Operation of Flexible Multiproduct Modular Continuous Polymerization Plants

Schoppmeyer, Christian; Vermue, Henry; Subbiah, Subanatarajan; Kohlmann, Daniel; Ferlin, Patrick; Engell, Sebastian

doi:10.1002/mren.201500044

Cited by 9 publications

(5 citation statements)

References 22 publications

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“…The reactor investigated in this work has been designed to produce different polymers or different grades of a polymer and therefore studying the changeover between different products is of interest. Schoppmeyer et al have showed that the duration of the changeover has a strong influence on the economics of a process. Our approach to control the changeover scenario is to use a different cost function in this phase and to drive the properties of the product to a region which are considered as in‐spec for the new product (with some tolerance) in the shortest possible time.…”

Section: Resultsmentioning

confidence: 99%

“…Schoppmeyer et al [ 32 ] have showed that the duration of the changeover has a strong infl uence on the economics of a process. Our approach to control the changeover scenario is to use a different cost function in this phase and to drive the properties of the product to a region which are considered as in-spec for the new product NMPC PF Figure 21.…”

Section: Changeover Scenariomentioning

confidence: 99%

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Optimizing Control and State Estimation of a Continuous Polymerization Process in a Tubular Reactor with Multiple Side‐Streams

Hashemi

Kohlmann

Engell

2016

Macro Reaction Engineering

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reactors by continuous ones. The reactor system which is investigated here comprises several inputs and due to the near plug fl ow characteristics between the inputs and the outputs, reacts to the changes of the infl ows with large time delays. Model-based optimizing control is the obvious candidate to control such a multi-input plants with significant delays. While the standard implementations of model predictive control penalize the deviations of the states or outputs from reference values and the control moves in the cost function, in this work the controller is formulated to account directly for the economics of the reactor system while the product quality parameters are imposed as constraints. [ 1 ] Some applications of optimizing control can be found in refs. [ 27 -30 ] . Limited computation power and lack of effi cient optimization algorithms have caused thatIn this contribution, a nonlinear model-based optimizing control for continuous polymerization of acrylic acid in tubular reactors with multiple side injections of monomer is developed. The background of this work is to transfer the production of polymers from semibatch to continuous operations. The confi guration of the tubular reactor, which imposes long delays between the inputs and the measurements, and the lack of intermediate measurements as well as the nonlinear reaction kinetics and sharp moving fronts of concentrations when the infl ows are changed, make the application of the optimizing control very challenging. In order to simulate the sharp fronts of the reactor system faithfully and fast, the spatial domain of the partial differential equations model of the tubular reactor is discretized by applying the weighted essentially non-oscillatory scheme. We formulate the controller such that it optimizes the productivity of the reactor directly, while the product quality parameters are imposed as constraints. A particle fi lter is implemented to estimate the states of the reactor system and to initialize the process model. The simulation results show that the controller can increase the product throughput considerably compared to an initial operating point and has a robust performance against the measurement noise. Furthermore, the effect of formulating the quality constraints as hard or soft constraints as well as a changeover scenario between the different grades of a polymer are studied.

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Section: Resultsmentioning

confidence: 99%

Section: Changeover Scenariomentioning

confidence: 99%

Optimizing Control and State Estimation of a Continuous Polymerization Process in a Tubular Reactor with Multiple Side‐Streams

Hashemi

Kohlmann

Engell

2016

Macro Reaction Engineering

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“…For example, models have been successfully used to predict the transition of the solution polymerization of non-ionized acrylic acid [6], [7] or to study the impact of micromixing in the solution polymerization of methyl methacrylate (MMA) in a continuous stirred tank reactor (CSTR) [8]. This is a topic of primary interest from both academic and industrial points of view, as testified by several recent publications [6], [9], [10]. In particular, companies have interest in the production of large volumes of polymers always preserving their quality, in order not to alter their portfolio and ensure continuity in their business.…”

Section: Introductionmentioning

confidence: 99%

Free-radical polymerization of methacrylic acid: From batch to continuous using a stirred tank reactor

Ilare

Manfredini

Sponchioni

et al. 2021

Chemical Engineering and Processing - Process Intensification

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“…The logistic aspects of such plants are investigated in detail in ref. . The transfer of batch recipes from a batch plant to a plug‐flow reactor (PFR) is limited only by factors such as the geometry of the reactor and the minimum flow velocity for sufficient heat transfer and a sharp residence time distribution.…”

Section: Introductionmentioning

confidence: 99%

Transfer of Semibatch Processes to Continuous Processes with Side Injections—Opportunities and Limitations

Goerke

Kohlmann

Engell

2016

Macro Reaction Engineering

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The transfer of copolymerization processes from discontinuous plants to continuous plants has become a topic of industrial interest in the recent years. The motivations for such a transfer are better product consistency, smaller capital investment, and smaller footprint of the plants. However the experiences of the F3 project show that some copolymerization processes cannot be transferred to continuous production if the product quality must remain the same because in a continuous reactor, feeds can be added only at certain points along the reactor. This paper discusses the transferability of semibatch polymerization processes to a continuous plug-fl ow reactor with side injections in a generic fashion. Transferability of a semibatch recipe here means the possibility of the production of the same product in both modes of operation (semibatch and continuous). To determine the limits of the transferability from semibatch to continuous production, a model-based analysis has been performed based on a simplifi ed kinetic model and realistic kinetic para meters. The ranges of product qualities that can be produced in both modes of operation and the minimum changes in the product qualities, if no 1:1 transfer is possible are determined by means of model-based optimization. Besides the numerical results, also an analytical treatment is presented. This provides a sound basis for an analysis of the transferability from a kinetic and an economic point of view.

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Operation of Flexible Multiproduct Modular Continuous Polymerization Plants

Cited by 9 publications

References 22 publications

Optimizing Control and State Estimation of a Continuous Polymerization Process in a Tubular Reactor with Multiple Side‐Streams

Optimizing Control and State Estimation of a Continuous Polymerization Process in a Tubular Reactor with Multiple Side‐Streams

Free-radical polymerization of methacrylic acid: From batch to continuous using a stirred tank reactor

Transfer of Semibatch Processes to Continuous Processes with Side Injections—Opportunities and Limitations

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