 2 again to discharge the desulfurizer from the warehouse, and finally close discharge valve 2. Through this method, try to avoid air entering the tower as much as possible. This technology also adopts unique intake and heating measures (see Figure 6) to prevent the internal temperature of the tower from being too low, resulting in water vapor condensation and causing the desulfurizer to plate. A heating device is installed outside the tower, in the form of a heat tracing or hot water coil, with an insulation layer. Through temperature feedback inside the tower, the amount of hot water or heat tracing power is automatically adjusted to ensure that the temperature inside the tower is 10-20 ℃ higher than the dew point temperature of the inlet air. As shown in Figure 6, saturated biogas enters the tower body from the lower part of the tower, flows downwards along the expanding pipe, and at the mouth of the expanding pipe, the airflow returns upwards through the desulfurizer layer before flowing out of the tower body from the top. The intake is preheated before coming into contact with the desulfurizer, reducing the possibility of water vapor condensation. At the same time, it undergoes secondary distribution, which also increases the uniformity of gas distribution.

　　4、生物+同步再生干法脱硫工程应用案例4.1 脱硫系统主要工艺参数华东某大型市政污泥厌氧消化项目脱硫系统采用碱再生生物洗涤+同步再生干法脱硫工艺，主要工艺参数如表2所示。

　　4. Application case of biological+synchronous regeneration dry desulfurization project 4.1 Main process parameters of desulfurization system. The desulfurization system of a large municipal sludge anaerobic digestion project in East China adopts alkaline regeneration biological washing+synchronous regeneration dry desulfurization process. The main process parameters are shown in Table 2.

　　4.2 脱硫系统组成及主要设备参数4.2.1 生物脱硫部分生物脱硫单元采用碱再生生物洗涤工艺，共分A、B两条线，主要设备包括生物洗涤塔、生物反应器和硫沉淀器等，总装机功率148kW，实际运行功率107kW。①生物洗涤塔含H2S沼气进入生物洗涤塔，与洗涤液在塔内逆流接触，H2S被洗涤液吸收。洗涤塔内装有填料，目的是增加气液接触的面积。洗涤液由循环泵从生物反应器的脱气区泵入洗涤塔，洗涤水在塔底收集后流向生物反应器。脱硫后的气体从洗涤塔顶部排出。洗涤塔共4台，单台过气量1000m?/h，尺寸D1.2m×H15.8m，HDPE材质，填料高度6m，顶部设有除沫器，用来去除沼气出气中夹带的液滴;循环泵4用2备，离心泵，流量84m?/h，扬程210kPa，电机功率11kW。②生物反应器含有硫化物的洗涤液重力流入生物反应器。生物反应器液相中含有硫杆菌，通过控制DO水平将硫化物生物氧化，使之主要生成单质硫，同时再生形成吸收H2S所需的碱。反应器中无固定微生物的载体，生物硫本身充当了载体的角色。生物反应器2台，单台尺寸D2.9m×H6.0m，HDPE材质;配套曝气鼓风机4用2备，180m?/h，60kPa，5.5kW，变频控制;营养盐投加泵2台，电磁驱动隔膜计量泵，1.6L/h，0.76MPa，0.012kW，手动冲程调节;NaOH投加泵2用1备，电磁隔膜计量泵，90L/h，0.7MPa，0.25kW，手动冲程调节;测量循环泵2台，25m?/h，150kPa，2.2kW。③硫沉淀器反应液由生物反应器连续泵向硫沉淀器，在此产物硫与洗涤液分离，沉淀器的上清液回流到生物反应器，单质硫泵入硫贮槽。硫贮槽的硫污泥经搅拌器混匀后泵入储泥罐，并定期外运。硫沉淀器2台，单台尺寸D1.0m×H6.0m，HDPE材质;硫贮槽1台，尺寸D2.0m×H3.5m，HDPE材质;硫污泥泵1台，用于将硫污泥自沉淀器泵送至硫贮槽，软管泵，200L/h，0.5MPa，0.75kW;硫外送泵1台，软管泵，500L/h，0.5MPa，0.75kW。④辅助单元为维持生物反应最适宜的温度，配套循环冷却单元1套，包括板式换热器2台，45kW;冷却水泵1用1备，立式离心泵，20m?/h，330kPa，5.5kW。4.2.2 同步再生干法脱硫部分沼气经过生物脱硫后，H2S含量大幅降低，然后进入干法脱硫单元精脱硫，使H2S含量进一步下降，确保满足设计要求。H2S的脱除与脱硫剂的氧化再生在脱硫塔中同时进行，大大提高了传统干法脱硫再生环节的效率。沼气系统正常运行时，生物脱硫出口H2S浓度在100mg/m?以下，同步再生脱硫塔可将之进一步处理到1mg/m?以下。如遇到生物脱硫故障，仅依靠碱洗脱硫，在干式脱硫塔进口H2S浓度可能增加至300～500mg/m?甚至更高时，同步再生干法脱硫塔亦可保证出口H2S含量小于20mg/m?，只是脱硫剂的消耗量会相应增加。但作为沼气脱硫系统故障时的短期应用，事实上也起到了应急保障的作用。脱硫塔共计2台，单台最大过气量2000m?/h，停留时间1.8min，空塔滤速0.1m/s。脱硫塔尺寸D2.8m×H14.2m，单台有效容积60m?，316L不锈钢材质，热水盘管加热方式，外壳配岩棉保温层;气环式压缩机2台，20m?/h，变频可调;伴热泵2台，立式离心泵，2m?/h，100kPa，0.37kW;氧化铁脱硫剂，硫容40%，约0.7t/m?，孔隙率50%，直径1cm，长2~3cm，强度50N/cm，总装填量约84t。

　　4.2 Composition and main equipment parameters of desulfurization system 4.2.1 Biological desulfurization section The biological desulfurization unit adopts alkaline regeneration biological washing process, which is divided into two lines A and B. The main equipment includes biological washing tower, bioreactor, and sulfur precipitant, with a total installed power of 148kW and an actual operating power of 107kW. ① The biogas containing H2S enters the biological washing tower and comes into contact with the washing solution in reverse flow inside the tower, and H2S is absorbed by the washing solution. The washing tower is equipped with packing to increase the area of gas-liquid contact. The washing solution is pumped from the deaeration zone of the bioreactor into the washing tower by a circulation pump, and the washing water is collected at the bottom of the tower and flows towards the bioreactor. The desulfurized gas is discharged from the top of the scrubbing tower. There are a total of 4 washing towers, each with a gas flow rate of 1000m ?/h, dimensions of D1.2m × H15.8m, made of HDPE material, and a packing height of 6m. The top is equipped with a demister to remove liquid droplets carried in the biogas exhaust; Circulating pump 4 in use and 2 as backup, centrifugal pump, flow rate 84m?/h, head 210kPa, motor power 11kW. ② The washing solution containing sulfides flows into the bioreactor by gravity. The liquid phase of the bioreactor contains sulfur bacteria. By controlling the DO level, sulfides are biologically oxidized to mainly produce elemental sulfur, while regenerating to form the alkali required for H2S absorption. There is no fixed microbial carrier in the reactor, and biological sulfur itself acts as a carrier. Two bioreactors, each measuring D2.9m × H6.0m and made of HDPE material; Equipped with 4 aeration blowers for use and 2 backup, 180m ?/h, 60kPa, 5.5kW, frequency conversion control; 2 nutrient dosing pumps, electromagnetic driven diaphragm metering pump, 1.6L/h, 0.76MPa, 0.012kW, manual stroke adjustment; NaOH dosing pump 2 in use and 1 backup, electromagnetic diaphragm metering pump, 90L/h, 0.7MPa, 0.25kW, manual stroke adjustment; Measure 2 circulating pumps, 25m?/h, 150kPa, 2.2kW. ③ The reaction solution of the sulfur precipitator is continuously pumped from the bioreactor to the sulfur precipitator, where the product sulfur is separated from the washing solution. The supernatant of the precipitator flows back to the bioreactor, and elemental sulfur is pumped into the sulfur storage tank. The sulfur sludge in the sulfur storage tank is mixed by a mixer and pumped into the storage tank, and is regularly transported outside. Two sulfur precipitators, each measuring D1.0m × H6.0m, made of HDPE material; One sulfur storage tank, size D2.0m × H3.5m, made of HDPE material; One sulfur sludge pump, used to pump sulfur sludge from the sedimentation tank to the sulfur storage tank, hose pump, 200L/h, 0.5MPa, 0.75kW; One sulfur export pump, hose pump, 500L/h, 0.5MPa, 0.75kW. ④ To maintain the most suitable temperature for biological reactions, the auxiliary unit is equipped with one set of circulating cooling unit, including two plate heat exchangers with a power of 45kW; one cooling water pump is in use and one backup, a vertical centrifugal pump with a capacity of 20m ?/h, 330kPa, and 5.5kW. 4.2.2 Synchronous regeneration of dry flue gas. After biological desulfurization, the H2S content is significantly reduced, and then it enters the dry flue gas desulfurization unit for fine desulfurization, further reducing the H2S content to ensure compliance with design requirements. The removal of H2S and the oxidation regeneration of desulfurizer are carried out simultaneously in the desulfurization tower, greatly improving the efficiency of the traditional dry desulfurization regeneration process. When the biogas system is operating normally, is the H2S concentration at the outlet of the biological desulfurization system 100mg/m? Can the synchronous regeneration desulfurization tower further process it to 1mg/m? following. If encountering a biological desulfurization failure, relying solely on alkaline washing desulfurization may increase the H2S concentration at the inlet of the dry desulfurization tower to 300-500mg/m? Even higher, can the synchronous regeneration dry desulfurization tower ensure that the H2S content at the outlet is less than 20mg/m? However, the consumption of desulfurizer will increase accordingly. But as a short-term application in the event of a malfunction in the biogas desulfurization system, it actually plays a role in emergency support. There are a total of 2 desulfurization towers, with a maximum gas flow rate of 2000m?/h per unit, a residence time of 1.8min, and an empty tower filtration rate of 0.1m/s. The size of the desulfurization tower is D2.8m × H14.2m, with an effective capacity of 60m ? per unit. It is made of 316L stainless steel and heated by a hot water coil. The outer shell is equipped with a rock wool insulation layer; Two gas ring compressors, 20m ?/h, with adjustable frequency conversion; Two companion heat pumps, vertical centrifugal pumps, 2m ?/h, 100kPa, 0.37kW; Iron oxide desulfurizer with a sulfur capacity of 40%, approximately 0.7t/m? The porosity is 50%, the diameter is 1cm, the length is 2-3cm, the strength is 50N/cm, and the total filling amount is about 84t.

　　4.3 运行结果经过调试、试运行，装置达到稳定运行状态，为检验脱硫系统的综合处理能力，进行了性能测试。检测表明，沼气的平均处理量达到了48166m?/d(见图7)，较设计值(44512m?/d)略高。沼气的进气H2S浓度为4125～7425mg/m?，波动范围较大，但碱再生生物脱硫系统表现出优异的耐冲击及H2S高效去除能力，A、B两套装置出气H2S均小于27mg/m?，平均11.72mg/m?，去除效率均大于99%。生物脱硫虽然没有全部直接达到设计要求的20mg/m?，但经过同步再生干法脱硫后，所有出气均未检出H2S(见图8)，证明本项目生物+同步再生干法脱硫工艺是一个成功的选择。另外，碱再生生物洗涤脱硫单元的碱耗平均为0.63kgNaOH/kgH2S(见图9)，远远低于传统碱吸收湿法脱硫的碱耗(3～5kgNaOH/kgH2S)，也证明了系统通过自身运行实现了碱再生的目的，药耗减少，运行成本降低。从以上运行效果看，生物脱硫系统能够满足实际要求，干式脱硫系统起到了双保险作用。以生物脱硫出气H2S平均浓度为11.72mg/m?计，日脱硫剂消耗量约为1~2kg/d，脱硫剂更换时间长达若干年。如果生物脱硫出现故障或效能下降，脱硫塔在保证处理效果的前提下，脱硫剂更换时间将大幅缩短。以上述沼气进气平均流量为48166m?/d、H2S浓度区间上限为7500mg/m?计，在不同生物脱硫效果下脱硫剂消耗情况见图10。由图10可见，在生物脱硫对H2S的去除率仅有60%时，每日脱硫剂耗量达到近600kg/d，脱硫剂更换时间长达140d以上，因此在生物脱硫短时故障、脱硫效果有所降低的情况下，同步再生干式脱硫塔仍能保证沼气系统稳定运行。

　　4.3 After debugging and trial operation, the device reached a stable operating state. To test the comprehensive processing capability of the desulfurization system, performance tests were conducted. Tests have shown that the average processing capacity of biogas has reached 48166m?/d (see Figure 7), slightly higher than the design value (44512m?/d). The H2S concentration in the intake of biogas is 4125-7425mg/m? The fluctuation range is relatively large, but the alkaline regeneration biological desulfurization system exhibits excellent shock resistance and efficient H2S removal ability. Both sets of devices A and B have H2S emissions of less than 27mg/m? On average, 11.72mg/m? The removal efficiency is all greater than 99%. Although not all biological desulfurization directly meets the design requirement of 20mg/m? However, after synchronous regeneration dry desulfurization, no H2S was detected in all the exhaust gases (see Figure 8), proving that the biological+synchronous regeneration dry desulfurization process in this project is a successful choice. In addition, the average alkali consumption of the alkaline regeneration biological washing desulfurization unit is 0.63kgNaOH/kgH2S (see Figure 9), which is much lower than the alkali consumption of traditional alkaline absorption wet desulfurization (3-5kgNaOH/kgH2S). This also proves that the system achieves the purpose of alkaline regeneration through its own operation, reduces drug consumption, and lowers operating costs. From the above operational effects, it can be seen that the biological desulfurization system can meet practical requirements, and the dry desulfurization system plays a dual insurance role. The average concentration of H2S in the gas produced by biological desulfurization is 11.72mg/m? The daily consumption of desulfurizer is about 1-2kg/d, and the replacement time of desulfurizer can last for several years. If there is a malfunction or a decrease in the efficiency of biological desulfurization, the replacement time of desulfurizer in the desulfurization tower will be significantly shortened while ensuring the treatment effect. Based on the above average flow rate of 48166m?/d for biogas intake and an upper limit of 7500mg/m for H2S concentration range? The consumption of desulfurizer under different biological desulfurization effects is shown in Figure 10. As shown in Figure 10, when the removal rate of H2S by biological desulfurization is only 60%, the daily consumption of desulfurizer reaches nearly 600kg/d, and the replacement time of desulfurizer is over 140d. Therefore, even in the case of short-term failure and reduced desulfurization effect of biological desulfurization, the synchronous regeneration dry desulfurization tower can still ensure the stable operation of the biogas system.

　　4.4 经济效益评价案例项目脱硫系统设备总投资约700万元，占地面积600m?，经性能测试核算处理成本约为0.101元/m?沼气，分别由电费、水费、NaOH药剂费、营养盐费、干式脱硫剂费、人工费、设备折旧费、运行维护费和其他费用等组成，各部分比例如图11所示。如果只计前五项直接运行成本，则折合0.039元/m?沼气，显著低于传统湿法脱硫，且用电成本占比最大，电耗约为0.029kW·h/m?沼气。

　　4.4 Economic Benefit Evaluation Case: The total investment of the desulfurization system equipment in the project is about 7 million yuan, covering an area of 600m ?. After performance testing, the processing cost is calculated to be about 0.101 yuan/m ? for biogas, which is composed of electricity, water, NaOH reagent, nutrient salt, dry desulfurizer, labor, equipment depreciation, operation and maintenance, and other expenses. The proportion of each part is shown in Figure 11. If only the first five direct operating costs are included, it is equivalent to 0.039 yuan/m ? of biogas, which is significantly lower than traditional wet desulfurization, and the proportion of electricity cost is the largest, with an electricity consumption of about 0.029 kW · h/m ?? Biogas.

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