A Comparative Study of the Gasification of Solid Refuse Fuel in Downdraft Fixed Bed and Bubbling Fluidized Bed Reactors

Abstract

A comparative experimental study was conducted for fluff-type solid refuse fuel which was known to be difficult to apply thermal process, using two lab-scale gasifiers; downdraft fixed bed and bubbling fluidized bed reactors, to find out the best available option for gasification of this type of fuel. The experiments were carried out at 900 °C, by changing the air equivalent ratios ranged from 0.2 to 0.6, and analyzing the syngas composition, yield, and contents of C2–C6 related with tar content. The results showed that the gasification performance in terms of syngas yield, heating value of syngas, cold gas efficiency, carbon conversion efficiency, and tar content was generally better in the bubbling fluidized bed reactor than the downdraft fixed bed reactor. The best results were obtained at 0.4 of air equivalent ratio in a bubbling fluidized reactor, with producing the highest quality of syngas, having syngas composition with 72.53% of H2 + CO and 0.483% of C2–C6, and showing 14.43 MJ/Nm3 of lower heating value. At this condition, 0.74 m3/kg of gas yield rate, 67.31% of cold gas efficiency, and 63.70% of carbon conversion efficiency were obtained. With the results from this study, the gasification process with bubbling fluidized bed reactor could be suggested that it was more suitable for better efficient application to solid refuse fuel with more stable operation.