The selection of desulfurization technology route in biogas purification and refining natural gas should focus on hydrogen sulfide concentration, treatment scale, concentration fluctuation range and treatment cost. When the concentration of hydrogen sulfide is high and the treatment scale is large, alkali washing biological regeneration desulfurization technology and alkali washing catalytic regeneration desulfurization technology are easy to be used. Compared with the latter, the latter is lower in terms of operation cost, but in terms of resisting the impact of concentration change, the latter is better than the former, and in terms of investment, the latter is also better than the former.
Biological desulfurization process is a new type of desulfurization process, which is more and more welcomed by enterprises. The basic principle of biological desulfurization is to synthesize hydrogen sulfide and oxygen into sulfate and then remove hydrogen sulfide from biogas by utilizing the metabolism of microorganisms of Thiobacillus and sericin, and the desulfurization product is sulfate.
Although its use is relatively convenient and its operation cost is low, because impurity gas is introduced in the desulfurization process at the same time, it can not be removed in the subsequent process. At the same time, biological desulfurization has just started and the technology is not mature. Most of them use imported technology and equipment, so the investment cost is relatively high, about 3-5 times as that of conventional dry desulfurization.
In recent years, a small number of domestic enterprises and scientific research institutions have cooperated to study, according to the characteristics of biogas projects and hydrogen sulfide in biogas, a large number of fruitful improvements and improvements have been made to the alkali washing catalytic regeneration desulfurization technology, especially to solve the problems of high concentration hydrogen sulfide removal such as blocking tower, poor regeneration effect and difficulty in extracting elemental sulfur.
Dry desulfurization, PSA and membrane desulfurization are mostly suitable for refined desulfurization after initial desulfurization of hydrogen sulfide, or for biogas refining projects with small gas volume and low concentration of hydrogen sulfide. Although biological desulfurization has low operation cost, it is not suitable to be applied in the field of biogas refining natural gas because of the introduction of a large number of impurity gases such as nitrogen and oxygen.