Abstract: Experimental studies were carried out in a specially designed high-density “riser-downer-riser” coupled circulating fluidized bed system. Fluidized catalytic cracking (FCC) particles were used.Compared with the primary air rate, the secondary air rate had an important effect on the solids circulation flux. When the solids circulation flux was 400 kg•m^-2•s^-1, the apparent solids holdup exceeded 20% near the top of the first riser, and the volumetric solids fraction (apparent solids holdup) was larger than 5.5% in the fully developed region of the downer.With increasing solids circulation flux, more uniform solids concentration distribution along radial direction could be obtained.

摘要： 在新提出并建立的“下行床-提升管”耦合循环流化床装置上进行了实验研究，研究结果表明，与提高一次风率相比，提高二次风率（二次风与一、二次风之和的比值），有利于提高颗粒循环量.当颗粒循环量达到400 kg•m^-2•s^-1时，第一提升管出口处的固含超过了20％，此时下行床内充分发展段的固含超过了5.5％，即高浓度颗粒充满了整个循环流化床系统，并且第一提升管内的颗粒径向浓度分布趋于均匀.