淤浆聚合体系乙烯溶解度及传质系数测定

Determination of Solubility and Mass Transfer Coefficient of Ethylene in Slurry Polymerization System

对采用淤浆聚合法聚合生成超高相对分子质量聚乙烯过程中的传质过程进行了研究,考察了压力、温度对平衡溶解度的影响以及搅拌速率和物料对传质系数K_L的影响规律。结果表明:乙烯溶解度随气相中乙烯压力的升高而线性增加,气液平衡关系符合亨利定律;温度升高,气体溶解度减小;搅拌速率增大,相应的传质系数线性增大;加入聚乙烯颗粒会使吸收速率降低,物料量与传质系数基本呈反比例关系。

The mass transfer process of polymerization of ultra-high molecular weight polyethylene（PE） using slurry polymerization was studied. The effects of pressure and temperature on gas solubility, stirring rate and polyethylene particles on mass transfer coefficient KL were investigated. Experiment results show that the vapor-liquid equilibrium relationship of system ethylene-hexane conforms to Henry＇s law and the solubility of ethylene increase linearly with the increase of ethylene pressure in the gas phase. The solubility of ethylene in hexane decreases with increasing temperature. The corresponding transfer coefficient increases linearly with stirring rate. The presence of polyethylene particles could decrease the absorption rate of ethylene and the relationship between PE quality and mass transfer coefficient is almost in an inverse proportion.