Experimental studies on mixing characteristics and criterion of cotton stalk combustion in fluidized bed

The mixing characteristics of binary mixture of cotton stalk with 10-100 mm length and alternative bed material in a fluidized bed were studied. Experiments on a cold test facility show that long cotton stalk cannot fluidize, and adding bed material can improve the fluidization condition. Effects of length and mass percentage of cotton stalk, diameter of bed material and gas velocity on cotton stalk mixing were investigated. Long cotton stalk can mix well with 0.6-1 mm alternative bed material as fluidization number ranging between 3-7. The minimum fluidizing velocity of the binary mixture of long cotton stalk and 0.6-1 mm bed material can be obtained by experiments. In addition, the mixing criterion for binary mixture of long cotton stalk and bed material in experimental conditions is presented. When the degree of mixing is less than 1.4, the mixing state of long cotton stalk and bed material can mix well and adapt to fluidized bed combustion.