Effect of Air Velocity, Type and Size of Biomass on Performance of Downdraft Gasifier

Abstract

Investigation on thermal gasification of different biomass materials viz., Pigeon pea stalk (Cajanus cajan),Cotton stalk (Gossypium hirsutum) and Vilaytee babool (Prosopis juliflora) in a downdraft gasifier (1 Kw capacity) was conducted to study the effect of air velocity, type and particle size of biomass. The influenceof three different particle sizes viz. 25-50, 50-75, 75-100 mm, at three different air velocities viz., 2.4, 7.4 and12.4 m s-1 on biomass consumption rate, gas flow rate and gasification yield was investigated. With theincrease in particle size, the reduction in biomass consumption rate was observed, whereas the increase inair velocity increased the biomass consumption rate. Similar trend was observed in gas flow rate andgasification yield respectively. Under the experiment conditions, the biomass consumption rate, gas flowrate and gasification yield of selected biomass material varied in the range of 3.80 to 7.76 kg h-1, 6.13 to 14.40Nm3 h-1 and 1.40 to 2.30 Nm3 kg-1, respectively. The experimental results showed that the gasificationperformance was better for Vilaytee babool (Prosopis juliflora) biomass with 25-50 mm size at 7.4 m s-1 airvelocity.