Particulate matter properties in a bench-scale entrained-flow coal water slurry gasifler

摘要

Particulate matter (PM) of fly ash and slag is the main solid by-product of the coal gasification process which has significant influence on coal carbon conversion, slag deposition, erosion of the refractory wall and the efficiency of primary syngas cleanup. In this study, experimental work has been carried out to characterize the PM in a bench-scale opposed multi-burner (OMB) coal water slurry (CWS) gasifler. Similar to the industrial gasifier, particles in gasifler were sampled after treatment with high temperature flames. PM samples were taken from multiple ports under different operation conditions, and subsequently SEM, chemical composition and particle size tests were performed. Based on the simplified regional division of this type of gasifler, PMs in the gasifier impinging region perform porous structure and have larger particle size than that in the gasifier plug flow region. Also the unburned carbon content in PM decreases from top to bottom along the gasifier. The average particle size decreases as the oxygen carbon atomic (O/C) ratio increases. Based on the coal used for the experiments, the proposed mineral transformation mechanism also indicates that the calcite first transformed to mullite and then reacted with CaO to generate the anorthite. The investigation on the characteristics of PM will be beneficial to the operation and optimization of the OMB entrained-flow gasifier.