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Transesterification of waste cooking oil to biodiesel using KOH/γ-Al2O3 catalyst in a new two-impinging-jets reactor
, Article Industrial and Engineering Chemistry Research ; Vol. 53, Issue. 31 , 2014 , Pages 12238-12248 ; ISSN: 08885885 ; Molaei Dehkordi, A ; Sharif University of Technology
Abstract
In this article, the transesterification of waste cooking oil (WCO) to biodiesel fuel (BDF) has been studied using KOH loaded on millimetric γ-Al2O3 particles in a novel type of two-impinging-jets reactor (TIJR). The effects of various parameters such as KOH loading (wt %), catalyst loading, and methanol-to-oil molar ratio on the BDF yield were studied. The catalyst particles with a KOH loading of 25 wt % at appropriate reaction conditions (i.e., catalyst loading = 4 wt % and methanol-to-oil molar ratio = 15:1) and at 65 °C were used in the TIJR. The influences of various operating and design parameters such as jet Reynolds number value, feed flow rate, jet diameter, and the internozzle...
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) ; 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...
Catalytic wet peroxide oxidation of phenol in a new two-impinging-jets reactor
, Article Industrial and Engineering Chemistry Research ; Volume 48, Issue 23 , 2009 , Pages 10619-10626 ; 08885885 (ISSN) ; Ebrahimi, A. A ; Sharif University of Technology
Abstract
The catalytic wet peroxide oxidation (CWPO) of phenol with activated carbon (AC) as the catalyst has been successfully tested in a novel type of two-impinging-jets reactor (TIJR). The TIJR is characterized by a high-intensity reaction chamber, which is separated by a perforated plate from other parts of the reactor. The perforated plate was used as a filter to keep the catalyst particles within the reaction chamber. The influences of various operating and design parameters such as jet Reynolds number, feed flow rate, internozzle distance, and the jet diameter on the performance capability of the TIJR were investigated. As a result of the impinging process, turbulence, complex trajectory of...
Comparison of conventional and spherical reactor for the industrial auto-thermal reforming of methane to maximize synthesis gas and minimize CO2
, Article International Journal of Hydrogen Energy ; Volume 42, Issue 31 , 2017 , Pages 19798-19809 ; 03603199 (ISSN) ; Saeidi, S ; Najari, S ; Gallucci, F ; Sharif University of Technology
Abstract
Auto-thermal reforming (ATR), a combination of exothermic partial oxidation and endothermic steam reforming of methane, is an important process to produce syngas for petrochemical industries. In a commercial ATR unit, tubular fixed bed reactors are typically used. Pressure drop across the tube, high manufacturing costs, and low production capacity are some disadvantages of these reactors. The main propose of this study is to offer an optimized radial flow, spherical packed bed reactor as a promising alternative for overcoming the drawbacks of conventional tubular reactors. In the current research, a one dimensional pseudo-homogeneous model based on mass, energy, and momentum balances is...
Modeling and Characterizing Transient Behavior of Distillation Columns with Travelling Wave Theory
, M.Sc. Thesis Sharif University of Technology ; Pishvaie, Mahmoud Reza (Supervisor)
Abstract
Simulation and controlling nonlinear process is one of the challenging problems in academic and industrial research. Saving data for keeping history of process or arising number of calculation for optimization in control design, is forcing to decrease number of equation or order of system. One of the methods to decrease the order of distillation process is using the travelling wave theory. This solution shows god accuracy for simulation the behavior of distillation column. On the other hand finite difference method as a solver for distillation equation takes some time to converge to steady state condition and the numbers of calculation in this method are high. Finite difference method is...
Dehydration of THF Using Different Zeolites
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
The aim of this work was to investigate the performance of different kinds of Linde type A zeolite (LTA) for the dehydration of Tetrahydrofuran (THF)-water solution. Batch experiments were carried out to evaluate the effect of various operating parameters such as contact time, initial concentration, mixing temperature (10, 15,and 25 C), amount of adsorbent, and zeolite type(3A, 4A, and 5A zeolites). In theoretical studies, we took the advantage of several types of equilibrium model isotherms such as Langmuir, Freundlich, Dubin-Kaganer-Radushkevich (DKR) to describe the experimental adsorption data. Besides, three adsorption kinetic models including pseudo-first-order, pseudo-second-order,...
Experimental Studies on Biodiesel Production Using Waste Frying Oil in a Hetergogeneous Catalytic Reaction
, M.Sc. Thesis Sharif University of Technology ; Kariminia, Hamid Reza (Supervisor) ; Shaygan Salek, Jalaloddin (Supervisor) ; Pazouki, Mohammad (Co-Advisor)
Abstract
Biodiesel can be a good alternative for fossil diesel since it isrenewable, biodegradable and non-toxic. Also, in comparison with fossil fuels, it emits less air pollutants and greenhouse gases.Findacost effective and environmentally friendly wayforcontinuousproductionofbiodieselcanaddressmany of our environmental concerns. In this study, we applied heterogeneous alkali-catalyzed transesterification as method and used waste frying oil as a low cost feedstock for biodiesel production. The project was performed in two phases. First, experiments were conducted in astirred reactor to finda suitable catalyst which was strontium carbonate calcinated for 3:24 hours in 975̊C.
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Adsorption Process Modeling by Rigorous Solution Method, on the Packed Bed Filled Zeolite
, M.Sc. Thesis Sharif University of Technology ; Rashtchian, Davood (Supervisor) ; Taghikhani, Vahid (Supervisor) ; Farhadi, Fatolla (Supervisor)
Abstract
The appearance of water in pipe lines of the natural gas transportation would cause several problems. In this regard, disparate methods have been developed to produce and refine of the natural gas, and one of the most common method is adsorption process. In this study, modeling and simulation of the adsorption process in the packed bed of zeolite 4A has been done. This research includes four steps, first, adsorption process and all types of adsorbent were investigated. Second, using rigorous solution method, equations of mass and energy balance derived. Third, using the collocation method and MATLAB programing, system equations of mass and energy was solved. Finally, accuracy of simulation...
Carbon Dioxide Absorption with Chemical Reaction in the Presence of Magnetic Nanoparticles and Magnetic Field
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
It has been shown that absorption of carbon dioxide can be enhanced using nanoparticles and in the presence of magnetic field. In the present work, the influences of ferrofluids and magnetic fields on the absorption of CO2 in packed-bed contactors have been investigated carefully. In this regard, multi-tube approach has been applied to model the contactor. The simulation results were validated against experimental data reported in the literature in the absence of nanoparticles and magnetic fields and good agreement was obtained. The influences of variable operating conditions on the contactor performance were carefully investigated. It was found that for 3.4% volume percent of magnetic...
Application of Sulfur Degrading Bacteria in Bioremediation
, M.Sc. Thesis Sharif University of Technology ; Kariminia, Hamid Reza (Supervisor)
Abstract
The main objective of this research was to evaluate the application of a new strain of Brevundimonas naejangsanensis which is newly identified sulfate-reducing bacteria (SRB), in bioremediation. A laboratory scale packed bed reactor (PBR) was fabricated and operated to study the new bacteria’s feasibility on SO_4^(2-) reduction. The reactor was packed with polyurethane foam cubes and operated under different feeding and operating conditions of HRT, COD/SO_4^(2-) ratio and salinity. A maximum SO_4^(2-) reduction of 73.6% was achieved in the PBR when operated at an HRT of 12 h with SO_4^(2-) concentration of 670 mg/L, COD/SO_4^(2-) ratio of 1 and salinity of 3%. The results show that this...
Investigation of Sulfate Reducing Bacteria for Treatment of Wastewaters Polluted by Heavy Metals
, M.Sc. Thesis Sharif University of Technology ; Kariminia Hamedani, Hamid Reza (Supervisor) ; Borghei, Mehdi (Supervisor)
Abstract
The main objective of this research was to evaluate the application of a new strain of Brevundimonas naejangsanensis which is newly identified sulfate-reducing bacteria (SRB), in chromium(VI) removal in contaminated wastewater. A laboratory scale packed bed reactor (PBR) was fabricated and operated to study the bacteria’s feasibility on chromium(VI) reduction and removal. The reactor was packed with polyurethane foam cubes and operated under different feeding and operating conditions of HRT, COD/〖SO〗_4^(2-) ratio and influent chromium(VI) concentration. A maximum chromium removal of 94.6% was achieved in the PBR when operated at an HRT of 24 h with COD/〖SO〗_4^(2-) ratio of .70 and influent...
Investigation of Operating Parameters for Thorium Adsorption from Wastewater by Using of Radiated Grafting Polymeric Adsorbents in Packed Bed Column
, M.Sc. Thesis Sharif University of Technology ; Outokesh, Mohamad (Supervisor) ; Torab Mostaedi, Meysam (Supervisor) ; Asadollahzadeh, Mehdi (Co-Supervisor) ; Torkaman, Rezvan (Co-Supervisor)
Abstract
Today, the pollution of heavy metals in wastewater and surface waters, which is a global environmental problem, has increased with the expansion of various industrial activities. Heavy metals cause serious health problems due to their accumulation in human and animal tissues. Thorium, is a radioactive element with an atomic number of 90 that is widely used in the optics, aerospace, metallurgy and chemical industries, in the manufacture of high-strength alloys, in UV photocells, and especially in the nuclear industry. The primary sources of radioactive wastewater include nuclear power plants, nuclear energy industry research centers, medical institutions, industrial production, universities,...
A non-isothermal, transient model of a non-catalytic reaction in a packed bed with a multi-component high-temperature gas mixture
, Article 3rd M.I.T. Conference on Computational Fluid and Solid Mechanics, Boston, MA, 14 June 2005 through 17 June 2005 ; 2005 , Pages 1023-1025 ; 0080444814 (ISBN); 9780080444819 (ISBN) ; Saboohi, Y ; Sharif University of Technology
2005
Abstract
A mathematical model has been developed to simulate heterogeneous reactions with a complex set of physicochemical and thermal phenomena in a packed bed. These include the chemical reaction itself, the transport of gaseous species in the pores, the generation or consumption of heat by the reactions, and the transport of heat in the porous domain. Solution of complicated sets of governing equations is based upon the concept of a finite volume fully implicit approach. The model has then been applied to analyze the reduction of a hematite pellet in a moving packed bed reactor. © 2005 Elsevier Ltd
Bed moisture estimation by monitoring of air stream temperature rise in packed-bed solid-state fermentation
, Article Chemical Engineering Science ; Volume 61, Issue 17 , 2006 , Pages 5654-5663 ; 00092509 (ISSN) ; Roostaazad, R ; Mitchell, D. A ; Miranzadeh, M ; Bozorgmehri, R ; Safekordi, A ; Sharif University of Technology
2006
Abstract
We develop a method for predicting the moisture content of the fermenting solids in an intermittently mixed packed-bed bioreactor on the basis of measurements of the inlet and outlet gas stream temperatures and the assumption that both the gas streams are saturated with water vapor. This method can be used to estimate when an intermittently mixed packed bed should be mixed and how much water should be added during the mixing event. The predictions were experimentally verified for the growth of Aspergillus niger on wheat bran in a thin packed bed. We show that the application of a controller based on our estimation method would have led to adequate moisture control, with significant errors in...
Investigation of flow dynamics in porous media using computer simulation
, Article 20th European Simulation and Modelling Conference, ESM 2006, Toulouse, 23 October 2006 through 25 October 2006 ; 2006 , Pages 157-163 ; Zamankhan, P ; Mousavi, S. M ; Pietarinen, K ; Sarkomaa, P ; Sharif University of Technology
EUROSIS
2006
Abstract
The aim of this work is to investigate flow hydrodynamics in porous media. Random non-overlapping spherical particles in a cylindrical geometry were produced as a porous media. Navier-Stokes equations in three-dimensional porous packed bed have been solved and dimensionless pressure drop has been studied for a fluid flow through the porous media at different Reynolds numbers (based on pore permeability and interstitial fluid velocity). The numerical results are in good agreement with those reported by Macdonald (1979) in the range of Reynolds numbers studied. At higher Reynolds numbers turbulent models such as large eddy simulation (LES) and Reynolds stress model (RSM) also have been...
Simulation of fluid flow through a granular bed
, Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) ; Mousavi, S. M ; Sharif University of Technology
American Society of Mechanical Engineers
2006
Abstract
Numerical study of flow through random packing of non-overlapping spheres in a cylindrical geometry is investigated. Dimensionless pressure drop has been studied for a fluid through the porous media at moderate Reynolds numbers (based on pore permeability and interstitial fluid velocity), and numerical solution of Navier-Stokes equations in three dimensional porous packed bed illustrated in excellent agreement with those reported by Macdonald [1979] in the range of Reynolds number studied. The results compare to the previous work (Soleymani et al., 2002) show more accurate conclusion because the problem of channeling in a duct geometry. By injection of solute into the system, the...
Numerical investigations of fluid flow and lateral fluid dispersion in bounded granular beds in a cylindrical coordinates system
, Article Chemical Engineering and Technology ; Volume 30, Issue 10 , 2007 , Pages 1369-1375 ; 09307516 (ISSN) ; Turunen, I ; Yousefi, H ; Bastani, D ; Sharif University of Technology
2007
Abstract
Results are presented from a numerical study examining the flow of a viscous, incompressible fluid through a random packing of non-overlapping spheres at moderate Reynolds numbers, spanning a wide range of flow conditions for porous media. By using a laminar model including inertial terms and assuming rough walls, numerical solutions of the Navier-Stokes equations in three-dimensional porous packed beds resulted in dimensionless pressure drops in excellent agreement with those reported in a previous study. This observation suggests that no transition to turbulence could occur in the range of the Reynolds number studied. For flows in the Forchheimer regime, numerical results are presented of...
Optimization of ferrous biooxidation rate in a packed bed bioreactor using Taguchi approach
, Article Chemical Engineering and Processing: Process Intensification ; Volume 46, Issue 10 , 2007 , Pages 935-940 ; 02552701 (ISSN) ; Yaghmaei, S ; Jafari, A ; Vossoughi, M ; Ghobadi, Z ; Sharif University of Technology
2007
Abstract
The biological oxidation of ferrous ion by iron-oxidizing bacteria is potentially a useful industrial process for removal of H2S from industrial gases, desulphurization of coal, removal of sulfur dioxide from flue gas, treatment of acid mine drainage and regeneration of an oxidant agent in hydrometallurgical leaching operations. The main purpose of this study was to find optimum values of the process parameters on the ferrous biooxidation rate by immobilization of a native Sulfobacillus species on the surface of low density polyethylene (LDPE) particles in a packed-bed bioreactor using Taguchi method. Five control factors, including temperature, initial pH of feed solution, dilution rate,...
Modeling of multiple noncatalytic gas-solid reactions in a moving bed of porous pellets based on finite volume method
, Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; Volume 43, Issue 9 , 2007 , Pages 881-894 ; 09477411 (ISSN) ; Saboohi, Y ; Sharif University of Technology
2007
Abstract
A mathematical model is presented to simulate the multiple heterogeneous reactions with complex set of physicochemical and thermal phenomena in a moving bed of porous pellets. This model is based on both heat and mass transfer phenomena of gaseous species in a porous medium including chemical reactions at interfaces whose areas vary during the conversion. This model accounts for both the exothermic and endothermic reactions which can be equimolar or nonequimolar. Furthermore it considers simultaneously the reactions in the nonisothermal transient condition. A powerful technique based upon finite volume fully implicit approach has been implemented to solve the complicated governing equations...
Influence of process variables on biooxidation of ferrous sulfate by an indigenous Acidithiobacillus ferrooxidans. Part II: Bioreactor experiments
, Article Fuel ; Volume 86, Issue 7-8 , 2007 , Pages 993-999 ; 00162361 (ISSN) ; Yaghmaei, S ; Jafari, A ; Sharif University of Technology
2007
Abstract
The oxidation of ferrous iron in solution using Acidithiobacillus ferrooxidans has industrial applications in the regeneration of ferric iron as an oxidant agent for the removal of hydrogen sulfide from waste gases, desulphurization of coal, leaching of non-ferrous metallic sulfides and treatment of acid mine drainage. The aim of this attempt was to increase the biooxidation rate of ferrous sulfate by using immobilized cells. Rate of ferrous iron oxidation was determined in a packed-bed reactor configuration with low density polyethylene (LDPE) particles as support material in order to find the most practical system for scale-up. The present work studies the influence of basic parameters on...