Experimental study on the gasification-combustion characteristics and nox emission characteristics of pulverized coal
Coal powder gasification combustion technology is an important way to achieve ultra-low load stable combustion and low nitrogen oxide(NOx)emissions in coal-fired boilers.To determine the effect of primary wind speed(λ1)on the gasification combustion characteristics and NOx emissions of coal powder.A study was conducted on a self-built counterflow fluidised bed gasification combustion system λ.The reactivity and pore structure of the gasification semi-coke were analysed using a thermogravimetric analyser(TGA)and a chemical adsorption instrument to investigate the impact on the coal gasification characteristics,fuel nitrogen conversion and NOx emission characteristics.The results indicate that the increase of λ1 would increase the temperature of the gasifier,reducing the concentrations of CO and CH4 at the outlet of the gasifier by 2.67%and 2.43%,respectively;Promoted the conversion of fixed carbon,with a conversion rate increase of 17.28%;The conversion of fuel-N increased by 13.50%,with an increase in conversion to N2 but a decrease in conversion to NH3.Meanwhile,λ1 increasing the pore structure of gasification char resulted in a more developed pore structure,with an increase in specific surface area of 95.77 m2/g and a 2-fold increase in pore volume,which improved the combustion characteristics.After the gasified fuel enters the combustor,when λ exceeds 0.25,no NO is generated in the main combustion zone of the combustor.When λ1=0.35,the pollutant emissions at the combustor outlet are the lowest,with NOx and CO at 115.86 mg/Nm3(@6%O2)and 39.25 mg/Nm3(@6%O2),respectively;mean-while,the combustion efficiency is the highest,with the value of 99.68%.Therefore,primary air has a significant effect on the combustion characteristics and pollutant emissions of pulverised fuel gasification.By controlling an appropriate amount of primary air,pollutant emissions could be reduced while improving combustion efficiency.
国家科技期刊平台
NSTL
万方数据
