Abstract

The topic of appropriate technology for the conversion of waste biomass into valuable products has often been overlooked in Sub-Saharan Africa. The influence of the type of technology, biomass type, and operating parameters such as; temperature, moisture content, etc. on the conversion process, is a barely known. This contribution aimed at studying pyrolysis of wood residues, and the specific objectives were; (1) characterisation of organic products (wood vinegar and tar) of pyrolysis of wood residues, (2) investigation of the effect of temperature and feedstock type on the yield of products and (3) to carry out an energy balance of the pyrolysis reactor system. Wood residues were pyrolysed in a cylindrical batch reactor at temperatures 300-350, 400-450 and 500-5500C and the organic were characterised using a gas chromatograph (GC) fitted with a flame ionisation detector (FID). The most notable compounds in the wood vinegar and tar were; alcohols, acids, furans, phenols, aldehydes, and ketones. The yield of vinegar, tar and char reduced significantly with an increase in temperature and the maximums were produced at 300-3500C whereas the yield of non-condensable gases increased with an increase in temperature. The type of feedstock used had no significant effect on the yield and distribution of products. The energy balance of the system revealed that the process was 78% efficient. The presence of the oxygenated aliphatic and aromatic hydrocarbons makes the wood vinegar and tar potential sources of chemicals and engine fuels. Preliminary trials with wood vinegar were lethal to black ants that are predominantly a menace to farmers in Sub-Saharan Africa.

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