EFFECT OF FLUIDIZATION RATIO ON THE PERFORMANCE OF AN INTERNALLY CIRCULATING AERATED FLUIDIZED BED GASIFIER WITH CONCENTRIC CYLINDERS

Effects of fluidization ratio (RQ) on the bed temperature, composition and heating value (HV) of producer gas (PG) during gasification of sawdust in an internally circulating aerated fluidized bed gasifier (ICAFBG) based on the indirect heating principle with concentric cylinders were studied. RQ which is the ratio of aeration rate in annulus (Qan) to the fluidization rate in the draft tube (Qdt) strongly affect the ICAFBG performance as it is a driving force to transport the char from gasification to the combustion zones. The char combustion in the combustor (draft tube) is the heat provider to the gasification process in the gasification zone (annulus). The results showed that by increasing RQ resulting in increased bed material temperature, PG composition and HV. However, increase RQ further caused temperature reduction as well as PG composition and HV. The HV could be increased from 4.52 to 6.98 MJ/m3 in the RQ ranges from 0.14 to 0.43. However, by increasing RQ further to 0.57 caused reduction in HV to 5.61 MJ/m3. The highest bed temperature which can be achieved was 806 oC at 0.43of RQ.