The flue gas of biomass boiler belongs to the flue gas with low SO2 concentration. The commonly used methods are calcium spraying in the furnace, circulating fluidized bed spraying calcium (calcium spraying outside the furnace), wet desulfurization technology outside the furnace.All the schemes can meet the emission requirements, and cost control is the key. The operation costs of the double alkali method, ammonia method and magnesium method in wet desulfurization are relatively low. The ammonia method directly produces ammonium sulfate fertilizer, which can be mixed with the ash collected by dust collector to form compound fertilizer and return to farmland.But double alkali method, magnesium method produces mixed salt treatment has a piece of difficulty.
1. Integrated technology of wet desulfurization and denitration
Adopting O3 denitration scheme, ammonia water is selected as desulfurization absorbent for wet desulfurization. After the pollutants are absorbed and oxidized, agricultural fertilizers such as ammonium nitrate and ammonium sulfate are generated.
2. Semi-dry desulfurization and denitration integration technology
The O3 denitration scheme is adopted, and the dry desulfurization method uses the circulating fluidized bed outside the furnace to spray calcium. After the pollutants are absorbed and oxidized, the products are generated as calcium nitrate, calcium nitrite, calcium sulfate and calcium sulfite. The desulfurization and denitration products enter the bag dust collector with the flue gas and finally discharge into the ash slag system.