气相法聚乙烯冷凝操作模式撤热过程分析

Heat removal of gas-phase ethylene polymerization process under condensed mode operation

分析了气相法聚乙烯反应系统的撤热过程,研究了影响反应系统撤热的因素。实验结果表明,撤热过程主要包括循环气撤热、循环气冷却器撤热及调温水冷却器撤热。当调温水冷却器换热能力不足时,系统温度出现波动。反应负荷超过极限,会出现反应器温度剧烈波动等现象。在冷凝操作模式下,提高异戊烷浓度能有效提高反应系统撤热能力,异戊烷浓度一般控制在8%~12%(x)。循环水温度升高时需适当提高异戊烷浓度。循环水流量下降时需考虑清理过滤网。调温水冷却器末端温差升高时需及时调整操作参数,采取清理循环水入口过滤器、降低循环水温度等措施。根据调温水冷却器末端温差进行调控,可在确保装置稳定运行的前提下降低装置能耗。

The heat removal process of the gas-phase polyethylene reaction system was analyzed,and the factors affecting the heat removal of the reaction system were studied.The result shows that the heat removal process mainly includes the heat removal of the cycle gas,the cycle gas cooler,and the tempered water cooler.When the heat exchange capacity of the tempered water cooler is insufficient,the temperature of the system fluctuates.If the reaction load exceeds the limit,severe fluctuations of the reactor temperature may occur.In the condensed operation mode,increasing the isopentane concentration can effectively improve the heat removal capacity of the reaction system.The isopentane concentration is generally controlled at 8%-12%(x).When the temperature of the cooling water is increased,the isopentane concentration should be appropriately increased.When the cooling water flow drops,it is necessary to consider cleaning the filter.The increase in the temperature difference at the end of the tempered water cooler indicates that it is necessary to adjust the operating parameters in time,take measures to clean the cooling water inlet filter,and reduce the cooling water temperature.The regulation should be carried out according to the temperature difference at the end of the tempered water cooler,and the energy consumption can be reduced under the stable operation of the plant.