Operation Characteristics in a Fluidized Bed Gasifier with Triple-beds and Dual Circulation

Abstract

A new type of circulating fluidized bed gasifier was proposed. The main features of this proposed gasifier are the adoption of a triple-beds structure (comprising pyrolyzer, gasifier, and combustor), the separation of a circulation path for tar-absorbing material and that for the fuel and silica sand. Independent circulation systems are employed for the fuel system and for the tar-absorbing particles, and the pyrolyzer and gasifier each have a two-stage fluidized bed: the lower stage is for the fuel system and the upper stage is for the tar-absorbing system. The two circulation systems each have an independent combustor. This new gasifier is called “a fluidized bed gasifier with triple-beds and dual circulation”. The objectives of this work are to clarify the operation characteristics by using a laboratory-scale cold model. As a result, the stable circulation of the particle in upper and lower stages was able to be verified. Additionally, a wide range of the particle circulation rate, which contains the target value, was obtained. The particle circulation rate can be arranged by pressure drop of riser.