利用循环流化床锅炉烟气余热干燥废木材方案比较

Methods comparison of drying waste wood by waste heat from flue gas of circulating fluidized bed boiler

为解决浙江某生物质电厂75 t/h循环流化床生物质直燃锅炉运行中存在的排烟温度高达180~190℃带来的效率降低,以及燃料废木材含水率超过45%会导致锅炉熄火的问题,提出利用锅炉尾部烟气余热加热空气、水等不同介质将排烟温度降低至150℃以下,同时利用加热后的介质间接干燥废木材,从而将废木材含水率降低5%左右,达到锅炉对燃料含水率的适应范围要求。同时,通过对不同介质加热废木材的能量平衡和质量平衡计算以及经济性分析,认为利用循环流化床锅炉烟气余热干燥废木材的最佳干燥方式为空气预热器加干燥机方案。

In order to solve the problem of the low efficiency brought by the exhaust gas temperature up to 180~190℃of a 75 t/h biomass circulating fluidized bed boiler in a biomass power plant in Zhejiang and the boiler flameout brought by the water content of the waste wood higher than 45%,this study presents that,the exhaust gas temperature is reduced to below 150℃by using the boiler waste heat to heat air,water and other different media.And the waste wood moisture content is decreased to 5%by using the heated medium to dry wood waste indirectly to meet the water content requirements of fuel for the boiler.Meanwhile,the energy balance,mass balance and economic efficiency of heating waste wood by different media are calculated.The results show that the method of air preheater plus dryer is considered to be the best drying method of dry waste wood by the waste heat from flue gas of circulating fluidized bed boiler.