Biogas power generation schematic anaerobic digestion device output of biogas is mixed gas containing saturated steam, in addition to containing inert gas CO2 and CH4 gas fuel, also contain a certain proportion of H2O, H2O, a small amount of NH3, H2 and N2, O2, CO, and halogenated hydrocarbons.
The biogas purification refers to other than CH4 gas in the gas removal.
In summary, at present there are three types of biogas purification methods, namely, chemical absorption, physical purification and biological removal.
1, chemical absorption.
A chemical absorption mechanism is to use an amine, alkali, alcohol and absorbent composite solution, using the acid and alkali neutralization reaction to absorb CO2 and H2S in the gas acidity material, but also can absorb NH3 and other soluble in water, alcohol gas.
Another kind of chemical absorption mechanism is to use dry chemicals (
Such as Fe2O3)
As absorbent to absorb impurity gas.
Chemical absorption absorber can be through the device of self-purification system release and regeneration system using various impurities and gas recycling.
2, physical purification.
Through this mechanism of biogas purification, the mainly method of pressure swing adsorption (psa).
Using adsorbent in different pressure conditions on the principle of different gas adsorption force to separate different components of methane.
H2O and CO2 and H2S in gas adsorption capacity of the larger components of strong adsorption by adsorbent adsorption under pressure to stay in bed, while smaller N2, CH4 adsorption capacity of weak adsorption components & ensp;
Such as export output from bed to achieve the purification of biogas.
3, biological removal.
To grow in the certain conditions using microorganisms need some impurity gas in the biogas as nutrients, so as to realize the purification of biogas.
At this stage, the physical and chemical method has been widely used and has accumulated rich experience, but the method of the high cost of operation and investment big, the regeneration difficulty, shortcomings and so on to produce secondary pollution.
Biological method needs no catalysts and oxidants, do not need to deal with chemical sludge, less pollution, low energy consumption, high efficiency, and the advantages of elemental sulfur recycle, is becoming a development trend in the field of gas desulfurization.