Effect of Air Supply Location and Equivalence Ratio on Thermal Performance of Downdraft Gasifier Fed by Wood Sawdust

Abstract

In order to encounter the shortage of fossil fuel, many efforts have been performed by researchers worldwide to find out an alternative technologies of renewable energy conversion. Biomass gasification, one of many promising energy conversion technologies, becomes more attractive in recent years. The present work aims to investigate an effect of air tuyere-grate distance (i.e. 260, 330, 400 mm) and equivalence ratio (i.e. 0.15, 0.20, and 0.25) on thermal behavior of the small-scale downdraft gasifier fed by sawdust. The reactor has internal diameter of 300 mm and height of 725 mm (from grate to the top). The thermal behavior of the gasifier in terms of axial temperature of the reactor, volume fraction of carbon monoxide, hydrogen, methane and higher heating value of the producer gas, and also cold gas efficiency are observed and analyzed. The result indicates that tuyere position above the grate affects the performance of the gasifier. The maximum higher heating value of the producer gas and cold gas efficiency are found at optimum tuyere-grate distance of 330 mm and equivalence ratio of 2.0. The maximum higher heating value of the producer gas and cold gas efficiency are 2.84 MJ/Nm3 and 66.36%, correspondingly. 

Keywords

• biomass; downdraft gasifier; equivalence ratio; sawdust; tuyere