Common process of biogas desulfurization and dehydration system

　　随着节能减排政策不断深入人心，很多企业都打算利用污水站的沼气部分代替天然气，进入锅炉燃烧或发电。那么，沼气利用前的硫化氢脱除工艺(脱硫)，就成为工厂和站长们的选择难点。当前，比较常用的工艺有干法脱硫、湿法脱硫和生物脱硫，本文就将三种工艺为您做一个简单的说明和对比。

　　With the policy of energy conservation and emission reduction becoming more and more popular, many enterprises intend to use the biogas part of the sewage station to replace the natural gas and enter the boiler for combustion or power generation. Then, the hydrogen sulfide removal process (desulfurization) before biogas utilization becomes the selection difficulty of the plant and station owners. At present, the more commonly used processes are dry desulfurization, wet desulfurization and biological desulfurization. This paper will make a simple description and comparison of the three processes for you.

　　一、常见的脱硫工艺

　　1、 Common desulfurization process

　　1. 干法脱硫

　　1. Dry desulfurization

　　干法、湿法和生物脱硫三大工艺比较

　　Comparison of dry, wet and bio desulfurization processes

　　沼气从脱硫塔的一端，经过填料层(主要成分是活性炭和氧化铁)净化后，从另一端流出。硫化氢与填料层的氧化铁发生反应，生成硫化铁;待氧化铁反应结束后，可进行再生。

　　Biogas flows from one end of the desulfurization tower to the other end after being purified by a packing layer (mainly composed of activated carbon and iron oxide). Hydrogen sulfide reacts with iron oxide in the filler layer to form iron sulfide, which can be regenerated after the reaction.

　　脱硫原理：

　　Desulfurization principle:

　　Fe2O3 ˙ H2O+ 3H2S = Fe2S3 + 4 H2O

　　Fe2O3 ˙ H2O+ 3H2S = Fe2S3 + 4 H2O

　　再生原理：

　　Regeneration principle:

　　Fe2S3 + 3/2 O2+ 3 H2O = Fe2O3 ˙H2O + 2 H2O+ 3 S

　　Fe2S3 + 3/2 O2+ 3 H2O = Fe2O3 ˙H2O + 2 H2O+ 3 S

　　2. 湿法脱硫

　　2. Wet desulfurization

　　湿法脱硫是将沼气送入洗涤塔，经碱性溶液洗涤吸收后流出，洗涤液进入富液槽、再生槽，通过使用化学药剂方法催化、氧化，zui终将硫化物转化为单质硫(硫泡沫)，吸收液可以再生循环使用。

　　Wet FGD is to send biogas into the washing tower, wash it through alkaline solution, wash it out, wash the liquid into the rich liquid tank and regeneration tank, and catalyze and oxidize it through chemical methods. Zui will eventually convert sulphide into elemental sulfur (sulfur foam), and the absorption liquid can be recycled and recycled.
                 

　　3. 生物脱硫

　　3. Biological desulfurization

　　生物脱硫也是湿法脱硫的一种，与上述湿法脱硫的催化氧化工艺相比，zui大区别是使用硫杆菌替代化学催化剂，将硫化物直接氧化成硫单质。

　　Biological desulfurization is also a kind of wet desulfurization. Compared with the above-mentioned catalytic oxidation process of wet desulfurization, Zui is different in that Thiobacillus is used instead of chemical catalyst to oxidize sulfide directly to sulfur substance.

　　反应原理：

　　Reaction principle:

　　H2S + OH-= HS- + H2O

　　H2S + OH-= HS- + H2O

　　HS- + 1/2O2= So + OH-

　　HS- + 1/2O2= So + OH-

　　说明：

　　explain:

　　1) 干法脱硫多用于硫化氢处理负荷小，或者对脱硫效果要求很高的工况。这时，干法脱硫多用于湿法脱硫或者生物脱硫之后，进一步脱硫。

　　1) Dry desulfurization is often used in the condition of small load or high demand for desulfurization effect. At this time, dry desulfurization is mostly used for further desulfurization after wet desulfurization or biological desulfurization.

　　2)在制定脱硫效果时，建议根据后续设备(锅炉或发电机)对硫化氢浓度的限制，以及沼气与天然气消耗量的比例，制定一个合理的脱除效果。我们通常建议zui终的硫化氢含量控制在25~100ppm。

　　2) When formulating the desulfurization effect, it is suggested to formulate a reasonable desulfurization effect according to the restriction of subsequent equipment (boiler or generator) on the concentration of hydrogen sulfide and the proportion of biogas and natural gas consumption. We usually suggest that the content of hydrogen sulfide in Zui should be controlled at 25-100ppm.

　　沼气脱水的方法

　　Method of methane dehydration

　　从发酵装置出来的沼气含有饱和水蒸气，可用3种方法将其去除。

　　The biogas from the fermentation plant contains saturated water vapor, which can be removed by three methods.

　　(1)冷分离法。

　　(1) Cold separation method.

　　冷分离法是利用压力能变化引起温度变化，使水蒸气从气相中冷凝下来的方法。常用的有两种流程：A．节流膨胀冷脱水法。一般用于高压燃气，经过节流膨胀或低温分离，使部分水冷凝下来。B．加压后冷却法。如净化气在0.8MPa压力下的冷却脱水.

　　The cold separation method is a method which uses the pressure energy change to cause the temperature change and make the water vapor condense from the gas phase. There are two commonly used processes: A. throttling expansion cold dehydration. Generally used for high-pressure gas, after throttling expansion or low-temperature separation, part of the water is condensed. B. Cooling after pressurization. For example, the purified gas is cooled and dehydrated under the pressure of 0.8MPa

　　(2)溶剂吸收法。属于这类脱水溶剂的有氯化钙、氯化锂及甘醇类。

　　(2) Solvent absorption method. The dehydrating solvents are calcium chloride, lithium chloride and glycol.

　　(3)固体物理吸水法。吸附是在固体表面力作用下产生的，根据表面力的性质分为化学吸附脱水后不能再生)和物理吸附(脱水后可再生)

　　(3) Solid physical water absorption method. Adsorption is generated under the action of solid surface force. According to the nature of surface force, it can be divided into chemical adsorption, dehydration, non regeneration and physical adsorption (regeneration after dehydration)

　　yl6809永利脱水系统是沼气生产中必不可少的设备，脱硫脱水设备净化沼气中的有害气体，保证在这一过程中沼气有效安全的产出。

　　The desulfurization and dehydration system of biogas is an essential equipment in biogas production. The desulfurization and dehydration equipment can purify the harmful gas in biogas and ensure the effective and safe output of biogas in this process.