火电行业的降碳工作直接关系到"双碳"目标的实现,而循环流化床炉具有燃料适用性广的优势,能够大比例掺烧可再生"零碳"能源-生物质燃料,大幅降低火电厂碳排放.在役循环流化床炉和燃煤条件,进行生物质混合掺烧试验,并对燃烧稳定性、污染物排放及热效率进行了综合评估.掺烧试验结果表明:生产单位蒸汽煤耗量随掺烧比增大显著降低,燃烧工况稳定;掺烧条件下单位石灰石耗量降至 4.5 kg/t蒸汽左右,SO2 排放量达标;掺烧后炉内温度升高,排烟温度升高,而飞灰量增大,使热损失有所增大;通过调控风量配比、料层差压及过量空气系数,总体热效率接近设计值;长期运行条件下,生物质掺烧比达到约30%,SO2和NOx排放量合格,尾部受热面未受明显腐蚀,1 t蒸汽减排CO2 量约 480 kg.
Study on carbon emission reduction via co-firing biomass in circulating fluidized bed boilers
Decarbonization in thermal power industry is directly related to the realization of the"double carbon"target,while the circulating fluidized bed boiler has the advantages of wide fuel applicability and can carry out large-scale fuel blending.Biomass fuel is a renewable"zero-carbon"energy source,its blending can greatly reduce the carbon emissions of thermal power plants.Based on the existing circulating fluidized bed boilers and coal-fired conditions,biomass co-firing tests were conducted,and comprehensively evaluation was also carried out on combustion stability,pollutant emissions,and thermal efficiency.The co-firing experiments results showed that,as the co-firing ratio increased,the coal consumption rate per unit of steam production significantly decreased,with stable combustion conditions maintained throughout the process.Under co-firing conditions,the consumption of limestone decreased to approximately 4.5 kg for 1 ton steam production,with SO2 emissions meeting the standards.Blending raised the furnace temperature,elevated the exhaust temperature,increased the fly ash content,and slightly increased the heat loss.Through regulating the air volume ratio,material layer pressure difference and excess air coefficient,the overall thermal efficiency closely approached the design value.Under long-term operating conditions,the blending ratio of biomass reached about 30%,and the emissions of SO2 and NOx were qualified.The tail heat exchanger was not corroded obviously,and the CO2 emission reduction amount reached about 480 kg for 1 ton steam production.
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