Study on the fluidity of ash slag of liquefaction solid product and lignite co‐gasification

Abstract

The utilization of liquefaction solid product (LSP) obtained from fluidization reaction pyrolysis has become a pressing obstacle limiting the industrialization of coal liquefaction technology. In this work, gasification of LSP and Hami lignite coal (LC) and their blend at different ratios was investigated. In addition, the melt flow, mineral transformation, and crystallization behavior in the fusion process and cooling process were investigated. The results show that both LSP and LC are typical crystalline slags and cannot be applied to entrained flow gasification alone. The co-gasification of LC and LSP is a feasible method to improve their fluidity. At the ratio of 2:1 (LC to LSP), the blend has the lowest AFT. For molten slag, viscosity of the sample corresponded well to the structure of the slag. LC1:2LSP with higher Q 2 and Q 3 content showed a high viscosity, while LC1:2LSP with higher Q 0 and Q 1 content showed a lower viscosity. Besides, the size of the crystals generated during cooling is inversely proportional to the high-temperature viscosity of the sample, the migration of ions became difficult, and the growth of crystal size was inhibited at high viscosity. Meanwhile, the slag type of samples was influenced by the precipitated crystals. T cv can be effectively reduced by blending LC with LSP in a certain proportion. The results provide a theoretical basis for the utilization of LSP for the operation of entrained flow gasification.

Performance of minerals and crystallization properties of synthetic slags with various CaO/MgO in slagging gasifiers

“…Besides the chemical composition of coal ash, the crystallization behavior of high-temperature molten slag is also an important factor, leading the complex and variable fluidity of slag. 19,20 Crystal precipitation inside the liquid slag layer will affect the liquid-solid ratio of the liquid slag, causing the transformation of the slag from Newtonian fluid to non-Newtonian fluid. 21 There are different precipitation temperatures for different crystals and they are usually affected by the chemical compositions of molten slag.…”