Assessing the Potential of Coffee Parchment for its Effective Utilization as Alternative Biomass Fuel in Cement Industry

Abstract

Many of the developing countries produce huge quantities of agro-processing residues with an interesting potential for biomass energy production provided that the higher moisture content and lower density of the biomass is managed to improve the combustion and handling problems. But they were used inefficiently causing extensive pollution to the environment. Moreover, the methods for effective utilization of the wasted resources specifically coffee parchment were not well developed. Therefore, this study were carried out to investigate potential of wasted resource, specifically coffee parchment to produce energy either alternatively used or supplement the current energy demand of cement industry. This was investigated by: estimating quantity of coffee parchment generated from different wet coffee processing facility, establishing optimum route for collection, and, characterizing the quality and type of raw biomass fuel and upgrading the fuel so as to enhance transportation, handling and utilization with optimum efficiency of kiln and without degrading the quality of clinker produced. Related to this distance between wastes sources were identified according to their position identified using GPS and finally with the help of the Arc-GIS software to choose optimized collection routes; different instruments and ASTM standard procedures were used for chemical, proximate and ultimate analysis of raw coffee parchment and pellet. Moreover, heating value, Ash oxide analyses and trace metal analysis were examined in order to investigate combustion properties and quality of the product to be used in clinker production and the results were compared. The analysis result showed the quantity of coffee parchment generated were estimated to be in the range of 10,583.5 to 12,460.5 tonnes per year, however it has been used inefficiently and irregularly by the local population who utilize the loose parchment as a cooking fuel. It was found within a radius that covers a total distance of 41.6 km. Ultimate analysis result confirmed higher C (45.5%) and H(6.5%) and lower N (0.4%) and S (0.1%) contents in the coffee pellet as compared to most commonly used biomass fuel and meet the standards specified for non-wood pellets, which implies that it has suitable property for alternative fuel use. Moreover, moisture content (11.2%) and ash content(5.97%) of the pellet is less than the amount specified in most biomass fuel and in accordance with ISO 17225-6 standard for non-wood pellets sated to use as alternative fuel and meets requirements of cement industry for thermal utilization. The observed lower fixed carbon contents (8.6%) in the coffee parchment pellet than many other woody and non-woody biomass might be related to differences in the chemical composition of the used biomass as well as the operations conditions. Improved gross heating value (HHV) from 18.56 and 27.95 MJ/kg and Ash oxides contents as a result of pelletizing of coffee parchment makes coffee parchment to have comparable values to common fuel woods and coal. This makes coffee parchment pellet suitable to be used as alternative energy source to be used in the clinker sintering zone for proper kiln operation and satisfactory quality of the clinker product up on careful design of the fuels ash and the raw materials. Overall analysis result confirmed that laboratory prepared coffee parchment pellet can be a promising source of alternative fuel and its effective utilization may reduce the raw material demand in cement industry in addition to its contribution to supplement fuel demand which rely on imported coal.