Research On The Cofiring Of Syngas From Biomass Gasification And Coal-fired Boiler

China’s energy market is dominated by coal. The industrial boilerconsumes about500million tons of raw coal annually,however,environmental pollution from the industrial boiler is very rampant.Therefore,there is a very important practical significance of research onlow-NOx combustion technology for coal-fired industrial boilers.65%ofthe industrial boiler are the traveling grate boilers and the way ofcombustion is large granular coal burning, which makes the travelinggrate boiler study has its own unique aspect. Among the coal-fired boilerNOx emission control technologies, fuel reburning technology, namely inthe boiler furnace using secondary fuel as a reducing agent for reducingNOx emissions technology, has initiated extensive researchers.In this paper, biomass gasification syngas is reburning on layerburning stove bench to reduce NOx to simulation chain furnace NOxreduction. Firstly, we arranged the generation and reduction mechanismof NOXat home and abroad. And then we built up the layer combustionunit furnace experiments, the gasification boiler and the cofiring system.Then specific experiments are made for the characteristics of the unitbody furnace NOx formation, the character of gasification boiler, and therule of cofiring of coal and syngas, to make sure the right temperature,the right residence time, the right stoichiometry for the high efficient NOXreduction.Though the layer combustion unit furnace experiments, we foundthat: the big excess air can speed up the flame front downwardpropagation, accelerate the combustion rate and volatile, form strongreduction atmosphere in the combustion stage which is good for reducing NOX; in the early stage of volatile combustion phase, the NOXrelease ofbigger particle size is lower, but at the later stage of the char nitrogenrelease the bigger one is higher; the delayed combustion can greatlyreduce NOx emissions in a volatile region and burning serious area butwith less effect in burnout stage.Though the cofiring research experiments on the platform, we foundthat: the cofiring of biomass gasification gas on the layer combustion unitfurnace had a certain effect on NOXreduction; the reduction was better inthe volatile-out and burning serious region of the coal layer, while thereduction is weak in the burnout zone; when the biomass gas was more,the reduction was the better, but the reduction efficiency and biomassvolume increase was not linear relationship; in the staged combustioncondition, cofiring could effect more in the first10minutes with littleexcess oxygen than the late stage; in the direct combustion, the higher ofthe oxygen, the reduction effect was less, so we should try to reduce theconcentration of oxygen in cofiring with biomass syngas; the reaction ofbiomass gas reduction NOXwas very fast, so the reduction efficiencydidn’t change significantly when we changed cofiring position.