化学吸收工艺，是一种成熟的从混合气体中脱除二氧化碳的净化技术，因其对沼气中CH4和CO2气体具有高度的选择性吸收的特性，而成为沼气提纯为生物天然气领域里CH4回收率，产品气中CH4含量的脱碳方法。

Chemical absorption process is a mature purification technology that efficiently removes carbon dioxide from mixed gases. Due to its highly selective absorption of CH4 and CO2 gases in biogas, it has become the decarbonization method with the highest CH4 recovery rate and highest CH4 content in product gas in the field of biogas purification.

化学吸收法的原理是在催化剂条件下，采用吸收溶液，利用酸碱中和反应，吸收沼气中的二氧化碳、硫化氢等酸性物质，同时也能吸收氨等易溶于水的气体。吸收了各种杂质的气体通过溶液自净系统和气体再生系统释放出各种杂质和气体，溶液得到循环使用。

The principle of chemical absorption method is to use an absorption solution under catalyst conditions, utilize acid-base neutralization reaction, absorb acidic substances such as carbon dioxide and hydrogen sulfide in biogas, and also absorb gases that are easily soluble in water such as ammonia. The gas that has absorbed various impurities is released through the solution self purification system and gas regeneration system, and the solution is recycled.

常用的吸收溶液有乙醇胺(MEA)、二乙醇胺(DEA)、甲基二乙醇胺(MDEA)。由于CO2被吸收后与胺溶液发生了化学反应，因此吸收过程可以在较低的压力条件下进行，一般情况下只需要在沼气已有压力的基础上稍微提高一些压力即可。胺溶液的再生过程比较困难，需要160℃的温度条件，因此，运行过程需要消耗大量的工艺用热，存在运行能耗高的弊端。此外，由于存在蒸发损失，运行过程需要经常补充胺溶液。如果沼气含有高浓度的H2S，需要提前进行脱硫处理，否则会导致化学吸收剂中毒。

The commonly used absorption solutions include ethanolamine (MEA), diethanolamine (DEA), and methyldiethanolamine (MDEA). Due to the chemical reaction between CO2 and amine solution after absorption, the absorption process can be carried out under lower pressure conditions. Generally, only a slight increase in pressure is needed on the basis of the existing pressure of biogas. The regeneration process of amine solution is relatively difficult, requiring a temperature condition of 160 ℃. Therefore, the operation process requires a large amount of process heat consumption, which has the disadvantage of high energy consumption during operation. In addition, due to the existence of evaporation loss, the operation process requires frequent supplementation of amine solution. If biogas contains high concentrations of H2S, desulfurization treatment needs to be carried out in advance, otherwise it may lead to chemical absorbent poisoning.

工程中沼气脱硫后，通过沼气泵通入装有填料的吸收塔中，同时脱除二氧化碳、硫化氢，然后将产品气冷凝脱水后，在后续系统中进行压缩储存利用。吸收溶液通过再生塔再生，返回吸收塔中，循环利用。

After the desulfurization of biogas in the project, it is pumped into the absorption tower equipped with fillers through a biogas pump, while removing carbon dioxide and hydrogen sulfide. Then, the product gas is condensed and dehydrated, and compressed, stored and utilized in the subsequent system. The absorption solution is regenerated through a regeneration tower and returned to the absorption tower for recycling.

化学吸收法的特点：

The characteristics of chemical absorption method:

工艺流程简单；

The process flow is simple;

投资及运行费用低；

Low investment and operating costs;

能耗低、脱除效率高；

Low energy consumption and high removal efficiency;

吸收液再生较为困难。

The regeneration of absorption solution is relatively difficult.