Abstract Slag blockages in the bottom of gasifiers cause unplanned shutdowns and huge losses for syngas utilization downstream of gasification. The sudden viscosity increase by crystal precipitation leads to slag blockage during slag tapping in entrained flow gasifiers. The temperature at which the viscosity abruptly increases is the temperature of critical viscosity (TCV), which is the strict low limit temperature for slag tapping. A comprehensive investigation of slag crystallization kinetics was performed to illustrate TCV in this work. Five slag samples with three different dominant mineral phases that commonly appear in coal ash slag were selected by thermodynamic calculations. The single hot thermocouple technique (SHTT) was applied to analyze the crystallization kinetics based on Avrami and JMA theory. The kinetic analysis indicated that anorthite showed heterogeneous nucleation and grew with a two-dimensional crystalline pattern. The temperature range for anorthite crystallization was approximately 150 °C. Corundum exhibited heterogeneous nucleation and one-dimensional growth pattern. The maximum crystal ratio was 52% for corundum at the temperature of 98 °C. Mullite showed a low E c value, resulting in a high Ton. Rapid crystallization of mullite was observed at 60 °C due to homogeneous nucleation and two-dimensional crystallization. In this work, TCV was revealed by crystallization kinetics for the first time. The relationship between TCV and the activation energy, maximum crystalline rate, and initial crystallization temperature was built to illustrate the influence of crystallization on TCV. Three equations were used for TCV prediction to guide coal selection and slag tapping in entrained flow gasifiers.

中文翻译：

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夹带流气化炉出渣条件下煤灰渣结晶动力学及TCV预测

摘要 气化炉底部堵渣会导致气化下游合成气利用的意外停机和巨大损失。在夹带流气化炉中出渣期间，晶体沉淀引起的粘度突然增加导致渣堵塞。粘度突然增加的温度是临界粘度温度（TCV），这是出渣的严格下限温度。对炉渣结晶动力学进行了全面研究，以说明这项工作中的 TCV。通过热力学计算选择了五个具有三种不同主要矿物相的矿渣样品，这些矿渣通常出现在煤灰渣中。基于Avrami和JMA理论，应用单热热电偶技术（SHTT）分析结晶动力学。动力学分析表明钙长石表现出异质成核并以二维晶型生长。钙长石结晶的温度范围约为 150 °C。刚玉表现出异质成核和一维生长模式。刚玉在 98 °C 时的最大结晶率为 52%。莫来石表现出低 E c 值，导致高吨。由于均匀成核和二维结晶，莫来石在 60 °C 下快速结晶。在这项工作中，TCV 首次被结晶动力学揭示。建立了 TCV 与活化能、最大结晶速率和初始结晶温度之间的关系，以说明结晶对 TCV 的影响。