(378k) Quantified Investigation of Coal Ash Fusion Behavior for Gasifier Design and Operation

Coal gasification is regarded as the primary technology for clean coal utilization in large scale. Through coal gasification, chemicals and liquids can be supplied instead of only heat by coal combustion. The entrained flow gasifier is the priority choice for coal to chemicals and liquids because it is running at high temperature and pressure. In the high temperature gasification process, coal matrix transforms into syngas, but minerals go through temperature increasing and decreasing into ash and slag. Ash chemistry is proved to be more important than coal matrix at high temperature gasification. Ash fusion behavior is used as the first criteria for coal selection for gasifier. However, the traditional ash fusion temperatures used for 100 years are lack of scientific definition and of wide error range, so the application of ash fusion temperatures are more empirical. In this work, our used thermomechanical analyzer, microscopy coupled with heating stage and DSC to investigate the ash fusion behavior. The ash fusion process is divided into three stages according to the fusion rate. Deformation temperature and flow temperature is defined with physical meaning. Based on the TMA curve and thermodynamic calculation, the relation between ash composition and sintering rate is established. Meanwhile, with the help of molecular simulation, we established the new method to calculate the liquidus temperature of coal ash slag. The results could be used for gasifier operation and design.