Effect of tuyer distance above grate on propagation front and performance of downdraft gasifier with the feedstock of rice husk

Although several works on rice husk gasification have been reported, none of those works investigated and discussed the propagation front. In present work, rice husk gasification is conducted in a small-scale throat-less downdraft gasifier. The aim of the work is to investigate the effect of tuyer distance above the grate on the propagation front and performance of the gasifier. Rice husk gasification is performed at an equivalence ratio of 0.20 with variations in tuyer position above the grate of 120 mm, 190 mm, 260 mm, 330 mm, and 400 mm. The result shows that tuyer distance above the grate affects the propagation rate and the performance of the gasifier. The flame and bed propagation rates are nearly similar for the tuyer 400 mm above the grate. Meanwhile, a volume fraction of combustible gases CO, H2, and CH4 improve as tuyer distance above the grate increases. Maximum values of 15.18% CO, 6.99% H2, and 0.99% CH4 are obtained for the tuyer 400 mm above the grate. Maximum HHV of 3.21 MJ/Nm3 and thermal efficiency of 76.90% are also achieved for the tuyer 400 mm above the grate.