Review on Advanced Control Technique in Batch Polymerization Reactor of Styrene

Polymerization process have a nonlinear nature since it exhibits a dynamic behavior throughout the process. Therefore, accurate modeling and control technique for the nonlinear process needs to be obtained

Dynamic Modelling and Simulation of Non Isothermal Reactors

Reactors that operate in industrial plants are non-isothermal and thus, complex dynamic nature is expected. In order to design controllers with improved control performance, there is a need to study the dynamic behaviour of non-isothermal reactors. Dynamic modelling through mathematical modelling (which involves equations of physical and chemical laws) was conducted in this research. Polymerization reactors were the focus in this research which largely relied on the model and data taken from literature. Polymerization reactor is difficult to control due to its complicated reaction mechanism. To study its dynamic characteristics, the Melt Index of the produced polymer is controlled by manipulating the feed rates of hydrogen, FinyH2,in. This step has yielded the understanding that the quality of the polymer materials must be regulated to obtain the desired product. The steady state gain, K is developed from the transfer function model study. Steady state gain, K increases with the step changes in feed rates of hydrogen. The outcome of the study on K indicates the polymerization reactor has non-linear behaviour

Generalized multi-scale control scheme for cascade processes with time-delays

The cascade control is a well-known technique in process industry to improve regulatory control performance. The use of the conventional PI/PID controllers has often been found to be ineffective for cascade processes with long time-delays. Recent literature report has shown that the multi-scale control (MSC) scheme is capable of providing improved performance over the conventional PID controllers for processes characterized by long time-delays as well as slow RHP zeros. This paper presents an extension of this basic MSC scheme to cascade processes with long time-delays. This new cascade MSC scheme is applicable to self-regulating, integrating and unstable processes. Extensive numerical studies demonstrate the effectiveness of the cascade MSC scheme compared with some well-established cascade control strategies

Batch reactor design for polystyrene production

Kimya proseslerde sıvı akışı, kütle transferi ve ayırma işlemleri gibi fiziksel işlemler çok büyük bir rol oynar. Bununla birlikte, kimyasal bir değişimin meydana geldiği herhangi bir üretim işleminde, kimyasal reaktör üretimin kalbini oluşturur. Bu çalışmada, polistiren(PS) üretimi için kullanılacak kesikli reaktör tasarımı açıklanmaktadır. Süspansiyon polimerizasyonu, PS üretimi için en çok tercih edilen metottur. Süspansiyon polimerizasyonunda, reaksiyondan elde edilen parçacık boyutu çok önemlidir. Karıştırma hızı, karıştırıcı şekli, reaktör boyutu ve reaktör geometrisi, reaksiyon sıcaklığı ve basıncı gibi parametreler parçacık boyutunu etkilemektedir. Ayrıca, süspansiyon reaksiyonu ekzotermik bir reaksiyon olduğu için, reaksiyon sırasında sıcaklık ve basınç zamanla artar. Bu durum reaksiyonu olumsuz yönde etkiler. Bu nedenle, reaksiyon sabit bir basınç ve sıcaklıkta gerçekleştirilmelidir. Bu durum ve gerekli parametreler dikkate alınarak bir kesikli reaktör tasarımı yapılmıştır.Physical processes such as liquid flow, mass transfer and separation processes play a major role in chemical processes.However, in any production process where a chemical change occurs, the chemical reactor forms the heart of production. In this study, the design of batch reactor for polystyrene production is explained. Suspension polymerization is the most preferred method for PS production. In suspension polymerization, the particle size obtained from the reaction is very important. Parameters such as mixing speed, agitator shape, reactor size and reactor geometry, reaction temperature and pressure affect particle size. Furthermore, since the suspension reaction is an exothermic reaction, the temperature and pressure increase during the reaction over time. This adversely affects the reaction. Therefore, the reaction should be carried out at a constant pressure and temperature. A batch reactor was designed considering this situation and the required parameters

Molecular Weight Distributions in Ideal Polymerization Reactors. An Introductory Review

The ultimate aim of polymerization reaction engineering is the production of polymers with tailor-made properties. An introductory review into this field is presented, with emphasis on the effects on the molar mass distribution (MMD), of the sought combination of polymerization mechanism, reactor type, and reactor control. Three ideal polymerization mechanisms are analyzed: free-radical, living anionic, and step-growth. Living anionic and step-growth polymerizations are similar in that their growing chains remain reactive while inside the reactor; and for these systems the narrowest MMDs are produced in reactors with narrow residence time distributions (RDT); i.e.: batch or continuous tubularreactors. In contrast, in conventional free-radical polymerizations, the polymer molecules grow in a fraction of a second and thereafter remain inactive while inside the reactor. In this case, the RTD does not affect the MMD, and the homogeneous continuous stirred-tank reactors provide the narrowest MMDs. Representative mathematical models of polymerization reactors are useful for: a) quantifying the interrelationships between their numerous inputs and outputs; and b) developing open- and closedloop strategies for increasing reactor productivity and product quality.Fil: Meira, Gregorio Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina. Universidad Nacional del Litoral; ArgentinaFil: Oliva, H.. Universidad del Zulia; Venezuel

Dynamic Modelling and Simulation of Non Isothermal Reactors

Reactors that operate in industrial plants are non-isothermal and thus, complex dynamic nature is expected. In order to design controllers with improved control performance, there is a need to study the dynamic behaviour of non-isothermal reactors. Dynamic modelling through mathematical modelling (which involves equations of physical and chemical laws) was conducted in this research. Polymerization reactors were the focus in this research which largely relied on the model and data taken from literature. Polymerization reactor is difficult to control due to its complicated reaction mechanism. To study its dynamic characteristics, the Melt Index of the produced polymer is controlled by manipulating the feed rates of hydrogen, FinyH2,in. This step has yielded the understanding that the quality of the polymer materials must be regulated to obtain the desired product. The steady state gain, K is developed from the transfer function model study. Steady state gain, K increases with the step changes in feed rates of hydrogen. The outcome of the study on K indicates the polymerization reactor has non-linear behaviour

Optimization and control of a continuous polymerization reactor

This work studies the optimization and control of a styrene polymerization reactor. The proposed strategy deals with the case where, because of market conditions and equipment deterioration, the optimal operating point of the continuous reactor is modified significantly along the operation time and the control system has to search for this optimum point, besides keeping the reactor system stable at any possible point. The approach considered here consists of three layers: the Real Time Optimization (RTO), the Model Predictive Control (MPC) and a Target Calculation (TC) that coordinates the communication between the two other layers and guarantees the stability of the whole structure. The proposed algorithm is simulated with the phenomenological model of a styrene polymerization reactor, which has been widely used as a benchmark for process control. The complete optimization structure for the styrene process including disturbances rejection is developed. The simulation results show the robustness of the proposed strategy and the capability to deal with disturbances while the economic objective is optimized

On-line polymerisation monitoring in scCO2: a reliable and inexpensive sampling method in high pressure applications

A versatile and reliable on-line sampling system for polymerisation reactions in supercritical fluids was developed. By withdrawing a small volume of a high-pressure reaction mixture and expanding it in a controlled volume, reliable kinetic data were obtained for a range of reactions in scCO2, avoiding the need for costly equipment or setup modifications. All experiments were carried out in a stainless-steel high-pressure autoclave with mechanical stirring and a volume of 60 ml. With the polymerisation of methyl methacrylate (MMA) in scCO2 being widely adopted for research in the past, the free-radical and RAFT controlled dispersion polymerisations of MMA were analysed in detail using the sampling system as a proof-of-concept. Additionally, initial implementation of the sampling system to a range of different reactions showed the facile applicability of the monitoring method