Abstract
A new type of circulating fluidized bed gasifier, which is called a fluidized bed gasifier with triple-beds and dual circulation, was proposed. Main features are the adoption of a triple-beds structure, the separation of circulation paths for tar-absorbing particle and fuel. Pyrolyzer and gasifier each have a two-stage fluidized bed. Tar can be treated in the gasifier. The two circulation systems each have an independent combustor. In this study, the fundamental gasification experiments were carried out using a small twostage fluidized bed gasifier. The amount of H2 formed during pyrolysis was markedly increased by tar cracking on porous alumina. Additionally, under steam gasification condition, H2 was also produced by steam reforming of coke. The heat balance calculations were carried out based on data of fundamental gasification experiments. The cold gas efficiency of our proposed gasifier is about 7% higher than that of typical dual fluidized bed gasifier. The particle circulation experiments were carried out by using a labolatoryscale cold model circulating fluidized beds. The particle circulation rate required for thermal independence operation was acquired. The gasification performance by bed material was evaluated. There is no big difference in the gas yields of porous alumina and limestone.
