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Author: W. H. B. W. Ibrahim Publisher: ISBN: Category : Languages : en Pages :
Book Description
Dynamic modelling and optimization of three different processes namely (a) bulk polymerization of styrene, (b) solution polymerization of methyl methacrylate (MMA) and (c) emulsion copolymerization of Styrene and MMA in batch and semi-batch reactors are the focus of this work. In this work, models are presented as sets of differential-algebraic equations describing the process. Different optimization problems such as (a) maximum conversion (Xn), (b) maximum number average molecular weight (Mn) and (c) minimum time to achieve the desired polymer molecular properties (defined as pre-specified values of monomer conversion and number average molecular weight) are formulated. Reactor temperature, jacket temperature, initial initiator concentration, monomer feed rate, initiator feed rate and surfactant feed rate are used as optimization variables in the optimization formulations. The dynamic optimization problems were converted into nonlinear programming problem using the CVP techniques which were solved using efficient SQP (Successive Quadratic Programming) method available within the gPROMS (general PROcess Modelling System) software. The process model used for bulk polystyrene polymerization in batch reactors, using 2, 2 azobisisobutyronitrile catalyst (AIBN) as initiator was improved by including the gel and glass effects. The results obtained from this work when compared with the previous study by other researcher which disregarded the gel and glass effect in their study which show that the batch time operation are significantly reduced while the amount of the initial initiator concentration required increases. Also, the termination rate constant decreases as the concentration of the mixture increases, resulting rapid monomer conversion. The process model used for solution polymerization of methyl methacrylate (MMA) in batch reactors, using AIBN as the initiator and Toluene as the solvent was improved by including the free volume theory to calculate the initiator efficiency, f. The effects of different f was examined and compared with previous work which used a constant value of f 0.53. The results of these studies show that initiator efficiency, f is not constant but decreases with the increase of monomer conversion along the process. The determination of optimal control trajectories for emulsion copolymerization of Styrene and MMA with the objective of maximizing the number average molecular weight (Mn) and overall conversion (Xn) were carried out in batch and semi-batch reactors. The initiator used in this work is Persulfate K2S2O8 and the surfactant is Sodium Dodecyl Sulfate (SDS). Reduction of the pre-batch time increases the Mn but decreases the conversion (Xn). The sooner the addition of monomer into the reactor, the earlier the growth of the polymer chain leading to higher Mn. Besides that, Mn also can be increased by decreasing the initial initiator concentration (Ci0). Less oligomeric radicals will be produced with low Ci0, leading to reduced polymerization loci thus lowering the overall conversion. On the other hand, increases of reaction temperature (Tr) will decrease the Mn since transfer coefficient is increased at higher Tr leading to increase of the monomeric radicals resulting in an increase in termination reaction.
Author: W. H. B. W. Ibrahim Publisher: ISBN: Category : Languages : en Pages :
Book Description
Dynamic modelling and optimization of three different processes namely (a) bulk polymerization of styrene, (b) solution polymerization of methyl methacrylate (MMA) and (c) emulsion copolymerization of Styrene and MMA in batch and semi-batch reactors are the focus of this work. In this work, models are presented as sets of differential-algebraic equations describing the process. Different optimization problems such as (a) maximum conversion (Xn), (b) maximum number average molecular weight (Mn) and (c) minimum time to achieve the desired polymer molecular properties (defined as pre-specified values of monomer conversion and number average molecular weight) are formulated. Reactor temperature, jacket temperature, initial initiator concentration, monomer feed rate, initiator feed rate and surfactant feed rate are used as optimization variables in the optimization formulations. The dynamic optimization problems were converted into nonlinear programming problem using the CVP techniques which were solved using efficient SQP (Successive Quadratic Programming) method available within the gPROMS (general PROcess Modelling System) software. The process model used for bulk polystyrene polymerization in batch reactors, using 2, 2 azobisisobutyronitrile catalyst (AIBN) as initiator was improved by including the gel and glass effects. The results obtained from this work when compared with the previous study by other researcher which disregarded the gel and glass effect in their study which show that the batch time operation are significantly reduced while the amount of the initial initiator concentration required increases. Also, the termination rate constant decreases as the concentration of the mixture increases, resulting rapid monomer conversion. The process model used for solution polymerization of methyl methacrylate (MMA) in batch reactors, using AIBN as the initiator and Toluene as the solvent was improved by including the free volume theory to calculate the initiator efficiency, f. The effects of different f was examined and compared with previous work which used a constant value of f 0.53. The results of these studies show that initiator efficiency, f is not constant but decreases with the increase of monomer conversion along the process. The determination of optimal control trajectories for emulsion copolymerization of Styrene and MMA with the objective of maximizing the number average molecular weight (Mn) and overall conversion (Xn) were carried out in batch and semi-batch reactors. The initiator used in this work is Persulfate K2S2O8 and the surfactant is Sodium Dodecyl Sulfate (SDS). Reduction of the pre-batch time increases the Mn but decreases the conversion (Xn). The sooner the addition of monomer into the reactor, the earlier the growth of the polymer chain leading to higher Mn. Besides that, Mn also can be increased by decreasing the initial initiator concentration (Ci0). Less oligomeric radicals will be produced with low Ci0, leading to reduced polymerization loci thus lowering the overall conversion. On the other hand, increases of reaction temperature (Tr) will decrease the Mn since transfer coefficient is increased at higher Tr leading to increase of the monomeric radicals resulting in an increase in termination reaction.
Author: R. Paulen Publisher: Elsevier Inc. Chapters ISBN: 012808619X Category : Science Languages : en Pages : 16
Book Description
We study dynamic optimization of a lab-scale semi-batch emulsion copolymerization reactor for styrene and butyl acrylate in the presence of n-dodecyl mercaptan as chain transfer agent (CTA). The previously developed mathematical model of the polymerization reactions is used to predict the glass transition temperature of produced polymer, the global monomer conversion, the number and weight average molecular weights, the particle size distribution, and the amount of residual monomers. This model is implemented within gPROMS environment for modeling and optimization. It is desired to compute optimal profiles of feed rate of pre-emulsioned monomers and CTA which optimize properties (quantitative as well as qualitative) of polymers produced during the reaction subject to operational conditions and constraints.
Author: Iván-Dario Gil Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
In this work, modeling, simulation, dynamic optimization and nonlinear control of an industrial emulsion polymerization process to produce poly-vinyl acetate (PVAc) are proposed. The reaction is modeled as a two-phase system composed of an aqueous phase and a particle phase. A detailed model is used to calculate the weight average molecular weight, the number average molecular weight and the dispersity. The moments of the growing and dead chains are used to represent the state of the polymer and to calculate the molecular weight distribution (MWD). The case study corresponds to an industrial reactor operated at a chemical company in Bogotá. An industrial scale reactor (11 m3 of capacity) is simulated where a semi-batch emulsion polymerization reaction of vinyl acetate is performed. Dynamic optimization problem is solved directly using a Nonlinear Programming solver. Integration of differential equations is made using Runge-Kutta method. Three different optimization problems are solved from the more simplistic (only one control variable: reactor temperature) to the more complex (three control variables : reactor temperature, initiator flow rate and monomer flow rate) in order to minimize the reaction time. A reduction of 25% of the batch time is achieved with respect to the normal operating conditions applied at the company. The results show that is possible to minimize the reaction time while some polymer desired qualities (conversion, molecular weight and solids content) satisfy the defined constraints. A nonlinear geometric control technique by using input/output linearization is adapted to the reactor temperature control. An extended Kalman filter (EKF) is implemented to estimate unmeasured states and it is tested in different cases including a robustness study where model errors are introduced to verify its good performance. After verification of controller performance, some process changes were proposed in order to improve process productivity and polymer quality. Finally, the optimal temperature profile and optimal feed policies of the monomer and initiator, obtained in a dynamic optimization step, are used to provide the optimal set points for the nonlinear control. The results show that the nonlinear controller designed here is appropriate to follow the optimal temperature trajectories calculated previously.
Author: Joseph Schork Publisher: Routledge ISBN: 1351457942 Category : Science Languages : en Pages : 374
Book Description
This reference and text provides an in-depth description of developments in control techniques and their application to polymerization reactors and offers important introductory background information on polymerization reaction engineering.;Discussing modelling, identification, linear, nonlinear and multivariable schemes, Control of Polymerization Reactors: presents all available techniques that can be used to control reactors properly for optimal performance; shows how to manipulate pivotal variables that affect reactor control; examines methods for deriving dynamic process models to improve reactor efficiency; reviews reactor control problems and points out end-use properties; supplies methods for measuring process variables, and ways to estimate variables that can't be measured; and explains how single-input, single-output (SISO) strategies can be effectively used for control.;Filled with illustrative examples to clarify concepts, including more than 730 figures, tables and equations, Control of Polymerization Reactors is intended for use as a reference for chemical, process development, process design, research and development, control systems, and polymer engineers; and polymer chemists and physicists; as well as a text for upper-level undergraduate and graduate students in polymerization reactor control courses.
Author: Prashant Mhaskar Publisher: Springer ISBN: 3030041409 Category : Technology & Engineering Languages : en Pages : 335
Book Description
Modeling and Control of Batch Processes presents state-of-the-art techniques ranging from mechanistic to data-driven models. These methods are specifically tailored to handle issues pertinent to batch processes, such as nonlinear dynamics and lack of online quality measurements. In particular, the book proposes: a novel batch control design with well characterized feasibility properties; a modeling approach that unites multi-model and partial least squares techniques; a generalization of the subspace identification approach for batch processes; and applications to several detailed case studies, ranging from a complex simulation test bed to industrial data. The book’s proposed methodology employs statistical tools, such as partial least squares and subspace identification, and couples them with notions from state-space-based models to provide solutions to the quality control problem for batch processes. Practical implementation issues are discussed to help readers understand the application of the methods in greater depth. The book includes numerous comments and remarks providing insight and fundamental understanding into the modeling and control of batch processes. Modeling and Control of Batch Processes includes many detailed examples of industrial relevance that can be tailored by process control engineers or researchers to a specific application. The book is also of interest to graduate students studying control systems, as it contains new research topics and references to significant recent work. Advances in Industrial Control reports and encourages the transfer of technology in control engineering. The rapid development of control technology has an impact on all areas of the control discipline. The series offers an opportunity for researchers to present an extended exposition of new work in all aspects of industrial control.
Author: Gintaras V. Reklaitis Publisher: Springer Science & Business Media ISBN: 3642609724 Category : Science Languages : en Pages : 886
Book Description
Batch chemical processing has in the past decade enjoyed a return to respectability as a valuable, effective, and often preferred mode of process operation. This book provides the first comprehensive and authoritative coverage that reviews the state of the art development in the field of batch chemical systems engineering, applications in various chemical industries, current practice in different parts of the world, and future technical challenges. Developments in enabling computing technologies such as simulation, mathematical programming, knowledge based systems, and prognosis of how these developments would impact future progress in the batch domain are covered. Design issues for complex unit processes and batch plants as well as operational issues such as control and scheduling are also addressed.
Author: Iqbal M. Mujtaba Publisher: Elsevier ISBN: 0128137916 Category : Science Languages : en Pages : 662
Book Description
Desalination Technologies: Design and Operation sets the scene for desalination technologies as a long-term solution to freshwater demand by analyzing the current demand for water, available water resources and future predicted demand. The book captures recent developments in thermal desalination (multistage flash desalination, multi-effect evaporation, vapor compression), membrane desalination (forward osmosis, reverse osmosis, pressure retarded, electrodialysis, membrane distillation, ultra-, nano-, and micro-filtration), and alternative processes such as freezing and ion exchange. Both dynamic and steady state models (from short cut, simple, to detail) of various desalination processes are discussed. The book is intended for (under)graduate students in chemical engineering and postgraduate researchers and industrial practitioners in desalination. Provides the fundamentals of different desalination processes Includes desalination modeling from short and simple, to detailed and more advanced Discusses desalination optimization and synthesis to reduce environmental impact Handles thermo-physical property models and correlations Includes case studies to give a clearer understanding of desalination
Author: Sohrab Rohani Publisher: Butterworth-Heinemann ISBN: 0081012241 Category : Technology & Engineering Languages : en Pages : 630
Book Description
Coulson and Richardson’s Chemical Engineering: Volume 3B: Process Control, Fourth Edition, covers reactor design, flow modeling, and gas-liquid and gas-solid reactions and reactors. Converted from textbooks into fully revised reference material Content ranges from foundational through to technical Added emerging applications, numerical methods and computational tools
Author: C. McGreavy Publisher: Elsevier ISBN: 1483298906 Category : Technology & Engineering Languages : en Pages : 343
Book Description
Presents the latest results of both academic and industrial research in the control, modelling and dynamics of two of the most fundamental constituents of all chemical engineering plant. Includes contributions on fixed-bed, gas-phase and tubular reactors, thermal cracking furnaces and distillation columns, related to applications in all major areas of chemical engineering, including petrochemicals and bulk chemical manufacture. Contains 51 papers.
Author: W. H. B. W. Ibrahim
Author: W. H. B. W. Ibrahim
Author: R. Paulen
Author: Iván-Dario Gil
Author: Joseph Schork
Author: Prashant Mhaskar
Author: Dwayne L. Tyner
Author: Gintaras V. Reklaitis
Author: Iqbal M. Mujtaba
Author: Sohrab Rohani
Author: C. McGreavy