A comparison of the energy and product distribution from biomass gasifiers

A detailed analyses of the raw producer gas streams generated by a downdraft gasifier and by a fluidized‐bed gasifier are presented and are discussed in terms of raw gas clean‐up considerations and of energy conversion efficiency. The major gasifier operating parameters such as fuel/air ratio, carbon conversion efficiency, net energy conversion efficiency, and producer gas heating value are then compared between seven operational gasifiers and a computer simulation model of a fluidized‐bed gasifier developed by Queen's University. It is concluded that the Queen's University model correctly predicts that the fuel/air ratio is the single most important parameter for determining gasifier performance. Downdraft gasifiers exhibit superior energy conversion efficiency and producer gas quality because they utilize a higher fuel/air ratio than do fluidized bed gasifiers.