CFD analysis of micromixing effects on polymerization in tubular low-density polyethylene reactors

Kolhapure, Nitin H.; Fox, Rodney O.

doi:10.1016/s0009-2509(98)00370-4

Cited by 54 publications

(62 citation statements)

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“…[56] In general, macro-scale effects can result in a significantly different overall polymerization rate and average polymer properties than expected based on perfect mixing at the macro-scale. [57,58] It should be stressed that a detailed understanding of the importance of these macro-effects requires an accurate knowledge of mixing phenomena at the micro-scale. To a first approximation, it can be expected that at laboratory scale the apparent reaction rates are only determined by the chemical reactivities and molecular diffusion phenomena or thus micro-scale effects.…”

Section: Guymentioning

confidence: 99%

The Crucial Role of Diffusional Limitations in Controlled Radical Polymerization

D’hooge

Reyniers

Marin

2013

Macro Reaction Engineering

124

146

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The importance of diffusional limitations in controlled radical polymerization at laboratory scale and in homogeneous medium is highlighted using different diffusion models. In particular, a coupled ‘parallel’ encounter pair model is introduced which allows a rigorous description of the influence of diffusional limitations on the activation/deactivation process. Diffusional limitations on termination have a significant influence, whereas those on the activation/deactivation process can disturb the regular growth pattern at high conversion if the mediating agent is a sufficiently bulky species. Diffusional limitations on initiation are only important in case radical initiator is still present at high conversion.

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Section: Guymentioning

confidence: 99%

The Crucial Role of Diffusional Limitations in Controlled Radical Polymerization

D’hooge

Reyniers

Marin

2013

Macro Reaction Engineering

124

146

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“…Finally, the implementation of ISAT reported in this work is in no way limited to methane thermochlorination kinetics. Indeed, in our research group it has also been successfully employed for full PDF simulations of free-radical polymerization of ethylene using a detailed kinetic scheme including ethylene decomposition, 7 and can be easily implemented for other kinetic schemes such as the 116 species/447 reaction Exxon model. 21 …”

Section: Discussionmentioning

confidence: 99%

“…5 Recently, CFD simulation of turbulent reacting flows, including detailed chemistry schemes, has received considerable attention due to the availability of faster computers, the development of new algorithms, and the establishment of elementary reaction schemes. [6][7][8] However, for the methane thermochlorination reaction a key problem remaining is the stiffness of the governing differential equations due to the wide range of chemical time scales. Therefore chemical reactor simulations often use a simplified model, either of the flow or of the chemistry (see ref 9 for a detailed discussion of the difficulties associated with kinetic model reduction).…”

Section: Introductionmentioning

confidence: 99%

Computational Fluid Dynamics Simulation of Chemical Reactors: Application of in Situ Adaptive Tabulation to Methane Thermochlorination Chemistry

Shah

Fox

1999

Ind. Eng. Chem. Res.

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Recently, a novel algorithmin situ adaptive tabulationhas been proposed to effectively incorporate detailed chemistry in computational fluid dynamics (CFD) simulations for turbulent reacting flows. In this work, detailed tests performed on a pairwise-mixing stirred reactor (PMSR) model are presented implementing methane thermochlorination chemistry to validate the in situ adaptive tabulation (ISAT) algorithm. The detailed kinetic scheme involves 3 elements (H, C, Cl) and 38 chemical species undergoing a total of 152 elementary reactions. The various performance issues (error control, accuracy, storage requirements, speedup) involved in the implementation of detailed chemistry in particle-based methods (full PDF methods) are discussed. Using an error tolerance of εtol = 2 ? 10-4, sufficiently accurate results with minimal storage requirements and significantly less computational time than would be required with direct integration are obtained. Based on numerous test simulations, an error tolerance in the range of 10-3?10-4 is found to be satisfactory for carrying out full PDF simulations of methane thermochlorination reactors. The results presented here demonstrate that the implementation of ISAT makes possible the hitherto formidable task of implementing detailed chemistry in CFD simulations of methane thermochlorination reactors. Disciplines Catalysis and Reaction Engineering | Chemical Engineering CommentsThis article is from Industrial & Engineering Chemistry Research38(1999) Recently, a novel algorithmsin situ adaptive tabulationshas been proposed to effectively incorporate detailed chemistry in computational fluid dynamics (CFD) simulations for turbulent reacting flows. In this work, detailed tests performed on a pairwise-mixing stirred reactor (PMSR) model are presented implementing methane thermochlorination chemistry to validate the in situ adaptive tabulation (ISAT) algorithm. The detailed kinetic scheme involves 3 elements (H, C, Cl) and 38 chemical species undergoing a total of 152 elementary reactions. The various performance issues (error control, accuracy, storage requirements, speed-up) involved in the implementation of detailed chemistry in particle-based methods (full PDF methods) are discussed. Using an error tolerance of tol ) 2 × 10 -4 , sufficiently accurate results with minimal storage requirements and significantly less computational time than would be required with direct integration are obtained. Based on numerous test simulations, an error tolerance in the range of 10 -3 -10 -4 is found to be satisfactory for carrying out full PDF simulations of methane thermochlorination reactors. The results presented here demonstrate that the implementation of ISAT makes possible the hitherto formidable task of implementing detailed chemistry in CFD simulations of methane thermochlorination reactors.

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“…The first efforts in this area [104,105] concern themselves with the prediction of temperature and conversion profiles in the reactors; to simplify the calculational load they consider only initiation, propagation, and termination reactions. More recently, Kolhapure and Fox [106] incorporated a more complete kinetic scheme to allow the prediction of polymer MW, polydispersity, and average branching number. These CFD studies can point the way to improved reactor design and operation; for example, by examining the importance of initiator distribution at the injection point, and defining conditions for stable reactor operation [106].…”

Section: Computational Fluid Dynamics (Cfd)mentioning

confidence: 99%

“…More recently, Kolhapure and Fox [106] incorporated a more complete kinetic scheme to allow the prediction of polymer MW, polydispersity, and average branching number. These CFD studies can point the way to improved reactor design and operation; for example, by examining the importance of initiator distribution at the injection point, and defining conditions for stable reactor operation [106]. An article in 2000 discussed the implementation of CFD calculations within a process simulation package [107].…”

Section: Computational Fluid Dynamics (Cfd)mentioning

confidence: 99%

Free‐Radical Polymerization: Homogeneous

Hutchinson¹

2005

Handbook of Polymer Reaction Engineering

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Free-radical polymerization (FRP) is one of the most important commercial processes for preparing high molecular weight polymers. It can be applied to almost all vinyl monomers under mild reaction conditions over a wide temperature range and, although requiring the absence of oxygen, is tolerant of water. Multiple monomers can be easily copolymerized via FRP, leading to the preparation of an endless range of copolymers with properties dependent on the proportion of the incorporated comonomers. This chapter will provide an overview of the kinetics and mechanisms, and the techniques used to construct mathematical representations of bulk and solution FRP. The description will also serve as a good base for the suspension and emulsion FRP chapters that follow. FRP Properties and ApplicationsPolymers produced via free-radical chemistry include the following major families:Low-density polyethylene (LDPE) and copolymers, used primarily in films and packaging applications. LDPE has density of <0.94 g cm À3 , and is produced via high-pressure free-radical polymerization; polyethylenes of higher density (and polypropylene) are produced via transition metal catalysis, as described elsewhere (see Chapter 8). Poly(vinyl chloride) and copolymers, used primarily to produce pipe and fittings, flooring material, and films and sheet. Polystyrene and its co-and terpolymers with acrylonitrile and butadiene. Homopolymer is used for packaging and containers, while the acrylonitrile-containing polymers are used for various molded products in the appliance, electronics, and

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CFD analysis of micromixing effects on polymerization in tubular low-density polyethylene reactors

Cited by 54 publications

References 0 publications

The Crucial Role of Diffusional Limitations in Controlled Radical Polymerization

The Crucial Role of Diffusional Limitations in Controlled Radical Polymerization

Computational Fluid Dynamics Simulation of Chemical Reactors: Application of in Situ Adaptive Tabulation to Methane Thermochlorination Chemistry

Free‐Radical Polymerization: Homogeneous

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