Instability analysis of the fluidized bed for ethylene polymerization with condensed mode operation
Instability analysis of the fluidized bed for ethylene polymerization with condensed mode operation
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DOI：
10.1021/ie001121a
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发表时间：
2002-04
影响因子：
4.2
通讯作者：
Yongrong Yang;J. Q. Yang;Wei Chen;S. Rong
中科院分区：
文献类型：
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作者：
Yongrong Yang;J. Q. Yang;Wei Chen;S. Rong
在气相流化床乙烯聚合工艺中，由于聚合物生产的时空产率大幅提高，因此所谓的冷凝模式操作是目前比较流行的。然而，尽管流化床的不稳定性在商业上具有至关重要的意义，但在理论上从未对其进行过分析。本文首次提出了“湿态不稳定性”的机理，用于流化颗粒团聚的不稳定性分析。重组分在聚合物颗粒上的吸收被认为通过形成液体桥使颗粒更粘。在团聚体力平衡的基础上，建立了一种新的模型来预测流化气流中允许存在的凝聚剂（异戊烷）的最大摩尔分数，从而区分流化床的不稳定操作区。结果表明，理论计算与实际应用结果吻合较好。
The so-called condensed mode operation is more fashionable at present in the gas-phase fluidized-bed ethylene polymerization process because of a substantial increase in the space-time yield of polymer production. However, the instability of the fluidized bed in condensed mode operation has never been analyzed theoretically before regardless of its critical importance of commerce. The mechanism of “wet state instability” was first proposed in this paper for the instability analysis due to agglomeration of fluidizing particles. The absorption of heavy components on the polymer particles was assumed to make particles stickier by formation of a liquid bridge. On the basis of a force balance of the agglomerate, a novel model has been developed to predict the maximal mole fraction of the condensed agent (isopentane) permissively existing in the fluidizing gas stream and then to distinguish the unstable operating zone of the fluidized bed. It is found that the theoretical calculation agrees with the industrial ...