Study On Denitration Technology Of Coal Char Reduction Method

As the main fuel of China's energy consumption,the combustions of coal produce large quantities of pollutants,in which the NO_X is seriously harmful to the environment and human health.It is imperative to control the emission of NO_X from burning coal.Nowadays,there are many methods to control NO_X's emission.One of them is the coal-char reduction method,which is a new economical and feasible technology,has great utilization potentiality in the coal fired boiler system.This article selected commercial semi-coke,commercial coke,and self-prepared semi-coke as the experimental coal-char.Then coal quality and revelent structure parameters of the three coal-chars were analyzed.The denitration reactions were studied in the fixed bed reactor with simulant industrial boiler flue gas.And the influences of char types,reaction conditions,metal ions addition,the composition of flue gas and other factors were discussed on the denitration efficiency.The studies showed that the commercial semi-coke with the properties of low price and good denitrification effect was the most suitable experimental coal in these three coal studied.The commercial semi-coke with the particle size of 0.6¹ mm,had the best denitration effect.When the reaction temperature was 700 ? and space velocity was10000 h-1,the conversion rate of NO could be 99%.When the reaction temperature is between 400? to 600?,the conversion rate of NO gradually reduced as space velocity increased.However,the changes of space velocity had no effect at 700 ?.By adding metal ion,the reduction reaction ability of the deashed semi-coke could be enhanced.The order of three metal ions catalytic activity was K> Ni> Na.Adding 1% K,the conversion rate of NO could be 99.9%.Under anaerobic conditions,the change of NO concentration had no effect on the conversion rate of NO.At the same temperature,NO conversion rate was higher at the presence of oxygen compared with anaerobic situation.NO conversion rate could be up to the highest value with the 4% O₂ concentration.Under aerobic conditions,the change of SO₂ and CO₂ concentration had no effect on the conversion rate of NO.On the basis of experimental research,the denitration reactor was designed for the 20t/h coal-fired boilers.It mainly included process determination,material balance,heat balance,reactor design,material selection,pipeline design,pipe fittings and instrument selection.The commercial semi-coke was consumed by the rate for 98.63 kg/h.Andtemperature rise of the flue gas was 50.9?.The reactor was a cross flow moving bed reactor,which was provided with a shutter gas distributor,triangle component,bin and star unloader.Char reduction denitration process could be simply and easily industrialized.