Study On Drying And Separation Of The Group C Particles In A CFB System

Class C particles is a particle which size is less than20m, largerforces between particles, physical properties of active, and widely used invarious industrial production process. Developing the new deviceapplicable to class C particle drying and fluidization becomes a hot topic ofthe scientific community and industry.Circulating fluidized bed(CFB) has become a new direction offluidized research in recent years for its large concentration of particles inthe bed, easy to establish the temperature and concentration gradients,fluidifying the viscous materials, and high equipment utilization.In order to research the class C particles drying characteristics andseparation characteristics, the intermittent were carried out and continuousdrying experiment in the CFB(0.104m ID×2.35m high) reactor, regardingcorn starch, alumina, calcium carbonate(both class C particles) as objectsof study. The results show: CFB reactor can achieve the fluidization、separation and drying of selection materials, and different materials aredifferent. In the same operating conditions, batch experiment mainly studiesdrying characteristics and separation efficiency of three kinds of materialsas well as with the parameter changes situation in the CFB reactor; andresearches the particle size and air humidity on the impact of the circulatingfluidized bed drying and separation characteristics. The results show: Thedifferent combination of material and water leads to the differentcirculating fluidized bed drying and separation condition, and thedifference with the parameter changes condition; In the experimentaloperating range, the drying rate increases with the air humidity decreases orwith the particle size increases.In the same operating conditions, when achieving continuous drying,the bed temperature﹑separation effection﹑average residence time andso on change over time of three kinds of materials in the circulatingfluidized bed, and the condition with the parameter changes, particle sizeand air humidity on the impact of average residence time. The results show:When three materials achieve continuous drying in the CFB reactor, thestatus in the bed difference, under the experimental operating conditions,average residence time decreases with the air humidity decreases or withthe particle size increases.Based on the Page drying model, a mathematical model about theparticles moisture content with the height changes of riser in the CFB reactor was established. The models are as follows: Which:By verifying, the theoretical values and the experimental values match better.