Batch to Conti Transfer of Polymer Production Processesстатья из журнала
Аннотация: Most specialty polymers up to now are produced in batch or semibatch reactors, due to their flexibility to produce many products from different recipes and easy adaptability to changing demands. Batch reactors, on the other hand, are strongly restricted in the ability to remove the heat of reaction so that the space-time yield is not very high. In addition, the batch modes of operation leads to the need for cleaning between the batches and variations of quality from batch to batch are an issue. In continuous production, on the other hand, the heat removal capacity is larger so that higher reaction rates (solids contents) can be realized, and hence the space-time yield is higher. Moreover, continuous processes can be more tightly controlled and require less cleaning as long as there are no product changeovers. The switch from batch to continuous production is one facet of process intensification which can lead to savings of energy and material, more compact and thus cheaper plants and improved sustainability and better economic performance. However, to transfer polymerization processes from the batch production mode to a continuous reactor is not trivial, as polymers are products by processes and changes of production regime may lead to changes of the product properties. This special issue of Macromolecular Reaction Engineering contains a set of papers on the transfer of polymer production processes from batch reactors to continuous reactors that cover a number of important issues that arise in such a transfer. Two different types of production are investigated: emulsion polymerization and polymerization in aqueous solutions. For the transfer from batch to continuous production, several aspects of the problem are considered, covering different scales from the molecules to plant scale: modeling of reactions and reactors, in situ monitoring of monomer conversion, control of production, and optimization of the production planning of a flexible continuous plant (Figure 1). The first two papers focus on free radical polymerization processes in heterogeneous media. Asua1 discusses the challenges and opportunities that are encountered when transferring emulsion polymer production from semibatch to continuous processes. On the basis of several examples related to coatings, pressure-sensitive adhesives, and flocculants, the key role of reactor technology is detailed. Various types of reactors (semibatch reactor, tubular reactor, and continuous-stirred tank) are compared for free radical polymerization in microemulsion or miniemulsion. Pauer and co-workers2 study the copolymerization of styrene and n-butyl acrylate in emulsion. They report the transfer of production from a semibatch reactor to a continuous tubular reactor. The seven following papers all deal with free radical polymerization (homopolymerization and copolymerization) in aqueous solutions. The work described in these papers was carried out within the framework of the European research project Flexible, Fast, and Future Production Processes (F3 Factory), led by the European chemical and pharmaceutical companies Bayer, BASF, Arkema, Astra-Zeneca, Rhodia (now Solvay), and Evonik. The overall aim of the European project F3 Factory was to design small to medium scale plants on the basis of standardized container assemblies for delocalized production. Within F3 Factory project, one industrial case study was dedicated to the production of water-soluble polymers.3 The design of a modular, multiproduct, and continuous plant for manufacturing of water-soluble polymers is addressed by Kohlmann et al.4 Two industrial case studies were selected: Homopolymerization of acrylic acid in the presence of a chain transfer agent and copolymerization of acrylic acid. Both polymerizations are carried out in aqueous solution. A modular continuous plant for demonstration was designed and built on the basis of the previous industrial case studies (recipes of batch reactors were available). Inline monitoring of monomer conversion is achieved using Raman spectroscopy. The flexibility of the continuous plant is demonstrated by operating two different polymerization processes in the same pilot plant and by producing several polymer grades by changing reaction conditions. In the specific case of acrylic acid copolymerization in aqueous solution, Chevrel et al.5 report the design of a pilot-scale continuous tubular reactor on the basis of data obtained from a lab-scale batch reactor. They demonstrate the great benefit of the acquisition of kinetic and rheological data using a novel rheo-Raman experimental device. These experimental data are shown to lead to a reasonable estimation of the performance of the continuous tubular reactor. Goerke et al.6 examine the transfer of semibatch copolymer production to a continuous process involving a tubular reactor with several side injections. These side injections mimic the continuous feed of the second monomer in a batch reactor. Due to the localized feed instead of a continuous feed along the tubular reaction with would correspond to the semibatch mode of operation, the range of polymer properties that can be achieved in the tubular reactor with side injections is restricted. A key role is played by the reactivity ratios of the two monomers. Meimaroglou et al.7 focus on the kinetic modeling of acrylic acid copolymerizations. A coupled deterministic-stochastic numerical approach is followed so as to combine speed, efficiency, and predictive capabilities. Model parameters are identified using experimental results from a pilot-scale reactor. Online monitoring of acrylic acid polymerization in a continuous pilot-scale tubular reactor was carried out for the first time using Raman spectroscopy. Chevrel et al.8 report that Raman spectroscopy was a useful analytical technique for online monitoring of monomer conversion. In addition, this technique could be used to determine the residence time distribution under reactive conditions. Hashemi et al.9 investigate the control of a continuous tubular reactor in which the polymerization of acrylic acid is carried out. Weight average molar mass of polymer and residual monomer content at the reactor outlet are selected as the quality constraints, and within these constraints, the throughput of the reactor is optimized by dynamic optimizing control. Finally, Schoppmeyer et al.10 investigate the campaign planning in response to a demand of six different polymers in a flexible modular production setup. The setup is chosen such that equipment can be moved between the two production lines to satisfy the needs of the different products. Cleaning times as well as production losses due to off-spec product are taken into account. The results show that short campaigns (weekly satisfaction of the demands) lead to significant losses whereas long campaigns (monthly demand satisfaction) lead to the need to store significant amounts of product. We hope that the readers of the journal will find this overview of recent results in batch to conti transfer of polymerization processes useful, in particular because not only the advantages and the potential but also the difficulties and restrictions are highlighted. The funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement No. 228867 (F3 Factory) is gratefully acknowledged. Alain Durand obtained an engineer degree in chemical engineering from ENSIC, Nancy, France, in 1995. He obtained a Ph.D. in Polymer Chemistry and Physical Chemistry from Université Pierre et Marie Curie, Paris, France, in 1998. He is currently the director of the Laboratory of Physical Chemistry of Macromolecules and professor of chemical engineering and polymer physical chemistry at Université de Lorraine, Nancy, France. His research interests cover polymer-based colloids, emulsions, particles, and polymerization processes. Sebastian Engell obtained a Dipl.-Ing. degree in Electrical Engineering from Ruhruniversität Bochum and a Dr.-Ing. degree and the Habilitation in control from the University of Duisburg, Germany. Since 1990 he is professor of Process Dynamics and Operations in the Department of Biochemical and Chemical Engineering at TU Dortmund. From 2002–2006 he was vice-rector for Research of TU Dortmund and in 2005 he was appointed fellow of the International Federation of Automatic Control. In 2012 he received an ERC Advanced Investigator Grant. He was the leader of the workpackage on Process Operations in the F3 project and had coordinated several European research and innovation projects.
Год издания: 2016
Авторы: Alain Durand, Sebastian Engell
Издательство: Wiley
Источник: Macromolecular Reaction Engineering
Ключевые слова: Innovative Microfluidic and Catalytic Techniques Innovation, Scientific Measurement and Uncertainty Evaluation, Advanced Control Systems Optimization
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Открытый доступ: bronze
Том: 10
Выпуск: 4
Страницы: 308–310