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An algorithm for stabilizing unstable steady states for jacketed nonisothermal continually stirred tank reactors / Farouq S. Mjalli in Industrial & engineering chemistry research, Vol. 48 N° 16 (Août 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 16 (Août 2009) . - pp. 7631–7636 Titre : An algorithm for stabilizing unstable steady states for jacketed nonisothermal continually stirred tank reactors Type de document : texte imprimé Auteurs : Farouq S. Mjalli, Auteur ; N. S. Jayakumar, Auteur Année de publication : 2009 Article en page(s) : pp. 7631–7636 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Continually  stirred  tank  reactors  Steady  states  Cooling  jacket Résumé : The operation of nonisothermal jacketed continually stirred tank reactors (CSTRs) involves a high degree of nonlinearity, and for certain operating conditions this nonlinearity may cause concentration multiplicity at steady state. At these conditions, certain steady states will be unstable and difficult to observe and maintain. The dynamics of the cooling jacket has a profound effect on these conditions and hence should be taken into consideration for the proper reactor design. A novel steady-state design algorithm is presented here to stabilize the CSTR at such conditions. This is achieved by replacing the single CSTR by a cascade of reactors that are capable of stabilizing and maintaining the unstable steady state. The new design approach implements an optimization of the reactors operating parameters to achieve this solution. The implementation of the solution algorithm is shown graphically and also shown is the use of numerical computational optimization solution techniques. For a first order reaction, both solutions were successful at achieving the unstable steady state; however, the numerical solution was more accurate. Simulations of the new design showed that the reactors’ cascades were capable of stabilizing the metastable temperature to a high degree of accuracy. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900072g [article] An algorithm for stabilizing unstable steady states for jacketed nonisothermal continually stirred tank reactors [texte imprimé] / Farouq S. Mjalli, Auteur ; N. S. Jayakumar, Auteur . - 2009 . - pp. 7631–7636. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 16 (Août 2009) . - pp. 7631–7636 Mots-clés : Continually  stirred  tank  reactors  Steady  states  Cooling  jacket Résumé : The operation of nonisothermal jacketed continually stirred tank reactors (CSTRs) involves a high degree of nonlinearity, and for certain operating conditions this nonlinearity may cause concentration multiplicity at steady state. At these conditions, certain steady states will be unstable and difficult to observe and maintain. The dynamics of the cooling jacket has a profound effect on these conditions and hence should be taken into consideration for the proper reactor design. A novel steady-state design algorithm is presented here to stabilize the CSTR at such conditions. This is achieved by replacing the single CSTR by a cascade of reactors that are capable of stabilizing and maintaining the unstable steady state. The new design approach implements an optimization of the reactors operating parameters to achieve this solution. The implementation of the solution algorithm is shown graphically and also shown is the use of numerical computational optimization solution techniques. For a first order reaction, both solutions were successful at achieving the unstable steady state; however, the numerical solution was more accurate. Simulations of the new design showed that the reactors’ cascades were capable of stabilizing the metastable temperature to a high degree of accuracy. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900072g

Approximate predictive versus self-tuning adaptive control strategies of biodiesel reactors / Farouq S. Mjalli in Industrial & engineering chemistry research, Vol. 48 N° 24 (Décembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 11034–11047 Titre : Approximate predictive versus self-tuning adaptive control strategies of biodiesel reactors Type de document : texte imprimé Auteurs : Farouq S. Mjalli, Auteur ; Mohamed Azlan Hussain, Auteur Année de publication : 2010 Article en page(s) : pp. 11034–11047 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Approximate--Predictive--versus--Self-Tuning--Adaptive--Control--Strategies--Biodiesel--Reactors Résumé : Producing biodiesel from palm oil as a raw material involves complex transesterification reactions which add up to the process nonlinearity. In this work, more emphasis will be focused on the reactor nonlinearity and ways of solving its control problem. The reactor nonlinearity is addressed via the application of an instantaneous linearization technique to control the reactor temperature and the triglyceride product concentration. A feed-forward neural network with delayed inputs and outputs was trained and validated to capture the dynamics of the biodiesel process. The generated nonlinear model was then utilized in an instantaneous linearization algorithm using two control algorithms adopting the self-tuning adaptive control and an approximate model predictive framework. The two algorithms were compared in terms of set-point tracking capability, efficiency, and stability. The minimum variance control algorithm attained poor performance compared to the pole-placement self-tuning adaptive algorithm. However, the approximate model predictive control strategy was superior to the self-tuning control in terms of its ability for forcing the output to follow the set-point trajectory efficiently with smooth controller moves. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900930k [article] Approximate predictive versus self-tuning adaptive control strategies of biodiesel reactors [texte imprimé] / Farouq S. Mjalli, Auteur ; Mohamed Azlan Hussain, Auteur . - 2010 . - pp. 11034–11047. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 11034–11047 Mots-clés : Approximate--Predictive--versus--Self-Tuning--Adaptive--Control--Strategies--Biodiesel--Reactors Résumé : Producing biodiesel from palm oil as a raw material involves complex transesterification reactions which add up to the process nonlinearity. In this work, more emphasis will be focused on the reactor nonlinearity and ways of solving its control problem. The reactor nonlinearity is addressed via the application of an instantaneous linearization technique to control the reactor temperature and the triglyceride product concentration. A feed-forward neural network with delayed inputs and outputs was trained and validated to capture the dynamics of the biodiesel process. The generated nonlinear model was then utilized in an instantaneous linearization algorithm using two control algorithms adopting the self-tuning adaptive control and an approximate model predictive framework. The two algorithms were compared in terms of set-point tracking capability, efficiency, and stability. The minimum variance control algorithm attained poor performance compared to the pole-placement self-tuning adaptive algorithm. However, the approximate model predictive control strategy was superior to the self-tuning control in terms of its ability for forcing the output to follow the set-point trajectory efficiently with smooth controller moves. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900930k

Approximate predictive versus self-tuning adaptive control strategies of biodiesel reactors / Farouq S. Mjalli in Industrial & engineering chemistry research, Vol. 48 N° 24 (Décembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 11034–11047 Titre : Approximate predictive versus self-tuning adaptive control strategies of biodiesel reactors Type de document : texte imprimé Auteurs : Farouq S. Mjalli, Auteur ; Mohamed Azlan Hussain, Auteur Année de publication : 2010 Article en page(s) : pp. 11034–11047 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Palm  oil  Transesterification  reactions  Reactor  nonlinearity Résumé : Producing biodiesel from palm oil as a raw material involves complex transesterification reactions which add up to the process nonlinearity. In this work, more emphasis will be focused on the reactor nonlinearity and ways of solving its control problem. The reactor nonlinearity is addressed via the application of an instantaneous linearization technique to control the reactor temperature and the triglyceride product concentration. A feed-forward neural network with delayed inputs and outputs was trained and validated to capture the dynamics of the biodiesel process. The generated nonlinear model was then utilized in an instantaneous linearization algorithm using two control algorithms adopting the self-tuning adaptive control and an approximate model predictive framework. The two algorithms were compared in terms of set-point tracking capability, efficiency, and stability. The minimum variance control algorithm attained poor performance compared to the pole-placement self-tuning adaptive algorithm. However, the approximate model predictive control strategy was superior to the self-tuning control in terms of its ability for forcing the output to follow the set-point trajectory efficiently with smooth controller moves. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900930k [article] Approximate predictive versus self-tuning adaptive control strategies of biodiesel reactors [texte imprimé] / Farouq S. Mjalli, Auteur ; Mohamed Azlan Hussain, Auteur . - 2010 . - pp. 11034–11047. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 11034–11047 Mots-clés : Palm  oil  Transesterification  reactions  Reactor  nonlinearity Résumé : Producing biodiesel from palm oil as a raw material involves complex transesterification reactions which add up to the process nonlinearity. In this work, more emphasis will be focused on the reactor nonlinearity and ways of solving its control problem. The reactor nonlinearity is addressed via the application of an instantaneous linearization technique to control the reactor temperature and the triglyceride product concentration. A feed-forward neural network with delayed inputs and outputs was trained and validated to capture the dynamics of the biodiesel process. The generated nonlinear model was then utilized in an instantaneous linearization algorithm using two control algorithms adopting the self-tuning adaptive control and an approximate model predictive framework. The two algorithms were compared in terms of set-point tracking capability, efficiency, and stability. The minimum variance control algorithm attained poor performance compared to the pole-placement self-tuning adaptive algorithm. However, the approximate model predictive control strategy was superior to the self-tuning control in terms of its ability for forcing the output to follow the set-point trajectory efficiently with smooth controller moves. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900930k

Artificial neural approach for modeling the heat and mass transfer characteristics in three-phase fluidized beds / Farouq S. Mjalli in Industrial & engineering chemistry research, Vol. 47 N° 13 (Juillet 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4542–4552 Titre : Artificial neural approach for modeling the heat and mass transfer characteristics in three-phase fluidized beds Type de document : texte imprimé Auteurs : Farouq S. Mjalli, Auteur ; A. Al-Mfargi, Auteur Année de publication : 2008 Article en page(s) : p. 4542–4552 Note générale : Bibliogr. p. 4551-4552 Langues : Anglais (eng) Mots-clés : Fluidized  bed  three-phase  reactors;  Heat  transfer;  Mass  transfer;  Artificial  neural  network Résumé : The study of reactor design and modeling is conducted frequently both at the initial stage of equipment design as well as during further stages of equipment operation. Fluidized bed three-phase reactors have very complex behavior which relies to a high extent on the mass and heat transfer characteristics of the reaction constituents. Numerous previous experimental and theoretical based studies for modeling heat and mass transfer coefficients have the common shortcoming of low prediction efficiency compared to experimental data. In this work, an artificial neural network approach is used to capture the reactor characteristics in terms of heat and mass transfer based on published experimental data. The newly developed heat and mass transfer coefficients models proved to be of high prediction quality compared to experimental data and previous correlations. The new correlations will be used in a further study for the hybrid steady state and dynamic modeling of fluidized bed catalytic reactors. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0715714 [article] Artificial neural approach for modeling the heat and mass transfer characteristics in three-phase fluidized beds [texte imprimé] / Farouq S. Mjalli, Auteur ; A. Al-Mfargi, Auteur . - 2008 . - p. 4542–4552. Bibliogr. p. 4551-4552 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4542–4552 Mots-clés : Fluidized  bed  three-phase  reactors;  Heat  transfer;  Mass  transfer;  Artificial  neural  network Résumé : The study of reactor design and modeling is conducted frequently both at the initial stage of equipment design as well as during further stages of equipment operation. Fluidized bed three-phase reactors have very complex behavior which relies to a high extent on the mass and heat transfer characteristics of the reaction constituents. Numerous previous experimental and theoretical based studies for modeling heat and mass transfer coefficients have the common shortcoming of low prediction efficiency compared to experimental data. In this work, an artificial neural network approach is used to capture the reactor characteristics in terms of heat and mass transfer based on published experimental data. The newly developed heat and mass transfer coefficients models proved to be of high prediction quality compared to experimental data and previous correlations. The new correlations will be used in a further study for the hybrid steady state and dynamic modeling of fluidized bed catalytic reactors. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0715714

Generation of superoxide ion in pyridinium, morpholinium, ammonium, and sulfonium - based ionic liquids and the application in the destruction of toxic chlorinated phenols / Maan Hayyan in Industrial & engineering chemistry research, Vol. 51 N° 32 (Août 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 32 (Août 2012) . - pp. 10546-10556 Titre : Generation of superoxide ion in pyridinium, morpholinium, ammonium, and sulfonium - based ionic liquids and the application in the destruction of toxic chlorinated phenols Type de document : texte imprimé Auteurs : Maan Hayyan, Auteur ; Farouq S. Mjalli, Auteur ; Mohd Ali Hashim, Auteur Année de publication : 2012 Article en page(s) : pp. 10546-10556 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Ionic  liquid Résumé : Generation of superoxide ion (O2•―) was carried out in four ionic liquids (ILs) having the same anion, bis(trifluoromethylsulfonyl)imide [N(Tf)2]―, and different cations, N-hexylpyridinium [HPy]+, N-methoxyethyl-N-methyl-morpholinium [MO1,1O2]+, N-ethyl-N,N-dimethyl-2-methoxyethylammonium [N112,1O2]+, and triethylsulfonium [S222]+. Cyclic voltammetry (CV) and chronoamperometry (CA) electrochemical techniques were used in this investigation. It was found that O2•― is not stable in the [HPy]+-based IL. On the other hand, CV showed that the electrochemically generated O2•― is stable in [MO1,1O2]+-, [N112,1O2]+-, and [S222]+-based ILs for the time duration of the experiment. The long-term stability of the generated O2•― was then investigated by dissolving potassium superoxide (KO2) in dimethyl sulfoxide (DMSO) in the presence of the corresponding IL. It was found that ILs containing [MO1,1O2]+ and [N112,1O2]+ offer a promising long-term stability of O2•― for various reactions to be used for several applications. However, it was found that after 2 h, about 92.5% of the generated O2•― in [S222]+ based IL was consumed. The diffusion coefficient and solubility of O2 in the studied ILs were then determined using CV and CA techniques simultaneously. It was found that diffusion coefficients and CA steady-state currents increase with temperature increases, while the solubility of O2 decreased. To our best knowledge, this is the first time that morpholinium and sulfoniumbased ILs were utilized as media for chemical and electrochemical generation of O2•―. Additionally, the chemically generated O2•―, by dissolving KO2, was then used for the destruction of 2,4-dichlorophenol (DCP) in [MO1,1O2][N(Tf)2] under ambient conditions. The destruction percentage was higher than 98%. This work represents a novel application of the chemically generated O2•― for the destruction of toxic chlorinated phenols in ILs media. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26259758 [article] Generation of superoxide ion in pyridinium, morpholinium, ammonium, and sulfonium - based ionic liquids and the application in the destruction of toxic chlorinated phenols [texte imprimé] / Maan Hayyan, Auteur ; Farouq S. Mjalli, Auteur ; Mohd Ali Hashim, Auteur . - 2012 . - pp. 10546-10556. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 32 (Août 2012) . - pp. 10546-10556 Mots-clés : Ionic  liquid Résumé : Generation of superoxide ion (O2•―) was carried out in four ionic liquids (ILs) having the same anion, bis(trifluoromethylsulfonyl)imide [N(Tf)2]―, and different cations, N-hexylpyridinium [HPy]+, N-methoxyethyl-N-methyl-morpholinium [MO1,1O2]+, N-ethyl-N,N-dimethyl-2-methoxyethylammonium [N112,1O2]+, and triethylsulfonium [S222]+. Cyclic voltammetry (CV) and chronoamperometry (CA) electrochemical techniques were used in this investigation. It was found that O2•― is not stable in the [HPy]+-based IL. On the other hand, CV showed that the electrochemically generated O2•― is stable in [MO1,1O2]+-, [N112,1O2]+-, and [S222]+-based ILs for the time duration of the experiment. The long-term stability of the generated O2•― was then investigated by dissolving potassium superoxide (KO2) in dimethyl sulfoxide (DMSO) in the presence of the corresponding IL. It was found that ILs containing [MO1,1O2]+ and [N112,1O2]+ offer a promising long-term stability of O2•― for various reactions to be used for several applications. However, it was found that after 2 h, about 92.5% of the generated O2•― in [S222]+ based IL was consumed. The diffusion coefficient and solubility of O2 in the studied ILs were then determined using CV and CA techniques simultaneously. It was found that diffusion coefficients and CA steady-state currents increase with temperature increases, while the solubility of O2 decreased. To our best knowledge, this is the first time that morpholinium and sulfoniumbased ILs were utilized as media for chemical and electrochemical generation of O2•―. Additionally, the chemically generated O2•―, by dissolving KO2, was then used for the destruction of 2,4-dichlorophenol (DCP) in [MO1,1O2][N(Tf)2] under ambient conditions. The destruction percentage was higher than 98%. This work represents a novel application of the chemically generated O2•― for the destruction of toxic chlorinated phenols in ILs media. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26259758

Recursive least squares - based adaptive control of a biodiesel transesterification reactor / Ho Yong Kuen in Industrial & engineering chemistry research, Vol. 49 N° 22 (Novembre 2010) 

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