With the development and utilization of renewable energy in China, anaerobic fermentation of livestock and poultry manure to produce biogas is a very promising way of energy utilization, but the biogas produced contains H2S gas. As it is a highly corrosive compound, biogas desulfurization is the key link of biogas utilization. In this paper, the bio-desulfurization technology in large-scale biogas project is analyzed based on an engineering debugging and operation example, which can provide reference for similar projects.
At present, there are two kinds of methods for biogas desulfurization, namely physical chemical method and biological method. Physicochemical methods, including dry desulfurization and wet desulfurization, have been widely used and accumulated abundant experience, but they have disadvantages of high operating costs, large investment and secondary pollution. Biological methods have attracted wide attention for their advantages of no catalyst and oxidant, no chemical sludge treatment, less pollution, low energy consumption, high efficiency and recoverable elemental sulfur. 。 For this reason, taking the biogas project of a company as an example, the specific application of bio-desulfurization technology in debugging and operation of the biogas project is introduced.
生物脱硫的装置主要由生物脱硫塔和曝气水箱构成，从厌氧罐内导出的沼气由脱硫塔底部进入，脱硫循环水由泵打入脱硫塔顶，两者在塔内逆向接触反应，且塔内充有填料以供脱硫菌附着生长，同时也利于气水均匀分布以充分接触。生物脱硫塔及曝气水箱都采用耐酸玻璃钢制作，循环泵也使用耐酸性泵。脱硫塔的负荷为8m3 (沼气) /（m3·h）左右。
The device of biological desulfurization is mainly composed of biological desulfurization tower and aeration tank. The biogas derived from anaerobic tank enters from the bottom of desulfurization tower, and the circulating water of desulfurization is pumped into the top of desulfurization tower. Both react in reverse contact in the tower, and the tower is filled with fillers for the attachment and growth of desulfurization bacteria, which is also conducive to the uniform distribution of gas and water for full contact. Biological desulfurization tower and aeration water tank are made of acid-resistant FRP, and circulating pump is also made of acid-resistant pump. The load of the desulfurization tower is about 8 m3 (methane) / (m3.h).
Biological desulfurization is used to desulfurize biogas in this project. H2S is oxidized to elemental sulfur or sulfite mainly by the metabolic action of colorless sulfur bacteria under suitable temperature, humidity and micro-oxygen conditions. Biological desulfurization can be divided into three stages:
1. The dissolution process of H2S gas, i.e. from gas phase to liquid phase;
2. The dissolved H2S is absorbed by microorganisms and transferred to microorganisms.
3. As nutrients, H2S entering microbial cells is decomposed, transformed and utilized by microorganisms to remove H2S.
Although biological desulfurization has the characteristics of low energy consumption and high removal rate, it is necessary to create a suitable environment for sulfur bacteria to ensure their high biological activity in order to achieve the best desulfurization effect.
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