Development Of A Software For Simulation Analysis Of The Phenomenon Of Phase Change Of Three-phase Catalytic Slurry Reactor

This work deals with the development of a software capable to simulate via deterministic modelling the phenomenon of phase change observed in three-phase catalytic slurry reactors, that occurs in the reacting medium and in the refrigerant fluid. The software is based on a detailed dynamic model formulation and considers different tools to evaluate the phase change. The developed software allows the simulation of different possibilities introduced in the model, aiming a better reproduction of chemical plant data. © 2004 Elsevier B.V. All rights reserved.18C703708Hanika, J., K, S., V, R., Hrstka, J., Measurement of axial temperature profiles in an adiabatic trickle-bed reactor (1976) Chem Eng. J., 12, p. 193Hichri, H., Armand, A., Andrieu, J., Kinetics and Slurry-type Reactor Modelling during Catalytic Hydrogenation of o-Cresol on Ni/SiO2 (1991) Chem. Eng. Proc., 30, pp. 133-140Incropera, F.P., de Witt, D.P., (1990) Fundamentals of Heat and Mass Transfer, p. 919. , John Wiley & SonsSalmi, T., Wärna, J., Toppinen, S., Ronnholm, M., Mikkola, J.P., Dynamic Modelling of Catalytic Three-Phase Reactors for Hydrogenation and Oxidation Processes (2000) Brazilian Journal of Chem. Eng., 17 (4-7), pp. 1023-1034Stephan, K., (1992) Heat Transfer in Condensation and Boiling, , Springer, New YorkVasco de Toledo, E.C., Wolf Maciel, M.R., Maciel Filho, R., Dynamic Modelling of a Three-Phase Catalytic Slurry Reactor (2001) Chem. Eng. Sci., 56, pp. 6055-6061Vasco de Toledo, E.C., Maciel Filho, R., Development of a Dynamic Model for a Three-Phase Catalytic Slurry Reactor with Change of Phase of the Reacting Medium and the Cooling Fluid (2002) 17th International Symposium on Chemical Reaction Engineering, ISCRE 17, , August 25-28, Hong Kong, ChinaVilladsen, J., Michelsen, M.L., (1978) Solution of Differential Equation Models by Polynomial Approximation, , Prentice-Hall, New Yor

Aperfeiçoamento tecnologico do processo de crioconcentração : modelagem e simulação

Orientadores: Maria Regina Wolf Maciel, Antonio Jose A. MeirellesTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia QuimicaResumo: Separação de misturas por cristalização tem sido usado por muitos anos. A remoção de água por cristalização e a, subseqüente, separação do gelo do líquido concentrado é chamada de crioconcentração, qualquer que seja o sistema considerado. Recentemente, porém, a aplicação de certos produtos químicos e bioquímicos utilizados na indústria farmacêutica e de alimentos, ou na produção de polímeros de alto-desempenho fizeram aumentar o interesse no estudo da cristalização. Somando-se a isso, tem-se as restrições impostas por leis ambientais, que requerem cada vez mais processos com tecnologias limpas. No esforço de se obter um modelo teórico para cristalização, esse processo de separação é associado, na presente tese, ao problema de Stefan (1889). Usualmente, o problema de Stefan é utilizado para modelar a cristalização de sólidos fundidos, em que a difusão de calor é o principal fenômeno. No presente trabalho, o problema de Stefan foi resolvido para uma situação em que a transferência de massa é o principal fenômeno, comumente chamada de cristalização de solução. Vale apenas salientar que esta solução é inédita na literatrura. O presente trabalho de tese está concentrada no desenvolvimento de um modelo unidimensional para cristalização de uma solução binária ou pseudo-binária. O problema foi resolvido e resultados típicos são apresentados sob várias condições. Observa-se que a expressão para a velocidade de crescimento do cristal concorda qualitativamente e quantitativamente, em alguns casos, com dados reportados na literatura. Em seguida, foi desenvolvida uma expressão teórica para o coeficiente de transferência de massa para sistemas em cristalização, baseado na condição de Stefan. Observa-se que o mesmo apresenta valores finitos, mesmo quando a espessura da camada limite tende a zero, indicando que é possível explicar o crescimento de cristais em solução, apenas com o fenômeno difusional. Na última parte da tese, a expressão da velocidade de crescimento do cristal, desenvolvida na presente tese, é aplicada ao estudo do regime dinâmico, do estado estacionário e à distribuição dos momentos de um cristalizador contínuo tipo MSMPR (Mixed Suepension, Mixed Producto Remova_. As equações foram resolvidas e uma extensa análise foi feita. Esses resultados podem ser aplicados no desenvolvimento de projetos de cristalizadores contínuos tipo MSMPRAbstract: Separation of mixtures by crystallization has been used for many years. Recently, however, the advent of certain chemical and biochemical specialties used in pharmaceutical and in food industries, or in the production of high-performance polymers, among other processes, as well as new constraints, such as environmental laws and increased economical competition, have expanded the interest in the crystallization studies, from both practical and theoretical points of view. As an effort for obtaining a theoretical model for the crystallization, this separation process is associated, in the present work, to the Stefan problem. The first work that can be associated to the mathematical problem of moving boundary is that proposed by Clapeyron and Lamé. Usually, the Stefan problem is associated to the crystallization of melted solids, in which the heat diffusion (or energy transfer) is the main phenomenon In the present work, the Stefan problem was solved for a situation in which the mass transfer is the most important phenomenon, namely the crystallization of solutions The present investigation is concerned with the development of a one-dimensional model for the crystallization of a binary or a pseudo-binary solution. The one-dimensional model is viewed as an appropriate starting point for due to its relatively simple approach, making possible the achievment of an analytical solution of the differential equation describing the process, so that the results are exact and easily interpreted. Results for a typical system are presented under various conditions and it is observed that the expression for the crystal growth agrees qualitatively well with experimental data reported in the literature. After that, it was developed one expression for mass transfer coefficient of the crystallization of the solution based in Stefan problem. Important results are obtained from the model, such an as: a finite coefficient of mass transfer is obtained wenh the thickness of the layer vanishes. In the last part of the thesis, the expression of the crystal growth rates is applied to the study of the stationary and dynamic steady state of a crystallizer MSMPR. These results can be applied in the development of designs of continuous crystallizers type MSMPRDoutoradoDesenvolvimento de Processos QuímicosDoutor em Engenharia Químic

Development Of Rigorous And Reduced Heterogeneous Dynamic Models For Fixed Bed Catalytic Reactor And Three-phase Catalytic Slurry Reactor

In this work, the dynamic behavior of two chemical reactors (Fixed Bed Catalytic Reactor and the Three-Phase Reactor), in which different reactions of great industrial interest take place, is presented. Rigorous and reduced models were developed and their capabilities to adequately predict the dynamic behavior of these reactors were compared, indicating which model is more suitable for a specific application (design, optimization and control). Different approaches [Classic, Hermite, Finlayson, Pirkle, Dixion, Generic and Orthogonal collocation (one point)] were used to obtain the reduced models. With these techniques, a mathematical order reduction was carried out, which eliminates the spatial co-ordinate (of the catalyst particle or of the reactor) and promotes radially lumped-differential formulations. The proposed rigorous models were able to predict the main characteristics of the dynamic behavior of the fixed bed catalytic reactor as well as of the three-phase reactor, including the inverse response phenomena and the hot spot present in the former. This knowledge is essential to design and control these reactors. The computational time demanded for the solution of the rigorous models is high in comparison to the reduced ones, which restricts the use of the rigorous models to cases where time is not a limiting factor. Otherwise, when on-line applications are required, the reduced models are more adequate. The models based on reduction techniques overcame computational burden with a faster and easier numerical solution, as well as other difficulties found in rigorous heterogeneous models, especially related to the large number of parameters and sophisticated numerical procedures required by the solution. © 2008 Berkeley Electronic Press. All rights reserved.31Bergault, I., Rajashekharam, M.V., Chaudhari, R.V., Schweich, D., Delmas, H., Modeling and comparison of acetophenone hydrogenation in trickle-bed and slurry airlift reactors (1997) Chem. Eng. Sci., 52 (21-22), pp. 4033-4043Biardi, G., Baldi, G., Three-phase catalytic reactors Catalysis Today, 52, pp. 223-234Corrêa, E.J., Cotta, R.M., Improved lumped-differential formulations of transient heat conduction problems (1999) III Congress of Mechanical Engineering on North-Northeast, , PA, Brazil 1994Coussemant, F., Jungers, J.C., Cinétique de ĺHydrogénation Catalytique des Phénols (1950) Bull. Sec. Chim. 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Sci., 26, pp. 1081-1091Froment, G.H., Bischoff, K.B., (1990) Chemical Reactor Analysis and Design, , 2th ed., John Wiley & Sons, New YorkGianetto, A., Silveston, P.L., (1986) Multiphase Chemical Reactors: Theory, Design, Scale-up, , Washington: Hemisphere Publishing CorporationHahn, J., Edgar, T.F., Balancing approach to minimal realization and model reduction of stable nonlinear systems (2002) Ind. Eng. Chem. Res., 41, pp. 2204-2212Julcour, C., Stüber, F., Le Lann, J.M., Wilhelm, A.M., Delmas, H., Dynamics of a three-phase upflow fixed-bed catalytic reactor (1999) Chem. Eng. Sci., 54, pp. 2391-2400Jutan, A., Tremblay, J.P., McGregor, J.F., Wright, J.D., Multivariable computer control of a butane hydrogenolysis reactor: Part i state space reactor modelling (1977) AIChE Journal, 23 (5), pp. 732-742Löffler, H.-P., Marquardt, W., Order reduction of nonlinear differential-algebraic process models (1991) J. Proc. Control, 32, pp. 1546-1551Lange, R., Gutsche, R., Hanika, J., Forced periodic of a trickle-bed reactor (1999) Chem. Eng. Sci., 54, pp. 2569-2573MacIel Filho, R., (1989) Modelling and Control of Multitubular Reactors, , Ph.D. Thesis, University of Leeds, LeedsMariano, A.P., Vasco De Toledo, E.V., Silva, J.M.F., Wolf MacIel, M.R., MacIel Filho, R., Development of a software for simulation analysis of the phenomenon of phase change of three-phase catalytic slurry reactor (2005) Comp. Chem. Eng., 29, pp. 1369-1378Marquard, W., Nonlinear model reduction for optimization based control of transient chemical processes (2002) Proceedings of the 6th International Conference of Chemical Process Control, AIChe Symp. Ser., 326 (98), p. 12Martinez, O.M., Pereira Duarte, S.J., Lemcoff, N.O., Modeling of fixed bed catalytic reactors (1985) Comp. Chem. Eng., 9 (5), pp. 535-545McGreavy, C., On-line computer system for chemical reactor processes (1983) Comp. Chem. Eng., 7 (4), pp. 529-566McGreavy, C., MacIel Filho, R., Dynamic behavior of fixed bed catalytic reactors (1989) IFAC Dynamics and Control of Chemical Reactors, , Maastricht, The NetherlandsPellegrini, L., Biardi, G., Ranzi, E., Dynamic model of packed-bed tubular reactors (1989) Comp. Chem. Eng., 13 (4-5), pp. 511-518Pirkle Jr., J.C., Reyes, S.C., Hagan, P.S., Khesghi, H., Solution of dynamic distributed parameter model of nonadiabatic, fixed-bed reactor (1987) Comp. Chem. Eng., 11 (6), pp. 737-747Ramachandran, P.A., Chaudhari, R.V., (1983) Three-Phase Catalytic Reactors, , Gordon and Breach Science Publisher, New YorkSalmi, T., Wärna, J., Toppinen, S., Rönnholm, M., Mikkola, J.P., Dynamic modelling of catalytic three-phase reactors for hydrogenation and oxidation Processes (2000) Braz J. of Chem. Eng., 17 (4-7), pp. 1023-1034Santana, P.L., (1995) Mathematical Models for Three-Phase Slurry Reactors Applied to Hydrogenation of O-Cresol, , MSc. Thesis, UNICAMP, Campinas, SP, BrazilSantana, P.L., (1999) Mathematical Modelling for A Three-Phase Reactor: Deterministic, , Neural and Hybrid Models PhD. Thesis, UNICAMP, Campinas, SP, BrazilShah, Y.T., (1979) Gas-Liquid-Solid Reactor Design, , McGraw-Hill Inc New YorkSun, C., Hahn, J., Model reduction in the presence of uncertainty in model parameters (2006) J. Proc. Control, 16, pp. 645-649Van Den Bergh, J., (2005) Model Reduction for Dynamic Real-Time Optimization of Chemical Processes, , PhD Thesis Delft University of Technology, The NetherlandsVasco De Toledo, E.C., (1999) Modelling, Simulation and Control of the Fixed Bed Catalytic Reactors, , Ph.D. Thesis, University of Campinas, São Paulo, BrazilVasco De Toledo, E.C., Santana, P.L., Wolf MacIel, M.R., MacIel Filho, R., Dynamic modelling of a three-phase catalytic slurry reactor (2001) Chem. Eng. Sci., 00215, 56 (21-22)Vasco De Toledo, E.C., MacIel Filho, R., Development of a dynamic model for a three-phase catalytic slurry reactor with change of phase of the reacting medium and the cooling fluid (2002) 17th International Symposium on Chemical Reaction Engineering, ISCRE 17, , August 25-28, Hong Kong, ChinaVilladsen, J., Michelsen, M.L., (1978) Solution of Differential Equation Models by Polynomial Approximation, , Prentice-Hall New Jerse