1. Biogas dry desulfurization technology was applied earlier. The dry desulfurization technology applied to biogas is iron oxide desulfurization technology with biogas iron ore as desulfurizer. Later, with the successful research of biogas desulfurization iron oxide and the relative reduction of production cost, iron oxide desulfurization technology also began to be widely used.
2. The iron oxide desulfurizer used in iron oxide desulfurization technology is biogas iron ore and artificial iron oxide. In order to increase its porosity, the desulfurizer is made by using wood chips as filler, spraying an appropriate amount of water and a small amount of hydrated lime, and repeatedly turning and drying. Its pH value is generally about 8-9. This kind of desulfurizer has low desulfurization efficiency and must be regenerated outside the tower. It is difficult to regenerate. It will soon be replaced by other desulfurizer. At present, TF desulfurizer is widely used. This desulfurizer has high desulfurization efficiency and can be regenerated in the tower.
The main mechanism of iron oxide desulfurization is catalysis and adsorption. When the gas containing H2S passes through the iron oxide bed, exothermic reaction occurs under normal pressure, and it is catalytically oxidized to elemental sulfur ions on the surface of iron oxide, and its products are adsorbed by iron oxide to achieve its desulfurization purpose. In order to meet the needs of users, this scheme adopts single tower operation. After running for a period of time, the tower packing has been saturated, lost desulfurization capacity and needs to be replaced. During replacement, purge the desulfurization tower with steam until the gas is tested to be qualified, open the manhole and discharge hole and replace the filler. Gas sampling nozzles are set at the inlet and outlet of the tower for testing and sampling.
3. Due to the high water content of biogas, some water will accumulate at the lower part of the desulfurization tower during operation. During normal operation, operation shall be carried out at regular intervals. Biogas flows out from one end of the desulfurization tower after being purified by the packing layer (mainly composed of activated carbon and iron oxide) and from the other end. Hydrogen sulfide reacts with iron oxide in the filler layer to form iron sulfide; Regeneration can be carried out after the iron oxide reaction is completed.