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

Abstract

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 700^oC 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.

Keywords: Biomass, Pyrolysis, Sample shapes, Gmelina arborea