Investigation of the swelling pressure development during slow pyrolysis of thermoplastic coals

Both, the high and low swelling pressure coals, were thermally investigated using series of gas analysis and long distance microscopic techniques. Results showed similarities in the amount of gas release between the two coals, especially for lower molecular weight volatiles; however, the prime difference was in their tar evolution rates and temperatures. For this purpose, the tars were collected for both coals and their blends and further analysed using matrix assisted laser desorption ionisation mass spectrometry (MALDI). Furthermore, a long distance microscopic analysis was performed on single particles under pyrolytic heating conditions revealing significant differences in the transient structural changes between both coals, which were caused by viscosity of the plastic phase and their consequent tar content.