Operating Characteristics of a Tar Reformer in a New Fluidized Bed Gasification System

Abstract

Gasification is a key technology for efficiently utilizing solid fuels. The large moisture content in lignite can be utilized during gasification reactions. Since a fluidized bed gasifier usually operates at low temperature, highly concentrated tar is generated with syngas. It is important to design a system that can decrease tar. In this study, a new fluidized bed gasification system that use a tar reformer, which consists of a dual fluidized bed, was proposed. A tar reformer that contains tar-absorbing particles in the stage subsequent to the fluidized bed gasifier was employed. This allows for the re-utilization of tar-absorbing particles for extended periods of time by separating the tar-absorber and tar-absorber regenerator. The purpose of this study was to predict the behavior of the tar-absorbing particles in the tar reformer using a laboratory-scale cold model tar reformer. Additionally, the gasification characteristics of lignite were evaluated using a laboratory-scale hot model fluidized bed gasifier. As results, the behavior of particles in the tar reformer and the gasification characteristics of lignite were investigated by using a laboratory-scale fluidized bed. The calculated pressure profile in the tar reformer corresponds qualitatively to the measured pressure profile. Additionally, for the gasification characteristics of lignite, the gas yields in syngas were increased remarkably by the effect of steam, while the tar concentration in syngas decreased significantly.