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湿式氧化法脱硫在沼气脱硫中的应用

时间:2020-06-19
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  在厌氧发酵沼气处理过程中,含硫化合物会被转化为H2S,沼气中H2S的含量在几百毫克到几十克/Nm3不等,对管道、金属设备、燃烧器以及仪器、仪表都有很强腐蚀性,因此,影响了沼气综合利用。我国环保标准规定,利用沼气能源时,沼气中H2S含量不得超过20mg/Nm3,不管是工业还是民用沼气,都需要除去,沼气脱硫作为沼气综合利用中更重要的一个环节越来越受到重视。今天综合沼气主要的脱硫方法简单介绍一下。
  In the process of anaerobic fermentation biogas treatment, sulfur compounds will be converted into H2S. The content of H2S in biogas varies from several hundred milligrams to dozens of grams / Nm3, which is very corrosive to pipelines, metal equipment, burners, instruments and meters. Therefore, it affects the comprehensive utilization of biogas. According to China's environmental protection standards, when biogas energy is used, the content of H2S in biogas shall not exceed 20mg / Nm3. No matter industrial or civil biogas, it needs to be removed. As the most important link in the comprehensive utilization of biogas, biogas desulfurization is paid more and more attention. Today, the main desulfurization methods of comprehensive biogas are briefly introduced.
  一、干法脱硫
  1、 Dry desulfurization
  干法脱除沼气中H2S的基本原理是把H2S氧化成硫或硫化物的一种方法,物理吸附的过程。干法脱硫设备的结构是,在一个塔器内放入填料,填料层装有活性碳,氧化铁等。沼气以低流速从一端进入塔器内的填料层,H2S氧化成硫或硫化物,余留在填料层中,净化后沼气从塔器另一端排出。其优点∶结构简单,使用方便,工作过程无需人员值守,适合低硫化氢,低气量,精脱硫过程。
  The basic principle of removing H2S from biogas by dry method is to oxidize H2S into sulfur or sulfide, which is a process of physical adsorption. The structure of dry desulfurization equipment is to put packing in a tower, and the packing layer is filled with activated carbon, iron oxide, etc. The biogas enters the packing layer in the tower at a low flow rate from one end, and the H2S is oxidized to sulfur or sulfide, which is left in the packing layer. After purification, the biogas is discharged from the other end of the tower. Its advantages: simple structure, easy to use, no need to watch the working process, suitable for low hydrogen sulfide, low gas content, fine desulfurization process.
  沼气提纯
  生物脱硫技术包括生物过滤法,生物吸附法等,其微生物种群随环境改变而改变。在生物脱硫过程中,氧化态的含硫污染物必须先经过生物还原作用生成H2S或硫化物,然后再经过生物氧化过程生成单质硫才能脱除。在大多数生物反应器中,微生物种类以细菌为主,真菌为次,极少有酵母菌。常用的细菌是硫杆菌,属氧化亚铁硫杆菌,脱氮硫杆菌及排硫杆菌。更成功的代表是氧化亚铁硫杆菌。
  Biological desulfurization technology includes biofiltration, biosorption and so on. Its microbial population changes with the change of environment. In the process of biological desulfurization, the oxidized sulfur-containing pollutants must first be reduced to H2S or sulfide by biological reduction, and then to elemental sulfur by biological oxidation. In most bioreactors, the main microbial species are bacteria, followed by fungi, and few yeast. The commonly used bacteria are Thiobacillus, Thiobacillus ferrooxidans, Thiobacillus denitrifier and Thiobacillus thiooxidans. The most successful representative is Thiobacillus ferrooxidans.
  生物脱硫优点是∶不需要催化剂和氧化剂(空气除外),不需要化学污泥,产生很少的生物污染,能耗低,回收硫效率高,过程控制要求比较高。
  The advantages of biological desulfurization are: no catalyst and oxidant (except air), no chemical sludge, little biological pollution, low energy consumption, high sulfur recovery efficiency, high process control requirements.
  三、湿法脱硫
  3、 Wet desulfurization
  目前国内大型沼气脱硫厂家较多采用沼气湿法脱硫技术,其典型代表工艺有∶沼气中H2S在含有河北品臣公司的PTS沼气专用脱硫剂的碱性溶液中氧化成单质硫的湿法脱硫技术,该技术流程较为简单,脱硫效率高。
  At present, the domestic large-scale biogas desulfurization manufacturers mostly adopt the wet desulfurization technology of biogas. The typical representative technology is: the wet desulfurization technology of oxidation of H2S in biogas into elemental sulfur in the alkaline solution containing PTS special desulfurization agent for Biogas of Hebei Pinchen company. The technical process is relatively simple and the desulfurization efficiency is high.
  1、基本原理:
  1. Basic principle:
  在PTS沼气专用催化剂参于下有吸收和再生两个过程,由于沼气中CO2较高,为保证碱性溶液的吸收效果,一般用纯碱作为碱源。其反应式为∶
  In order to ensure the absorption effect of alkaline solution, soda ash is generally used as the alkali source. The reaction formula is:
  H2S的化学吸收反应:
  Chemical absorption reaction of H2S:
  H2S+Na2CO3=NaHS+NaHCO3
  H2S+Na2CO3=NaHS+NaHCO3
  NaHS+(X-1)S+NaHCO3=Na2Sx+CO2+H2O
  NaHS+(X-1)S+NaHCO3=Na2Sx+CO2+H2O
  催化氧化析硫反应:
  Catalytic oxidation sulfur evolution reaction:
  2NaHS+O2 =2NaOH+2S(品臣PTS催化剂的作用下)
  2nahs + O2 = 2naoh + 2S (under the action of Pinchen PTS catalyst)
  2、主要流程
  2. Main process
  含硫沼气从脱硫塔底部进入,与碱性脱硫液逆流接触。硫化氢被溶液吸收,净化沼气从塔顶排出。吸收硫化氢的脱硫液为富液,经富液槽用富液泵加压送至再生槽与空气混合。其中硫以硫泡沫的形式浮选出来。再生后的脱硫贫液进入贫液槽,经泵循环进入脱硫塔使用。
  The sulfur-containing biogas enters from the bottom of the desulfurization tower and contacts with the alkaline desulfurization liquid in reverse flow. Hydrogen sulfide is absorbed by the solution and purified biogas is discharged from the top of the tower. The desulfurizing liquid absorbing hydrogen sulfide is rich liquid, which is pressurized by rich liquid pump through rich liquid tank and sent to regeneration tank for mixing with air. Sulfur is floatation in the form of sulfur foam. The regenerated desulfurized lean liquid enters into the lean liquid tank and circulates into the desulfurizing tower for use through the pump.
  3、主要工艺指标控制
  3. Main process index control
  总碱度18﹣25g/L
  Total alkalinity 18-25g / L
  溶液PH值8.2﹣8.5
  PH value of solution 8.2-8.5
  PTS沼气专用浓度20﹣35ppm
  Special concentration of PTS biogas 20-35ppm
  脱硫液温度35﹣40℃
  Desulfurization liquid temperature 35-40 ℃
  沼气脱硫技术发展相对较成熟,根据实际情况选择合适的产品。但每种方法都有自己的特点和适应条件。实现沼气循环综合利用,提高沼气脱硫效率,加强沼气工程新技术和新设备研发从而降低工程成本,一直是我们的努力方向。
  The development of biogas desulfurization technology is relatively mature, and appropriate products are selected according to the actual situation. But each method has its own characteristics and adaptive conditions. To realize the comprehensive utilization of biogas cycle, improve the efficiency of biogas desulfurization, strengthen the research and development of new technology and equipment of biogas engineering, so as to reduce the engineering cost, has always been our efforts.