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chemical-reactors
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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...
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...
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...
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...
Renewable hydrogen production by aqueous-phase reforming of Glycerol using Ni/Al2O3-MgO nano-catalyst: effect of the Ni loading
, Article Biomass Conversion and Biorefinery ; 2020 ; Kazemeini, M ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2020
Abstract
Aqueous-phase reforming (APR) of oxygenated hydrocarbons for hydrogen production presents several advantages as feed molecules might be easily found in a wide range of biomass; there is no need for its vaporization and the process allows thorough exploitation of the environmental benefits of using hydrogen as an energy carrier. In this contribution, catalysts with active phase Ni supported on Al2O3-MgO were synthesized at different loadings (1, 3, 5, 7, and 10 wt%) through the co-precipitation technique and tested for the Glycerol APR reaction. Effects of the Ni loading on physicochemical characteristics of Ni/Al2O3-MgO catalysts were examined. Moreover, catalytic performance was...
Oxidation of H2S to elemental sulfur over alumina-based nanocatalysts: Synthesis and physiochemical evaluations
, Article Scientia Iranica ; Volume 23, Issue 3 , 2016 , Pages 1160-1174 ; 10263098 (ISSN) ; Kazemeini, M ; Fattahi, M ; Rashidi, A. M ; Vafajoo, L ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
In this paper, oxidation of H2S into elemental sulfur over synthesized aluminabased nanocatalysts was physiochemically investigated and the results were compared with a commercial Claus catalyst. The wet chemical, co-precipitation, and spray pyrolysis techniques were employed to synthesize several alumina nanostructures. Then, the SEM, XRD, and ASAP analysis methods were utilized to characterize in order to choose the best nanocatalyst. The sulfur and H2S contents were determined through the standard UOP techniques. Amongst the synthesized materials, Al2o3-supported sodium oxide prepared through the wet chemical, and Al2o3 nanocatalysts via spray pyrolysis methods were the most active...
Development of a continuous kinetic model for catalytic hydrodenitrogenation of bitumen
, Article Scientia Iranica ; Volume 14, Issue 2 , 2007 , Pages 152-160 ; 10263098 (ISSN) ; Khorasheh, F ; Gray, M. R ; Sharif University of Technology
Sharif University of Technology
2007
Abstract
Catalytic hydrocracking of topped Athabasca bitumen was investigated in a continuous stirred-basket 0reactor, using a fresh and spent commercial catalyst, as well as in the presence of no catalyst. A continuous lumping model was developed for kinetic analysis of hydrodenitrogenation and hydrocracking reactions. The normalized boiling point was used to describe the reactant mixture as a continuous mixture. The continuous model, with five adjustable parameters, was used to describe hydrocracking reactions. Reactions of nitrogen compounds were described by series reactions, involving cracking to lower molecular weight products, as well as direct denitrogenation. The model was able to accurately...
Morphological investigations of nanostructured V2O5 over graphene used for the ODHP reaction: From synthesis to physiochemical evaluations
, Article Catalysis Science and Technology ; Volume 5, Issue 2 , Sep , 2015 , Pages 910-924 ; 20444753 (ISSN) ; Kazemeini, M ; Khorasheh, F ; Rashidi, A. M ; Sharif University of Technology
Royal Society of Chemistry
2015
Abstract
Oxidative dehydrogenation of propane (ODHP) in a fixed-bed reactor over synthesized vanadia nanocatalysts was investigated physicochemically. Several vanadium pentoxide (V2O5) nanostructures including rod-, belt-, tube-, needle- and flower-like forms were successfully synthesized via reflux and hydrothermal processes utilizing different templates such as monoamines, diamines, aromatic and alcoholic amines. The morphologies of the obtained products were found to be sensitive to the types of templates used. Nanorods obtained were 1.4 μm in length and about 97 nm in width while the VO2(B) nanotubes were of about 76 nm average diameter and up to 1.2 μm long. The diameters of the V2O5 nanotubes...
Simulation of continuous catalytic conversion of glycerol into lactic acid in a microreactor system: A CFD study
, Article Journal of Industrial and Engineering Chemistry ; Volume 104 , 2021 , Pages 258-271 ; 1226086X (ISSN) ; Kazemeini, M ; Sadjadi, S ; Sharif University of Technology
Korean Society of Industrial Engineering Chemistry
2021
Abstract
Hand in hand with the flourish of the biodiesel industry, glycerol (GLY) as an inconvenient by-product has generated environmental and sustainability concerns. Devising measures for efficient transformation of GLY into value-added products is a promising solution. In this contribution, the transformation of GLY to lactic acid (LA) as a valuable chemical was investigated in a continuous process for industrial applications. In this regard, a catalytic method using heterogeneous Cu nanoparticles in NaOH solution was studied in a microreactor by a CFD simulation. A seven-inlet micromixer comprising an optimized mixing unit was incorporated for uniform distribution of the species. The effects 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...
A nonlinear estimation and control algorithm based on ant colony optimization
, Article 2016 IEEE Congress on Evolutionary Computation, CEC 2016, 24 July 2016 through 29 July 2016 ; 2016 , Pages 5120-5127 ; 9781509006229 (ISBN) ; Nasrollahi, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
A new heuristic controller, called Continuous Ant Colony Controller, is proposed for nonlinear stochastic systems. The new controller formulates the states estimation and model predictive control problems as a single stochastic dynamic optimization problem and utilizes a colony of virtual ants to find and track the best state estimation and the best control signal. For this purpose an augmented state space is defined. An integrated cost function is also defined to evaluate the ants within the state space. This function minimizes simultaneously the state estimation error, tracking error, control effort and control smoothness. Ants search the augmented state space dynamically in a similar...
Effects of initial static bed height on fractional conversion and bed pressure drop in tapered-in and tapered-out fluidized bed reactors
, Article International Journal of Multiphase Flow ; Volume 79 , 2016 , Pages 50-61 ; 03019322 (ISSN) ; Molaei Dehkordi, A ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
In this article, a standard 2D Two-Fluid Model (TFM) closed by the kinetic theory of granular flow (KTGF) has been applied to simulate the behavior of tapered-in and tapered-out fluidized bed reactors. In this regard, two types of chemical reactions with gas volume reduction and increase were considered to investigate the effects of initial static bed height on the fractional conversion and bed pressure drop. To validate the CFD model predictions, the results of hydrodynamic simulations concerning bed pressure drop and bed expansion ratio were compared against experimental data reported in the literature and excellent agreement was observed. The obtained simulation results clearly indicate...
Improved H2 production from the APR of polyols in a microreactor utilizing Pt supported on a CeO2–Al2O3 structured catalyst
, Article International Journal of Hydrogen Energy ; Volume 43, Issue 48 , 2018 , Pages 21777-21790 ; 03603199 (ISSN) ; Kazemeini, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In this research, the activity and selectivity of a platinum-based catalyst for H2 production through aqueous phase reforming (APR) in a fixed-bed reactor (FBR) as well as, a structured catalyst microreactor (MR) were investigated. In this venue, first, an in-house designed MR was fabricated and the catalytic material was deposited on the channel walls of this steel made reactor. After verification of the stability of the coated layer, the prepared reactor was employed to investigate the APR reaction. In this regard, APR of the ethylene glycol and glycerol over Pt/Al2O3 and Pt/CeO2–Al2O3 catalyst were conducted in an MR and FBR. Obtained results demonstrated that employing Pt/CeO2–Al2O3 as a...
Synthesis of SiOC/Al2O3 nano/macro composites through PDC method; investigation of potentials as layers of a packed bed reactor membrane
, Article Ceramics International ; Volume 46, Issue 11 , 2020 , Pages 19000-19007 ; Paryab, A ; Rahmani, S ; Akbari, M ; Sarpoolaky, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Thanks to a wide range of pore sizes by nano/macro composites of SiOC/Al2O3, such composites can serve as different layers of the structure of Packed Bed Reactor Membranes (PBRM). In the present study, the Polymer-Derived Ceramics method (PDC) has been used to synthesize nano/macro structures. Firstly, the effect of toluene as an extra carbon source on structure and microstructure of SiOC glass-ceramics was evaluated, such that, 4% (Vol) toluene was recognized as the proper amount to facilitate the synthesis of β-SiC at 1300 °C proved by XRD, Raman spectroscopy, and HR-TEM. Moreover, the presence of micro/meso-porosities was assessed by BET and TEM, indicating the capability of SiOC to serve...
Integrated and inherently safe design and operation of a mobile power generation: Process intensification through microreactor reformer and HT-PEMFC
, Article International Journal of Hydrogen Energy ; Volume 46, Issue 46 , 2021 , Pages 23839-23854 ; 03603199 (ISSN) ; Sharifzadeh, M ; Rashtchian, D ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In the present study, due to various advantages of process miniaturization, the integrated design and operation of a mobile power generation system consisting of a microreactor reformer and a proton exchange membrane fuel cell (PEMFC) are investigated. The hydrogen fuel is supplied through autothermal steam-reforming of methanol in a microreactor leading to a safer, as well as more efficient, and economical operation. A high-temperature polymer membrane fuel cell with external accessories is applied for power generation. Then, simulation-optimization programming is applied for simultaneously optimizing the process design and operation at the same level. The result shows that the implemented...
Design, manufacture and application of a microreactor for the decomposition of ethyl mercaptan on an H-ZSM-5 catalyst
, Article Journal of Cleaner Production ; Volume 292 , 2021 ; 09596526 (ISSN) ; Kazemeini, M ; Mohammadi, A ; Rashidi, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Catalytic decomposition of the ethyl mercaptan over an H-ZSM-5 zeolite in a newly designed microreactor was undertaken in this study. A numerically developed distributor possessing superior flow distribution was amended to 24 parallel microchannels with 64 mm length, 700 μm width, and 600 μm depth. Ethyl mercaptan complete conversion required 350 °C through the developed microreactor while in a conventional fixed-bed-reactor 400 °C was needed. Higher selectivity towards the main products of this decomposition (hydrogen sulfide and ethylene) were observed in this microreactor in comparison to that of a fixed-bed-reactor. In addition, lower selectivity towards formation of byproducts was...
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...
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...
Examining the effect of simulation parameters on coal gasification in tapered fluidized bed reactor
, Article Powder Technology ; Volume 388 , August , 2021 , Pages 505-516 ; 00325910 (ISSN) ; Askaripour, H ; Sharif University of Technology
Elsevier B. V
2021
Abstract
The aim of this study is to assess the influence of oxygen-to-steam ratio, wall boundary conditions, coal feeding rate, and static bed height on the concentrations, heating values, and efficiencies of the product gas in a tapered fluidized bed reactor. Results show that lower and higher heating values slightly vary with increasing the oxygen-to-steam ratio in the range of 0.25–0.35. It is found that cold gas efficiency and carbon conversion efficiency goes up with increased ratio of oxygen to steam; however, both efficiencies decline as a result of increasing the coal feeding rate. As static bed height rises, lower and higher heating values diminish for tapered angle of 5°. For tapered angle...
Two-dimensional CFD simulation of chemical reactions in tapered-in and tapered-out fluidized bed reactors
, Article Advanced Powder Technology ; 2018 ; 09218831 (ISSN) ; Dehkordi, A. M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
This article presents a simulation study of tapered-in and tapered-out fluidized bed reactors to investigate the influences of apex angle on the fractional conversion and the pressure drop of the fluidized beds in the presence of two types of chemical reaction with gas volume increase and reduction. The 2D behavior of tapered-in and -out fluidized beds was also compared with a columnar one from fractional conversion and bed pressure drop point of views. To validate the simulation results, the numerical predictions for the expansion ratio and the pressure drop of a tapered fluidized bed were compared with experimental data and good agreement was observed. The obtained simulation results...