Effects of co-combustion of semi-coke and biomass on emissions and combustion characteristics of NOx and SO2
The co-combustion of biomass and semi-coke is considered to be a potential way to solve a large number of air pollution-related problems such as carbon emissions,NOx and SO2.The air-staged combustion characteristics of semi-coke,mixture of semi-coke and bio-mass were studied by thermogravimetric experiment and drop tube furnace experiment respectively.The effects of blending ratio on ignition temperature,burnout temperature,slagging characteristics,fouling characteristics and combustion characteristic index of mixed fuel were analyzed,and the suitable air-staged combustion ratio,optimal combustion temperature and optimal blending ratio were determined.The results show that the ignition point of the mixed fuel is effectively reduced after co-firing biomass,and the ignition point is reduced from 474 ℃ to 300 ℃.The burnout temperature is slightly reduced after co-firing biomass.The combustion characteristic index is not signifi-cantly improved by the combustion of carbon mixed biomass.The combustion of biomass mixed with carbon powder has a tendency of high ash deposition and a small tendency of slagging.The outlet NOx mass concentration and outlet SO2 mass concentration after co-firing bio-mass at different temperatures are lower than those before co-firing.Compared with those before co-firing,the mass concentration of outlet NOx and SO2at 1 200 ℃ decreases significantly,reaching by 87.27％and 80.2％respectively.Based on comprehensive export parame-ters such as NOx,the optimal biomass mass fraction is 30％～40％,and the optimal combustion temperature range is 1 200～1 300℃un-der the condition of no air classification.The initial NOx emission of biomass with a mass fraction of 30％changes gently with temperature during staged combustion,showing good stability.The outlet NOx mass concentration is the lowest,all below 125 mg/m3.The re-search conclusions can provide some technical support for the equipment operation of organic solid waste incineration disposal and the or-ganizational regulation of related combustion conditions.
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