【摘要】 通过建立气相法聚乙烯冷凝模式操作流化床乳化相中粒子外边界层的热质传递模型 ,研究了冷凝模式操作时聚合粒子的过热情况 .模拟结果显示在通常条件下 ,聚合物粒子在生长初期的表面温度存在多重稳态解 ;冷凝操作有助于降低大的聚合物粒子的边界层温度梯度 ,但对粒子生长初期的边界层温升几乎没有影响 ;慢启动、高活性、快衰减的催化剂最适合于冷凝模式操作更多还原

【Abstract】 A heat and mass transfer model across the external boundary layer of polymer particles in emulsion phase with condensed mode operation was derived.The overheat possibility of particles was analyzed by using the model.Simulation results indicate that in the early lifetime,there exist multi-steady states of surface temperature of growing particles.Using the condensed mode operation will be helpful to reduce the temperature gradient for larger particles,but not for very small particles.The type of catalysts with a low startup,high activity and quick deactivation was suggested to be used in the condensed mode operations.更多还原