Characteristics of Tar Thermal Cracking and Catalytic Conversion during Circulating Fluidized Bed Char Gasification

Abstract

Thermal cracking and char catalytic conversion of tar were carried out on a laboratory-scale circulating fluidized bed to provide theoretical support for the removal of tar. The used char and gas were characterized using a portable infrared analyzer, a specific surface area analyzer, proximate analysis, etc. Catalytic conversion of tar was more effective than thermal cracking. It could inhibit carbon deposition and improve the quality of syngas. The effect of temperature and tar amount on the catalytic conversion of tar during circulating fluidized-bed char gasification was investigated. The effect of temperature on the catalytic conversion of tar was remarkable. The efficiency of tar conversion (ETC) increased significantly with increasing temperature. A tendency for catalytic conversion of tar at different temperatures was revealed. As the amount of tar feeding increased, the ETC would decrease because of the carbon deposition. In this process, a maximum increase of low heating value (LHV) was discovered and so there was an optimum amount of tar treatment for a certain amount of char.