Viscosity-temperature property of coal ash slag at the condition of entrained flow gasification: A review
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Abstract
Viscosity-temperature property of coal ash slag plays the key role for stable and long term operation of entrained flow gasifiers, which is the quantitative parameter for slag tapping process. It is described by a curve of slag viscosity as a function of temperature, which includes three aspects: viscosity value dependence on temperature, temperature of critical viscosity (TCV), and pattern of slag viscosity-temperature curve. A clear and comprehensive understanding of viscosity-temperature property of coal ash slag and its influencing factors is really important for slag tapping, operation and design of a gasifier. This review begins with essence of slag viscosity-temperature property and requirement for slag tapping, and then focused on utilization of basic oxides to adjust slag viscosity-temperature property. It was found that TCV of a crystalline slag is vitally dependent on crystallization behavior of slag, and crystallization kinetics of slag needs further to be investigated in the future. In addition, residual char in slag, water vapor in syngas, and temperature program in viscosity measurement significantly affect the slag viscosity-temperature property and slag tapping process. Finally, based on results reported in the literatures, several perspectives were proposed for future studies on slag viscosity-temperature property of coal ash slag.