Abstract

                                Tar reduction is a major technical challenge which needs to be addressed in biomass gasifier systems. This study presents an experimental evaluation of dual air supply downdraft gasifier with respect to better producer gas quality in terms of reduced tar and particulate content. Experiments were conducted by varying the secondary air flow from 15 to 30 % at constant equivalence ratio of 0.4. The secondary air flow was optimized at 25 % with tar content of 241 mg Nm^-3 and lower calorific value of 4.51 MJ Nm^-3. The dual air supply in the gasifier allowed a reduction of 79 % tar content as a result of partial oxidation of volatile compounds in the pyrolysis zone.

Key words : Downdraft gasifier, Dual air supply, Producer gas, Tar, Particulate