Dissertations / Theses: 'Chemical reactors'

1

Srinivasan, Ravi 1971. "Microfabricated reactors for partial oxidation reactions." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9865.

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2

Coker, Akintunde K. "A study of fast reactions in nozzle type reactors." Thesis, Aston University, 1985. http://publications.aston.ac.uk/10181/.

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3

Lambert, Paul G. "Gas evolution in batch chemical reactors." Thesis, London South Bank University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618653.

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4

Seki, Hiroya. "Feedback Control of Nonlinear Chemical Reactors." 京都大学 (Kyoto University), 2002. http://hdl.handle.net/2433/149439.

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5

Rashid, Muhammad. "Stability and dynamic operability analysis of chemical processes." Title page, table of contents and abstract only, 1988. http://web4.library.adelaide.edu.au/theses/09ENS/09ensr224.pdf.

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6

Willis, Mark J. "Control of a class of chemical reactors." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315920.

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7

Dunckley, Christopher Paul. "Magnetic resonance chemical mapping of catalytic reactors." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612503.

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8

Sime, Nathan. "Numerical modelling of chemical vapour deposition reactors." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/36227/.

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In this thesis we study the chemical reactions and transport phenomena which occur in a microwave power assisted chemical vapour deposition (MPA-CVD) reactor which facilitates diamond growth. First we introduce a model of an underlying binary gas flow and its chemistry for a hydrogen gas mixture. This system is heated by incorporating a microwave frequency electric field, operating in a resonant mode in the CVD chamber. This heating facilitates the dissociation of hydrogen and the generation of a gas discharge plasma, a key component of carbon deposition in industrial diamond manufacture. We then proceed to summarise the discontinuous Galerkin (DG) finite element discretisation of the standard hyperbolic and elliptic partial differential operators which typically occur in conservation laws of continuum models. Additionally, we summarise the non-stabilised discontinuous Galerkin formulation of the time harmonic Maxwell operator. These schemes are then used as the basis for the discretisation method employed for the numerical approximation of the MPA-CVD model equations. The practical implementation of the resulting DG MPA-CVD model is an extremely challenging task, which is prone to human error. Thereby, we introduce a mathematical approach for the symbolic formulation and computation of the underlying finite element method, based on automatic code generation. We extend this idea further such that the DG finite element formulation is automatically computed following the user's specification of the convective and viscous flux terms of the underlying PDE system in this symbolic framework. We then devise a method for writing a library of automatically generated DG finite element formulations for a hierarchy of partial differential equations with automatic treatment of prescribed boundary conditions. This toolbox for automatically computing DG finite element solutions is then applied to the DG MPA-CVD model. In particular, we consider reactor designs inspired by the AIXTRON and LIMHP reactors which are analysed extensively in the literature.

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9

Samardzjia, Nikola. "Nonlinear analysis and control of chemical reactors." Thesis, University of Leeds, 1997. http://etheses.whiterose.ac.uk/728/.

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This thesis carries out a detailed study of a nonlinear spectral theory that is useful for modeling and controlling chemical reactors. The motivation for this work originates from a few reports which have demonstrated in the past that the nonlinear spectral method offers a useful mathematical framework for classifying and quantifying nonlinear complexities of large degrees of freedom, as well as for qualifying a general nonlinear dynamic behavior. We present and discuss this new theory and show that it extends the familiar linear systems notion of characteristic modes (eigenmodes), as well as the notions of mathematical quantities known as the eigenvectors, and eigenvalues, into a multi-dimensional nonlinear domain, i. e., applies to model dimensions one, two, three and higher. This approach offers a new insight into nonlinear phenomena, and as such has a significant theoretical and practical value. In the theory of nonlinear systems the spectral framework provides some useful answers regarding the issues of multivariate process complexity, stability and control. Similarly, in applications it often leads to a simple relation between a desired process behavior and control parameters. We demonstrate this by showing how a process operating point, its behavior, and its domain of attraction are determined by nonlinear structures which characterize both a process and its control realization. In addition, we show that by a correctly modeling and regulating process nonlinearities one can obtain a nonlinear control solution that often outperforms the conventional first-order realizations. That is, there exist important nonlinear structural and dynamic process relations which determine a feasibility of a control realization. This is demonstrated by studying control behaviors of several highly exothermic continuously stirred tank reactor processes.

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10

Conti, G. A. P. "Some aspects of process synthesis with emphasis on reactors and reactions." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234792.

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Two major, largely unknown, areas of process synthesis are explored in this dissertation, and procedures are proposed for the solving of problems within them. In each area, case studies are reported. The work on the first area results in the development of a general procedure for the efficient screening of alternative process routes. The procedure is applied to two examples of commodity chemicals: methyl methacrylate (MMA) and vinyl chloride monomer (VCM). By using suitable knowledge of organic chemistry, thermodynamics, kinetics, and costing, gradual screening of the process alternatives can be achieved from the earliest stages of conceptual design, with minimum calculation effort. The MMA example is concentrated on the selection of raw materials and of chemical routes; by following a number of heuristic and of rigorous rules, a list of prototype raw materials is rapidly developed. From this list it proves possible to create a reaction network connecting the selected raw materials with the target molecule, and 54 routes to MMA (including the two current commercial routes) were found to be of potential interest. Compared with the MMA case study, the VCM example moves further through the procedure to include pre-design capital costing; 14 reactions, resulting in 63 routes to VCM, are rapidly selected, and equilibrium and kinetics calculations reduce the number of promising VCM processes to 24. The operating conditions of the process reactors are also specified, and only three processes are eventually admitted to the final costing stage. 'Elementary plant sections', effecting only one reaction each, are costed separately for the three remaining processes, and it is shown that the three most promising processes can be analysed by joining together the 'sections' relevant to each process. The costing estimates are found to agree well with current practice. Furthermore, a graphical approach is devised to give quick estimates of product selling prices for a wide range of plant capacities and raw materials costs. The second major area of process synthesis considered is the synthesis of reactor networks integrated with the rest of the flowsheet. The complex reaction scheme by Van de Vusse (1964) was employed as an example in a pioneering study. A new procedural approach, which uses a hierarchy of three heuristics, is implemented. In this approach, the designer first devises a simple base case, and then methodically increases its complexity. A powerful analytical tool used is to target for maximum reactor system selectivity, in contrast with the target of maximum reactor yield proposed by previous workers. The dissertation ends with an example illustrating the scope for heat and power integration techniques in the later stages of the design of a flowsheet. A computerised model of a pressurised sulphuric acid plant is developed, and a number of suggestions are made for the improvement of a commercial process, leading to an increase of 15% in steam production.

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11

Novosselov, Igor V. "Chemical reactor networks for combustion systems modeling /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/7065.

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12

Gobby, Darren. "Design of catalytic microengineered reactors." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272329.

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13

Somerville-Marrs, Graham Paul. "The protection of batch chemical reactors against overpressure." Thesis, Loughborough University, 1987. https://dspace.lboro.ac.uk/2134/10481.

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A study was required of the methods of protecting chemical reactors against overpressure. At present the use of bursting discs, or pressure relief valves is not only normal but virtually mandatory. There are, however, some uncertainties and difficulties in the design of venting systems based on bursting discs and pressure relief valves and some evidence of failures of such systems. There is also some pressure to permit alternative means of protection based on control systems, including trip and interlock systems.

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14

Maciel, Filho Rubens. "Modelling and control of multitubular reactors." Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328962.

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15

Zanfir, Monica. "Catalytic plate reactors for endothermic-exothermic reaction coupling." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270199.

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16

Chung, Kenneth Hoi Kan. "Mixing in high throughput experimentation reactors." Thesis, University of Birmingham, 2009. http://etheses.bham.ac.uk//id/eprint/909/.

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The application of High Throughput Experimentation (HTE) stirred vessels in the catalyst and pharmaceutical industries enable the parallel screening of potential formulations. Such tasks only require a fraction of the raw material and experimental time that are needed in conventional lab scale reactors. However their small sizes (~ 15-250 ml) contribute to a low Reynolds Number, Re, which results in poor mixing efficiencies. Together with unconventional geometries, i.e. lack of baffles and simple impeller designs, their fundamentals are not fully understood. The present study applies Particle Image Velocimetry (2-D PIV) and Planar Laser Induced Fluorescence (PLIF) techniques to a HTE scale stirred vessel (T = 45 mm, V = 72 ml) to determine the mixing behaviour. Three mixing strategies: centreline unbaffled (U), conventional baffled (B) and off-centre eccentric agitator (E) configurations, were investigated using a pitched blade turbine (PBT). Experiments were performed in the high transitional regime (Re $ \approx$ 6000) using distilled water as the working fluid. A uniform power input of P/V = 168Wm$^{-3}$ was applied. A method based on multiple horizontal and vertical 2-D PIV measurements was used to reconstruct the 3-D flow field in each of these configurations, since the conventional 3-D PIV is unusable at this scale. It was found that the determination of turbulent kinetic energy (TKE) using the isotropic assumption was perfectly valid for (B), but will lead to a considerable underestimation in both (U) and (E). In addition to the three configurations, a square section vessel (S) (T = 41.5 mm, V = 72 ml) and regular vessel with a tilted impeller axis (T) were also studied. With a modified experimental procedure a log variance method for mixing time was applied using PLIF where all the usable pixels in an image were accounted for. Not only was (U) found to be highly inefficient, (B) also registered a slower mixing time due to a small amount of tracer being trapped behind the baffles, which makes the (E), (S) and (T) an even better choice in turbulent mixing. The use of (S) enabled the formation of a more compact HTE unit, also its trailing vortices were able to reach a height of y/H = 0.6, bringing more energy to the upper reaches of vessel, as visualised by angle resolved PIV measurements. The flow number of impeller and the amount of pseudo-turbulence were also determined and they agreed well with literature values. However in the laminar mixing regime using Polypropylene Glycol (PPG) as the Newtonian working fluid (μ = 0.4–0.8 Pa s, P/V = 0.6–5.5 kWm$^{-3}$, Re = 5–35), at low Re values, (S) only managed a mixing performance comparable to the (U) configuration as the baffling effect of its four corners are less pronounced. However, mixing performance improves in (S) at higher Re values. (B) and (E) gave a comparable mixing performance, suggesting (E) should always be adopted for its viability in both turbulent and laminar mixing regimes. For gas-liquid mixing using air and water (P$_G$/V = 168 Wm$^{-3}$, Q$_G$ = 0.5–1.0 vvm), an image analysis algorithm was developed which enabled measurement of gas and liquid phase velocities separately. In addition to the PBT, a Rushton Disk Turbine (RDT) was also used (C = D = 0.33T). The power input required for the small mixing vessel to achieve complete gas dispersion was not achievable at the required gas flow rate; hence the experiments are carried out in the flooding regime. This had the advantage of clearly discernible differences between gas and liquid flow pattern for validation purposes. A new image algorithm was written to separate out bubbles in the imaging plane which transforms the in-plane bubbles into tracer particles. The local velocities of the gas phase are then obtained using the conventional cross-correlation technique. The results showed qualitative agreement with experimental observations of global gas phase flow patterns in literature.

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17

Ajayi, Olukayode Oludamilola. "Prediction of the hydrodynamics in stirred tank reactors." Master's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/5337.

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Includes bibliographical references.
There have been several attempts to find a suitable set of model parameters for stirred tank reactors. In view of this, the present study investigated the performance of the standard k - ε model to predict the flow field in stirred tank reactors. The parametric analysis presented herein involves variation of the parameters in the model and an estimation of the overall error values between experimental data and the model predictions, which includes the mean velocities and the turbulent kinetic energy. The analysis also involves ascertaining the stability of the model via the moment convergence approach.

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18

Peschel, Andreas [Verfasser]. "Model-based design of optimal chemical reactors / Andreas Peschel." Aachen : Shaker, 2012. http://d-nb.info/1069045004/34.

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19

Thuto, Mosalagae. "Adaptive tracking for exothermic chemical reactors under input constraints." Thesis, University of Exeter, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323986.

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20

Patnaik, Sanjay. "Modelling of transport processes in chemical vapor deposition reactors." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14192.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1989.
Science hard copy bound in 2 v.
Includes bibliographical references (leaves 316-328).
by Sanjay Patnaik.
Ph.D.

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21

Leising, Guillaume M. "Radial heat transfer studies in low tube to particle diameter ratio fixed bed reactors." Link to electronic thesis, 2005. http://www.wpi.edu/Pubs/ETD/Available/etd-050205-154724/.

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22

Goeres, Darla Marie. "Design of model reactor systems for evaluating disinfectants against biofilm bacteria." Diss., Montana State University, 2006. http://etd.lib.montana.edu/etd/2006/goeres/GoeresD0506.pdf.

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23

Kwalik, Kristina Mary. "Bifurcation characteristics in closed-loop polymerization reactors." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/11711.

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24

Clark, Wayne William Philip. "The interfacial characteristics of falling film reactors." Thesis, University of Nottingham, 2001. http://eprints.nottingham.ac.uk/14303/.

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Falling film reactors are a very effective geometry in which to carry out fast exothermic gas-liquid reactions, because they allow easy removal of the heat produced. To optimise and improve falling film reactors, soundly based physical models are required. Existing models assume a flat liquid film combined with empirically-determined mass transfer coefficients, but there is growing evidence that this is unsatisfactory, since the interface is dominated by ripples and larger disturbance waves which have a significant effect on the mass and heat transfer rates through and into the film. The main objective of this study was the better understanding through experimental study of the interfacial characteristics of liquid falling films in the presence of a co-current down flow of air, with emphasis on the physical and hydrodynamic conditions encountered in current falling film reactor technology, so that the information obtained can be implemented in the enhancement of falling film reactor modelling. The liquids chosen were water, for validation of the measurement techniques through comparison with the literature, and two common falling film sulphonation reactor feedstocks; dodecylbenzene and ethoxylated alcohol. The experimental study consisted of film thickness and disturbance wave celerity measurements in a purpose built flow facility with a flat plate flow surface. A novel spatial film thickness measurement technique, the Light Absorption Imaging Technique (LAIT), was developed to give unparalleled spatial information on the interfacial characteristics of liquid films. A computer algorithm-based technique has been developed for categorisation of the spatial film data obtained by LAIT into substrate and disturbance wave regions, from which globally averaged characteristics of the interfacial structure have been obtained. Disturbance wave celerity measurements were obtained utilising the cross-correlated output signal from two light sources and a manual time-of-flight measurement technique using the images from a high-speed video camera. The study has provided a comprehensive set of data on the hydrodynamic structure of the interface, with and without the influence of a co-current down flow of air, for both water and actual sulphonation feed stocks as the liquid phase. The dramatic influence of both flow conditions and physical properties on interfacial characteristics has been demonstrated In particular, a transition has been observed of the disturbance wave structures in falling films due to the influence of a co- current airflow. Differences in the disturbance wave structure have been identified between the organic and water films after this transition.

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25

Santamaria, Ramiro J. M. "Deactivation and regeneration of fixed bed catalytic reactors." Thesis, University of Salford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356187.

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26

Zeng, Yisu. "Biodegradation of 2,4-dichlorophenol in sequencing batch anaerobic reactors." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/10148.

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A synthetic wastewater containing 20 mg/L 2,4-dichlorophenol (2,4-DCP) and medium-strength carbonaceous co-substrate (7 g COD/L) was used to investigate the feasibility of treating chlorophenols in laboratory-scale sequencing batch upflow anaerobic sludge blanket reactors, designated as SBAR. The specific organic loading rate (SOLR) and specific 2,4-DCP loading rate (SDCPLR) tested were 0.35, 0.53, 0.70 g COD/g VSS/d and 1.0, 1.5 and 20 mg 2,4-DCP/g VSS/d, respectively. For each SOLR and SDCPLR operating condition, three different fill/react ratios, 0.33, 0.66 and 1.00 were examined in order to assess the performance of SBAR operating strategies. One continuous upflow anaerobic sludge blanket (UASB) reactor used as the control was operated at three SOLR and SDCPLR corresponding to those applied to SBARs. Experimental results show that laboratory-scale SBARs were able to treat 2,4-DCP contaminated wastewater in addition to medium-strength carbonaceous co-substrate. The over all removal efficiencies of SBARs were almost 100% for 2,4-DCP and ranged from 72.5% to 94.2% for carbonaceous co-substrate. Under studied conditions, the performance of the continuous flow reactor was quite similar to that of sequencing batch reactors. Removal efficiencies for the continuous flow reactor were almost 100% for 2,4-DCP and ranged from 84.2% to 93.3% for COD. The major biodegradation product of 2,4-DCP in both sequencing batch and continuous UASB reactors was 4-monochlorophenol. This experimental work also confirmed earlier observations that SOLR significantly influenced the overall COD removal efficiency of the SBAR, and SOLR based on fill time (SOLR)$\sb{\rm f}$ is an important design parameter for SBAR systems. Experimental data from this study were also compared with the simulated results obtained using a previously developed dynamic SBAR model. It was verified that this model can predict the SBAR performance reasonably well.

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27

Truter, Lara. "Development of a zeolite washcoating technique for microchannel reactors." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/10855.

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Microreactor technology is becoming an increasingly active research field in terms of chemical reaction engineering and process intensification. An important feature of microreactor technology is the requirement of a catalyst layer.

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28

Ahola, J. (Juha). "Reaction kinetics and reactor modelling in the design of catalytic reactors for automotive exhaust gas abatement." Doctoral thesis, University of Oulu, 2009. http://urn.fi/urn:isbn:9789514290305.

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Abstract The tightening environmental legislation and technological development in automotive engineering form a challenge in reactor design of catalytic reactors for automotive exhaust gas abatement. The catalytic reactor is the heart of the exhaust aftertreatment processes, but it can be seen also just as one subsidiary part of vehicles. The aim of this work is to reveal applicable kinetic models to predict behaviour of the particular catalysts and to establish guidelines for modelling procedures and experimentation facilitating catalytic reactor design, especially in the field of automotive exhaust gas abatement. The studies in this thesis include catalyst kinetics with synthetic exhaust gas composition in stoichiometric and net oxidative conditions, DRIFT measurements, and the warm-up of three-way catalysts in real conditions. Knowledge on surface concentrations facilitates kinetic model construction and discrimination. For example, identification of even semi-quantitative surface concentrations may lead to a successful falsification of incorrect kinetic model candidates. Especially, that is clearly seen in cases where models predict the same kind of gas phase behaviour but different kinds of surface concentration profiles. The transient kinetic experiments could give a hint on predominant reaction mechanism, support quantifying of the adsorption capacity and reveal the impact of surface phenomena on reactor dynamics. The level of model complexity should be adapted depending on the purpose of the model. For example, it is mostly convenient for reactor design purposes to perceive only one type of active sites even in a case of mechanical mixture of different catalytic materials; whereas the optimisation of catalyst content demands the management of every prominent site type separately. Or, when a catalytic material has been selected, the stationary kinetic model is, in most cases, adequate for the catalytic converter design and structural optimization for warm-up conditions.

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Bhatelia, Tejas Jagdish. "Novel reactors for multiphase processes." Thesis, Curtin University, 2009. http://hdl.handle.net/20.500.11937/2418.

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Process intensification tools, such as the capillary reactor, offer several benefits to the chemical process industries due to the well-defined high specific interfacial area available for heat and mass transfer, which increases the transfer rates, and due to low inventories, they also enhance the safety of the process. This has provided motivation to investigate three such tools, namely the capillary microreactor, spinning disc and rotating tube reactors, in this study.The gas-liquid slug flow capillary microreactor intensifies reactor performance through internal circulation caused by the shear between the continuous phase/wall surface and the slug axis, which enhances the diffusivity and consequently increases the reaction rates. However, integrating the complex hydrodynamics of this reactor with its chemical kinetics is a mathematically challenging task. Therefore, in this study, a simple-to-complex approach, using a set of state-of-the-art computational fluid dynamic tools, has been used. Firstly, simulations were performed without any chemical reaction to ascertain the extent of slug flow regime. The model also clearly captured the slug flow generation mechanism which can be used to structurally optimize the angle of entry in these reactors. Finally, the hydrodynamic model was also capable of estimating the pressure drop and slug lengths. After successfully simulating the hydrodynamics of the system, a reaction model was incorporated to study the chemical reaction kinetics. The results were compared with the published experimental work and were found to be in good agreement.The spinning disc reactor utilizes the centrifugal and shear forces to generate thin liquid films characterized with intense interfering waves. This enables a very high heat transfer coefficients to be realized between the disc and liquid, as well as very high mass transfer between the liquid and the bulk gas phase. The waves formed also produce an intense local mixing with very little back mixing. This makes a spinning disc reactor an ideal contactor for multiphase processes. The focus of this study has been to elucidate the hydrodynamic behaviour of the liquid film flow over the horizontal spinning disc. Investigations were also performed to elaborate the local and overall hydrodynamic characteristics of a fully developed spinning disc reactor. Simulation results showed a continuous linear liquid film on the horizontal spinning disc and intense mixing performance in the annulus of the reactor around the disc surface. Finally, the film thickness data from the simulations were compared with the limited amount of data available for this novel process.Rotating tube reactor also uses centrifugal forces to generate the liquid film and a high degree of mixing along with an improved control over the reactant retention times. In this work we have conducted a CFD analysis to understand the hydrodynamics of this new technology for future developments.

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Al-Gailani, Bashar Riyadh M. "Microfabricated chemical reactors for gas-phase catalytic reactions and micrototal analytical systems for environmental monitoring." Thesis, University of Hull, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415802.

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Zwahlen, Andreas G. "Reaction and deactivation kinetics of isobutane, using a concentration-controlled internal-recycle reactor /." Title page, contents and summary only, 1989. http://web4.library.adelaide.edu.au/theses/09PH/09phz971.pdf.

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Wales, Michael Dean. "Membrane contact reactors for three-phase catalytic reactions." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/20589.

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Doctor of Philosophy
Chemical Engineering
Mary E. Rezac
Membrane contact reactors (MCRs) have been evaluated for the selective hydro-treating of model reactions; the partial hydrogenation of soybean oil (PHSO), and the conversion of lactic acid into commodity chemicals. Membranes were rendered catalytically active by depositing metal catalyst onto the polymer "skin" of an asymmetric membrane. Hydrogen was supplied to the support side of the membrane and permeated from the support side to the skin side, where it adsorbed directly onto the metal surface. Liquid reactant was circulated over the membrane, allowing the liquid to come into direct contact with the metal coated surface of the membrane, where the reaction occurred. Our membrane contact reactor approach replaces traditional three-phase batch slurry reactors. These traditional reactors possess inherent mass transfer limitations due to low hydrogen solubility in liquid and slow diffusion to the catalyst surface. This causes hydrogen starvation at the catalyst surface, resulting in undesirable side reactions and/or extreme operating pressures of 100 atmospheres or more. By using membrane reactors, we were able to rapidly supply hydrogen to the catalyst surface. When the PHSO is performed in a traditional slurry reactor, the aforementioned hydrogen starvation leads to a high amounts of trans-fats. Using a MCR, we were able to reduce trans-fats by over 50% for equal levels of hydrogenation. It was further demonstrated that an increase in temperature had minimal effects on trans-fat formation, while significantly increasing hydrogenation rates; allowing the system to capture higher reaction rates without adversely affecting product quality. Additionally, high temperatures favors the hydrogenation of polyenes over monoenes, leading to low amounts of saturated fats. MCRs were shown to operator at high temperatures and: (1) capture high reaction rates, (2) minimize saturated fats, and (3) minimize trans-fats. We also demonstrated lactic acid conversion into commodity chemicals using MCRs. Our results show that all MCR experiments had faster reaction rate than all of our controls, indicating that MCRs have high levels of hydrogen coverage at the catalyst. It was also demonstrated that changing reaction conditions (pressure and temperature) changed the product selectivities; giving the potential for MCRs to manipulate product selectivity.

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Hannon, J. "Mixing and chemical reaction in tubular reactors and stirred tanks." Thesis, Cranfield University, 1992. http://dspace.lib.cranfield.ac.uk/handle/1826/11368.

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Fluid flow patterns and turbulence levels are instrumental in determining chemical reactor performance. Parameters such as stirrer type and size, fluid physical properties, chemical species concentrations and flow rates can strongly influence the safety, efficiency and reliability of reactors, with consequent cost implications. In this project, Computational Fluid Dynamics has been used to obtain insight into the characteristics of tubular and stirred tank chemical reactors. Attention is focused on single phase liquid isothermal turbulent flows. Turbulence theory is used to select and develop appropriate physical models for both fluid flow and chemical reaction rates. Many previously used models are shown to be of limited validity. Results of simulations are compared with experimental measurements of the flow field and progress of both simple and complex chemical reactions. Comparisons are generally favourable. Limitations of the present approach are highlighted and future refinements and extensions suggested.

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Hehn, Martin Christoph. "Diagnostics and modelling of atmospheric pressure chemical vapour deposition reactors." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/diagnostics-and-modelling-of-atmospheric-pressure-chemical-vapour-deposition-reactors(e3a692e7-2b47-4d5d-9d4c-3997a88893f6).html.

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In the manufacturing process of float glass often atmospheric pressure chemical vapour deposition (APCVD) reactors are integrated on-line for the deposition of functional thin solid films. Such functional films have applications in architectural glass, flat panel displays and solar cells. As glass moves downstream in the process, the thin film is deposited at temperatures between 500 to 700°C. The high temperatures make it difficult to monitor the deposition process and thin film quality control is commonly done at the end of the line or at lower temperatures. A time delay therefore exists between the point of thin film deposition and subsequent quality control, which can lead to large quantities of defective product being produced before faults are detected. It is therefore desirable to monitor in the APCVD reactor for rapid feedback of unexpected deviations from desired process conditions, reaction progress and fault detection. High uniformity of film properties across the substrate are important, but APCVD reactors are often empirically designed and the detailed chemical reaction mechanism is unknown. This leads to inefficient gas flow patterns and precursor utilization as well as difficulties in the design of new reactors. The APCVD deposition of tin oxide from the mono-butyl-tin tri-chloride (MBTC) is an example of such a process. Optical monitoring instruments in-situ and in-line on the APCVD reactor provided rapid feedback about process stability and progress non-invasively. Near infrared diode laser absorption spectroscopy (NIR-LAS) monitored the concentration of the reaction species hydrogen chloride (HCl) in-situ and spatially in the coating zone. A mid-infrared grating absorption spectrometer (IR-GAS) with novel pyro-electric array detector monitored the concentration of precursor entering the coating system simultaneously. In combination these instruments provide the means for rapid process feedback. Fourier transform infrared absorption spectroscopy (FTIR) was used to investigate the unknown decomposition pathway of the precursor to find the yet unknown key tin radical that initiates film growth. Stable species forming during MBTC decomposition over a temperature range of 170 to 760°C were investigated but the tin intermediate remains unknown. Computational fluid dynamics (CFD) is routinely employed in research and industry for the numerical simulation of CVD processes in order to predict reactor flow patterns, deposition rates, chemical species distribution or temperature profiles. Two and three dimensional models with complex geometries and detailed reaction models exist. A three dimensional computational fluid dynamics (CFD) model of the used APCVD reactor was built using the Fluent CFD software. The numerical simulation included a chemical model that predicted qualitatively the chemical species distribution of hydrogen chloride in the gas phase. This was confirmed through comparison with NIR-LAS results. Design shortcomings due to inefficient flow patterns were also identified. In combination the optical tools developed provide the means for safe and efficient manufacturing of thin films in APCVD reactors. CFD simulations can be used to increase precursor utilization and film uniformity in the development of new reactor designs.

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Brown, Wayne A. "Real-time control strategies for cyclical biological reactors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0023/NQ50121.pdf.

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36

Alhamad, Bassam. "A framework for advanced/intelligent operation of emulsion copolymerisation reactors." Phd thesis, Department of Chemical Engineering, 2005. http://hdl.handle.net/2123/5828.

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37

Abegão, Fernando José Russo. "Magnetic resonance studies of temperature and chemical composition in trickle bed reactors." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609951.

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38

Cooper, Judy. "A numerical model for char combustion in packed bed reactors." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/9679.

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A numerical simulation of the combustion of centimeter-sized char particles in an overfeed fuel bed is presented. One-dimensional mass, species and energy balances for the reading system are solved by finite volume discretization methods to predict operating curves and temperature and concentration profiles for char combustion under a variety of conditions. The simulation is unique in that it employs separate gas and solid phase energy balances with finite-rate CO kinetics and a particle number balance to account for the shrinkage of the char particles as they descend through the bed. All the major energy transport processes, such as particle-to-fluid heat and mass transfer, conduction, convection and radiation, are modelled. The simulation was run for beds of 1-3 cm particles ranging from 30-60 cm in height. The range of air flow rates studied ranged from 0.036 to 0.87 m/s. Comparisons between predicted gas and temperature profiles and similar profiles obtained from the literature generally showed good agreement, indicating that the simulation was reliable enough for use as a design tool over the range of conditions that were studied. The simulation proved to be quite sensitive to choices of the heat and mass transfer coefficients and also to the CO$\sb2$ reduction rate expression, indicating that there is a need for more research on large-particle kinetics and high-temperature packed bed energy transport processes.

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39

Kim, Seok-Jhin. "High Temperature Water Gas Shift Reaction in Zeolite Membrane Reactors." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1321888491.

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40

Sajjadi, Emami Shahriar. "Particle formation and growth in semibatch emulsion polymerisation reactors." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/12373.

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An investigation of emulsion polymerisation of butyl acrylate in batch and semibatch reactors has been carried out. The important phenomena of particle formation and kinetics in semibatch emulsion reactors with neat monomer feed and monomer emulsion feed have been studied. An investigation of batch emulsion polymerisation of butyl acrylate was also undertaken in order to provide the supporting evidence to elucidate particle formation in the semibatch emulsion process. Different start-up procedures were studied to determine their effect on the particle formation and kinetics of the polymerisation reaction. The effects of monomer distribution, emulsifier distribution, initiator distribution, feed rate, temperature and pre-period time on the particle formation and steady-state rate of polymerisation were investigated. Experimental studies reveal that particle formation in semibatch emulsion polymerisation is influenced by partitioning of ingredients, such as emulsifier and monomer, between the charge and the feed rate and controlling the growth rate of particles at monomer-starved conditions. The latter is applied by adjusting the monomer or monomer emulsion feed rate at a desired level. Changes in start-up procedure were found to have a significant effect not only on the transients before a steady-state, but also on the ultimate steady-state rate of polymerisation reaction achieved and final number of particles obtained. All variables affecting primary and secondary particle formation, and especially emulsifier concentration, could equally influence the steady-state rate of polymerisation reaction. Evidence was obtained indicating that secondary nucleation can occur through homogenous nucleation. The particle size distribution (PSD) development in the course of reaction for the semibatch emulsion process was investigated. Partitioning of ingredients between the charge and the feed and monomer starved nucleation were founa to be the main two factors that control the PSD and number of particles formed.

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41

Abashar, Mohd Elbashir E. "Bifurcation, instability and chaos in fluidized bed catalytic reactors." Thesis, University of Salford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386532.

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42

Adikesavalu, Ravichandran. "Preliminary modeling of in-duct desulfurization using condensation aerosols." Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177616476.

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43

Richards, Martyn W. "Chemical reactions of caesium, tellurium and oxygen with transition metal alloys." Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276201.

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44

Steinbach, Paul B. "An electrothermal fluidized-bed carbon-particle plasma reactor for hazardous waste treatment /." free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9823315.

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45

Samer, Charles J. "Polymer-stabilized miniemulsion polymerization in a continuous stirred-tank reactor." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/11142.

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46

Lee, Hsueh-Chi. "Emulsion polymerization in a seed-fed continuous stirred-tank reactor." Diss., Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/11860.

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47

Diez-Lazaro, Alvaro. "Studies in process analysis and control in batch reactors." Thesis, University of Strathclyde, 2002. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21206.

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This work is part of a number of projects dealing with the development of novel techniques for better analysis and control of chemical processes carried out in batch reactors. The problems of pH measurement and sampling, linked to the implementation of NMR and HPLC on-line analysers, are presented as key areas in this development work. Also, part of the engineering work summarised in this thesis assisted the work of other researchers who participated in the project. In the area of sampling, the difficulties associated with the collection of representatives samples from agitated vessels are introduced. Also, the ideas of calibration and modelling of sampling systems are presented. Modelling tests were used to optimise the design and development of a fast sampling loop system to obtain representative samples from stirred vessels. In addition to this, the modelling studies also assisted the work of other researchers in the project who needed the kinetic and heat-exchange parameters for the process of esterification of crotonic acid. The fast sampling loop was shown to be adequate for the implementation of a low-field NMR system for on-line analysis. The development of discrete samplers designed to collect, dilute and deliver representative samples for LC analysis is also covered in this work. A Mark IV prototype of LC sampler was tested and developed to acceptable levels. In the area of pH measurement the advantages and disadvantages of the use of thermally grown iridium-oxide electrodes are introduced. Their response was compared to that of standard glass electrodes and found to be faster, more stable at high temperatures and no alkaline error was observed. However, the problem of drift of the signals was not fully overcome and it is presented as the limiting factor in the use of the sensors for on-line industrial measurements. Finally, a new type of total iridium-oxide probe is presented.

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48

Mushonga, Sylvester Paul. "pH control using two continuous stirred tank reactors in series." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1595785.

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The control of pH is one of the most difficult chemical control schemes in industry. Often, large tanks are used to control pH. The pH in these large tanks frequently overshoots the desired pH set-point and usually takes a long time to reach the desired set-point. In this work, a conceptual pH control process was developed and tested by using two small continuous stirred tank reactors (CSTRs). In this two-step system, the bulk of the neutralization is carried out in the first reactor and then fine-tuned in the second reactor. The conceptual neutralization model was built by analyzing the chemistry behind pH. Because pH is a nonlinear function of hydrogen ion concentration (pH= -log [H⁺]), the hydrogen ion concentration was chosen as the process measured variable. The slope (Gain) was calculated from a titration curve obtained from a polynomial derived from neutralization chemistry and a practical titration. The process dynamics were then fitted into the classic proportional, integral, and differential (PID) controller using the Internal Model Control (IMC) tuning method. The robust tuning parameters produced by the IMC method were able to bring the pH in the first CSTR to the desired set-point. In addition, disturbances from vibrations produced by the pump and magnetic stirrer, slight variations in reactant concentration, and pH probe lags were easily eliminated. Most importantly, pH in the second CSTR settled on the desired neutral set-point of pH 7.0 after brief oscillations. The process was repeatable when the reactors where scaled up one hundred times using synthetic waste water. Autotune variation results produced similar process dynamics to those produced by calculating the slope from the titration curve.

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49

Cartland-Glover, Gregory M. "Use of computational fluid dynamics in the design of bubble column reactors." Thesis, Aston University, 2002. http://publications.aston.ac.uk/9648/.

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Investigations into the modelling techniques that depict the transport of discrete phases (gas bubbles or solid particles) and model biochemical reactions in a bubble column reactor are discussed here. The mixture model was used to calculate gas-liquid, solid-liquid and gasliquid-solid interactions. Multiphase flow is a difficult phenomenon to capture, particularly in bubble columns where the major driving force is caused by the injection of gas bubbles. The gas bubbles cause a large density difference to occur that results in transient multi-dimensional fluid motion. Standard design procedures do not account for the transient motion, due to the simplifying assumptions of steady plug flow. Computational fluid dynamics (CFD) can assist in expanding the understanding of complex flows in bubble columns by characterising the flow phenomena for many geometrical configurations. Therefore, CFD has a role in the education of chemical and biochemical engineers, providing the examples of flow phenomena that many engineers may not experience, even through experimentation. The performance of the mixture model was investigated for three domains (plane, rectangular and cylindrical) and three flow models (laminar, k-e turbulence and the Reynolds stresses). mThis investigation raised many questions about how gas-liquid interactions are captured numerically. To answer some of these questions the analogy between thermal convection in a cavity and gas-liquid flow in bubble columns was invoked. This involved modelling the buoyant motion of air in a narrow cavity for a number of turbulence schemes. The difference in density was caused by a temperature gradient that acted across the width of the cavity. Multiple vortices were obtained when the Reynolds stresses were utilised with the addition of a basic flow profile after each time step. To implement the three-phase models an alternative mixture model was developed and compared against a commercially available mixture model for three turbulence schemes. The scheme where just the Reynolds stresses model was employed, predicted the transient motion of the fluids quite well for both mixture models. Solid-liquid and then alternative formulations of gas-liquid-solid model were compared against one another. The alternative form of the mixture model was found to perform particularly well for both gas and solid phase transport when calculating two and three-phase flow. The improvement in the solutions obtained was a result of the inclusion of the Reynolds stresses model and differences in the mixture models employed. The differences between the alternative mixture models were found in the volume fraction equation (flux and deviatoric stress tensor terms) and the viscosity formulation for the mixture phase.

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50

Bhatelia, Tejas Jagdish. "Novel reactors for multiphase processes." Curtin University of Technology, Science and Engineering, Department of Chemical Engineering, 2009. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=129027.

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Process intensification tools, such as the capillary reactor, offer several benefits to the chemical process industries due to the well-defined high specific interfacial area available for heat and mass transfer, which increases the transfer rates, and due to low inventories, they also enhance the safety of the process. This has provided motivation to investigate three such tools, namely the capillary microreactor, spinning disc and rotating tube reactors, in this study.
The gas-liquid slug flow capillary microreactor intensifies reactor performance through internal circulation caused by the shear between the continuous phase/wall surface and the slug axis, which enhances the diffusivity and consequently increases the reaction rates. However, integrating the complex hydrodynamics of this reactor with its chemical kinetics is a mathematically challenging task. Therefore, in this study, a simple-to-complex approach, using a set of state-of-the-art computational fluid dynamic tools, has been used. Firstly, simulations were performed without any chemical reaction to ascertain the extent of slug flow regime. The model also clearly captured the slug flow generation mechanism which can be used to structurally optimize the angle of entry in these reactors. Finally, the hydrodynamic model was also capable of estimating the pressure drop and slug lengths. After successfully simulating the hydrodynamics of the system, a reaction model was incorporated to study the chemical reaction kinetics. The results were compared with the published experimental work and were found to be in good agreement.
The spinning disc reactor utilizes the centrifugal and shear forces to generate thin liquid films characterized with intense interfering waves. This enables a very high heat transfer coefficients to be realized between the disc and liquid, as well as very high mass transfer between the liquid and the bulk gas phase. The waves formed also produce an intense local mixing with very little back mixing. This makes a spinning disc reactor an ideal contactor for multiphase processes. The focus of this study has been to elucidate the hydrodynamic behaviour of the liquid film flow over the horizontal spinning disc. Investigations were also performed to elaborate the local and overall hydrodynamic characteristics of a fully developed spinning disc reactor. Simulation results showed a continuous linear liquid film on the horizontal spinning disc and intense mixing performance in the annulus of the reactor around the disc surface. Finally, the film thickness data from the simulations were compared with the limited amount of data available for this novel process.
Rotating tube reactor also uses centrifugal forces to generate the liquid film and a high degree of mixing along with an improved control over the reactant retention times. In this work we have conducted a CFD analysis to understand the hydrodynamics of this new technology for future developments.

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Dissertations / Theses on the topic 'Chemical reactors'

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