On the basis of boiler exergy balance mathematical model,the exergy efficiency and each exergy loss of large-scale circulating fluidized bed (CFB)boilers was analyzed.The results show that,the total ex-ergy loss of combustion and heat transfer of the CFB boiler was over 45% of the fuel chemical exergy, which is the main exergy loss of the CFB boiler.Increasing the power unit capacity and steam parameters can increase the average heat absorption temperature of the water in furnace,thus to reduce the heat trans-fer exergy loss of the boiler effectively.The exhaust exergy loss rate was about 1%,which is greatly smal-ler than that of the exhaust heat loss rate,but there's still potential to be tapped.For CFB boilers,the exer-gy loss rate during combustible gas incomplete combustion and heat transfer can be ignored.The unburned carbon exergy loss,which is the chemical exergy of the unburned carbon,should be paid more attention to be reduced due to its high quality.The CFB boiler slag has a high proportion of coal ash,so reducing the slag physical exergy loss has great significance to improving the CFB boiler efficiency.%采用锅炉火用平衡数学模型，对大型循环流化床(CFB)锅炉的各项火用损失和火用效率进行了分析，并以某亚临界300 MW机组CFB锅炉为对象，进行了实例计算，并对不同参数等级CFB锅炉进行了火用效率分析。结果表明：CFB锅炉的燃烧和传热火用损失之和占燃料化学火用的45％以上，是锅炉的主要火用损失；提高机组容量和蒸汽参数，可以提高炉水平吸热温度，从而有效降低锅炉传热火用损失；锅炉排烟火用损失率在1％左右，比排烟热损失率小很多；CFB锅炉的可燃气体未完全燃烧火用损失率、散热火用损失率均可忽略不计；固体未完全燃烧火用损失由于损失的是未燃尽碳的化学火用，其热能品位较高，因此应重点采取措施减小该项损失；CFB锅炉炉渣占煤中灰分比例较高，降低炉渣物理火用损失对于提高锅炉效率具有重要意义。
展开▼
