Modeling Fouling Effects in LDPE Tubular Polymerization Reactors. 2. Heat Transfer, Computational Fluid Dynamics, and Phase Equilibria

Buchelli, Alberto; Call, Michael L.; Brown, Allen L.; Bird, A. J.; Hearn, Steve; Hannon, Joe

doi:10.1021/ie040158i

Cited by 9 publications

(11 citation statements)

References 9 publications

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“…One of the most fundamental and complex problems associated with the operation of LDPE tubular reactors is the severe and random fouling of the inner reactor wall due to a continuous polymer buildup. This phenomenon is difficult to predict by means of simple mechanistic models . There are two simple engineering ways to handle this problem.…”

Section: Reactor Mathematical Modelmentioning

confidence: 99%

Large-Scale Parameter Estimation in Low-Density Polyethylene Tubular Reactors

Zavala

Biegler

2006

Ind. Eng. Chem. Res.

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We propose a simultaneous approach for the solution of the associated DAE-constrained parameter estimation problem. Parameter estimation is an essential task in the development and on-line update of first-principles models for low-density polyethylene tubular reactors, consisting of nonlinear and stiff differential−algebraic equations (DAE). Our approach discretizes the reactor model equations in space, leading to a large-scale nonlinear program (NLP) that can be solved efficiently with state-of-the-art general-purpose NLP solvers. In doing so, more efficient estimation strategies can be considered, enabling the solution of challenging estimation problems including multiple data and large parameters sets. This approach is efficient in handling advanced regression problems such as the errors-in-variables-measured (EVM) formulation. The methodology is fast, robust, and reliable and can be used both for off-line and on-line purposes. Moreover, substantial improvements on the reactor model predictions have been obtained over previous approaches, making the model amenable for real-time optimization and control tasks.

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Section: Reactor Mathematical Modelmentioning

confidence: 99%

Large-Scale Parameter Estimation in Low-Density Polyethylene Tubular Reactors

Zavala

Biegler

2006

Ind. Eng. Chem. Res.

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“…Over the past 45 years, a number of papers have been published on the mathematical modeling of high pressure LDPE reactors. [ 2–26 ] Kiparissides et al. [ 25 ] developed a generalized multiscale modeling framework for the simulation of high‐pressure LDPE tubular reactors.…”

Section: Introductionmentioning

confidence: 99%

On the Elucidation of Polymer Fouling Mechanisms and Ethylene Decomposition in High‐Pressure LDPE Tubular Reactors

Kiparissides

2022

Macro Reaction Engineering

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In high-pressure free-radical ethylene polymerization tubular reactors, fouling often occurs due to polymer deposition onto the reactor's wall surface. This results in a decrease in the overall heat transfer coefficient. Note that a high-pressure tubular reactor must be capable of removing about half of the generated polymerization heat to the cooling water flowing into the reactor's jackets. Therefore, reactor fouling can have serious implications including decrease of heat removal rate and monomer conversion, increase in the overall initiator(s) consumption, change of polymer quality, decline of reactor's safe operation, and significant economic losses due to lower plant productivity and longer reactor maintenance periods. In rare cases, the loss of reactor's heat removal capacity may result in the appearance of local hot spots that eventually can trigger ethylene decomposition. In the present review paper, the fundamental physical and chemical phenomena regarding polymer fouling and ethylene decomposition in high-pressure low density polyethylene (LDPE) reactors are critically discussed. The effects of shear rate, polymer molecular weight, and wall surface energy on polymer adsorption and desorption are analyzed. Moreover, the effect of characteristic initiator decomposition and micromixing times and process conditions on initiator dispersion, polymer fouling, and ethylene decomposition are assessed.

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“…Research into millireactors and fouling is conducted both experimentally and, increasingly, computationally, including CFD modeling, see, e.g., refs − . One application of CFD modeling is the optimization of reactor design.…”

Section: Introductionmentioning

confidence: 99%

Reducing the Fouling Potential in a Continuous Polymerization Millireactor via Geometry Modification

Begall

Krieger

Recker

et al. 2018

Ind. Eng. Chem. Res.

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Continuous milli-scale reactors with internal mixing elements are increasingly used in the chemical industry and considered for polymerization processes. Their small scale makes them especially susceptible to fouling. Addressing this problem, this article presents a computational fluid dynamics (CFD) analysis of a Miprowa millireactor channel. The flow field is examined with the finite-element based software package COMSOL Multiphysics to identify areas of low velocity, generally prone to fouling during polymerization reactions. For simplicity, the flow is assumed incompressible and isothermal, using the material properties of water. Three geometry modifications to the mixing elements are proposed. Numerical simulations of the flow field around the proposed mixing elements show a reduction in areas with stagnating flow by 20%, reducing the fouling potential without substantially affecting other metrics such as the pressure loss.

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Modeling Fouling Effects in LDPE Tubular Polymerization Reactors. 2. Heat Transfer, Computational Fluid Dynamics, and Phase Equilibria

Cited by 9 publications

References 9 publications

Large-Scale Parameter Estimation in Low-Density Polyethylene Tubular Reactors

Large-Scale Parameter Estimation in Low-Density Polyethylene Tubular Reactors

On the Elucidation of Polymer Fouling Mechanisms and Ethylene Decomposition in High‐Pressure LDPE Tubular Reactors

Reducing the Fouling Potential in a Continuous Polymerization Millireactor via Geometry Modification

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