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Simulation of Hydrocarbon Waste-gas Combustion in Incinerator and Pollution Control
,
M.Sc. Thesis
Sharif University of Technology
;
Darbandi, Masoud
(Supervisor)
Abstract
Emission control, especially Carbon Monoxides (CO) as one of the major by-products of combustion processes, is one of the most serious challenges in burning waste-gases with high amounts of humidity and Carbon Monoxide. We investigated an oil waste-gas incinerator serving to a bitumen production line located in Pasargad Oil Company, Shazand, Arak, Iran. The aforementioned incinerator was criticized seriously for its high CO emissions. We were requested to find a solution to reduce the undesirable CO emission from that. Following the environmental standards, there is an upper limit of 150 ppm for the CO produced by an industrial waste oil incinerator. To present an inclusive solution for such...
Optimal Control of Chemical Reactors Based on Optimization Methods Inspired from Artificial Immune Systems
, M.Sc. Thesis Sharif University of Technology ; Pishvaie, Mahmoud Reza (Supervisor)
Abstract
Artificial immune systems (AIS) constitute a novel area of bio-inspired computing. Biological models of the natural immune system, in particular the theories of clonal selection, immune networks and negative selection, have provided the inspiration for AIS algorithms. Moreover, such algorithms have been successfully employed in a wide variety of different areas, but have not been applied for chemical processes yet. One important part of the immune systems is lymphatic system. Clonal selection is one of the few algorithms that belong to the family of AIS techniques. Clonal selection algorithm is the computational implementation of the clonal selection principle. In this project, we have...
Unsteady Analysis of a Slinger Combustion Chamber by the Chemical Reactor Network Model
, M.Sc. Thesis Sharif University of Technology ; Farshchi, Mohammad (Supervisor)
Abstract
Up to early seventies, Gas turbine combustor design was very time consuming and costly process including trial and errors through test rigs. Over the time analytical-experimental relationships take place as one of the key rules in the design processes. With the increasing power of computer calculations, computational fluid dynamics find its way in the procedure. Obtaining a deeper understanding of flow conditions and geometry inside the chamber, a great reduction in production time and cost of revisions to rigs and samples were achieved. Finding a precise prediction of polluting elements like NOx (less than 10 ppm) after many run hours and enormous computing resources, CFD methods must...
Synchronization of Two Chemical Reactors
, M.Sc. Thesis Sharif University of Technology ; Shahrokhi, Mohammad (Supervisor)
Abstract
Chaotic behavior takes place in different physical systems such as chemical reactors. In this thesis, dynamical behavior of chemical reactors in which polymerization or series reactions take place has been considered. It has been shown that these reactors have chaotic dynamics under special condition. Two reactors of the second type (with series reactions) for cases of known and unknown parameters have been synchronized by a control method and stability of the proposed scheme has been established by the Lyapunov stability theorem. Simulation results show the effectiveness of proposed method. Since concentration measurement is difficult and expensive, an observer has been used for...
Mass transport analysis of non-Newtonian fluids under combined electroosmotically and pressure driven flow in rectangular microreactors
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 508 , 2016 , Pages 345-359 ; 09277757 (ISSN) ; Saidi, M. H ; Sharif University of Technology
Elsevier
Abstract
Hydrodynamically fully developed flow of power-law fluids under combined action of electroosmotic and pressure gradient forces in rectangular microreactors is analyzed considering heterogeneous catalytic reactions. The Poisson-Boltzmann, Cauchy momentum, and concentration equations are considered in two dimensions and after being dimensionless are numerically solved applying a finite difference algorithm. Variation of axial concentration gradient, and axial and horizontal mass diffusions are taken into account as well. To accomplish a more general analysis, the velocity distribution is obtained by solving continuity and Cauchy momentum equations and is not considered as an average axial...
Modeling, simulation and control of a tubular fixed-bed dimethyl ether reactor
, Article Chemical and Biochemical Engineering Quarterly ; Volume 24, Issue 4 , 2010 , Pages 415-423 ; 03529568 (ISSN) ; Shahrokhi, M ; Abedini, H ; Sharif University of Technology
2010
Abstract
This paper considers the modeling and control of a tubular fixed bed reactor with recycle stream for dimethyl ether (DME) production. For simulation purposes, a pseudo homogeneous model has been developed. By reactor simulation under steady state condition, effects of parameters such as feed rate, pressure and shell temperature are investigated. Using the steady state model, an optimizer that maximizes the reactor yield has been developed. For cooling the reactor, a steam drum that uses heat of reactions to produce steam was coupled with the reactor. Through dynamic simulation, system open loop response was obtained and two control loops were considered for controlling the reactor...
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
Simulation and experimental studies of methane oxidative coupling reaction in a bench scale fixed bed reactor
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 35, Issue 15 , Aug , 2013 , Pages 1418-1426 ; 15567036 (ISSN) ; Shahrokhi, M ; Pishvaie, M. R ; Zarrinpashneh, S ; Sharif University of Technology
2013
Abstract
Oxidative coupling of methane in a bench scale fixed bed tubular reactor over Mn-Na2WO4/SiO2 catalyst has been studied. Four kinetic models have been considered for oxidative coupling of methane reactions and compared through experimental data, and the best kinetic model has been selected. For removing the heat of reaction, a molten salt bath system surrounding the reactor tube has been proposed. Effects of different factors, such as CH4/O2 ratio, are investigated through experimental and simulation studies. A good agreement has been observed between simulation and experimental data. The reactor behaviors under isothermal and adiabatic conditions have also been simulated
Optimization of reaction rate parameters in modeling of heavy paraffins dehydrogenation
, Article World Academy of Science, Engineering and Technology ; Volume 79 , 2011 , Pages 389-393 ; 2010376X (ISSN) ; Khorasheh, F ; Nakhjavani, M. H ; Fattahi, M ; Sharif University of Technology
2011
Abstract
In the present study, a procedure was developed to determine the optimum reaction rate constants in generalized Arrhenius form and optimized through the Nelder-Mead method. For this purpose, a comprehensive mathematical model of a fixed bed reactor for dehydrogenation of heavy paraffins over Pt-Sn/Al 2O 3 catalyst was developed. Utilizing appropriate kinetic rate expressions for the main dehydrogenation reaction as well as side reactions and catalyst deactivation, a detailed model for the radial flow reactor was obtained. The reactor model composed of a set of partial differential equations (PDE), ordinary differential equations (ODE) as well as algebraic equations all of which were solved...
Direct conversion of methane to methanol over v 2O 5/Sio 2 catalyst in a fixed-bed reactor utilizing a CFD model
, Article World Academy of Science, Engineering and Technology ; Volume 73 , 2011 , Pages 797-802 ; 2010376X (ISSN) ; Morteza, S ; Fattahi, M ; Sharif University of Technology
Abstract
A dynamic model of oxidation of methane to methanol has been developed in a fixed-bed reactor applying V2O5/SiO2 as the reaction catalyst. The standard k-? model with 10% turbulence amount performed. The effects of temperature (450- 500°C) and pressure (20-120 bar) with residence time of 3 seconds, on methane conversion and methanol or formaldehyde selectivity examined. Oxygen used as an oxidant and the amount of oxygen in feed was 5% mol/mol of methane amount. The results showed with increasing the conversion of methane from 0.66 to 1.52%, the selectivity to methanol decreased from 93.4% to 91.9%. The CFD modeling results showed reasonable agreement with the obtained experimental data of...
Developing a mathematical model for the oxidative dehydrogenation of propane in a fluidized bed reactor
, Article Asia-Pacific Journal of Chemical Engineering ; Volume 11, Issue 3 , 2016 , Pages 448-459 ; 19322135 (ISSN) ; Kazemeini, M ; Fattahi, M ; Sharif University of Technology
John Wiley and Sons Ltd
Abstract
In this research, a mathematical model to simulate a two-phase fluidized bed reactor for oxidative dehydrogenation of propane to propylene was developed. The developed model was solved numerically using the matlab software. Moreover, effects of the reaction temperature, operating pressure, feed composition, particle's size and gas superficial velocity on the reactant conversion, product selectivity and desired product's yield were understudied. The model was validated using previously published experimental data for simulation of the case at the exit of the circulating fluidized bed reactor. The results revealed that, as the temperature raised from 783 to 823 K, the propane conversion...
Selective photooxygenation of dihydroartemisinic acid in a reusable microreactor with physically immobilized photocatalysts
, Article Materials Research Bulletin ; Volume 145 , 2022 ; 00255408 (ISSN) ; Kazemeini, M ; Tyagi, A ; Roxas, A. P ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Photocatalytic production of organic materials including Artemisinin has been hampered in the pharmaceutical industry because of low reusability and selectivity of photocatalysts. In this work, reusable photocatalysts were synthesized through novel physical and electrostatic immobilizations. After four reaction cycles of dihydroartemisinic acid (DHAA) photooxygenation using physically supported photosensitizers, the conversion was slightly reduced from 81 to 78%, indicating their high reusability. This occurred while maintaining the selectivity of the desired product above 85%, which was higher than that of the homogeneous photosensitizers. Then, a continuous-flow microreactor functionalized...
Oxygen permeation and oxidative coupling of methane in membrane reactor: A new facile synthesis method for selective perovskite catalyst
, Article Journal of Molecular Catalysis A: Chemical ; Volume 286, Issue 1-2 , 2008 , Pages 79-86 ; 13811169 (ISSN) ; Nazari, K ; Safekordi, A. A ; Seyed Matin, N ; Ahmadi, R ; Esmaeili, N ; Tofigh, A ; Sharif University of Technology
2008
Abstract
A dense membrane of La0.6Sr0.4Co0.8Fe0.2O3- δ (LSCF) perovskite was prepared by a new chelating agent, ethylene diamine N,N,N′,N′-tetra N-acetyl diamine (EDTNAD). As a potent ligand, EDTNAD provided a facile one-step method to form complexes of the four metal ions, simultaneously. The oxygen permeation flux through the pure perovskite LSCF dense membrane was measured over temperature range of 1073-1223 K, thickness of 0.7-1.0 mm and oxygen partial pressure of 0.1-1.0 bar. Oxidative coupling of methane (OCM) reaction using LSCF disk in the atmospheric membrane reactor and over the temperature range of 1073-1173 K showed a C2 selectivity of 100% and C2 yield of 5.01% at 1153 K. Furthermore,...
The effect of influent COD and upward flow velocity on the behaviour of sulphate-reducing bacteria
, Article Process Biochemistry ; Volume 40, Issue 7 , 2005 , Pages 2305-2310 ; 13595113 (ISSN) ; Ghavipanjeh, F ; Mirjafari, P ; Sharif University of Technology
2005
Abstract
The effect of up velocity and influent COD concentration on the activity of sulphate-reducing bacteria (SRB) in UASB reactors is discussed. To study these effects, four UASB reactors were built and utilized in parallel. Examinations were carried out in two different concentrations of molasses (500 mg COD/l and 1000 mg COD/l) and four different upward flow velocities. It was observed that at velocities greater than 1 m/h, SRB bacteria were easily washed out from the reactors due to lower density and lack of ability to form dense and firm granules. It was found that in low-strength wastewaters with a COD to sulphate ratio of 2, an upward velocity in the range of 1.5-2.5 m/h could be...
Integrated procedure, using differential evolution optimization of rate parameters, for design of small and accurate multistep global chemical mechanisms
, Article Industrial and Engineering Chemistry Research ; Volume 57, Issue 10 , March , 2018 , Pages 3530-3544 ; 08885885 (ISSN) ; Mazaheri, K ; Sharif University of Technology
American Chemical Society
2018
Abstract
Three-dimensional analysis of combustion chambers in industrial gas turbines suffers from lack of simple and accurate reduced mechanisms for oxidation of hydrocarbon fuels. Here, an integrated procedure is introduced based on a differential evolution optimization technique. The procedure is flexible and modular and allows optimization of many rate parameters of a multistep global mechanism based on many different combustion criteria and inlet or operational conditions. The procedure uses any selected chemical reactor model and any reference combustion mechanism provided. Sample design criteria used here are flame temperature, ignition delay time, and concentration of selected species,...
Modeling, simulation and control of a methanol synthesis fixed-bed reactor
, Article Chemical Engineering Science ; Volume 60, Issue 15 , 2005 , Pages 4275-4286 ; 00092509 (ISSN) ; Baghmisheh, G. R ; Sharif University of Technology
2005
Abstract
In this paper, the dynamic behavior and control of the low pressure methanol synthesis fixed bed reactor have been investigated. For simulation purpose, a heterogeneous one-dimensional model has been developed. First, the reactor simulation is carried out under steady-state condition and the effects of several parameters such as shell temperature, feed composition (especially CO2 concentration) and recycle ratio on the methanol productivity and reactor temperature profile are investigated. Using the steady state model and a trained feedforward neural network that calculates the effectiveness factor, an optimizer which maximizes the reactor yield has been developed. Through the dynamic...
Modeling of sorption enhanced steam methane reforming in an adiabatic packed bed reactor using various CO2 sorbents
, Article Journal of Environmental Chemical Engineering ; Volume 9, Issue 5 , 2021 ; 22133437 (ISSN) ; Abbas, S. Z ; Maqbool, F ; Ramirez Solis, S ; Dupont, V ; Mahmud, T ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
A 1-D heterogeneous model of sorption-enhanced steam methane reforming (SE-SMR) process in a packed bed reactor consisting of nickel catalyst well mixed with CO2 sorbent particles is investigated for three types of common sorbents. The performance of SE-SMR process is studied under low medium pressure conditions (3 – 11 bar) to find the optimum operating conditions. Optimal CaO sorption corresponding to 82% CH4 conversion and 85% H2 purity is found at 900 K, 3 bar, 3.5 kgm−2s−1 and S/C of 3.0. In contrast, lithium zirconate (LZC) and hydrotalcite (HTC) sorbents exhibited best sorptions under the operating conditions of 773 K, 5 bar and S/C of 3 with CH4 conversion of 91.3% and 55.2%, and H2...
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...
Adaptive fuzzy approach for H∞ temperature tracking control of continuous stirred tank reactors
, Article Control Engineering Practice ; Volume 16, Issue 9 , September , 2008 , Pages 1101-1108 ; 09670661 (ISSN) ; Shahrokhi, M ; Sharif University of Technology
2008
Abstract
In this paper, an adaptive fuzzy temperature controller is proposed for a class of continuous stirred tank reactors (CSTRs) based on input-output feedback linearization. Since for control implementation concentrations of all species are needed, based on the observability concept, a fuzzy logic system is used to estimate the concentration dependent terms and other unknown system parameters in the control law, using temperature measurements. It has been shown that the H∞ tracking control performance with a prescribed attenuation level is achieved, by using the proposed controller. Finally the effectiveness of the proposed controller has been demonstrated by applying it to a benchmark chemical...
Two observer-based nonlinear control approaches for temperature control of a class of continuous stirred tank reactors
, Article Chemical Engineering Science ; Volume 63, Issue 2 , 2008 , Pages 395-403 ; 00092509 (ISSN) ; Shahrokhi, M ; Sharif University of Technology
2008
Abstract
In this paper, two nonlinear observer based controllers for temperature control of a continuous stirred tank reactor in which a special class of parallel exothermic reactions take place are proposed. A reduced order nonlinear observer is constructed to estimate the concentration in the reactor. The observer is coupled with two nonlinear controllers, designed based on two well-known techniques, namely input-output linearization and backstepping for controlling the reactor temperature. For dampening the effect of observer error dynamics, a compensating term is used in each control law. The asymptotical stability of the closed-loop system is shown by the Lyapunov's stability theorem. The...