EFFECTS OF COAL HEATING TEMPERATURE ON QUALITY, REACTIVITY AND MOISTURE RE-ADSORPTION OF LIGNITE

• Main Author: Nuril Akbarrur R., Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/82086
• Institution: Institut Teknologi Bandung

Coal is one of the main energy sources in meeting energy demands in Indonesia. Lignite coal, which its characteristics has low calorific value and high moisture content, is one of the largest coal reserves in Indonesia, but its utilization is limited because it is less efficient when burned and tends to experiencing spontaneous combustion. Therefore, it is necessary to improve the quality (upgrading) of lignite coal, one of which is by heating. This research studies the effect of heating temperature variations on the characteristics and quality, combustion reactivity, and moisture re-adsorption of lignite coal to determine the optimal temperature. In this study, lignite coal was used as raw material, which was prepared by reducing its size to a coal size range to -20 + 5 mm. Sample was splited in two part, one part acts as reference of raw coal, while another were given heating treatment in a muffle furnace at various temperatures; 60 ?, 100 ?, 150 ?, 200 ?, 300 ?, 400 ?, and 500 ? with a heating rate at 5 ?/min and a retention time for 2 hours under an inert atmosphere (1.5-liter N2/min). The raw coal and upgraded coal were then characterized by particle size distribution (PSD) analysis, proximate analysis, ultimate analysis, fourier transform infrared spectroscopy (FTIR) analysis, and calorific value test, as well as combustion reactivity test in thermogravimetricdifferential scanning calorimetry (TG-DSC) analysis, and moisture re-adsorption analysis which is done both in controlled and open environments. The experimental results show that the coal particle size distribution shifts towards finer size fractions as the heating temperature increases. The heating temperature of 150 ? is the temperature with optimal energy yield and the moisture content has decreased, yet the volatile matter content starts to decrease. Changes in the elemental content of coal are indicated by changes in the -OH functional group which is released at 200 ?, followed by the release of methyl aliphatic and -C=O functional groups at 400 ? and -C-O- group which is released at 500 ?. Combustion reactivity tests indicate that higher heating temperatures produce upgraded coal that is more difficult to be burned-out and more difficult to experiencing self-combustion. The coal upgrading process can also reduce the level of equlibrium moisture content of coal and reduce readsorption of moisture (after 72 hours) both in controlled and open environment conditions.