Dynamic modeling of gas phase propylene homopolymerization in fluidized bed reactors

Gas-solid flows have numerous industrial applications and are also found in natural processes. They are involved in industries like petrochemical, polymer, pharmaceutical, food and coal. Fluidization is a commonly used gas-solid operation and is widely used in production of polyethylene. Polyethylene is one of the most widely used thermoplastics. Over 60 million tons are produced worldwide every year by both gas-phase and liquid-phase processes. Gas-phase processes are more advantageous and use fluidized-bed reactors (e.g., UNIPOLTM PE PROCESS and Innovene process) for the polymerization reactions. In this work a chemical-reaction-engineering model incorporating a given catalyst size distribution and polymerization kinetics along with the quadrature method of moments is used to predict the final polymer size distribution and temperature. An Eulerian-Eulerian multi-fluid model based on the kinetic theory of granular flow is used to solve the fluidized-bed dynamics and predict behavior such as particle segregation, slug flow and other non-ideal phenomena.

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On the Production of Polyolefins with Bimodal Molecular Weight and Copolymer Composition Distributions in Catalytic Gas-Phase Fluidized-Bed Reactors

Macromolecular Theory and Simulations ◽

10.1002/mats.200700033 ◽

2007 ◽

Vol 16 (8) ◽

pp. 755-769 ◽

Cited By ~ 10

Author(s):

Christos Chatzidoukas ◽

Vassileios Kanellopoulos ◽

Costas Kiparissides

Keyword(s):

Molecular Weight ◽

Gas Phase ◽

Fluidized Bed ◽

Fluidized Bed Reactors ◽

Copolymer Composition

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Comparative simulation study of gas-phase propylene polymerization in fluidized bed reactors using aspen polymers and two phase models

Chemical Industry and Chemical Engineering Quarterly ◽

10.2298/ciceq111214038s ◽

2013 ◽

Vol 19 (1) ◽

pp. 13-24 ◽

Cited By ~ 6

Author(s):

Ahmad Shamiria ◽

M.A. Hussaina ◽

Farouq Mjallic ◽

Navid Mostoufid

Keyword(s):

Molecular Weight ◽

Gas Phase ◽

Production Rate ◽

Fluidized Bed ◽

Average Molecular Weight ◽

Phase Model ◽

Propylene Polymerization ◽

Flow Index ◽

Fluidized Bed Reactors ◽

Two Phase

A comparative study describing gas-phase propylene polymerization in fluidized-bed reactors using Ziegler-Natta catalyst is presented. The reactor behavior was explained using a two-phase model (which is based on principles of fluidization) as well as simulation using the Aspen Polymers process simulator. The two-phase reactor model accounts for the emulsion and bubble phases which contain different portions of catalysts with the polymerization occurring in both phases. Both models predict production rate, molecular weight, polydispersity index (PDI) and melt flow index (MFI) of the polymer. We used both models to investigate the effect of important polymerization parameters, namely catalyst feed rate and hydrogen concentration, on the product polypropylene properties, such as production rate, molecular weight, PDI and MFI. Both the two-phase model and Aspen Polymers simulator showed good agreement in terms of production rate. However, the models differed in their predictions for weight-average molecular weight, PDI and MFI. Based on these results, we propose incorporating the missing hydrodynamic effects into Aspen Polymers to provide a more realistic understanding of the phenomena encountered in fluidized bed reactors for polyolefin production.

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