循环流化床底部密相区固体混合特性的研究

It is recognized that the flow structure in the riser of a circulating fluidized bed (CFB) can be described by a dense bottom zone, a splash zone, an upper dilute zone and an exit zone. Though the bottom zone occupies only a small height, it is of particular importance because of many reasons: it is located at the uppermost stream of the riser, there exists high solids holdup, the dispersion of the fuel is directly related to the hydrodynamics in the bottom zone, etc. The purpose of the present work was to study the hydrodynamics, heat transfer and solids mixing in the bottom zone. In doing this, hot particles tracing technique, visualization techniques, miniture heat transfer probe and magnetic separation technique were employed.

循环流化床的大型化发展趋势必然面临着床内固体颗粒不能迅速混合均匀的难题。本项目的主要内容是目前尚属研究空白的循环流化床底部密相区内的圆体混合特性，实验中将采用磁性分离技术，实现既能连续稳态操作，又能较精确地测量出示踪颗粒浓度，从而可获得丰富的实验数据；同时还将进一步研究底部区内固体混合的机理，并建立相应的三维机理模型。