Investigation of the maceral composition of coals with different ranks and of the char morphology during high temperature and high pressure entrained flow gasification

Entrained flow gasification represents a promising technology for low emissions power generation. A good understanding of the behaviour of solid fuels under entrained flow gasification conditions is important to the development of feedstock-specific gasifier models, and the importance of char structure to this understanding is well documented. The maceral composition of the coal and the reaction conditions have been shown to significantly influence the structures and morphologies of chars generated from devolatilization. There remain few studies, however, that provide insights into the formation of different char types under conditions similar to industrial gasifiers. In this work, the maceral compositions of an anthracite, bituminous coals, and a lignite are investigated using a reflected-light based optical imaging system, the Coal Characterisation Imaging System (CCIS) developed at CSIRO. The use of this with the Coal Grain Analysis (CGA) technique allows for semi-automated characterization of the maceral composition of many individual coal grains. These results can be related to chars formed from gasification experiments in the Pressurized High Temperature Entrained Flow Reactor (PiTER) at the Institue for Energy Systems of the Technical University of Munich at temperatures up to 1600°C and pressures up to 2.0 MPa. The CGA technique was combined with a semi-automated analysis of char morphology to determine char morphological types. This work gives some insights into the links between coal petrography, gasification conditions and char structure. The results confirm the strong relationship between the coal petrography and char morphology, and show the effect of gasification conditions on the char structure.