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1
Kennedy, Mark William. "Chlorination of magnesium carbonate in a stirred tank reactor". Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=24061.
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A study was conducted on the reaction of solid MgO formed from magnesite (MgCO$ sb3),$ with Cl$ sb2$ and CO gas, in a stirred tank reactor containing a liquid bath of MgCl$ sb2.$ The reaction rate was found to be controlled by CO mass transfer from the gas to the liquid phase and was zero order with respect to the concentration of MgO. At temperatures from 743 to $824 sp circ$C, the reaction rate exhibited an activation energy of 80 kJ/mol, which is typical of a diffusion controlled reaction.The chlorinaton rate was effected by both temperature and CO/Cl$ sb2$ ratio and estimates of the optimum conditions were obtained: temperature $(856.6 sp circ$C) and ratio of CO/Cl$ sb2$ (1.24). The addition of an inert gas (N$ sb2)$ to the reagent mixture was found to decrease the reaction rate. Iron was found to have a negligible effect on reaction rate at the levels tested (up to 560 P.P.M.).
For those experiments conducted at $ rm 820 sp circ C pm 5 sp circ C,$ an overall correlation was obtained which related the MgO reaction rate, with impeller power (kW/m$ sp3),$ superficial gas velocity (cm/s) and the partial pressure of CO (atm.): rm Rate = 0.609 (P sb{g}/V sb1) sp{0.35} (v sb{s}) sp{0.64} (P sb{CO}) sp{1.14}, (kgmol/m sp3/h) eqno lbrack 55 rbrack. ixing and gas dispersion characteristics were defined for the specific impeller/tank geometry used in these experiments.
Using the results presented here, it would be possible to estimate the size and number of commercial stirred tank chlorination reactors, which would be required to produce any specified quantity of magnesium, starting from magnesite, with an accuracy of $ pm$44%, with 95% confidence.
2
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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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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Hu, Lin-Wen. "Thermal hydraulic mixing transients in the MIT research reactor core tank". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10814.
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Dong, Jie. "Modelling of multiphase flow containing ionic liquids in a stirred tank reactor". Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/46880/.
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Stirred tanks are widely used in the chemical reactions and the mixing operations for process industries to enable high product quality and process efficiency. Despite there being a large body of studies on the hydrodynamics of water in the stirred tanks, the understandings of the hydrodynamics of the ionic liquids in the stirred tanks are still very limited. In this study, Computational Fluid Dynamics (CFD) modelling is used to investigate the detailed flow characteristics of the single and multiphase ionic liquid flows in the stirred tanks which are experimentally validated using Particle Image Velocimetry (PIV). The ANSYS FLUENT was employed in this investigation to carry out the CFD simulation. Initially, the hydrodynamics of single phase flows were numerically studied where the single phase turbulent water flow and single phase transitional ionic liquid flow were modelled using a RANS and LES approach respectively in the three stirred tanks equipped with different bottom shapes and length of baffles. The simulation results indicated that the bottom shape and baffles’ length have significant effect on the flow field in a stirred tank when the water was operated in the turbulent state, where a large dead zone region was identified below the impeller. However, the magnitude of the dead zone region reduced a lot when the ionic liquid was operated in the transitional state. Before carrying out the gas-ionic liquid multiphase flow simulation in a stirred tank, the bubble size needs to be identified as it is crucial information for the accurate gas-ionic liquid multiphase flow modelling. In order to obtain the bubble size data, a high speed camera and a microscope were employed to experimentally measure the bubble size in the ionic liquid solutions. The correlations between the bubble size in the ionic liquid solutions and the impeller agitation speed were established. It showed that both the bubble breakage and coalescence has significant effect on determining bubble size in the ionic liquid. In addition, it was suggested that the surface tension of the ionic liquid is more important than the liquid viscosity on affecting the bubble size in the stirred tank. Afterward, the gas-ionic liquid multiphase flow modelling was carried out in the stirred tank at various impeller speeds and gassing rates. The simulation results indicated that the presence of gas phase did not have significant effect on changing the flow of liquid phase under the selected operation conditions due to the small bubble size, low gas flow rate and high viscosity of ionic liquid. The gas phase followed well with the liquid phase and circulated in the majority region of the stirred tank, which implied better gas holdup and mass transfer of the multiphase flow system. A correlation was proposed to predict the impeller power consumption of the gas-ionic liquid transitional flow in a stirred tank agitated by a Rushton turbine impeller. Finally, in order to validate the above single phase and multiphase flow CFD models adopted in this study, an experimental rig was established and the advanced visualization technique Particle Image Velocimetry (PIV) was used to measure the single phase water and ionic liquid flows and gas-ionic liquid multiphase flow in a stirred tank. The PIV data showed agreement with the CFD results in terms of the flow pattern and velocity components, which indicates good accuracy of the computational models and approaches presented in this investigation.
6
Singh, Harminder. "Modelling of shear sensitive cells in stirred tank reactor using computational fluid dynamics". Thesis, University of Canterbury. Chemical and Process Engineering, 2011. http://hdl.handle.net/10092/5684.
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Animal cells are often cultured in stirred tank reactors. Having no cell wall, these animal cells are very sensitive to the fluid mechanical stresses that result from agitation by the impeller and from the rising and bursting of bubbles, which are generated within the culture medium in the stirred tank to supply oxygen by mass transfer to the cells. If excessive, these fluid mechanical stresses can result in damage/death of animal cells. Stress due to the rising and bursting of bubbles can be avoided by using a gas-permeable membrane, in the form of a long coiled tube (with air passing through it) within the stirred tank, instead of air-bubbles to oxygenate the culture medium. Fluid mechanical stress due to impeller agitation can be controlled using appropriate impeller rotational speeds. The aim of this study was to lay the foundations for future work in which a correlation would be developed between cell damage/death and the fluid mechanical stresses that result from impeller agitation and bubbling. Such a correlation could be used to design stirred-tank reactors at any scale and to determine appropriate operating conditions that minimise cell damage/death due to fluid mechanical stresses.
Firstly, a validated CFD model of a baffled tank stirred with a Rushton turbine was developed to allow fluid mechanical stresses due to impeller agitation to be estimated. In these simulations, special attention was paid to the turbulence energy dissipation rate, which has been closely linked to cell damage/death in the literature. Different turbulence models, including the k-ε, SST, SSG-RSM and the SAS-SST models, were investigated.
All the turbulence models tested predicted the mean axial and tangential velocities reasonably well, but under-predicted the decay of mean radial velocity away from the impeller. The k-ε model predicted poorly the generation and dissipation of turbulence in the vicinity of the impeller. This contrasts with the SST model, which properly predicted the appearance of maxima in the turbulence kinetic energy and turbulence energy dissipation rate just off the impeller blades. Curvature correction improved the SST model by allowing a more accurate prediction of the magnitude and location of these maxima. However, neither the k-ε nor the SST models were able to properly capture the chaotic and three-dimensional nature of the trailing vortices that form downstream of the blades of the impeller. In this sense, the SAS-SST model produced more physical predictions. However,this model has some drawbacks for modelling stirred tanks, such as the large number of modelled revolutions required to obtain good statistical averaging for calculating turbulence quantities. Taking into consideration both accuracy and solution time, the SSG-RSM model was the least satisfactory model tested for predicting turbulent flow in a baffled stirred tank with a Rushton turbine.
In the second part of the work, experiments to determine suitable oxygen transfer rates for culturing cells were carried out in a stirred tank oxygenated using either a sparger to bubble air through the culture medium or a gas-permeable membrane. Results showed that the oxygen transfer rates for both methods of oxygenation were always above the minimum oxygen requirements for culturing animal cells commonly produced in industry, although the oxygen transfer rate for air-bubbling was at-least 10 times higher compared with using a gas-permeable membrane. These results pave the way for future experiments, in which animal cells would be cultured in the stirred tank using bubbling and (separately) a gas-permeable membrane for oxygenation so that the effect of rising and bursting bubbles on cell damage/death rates can be quantified. The effect of impeller agitation on cell damage/death would be quantified by using the gas permeable membrane for oxygenation (to remove the detrimental effects of bubbling), and changing the impeller speed to observe the effect of agitation intensity.
In the third and final part of this work, the turbulent flow in the stirred tank used in the oxygenation experiments was simulated using CFD. The SST turbulence model with curvature correction was used in these simulations, since it was found to be the most accurate model for predicting turbulence energy dissipation rate in a stirred tank. The predicted local maximum turbulence energy dissipation rate of 8.9x10¹ m2/s3 at a rotational speed of 900 rpm was found to be substantially less than the value of 1.98x10⁵ m2/s3 quoted in the literature as a critical value above which cell damage/death becomes significant. However, the critical value for the turbulence energy dissipation rate quoted in the literature was determined in a single-pass flow device, whereas animal cells in a stirred tank experience frequent exposure to high turbulence energy dissipation rates (in the vicinity of the impeller) due to circulation within the stirred tank and long culture times. Future cell-culturing experiments carried out in the stirred tank of this work would aim to determine a more appropriate critical value for the turbulence energy dissipation rate in a stirred tank, above which cell damage/death becomes a problem.
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Leguay, Caroline. "Hydrodynamics and mass transfer studies of a self-inducing gas-liquid stirred tank reactor". Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621178.
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Zhang, Xiaochun. "Sequencing batch reactor treatment of oily wastewater from can manufacturing and gasoline tank bottoms". Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43075.
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This study was a full-scale investigation of SBR for the treatment of oily wastewater
with determination of the effects of different operating conditions on process performance.
It was demonstrated that under a rather complex situation, the performance
of the SBR could be significantly improved, compared to the results prior to the
study. In contrast to the low COD reduction, significantly higher BOD5 removals were achieved. When the waste was only composed of wasted oils, the BOD, in the effluent
averaged 179 mg/I for an average removal of 87%. Also good reductions of phenols and oil & grease were attained during the study.
Based on a thorough evaluation of the results the following specific conclusions are made.Master of Science
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Adkins, Carol Leslie Jones Seinfeld John H. Flagan Richard C. "Use of a continuous stirred tank reactor for the study of aqueous aerosol chemistry". Diss., Pasadena, Calif. : California Institute of Technology, 1988. http://resolver.caltech.edu/CaltechTHESIS:12042009-080025691.
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Thesis (Ph. D.)--California Institute of Technology, 1988. UM #88-03,381.Advisor names found in the Acknowledgments pages of the thesis. Title from home page. Viewed 02/19/2010. Includes bibliographical references.
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Basu, Nandini. "Nonlinear chemical phenomena in a continuously stirred tank reactor (CSTR) containing chlorine dioxide and sulfite /". free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426045.
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Ford, Jason J. "Using X-ray computed tomography to measure local gas holdup in a stirred tank reactor". [Ames, Iowa : Iowa State University], 2006.
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Lennox, Martin. "The adaptation of self-cycling fermentation to a continuously-stirred tank reactor for xenobiotic degradation /". Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99416.
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The technique of self-cycling fermentation (SCF) was adapted to a continuously-stirred tank reactor (CSTR) using the production of CO2 as the monitored parameter in the feedback control loop, mechanical level switches to determine the volumes removed and replaced during reactor cycling and a non-50% harvest fraction. Previous work with the technique indicated the potential for improvement of SCF by applying these changes. The work was performed to develop a system that can be used to study the degradation of xenobiotic compounds when exposed to microbial cultures. The development of the experimental apparatus was done using the degradation of the plasticizer di-(2-ethylhexyl) adipate by Rhodococcus rhodochrous.The experimental results demonstrated that CO2 production could be used in the feedback control loop to successfully trigger cycling of the reactor. The use of a 65% harvest fraction demonstrated that a 50% harvest fraction was not necessary to operate SCF.
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Brito, Bernardo Nascimbeni de. "Effect of the sulfide, pH and temperature on anammox activity in a continuous flow stirred-tank reactor". Universidade Federal de Viçosa, 2015. http://www.locus.ufv.br/handle/123456789/7373.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Um promissor processo biológico para a remoção de elevadas concentrações de nitrogênio de águas residuárias vem sendo estudado nos últimos 20 anos. O processo possibilita uma redução substancial nos requisitos de aeração, fontes de carbono e baixa produção de biomassa. Durante 9 meses, um reator continuo de mistura completa com nitrificação parcial e processo anammox ocorrendo simultaneamente em único estágio foi operado com medições e análises regulares. Foram avaliados o desempenho do reator e sua capacidade de recuperação após exposição a curto-prazo da adição de sulfeto, pH em condições ácidas e temperaturas abaixo dos valores ótimos. O reator demonstrou ser sensível a pequenas variações de pH. Observou-se que o reator operando com valores de pH inferiores a 6,71 ± 0,01, apresentou perda na eficiência de remoção de amônia. As concentrações de 0,1 e 0,25 mg S L -1 de sulfeto testados apresentaram efeito inibitório. A faixa de temperatura de 36 – 25°C testada, não comprometeu a performance do reator.
A new biological process that removes high concentrations of nitrogen from residual waters has been studied for the last twenty years. Such process allows for a substantial reduction on aeration and carbon sources requirements while also producing low levels of biomass. For nine months, a continuum reactor composed of a complete mixture with partial nitrification and the anammox process occurring simultaneously was operated with regular mediation and analysis. An evaluation was conducted on short-term effects of sulfide's addition, pH in acidic conditions and the temperature below optimum values of reactor's functioning, as well as its capacity to recover after exposed. The reactor showed sensitivity to small variations on pH. Losses in ammonia removal efficiency were observed when the reactor operated at pH values lower than 6.71 ± 0.01. The tested sulfide concentrations, i.e. 0.1 and 0.25 mg S L -1 , have caused inhibitory effect. The temperature range of 36 - 25 o C did not compromised the reactor's performance.
Título em inglês do resumo, difere da ficha catalográfica, folha de aprovação e termo de autorização anexado ao formulário 7, enviado por e-mail, pelo departamento em 21/03/2016.
14
Berry, Alice L. "The effects of shear and mixing on a continuously-fed stirred tank reactor for aerobic, biological wastewater treatment". Thesis, Cranfield University, 2002. http://dspace.lib.cranfield.ac.uk/handle/1826/7984.
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Treatment of domestic wastewater in a 9 L well defined conventional biotechnology type reactor was investigated over a range of stirrer speeds (8.3 to 16.7 s-1) and retention times (8 to 12 h). Parameters of reactor oxygen transfer coefficient and shear were found to be close to conditions used for pure cell culture in industrial applications rather than typical wastewater treatment conditions. The major treatment effects measured were carbonaceous load removal and nitrification. Carbonaceous load removal was found to be highest at low stirrer speeds with short retention times. Ammonia removal was greatest at stirrer speeds of 15 s-1 with 12 h retention time. Most of the ammonia was converted to nitrite, this agreed with reports in the literature of temperature; retention time and free ammonia inhibition promoting nitrite build up. Specific nitrification rates of up to 35 mg(N)g-1h-1 (at 15 s-1 10 h retention time) were achieved in the reactor, found to be close to those observed in pure culture experiments. An inverse correlation was observed between ammonia and CBOD5 removal. The temperature increased with stirrer speed and also had a strong effect in the nitrification rate. The interaction between temperature and stirrer speed was investigated using a control unstirred reactor and multiple linear regression technique. It was found that while the temperature and stirring were correlated, separate effects could be discerned. The stirrer effects were further investigated by varying the impeller type. Tip speeds were matched to the disk turbine for a low and a high shear impeller. The lower shear LE20 impeller gave promising results that required a much lower power input to achieve the treatment. Finally an anoxic reactor was added to denitrify the stirred tank effluent. It was found to successfully denitrify when sufficient nitrite and nitrate were supplied by the stirred tank. The combination of a stirred nitrifying tank followed by a denitrifying stage could make be an attractive alternative wastewater treatment method providing the stirred tank power requirements can be reduced.
15
Kotsiopoulos, Athanasios. "Development of an unsteady state model for the tank bioleaching of sulphide mineral concentrates in flow reactor systems". Doctoral thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/10849.
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Includes bibliographical references.In this thesis, it is hypothesized that in bioleaching flow reactor systems, high reaction rate regions exist that can be maintained by application of biological stress trajectories. Reactor models are developed for the purpose of optimising plant operation, understood here as maximising the production rate. Complicating this attempt are a) the non-linear dynamics associated with the kinetics and b) the primary reaction's being multiphase. Mathematical models are developed to establish which particle parameters are necessary to describe reactor performance using the method of segregation. The models are distinguished by the combination of either particle residence time or age and/or particle size distributions. The models evaluated at steady state are validated against pilot plant data obtained from the Fairview Mine in South Africa and were found to be in good agreement with the data. As the model was developed using a segregation approach and thus incorporates age distributions in the model formulation, the model could be extended to unsteady state operation.
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Sarah, Oddy. "Effect of Phase-Contacting Patters and Operating Conditions on Gas Hydrate Formation". Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31414.
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Research into hydrate production technologies has increased in the past years. While many technologies have been presented, there is no consensus on which reactor design is best for each potential application. A direct experimental comparison of hydrate production technologies has been carried out in between a variety of reactor configurations at similar driving force conditions. Three main reactor types were used: a stirred tank, a fixed bed and a bubble column
and compared different phase contacting patterns for the stirred tank and bubble column.
In the initial phase of hydrate formation in a stirred tank, formation was mass and heat transfer limited at the lower stirring speed, and heat transfer limited at the higher stirring speed. After more than 10% of the water had been converted to hydrate, formation was mass transfer limited regardless of the other conditions. Neither the use of a gas inducing impeller, nor a 10 wt% particle slurry significantly affected hydrate formation rates; however, the particle slurry
did lower the induction time. Due to the poor scale-up of impeller power consumption in a stirred tank, a semi-batch fixed bed was studied since it does not require any power input for mixing. The significantly slower rates of formation observed in the semi-batch fixed bed, as well as the lost reactor capacity to particles, mean that this type of system would require a much larger reactor.
Faster volume and power normalized rates of hydrate formation were observed in the bubble column than in a stirred tank at similar mass transfer driving force conditions. Higher conversions of water to hydrate were observed in the bubble column because mixing was accomplished by bubbling gas from the bottom rather than by an impeller. The highest conversions of water and gas were achieved during a later stage of accelerated hydrate formation, indicating an optimal hydrate fraction for continuously operated bubble column reactors. The second stage of hydrate formation occurred more frequently at higher gas flowratess. Therefore, the increased water conversion and single-pass gas conversion justify the
increased energy input required by the higher gas flowrate. Balancing the rates of mass transfer and heat removal was also critical for optimal bubble column as insufficient mass transfer would result in a lower rate of formation and insufficient heat transfer would cause previously formed
hydrates to dissociate. The addition of 10wt% glass beads to the reactor promoted hydrate formation; however, it did not do so sufficiently to make up for the loss in reactor capacity or the increased energy requirement.
17
Pinheiro, Iara Rebouças. "Estudo da produção do antibiótico antitumoral retamicina em biorreatores com células imobilizadas de Streptomyces olindensis ICB20". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-09012008-173427/.
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O objetivo deste trabalho foi estudar a produção do antitumoral retamicina por células imobilizadas de Streptomyces olindensis ICB20 em biorreatores. A imobilização das células foi conseguida após uma etapa inicial de cultivo em erlenmeyers (reativação e pré-imobilização) e posterior envolvimento em gel, utilizando-se alginato de cálcio 3%; as esferas produzidas tinham diâmetro médio de 3,0 ± 0,2 mm. Foram utilizados neste trabalho os biorreatores tipo cesta (2,4 L de volume útil) e coluna de bolhas (1,6 L de volume útil), efetuando-se cultivos em batelada simples, bateladas repetidas e contínuos, visando-se uma comparação dos diferentes sistemas empregados. Também foram realizados alguns cultivos com células livres, a fim de efetuar uma comparação com os sistemas com células imobilizadas nos diferentes biorreatores. Os ensaios consistiram em empregar diferentes condições de agitação (300 e 500 rpm) e aeração (0,4 e 1 vvm) para o biorreator cesta em sistema com células imobilizadas, assim como diferentes vazões de aeração no biorreator coluna de bolhas (1, 2 e 3 vvm). Os cultivos em bateladas repetidas e contínuos foram operados a partir das melhores condições obtidas nos cultivos descontínuos. Foram aplicadas nos sistemas contínuos com células imobilizadas, as vazões específicas de alimentação de 0,05 e 0,2 h -1 no biorreator cesta e vazões de 0,015 a 0,05 h -1 no biorreator coluna de bolhas. A comparação entre os sistemas com células livres e imobilizadas mostrou que as limitações difusionais afetaram significativamente as cinéticas dos ensaios com células imobilizadas, considerando-se apenas uma batelada. A operação do biorreator cesta em sistema de bateladas repetidas apresentou os maiores valores de produção da retamicina (em torno de 1,5 a 1,7 UA), porém sua operação foi possível por apenas três bateladas. O sistema contínuo operado com vazão específica de alimentação de 0,03 h-1, com células imobilizadas no biorreator coluna de bolhas, mostrou ser o mais adequado dentre todos os ensaios realizados com células imobilizadas, apresentando estabilidade na produção, em torno de 0,8 UA, durante 96 horas de alimentação (cerca de três tempos de residência).The purpose of this study was to investigate the production of the antitumor antibiotic retamycin by immobilized cells of Streptomyces. olindensis ICB20 in bioreactors. Cells were immobilized by entrapment in Ca-alginate gel (3%) after being grown in Erlenmeyers (reactivation and pre-immobilization cultures). The average diameter of the Ca-alginate beads was 3.0 ± 0.2 mm. Aiming to compare different cell systems, immobilized cell cultures were carried out in a 2.4L working volume basket-type stirred tank reactor (BSTR) and a 1.6 L working volume bubble column reactor (BCR) in batch, repeated-batch and continuous modes. Free cell suspension cultures were also performed and the results obtained compared to those in immobilized cell systems. Different agitation rates (300 and 500 rpm) and air flow rates (0.4 and 1.0 v.v.m.) were employed in the BSTR immobilized cell experiments.The BCR cultures were conducted at 1.0, 2.0 and 3.0 v.v.m. The optimal operating conditions for the batch mode were used in the repeated-batch and continuous cultures. Immobilized cells were grown in continuous mode at feed dilution rates of 0.05 and 0.2 h-1 in the BSTR and at 0.015 and 0.05 h-1 in the BCR. The comparative evaluation of the batch cultures with free and immobilized cells showed that diffusion limitations had affected the kinetics of cell growth and retamycin production in the immobilized cell systems. The highest average values of retamycin content (from 1.5 to 1.7 AU) were achieved in repeated batch cultures conducted in the basket-type reactor (BSTR) in spite of a limited number of batches (3 batches). Of all the systems, the continuous cell immobilized culture carried out in the BCR at a dilution rate of 0.03 h-1 proved to be the most adequate for retamycin production as retamycin levels remained stable (around 0.8 AU) over 96 hours (about 3 residence times).
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Muga, Julius N’gon’ga. "Design and implementation of IEC 61499 standard-based nonlinear controllers using functional block programming in distributed control platform". Thesis, Cape Peninsula University of Technology, 2015. http://hdl.handle.net/20.500.11838/2381.
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Thesis (DTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.Majority of the industrial systems encountered are significantly non-linear in nature, so if they are synthesised and designed by linear methods, then some of salient features characterising of their performance may not be captured. Therefore designing a control system that captures the nonlinearities is important. This research focuses on the control design strategies for the Continuous Stirred Tank Reactor (CSTR) process. To control such a process a careful design strategy is required because of the nonlinearities, loop interaction and the potentially unstable dynamics characterizing the system. In these systems, linear control methods alone may not perform satisfactorily. Three different control design strategies (Dynamic decoupling, Decentralized and Input-output feedback linearization controller) are proposed and implemented .in the Matlab/Simulink platform and the developed strategies are then deployed to the design of distributed automation control system configuration using the IEC 61499 standard based functional block programming language. Twin CAT 3.1 system real-time and Matlab/Simulink (www.mathworks.com) environment are used to test the effectiveness of the models The simulation results from the investigation done between Simulink and TwinCAT 3 software (Beckhoff Automation) platforms in the case of the model transformation and closed loop simulation of the process for the considered cases have shown the suitability and the potentials of merging the Matlab/Simulink control function blocks into the TwinCAT 3.1 function blocks in real-time. The merits derived from such integration imply that the existing software and software components can be re-used. This is in line with one of the IEC 6144 standard requirements such as portability and interoperability. Similarly, the simplification of programming applications is greatly achieved. The investigation has also shown that the integration the of Matlab/Simulink models running in the TwinCAT 3.1 PLC do not need any modification, hence confirming that the TwinCAT 3.1 development platform can be used for the design and implementation of controllers from different platforms. Also, based on the steps required for model transformation the between the Matlab/Simulink to the TwinCAT 3 functional blocks, the algorithms of the control design methodologies developed, simulation results are used to verify the suitability of the controls to find whether the effective set-point tracking control and disturbance effect minimisation for the output variables can be achieved in real-time using the transformed Simulink blocks to the TwinCAT 3 functional blocks, then downloaded to the Beckhoff CX5020 PLC for real-time execution. Good set-point tracking control is achieved for the MIMO closed loop nonlinear CSTR process for the considered cases of the developed control methodologies. Similarly, the effects of disturbances are investigated. TwinCAT functional modules achieved good set-point tracking with these disturbances minimization under all the cases considered.
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Ballestas, Castro Dairo. "Études d’un réacteur micro-ondes monomode de type cuve agitée pour la synthèse chimique et proposition d’une méthodologie d’extrapolation". Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10114/document.
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Le chauffage par micro-ondes (MO) est employé depuis plus de 20 ans dans nombreux laboratoires pour l’activation de réactions en synthèse chimique. Il existe un débat sur l’existence d’effets MO sur la vitesse des réactions puisque des augmentations des vitesses des réactions ont été parfois observées. Des caractéristiques du chauffage MO peuvent être intéressantes pour l’intensification des procédés mais cette technique a rarement fait l’objet de productions à grande échelle. Peu de méthodes d’extrapolation de ces applications ont été proposées et celles qui existent sont purement empiriques. Nous avons voulu établir une méthodologie d’extrapolation de réacteurs MO en nous servant d’observations expérimentales fiables. La méthodologie des travaux a d’abord consisté au choix d’une réaction cible pour nos études : l’estérification de l’acide acétique avec le pentanol catalysée par une résine acide d’échange ionique. Nous avons conçu et construit un réacteur agité avec application monomode des MO. Des études dans le pilote ont montré le comportement hydrodynamique parfaitement agité du réacteur, la reproductibilité et la haute efficacité du chauffage. De plus, aucun gradient de température dans le réacteur n’a été mis en évidence. Des tests chimiques sous MO en réacteur fermé et en continu, ainsi qu’en milieu peu polaire ont montré que l’application des MO n’a pas eu d’influence sur la cinétique de la réaction cible. Finalement, nous avons développé une procédure d’extrapolation de réacteurs micro-ondes de type cuve agitée, qui est basée sur l’absence d’effet MO sur la chimie et sur le contrôle des zones chaudes dans le réacteurMicrowave (MW) assisted organic synthesis has been employed in many laboratories since more than 20 years. There is a controversy concerning the effects of MW on the kinetics of reactions since some enhancement of reaction rates have been observed. While MW heating advantages could be of interest for processes intensification, this technique has rarely been employed for large-scale productions. Scaling-up methods are rare and the existed techniques are generally empirical. The aim of our project is to propose a methodology for the extrapolation of MW reactors, using experimental reliable observations. Our research strategy has enabled us the choice of the target reaction to be carried out under MW irradiation: the esterification of acetic acid with pentanol over an acidic cation-exchange resin. A stirred reactor with MW single mode application was designed and constructed. Studies on the pilot have showed the perfectly stirred hydrodynamic behaviour of the reactor, the stability and the high heating efficiency. Moreover, no thermal gradients in the reactor have been observed. Tests in the reactor operated in batch and continuous mode, as well as in weak polar media, showed that there is no influence of MW heating on the kinetics of the target reaction. Finally, a guideline for the scaling-up of MW reactors was developed, based on the absence of MW effects on the reaction kinetics and on the control of hot zones in the reactor
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Ambriano, John Robert. "The development of a continuous stirred tank membrane reactor for determining an accurate rate equation for the production of citric acid by Saccharomycopsis lipolytica". Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/11898.
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Cameron, Rory. "Bioleaching of low-grade nickel sulphide ore at elevated pH". Thesis, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19784.
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This thesis examines the bioleaching of six different Canadian nickel sulphide ores at pH levels above what is generally considered optimum (~ 2). The majority of work discussed in this thesis was conducted with a low-grade metamorphosed ultramafic nickel sulphide ore from Manitoba, Canada (Ore 3), which is not currently exploitable with conventional technologies. The ore contains 21% magnesium and 0.3% nickel. Nickel is the only significant metal value, and is present primarily as pentlandite. A substantial fraction of the magnesium is present as the serpentine mineral lizardite, making processing difficult with conventional pyro- and biohydrometallurgical techniques. The work with this ore has two equally important objectives: to minimize magnesium mobilization and to obtain an acceptable level of nickel extraction. Batch stirred-tank bioleaching experiments were conducted with finely ground ore ( 147 µm) with temperature and pH control. The first phase of experimentation examined the effect of pH (2 to 6) at 30 °C, and the second phase examined all combinations of three pH levels (3, 4 and 5) and five temperatures (5, 15, 22.5, 30, and 45 °C).
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Olughu, Williams C. "The systematic consideration of the large-scale fed-batch fermentation inhomogeneities using a genetically modified C. glutamicum strain as a model organism". Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/34284.
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The loss of efficiency and performance of bioprocesses on scale-up is well known, but not fully understood. This work addresses this problem, by studying the effect of some fermentation gradients (pH, glucose and oxygen) at a larger scale in a bench-scale two compartment reactor (PFR + STR) using the cadaverine-producing recombinant bacterium, Corynebacterium glutamicum DM1945 Δact3 Ptuf-ldcC_OPT. The initial scale down strategy increased the magnitude of these gradients by only increasing the mean cell residence time in the plug flow reactor (τ_PFR). The cell growth and product related rate constants were compared as the τ_PFR was increased; differences were significant in some cases, but only up to 2 min residence time. For example, losses in cadaverine productivity when compared to the control fed-batch fermentation on average for the τ_PFR of 1 min, 2 min and 5 min were 25 %, 42 % and 46 % respectively. This indicated that the increasing the τ_PFR alone does not necessarily increase the magnitude of fermentation gradients. The new scale-down strategy developed here, increased the magnitude of fermentation gradients by not only increasing the τ_PFR, but also considering the mean frequency at which the bacterial cells entered the PFR section (f_m). The f_m was kept constant by reducing the broth volume in the STR. Hence, the bacterial cells also spent shorter times in the well mixed STR, as the τ_PFR was increased (hypothesised as giving the bacterial cells less time to recover the non-ideal PFR section of the SDR). On adoption of this strategy cadaverine productivity decreases for the τ_PFR of 1 min, 2 min and 5 min were 25 %, 32 % and 53 % respectively. Thus, highlighting that loss in performance is most likely to occur as the magnitude of heterogeneity within the fermentation environment increases. However, Corynebacterium glutamicum DM1945 Δact3 Ptuf-ldcC_OPT did show some resilience in its biomass productivity. It was only marginally affected in the harshest of conditions simulated here.
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Jambi, Ebtihaj J. "Comparative studies on the cultivation of Xanthomonas campestris in submerged culture for the production of xanthan using the traditional industrial stirred tank reactor and a novel oscillatory baffled bioreactor". Thesis, University of Strathclyde, 2012. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=18713.
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Xanthan is a well-known extracellular polysaccharide, produced by a Gram negative bacterium Xanthomonas campestris (X. campestris) under aerobic conditions. Solutions of xanthan exhibit high viscosities and non-Newtonian behaviour even at low concentrations. This biopolymer has a wide range of valuable commercial and industrial applications, for example; it can be used as a food thickening agent and a stabilizer in some other industries. Traditionally the production of xanthan has predominantly been performed in stirred tank fermenter (STR). This study sought to compare the cultivation of the bacterium, X. campestris for the production of the viscous biopolymer xanthan gum in two different reactor systems, a novel oscillatory baffled reactor (OBR) and the conventional industry workhorse, the stirred tank reactor (STR). Overall biopolymer production occurred at similar rates in the well stirred and aerated STRs, albeit at the cost of higher energy inputs for mixing and aeration. Despite much previous literature promoting the use of the OBR for transporting and reacting very viscous systems, this was the first actual study attempting to investigate the use of the OBR for a highly viscous non-Newtonian fermentation process. The experimental results show that xanthan production was similar in the OBR than in the STR, the OBR is however readily suitable for the cultivation of xanthan. The probable reasons for the inability of the OBR to match the production rates of the STR may well lie in the complex nature of this fermentation process. Unlike a previous study on pullulan production (Gaidhani 2004) where the OBR outperformed the STR, X. campestris initially needs high oxygen transfer rates and the OBR, although it provides good bulk mixing and low energy consumption, seemed unable to equal the STR in this respect, especially in a very viscous system. The result shows that xanthan production in the OBR was similar to the equivalent process in the STR. In order to attempt to improve the OBR a number of technical modifications were made including a novel sparger design to improve gas dispersal. These were not successful in improving xanthan production. Similarly, attempts to achieve improvements via wider amplitude ranges led to damage to the equipment. The conclusion was that significant improvements to the physical robustness of the OBR were necessary before it could be successfully used to process highly viscous bio-fluids.
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Steyer, Christiane Verfasser], Kai [Akademischer Betreuer] [Sundmacher, Jürgen [Akademischer Betreuer] Tomas i Michael [Akademischer Betreuer] Mangold. "Precipitation of barium sulfate in a semi-batch stirred tank reactor : influence of feeding policy on particle size and morphology / Christiane Steyer. Betreuer: Kai Sundmacher ; Jürgen Tomas ; Michael Mangold". Magdeburg : Universitätsbibliothek, 2012. http://d-nb.info/105391430X/34.
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Pinot, Jordanna. "Caractérisation du micromélange par la réaction iodure-iodate en milieu visqueux". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0140/document.
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Le micromélange, ou mélange à l'échelle moléculaire, a une influence déterminante sur la qualité des produits, la sélectivité, et le rendement de réactions d'importance industrielle comme les réactions de polymérisation. A l'heure actuelle, les systèmes chimiques existants sont bien adaptés à l'étude du micromélange de produits faiblement visqueux, mais il n'existe pas de méthode simple et opérationnelle pour les fluides plus visqueux. Inscrite dans le cadre du projet ANR PROCIP, l'étude a consisté à mettre en place une nouvelle méthode de quantification de l'efficacité du micromélange en milieu visqueux dans des réacteurs agités. La méthode utilisée s'inspire d'un système chimique basé sur deux réactions concurrentes, le système de réaction test iodure-iodate, dont la sélectivité d'un des produits est une mesure de l'efficacité du micromélange. L'approche propose un nouveau protocole basé sur le choix d'un tampon phosphate et l'utilisation de l'HydroxyEthylCellulose (HEC, 720 000 g/mol) comme agent viscosifiant inerte, qui possède un fort pouvoir viscosifiant permettant d'augmenter significativement la viscosité sans en ajouter plus de 1 % en masse dans le milieu. Des essais de caractérisation du micromélange en réacteur agité ont mis en évidence le ralentissement du micromélange au fur et à mesure que la viscosité augmente pour des pourcentages en HEC inférieurs à 0,5 %. Par contre, au-delà de 0,5 %, une « amélioration » du micromélange a été observée dans une large gamme de conditions expérimentales (différentes concentrations de réactifs, positions de l'injection, vitesses d'agitation et mobiles d'agitation). Plusieurs causes potentielles ont été formulées en vue d'expliquer ce phénomène et les cinétiques des réactions mises en jeu ont également été étudiées en présence de l'agent viscosifiant HEC et s'avèrent être inchangées. Enfin, une étude des interactions possibles entre les espèces iodées et l'HEC a été réalisée pour étudier l'existence d'une réaction parasite qui pourrait expliquer les résultats obtenusMicromixing, or mixing at the molecular scale, has a decisive influence on product quality, selectivity and yield of industrially important reactions such as polymerization reactions. Currently, the existing chemical systems are well suited to the study of micromixing of low viscosity products, but no reliable characterization method exists for highly viscous media. As a part of the ANR project PROCIP, the study consisted in developing a new method to quantify the efficiency of micromixing in viscous media in stirred reactors. The method used is inspired by a chemical system based on two competitive reactions, the iodide-iodate test reaction system whose selectivity of a product is a measure of the micromixing efficiency. The approach proposes a new protocol based on a phosphate buffer and the use of HydroxyEthylCellulose (HEC, 720,000 g / mol) as an inert viscosifying agent, enabling to significantly increase the viscosity without adding more than 1 % by mass in the medium. Characterization of micromixing in a stirred reactor showed the slowing down of micromixing as viscosity increases for percentages of HEC below 0.5 %. By contrast, above 0.5 %, an "improvement" of micromixing has been observed in a wide range of experimental conditions (different concentrations of reactants, injection positions, stirring speeds and impellers). Several possible causes have been made to explain this phenomenon unexpected and the kinetics of the reactions involved were also studied in the presence of the viscosifying agent HEC and appeared to be unchanged. Finally, a study of possible interactions between iodine species and HEC was performed to study the existence of a secondary reaction which could explain the results
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Herklotz, Anne Maria. "Entwicklung eines teilkontinuierlichen Thermolyseverfahrens zum rohstofflichen Recycling von polyolefinischen Kunststoffabfällen in einer Rührkesselkaskade". Doctoral thesis, Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-213000.
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In der vorliegenden Arbeit wird die Konzeptionierung und die Realisierung eines teilkontinuierlichen Thermolyseverfahrens zur rohstofflichen Verwertung von Polyethylen- und Polypropylenabfällen beschrieben.
Die Ausführung in der zweistufigen Rührkesselkaskade gewährleistete dabei die Trennung der Prozessschritte Schmelzen sowie Cracken der Einsatzmaterialien, woraus ein Thermolyseöl hervorging, welches weitestgehend frei von den Verunreinigungen aus den Abfällen war. Das Thermolyseöl wies eine Zusammensetzung aus Benzin- und Dieselkomponenten auf und erfüllte einige entscheidende Kraftstoffkriterien.
Zur Senkung der qualitätsmindernden Olefingehalte wurden in einem weiteren Teil dieser Arbeit Untersuchungen zur heterogen-katalysierten Hydrierung der Siedeschnitte im Schüttgutreaktor und im Rührautoklav durchgeführt. Dabei konnten die Olefingehalte durch den Einsatz eines Palladium-Platin-Trägerkatalysators sowie durch einen Nickel-Gerüstkatalysator maßgeblich gesenkt werden. Als unerwünschtes Nebenprodukt des Thermolyseprozesses resultierte ein geringer Anteil Koks, welcher in der Schmelze akkumulierte und sich teilweise an der Reaktorwand ablagerte. Die entstandenen Mengen wiesen eine Abhängigkeit von der Prozesstemperatur und -dauer auf und mussten aus dem Prozess geschleust werden. Als weitere Nebenprodukte traten ein leichtflüchtiges Spaltgas sowie ein Sumpfrückstand auf.
Darüber hinaus wurde gezeigt, dass die aufzuwendende Energie für den Thermolyseprozess durch die Energiegehalte der Nebenprodukte gedeckt werden kann. Neben dem Einsatz als Kraftstoff empfahl sich das Thermolyseöl aufgrund seiner physikalischen und chemischen Eigenschaften gerade im Hinblick auf einen nachhaltigen Umgang mit Ressourcen als beachtenswerter Ersatz für fossiles Rohöl.
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Laus, Raffaele. "Confronto tra configurazioni di bioreattori anaerobici per la produzione di biometano da oli alimentari esausti". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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Ad oggi il riutilizzo degli oli da cucina esausti (WCO) è prevalentemente indirizzato alla produzione di biodiesel dato che i tempi di digestione anaerobica della componente lipidica sono molto più lunghi di quanto non possano essere i processi chimici di transferificazione per la produzione di biodiesel. Nel presente elaborato si è, tuttavia, cercato di valorizzare i WCO per la produzione di biogas e nello specifico biometano andando a valutare la validità o meno di un approccio diverso da tradizionali sistemi di digestione anaerobica. Si è studiato nello specifico una tipologia di sistema anaerobico con funzionamento simile all’più comune Air-lift a cui si è dato il nome di Gas-lift in cui a determinare la miscelazione è lo stesso biogas generato dalla digestione anaerobica che avviene all’interno del reattore. Questo sistema è stato messo a confronto con un altro sistema già noto nell’ambito della digestione anerobica ovvero un Continuous Stirred Tank Reactor (CSTR) di dimensioni più ridotte ma con le stesse proporzioni di WCO, terreno d’idratazione (HM) e inoculo (Rhodococcus opacus). Si sono svolte tre sperimentazioni differenti due delle quali realizzate in condizioni batch e una terza ed ultima fase realizzata in semi-continuo mediante il prelievo/immissione di un certo quantitativo HM e immissione di nuovo WCO. Il sistema Gas-lift così realizzato ha i duplice scopo di avvicinare la componente batterica anaerobica all’unica fonte di carbonio disponibile, ovvero il WCO, che in quanto costituito da lipidi crea una situazione bifasica separata dalla soluzione e al contempo di favorire la miscelazione della fase liquida. Si sono effettuate durante il periodo di studio analisi relative alla quantità e alla composizione del biogas prodotto e analisi di Chemical Oxygen Demand (COD), N-NH4 e acidi grassi volatili (VFAs) al fine di avere un inquadramento generale dei processi di degradazione in corso all’interno di entrambi i sistemi anaerobici.
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Gomes, Fernanda Cavalcante. "Decantação acelerada: alternativa para o tratamento de vazão excedente de esgoto - estudo na ETE Martim de Sá (Caraguatatuba/SP)". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3147/tde-17082010-101003/.
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Este estudo foi motivado pela necessidade de se tratar o excesso de vazão afluente às estações de tratamento de esgoto, que ocorre em dias de chuvas intensas. A hipótese central deste estudo é a de que a adoção de processo físico-químico para o tratamento de esgoto excedente diluído, pode ser vantajosa em relação ao aumento da capacidade com a ampliação dos sistemas exclusivamente biológicos. A pesquisa foi desenvolvida na ETE Martim de Sá da SABESP, localizada em Caraguatatuba/SP, onde o esgoto é tratado por lodos ativados em bateladas sequenciais. Estudou-se a variação da vazão de esgoto afluente na época de chuvas, bem como o funcionamento das bateladas. Além disso, foi avaliado o emprego da coagulação, floculação e sedimentação em decantador laminar para tratar o excesso de vazão com aplicação de sulfato de alumínio, cloreto férrico e polímero catiônico em uma estação piloto, após a realização de ensaios em escala de bancada em aparelho de Jar Test. O monitoramento da vazão afluente mostrou que em dias de chuvas e com ocorrência de desvios, a vazão máxima foi 220 L/s, ou seja, até 6 vezes maior que a vazão média de tempo seco. Para esta situação, o processo físico-químico pode tornar-se uma alternativa promissora, devido à sua capacidade de trabalho sob altas vazões em instalações de menor porte. Nos ensaios para se avaliar o tratamento físico-químico utilizou-se esgoto bruto pertencente a duas faixas de DBO: 50 e 100 mg/L e taxa de aplicação superficial no decantador de 76,82 m³ / m² / dia. A melhor dosagem de produto químico utilizada para tratar o esgoto bruto da faixa de DBO igual a 50 mg/L foi 40mg/L de cloreto férrico mais 0,5mg/L de polímero catiônico resultando em efluentes com DBO média de 26mg/L. Para o esgoto bruto da faixa de DBO igual a 100 mg/L a melhor dosagem foi a de 60mg/L de cloreto férrico, com DBO média dos efluentes igual a 44mg/L. Para esta faixa de trabalho é recomendável prever a aplicação de polímero. Por esta pesquisa concluiu-se que é possível atender aos limites legais de qualidade do esgoto tratado com o emprego do tratamento físico-químico, além disso produziu elementos importantes para subsidiar a avaliação econômica para a implantação desta tecnologia em paralelo ao sistema de lodo ativado nas situações de sobrecarga hidráulica. No entanto, a análise do fluxograma do funcionamento da estação com o processo de lodos ativado em bateladas, indicou que é possível efetuar o tratamento da vazão de 220 L/s pelo processo biológico. Assim, é recomendável a implantação do tratamento físico-químico somente se, após a realização do teste em escala real do funcionamento das bateladas com a vazão de 220 L/s, o tratamento biológico não atender aos padrões estabelecidos.This study was motivated by the need to treat high wastewater influent exceeding in sewage treatment plants, which occurs on days of heavy rain. The central hypothesis of this study is that the physical-chemical process to treat dilute sewage overflow, it can be advantageous with respect to increased capacity and expansion of biological systems. The research was conducted in ETE Martim de Sá (SABESP), located in Caraguatatuba / SP, where the sewage is treated by sequencing batch reactor. It was studied the variation of the flow of wastewater during the rainy season, and the operation of the batch. Furthermore, it was evaluated the use of coagulation, flocculation and sedimentation in plate settler with application of aluminium sulfate, ferric chloride and cationic polymer in a pilot plant, after the testing of bench scale apparatus in Jar Test. Monitoring the inflow showed that on days of rainfall and bypass, the maximum flow was 220 L/s, up to 6 times the dry weather average flow. For this situation, the physico-chemical process may become a promising alternative, due to its ability to work under high flow rates in smaller facilities. In tests to evaluate the physical-chemical treatment was used two kinds of raw sewage: 50 and 100 mg/L BOD, overflow rate used in the plated settling tank was 76.82 m³/m² / day. The best dosage of chemical used to treat the raw sewage BOD of 50 mg/L was 40 mg/L ferric chloride plus 0.5 mg/L of cationic polymer, resulting in average effluent with BOD of 26 mg/L. For the raw sewage of the range BOD of 100 mg/L, 60 mg/L ferric chloride was the best dosage with an average BOD of effluent equal to 44 mg/L. For this range of work is recommended to provide for the application of polymer. This research concluded that it is possible to comply with the legal standard of treated sewage with physical-chemical treatment, also produced evidence that can help in the economic evaluation for the implementation of this technology in parallel with the activated sludge system in hydraulic overload situations. However, analysis of the flow diagram of operation of the station with the sequencing batch reactor, indicated that it is possible to make the treatment of flow of 220 L/s by the biological process. Therefore, is recommend the implementation of physical-chemical treatment only if after the test-scale operation of the batches with the flow rate of 220 L/s, the biological treatment doesn\'t meet the established standards.
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Panda, Kishora Kumar. "Ozone mass transfer and reaction in In situ and stirred tank reactors /". Search for this dissertation online, 2005. http://wwwlib.umi.com/cr/ksu/main.
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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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Canatas, Aristote. "Le reacteur agite discontinu repetitif : automatisation, applications en chimie fine". Paris 6, 1987. http://www.theses.fr/1987PA066122.
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Le nouveau reacteur de taille plus petite permet de fonctionner avec une introduction des reactifs, une regulation de temperature, regulees de facon discontinue et repetitive. On etudie son automatisation a l'echelle du laboratoire et a l'echelle pilote. Trois reactions exothermiques et rapides sont analysees : preparation du benzoate de sodium a partir de l'acetophenone ou de benzaldehyde par oxydation, l'hydrolyse de l'ethyleneacetal du benzaldehyde, et une reaction de diels alder
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Edwiges, Thiago. "Biodigestão anaeróbia de resíduos vegetais provenientes de central de abastecimento". Universidade Estadual do Oeste do Paraná, 2017. http://tede.unioeste.br/handle/tede/3029.
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The economical development and urbanization process have contributed to the increase in solid waste generation and problems related to final disposal. Thus, the National Solid Waste Policy reinforces treatment in order to improve efficiency in the management of solid waste as one of its priorities and stimulates to recover and use energy. Anaerobic digestion has been suggested as a promising approach to the treatment of organic fraction of solid waste, mainly because it represents an opportunity to reduce environmental pollution and minimizes impacts concerning the energy crisis. So, this trial aimed at evaluating FVW biogas potential, collected in a wholesale market (Unit from Foz do Iguaçu/PR) through batch and semicontinuous tests. Fruits and vegetables trading from that unit generates approximately 70,500 t year-1, with 2,800 kg d-1 solid waste, composed of almost 85% organic matter. The influence of chemical composition of twelve FVW different samples with different compositions on biochemical methane potential (BMP) was analyzed. The BMP ranged from 288 LN CH4 kg VS-1 to 516 LN CH4 kg VS-1, with significant statistical differences among means. This was explained by in the waste chemical composition over time. BMP variation was most strongly correlated for lipid content and high calorific values (HCV). Linear regression analyses were carried out to develop statistical models to predict as fast as possible methane potential of this kind of waste. The models were analyzed according to chemical compounds and HCV based on simple and multiple regression. The model with the best statistical metrics included lipid, protein, cellulose, lignin, and HCV, with a 92.5% R² and lignin content negatively correlated to BMP. Since HCV and lipids were strongly correlated, and because HCV can be determined more rapidly than chemical composition, HCV may be useful for predicting BMP. In addition to batch tests, the performance of anaerobic digestion was also investigated in a semicontinuous mode using a FVW mixture as a single substrate. The performance of a continuous stirred tank reactor (CSTR) was monitored along with the gradual increase of organic loading rates (OLR) from 0.5 gVS L–1 d–1 to 5.0gVSL–1d–1. BMP of FVW used as a feedstock to CSTR was 370 LN CH4 kg VS-1 with 81% biodegradability. During the whole trial pH was stable and there was an adequate level of buffering capacity in the system. Volumetric biogas production (LN biogas L–1 d–1) increased linearly (R² = 94.4%) according to OLR increase. On the other hand, the specific methane production (LN CH4 kg VS-1) has registered the best performance at an OLR of 3.0 g VS L–1 d–1 and 30 days of hydraulic retention time, with 285 LN CH4 kg VS-1 added, reaching 74% of BMP measured by batch tests. A clear accumulation of volatile fatty acids (VFA) was monitored with a decreased specific methane yield was detected with an OLR above 3.0 g VS L–1 d–1.
O crescimento econômico e o processo de urbanização vêm contribuindo para o aumento da geração de resíduos sólidos e problemas relacionados à disposição final. A Política Nacional de Resíduos Sólidos reforça o tratamento com o intuito de melhorar a eficiência quanto ao gerenciamento dos resíduos sólidos no país, como uma de suas prioridades e enfatiza o incentivo à recuperação e ao aproveitamento energético. A biodigestão anaeróbia tem sido apontada como uma abordagem promissora ao tratamento da fração orgânica dos resíduos sólidos, sobretudo por representar oportunidade de reduzir a poluição ambiental e minimizar os impactos da crise energética. Assim, o objetivo deste trabalho foi avaliar o potencial de produção de biogás de resíduos de frutas e hortaliças (RFH) coletados na Central de Abastecimento (CEASA – Unidade de Foz do Iguaçu/PR) a partir de testes em batelada e em regime semicontínuo. A comercialização de frutas e hortaliças da unidade é de aproximadamente 70.500 t ano-1, com geração de resíduos sólidos de 2.800 kg d-1, compostos por aproximadamente 85% de matéria orgânica. A influência da composição química de doze amostras de RFH com diferentes composições sobre o potencial bioquímico de metano (PBM) foi analisada. O PBM dos resíduos variou entre 288 LN CH4 kg SV-1 e 516 LN CH4 kg SV-1, com diferenças estatísticas significativas entre as médias, o que pôde ser explicado pela variação na composição química dos resíduos ao longo do tempo. A variação do PBM foi mais fortemente correlacionada à variação do teor de lipídeos e do poder calorífico superior (PCS). Foram realizadas análises de regressão linear visando desenvolver modelos estatísticos para estimar, de forma mais rápida, o potencial metanogênico deste tipo de resíduo. Os modelos foram analisados considerando os componentes químicos e o PCS a partir de regressão linear simples e múltipla. O modelo com as melhores métricas estatísticas foi obtido considerando lipídio, proteína, celulose, lignina e PCS, com R² de 92,5% e com teor de lignina negativamente correlacionado ao PBM. Como o PCS e os lipídeos apresentaram forte correlação, e como o PCS pode ser determinado, em geral, de forma mais rápida que a composição química, o PCS pode ser considerado um parâmetro útil para a estimava do PBM. Além dos testes em batelada, investigou-se também o desempenho da biodigestão anaeróbia em regime semicontínuo utilizando-se uma mistura de RFH como único substrato. O desempenho de reator de mistura completa (do inglês CSTR) foi monitorado juntamente com o aumento gradativo da carga orgânica volumétrica (COV) de 0,5 g SV L-1 d-1 até 5,0g SV L-1 d-1. O PBM dos RFH utilizado para alimentar o reator foi 370 LN CH4 kg SV-1 com biodegradabilidade de 81%. Durante todo o ensaio o pH se manteve estável e o sistema apresentou boa capacidade tampão. A produção volumétrica de biogás (LN biogás L-1 d-1) aumentou de forma linear (R² = 94,4%) de acordo com aumento da COV. Já a produção específica de metano (LN CH4 kg SV-1) indicou o melhor desempenho com COV de 3,0 g SV L-1 d-1 e 30 dias de tempo de retenção hidráulica, com 285 LN CH4 kg SV-1 adicionados, e atingiu 74% de PBM, medido a partir dos testes em batelada. Observou-se um acúmulo evidente de ácidos graxos voláteis (AGV), com consequente redução da produção de metano a partir da COV acima de 3,0 g SV L-1 d-1.
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Haddadin, Jamal. "Études microbiologiques et cinétiques de la lixiviation bactérienne en réacteurs : effet de différents paramètres physico-chimiques, développement d'un procédé en réacteurs air-lift et lit-fluidisé et application à l'extraction de l'antimoine". Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL063N.
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La lixiviation bactérienne est l'application biotechnologique la plus importante dans l'industrie métallurgique, celle-ci est utilisée pour la récupération des métaux par lessivage, utilisant les capacités que possèdent certains micro-organismes à solubiliser les métaux. Ce travail est divisé en quatre sections: premièrement, nous avons identifié la composition microbiologique de la culture mixte en notre possession. Cette culture mixte est composée de trois populations bactériennes. Deuxièmement, nous avons étudié l'influence de certains paramètres physico-chimiques tels que le pH, la température, la concentration en CO2, le taux de solides et l'ajout de Fe3+ au milieu réactionnel sur la cinétique de la biolixiviation, en culture discontinue. Ces études ont notamment conduit à la détermination d'un pH (1. 75), d'une température (32-37°C) et d'une concentration en CO2 (0,03 et 2% v/v) optimaux pour ce procédé. Troisièmement, nous avons comparé différents systèmes réactionnels (air-lift, lit fluidisé et mécaniquement agité) pour aider au choix d'une future technologie alternative. Notre dernière contribution a porté sur l'étude de la capacité de la culture mixte à oxyder des déchets industriels contenant de l'antimoine, en culture discontinue. Nous avons étudié le rôle important de l'interaction galvanique entre la pyrite et les résidus antimoniés sur la récupération de l'antimoine
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Ribas, Santos Eduardo. "Contribution au diagnostic qualitatif des procédés en intelligence artificielle". Vandoeuvre-les-Nancy, INPL, 1996. http://docnum.univ-lorraine.fr/public/INPL_T_1996_RIBAS_SANTOS_E.pdf.
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L’objectif de la supervision des procédés est de surveiller le fonctionnement d'une unité afin d'assurer la réalisation des objectifs fixés, quels que soient les incidents et perturbations extérieures pouvant intervenir. Il est nécessaire d'avoir une vue générale afin d'être en mesure de réagir et de se focaliser sur les points clés. Dans cette thèse, nous proposons une modélisation de la connaissance du fonctionnement des procédés adaptée à la représentation généralement choisie par les spécialistes lors d'un problème donné: à l'aide d'un modèle complet du fonctionnement normal de l'unité, ils cherchent à trouver des fautes ou des combinaisons de fautes possibles. Les concepts proposés sont fondés sur une réflexion du processus d'acquisition de la connaissance qui permet au spécialiste de progresser dans l'analyse des activités en production. Ce processus inclut la formulation, à partir des modèles mathématiques contenant la description du comportement dynamique ou statique des systèmes, d'un modèle préliminaire, de telle manière qu'un spécialiste, pour améliorer ses connaissances, puisse s'appuyer sur celles composant un modèle crée par un autre spécialiste. Dans un premier temps, nous introduisons une méthodologie pour la définition des connaissances permettant au spécialiste (ou, en général, à un individu placé au sein d'une organisation industrielle) de mieux représenter formellement les descriptions de problèmes afin de reproduire ses raisonnements. Dans un deuxième temps, nous proposons une formulation pour la représentation de la connaissance et pour le diagnostic, ou la construction de la base de connaissances comprend des étapes résultant du processus d'acquisition de la connaissance qualitative. Les concepts sont illustrés par des procédés simples choisis dans le domaine du génie des procédés. Ainsi, le diagnostic qualitatif d'un réacteur idéal continu parfaitement agité est examiné en détail dans le cadre général précédemment étudié
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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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Bauge, Jean-Christophe. "Étude de l'oxydation de composés insaturés en réacteur parfaitement agité et en tube à onde de choc". Vandoeuvre-les-Nancy, INPL, 1998. http://www.theses.fr/1998INPL017N.
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Ce travail s'inscrit dans le cadre d'une meilleure compréhension des mécanismes réactionnels liés à la combustion anormale dans les moteurs à allumage commandé (cliquetis) et à la formation de polluants émis à l'échappement des moteurs diesel (polyaromatiques, suies). L’oxydation de l'isobutène (responsable de l'effet anti-détonant des éthers ajoutés dans les essences) a été étudiée sur deux appareillages complémentaires afin de couvrir un vaste domaine de température. Le réacteur auto-agité par jets gazeux a permis une étude à température modérée (< 640C°), avec identification et analyse quantitative des produits formés par chromatographie en phase gazeuse. Le tube à onde de choc développé récemment au laboratoire a permis une étude à haute température (> 1200C°) par la mesure de délais d'auto-inflammation de mélanges isobutène-oxygène-argon. Un mécanisme réactionnel de 136 réactions a été proposé et validé à l'aide de simulations. L’analyse de ce mécanisme nous a permis de corroborer des résultats déjà publiès sur le caractère inhibiteur de l'isobutène et d'expliquer l'allure auto-accélérée des courbes de consommation des réactifs. L'étude de l'oxydation de quatre précurseurs des suies (l'acetylène, le propyne, l'allène et le 1,3-butadiène) a été réalisée expérimentalement en tube à onde de choc en mesurant des délais d'auto-inflammation de mélanges composé insaturé-oxygéne-argon entre 1011 et 1742 K. Un mécanisme comportant 206 réactions élaboré au laboratoire a été utilisé pour modéliser nos résultats. Des analyses de sensibilité et de vitesse ont permis de dégager les voies réactionnelles prépondérantes : la formation de benzène à notamment été attribuée à la combinaison de deux radicaux propargyle C₃H₃.
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Forrester, Stephanie E. "Hydrodynamics of a gas-inducing impeller". Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362961.
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Thoma, Hubis Suzanne Alice. "Interactions between macro- and micromixing in stirred tank reactors /". [S.l.] : [s.n.], 1989. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=9012.
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Katsanevakis, Athanasios N. "Performance parameters for boiling and gassed stirred tank reactors". Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/844581/.
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The flow field in two-phase boiling and gas-liquid Stirred Tank Reactors, STR, was examined in relation to cavity formation and the associated Relative Power Demand, RPD. The cavitation process has been classified in various stages for both radial and axial impellers operating in boiling water. Experiments done in a boiling reactor of 0.45 m diameter agitated by radial and axial impellers showed that the Relative Power Demand, RPD, can be correlated well with the help of a new formulation of Cavitation number named the Cavagitation number. Differences in RPD between gas-sparged and boiling reactors detected during the experiments imply that there are differences in the mechanism of cavity formation in the two systems. These differences are explained by a consistent physical model. The model was shown to be adequate for most of the features of both boiling and sparged reactors reported in the literature. The flow field in a two-phase boiling reactor has been investigated for the first time in the open literature using Laser Doppler Velocimetry, LDV, in conditions where the RPD was as low as 0.55. Measurements gave important data of the way the flow field is changed by the presence of the second phase which forms stable cavities behind impeller blades. The results also quantified the associated flow field changes in the impeller discharge stream and in the bulk of the reactor. The two-phase flow field was quantitatively described with the help of a simple model derived on the basis of energy balances calculated around the impeller. The model estimates liquid flow rates and mean liquid velocities in the two-phase system using data of the corresponding single-phase system coupled with information about the RPD. Knowledge of the void fraction seems to improve the model predictions which were shown to be in fairly good agreement with the data of mean flow rates that exist in the literature. LDV measurements done in a boiling stirred tank of 0.45 m diameter showed that flow rates can be predicted within an accuracy of around 10% and mean liquid velocities with an accuracy better than 25%, even without taking into account void fraction. Model predictions can be used as input values for numerical codes available for the calculation of flows in two-phase stirred tank reactors. Application of the model is independent of geometry and scale.
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SANTOS, Tarcísio David KOnna Nunes. "Simulação em CFP de um reator CSTR para produção de biodíesel". Universidade Federal de Campina Grande, 2016. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/301.
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TARCISIO DAVID KONNA NUNES SANTOS - DISSERTAÇÃO PPGEQ 2016..pdf: 1645201 bytes, checksum: 6f9773a951b06aacdb26ff5287e21e18 (MD5)Made available in DSpace on 2018-03-20T13:04:38Z (GMT). No. of bitstreams: 1 TARCISIO DAVID KONNA NUNES SANTOS - DISSERTAÇÃO PPGEQ 2016..pdf: 1645201 bytes, checksum: 6f9773a951b06aacdb26ff5287e21e18 (MD5) Previous issue date: 2016-03-23
Este trabalho propôs um modelo matemático para um reator do tipo CSTR (continuous stirred-tank reactor) partindo de dados experimentais da cinética da reação de transesterificação entre o óleo de soja e o acetato de metila, tendo como catalisador uma enzima, a Candida Antartica. Um volume foi proposto para reator para que o tempo médio de residência da mistura reacional fosse suficiente tal que o rendimento esperado, com base nos dados obtidos pelo Matlab®, fosse obtido na saída do reator. O estudo reacional fluidodinâmico foi feito utilizando o software comercial ANSYS® versão 15.0. Duas configurações do reator foram propostas otimização, afim de tornar o processo o mais homogêneo possível, tentando atingir as configurações do reator de mistura perfeita. Os impelidores utilizados foram o tipo pás retas inclinadas e o ripo Ribbon (Âncora), afim de avaliar qual dos impelidores consegue o rendimento satisfatório com menor potência de operação. A potência requerida foi determinada através das equações para misturadores mecânicos, sendo avaliado apenas como variável a rotação das pás.
This work proposes a mathematical model to a reactor of CSTR-type (Continuous Stirred-tank reactor) starting from experimental data of the kinetics of transesterification of soybean oil and methyl acetate, with the catalyst enzyme, Candida Antarctica. A reactor volume was proposed for the average residence time of the reaction mixture was sufficient such that the expected yield, based on data obtained by Matlab, was obtained in the reactor outlet. The reaction fluid dynamic study was done using the commercial software ANSYS® version 15.0. The optimization of the reactor was proposed by comparing the reactor operation with two impellers separately in order to make the process more homogeneous as possible, trying to achieve the perfect blend of reactor configurations. The impellers used were the type inclined straight blades and Ribbon RIPO (Anchor), to determine which of the impellers can the satisfactory performance with lower power operation. The required power was determined by the equations for mechanical mixers, being rated only as a variable rotation of the blades
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Baumlin, Sébastien. "Craquage thermique des vapeurs de pyrolyse-gazéification de la biomasse en réacteur parfaitement auto-agité par jets gazeux". Thesis, Vandoeuvre-les-Nancy, INPL, 2006. http://www.theses.fr/2006INPL041N/document.
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ALes gaz issus des procédés de pyrolyse-gazéification de la biomasse doivent être épurés. Ils contiennent des vapeurs condensables (goudrons), des aérosols, des particules solides fines, des composés soufrés et des métaux alcalins qu’il s’agit d’éliminer avant leur utilisation sur des turbines (production d’électricité) ou comme gaz de synthèse. Les expériences rapportées dans ce travail concernent les vapeurs condensables et leur conversion par craquage thermique. Les vapeurs sont produites par pyrolyse de la biomasse dans un premier réacteur (RP) à 540°C. Elles sont ensuite craquées dans un réacteur parfaitement auto-agité par jets gazeux (RPAA) associé en série avec le RP. Le RPAA fonctionne à plus haute température (550-1030°C) et le temps de séjour de la phase gazeuse dans le craqueur est compris entre 0,1 et 1 s. Tous les produits de réaction (charbon, vapeurs condensables et gaz permanents) sont récupérés et analysés. Le RPAA étant uniforme en température et en concentration, la détermination de constantes de vitesse à temps de séjour donné est assez aisée à partir de bilans de matière en vapeurs et gaz. Des schémas réactionnels globaux rendant compte du craquage des vapeurs en gaz mais aussi de leur possible maturation en composés plus réfractaires sont proposés et leurs constantes de vitesse optimisées à partir des résultats expérimentaux. Ces modèles permettent de simuler le craquage thermique d’une charge type issue d’un gazogène. On détermine les conditions optimales de fonctionnement (température, temps de séjour) du réacteur de craquage qui aboutissent à une concentration en vapeurs condensables la plus faible possible. On comparera ainsi l’efficacité du craquage thermique à celle des autres procédés d’épuration des goudronsPyrolysis and gasification processes give rise to gases containing by-products such as condensable vapors (tars), aerosols, dust, sulfur compounds and inorganics which may considerably lower the efficiency of catalysts (if chemical synthesis is foreseen) or cause severe damages to motors and turbines (in case of electricity production). Hence, efficient gas treatments are needed. The experiments reported in the present work are related to thermal cracking of condensable vapors. These vapors are produced in a first reactor by biomass pyrolysis (PR) at 540°C. They undergo further cracking in a second vessel, a continuous serf stirred tank reactor (CSSTR), assembled in series with the PR. The CSSTR is operated at temperatures ranging from 550 to 1030°C and gas phase mean residence times ranging from 0,1 to 1 s. Reaction products (char, condensable vapors and permanent gases) are recovered and analyzed. Temperature as well as composition are uniform at any point of the CSSTR. Therefore, it is easy to derive values of kinetic constants from mass balances at a given residence time. Global vapor cracking schemes including gas formation as well as possible maturation into more refractory compounds are proposed. Their kinetic constants are optimized from the experimental results. These models are used to simulate the thermal cracking of a typical load flowing out from a gasifier. Optimal operating conditions of the cracking reactor (in terms of temperature and residence time) are determined to reach the lowest condensable vapors concentration. Thus, efficiency of thermal cracking can be compared to other gas treatment processes
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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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Pani, Fatos. "Hydrodynamique et transferts de matiere en reacteurs agites gaz-liquide et gaz-liquide-liquide : application oxydante du cuivre par lix 65n-hs". Paris, ENMP, 1987. http://www.theses.fr/1987ENMP0034.
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On etudie l'extraction d'un cation metallique pour le couplage d'une reaction d'extraction et d'une reaction d'oxydation. On veut suivre l'influence d'une phase fluide immisable sur l'hydrodynamique et la cinetique reactionnelle d'un melange gaz-liquide
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Anastassiades, Evanguelos. "Étude du fonctionnement de mobiles auto-aspirants dans les réacteurs agités gaz-liquide". Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL126N.
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Le fonctionnement de contacteurs gaz-liquide alimentés en gaz par différentes turbines autoaspirantes associées à un arbre creux a été étudié. Une étude comparative a été menée sur l'hydrodynamique globale et locale du réacteur de 0,6 m de diamètre équipé des turbines suivantes: (1) turbine carénée radiale de D/T = 1/3 ; (2) turbine Rushton modifiée D/T = 0,25 ; D/T = 1/3 ; D/T = 0,4 ; (3) turbine à pales inclinées modifiée D/T = 0,35. Plusieurs techniques de mesure de l'hydrodynamique locale ont été testées dans l'optique d'une modélisation du réacteur en terme de modèle de zones interconnectées. L’étude de la turbine carénée a montré que le réacteur ne peut pas être décrit par un modèle de réacteur parfaitement agité du fait de la mauvaise circulation du liquide liée à la géométrie de la turbine. Ainsi, les caractéristiques du champ de vitesses des deux phases ont été déterminées et ont permis de délimiter les différentes zones du réacteur. L'étude concernant la turbine Rushton autoaspirante a permis de mettre en évidence les différents régimes de fonctionnement liés aux phénomènes de formation de différents types et structures de cavités derrière les pales du mobile ; les transitions de régime étant alors identifiées grâce au nombre de Froude modifié. En ce qui concerne l'hydrodynamique locale de ce mobile, la cartographie des vitesses des deux phases a montré que le caractère parfaitement agité correspondait à un volume du réacteur nettement plus important que dans le cas du mobile précédent. La géométrie de la turbine à pales inclinées défavorise l'entrainement du gaz par autoaspiration mais offre en revanche une bonne circulation du liquide à puissance consommée modérée. Ce mobile peut être de ce fait aussi attractif que les deux turbines précédentes
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Zhao, Donglin. "Liquid macro- and micro-mixing in sparged and boiling stirred tank reactors". Thesis, University of Surrey, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395548.
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Weber, Sebastian [Verfasser], Markus [Gutachter] Pietzsch, Jochen [Gutachter] Büchs i Martin [Gutachter] Sommerfeld. "Jet aerated loop reactors as alternative to stirred tank reactors / Sebastian Weber ; Gutachter: Markus Pietzsch, Jochen Büchs, Martin Sommerfeld". Halle (Saale) : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2019. http://d-nb.info/1210730871/34.
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Hu, Windy Chiung Wen. "Anaerobic digestion of liquid wastewaters from food industry using continuously stirred tank reactors". Thesis, University of Birmingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531076.
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This thesis describes an investigation on the application of anaerobic contact process treating a variety of wastewaters from food industries (raw molasses, purge wastes, ice-cream and diary wastewaters). The raw molasses is one of the wastes produced from the sugar industries, which contains high concentrations of organic matters and high concentrations of sulphate and was firstly investigated in this work. A series of batch experiments were carried out to establish a suitable feedstock for pilot scale digesters. A 1% mass molasses medium with a COD: N: P ratio of 200: 5: 1 in a buffer system has been shown to give a successful digestion of molasses with a methane yield of 0.36 l/g CODrem and a COD removal of 89 % from the batch experiment 3. Two pilot scale digesters (14.13 1) were fed with the molasses medium that was established from the batch experiment 3 as suitable for this work. Several organic loading rates were investigated. After feeding with the molasses medium for about 30 days, both pilot digesters have reached steady-state conditions with respect to a COD removal in excess of 90 % and methane yield in excess of 0.321/g CODrem. The process kinetics of anaerobic contact reactor for treating four different wastewaters was investigated. The Monod equation and the Contois equation were used to develop two basic steady-state models. The kinetic parameters required for the application of the steady-state models were determined by using the results obtained from four individual experiments for treating four different wastewaters. Both models were evaluated with four experimental results obtained in this work and a set of routine analysis data obtained from a full scale anaerobic contact reactor treating the ice-cream wastewater for Birds Eye Walls Ltd., (Gloucester). It is found that the Contois model would be more suitable than the Monod model for express the process kinetics of the anaerobic contact process in full scale due to the reason that the Contois model considers the effect of variable influent substrate concentration into the prediction. In addition, the Contois model was found to be better than the Monod model to express the process kinetic when treating the wastewater containing the organic matters, which has a slow rate of hydrolysis (i. e. lipids/proteins).
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Castellano, Simone. "Multiscale study and modeling of dispersion properties relevant for liquid-liquid extraction : adaptation of breakup and coalescence kernels to industrial processes". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1243.
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Ce projet de thèse porte sur l'étude de l'hydrodynamique des dispersions dans les extracteurs liquide-liquide utilisés dans l'industrie du recyclage nucléaire. Dans la première partie du projet, un modèle de bilan de population homogène (0D-PBM), basé sur l'évaluation des taux moyens en volume de coalescence et de rupture, est proposé. La méthode tient compte des inhomogénéités spatiales dans le mélange, notamment de la fonction de densité de probabilité de la dissipation de l’énergie cinétique turbulente dans l’appareil. Le modèle est capable de reproduire les expériences de dispersion liquide-liquide turbulentes à faible viscosité. Dans la deuxième partie de cette étude, un modèle généralisé pour les noyaux de rupture et coalescence, valable pour l’ensemble du spectre de la turbulence, est proposé et validé. La plupart des noyaux disponibles dans la littérature sont basés sur la fonction de structure de second-ordre de Kolmogorov, qui n'est valable que dans le domaine inertiel. Cependant, dans des nombreuses situations rencontrées au niveau industriel, la plupart des gouttes peuvent avoir une taille dans le domaine dissipatif, où la fonction de structure de second-ordre de Kolmogorov ne s'applique pas. Le modèle généralisé est basé sur la fonction de structure de second ordre de Davidson, valable dans tout le spectre de la turbulence. Dans la dernière partie de l'étude, un modèle permettant de simuler le comportement hydrodynamique d'une colonne pulsée est proposé. Le modèle est basé sur un bilan de population 1D, dont les termes source ont été modélisés à l'aide des noyaux de Coulaloglou et Tavlarides généralisés. Les inhomogénéités turbulentes dans la colonne pulsée ont été prises en compte par la fonction de densité de probabilité du taux de dissipation turbulent. Un bon accord modèle-expérience est obtenu en ce qui concerne le diamètre et la concentration moyenne des gouttes dans un compartimentThis PhD project deals with the study of the hydrodynamics of the dispersions in the liquid-liquid extractors employed in the nuclear recycle industry. In the first part of the project, a zero-dimensional homogenous Population Balance Model (0D-PBM), based on the evaluation of the volume-averaged coalescence and breakup rates, is adopted to fit low-viscosity turbulent liquid-liquid dispersion experiments. The method accounts for the spatial inhomogeneities in mixing, namely for the probability density function of the turbulent kinetic energy dissipation in the apparatus. In the second part of this study, a generalized model for the breakage and coalescence kernels, valid for the entire spectrum of turbulence, is proposed and validated. Most of the available kernels in literature indeed are based on the Kolmogorov second-order structure function, which is only valid in the inertial subrange. However, in many industrially encountered situations, most of the droplets may have size in the dissipation range, where the Kolmogorov second-order structure function does not apply. The generalized model is based on the Davidson second-order structure function, valid in the entire spectrum of turbulence. In the last part of the study, a model that allows to simulate the hydrodynamic behavior of a pulsed column is proposed. The model is based on a 1D Population Balance Equation (1D-PBE), whose source terms were modeled through the generalized Coulaloglou and Tavlarides kernels. The turbulent inhomogeneities in the pulsed column were accounted through the probability density function of the turbulent dissipation rate. The model well reproduces the experimental Sauter mean diameters and the dispersed phase volume fractions in a compartment of the pulsed column
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Medeiros, de Lima Filho Nelson. "Hydrogénolyse catalytique d'amidon de maïs en réacteur gaz-liquide-solide mécaniquement agité". Vandoeuvre-les-Nancy, INPL, 1996. http://www.theses.fr/1996INPL042N.
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L’objectif de notre recherche est d'une part, l'approfondissement des connaissances hydrodynamiques et de transfert gaz-liquide d'un réacteur triphasé mécaniquement agité et d'autre part, la recherche des conditions optimales des réactions d'hydrogénolyse catalytique du glucose et de l'amidon. Les caractéristiques hydrodynamiques et du transfert gaz-liquide sont obtenues à l'aide de méthodes physiques en régime dynamique. Les paramètres étudiés sont: le débit gazeux, la vitesse d'agitation et la pression totale. Les grandeurs déduites sont: l'état du macro-mélange, le taux de rétention de la phase gazeuse et la conductance globale du transfert gaz-liquide. L’hydrogénolyse directe d'une suspension aqueuse d'amidon avec un catalyseur à base ruthénium imprégné sur charbon actif peut être effectuée en présence d'acide acétique. La sélectivité de la transformation en glycérol et diols dépend du cation associe à l'ion acétate. Les meilleurs résultats sont obtenus pour les cations calcium et sodium associé à l'ion acétate. Une addition supplémentaire d'hydroxyde de calcium est également favorable. Toutefois, dans les conditions opératoires étudiées, le catalyseur au ruthénium reste peu sélectif et il conduit en parallèle à la formation d'acides organiques. Enfin, l'hydrogénolyse directe de l'amidon, en présence d'acide acétique, peut être modélisée convenablement à l'aide d'un modèle cinétique phénoménologique ou les quatre étapes réactionnelles sont du 1er ordre
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Tilland, Airy. "Étude de l’évolution de la réactivité des matériaux porteurs d’oxygène dans un procédé de combustion en boucle chimique". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0218/document.
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Le procédé de captage du dioxyde de carbone (CO2) par combustion fonctionnant en boucle chimique (Chemical Looping Combustion (CLC)) permet de produire de l’énergie à partir du méthane tout en captant le CO2 produit par la combustion. Ce procédé met en oeuvre un matériau porteur d’oxygène (NiO/NiAl2O4) qui est utilisé pour fournir de l’oxygène lors de la combustion du méthane et qui est ensuite régénéré sous air. Le matériau utilisé se dégrade au cours du temps ce qui accroît les coûts du procédé et diminue ses performances. L’étude présentée ici a pour objectif de déterminer quel est l’impact des phénomènes thermiques et chimiques sur la dégradation du matériau porteur d’oxygène. Les mécanismes réactionnels représentant la réduction et l’oxydation du porteur d’oxygène ont été déterminés et validés grâce à des études expérimentales et à la modélisation d’un réacteur parfaitement auto-agité (RPAA) et d’un réacteur à écoulement piston. L’importance du contrôle du dépôt de carbone dans le procédé a été démontrée. Ensuite, les paramètres cinétiques des réactions représentant la réduction de l’oxyde de nickel ont pu être déterminés grâce à un modèle original du RPAA, puis validés dans le réacteur piston. L’intérêt du RPAA pour la détermination de paramètres cinétiques dans le cas du procédé CLC a été présenté. Les paramètres obtenus permettent de prédire de manière correcte toutes les réactions même si un travail complémentaire est nécessaire pour obtenir une meilleure précision des résultats. Finalement, un mécanisme de dégradation du matériau porteur d’oxygène déduit des résultats expérimentaux a été proposé. Ce mécanisme décrit la production importante de fines particules se dissociant des grains et leur rôle dans les phénomènes d’agglomération observés. Le matériau support, supposé inerte, jouerait un rôle dans l’apport d’oxygène. La méthodologie développée dans ce travail pourrait être adaptée à l’analyse et la caractérisation d’autres matériaux porteurs d’oxygèneThe Chemical Looping Combustion (CLC) process produces energy by combustion of methane while capturing the carbon dioxide (CO2). An oxygen carrier (NiO/NiAl2O4) is used to deliver oxygen during the combustion of methane. It is then regenerated by air. The oxygen carrier material degrades over time, which increases the costs of the process and reduces its performance. The present study aims at determining the impacts of thermal and chemical phenomena on the oxygen carrier degradations. The reaction mechanisms corresponding to the reduction and oxidation of the oxygen carrier are determined and validated through experimental studies and the modeling of a continuously auto-stirred tank reactor (CASTR) and a plug flow reactor. The importance of controlling the quantity of deposited carbon in the process is illustrated. Then, the kinetic parameters of the reactions representing the reduction of nickel oxide are determined with an original model of the CASTR and validated in the plug flow reactor. The interest of using the CASTR for the determination of kinetic constants of the reactions involved in CLC process is presented. The obtained parameters give a good description of all reactions even if additional work is required to obtain a better precision of the results. Finally, a degradation mechanism of the oxygen carrier has been proposed. This mechanism describes the large production of fine particles separated from the grains and their role in the observed agglomeration phenomena. The support material, supposed to be inert, provides some of its oxygen. The methodology developed in this work could be adapted for the analysis and the characterization of other oxygen-carriers