生物质炉具现场测试污染物排放特征及减排效果评估

目前对于生物质成型燃料替代散煤减排效果的现场评估还非常缺乏,且均为基于短时间测试方法,无法反映炉具全天实际排放情况。该研究以黑龙江省某生物质成型燃料及配套炉具推广示范村为例,采用全天24 h实地测试的方法,研究了该地区的燃煤炉具以及推广的自动进料和手动进料生物质炉具的污染排放情况。结果表明:自动/手动进料生物质炉具相比燃煤炉具的PM_(2.5)、CO、SO_2排放因子分别降低41.2%、54.3%、40.0%和35.3%、22.1%、20.0%,NO_x的排放因子没有降低。对不同取暖方式的户均排放总量核算发现:自动/手动进料生物质炉具排放的PM_(2.5)、CO、SO_2分别减排39.79%、52.77%、41.35%和33.41%、19.38%、27.01%;NO_x分别升高46.14%和6.69%。此外,调研发现经济性和便利性是生物质炉具推广的重要影响因素。

Field evaluation of pollutant emissions and reduction effects of biomass pellets burning in improved heating stoves in rural China

Biomass pellets burning can improve the efficiency of heating stoves, compared with traditional raw coal, thereby to achieve clean heating in rural areas of China. Most previous studies focused on short-term testing, which cannot reveal the actual emission of stoves the whole day. The current on-site measurements on pollutant emissions are still lacking. Taking a demonstration village of biomass pellets and supporting stoves in a county of Heilongjiang Province as an example, this study aims to investigate the pollutant emissions of biomass pellets using 24-hour field measurement method, and further to evaluate the emission reduction effect, when using biomass pellets to replace raw coal for heating. A portable residential stove on-site pollutant emissions testing system was used, particularly equipped with real-time sensors to measure the emissions of CO, CO2, SO2, NOx and PM2.5. A dilution channel was also equipped, including a PM2.5 cyclone, and the filter loading compartments for PM2.5 collection. The dilution sampling method was used to simulate the process of high-temperature mixing smoke from the exhaust chimney in atmosphere. This system can effectively record the entire combustion of residential stoves, and the pollution emissions 24 hours a day, while in-situ monitor the actual pollution emission levels of residential stoves. The results showed that the emission concentration of pollutant that emitted from the combustion of biomass stoves relatively fluctuated less than that of raw coal stoves. The emission factors of pollutant from raw coal stoves and manual/automatic feeding biomass stoves were 0.17 g/MJ, 0.11 g/MJ, 0.10 g/MJ for PM2.5; 5.54 g/MJ, 4.32 g /MJ, 2.53 g/MJ for CO; 0.05 g/MJ, 0.04 g/MJ, 0.03 g/MJ for SO2, and 0.08 g/MJ, 0.08 g/MJ, 0.11 g/MJ for NOx. The emission factors of PM2.5, CO, and SO2 from the automatic and manual feeding biomass stoves reduced by 41.2%, 54.3%, 20.0%, and 35.3%, 22.1 %, 40.0%, respectively, compared with the raw coal stove. In contrast, the NOx emission factor of automatic feeding biomass stoves increased by 37.5%. The total amount of pollutant was calculated from the different combinations of stoves and fuel, in order to evaluate the emission reduction effects of pollutant from two biomass stoves. The results showed that: compared with raw coal stoves, the reduction ratio of CO, SO2, and PM2.5 emission in the manual feeding biomass stove were 19.38%, 27.01%, and 33.41%, respectively, where the reduction effect of CO emission was significant (P<0.05). The reduction ratio of pollutants CO, SO2 and PM2.5 that emitted from the automatic feeding biomass stove were 52.77%, 41.35% and 39.79%, respectively, in which the reduction effect of CO emission was also significant (P<0.05). However, the total average household amount of NOx that emitted from the automatic and manual feeding biomass stoves increased by 46.14% and 6.69%, respectively, compared with the raw coal stove. Surveys and interviews were conducted with residents in areas, where biomass clean stoves were promoted. It was found that the publicity of environmental protection and technical training for residents have become urgent to promote the utilization of such biomass stoves, and thereby to ensure the effective implementation of clean heating policies.