| The emission of pollutants emitted from the flue gas of residential coal stoves is one of the main contributions to atmospheric pollution.In recent years,biomass molding fuel and supporting biomass stoves have been vigorously promoted as an alternative path for clean heating.This study conducted laboratory and field tests on biomass stoves,analyzed the pollutant emission factors affecting biomass stoves,and evaluated the current status of pollutant emission reduction of biomass stoves equipped with wood pellets and straw pellets.The average emission factors of CO,PM2.5 and NOx in the laboratory test of biomass water heating stoves and biomass radiant stoves are 12.75 ± 5.73 g/kg,0.49±0.24 g/kg,3.17±0.53 g/kg and 2.85±3.52 g/kg,0.24±0.14 g/kg,3.09±0.37 g/kg.Compared with biomass water heating stoves,the emissions of CO,PM2.5 and NOx from biomass radiant stoves can be reduced by 77.65%,51.02%and 2.52%respectively.Intermittently feeding biomass stoves can reduce CO and PM2.5 emissions by 45.57%and 29.73%,respectively,compared to continuous feeding biomass stoves.Compared with biomass stoves without secondary air,the emissions of CO and PM2.5 of biomass stoves with secondary air devices can be reduced by 57.94%and 37.50%,respectively.Low-power combustion can reduce PM2.5 emission,but will increase CO emission.The emissions of CO and PM2.5 decreases firstly and then increases with the increase of excess air coefficient.The optimal excess air coefficient in this study is α=2.4.The emission factors of the stoves tested in the field are much higher than those tested in the laboratory.The field tests and laboratory tests of EFCO,EFPM2.5,and EFNOx for the radiant stoves are 18.53±9.5 g/kg,2.25±1.22 g/kg,3.64±1.33 g/kg,and 2.21±0.51 g/kg,0.22±0.09 g/kg,2.95±0.33 g/kg.The field tests and laboratory tests of EFCO,EFPM2.5,and EFNOx for the water heating stoves are 28.11±1.66g/kg,2.35±0.23 g/kg,7.53±2.30 g/kg and 19.40±4.52g/kg,0.45±0.14 g/kg,3.68±0.34 g/kg.In the field test,in the wood pellet biomass stove promoted by a county in Binzhou City,Shandong Province,the CO and PM2.5 emissions of the gravity-fed radiant stove were reduced by 74.51%and 63.73%,respectively,compared to the raw coal stove.Compared with raw coal stoves,the CO emissions of power-fed stoves can be reduced by 35.22%.The high fuel consumption of biomass water heating stoves will increase the total annual emissions,no obvious emission reduction effect has been found.More careful evaluation is required before mass-promoting biomass stoves.Among the straw pellet biomass stoves promoted by a county in Suihua City,Heilongjiang Province,the combustion performance of the automatic feeding biomass stove is better than that of the manual feeding biomass stove.Compared with raw coal stoves,the reduction ratio of PM2.5,CO,and SO2 of automatic feeding biomass stoves is 39.79%,52.77%(P=0.008,<0.05),41.35%,respectively.The reduction ratio of PM2.5,CO,and SO2 of manual feeding biomass stoves compared to raw coal stoves was 33.41%,19.38%(P=0.035,<0.05),27.01%,respectively.The nitrogen content in biomass fuel is high,therefore biomass stoves have no significant effect on reducing NOx emission. |
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