On the residence time distribution in reactors with non-uniform velocity profiles: The horizontal stirred bed reactor for polypropylene production

Dittrich, Christoph; Mutsers, S.M.P.

doi:10.1016/j.ces.2007.06.031

Cited by 25 publications

(30 citation statements)

References 8 publications

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“…Harshe et al developed a generalized dynamic model based on a mixing cell approach coupled with population balances to model the PSD of polypropylene made in gas phase reactors. Dittrich and Mutsers proposed a new model to study the effect of reactor RTD on the PSD of polyolefin particles made on horizontal stirred gas‐phase reactors that did not rely on the commonly used CSTR‐in‐series approach, but rather on experimental RTDs. In a more sophisticated analysis, Fan et al combined population balances with a computational fluid dynamics model to compare the PSD of predicted and experimental polyethylene particles made in a fluidized bed reactor.…”

Section: Introductionmentioning

confidence: 99%

A Monte Carlo Method to Quantify the Effect of Reactor Residence Time Distribution on Polyolefins Made with Heterogeneous Catalysts: Part I—Catalyst/Polymer Particle Size Distribution Effects

Soares

Romero

2017

Macro Reaction Engineering

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Polyolefins are commercially produced in continuous reactors that have a broad residence time distribution (RTD). Most of these polymers are made with heterogeneous catalysts that also have a particle size distribution (PSD). These are totally segregated systems, in which the catalyst/polymer particle can be seen as a microreactor operated in semibatch mode, where the reagents (olefins, hydrogen, etc.) are fed continuously to the catalyst/polymer particle, but no polymer particle can leave. The reactor RTD has a large influence on the PSD of the polymer particles leaving the reactor, as well as in polymer microstructure and properties, polymerization yield, and composition of reactor blends. This article proposes a Monte Carlo model that can describe how particle RTD in a single or a series of reactors can affect the PSD of polymer particles made under a variety of operation conditions. It is believed that this is the most flexible model ever proposed to model this phenomenon, and can be easily modified to track all properties of interest during polyolefin production in continuous reactors with heterogeneous catalysts.

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Section: Introductionmentioning

confidence: 99%

A Monte Carlo Method to Quantify the Effect of Reactor Residence Time Distribution on Polyolefins Made with Heterogeneous Catalysts: Part I—Catalyst/Polymer Particle Size Distribution Effects

Soares

Romero

2017

Macro Reaction Engineering

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“…Other authors also used the concept of equivolume CSTRs in series for describing a HSBR 2, 16. More recently, Dittrich and Mutsers11 proposed a semimechanistic model to take into account mixing and mass transfer. They recommended not using flow models with a lumped parameter for backmixing but describing axial net transport and backmixing separately then superimposing them for flow modeling.…”

Section: Mathematical Modelsmentioning

confidence: 99%

“…In FBRs, agglomerization may occur due to the temperature gradient in the bed and frequent particle collision 8. However, in HSBRs, the relatively slow particle motion together with an excellent heat removal capacity may avoid particle agglomeration 11, 13 Particle breakage is negligible.…”

Section: Mathematical Modelsmentioning

confidence: 99%

“…The literature regarding the effect of residence time distribution (RTD) on the polymer PSD is also relatively scarce. Dittrich and Mutsers11 proposed a modeling approach describing the RTD in a HSBR and simulated the PSD with different RTD models. For simplicity, the intraparticle mass‐ and heat‐transfer resistances were not considered in their work.…”

Section: Introductionmentioning

confidence: 99%

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Modeling and simulation of polypropylene particle size distribution in industrial horizontal stirred bed reactors

Tian

et al. 2012

J of Applied Polymer Sci

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This work aims at developing a steadystate particle size distribution (PSD) model for predicting the size distribution of polypropylene particles in the outflow streams of propylene gas-phase horizontal stirred bed reactors (HSBR), on the one hand and investigating the effect of the catalyst residence time distribution (RTD) on the polymer PSD, on the other hand. The polymer multilayer model (PMLM) is used to describe the growth of a single particle. Knowing the PSD and RTD of a Ziegler-Natta type of catalyst and polymerization kinetics, this model allows calculating the polymer PSD of propylene polymerization in the HSBRs. The calculated polypropylene PSDs agree well with those obtained from the indus-trial reactors. The results reveal that both the PSD and the RTD of the catalyst affect the polymer PSD but in different manners. The effect of RTD on the PSD is less significant in the case of a nonuniform size catalyst feed. This model also allows investigating the effects of other process parameters on the polymer PSD under steady-state conditions, including intraparticle mass-and heat-transfer limitations, initial catalyst size, and polymer crystallinity.

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“…This type of approach allows us to understand the general influence of reaction conditions on kinetics and polymer properties and can even be used to define control policies, grade changeover, etc. However, these models tend to be ‘averaged’ models; in other words they rely heavily on engineering correlations to define overall bed properties, average velocities of gas and particle phases in the reactor, etc 3–7. Since correlations by nature impose an averaged or pseudo‐homogeneous view on the entire reactor, it is not easy to use such an approach for modelling hot spot formation, the effect of particle/particle interaction and similarly important issues.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer in Gas‐Phase Olefin Polymerisation: A Study of Particle/Surface Interactions

Eriksson

Weickert

McKenna

2010

Macro Reaction Engineering

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This work focuses on the heat exchange between a polymer particle and the reactor wall for low gas velocities. The role of different wall materials (or heat transfer conditions) is investigated with an eye to understanding how this influences the likelihood of build up of wall sheeting via melting of particles. The temperature profiles inside growing polymer particles in the vicinity of the reactor wall when it is clean (steel) or covered with a layer of non‐reactive polymer are simulated. As a comparison, we have also simulated glass reactor walls to represent bench‐scale polymerisation equipment. The results can help to understand how how we can compare results from bench‐scale experiments to industrial scale units.

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On the residence time distribution in reactors with non-uniform velocity profiles: The horizontal stirred bed reactor for polypropylene production

Cited by 25 publications

References 8 publications

A Monte Carlo Method to Quantify the Effect of Reactor Residence Time Distribution on Polyolefins Made with Heterogeneous Catalysts: Part I—Catalyst/Polymer Particle Size Distribution Effects

A Monte Carlo Method to Quantify the Effect of Reactor Residence Time Distribution on Polyolefins Made with Heterogeneous Catalysts: Part I—Catalyst/Polymer Particle Size Distribution Effects

Modeling and simulation of polypropylene particle size distribution in industrial horizontal stirred bed reactors

Heat Transfer in Gas‐Phase Olefin Polymerisation: A Study of Particle/Surface Interactions

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