Experimental Study On NO Formation During Combustion Of Zhundong Coal And High Temperature Pyrolytic Gas

In recent years,many cities in China appeared haze and O3 over standard in summer,NO emission is an important factor in the formation of photochemical smog.In 2005 the exploration of the Zhundong coalfield confirmed it contains 3900 hundred million tons of coal resources,which can meet China's one hundred years of use.The coal quality of the Zhundong coal is shown as: high moisture and volatile content,low ash and heat value,the rate of iron and sodium in ash is high.Due to the lack of accurate understanding of the coal quality characteristics of Zhundong coal,the problems such as settling slag,contamination of the high temperature heating surface and instability of the original NO emission appeared during the power plant's burning of Zhundong coal in the early times.Studying on the formation of NO during Zhundong coal combustion,especially volatile combustion,is of great significance to the development of low nitrogen combustion technology based on the Zhundong coal.In order to separate the pyrolytic gas during coal pyrolysis and burn it alone,a drop tube furnace was designed in this paper.Taking Zhundong coal as the research object,the effects of pyrolysis and combustion conditions on the transformation of N elements in coal were analyzed.A portable FTIR is used as the mainly analysis instrument,the concentration of NH3 and HCN in pyrolystic gas which produced in three carrier gases Ar,CO 2 and N2 at 1100?,1250?,1400? was studied.The results show that the concentration of NH3 and HCN in pyrolytic gas decreases with the increases of temperature;in N2 carrier gas,the concentration of NH3 and HCN is the highest,in Ar carrier gas is lower,and in CO2 carrier gas is the lowest.Changing O2 supply conditions in order to burn the pyrolytic gas simultaneously,research the law of NO generation during pyrolytic gas combustion in the atmosphere which contains 5% ? 10% ? 20% ?30%volume concentration of O2 with the corresponding carrier gas.The results show that the concentration of NO produced by combustion of pyrolytic gas increases with the increase of temperature and O2 concentration;the highest concentration of NO is released by pyrolytic gas burnt in the N2 carrier gas,the lower in the Ar carrier gas,and the lowest in the CO2 carrier gas.That is related to the effect of carrier gas during pyrolysis and combustion process.Taking the combustion experimental of Zhundong pulverized coal under the same conditions of pyrolytic gas combustion,in order to research the NO generation concentration during pulverized coal combustion.The results show that the concentration of NO released by pulverized coal combustion increases with the increase of O2 concentration.The effect of temperature on the release of NO concentration in pulverized coal combustion is different in different carrier gas,the amount of NO is greater when the temperature is higher in N2 carrier gas;the concentration of NO in Ar and CO2 carrier gas increases first and then decreases with the increase of temperature.As NO concentration in pulverized coal combustion in different carrier gases,when in N2 carrier gas is highest,Ar carrier gas is next,and CO2 carrier gas is lowest.The relative contribution of NO released by c ombustion of pyrolytic gas in coal combustion process was analyzed.The results show that the increase of temperature can increase the rate of NO released by combustion of pyrolytic gas.The ratio of carrier gas and O2 concentration to the release of NO from pyrolytic gas combustion is relate to temperature,and shows an interactive influence.