化學(xué)吸收工藝，是一種成熟的從混合氣體中高效脫除二氧化碳的凈化技術(shù)，因其對沼氣中CH4和CO2氣體具有高度的選擇性吸收的特性，而成為沼氣提純?yōu)樯锾烊粴忸I(lǐng)域里CH4回收率最高，產(chǎn)品氣中CH4含量最高的脫碳方法。

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.

化學(xué)吸收法的原理是在催化劑條件下，采用吸收溶液，利用酸堿中和反應(yīng)，吸收沼氣中的二氧化碳、硫化氫等酸性物質(zhì)，同時也能吸收氨等易溶于水的氣體。吸收了各種雜質(zhì)的氣體通過溶液自凈系統(tǒng)和氣體再生系統(tǒng)釋放出各種雜質(zhì)和氣體，溶液得到循環(huán)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被吸收后與胺溶液發(fā)生了化學(xué)反應(yīng)，因此吸收過程可以在較低的壓力條件下進(jìn)行，一般情況下只需要在沼氣已有壓力的基礎(chǔ)上稍微提高一些壓力即可。胺溶液的再生過程比較困難，需要160℃的溫度條件，因此，運行過程需要消耗大量的工藝用熱，存在運行能耗高的弊端。此外，由于存在蒸發(fā)損失，運行過程需要經(jīng)常補充胺溶液。如果沼氣含有高濃度的H2S，需要提前進(jìn)行脫硫處理，否則會導(dǎo)致化學(xué)吸收劑中毒。

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.

工程中沼氣脫硫后，通過沼氣泵通入裝有填料的吸收塔中，同時脫除二氧化碳、硫化氫，然后將產(chǎn)品氣冷凝脫水后，在后續(xù)系統(tǒng)中進(jìn)行壓縮儲存利用。吸收溶液通過再生塔再生，返回至吸收塔中，循環(huán)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.

化學(xué)吸收法的特點：

The characteristics of chemical absorption method:

工藝流程簡單；

The process flow is simple;

投資及運行費用低；

Low investment and operating costs;

能耗低、脫除效率高；

Low energy consumption and high removal efficiency;

吸收液再生較為困難。

The regeneration of absorption solution is relatively difficult.