乙烯气相聚合过程中颗粒的稳态热质传递模型研究.pdf

乙烯气相聚合过程中颗粒的稳态热质传递模型研究1* ** 崔雅萍 冯连芳 顾雪萍 王嘉骏 （化学工程国家重点实验室，浙江大学化学工程与生物工程学系，杭州 310027） 笪文忠 胡庆云 （中国石化扬子石化公司研究院，南京 210048） 摘要：为考察乙烯气相聚合过程中颗粒内部单体浓度及温度分布，建立并求解颗粒的稳态热质传递模型：等温等浓度模型 和变温变浓度模型。前者假设颗粒内单体浓度及温度均匀分布，仅考虑颗粒边界层的对流传质及传热；后者认为颗粒内存在单 体扩散及热传导，同时颗粒边界层与本体进行对流传质及传热。模拟结果表明：粒径小的聚合物颗粒内单体浓度低而温度高； 随粒径长大，颗粒内浓度升高温度降低，趋于颗粒外的气相浓度和温度；聚合物颗粒内的温度梯度较小，主要温度梯度集中于 颗粒表面与气相界面之间。 关键词：聚合 颗粒模型 稳态 传质 传热 Study on Steady-State Heat and Mass Transfer Models for Particles in Ethylene Gas-Phase Polymerization Process CUI Yaping FENG Lianfang GU Xueping WANG Jiajun (State Key Laboratory of Chemical Engineering, Zhejiang University, Hangzhou 310027) DA Wenzhong, HU Qingyun ( Research Institute of Yangzi Petrochemical Co., Ltd., Nanjing 210048 ) Abstract: Two steady state heat and mass transfer models are developed to examine intra-particle concentration and temperature profile in ethylene gas-phase polymerization. Uniform concentration and temperature model assumes uniform monomer concentration and temperature inside particle and considers boundary layer mass and heat transfer resistance by convection, while distributed concentration and temperature model takes into account intra-particle monomer diffusion and heat conduction as well as boundary layer mass and heat transfer by convection. It is found that smaller particles have lower concentration and higher temperature, as particle grows, monomer concentration increases and temperature decreases to bulk values; intra-particle temperature gradient is only a few centigrade and the main temperature gradient is located between particle surface and bulk gas. Key words: polymerization, particle model, steady