Cold Experimental Study On Loop Seals Of Circulating Fluidized Bed

Loop seal is one of the key components of a circulating fluidized bed (CFB). Its operation properties have important influence on the CFB’s safety and steadiness. Several problems emerge with the capacity of CFB boilers increasing. In order to solve these problems, a series of experiments were conducted on a cold circulating fluidized bed test rig. The diameter of the riser is0.1m and the height is3m. The influence of structure and operation parameters on the experimental system with new style loop seals was investigated.The system’s operation characteristics were compared between one-staged and two-staged loop seals. The experimental results show that when two-staged loop seals are adopted, the location of the pressure balance opening has no influence on the solids circulating rate and the pressure balance of the entire system. The relative errors were all under26%through comparing calculated distance between loop seals and the measured bed height in standpipe. When different loop seal was adopted, the solids circulating rate demonstrates similar trend and the pressure drop in the standpipes were nearly equal. The pressure fluctuation was higher when one-staged loop seal was applied, which indicates the CFB with two-staged loop seals was more stable relative to one-staged loop seal.The solids circulating rate and the stagnation zone of an inclined-bottom loop seal were also studied. The experimental results show that the solids circulating rate increased with the fluidizing velocity, inventory and aeration rate of loop seal increasing. The increase would be more apparent with the inclined angle getting larger. The stagnation zone became smaller as the fluidization velocity, inventory and aeration rate of loop seal increased. Compared with the normal loop seal, the loop seal with appropriate inclined angle not only have the same solids circulating rate but also have smaller stagnation zone. The structure of loop seal would be simplified as a result the total cost and the complexity of the system would both be reduced.