Study On Combustion Characteristics And NO_X Emission Of Mixed Combustion Of Coal And Biomass In Dropper Furnace

With the development of social economy,the environmental problems caused by the increasing consumption of fossil energy are becoming more and more serious,which has aroused people's extensive attention.To solve this problem,researchers have proposed a variety of combustion methods.Among them,biomass and coal burning is one of the effective means to reduce coal consumption and pollutant emissions.Biomass has the advantages of high combustion efficiency,and its pyrolysis products can have chemical reaction with NO_X to reduce its emissions,etc.,but its calorific value is low,and it is easy to coking in the combustion process.Therefore,in this paper,the combustion and NO_X emission characteristics under different influencing factors were studied in detail for the mixed combustion process of biomass and coal.First of all,this paper built three regional independent temperature control dropper furnace test bench.Secondly,based on TGA,the combustion characteristics of different biomass and coal mixtures are studied.It was found that there were two peaks in the DTG curve of weight loss rate changing with temperature in the combustion process of three kinds of biomass and bituminous coal,representing the volatilization process of volatiles and the combustion process of biomass.The DTG curve of weight loss rate changing with temperature in the combustion process of anthracite has three peaks,and the extra peak is due to the small volatiles and large residual solid content of anthracite,which appears near the ignition point of anthracite and corresponds to the combustion process of anthracite.The maximum rate points in the combustion process all appear near the ignition temperature of biomass,indicating that the addition of biomass energy can advance the maximum combustion rate in the mixed combustion process ahead of the pure coal,make the burnout characteristics and combustion efficiency of the whole combustion process greater than the pure coal,and reduce the harm caused by excessive coking caused by the single combustion of biomass.Finally,based on the established dropper furnace test bench,NO_X emission characteristics under the combined action of these factors were studied by controlling excess air coefficient,oxygen concentration,biomass content and combustion atmosphere.The main experimental conclusions are as follows:Under the condition of lower oxygen concentration and higher biomass content,less NO_X is produced by mixed combustion.The ignition point of seagrass is far lower than straw and wood chips,and it will burn in advance,and its nitrogen content is high,and the mixed combustion produces the most NO_X,but the difference between wood chips and straw is not large.Choosing wood chips,straw and pulverized coal can effectively reduce NO_X emission.