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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

THE DEVELOPMENT OF A METAL PLATE TEST REACTOR FOR STUDYING REACTION KINETICS ON CATALYTICALLY COATED HEAT TRANSFER COMPONENTS

KHOSRAVI, AIDA 28 September 2012 (has links)
A novel catalytic metal plate test reactor was designed, built and commissioned. The overall dimensions of the whole assembly were 215 mm long 75 mm wide 60 mm deep. A strip of stainless steel with dimensions of 150 mm long 15 mm wide 1.59 mm thick was partly coated with catalyst and sealed between the two reactor parts. The design provided a single channel flow pattern that could be easily modeled to extract kinetic parameters. A key feature of the reactor design was effective heat transfer to promote isothermal operation. A series of thermocouples was incorporated into the reactor to measure the temperature profile along the reactor. Performance of the reactor was verified using a well characterized commercially available Cu/Zn/Al2O3 catalyst from BASF. The goal of this experimentation was to determine the conversion, rate constant and activation energy for methanol steam reforming and compare these with previously published measurements. Methanol conversion was measured at slightly higher than atmospheric pressure at temperatures of 220, 240 and 260 °C. Steam to water ratio of feed was maintained at one during the experimental program. The feed rate of methanol was varied to obtain a catalyst to feed ratio between 6 and 20 kgs mol-1. The composition of reformate and methanol conversion were studied with temperature and flow rate of the feed. An increase from 27.68 to 41.61% in methanol conversion was observed increasing the reaction temperature from 220 to 240°C. An irreversible first order rate constant was calculated using the experimentally measured conversion and space time. The apparent activation energy (Ea) based on a first order plug flow design operation was 96±4 k.J.mol-1 and agreed well with the values of 77-105.1 kJmol-1 reported in the literature. / Thesis (Master, Chemical Engineering) -- Queen's University, 2012-09-28 12:39:38.392
2

Modélisation des échangeurs-réacteurs compacts / Compact heat exchanger reactor modelling

Barbé, Jean-Patrick 05 September 2018 (has links)
Le contexte industriel est favorable aux échangeurs-réacteurs catalytiques intensifiés puisqu’ils permettent une diminution des limitations aux transferts de matière et de chaleur comparé aux réacteurs conventionnels. Toutefois, l'industrialisation de ces unités est problématique à cause de l'absence de logiciel d’ingénierie de prédiction et d’optimisation de leurs performances. Afin de construire un tel outil, les écoulements, les transferts de matière interne et externe liés aux réactions catalytiques hétérogènes, les transferts de chaleur convectif, conductif, diffusif et par rayonnement sont d’abord analysés, permettant de formuler des hypothèses simplificatrices. Les phénomènes pertinents identifiés sont ensuite mis en équations pour créer la base physique de ProSec Réaction, le nouveau logiciel de simulation des échangeurs-réacteurs. Ce logiciel est validé par comparaison avec les résultats expérimentaux du pilote de vaporeformage du méthane d'Air Liquide et par confrontation avec des simulations tri-dimensionnelles de celui-ci (CFD). L'excellente adéquation entre les résultats expérimentaux et numériques démontre le potentiel de prédiction du modèle mono-dimensionnel développé. Dans le cas particulier des échangeurs-réacteurs à plaques et ailettes catalytiques (wash-coat), une représentation bi-dimensionnelle discrète est construite et permet de tenir compte des effets thermiques radiaux intrinsèques à ces échangeurs particuliers. Enfin, ProSec Réaction est exploité pour évaluer les perspectives d'optimisation géométrique des canaux de l'échangeur-réacteur du pilote d'Air Liquide. Celles-ci montrent la flexibilité et l'intérêt de ce nouvel outil de simulation / Intensified heat exchanger reactors are promising technologies in the current industrial context because of their high potential to significantly reduce heat and mass transfer limitations compared to conventional reactors. However, the absence of simulation software for predicting their performances and optimising their geometry inside a flowsheet is limiting the industrialisation of these units. Preliminary to the development of such a simulation tool, flow characteristics, internal and external mass transfers inherent to heterogeneous catalytic reactions, convective, conductive, diffusive and radiative heat transfers are analysed, allowing the definition of simplifying assumptions. The identified relevant phenomena are then modelled and constitute the physical base of ProSec Reaction, the new heat exchanger-reactor simulation software. This software is validated by comparing the predicted values to the Air Liquide steam reforming pilot plant results and to three-dimensional simulation results as well (CFD). The excellent consistency between numerical and experimental results demonstrates the accuracy and the predictive potential of the developed one-dimensional model. In the specific case of wall-coated plate-fin heat exchanger reactors, a discrete two-dimensional model is built and allows the representation of radial temperature gradients in the material, which are intrinsic to these specific heat exchangers. Finally, optimisation perspectives of the Air Liquide pilot plant heat exchanger reactor channel geometry are evaluated thanks to ProSec Reaction. They demonstrate the flexibility and the benefits of this new simulation tool

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