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    Bioleaching of low-grade sphalerite using a column reactor

    , Article Hydrometallurgy ; Volume 82, Issue 1-2 , 2006 , Pages 75-82 ; 0304386X (ISSN) Mousavi, S. M ; Jafari, A ; Yaghmaei, S ; Vossoughi, M ; Roostaazad, R ; Sharif University of Technology
    2006
    Abstract
    The effects of several variables on zinc recovery in column bioleaching have been investigated. The ore contained sphalerite and pyrite as the main sulfide minerals and chalcopyrite and galena as minor minerals. Tests were carried out using a bench-scale column leach reactor which was inoculated with mesophilic (Acidithiobacillus ferrooxidans) and thermophilic (Sulfobacillus) iron oxidizing bacteria; initially isolated from the Sarcheshmeh chalcopyrite concentrate (Kerman, Iran) and Kooshk sphalerite concentrate (Yazd, Iran), respectively. In the inoculated column, jarosite and elemental sulfur were formed. The leaching rate of sphalerite tended to increase with dissolved ferric ion... 

    Simulation, Optimization and Control of FT Slurry Bubble Column Reactor

    , M.Sc. Thesis Sharif University of Technology Mohammadnezami, Hossein (Author) ; Bozorgmehry Bouzarjomehr, Ramin (Supervisor)
    Abstract
    Fischer-Tropsch (FT) is a process which is studied recently by many companies and researchers. Due to limited sources of petroleum, conversion of Synthesis gas to liquid hydrocarbons as gasoil, gasoline has been considered a lot from 1980. In this thesis new design for FT process is presented (based on Fe-Cu-K catalyst) to produce gasoline, gasoil and wax, this design is simulated by HYSYS 3.1 software. Lumping strategy of reactions involved in FT mechanism is used to reduce simulation time. Not being FT reactions in HYSYS, reaction extensions are used (via customization capability) to include complex lumped reaction rates. Afterward, PI controller is implemented to control concentration... 

    Modeling of Fischer-Tropsch Synthesis Reactor for GTL Process

    , M.Sc. Thesis Sharif University of Technology Al Taha Motahar, Narges Khatoon (Author) ; Khorasheh, Farhad (Supervisor) ; Taghikhani, Vahid (Supervisor)
    Abstract
    There is a need from the natural gas and energy industries to seek for an economically attractive way of converting remote gas reserves into transportable products, such as high quality fuels or petrochemicals. A possible way for the conversion of natural gas to middle distillates is based on a three-step process. Firstly, production of syngas from natural gas. Secondly,catalytic conversion of syngas into hydrocarbons, mostly parafins from C5 to C100. (Fischer-Tropsch (F-T) synthesis). Thirdly, hydrocracking of the heavy paraffinic hydrocarbons to middle distillates. The F-T synthesis step is highly exothermic. In order to control the temperature within the reactor, when considering high... 

    2D and 3D simulation of bubble columns using CFD methods

    , Article CHISA 2006 - 17th International Congress of Chemical and Process Engineering, Prague, 27 August 2006 through 31 August 2006 ; 2006 ; 8086059456 (ISBN); 9788086059457 (ISBN) Irani, M ; Bozorgmehri, R ; Sharif University of Technology
    2006
    Abstract
    This article presents the results of 2D and 3D simulations of a bubble column reactor at steady state conditions and low gas flow rates. The simulations have been done based on a two-fluid model with a k - ε model used for turbulence modeling. The experimental data have been obtained by differential pressure transducer. For analyzing of hydrodynamic parameters such as hold up and velocity profiles of phases, a system consists of water tank and air aerated from bottom is set up. The simulations have been done based on two different approaches which are mixture and eulerian approaches. Despite the fact that these approaches lead to similar results, the convergence and stability of eulerian... 

    Dme direct synthesis from syngas in a large-scale three-phase slurry bubble column reactor: transient modeling

    , Article Chemical Engineering Communications ; Vol. 201, issue. 5 , Nov , 2014 , pp. 612-634 ; ISSN: 00986445 Papari, S ; Kazemeini, M ; Fattahi, M ; Fatahi, M ; Sharif University of Technology
    Abstract
    In this research, a new transient mathematical model based upon tanks-in-series configuration was developed to simulate the direct synthesis of dimethyl ether (DME) from syngas in a commercial-scale slurry bubble column reactor. A comparison between the simulation results and experimental data showed that the applied model might acceptably describe the behavior of the slurry reactor. Furthermore, simulation results in the heterogeneous bubble flow regime indicated that the proposed model with 10 tanks-in-series provided the optimum condition. Utilizing this transient model and considering catalyst deactivation, the effect of operating conditions on DME productivity and CO conversion were... 

    Mathematical modeling of a slurry bubble column reactor for hydrodesulfurization of diesel fuel: Single- and two-bubble configurations

    , Article Chemical Engineering Research and Design ; Volume 100 , August , 2015 , Pages 362-376 ; 02638762 (ISSN) Khadem Hamedani, B ; Yaghmaei, S ; Fattahi, M ; Mashayekhan, S ; Hosseini Ardali, S. M ; Sharif University of Technology
    Institution of Chemical Engineers  2015
    Abstract
    In this investigation, a mathematical model for HDS of diesel fuel in a slurry bubble column reactor was developed. The model is based on the axial dispersion of the heterogeneous gas flow regime, which includes two various bubble classes: large (20±70mm) and small (1±10mm). By assuming only large or large plus small bubbles in the column, single- and two-bubble class mode equations are developed. The developed models to solving the mass and enthalpy balances from which the sulfur conversion was obtained that undertaken. The chemical kinetics over NiMoS/γ-Al2O3 catalyst were undertaken for the reaction rate of the involved reactions. The reactor operating conditions... 

    CFD Simulation of hydrodynamic of a bubble column reactor operating in churn-turbulent regime and effect of gas inlet distribution on system characteristics

    , Article International Journal of Chemical Reactor Engineering ; Volume 14, Issue 1 , 2016 , Pages 213-224 ; 15426580 (ISSN) Azimi Yancheshme, A ; Zarkesh, J ; Rashtchian, D ; Anvari, A ; Sharif University of Technology
    Walter de Gruyter GmbH 
    Abstract
    CFD simulation of cylindrical bubble column including air as dispersed phase and water as continuous phase operating in churn-turbulent flow regime with diameter of 0.49 m, height of 3.6 m and gas superficial velocity of 0.14 m/s have been conducted. All simulations have been carried out in a 2D axisymmetric, unsteady and Euler/Euler framework with the aid of commercial software FLUENT v. 14.5. Simulations were validated by our experimental results through residence time distribution (RTD) data. Effect of bubble size distribution at inlet on column hydrodynamic was investigated and results clearly showed that equilibrium bubble size distribution in most parts of column is independent of... 

    Modeling of catalyst deactivation in catalytic wet air oxidation of phenol in fixed bed three-phase reactor

    , Article World Academy of Science, Engineering and Technology ; Volume 73 , 2011 , Pages 604-609 ; 2010376X (ISSN) Golestani, A ; Kazemeini, M ; Khorasheh, F ; Fattahi, M ; Sharif University of Technology
    Abstract
    Modeling and simulation of fixed bed three-phase catalytic reactors are considered for wet air catalytic oxidation of phenol to perform a comparative numerical analysis between tricklebed and packed-bubble column reactors. The modeling involves material balances both for the catalyst particle as well as for different fluid phases. Catalyst deactivation is also considered in a transient reactor model to investigate the effects of various parameters including reactor temperature on catalyst deactivation. The simulation results indicated that packed-bubble columns were slightly superior in performance than trickle beds. It was also found that reaction temperature was the most effective... 

    The effects of Fe(II) and Fe(III) concentration and initial pH on microbial leaching of low-grade sphalerite ore in a column reactor

    , Article Bioresource Technology ; Volume 99, Issue 8 , 2008 , Pages 2840-2845 ; 09608524 (ISSN) Mousavi, S. M ; Yaghmaei, S ; Vossoughi, M ; Roostaazad, R ; Jafari, A ; Ebrahimi, M ; Chabok, O. H ; Turunen, I ; Sharif University of Technology
    2008
    Abstract
    In this study the effects of initial concentration of Fe(II) and Fe(III) ions as well as initial pH on the bioleaching of a low-grade sphalerite ore in a leaching column over a period of 120 days with and without bacteria were investigated. Four different modifications of medium were used as column feed solutions to investigate the effects of initial concentration of Fe(II) and Fe(III) ions on zinc extraction. The experiments were carried out using a bench-scale, column leaching reactor, which was inoculated with mesophilic iron oxidizing bacteria, Acidithiobacillus ferrooxidans, initially isolated from the Sarcheshmeh chalcopyrite concentrate (Kerman, Iran). The effluent solutions were... 

    Fast dynamic interfacial tension measurements and dilational rheology of interfacial layers by using the capillary pressure technique

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 407 , August , 2012 , Pages 159-168 ; 09277757 (ISSN) Javadi, A ; Krägel, J ; Makievski, A. V ; Kovalchuk, V. I ; Kovalchuk, N. M ; Mucic, N ; Loglio, G ; Pandolfini, P ; Karbaschi, M ; Miller, R ; Sharif University of Technology
    Elsevier  2012
    Abstract
    The oscillating drop and bubble analyzer (ODBA) is an experimental set-up based on the measurement of capillary pressure under static and dynamic conditions. It allows studies of slow and fast dynamic surface and interfacial tensions, following different growing and oscillating drop or bubble protocols, as well as determination of the dilational interfacial visco-elasticity of liquid interfacial layers. For the visco-elasticity studies, drops or bubbles are subjected to harmonic oscillations of area or volume in a broad frequency range, and the resulting harmonic capillary pressure response is analyzed by Fourier analysis. Also, transient relaxations can be easily performed, which are of... 

    Mathematical modeling of a slurry reactor for DME direct synthesis from syngas

    , Article Journal of Natural Gas Chemistry ; Volume 21, Issue 2 , March , 2012 , Pages 148-157 ; 10039953 (ISSN) Papari, S ; Kazemeini, M ; Fattahi, M ; Sharif University of Technology
    2012
    Abstract
    In this paper, an axial dispersion mathematical model is developed to simulate a three-phase slurry bubble column reactor for direct synthesis of dimethyl ether (DME) from syngas. This large-scale reactor is modeled using mass and energy balances, catalyst sedimentation and single-bubble as well as two-bubbles class flow hydrodynamics. A comparison between the two hydrodynamic models through pilot plant experimental data from the literature shows that heterogeneous two-bubbles flow model is in better agreement with the experimental data than homogeneous single-bubble gas flow model. Also, by investigating the heterogeneous gas flow and axial dispersion model for small bubbles as well as the...