棉秆循环流化床稀相区传热系数的试验研究

在热功率0.5 MW棉秆循环流化床试验装置上对稀相区传热系数进行了测定,研究了不同参数对传热系数的影响,结果表明:环形区颗粒浓度和床温对传热系数的影响较大,且随着颗粒浓度和床温的增加而增加;一次风率和过量空气系数对不同床高的传热系数也有一定影响,传热系数随一次风率的增加而增加,但一次风率过大时,传热系数会有所下降;为了得到较高的传热系数,过量空气系数存在一个最佳值;循环倍率对传热系数的影响也很明显,在一定的范围内,传热系数随循环倍率的增加而增加;当循环倍率太大时,床温有所降低,使传热系数减小.

Experimental Studies on Heat Transfer Coefficient in Circulating Fluidized Bed of Cotton Stalk Combustion

On a pilot-scale CFB of cotton stalk combustion with the thermal input of 0.5MW,the heat transfer coefficient in the dilute zone of CFB was measured.The effects of different parameters were investigated.The concentration of particles and bed temperature have a significant effect on the heat transfer coefficient.The heat transfer coefficient goes up with the increase in the concentration of particles and bed temperature.The primary air percentage and excess air coefficient have a certain degree influence.When the primary air percentage increases,the heat transfer coefficient increases.When the primary air percentage further increases,the heat transfer coefficient slightly decreases.In addition,there is an optimum excess air for higher heat transfer coefficient.The circulation ratio has a great effect on the heat transfer coefficient and in a certain range the latter increases with the circulation ratio;however at very large ratio the coefficient will be dropped due to the bed temperature decreases.The results have provided a scientific basis for boiler design of circulating fluidized bed of cotton stalk combustion.