Production of charcoal briquette to be used as cooking fuel by pyrolysis of non-woody biomass and recovery of smoke for vinegar production

Abstract

The depleting oil reserves impose a threat to ever-increasing energy requirements all over the world. This necessitates research and development on alternative energy sources such as energy from biomass. The main concern of this research work was production of charcoal briquette from non woody biomass such as coffee husk, saw dust and Chat Geraba using pyrolysis process and recovery of pyrolysis co-product (smoke) for vinegar production. The charcoal briquette was produced from the char with the help binder using PVC molding tools. It has greater advantage for recovery of clean renewable energy sources and reduction of deforestation of indigenous trees. The raw material i.e. particular biomass used as raw material should be characterized i.e. its fixed carbon content, volatile mater, moisture content and ash content should be known since these components have an impact on the calorific value of final briquette. Then the characterized biomass (coffee husk, saw dust and chat Geraba) is pyrolysed using carbonizing kiln to produce char which is used as raw material for production of briquette. The optimum temperature and heating time of the carbonizer are found to be 5000C and 3 hours respectively. The char is then grinded into appropriate particle size using grinding machine to have uniform particle size which helps to have good quality charcoal briquette. This char is then mixed with appropriate binders (molasses, starch and clay) with standardized mixing ratio and briquetted using manual operated hand press briquetting technique. Finally, the briquette has been characterized in terms of its calorific value, volatile matter, moisture content, ash content and fixed carbon content and it has the values of 24.098 MJ/kg, 20%, 7.6%, 7.4% and 65% respectively. These are the characteristics of charcoal briquette produced from Chat Geraba (which is best raw material out of the others) with molasses which is the best binder from others. Each kilogram of charcoal briquette (the product) can substitute 1.72 kg of wood and it can protect 2.97 kg of CO2 from emission to the environment. The other product of slow pyrolysis is wood vinegar which is produced by condensation of synthesis gas or smoke emitted during pyrolysis of coffee husk, saw dust and Chat Geraba by using condensation technology. The liquid condensate is separated to its component (Bio oil, wood vinegar and coal tar) using sedimentation or centrifugation process. Wood vinegar is used as pesticide, fungicide, insecticide and herbicide while the bio oil can be upgraded to transport fuel but the economic feasibility need to be assessed. The Coal tar is used as a binder for briquetting process. The wood vinegar produced has the characteristics of specific gravity 1.020 and pH = 3.857 which has acidic characteristics.