生物脫硫技術是利用堿液吸收酸性氣中的硫化氫，然后在硫黃桿菌的生化作用下產(chǎn)生硫黃，再經(jīng)脫水、熔硫等操作，實現(xiàn)酸性氣凈化和硫黃回收的目的。介紹了生物脫硫技術的原理、工藝流程、操作要點及控制指標、主要設備、運行效果。實際運行結(jié)果表明，生物脫硫技術脫硫效率高、運行穩(wěn)定，處理后的排放廢氣完全滿足相關國家標準的要求。

　　Biological desulfurization technology uses alkaline solution to absorb hydrogen sulfide in acidic gas, and then produces sulfur through the biochemical action of sulfur bacteria. After dehydration, sulfur melting and other operations, the goal of acid gas purification and sulfur recovery is achieved. This article introduces 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.

　　國內(nèi)某煤化工項目氣化裝置選用水煤漿氣化工藝，凈化采用耐硫變換、低溫甲醇洗、液氮洗工藝，凈化后的合成氣送至氨合成裝置。在生產(chǎn)過程中，低溫甲醇洗產(chǎn)生的酸性氣通過生物脫硫技術進行處理。與傳統(tǒng)的硫回收工藝相比，生物脫硫工藝酸性氣中硫化氫脫除率高，工藝流程簡單，建設費用、維護費用低，日常消耗少，操作彈性大，產(chǎn)生的硫黃親水性好，不易堵塞設備和管道，裝置運行可靠度高，無需增設尾氣處理裝置，而且酸性氣處理過程中無二次污染。

　　The gasification unit of a domestic coal chemical project adopts the coal water slurry gasification process, and the purification adopts sulfur resistant transformation, low-temperature methanol washing, and liquid nitrogen washing processes. The purified synthesis gas is sent to the ammonia synthesis unit. During the production process, the acidic gas generated by low-temperature methanol washing is treated through biological desulfurization technology. Compared with traditional sulfur recovery processes, the biological desulfurization process has a higher removal rate of hydrogen sulfide in acidic gas, a simpler process flow, lower construction and maintenance costs, less daily consumption, greater operational flexibility, good hydrophilicity of the generated sulfur, less likely to block equipment and pipelines, high reliability of device operation, no need to add tail gas treatment equipment, and no secondary pollution during the acidic gas treatment process.

　　1酸性氣的產(chǎn)生及來源

　　1. Generation and Source of Acidic Gas

　　煤中的硫在水煤漿氣化爐內(nèi)高溫燃燒形成H2S，并隨粗煤氣進入低溫甲醇洗單元。因H2S與甲醇同為極性分子，易形成氫鍵，因此H2S在甲醇中有很好的溶解度。粗煤氣經(jīng)甲醇洗滌塔內(nèi)的甲醇洗滌后，CO2、H2S等氣體均溶解在甲醇中。洗滌后的甲醇經(jīng)減壓閃蒸、低壓解析、N2氣提除去甲醇中大部分的CO2后，富含H2S的甲醇經(jīng)熱再生塔加熱氣提再生，甲醇與H2S之間的氫鍵斷裂。從熱再生塔頂部出來的富含H2S的酸性氣體流量約1870m3/h(標態(tài))，其中H2S為25.38%(體積分數(shù)，下同)、COS為0.02%、CO2為72.35%，經(jīng)冷卻分離后送至硫回收裝置。

　　The sulfur in coal burns 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 polar molecules, they are prone to form hydrogen bonds, thus H2S has good solubility in methanol. After the crude coal gas is washed with methanol in the methanol washing tower, gases such as CO2 and H2S are dissolved in methanol. After washing, the methanol is subjected to vacuum flash evaporation, low-pressure desorption, and N2 gas stripping to remove most of the CO2 in the methanol. The methanol rich in H2S is then heated and gas stripped in a thermal regeneration tower for regeneration, and the hydrogen bonds between methanol and H2S are broken. The flow rate of acidic gas rich in H2S 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生物脫硫的原理

　　The principle of biological desulfurization

　　生物脫硫技術主要是采用硫黃桿菌來處理酸性氣中的H2S，而硫黃桿菌是在自然界中產(chǎn)生，通過遺傳培育或改良而來。硫黃桿菌的繁殖生長很快，4h就可以翻倍且成對數(shù)增長，而且對工藝條件、生產(chǎn)環(huán)境等都有很強的適應性，其生長過程中所需的能量主要來源于硫化物的氧化過程，碳源則來自于酸性氣中的CO2。

　　Biological desulfurization technology mainly uses sulfur bacteria to treat H2S in acidic gas, which is produced in nature through genetic cultivation or improvement. The reproduction and growth of sulfur bacteria are very fast, doubling and growing logarithmically in 4 hours, and have strong adaptability to process conditions, production environments, etc. The energy required for their growth mainly comes from the oxidation process of sulfides, and the carbon source comes from CO2 in acidic gas.

　　來自低溫甲醇洗單元的酸性氣進入H2S吸收塔內(nèi)與堿性溶液逆向接觸，酸性氣中的H2S和CO2被堿液吸收分別生成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 produce HS -, CO32-, HCO3- (H2S+OH -=HS -+H2O, H2S+CO32-=HS-+HCO3-，CO2+OH-=HCO3-，HCO3-+OH-=CO32-+H2O)。

　　吸收了酸性氣中H2S和CO2的溶液進入生物反應器底部與空氣混合，溶液中的HS-與O2反應生成硫和OH-(2HS-+O2=2S+2OH-，8SxHS-+4O2=S8+8Sx+8OH-)，溶液中的CO32-、HCO3-分解釋放出OH-和CO2(CO32-+H2O=HCO3-+OH-；HCO3-=CO2+OH-)，堿液得到再生后循環(huán)使用。生物反應器內(nèi)若O2過量，會發(fā)生副反應生成硫酸鹽和硫代硫酸鹽(HS-+2O2=SO42-+H+，2HS-+2O2= S2O32-+H2O)。在高濃度硫化物的作用下，生物菌的活性會降低，產(chǎn)生的硫酸鹽和硫代硫酸鹽增多。為減少副反應的發(fā)生，須合理控制生物反應器內(nèi)空氣的通入量，防止O2過剩。同時將硫黃脫水機分離出來的液體排至污水處理裝置，并向生物反應器內(nèi)補充新鮮水和堿液維持系統(tǒng)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 -). The alkaline solution is regenerated and recycled for use. If there is an excess of O2 in the bioreactor, side reactions will occur to produce 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 amount of air introduced into the bioreactor to prevent excess O2. At the same time, the liquid separated from the sulfur dehydrator is discharged to the sewage treatment unit, and fresh water and alkali solution are added to the bioreactor to maintain system balance.

　　3生物脫硫工藝流程

　　3. Biological desulfurization process flow

　　生物脫硫工藝流程見圖 1。

　　The process flow of biological desulfurization is shown in Figure 1.

　　詳見文章全文：

　　Please refer to the full article for details:

　　生物脫硫技術在煤化工酸性氣脫硫中的應用

　　Application of biological desulfurization technology in acid gas desulfurization in coal chemical industry

　　4生物脫硫工藝的操作要點及

　　4. Key points of operation for biological desulfurization process and

　　控制指標

　　Control indicators

　　生物脫硫工藝的操作要點包括H2S吸收塔的氣液比、溶液的pH和溶液的緩沖能力、氧化還原電位和生物反應器空氣通入量、排放和電導率、系統(tǒng)中固體(單質(zhì)硫)的濃度、溫度。

　　The key operating points of the biological desulfurization process include the gas-liquid ratio of the H2S absorption tower, the pH and buffering capacity of the solution, the oxidation-reduction potential and air flow rate of the bioreactor, emissions and conductivity, the concentration of solid (elemental sulfur) in the system, and temperature.

　　詳見文章全文：

　　Please refer to the full article for details:

　　生物脫硫技術在煤化工酸性氣脫硫中的應用

　　Application of biological desulfurization technology in acid gas desulfurization in coal chemical industry

　　5主要設備工作原理及作用

　　5. Working principles and functions of main equipment

　　生物脫硫裝置的主要設備有H2S吸收塔、生物反應器、硫黃沉降槽、熔硫釜等。

　　The main equipment of the biological desulfurization device includes H2S absorption tower, bioreactor, sulfur settling tank, sulfur melting kettle, etc.

　　H2S吸收塔內(nèi)裝填鮑爾環(huán)和必要的內(nèi)件，以確保吸收液從塔頂部均勻地噴灑到填料塔內(nèi)，氣體在塔內(nèi)與吸收液逆向接觸，使酸性氣中的H2S和部分CO2從氣相轉(zhuǎn)移至液相。為了防止吸收液發(fā)泡，塔頂設有噴淋裝置。

　　The H2S absorption tower is filled with a Bauer ring and necessary internal components to ensure that the absorption liquid is evenly sprayed from the top of the tower into the packed tower. The gas in the tower comes into reverse contact with the absorption liquid, causing H2S and some CO2 in the acidic gas to transfer from the gas phase to the liquid phase. In order to prevent the absorption liquid from foaming, a spray device is installed at the top of the tower.

　　生物反應器是脫硫工藝最關鍵的設備。空氣從底部通入，使HS-轉(zhuǎn)化為硫。為了提高HS-轉(zhuǎn)化率，在生物反應器內(nèi)配置特殊的內(nèi)件，保證了系統(tǒng)的氣液完全混合。同時頂部安裝噴嘴，以防止生物反應器內(nèi)的溶液發(fā)泡。

　　Bioreactors are the most critical equipment in desulfurization processes. Air is introduced from the bottom to convert HS - into sulfur. In order to improve the HS conversion rate, special internal components are installed in the bioreactor to ensure complete gas-liquid mixing in the system. At the same time, a nozzle is installed at the top to prevent the solution inside the bioreactor from foaming.

　　硫黃沉降槽是底部為錐形的容器，內(nèi)部設有溢流堰，塔頂設有噴嘴等，使貧液與硫黃顆粒通過靜態(tài)沉降的方式予以分離。

　　The sulfur settling tank is a cone-shaped container with an overflow weir inside and a nozzle at the top of the tower, which separates the lean solution from sulfur particles through static settling.

　　熔硫釜內(nèi)溫度按上低下高的梯度分布，硫漿進入釜內(nèi)后被逐漸加熱，硫泡沫破裂，細小的硫顆粒聚集變大沉降至釜底高溫區(qū)熔融，硫水分離后的清液上浮從熔硫釜上端旁側(cè)連續(xù)排出。

　　The temperature in the sulfur melting kettle is distributed according to the gradient of upper, lower and higher. The sulfur slurry is gradually heated after entering the kettle. The sulfur foam breaks, and the small sulfur particles gather and settle to the high temperature area at the bottom of the kettle for melting. The clear liquid after sulfur water separation floats up and is discharged continuously from the side of the upper end of the sulfur melting kettle.

　　6生產(chǎn)中其他操作及注意事項

　　6 Other operations and precautions in production

　　(1) 經(jīng)常觀察H2S吸收塔和生物反應器內(nèi)溶液的顏色。在操作正常時，生物反應器內(nèi)的溶液外觀呈灰白－黃色，類似硫黃產(chǎn)品的顏色，此時表明系統(tǒng)具有高的生物活性和硫黃產(chǎn)量。當系統(tǒng)不正常時，生物菌的生物活性被抑制，硫化物在裝置內(nèi)累積并與元素硫反應生成多硫化物，氧化還原電位會降低，H2S吸收塔和生物反應器內(nèi)的液體將變成暗綠色。

　　(1) Regularly observe the color of the solution in the H2S absorption tower and bioreactor. When operating normally, the appearance of the solution in the bioreactor is gray white yellow, similar to the color of sulfur products, indicating that the system has high biological activity and sulfur production. When the system is abnormal, the biological activity of the bacteria is inhibited, and sulfides accumulate in the device and react with elemental sulfur to produce polysulfides. The oxidation-reduction potential will decrease, and the liquid in the H2S absorption tower and bioreactor will turn dark green.

　　(2) 生物菌的備份。當上游氣體成分嚴重偏離設計工況或本裝置操作維護不當?shù)瘸霈F(xiàn)極端情況時，可能會對生物脫硫系統(tǒng)造成不可逆的破壞。如出現(xiàn)氣體攜有過量的HCN、NH3、CH3OH，液相中重金屬超標，系統(tǒng)pH和溫度過低等問題，生物菌就有可能會被殺死。因此須對生物菌進行備份，以便裝置快速重啟。在正常運行時，一般每隔3個月對生物菌重新備份一次。進行生物菌備份時，首先根據(jù)溶液的顏色判斷是否適宜進行取樣，然后用4個200L的無毒塑料桶在硫漿泵出口取樣，再密閉置于常溫(25~40℃)貯藏室內(nèi)保存。

　　(2) Backup of biological bacteria. When the upstream gas composition deviates significantly from the design conditions or when there are extreme situations such as improper operation and maintenance of this device, it may cause irreversible damage to the biological desulfurization system. If there are problems such as excessive HCN, NH3, CH3OH in the gas, excessive heavy metals in the liquid phase, low system pH and temperature, etc., biological bacteria may be killed. Therefore, it is necessary to backup the biological bacteria in order to quickly restart the device. During normal operation, the biological bacteria are usually backed up again every 3 months. When backing up biological bacteria, first determine whether it is suitable to take samples based on the color of the solution, then use four 200L non-toxic plastic buckets to take samples at the outlet of the sulfur slurry pump, and then store them in a sealed room at room temperature (25-40 ℃).

　　(3) 系統(tǒng)通過生物菌來處理酸性氣中的H2S，生物菌活性數(shù)量將嚴重影響裝置負荷及生產(chǎn)情況。在前系統(tǒng)負荷波動較大時，酸性氣量突然減少或增多，會導致生物菌死亡或因生物菌數(shù)量與負荷不匹配造成系統(tǒng)紊亂，對裝置運行影響較大。當系統(tǒng)開車時，先培養(yǎng)裝置內(nèi)的生物菌菌落，根據(jù)系統(tǒng)生物菌狀況緩慢提高負荷，否則容易因生物菌數(shù)量較少、酸性氣量過大，導致排放氣中的H2S含量超標。因此，在前系統(tǒng)負荷波動或開停車時，應密切關注硫回收裝置的操作界面，嚴格控制H2S吸收塔的氣液比、pH、氧化還原電位和生物反應器通入的空氣量、排放量、電導率、溫度，若指標出現(xiàn)異常應及時處理，防止工況惡化。

　　(3) The system uses biological bacteria to treat H2S in acidic gas, and the activity of biological bacteria will seriously affect the load and production situation of the equipment. When there is a large fluctuation in the load of the front-end system, a sudden decrease or increase in the amount of acidic gas can lead to the death of biological bacteria or system disorder caused by the mismatch between the number of biological bacteria and the load, which has a significant impact on the operation of the device. When the system is running, first cultivate the bacterial colonies inside the device, and slowly increase the load according to the condition of the system's biological bacteria. Otherwise, it is easy for the H2S content in the exhaust gas to exceed the standard due to a small number of biological bacteria and excessive acidic gas. Therefore, when the load of the front-end system fluctuates or starts and stops, close attention should be paid to the operating interface of the sulfur recovery unit, and the gas-liquid ratio, pH, oxidation-reduction potential of the H2S absorption tower, as well as the air volume, emissions, conductivity, and temperature of the bioreactor should be strictly controlled. If there are any abnormalities in the indicators, they should be dealt with in a timely manner to prevent deterioration of the working conditions.

　　7運行效果分析

　　7. Analysis of Operational Effectiveness

　　生物脫硫裝置投產(chǎn)后，設備可靠度高，運行穩(wěn)定，硫黃產(chǎn)量可達13.5t/d，能夠滿足生產(chǎn)需求。

　　After the biological desulfurization device is put into operation, the equipment has high reliability and stable operation, and the sulfur production can reach 13.5t/d, which can meet the production demand.

　　8結(jié)語

　　8 Conclusion

　　與其他硫回收技術相比，生物脫硫技術具有投資費用低、工藝流程簡單、操作方便、運行成本低、設備和管道不易堵塞、對酸性氣要求低、適用范圍廣等特點，裝置運行穩(wěn)定可靠，無二次污染，脫硫效果良好。

　　Compared with other sulfur recovery technologies, biological desulfurization technology has the characteristics of low investment cost, simple process flow, convenient operation, low operating cost, less likely to block equipment and pipelines, low requirements for acidic gas, and wide applicability. The device operates stably and reliably, without secondary pollution, and has good desulfurization effect.

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