Evaluation And Analysis On The Performance And Emissions Redution Of Residential Heating Stoves

In the rural area of China,the residential use of low-efficiency heating stoves and solid fuel for heating in winter is one of the important causes of air pollution.Promotion on efficient stoves and clean fuels is beneficial to energy conservation and emission reduction,as well as improving air quality in China.Current heating status of rural area is unclear,including heating equipments,coal consumption,and user demand and so on.Less researches are conducted on the combustion and pollution emission characteristics of heating stoves,and lack of follow-up assessment on the promotion of improved heating stoves.Therefore,user surveys,laboratory tests and field tests of typical stoves and fuels were conducted in this study.According to the user survey,a large number of inefficient domestic heating stoves and bituminous coal are being used for heating in rural area.Among the 93 million scattered heating households,coal-fired heating accounts for more than 70%,and the efficient heating stoves market share was only 23%.Users have low purchasing power for improved stoves and clean fuels,and their purchase channels are narrow.More than 90%of users rely on stores and government promotion.Operating costs of Coal to electricity and coal to gas are more two times than heating stoves.Laboratory tests were conducted on fuels such as coal briquette,semi-coke,processed bituminous coal,and biomass molded fuels,and specified improved stoves.The heating efficiency of the clean fuels burned in improve heating stoves can reach about 70%,and pollutant emision concentrations can generally meet the national standards.Affected by stove design and fuel characteristics,the SO2 emission concentrations of coal-fired stoves are higher,and the concentrations of NOx from biomass stoves are higher.The SO2 emission concentrations of coal briquette stoves and semi-coke stoves are 139.7 ± 66.4 mg/m3 and 192.4 ± 99.6 mg/m3,respectively,exceeding the standard limit of 100 mg/m3.PM2.5 and SO2 for bituminous coal stoves are 56.6 ± 11.4 mg/m3 and 137.6 ± 38.5 mg/m3,respectively,which exceeded the standard values.Biomass-fired stoves could greatly reduce the SO2 and PM2.5 emission concentrations,and the NOx concentration was severely exceeded.The NOx emission concentrations of biomass pellet stoves and biomass briquettes stoves were severely exceeded,being 166.2 ± 80.5 mg/m3 and 645.1 ± 88.8 mg/m3,respectively.The field test selected three demonstration sites of improved heating stoves specified for semi-coke,biomass pellets and firewood for investigation and measurement.Compared to conventional bituminous coal heating,stove heat efficiency can be increased,but fuel consumption is not significantly reduced.User operation activities have a great impact on stove combustion and emissions,and the MCE value of high-power phase is significantly higher than smoldering phase.The PM2.5,SO2,and NOx emission concentrations during high-power phase are more than 20 times that of the smoldering phase.Promotion of improved stoves and clean fuels cannot fully reduce all pollutant emissions,and some pollutant emission factors and total emissions may increase.In the field test,compared with the bituminous coal heating,the semi-coke stove can reduce the total household emission of PM2.5 and SO2 by 56%and 60%respectively,and the CO and NOx increase by 183%and 28%.Straw pellets stove can reduce CO and SO2 emissions by 56%and 60%respectively,and the PM2.5 and NOx increase by 183%and 28%.Biomass stoves can reduce CO emissions by 70.3%instead of coal stoves,however,TSP may increase 2.8 times.Large-scale clean stove promotion projects need to be carried out with caution.