Different from the conventional vertical air-staging technology in the coal-fired grate boiler,a horizontal air-staging technology is put forward,in which the primary-air feeding is decreased under the flame zone and the recirculating flue gas is fed from the side wall to create a strong reducing atmosphere near the grate in order to reduce fuel NOx emission.The technology was implemented on a 46 MW coal-fired grate boiler.The experimental results showed that the flame was postponed along the grate in the combustion chamber.The position of the peak temperature was extended from 2.62 m to 3.52 m distanced from the inlet,and a reduction zone with high CO concentration appeared.The peak concentration of NOx on the grate decreased from 535 mg/m3 to 322 mg/m3.And the NOx concentration in flue gas is reduced from 350 mg/m3 to about 260～290 mg/m3,achieving de-NOx efficiency of 17.1%～25.7%.Furthermore,the burn-out level of final dis-charged slag is not impacted.The new technology is significant to achieve the realization of deeply NOx emission control in grate-firing furnace.
grate-firing boilerair stagingflue gas recirculationNOx concentration
万方数据
维普
