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.

Effect of Steam on the Tar Reforming during Circulating Fluidized Bed Char Gasification

“…Detailed descriptions could be found in our other work. 33 The gasifier is a stainless steel cylindrical tube with an inner diameter of 130 mm and a height of 1000 mm. The wall thickness is 10 mm.…”

“…The char was fed in the bottom of the riser by the screw feeder and reacted with the gasification agent fed by the wind caps; the high-temperature gas was discharged from the outlet of the cyclone separator and then entered the gas cooler, fabric filter, and other purification devices. Detailed descriptions could be found in our other work . The gasifier is a stainless steel cylindrical tube with an inner diameter of 130 mm and a height of 1000 mm.…”

Commissioning Analysis and Improvement measures for Biomass Circulating Fluidized Bed Gasifier

“…Tar is inevitable during biomass gasification. With the increase of gasification temperature, tar production in gasification gas decreases rapidly [10]. Therefore, on the one hand, the negative pressure operation of gasifier should be controlled to prevent the reverse channeling of biomass combustible gas.…”