Experimental and computational study on effect of ash deposition on fluid dynamic behavior in a bubbling fluidized bed gasifier

The effect of ash deposition on fluid dynamic behavior in a fluidized bed gasification reactor have been studied using experimental and computational methods. Experiments were performed using sand particles as bed materials and air as fluidizing agent. A 3D computational model have been developed for bubbling fluidized bed gasification reactor. First, the model was simulated using sand particles and air. The results are compared with the experimental results. The comparisons show good agreements between the two sets of the results. The model was further used to study the effect of ash accumulation on the fluid dynamic properties of a biomass gasification reactor. The bed materials were mixed with 2 and 4 volume percent of ash and simulated in cold conations. Pressure drop increases and minimum fluidization velocity decreases with increasing the ash deposition in the bed. The model was also simulated for 2, 4 and 6 volume percent of ash at a temperature of 800ºC. The minimum fluidization velocity is further decreased in all cases. The particle species concentration show the ash particles start to segregate at the minimum fluidization condition and totally segregated at higher velocities. The bubble behavior of the bed is not effected by ash deposition.