Physico-chemical characterization study of coffee husk for feasibility assessment in fluidized bed gasification process.

Abstract

The biomasses like post-harvest agricultural residues are usually disposed of as landfills and used as cattle fodder and manure. Large quantities of such wastes are often set to open firing. The open firing of such waste biomasses leads to particulate matter emission and air pollution. Kerala, the second-largest producer of coffee in India, produces around 65,925 metric tonnes of coffee. Almost 30-50% of waste is produced during coffee processing, out of which coffee husk has a significant contribution. The thermochemical process like gasification helps in bio-energy extraction and proper disposal of coffee husk. In the present study, the physico-chemical characteristics of coffee husk are studied in detail to investigate its feasibility as a biomass feedstock for thermochemical applications. The thermal degradation of coffee husk at higher temperatures (up to 1000°C) is investigated using thermogravimetric (TG) analysis. The higher heating value is determined using a bomb calorimeter and is found to be 19.67MJ/kg. The selected sample has a volatile matter content of 66.85% and fixed carbon content of 14%. The elemental composition is also determined to identify the presence of inorganic elements in the sample. The presence of inorganic elements like potassium and sodium in the feedstock often leads to defluidization when used in fluidized bed gasifiers. The physical and chemical properties analysed would enable in apt handling and treating coffee husk prior to thermochemical processing.