生物质混燃在农村能源供应中应用分析

Application of Biomass Co-combustion in Rural Daily Energy Supply

通过对比生物质、燃煤及两者1∶1的混合燃料在燃煤炉具中采暖及炊事两种工况下的能量效率、排放特征及经济性能,具体量化生物质混燃的技术优势,为清洁低廉的生物质能在农村地区的推广提供理论依据。结果显示,在燃煤炉具中混合燃料燃烧时的能源效率明显高于生物质燃料,且其采暖工况效率高于炊事工况效率近20%。相比于燃煤,混燃时主要气态污染物SO2、NO、NO2综合减排效果良好,PM2. 5排放量远低于国标限值(100 mg/MJ)。其主要有机污染排放PAHs也能得到有效控制,尤其是高环PAHs在采暖和炊事工况下的减排率可分别达到34%和87%。而相比于生物质,混燃时CO排放较少,在采暖工况下减排率为46%,炊事工况则为61%。此外由于人为操作较少,采暖工况下的污染排放量较为稳定。混合燃料价格较低,单位能量价格为0. 039元/MJ,而单位质量价格仅为燃煤的1/2,燃烧器可使用低成本燃煤炉具,避免使用价格昂贵的生物质专用炉具,可确保低收入家庭居民日常用能支出维持在经济承受能力范围之内。

China has abundant biomass equal to over four million tons of standard coal,which can directly substitute coal in residential energy system. The focus was to quantify performances of household biomass co-combustion by comparing energy efficiency,emission characteristics and economic value of biomass,coal and co-fuel in a typical coal-burning stove under space-heating and cooking phase to promote clean and cheap biomass energy in rural areas. The results indicated that energy efficiency of cofuel was much higher than that of biomass in coal-fire stove with a value of 68. 10% in heating phase and54. 50% in cooking phase. The gaseous pollutant of SO2,NO and NO2 emitted from co-combustion were reduced significantly compared with coal burning,and PM2. 5 was decreased to a low concentration which was much lower than the limiting value(100 mg/MJ) of Chinese standard. The emission reduction of SO2,NO,NO2 and PM2. 5 was 22%,67%,88% and 18%,respectively,in heating phase,while the reduction emission was 11%,64%,63% and 33%,respectively,in cooking phase. The organic emissions of US-EPA priority PAHs with high carcinogenicity were also controlled well and the emission reduction of high-ring PAHs could reach 34% and 87% in heating and cooking phases. Compared with biomass in coal-fire stove,the emission of CO from co-fuel combustion was low with the reduction of 46%in heating phase and 61% in cooking phase. Moreover,the emission levels under heating phase were more stable than cooking phase due to relatively less artificial operations. The co-fuel was cheap,whose price on a unit energy basis was 0. 039 yuan/MJ and the price on a unit mass basis was only half of coal.The burner of co-fuel was popular coal-burning stove,avoiding purchasing expensive biomass stove and ensuring the expenditure for daily energy uses within the economic bearing capacity of low-income families.