Technology And Economic Research On CFB Boiler Deep Desulfurization

Hundreds of circulating fluidized bed (CFB) boilers had been running in china by the advantages of wide fuel adaptability, low pollutant emissions, better load regulation performance and so on. However, with the increasingly stringent environmental standards layed down, whether CFB boiler can meet the requirements or not, it is still a controversial.In this paper, to acquire the actual effect of desulfurization in furnace, we do some tests of the main power plant CFB boilers in Guangdong province with the Guangdong Power Grid Electric Power Research Institute. The results illustrated the desulfurization efficiency is not so high in actual plant operation, and the concentration of SO2 fluctuated too large. Although throw a lot of limestone, it is meet the requrirements difficult. And also result in low utilization of limestone, and cause some negative impact on combustion. In order to meet the current stringent SO₂ emission requirements better, we propose the concept of deep desulfurization.In the paper, Guangdong Yun Fu power plant CFB boiler abandoned desulfurization in furnace but adopted wet flue gas limestone/gypsum deep desulfurization technology, which was the world's first example for CFB coal-fired boiler desulfurization. The designed emission standard is 209.6mg/Nm3.Tthe power plant tests showed that when the Ca/S molar ratio was 1.03, the average desulfurization efficiency up to 96.7% and the operation was stable. Although wet flue gas limestone/gypsum desulfurization has the advantages of high desulfurization efficiency, high reliability and the technology is also mature, the desulfurization cost is very high. In addition, when burning higher sulfur coal, flue gas wet limestone/gypsum deep desulfurization was unable to meet the requirements.Therefore, we proposed the technology combined desulfurization in furnace with wet flue gas limestone/gypsum deep desulfurization, and did some economic and feasible analysis for it. At last, based on the program of combined-deep desulfurization in furnace and flue gas desulfurization, we studied the main factors for deep desulfurization allocation like different original SO₂ concentration, the price of limestone and byproduct gypsum price in different emission standards.The results show that CFB coal-fired boiler desulfurization in furnace+wet flue gas limestone/gypsum deep desulfurization technology is feasible, and also a better desulfurization mode to meet more strict environmental requirements. It has important guiding significance for CFB boiler desulfurization in the future by study on the subject.