Buildup of high solids flux conveying flow by coupling a moving bed to the riser bottom

Abstract

Circulating fluidized bed (CFB) technology was first developed for the fluid catalytic cracking of crude oil in the 1940s, which is mainly characterized by circulating the solids between two adjacent fluidized vessels. Based on the CFB technology, dual fluidized bed gasification (DFBG) was proposed in the 1980s, but it received renewed interest in recent years as a high efficiency solids fuel gasification process for the production of high-quality syngas. In an autothermal DFBG system, heat transfer from the exothermal fluidized bed combustor to the endothermal fluidized bed pyrolyzer/gasifier, especially for pure steam gasification, relies on rapid and large solids circulation between the two vessels. A higher solids circulation rate, Gs, allows small temperature difference between the two reactors, thus making the operation and control of the DFBG system much easier. Transport bed gasification (TBG) is another newly developed thermochemical conversion method based on the CFB technology. The TBG process has the advantages of low tar evolution, modest reaction temperature, and high Correspondence concerning this article should be addressed to G. Xu at gwxu@ home.ipe.ac.cn