Briquetting lignite-biomass blends to obtain composite solid fuels for combustion purposes

Abstract

The main aim of this study was to determine the possibility of briquetting lignite-biomass blends to obtain composite solid fuels (CSF) for combustion purposes. Research was conducted at Department of Manufacturing Systems and Department of Thermal Engineering and Environmental Protection, AGH University of Science and Technology to develop a technology for briquettes preparation. The briquetting process was carried out in the cylindrical die and in the roll press. The gravity hopper and new asymmetrical layout briquetting system were used in the roll press and briquettes in the shape of the saddle i.e. without the splitting plane were obtained. Effects of the ratio of biomass to lignite (20/80; 30/70;40/60 and 50/50), moisture content (9.9%-31.3%), and briquetting unit pressure (32-210MPa) on the strength of the briquettes were investigated. The obtained results showed possibility of briquetting of lignite-biomass blends in the cylindrical die and in the roll presses and the mechanical strength obtained briquettes was high i.e. shatter index >90% and compressive strength >1MPa. All of the produced briquettes were not water resistant. Based on physical and chemical analysis of prepared briquettes it was confirmed that briquettes have good fuel properties for combustion process. Thermal behavior of studied lignite and prepared mixture was investigated by thermogravimetric analysis (TG). The samples were placed in an alumina crucible. C.a. 15 mg of sample was heated from an ambient temperature up to 1000°C at constant two rates: 10°C/min and 40°C/min in a 40 ml/min flow of air. Finally, basic analysis of ash from burning briquettes were carried out and some of the results are presented.