目前沼气脱碳的工艺方法有膜分离、变压吸附（PSA）、化学吸收以及低温冷凝提纯法。膜分离膜分离提纯法是利用不同气体组分在压力驱动下通过膜的渗透性作用的不同来实现的，通常情况下二氧化碳的渗透速度快，作为快气以透过气排出，甲烷的渗透速度慢，作为慢气以透余气形式获得提纯产品气。

　　At present, the process methods for decarbonization of biogas include membrane separation, pressure swing adsorption (PSA), chemical absorption, and low-temperature condensation purification. The membrane separation and purification method is achieved by utilizing the different permeability effects of different gas components through the membrane under pressure drive. Generally, carbon dioxide has a fast permeation rate and is discharged as permeate gas as a fast gas, while methane has a slow permeation rate and is obtained as purified product gas in the form of permeate gas as a slow gas.

　　在工程中，为了提高甲烷气的浓度，常采用多级膜分离工艺。

　　In engineering, multi-stage membrane separation technology is often used to increase the concentration of methane gas.

　　工艺优点：模块化安装，可安装于集装箱内，扩展与增容简易，系统占地面小；能耗主要为压缩机电耗，且无需外来补充水和溶液。

　　Process advantages: modular installation, can be installed inside containers, easy expansion and capacity expansion, and the system takes up less floor space; The energy consumption is mainly due to the power consumption of the compressor, and there is no need for external water and solution supplementation.

　　工艺缺点：目前规模化应用少，投资高，分离膜依赖进口，且对沼气预处理要求高。

　　Process disadvantages: Currently, there are few large-scale applications, high investment, dependence on imported separation membranes, and high requirements for biogas pretreatment.

　　变压吸附（PSA）变压吸附提纯法是利用吸附剂（如分子筛等）对二氧化碳的选择性吸附特点, 即在吸附剂上二氧化碳相对其他气态组分有较高的分离系数, 来达到对沼气中二氧化碳进行脱除的目的。

　　The pressure swing adsorption (PSA) purification method utilizes the selective adsorption characteristics of adsorbents (such as molecular sieves) for carbon dioxide, which means that carbon dioxide has a higher separation coefficient compared to other gaseous components on the adsorbent, in order to achieve the goal of removing carbon dioxide from biogas.

　　在吸附过程中，原料气在加压条件下其中的二氧化碳被吸附在吸附塔内，甲烷等其他弱吸附性气体作为净化气排出，当吸附饱和后将吸附柱减压甚至抽成真空使被吸附的二氧化碳释放出来。为了保证对气体的连续处理要求，变压吸附法至少需要两个吸附塔, 也可是三塔、四塔或更多。

　　During the adsorption process, carbon dioxide in the raw gas is adsorbed in the adsorption tower under pressurized conditions, while other weakly adsorbing gases such as methane are discharged as purified gas. When the adsorption is saturated, the adsorption column is depressurized or even evacuated to release the adsorbed carbon dioxide. In order to ensure the continuous processing requirements for gases, the pressure swing adsorption method requires at least two adsorption towers, but can also have three towers, four towers, or more.

　　工艺优点：目前新开发的主副塔结构式变压吸附脱碳装置，改变了传统变压吸附甲烷回收率低、净化度低等问题。整个装置操作简便，维修量少，同时克服了化学脱碳的起泡、易腐蚀、耗蒸汽等缺点。

　　Process advantages: The newly developed main and auxiliary tower structure pressure swing adsorption decarbonization unit has changed the problems of low methane recovery rate and low purification degree in traditional pressure swing adsorption. The entire device is easy to operate, requires minimal maintenance, and overcomes the disadvantages of chemical decarbonization such as foaming, corrosion, and steam consumption.

　　工艺缺点：在实际工程运行中，变压吸附中的分子筛易中毒、失去活性，分子筛在变压吸附中所占成本比例较高。化学吸收吸收提纯法是利用有机胺溶液（一级胺、二级胺、三级胺、空间位阻胺等）与二氧化碳的物理化学吸收特性来实现的，即在吸收塔内的加压、常温条件下与沼气中的二氧化碳发生吸收反应进行脱碳提纯甲烷，吸收富液在再生塔内的减压、加热条件下发生逆向解析反应，释放出高纯度的二氧化碳气体，同时富液得到再生具备重新吸收二氧化碳的能力，从而实现沼气在吸收塔内的连续脱碳提纯甲烷过程，并使得脱碳液进行连续的吸收、再生循环工作

　　Process disadvantages: In actual engineering operation, molecular sieves in pressure swing adsorption are prone to poisoning and loss of activity, and the cost proportion of molecular sieves in pressure swing adsorption is relatively high. The chemical absorption absorption purification method is achieved by utilizing the physical and chemical absorption characteristics of organic amine solutions (primary amines, secondary amines, tertiary amines, steric hindrance amines, etc.) and carbon dioxide, that is, absorbing and reacting with carbon dioxide in biogas under pressure and room temperature conditions in the absorption tower to decarbonize and purify methane. The absorbed rich solution undergoes reverse decomposition reaction under reduced pressure and heating conditions in the regeneration tower, releasing high-purity carbon dioxide gas. At the same time, the rich solution is regenerated and has the ability to reabsorb carbon dioxide, thus realizing the continuous decarbonization and purification of methane in biogas in the absorption tower, and enabling the decarbonization solution to perform continuous absorption and regeneration cycle work

　　工艺优点：CO2去除效果好，CH4回收率高达99%以上，解析气CO2纯度高，无甲烷气，可直接回收利用；该工艺主要适用于大中型沼气提纯项目，该系统稳定性好、操作简单，每年只需补充一定量的化学吸收剂，系统寿命大于15年。

　　Process advantages: Good CO2 removal effect, CH4 recovery rate of over 99%, high purity of analytical gas CO2, no methane gas, can be directly recovered and utilized; This process is mainly suitable for large and medium-sized biogas purification projects. The system has good stability and simple operation, requiring only a certain amount of chemical absorbent to be added each year. The system has a lifespan of over 15 years.

　　工艺缺点：在吸收剂的解析过程需要一定量的蒸汽，由于蒸汽的使用增加了脱碳的运行费用，增加了系统的施工难度。低温冷凝提纯法低温冷凝提纯法是利用二氧化碳液化温度高的特点，通过低温作用使沼气中的二氧化碳被液化，甲烷组分作为不凝气以提纯产品气排出。为了降低运行能耗，通常采用回热技术将剩余冷量进行回收。

　　Process disadvantage: A certain amount of steam is required during the analysis process of the absorbent, which increases the operating cost of decarbonization and the construction difficulty of the system due to the use of steam. The low-temperature condensation purification method utilizes the high liquefaction temperature of carbon dioxide to liquefy the carbon dioxide in biogas through low-temperature action, and the methane component is discharged as non condensable gas to purify the product gas. In order to reduce operating energy consumption, regenerative technology is usually used to recover the remaining cooling capacity.

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