Home About us Contact
|
Home About us Contact | ||
|
|
||
Reactor Vessel (reactor + vessel)
Selected AbstractsReview on Mixing Characteristics in Solid-Liquid and Solid-Liquid-Gas Reactor VesselsTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2005Gopal R. Kasat Abstract Mechanically agitated reactors with single and multiple impeller systems are used in the industry for the various three-phase mixing processes such as crystallization, fermentation, and hydrogenation, etc. The paper reviews the experimental work reported in the literature along with different techniques used for the measurement of the specific quantities such as minimum or critical impeller speed for solid suspension. The work critically surveys the literature and makes specific recommendations for the use of appropriate correlations and conditions to be used for the success of such equipment. This assessment will put all the relevant literature on a common footing and will help to validate work reported earlier. Les réacteurs agités mécaniquement munis d'une seule turbine et de turbines multiples sont utilisés dans l'industrie pour divers procédés de mélange triphasiques, tels que la cristallisation, la fermentation, l'hydrogénation, etc. On examine dans cet article les travaux expérimentaux présentés dans la littérature scientifique ainsi que les différentes techniques utilisées pour la mesure de quantités spécifiques, telle la vitesse de turbine minimale ou critique pour la suspension de solides. On effectue une étude critique de la littérature scientifique et on propose des recommandations pour le choix de corrélations et conditions appropriées pour une bonne utilisation de cet équipement. Cette évaluation mettra toutes les publications pertinentes à un même niveau et aidera à valider le travail présenté antérieurement. [source] Enhancement of heat transfer in hydrogen storage tank with hydrogen absorbing alloy (optimum fin layout)HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 3 2008Yuichi Mitsutake Abstract Optimization of the fin layout in a metal hydride (MH) bed has been sought to enhance poor heat transmission in a hydrogen storage tank, and to obtain a maximum hydrogen absorption rate with a smaller volume of fins. Two different fin configurations, radial and circular fins, in a vertical cylindrical reactor vessel were tested with a La-Ni-based AB5 type hydrogen storage alloy. A two-dimensional transient heat conduction analysis, coupled with predicted temperature and concentration of absorbed hydrogen in the bed for the exothermic hydride reaction, was used to evaluate enhancement of the hydrogen absorption time. The estimated temperature and concentration agreed within 6 K and 8.5%, respectively, with our experimental results. The effect of thickness and the spacing and shape of fins on the hydrogen absorption time were analytically evaluated, so that the optimum range of the each fin layout was obtained by the trade off between absorption time and reduction in the MH volume due to the volume occupied by fins. The hydrogen absorption time for the recommended layout of circular fins was reduced to approximately one-third of that without fins. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(3): 165,183, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20195 [source] Identification and control of a riser-type FCC unitTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2001Abdul-Alghasim Alaradi Abstract This paper addresses the use of feedforward neural networks for the steady-state and dynamic identification and control of a riser type fluid catalytic cracking unit (FCCU). The results are compared with a conventional PI controller and a model predictive control (MPC) using a state space subspace identification algorithm. A back propagation algorithm with momentum term and adaptive learning rate is used for training the identification networks. The back propagation algorithm is also used for the neuro-control of the process. It is shown that for a noise-free system the adaptive neuro-controller and the MPC are capable of maintaining the riser temperature, the pressure difference between the reactor vessel and the regenerator, and the catalyst bed level in the reactor vessel, in the presence of set-point and disturbance changes. The MPC performs better than the neuro controller that in turn is superior to the conventional multi-loop diagonal PI controller. On examine dans cet article l'utilisation de réseaux neuronaux à anticipation pour la détermination et la régulation en régimes dynamique et permanent d'une unité de craquage catalytique de fluide de type colonne montante (FCCU). Un algorithme de rétro-propagation avec un terme de quantité de mouvement et une vitesse d'apprentissage adaptative est utilisé pour l'entraînement des réseaux d'identification. L'algorithme de rétro-propagation est également utilisé pour le controle neuronal du procédé. On montre que pour un système non bruité le contôleur neuronal adaptatif est capable de maintenir la température de colonne, la différence de pression entre le réacteur et le régénerateur ainsi que le niveau de lit de catalyseur dans le réacteur, en présence de changements dans les point de consigne et les perturbations. [source] Membrane bioreactors: overview of the effects of module geometry on mixing energyASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009Yuan Wang Abstract Membranes used in municipal membrane bioreactor (MBR) plants can be configured as flat sheet (FS) membranes or hollow fibre (HF) membranes. The HFs can be mounted either horizontally or vertically. The membranes can be immersed in their own vessel or within the aerobic vessel. These various configurations combine to give a unique reactor design. Current methods of design assume the mixing characteristics (e.g. each reactor vessel is completely mixed); hence the energy necessary to achieve complete mixing cannot be optimised. This paper presents an overview of mixing studies undertaken by the authors' research group on pilot- and full-scale MBRs through residence time distribution (RTD) analysis and computational fluid dynamics (CFD) modelling. The drawbacks of current technique for the sizing of MBRs (e.g. compartmental modelling) are highlighted. The use of CFD as a design tool to evaluate the mixing and energy of MBRs with different configurations (e.g. HF vs FS, inside submerged vs outside submerged) is presented. The MBR CFD model was validated using field-measured RTD data and compared with compartmental model. Results from mixing studies suggest that HF membranes are more energy efficient in terms of creating completely mixed conditions than the FS membranes. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Continuous Soluble Ziegler-Natta Ethylene Polymerizations in Reactor Trains, 3 , Influence of Operating Conditions upon Process PerformanceMACROMOLECULAR REACTION ENGINEERING, Issue 2 2008Marcelo Embiruçu Abstract The behavior of continuous solution ethylene/but-1-ene polymerizations through Ziegler-Natta catalysts is analyzed, based on a previously developed mathematical model. In order to do that, dynamic simulations are carried out and process responses are analyzed as functions of process operating policies and flowsheet configuration, at conditions that resemble the actual operation of industrial sites. It is shown that system responses are highly nonlinear and very sensitive to disturbances of the operating conditions and that catalyst decay is of fundamental importance for proper understanding of process behavior. Results indicate that mixing conditions inside the reactor vessels exert a significant impact upon the final polymer quality and can be manipulated for in-line control of final resin properties. Finally, it is shown that the development of feed policies, based on the use of lateral feed streams, allows the simultaneous control of melt flow index, stress exponent and polymer density of the final polymer resin. [source] | ||||||||||