Experimental Study of a Biomass Downdraft Gasifier with Multi-tube Gas Outlets to Improve Synthesis Gases Quality

摘要

A downdraft gasifier is favored due to its easy fabrication and due to low tar content in the synthesis gas.This work presents a designed and experimental results of downdraft gasifier.The throat,the smallest cross-sectional area,is approximately 175 millimeters.The gasifier is divided into 2 pieces(top and bottom)for easy fabrication and cleaning of the internal parts.The top is a fuel chamber while the bottom is a reaction and ash chamber.This gasifier was made of carbon steel inserting multi-tube(12)carbon steel of 1 inch diameter to be outlets of synthesis gas.These tubes were returned back to drying and pyrolysis zones of the top chamber as a heat source to wood pellets.The gasification was carried out under atmospheric pressure with ambient air as gasifying agent.Experimental results showed that average volumetric percentage in the synthesis gas were 39.71 % CO,16.48 % CO2,36.26 % H2 and 7.55 % CH4,.The gasification efficiency of this work of 40.47 % can be achieved.