Experimental Research On NO_x Reduction For Large Scale Coal-fired Boiler Using Staged Combustion

In electric industry, pulverized coal boiler is one of the power equipment which is widely used. It is very important because of its extensive occurrence in industry and in people's living life. People have paid more and more atention to the pollution of environment. And so, the emission of nitrogen oxide of the pulverized coal boilers is also becoming an environmental problem to be solvedAir staged combustion and reburn technology are the popular deNOx technologies used in the world. The NO_x emission from the Jiaxing Power Plant 300MW boiler is reduced through field experiment, by using air-staging theory. The boiler is tangential firing pulverized coal boiler, and the type is SG-1025/18.3-540/540-1. In the field experiment, the concentration of NO_x, carbon content in the flying ash, and the temperature at the outlet of the air preheater are tested at different primary air and second air of different boil load. And through the same experiment with the coal particle diameter changing, the influence rules of different coal particle diameters to the NO_x emission, carbon content in flying ash, and temperature at the outlet of the air preheater of the boil are also obtained. And the boiler is simulated by using "Fluent", a kind of CFD software. The flow, convection and combustion in the boiler are studied and we obtain the velocity distribution, temperature distribution and the NO_x distribution in the boiler. Based on this, we forecast the feasibility of using micronized coal reburning to decrease NO_x.This paper concludes that: the NO_x could be decreased by using air-staging, and the more staging intensity, the lower NO_x amount is. The NO_x decrease proportion reaches 24% at the best air-staging condition. Using micronized coal can decrease more NO_x at air-staging condition. In existence boiler equipment, air-staging is a more effective technique than micronized coal reburning in NO_x emission reduction.