Experimental Investigation of the Effect of Sample Shape on Biomass Pyrolysis Characteristics in a Fixed Bed Reactor

In this research work, the product yield distribution from four different sample shapes of a biomass feedstock (Gmelina arborea) was investigated. The biomass feedstock (Gmelina arborea) was procured from Pakiotan Sawmill in Ogbomoso, South-Western Nigeria. The biomass feedstock was machined into four different shapes (rectangular, cylindrical, disc and equant) of equal volume of 22.8 cm3 on the wood Lathe machine at the Engineering Workshop of Ladoke Akintola University of Technology (LAUTECH), Ogbomoso, Nigeria. Experiments were carried out at four different temperatures (400, 500, 600 and 700 oC) at a residence time of fifteen minutes and at a constant vacuum pressure using a fixed-bed reactor. Results obtained showed that tar yield was 3.66 % at 700 oC and 18.15 % at 400 oC for cylindrical shape, and 7.5 % at 700oC and 25.04 % at 400 oC for disc shape. From the experimental data, it was also observed that the cylindrical shape has the highest gas yield of 80.11 % at a temperature of 700 oC while the disc shape has the lowest gas yield of 49.74 % at 400 oC. Result also showed that, the rectangular shape has the highest char yield of 27.25 % at 400 oC while the cylindrical shape gave the lowest char yield of 16.23 % at 700 oC. This study established that, pyrolysis of the same feedstock with different sample shapes under the same pyrolysis conditions produced different product yield distribution. Also, sample configuration affects various intra-particle physical phenomena involved during pyrolysis