生物脱硫技术是利用碱液吸收酸性气中的硫化氢，然后在硫黄杆菌的生化作用下产生硫黄，再经脱水、熔硫等操作，实现酸性气净化和硫黄回收的目的。介绍了生物脱硫技术的原理、工艺流程、操作要点及控制指标、主要设备、运行效果。实际运行结果表明，生物脱硫技术脱硫效率高、运行稳定，处理后的排放废气完全满足相关国家标准的要求

Biological desulfurization technology utilizes alkaline solution to absorb hydrogen sulfide from acidic gas, and then generates sulfur under the biochemical action of Thiobacillus. After dehydration, sulfur melting, and other operations, it achieves the purpose of acid gas purification and sulfur recovery. Introduced the principle, process flow, operating points, control indicators, main equipment, and operating effects of biological desulfurization technology. The actual operation results show that the biological desulfurization technology has high desulfurization efficiency and stable operation, and the treated exhaust gas fully meets the requirements of relevant national standards

1酸性气的产生及来源

1. The generation and source of acidic gas

煤中的硫在水煤浆气化炉内高温燃烧形成H2S，并随粗煤气进入低温甲醇洗单元。因H2S与甲醇同为极性分子，易形成氢键，因此H2S在甲醇中有很好的溶解度。粗煤气经甲醇洗涤塔内的甲醇洗涤后，CO2、H2S等气体均溶解在甲醇中。洗涤后的甲醇经减压闪蒸、低压解析、N2气提除去甲醇中大部分的CO2后，富含H2S的甲醇经热再生塔加热气提再生，甲醇与H2S之间的氢键断裂。从热再生塔顶部出来的富含H2S的酸性气体流量约1870m3/h(标态)，其中H2S为25.38%(体积分数，下同)、COS为0.02%、CO2为72.35%，经冷却分离后送至硫回收装置。

The sulfur in coal is burned at high temperature in the coal water slurry gasifier to form H2S, which enters the low-temperature methanol washing unit with the crude gas. Due to the fact that H2S and methanol are both polar molecules and are prone to forming hydrogen bonds, H2S has good solubility in methanol. After being washed with methanol in the methanol washing tower, the crude gas dissolves in methanol, including CO2 and H2S. After washing, methanol is subjected to vacuum flash distillation, low-pressure desorption, and N2 gas extraction to remove most of the CO2 in methanol. The methanol rich in H2S is heated and gas extracted in a hot regeneration tower for regeneration, and the hydrogen bond between methanol and H2S is broken. The flow rate of acidic gas rich in H2S coming out from the top of the hot regeneration tower is about 1870m3/h (standard state), of which H2S is 25.38% (volume fraction, the same below), COS is 0.02%, and CO2 is 72.35%. After cooling and separation, it is sent to the sulfur recovery unit.

2生物脱硫的原理

2. Principles of Biological Desulfurization

生物脱硫技术主要是采用硫黄杆菌来处理酸性气中的H2S，而硫黄杆菌是在自然界中产生，通过遗传培育或改良而来。硫黄杆菌的繁殖生长很快，4h就可以翻倍且成对数增长，而且对工艺条件、生产环境等都有很强的适应性，其生长过程中所需的能量主要来源于硫化物的氧化过程，碳源则来自于酸性气中的CO2。

Biological desulfurization technology mainly uses Thiobacillus to treat H2S in acidic gas, and Thiobacillus is produced in nature through genetic cultivation or improvement. Thiobacillus proliferates and grows rapidly, doubling and growing logarithmically within 4 hours, and has strong adaptability to process conditions and production environments. The energy required for its growth mainly comes from the oxidation process of sulfides, while the carbon source comes from CO2 in acidic gases.

来自低温甲醇洗单元的酸性气进入H2S吸收塔内与碱性溶液逆向接触，酸性气中的H2S和CO2被碱液吸收分别生成HS-、CO32-、HCO3-(H2S+OH-=HS-+H2O，H2S+CO32-=HS-+HCO3-，CO2+OH-=HCO3-，HCO3-+OH-=CO32-+H2O)。

The acidic gas from the low-temperature methanol washing unit enters the H2S absorption tower and comes into reverse contact with the alkaline solution. The H2S and CO2 in the acidic gas are absorbed by the alkaline solution to generate HS -, CO32-, and HCO3- (H2S+OH -=HS -+H2O, H2S+CO32-=HS -+HCO3-, CO2+OH -=HCO3-, HCO3-+OH -=CO32-+H2O), respectively.

吸收了酸性气中H2S和CO2的溶液进入生物反应器底部与空气混合，溶液中的HS-与O2反应生成硫和OH-(2HS-+O2=2S+2OH-，8SxHS-+4O2=S8+8Sx+8OH-)，溶液中的CO32-、HCO3-分解释放出OH-和CO2(CO32-+H2O=HCO3-+OH-；HCO3-=CO2+OH-)，碱液得到再生后循环使用。生物反应器内若O2过量，会发生副反应生成硫酸盐和硫代硫酸盐(HS-+2O2=SO42-+H+，2HS-+2O2= S2O32-+H2O)。在高浓度硫化物的作用下，生物菌的活性会降低，产生的硫酸盐和硫代硫酸盐增多。为减少副反应的发生，须合理控制生物反应器内空气的通入量，防止O2过剩。同时将硫黄脱水机分离出来的液体排至污水处理装置，并向生物反应器内补充新鲜水和碱液维持系统平衡。

The solution that absorbs H2S and CO2 from acidic gas enters the bottom of the bioreactor and mixes with air. The HS - in the solution reacts with O2 to generate sulfur and OH - (2HS -+O2=2S+2OH -, 8SxHS -+4O2=S8+8Sx+8OH -). The CO32- and HCO3- in the solution decompose to release OH - and CO2 (CO32-+H2O=HCO3-+OH -; HCO3-=CO2+OH -), and the alkaline solution is regenerated and reused. If there is excessive O2 in the bioreactor, side reactions will occur to generate sulfates and thiosulfates (HS -+2O2=SO42-+H+, 2HS -+2O2=S2O32-+H2O). Under the action of high concentrations of sulfides, the activity of biological bacteria will decrease, and the production of sulfates and thiosulfates will increase. To reduce the occurrence of side reactions, it is necessary to reasonably control the air intake in the bioreactor to prevent excess O2. At the same time, the liquid separated by the sulfur dehydrator is discharged to the sewage treatment device, and fresh water and alkaline solution are added to the bioreactor to maintain system balance.

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