Research Of SNCR Denitrafition For 300MW CFB Boilers

Circulating Fluidized Bed Combustion can effectively control the concentration of NOx by low temperature burning and multi-stage-burning technology. According to the new emission standard passed in 2011 in China,the NOx emission concentration of CFB boiler must be less than 200mg/Nm3.It was necessary to take measures to further reduce NOx emission in CFB boiler. In this paper, 300 MW CFB boiler in a certain power plant is taken as an example to research SNCR denitrafition technology. With the burning of non-designed coal, sometimes, the Emissions of NOx in CFB may exceeds emission standard. After a comparative analysis between SCR and SNCR scheme,SCR was selected. As a reducing agent, Urea is sprayed into the inlet flue duct of Cyclone Separator to cause Selective Non-Catalytic Reduction Reaction with NOx under high temperature. It can reduce the emission of NOx effectively. In full-load condition,the NOx emission was 62.83 mg/Nm3,and the denitrification efficiencies can reach 75.17%. Meanwhile,the NOx emission was less than 140 mg/Nm3 by effective control in low-load condition. After renovation, the efficiency of boiler just decrease 0.1% and the air leakage rate of air preheater remained fairly flat. The practice proves that it can make the NOx emission concentration reach new Chinese standard and get remarkable social economical benefits by denitration transformation in CFB boiler.