Characteristics of an Air-Blown Fixed-Bed Downdraft Biomass Gasifier

Abstract

An air-blown fixed-bed, stratified downdraft biomass gasifier was built to investigate the key operating parameters that affect the operational characteristics of a fixed bed. The main purposes of this investigation include studying the effects of operation parameters, such as air flow rate, air preheating temperature, air/fuel ratio, and fuel moisture content, on the fuel conversion rate, specific gasification rate, producer gas heating value, and H/C ratio, as well as cold gas efficiency and hot gas efficiency. The gasifier was designed to operate with air flow in the range between 6 and 18 Nm3 h−1. Wooden cubes (15 × 15 × 15 mm) of Red Lauan and White Lauan woods were used as fuel for the gasification experiments. The burning rate of wooden cubes was found to increase with an increasing air flow rate. The producer gas heating value showed a trend of increase with an increasing air flow rate up to 15 Nm3 h−1, and a further increase in air flow resulted in a decrease in the gas heating value, because of ...