فهرست مطالب

Chemical Engineering - Volume:14 Issue: 4, Autumn 2017

Iranian journal of chemical engineering
Volume:14 Issue: 4, Autumn 2017

  • تاریخ انتشار: 1396/09/30
  • تعداد عناوین: 7
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  • S. Hosseini, H. Hashemipour Rafsanjani, A.R. Talebizadeh * Pages 3-16
    An alumina-supported nickel catalyst was prepared by impregnation of Ni2 solution onto mesoporous alumina under microwave irradiation (denoted as M-Ni/Al2O3). For comparison, a catalyst with the same nickel content was prepared by conventional impregnation method (denoted as UM-Ni/Al2O3). Both M-Ni/Al2O3 and UM-Ni/Al2O3 catalysts were applied to the syngas (H2 CO) production by methane oxy-steam reforming in order to investigate the effect of preparation method on the catalytic performance. The reaction experiments were performed in a fixed-bed continuous flow reactor under atmospheric pressure. M-Ni/Al2O3 catalyst exhibited higher methane conversion (XCH4: 0.94) than UM-Ni/Al2O3 (XCH4: 0.58) in the oxy-steam reforming reaction. In addition, the value of syngas yield in M-Ni/Al2O3 (3.21 mole per mole of methane) was almost twice of one for UM-Ni/Al2O3 catalyst (1.59 mole per mole of methane). Various operating conditions such as the influences of the O2/CH4 and H2O/CH4 feed ratios, temperature, and GHSV on the methane conversion and yield of products were investigated. According to the structural characterization (FTIR, XRD, N2 adsorption/desorption, H2-TPR and TEM), the excellent catalytic performance of M-Ni/Al2O3 catalyst was reasonably attributed to the nano size and uniform distributed nickel species (
    Keywords: methane oxy, steam reforming, Microwave, impregnation method, Ni, Al2O3
  • Mo. H. Almasvandi, M. Rahimi * Pages 17-31
    This paper reports the results of experimentally removing ammonia from synthetically prepared ammonia solution using a micro scale mixing loop air stripper. Effects of various operational parameters (such as: pH, air flow rate, wastewater flow rate and initial ammonia concentration) were evaluated. By increasing the pH from 10 to 12.25 the amount of KLa increased from 0.26 to 0.73 hr-1. A considerable enhancement, about 150%, can be found for KLa by changing the air flow rate from 280 to 700 mL/min under fixed condition. The wastewater flow rate can also the value of KLa from 0.22 to 0.59 hr-1. The values of KLa increased only about 20% by changing the initial concentration of ammonia in the range between 50 and 500 mg/L. The results showed that improving in air stripping using microchannel was successfully carried out with enhancing overall volumetric mass transfer coefficient (KLa) and providing higher mass transfer capabilities compared with other types of strippers, even for lower amounts of used air. The enhancement of mass transfer is happened by efficient mixing induced by the employed microchannel. It has been demonstrated that wastewater flow rate and air flow rate have significant effects on KLa. The optimal stripping conditions and mathematical modeling for ammonia removal and the relation between the parameters were determined using Response Surface Methodology (RSM) with Central Composite Design (CCD) method. The results demonstrate the advantages the proposed system over convention stripper types.
    Keywords: air stripping, ammonia, microchannel, optimization, overall volumetric mass transfer
  • E. Ghasemikafrudi *, M. Amini, M. R. Habibi Pages 32-47
    The effects of greenhouse gases (GHG) on the growth of global warming, and increase of GHG and air pollutant emissions for energy production have forced the need of energy recovery which is normally wasted in industrial plant. The present research work focused on the GHG and air pollutant emissions reduction employing pressure waste energy recovery. Pressure break-down via Joule-Thomson valve is a neat potential for waste energy recovery in gas refineries, which may also be provide by using a turbo-expander instead of commercial valves. Based on this ground, an exergy analysis is carried out for Joule-Thomson valve. The results showed that the exergy loss is higher than 6.5 MW and it is possible to recover about 1.9 MW of exergy loss. On the other hand, it was found that about 16900MWh of electrical energy can be produced by recovering the energy of waste pressure, which may leads to less consumption of the load and gas in refinery power unit. Consequently, equal the gas consumption reduction, 12056 ton CO2e of GHG and 54.6 ton of air pollutant emissions is reduced annually. Economical evaluation of utilizing a turbo-expander instead of a valve proved that this altering scenario is deducible and practical. Economical indexes, namely, IRR and NPV are found to be equal to 25.51% and 929571 US$, respectively. Moreover, sensitivity analysis conducted on each specific state certified the obtained results.
    Keywords: Waste pressure recovery, Greenhouse gases, Joule, Thomson process, Exergy analysis, Turbo, expander
  • L. Mahmoodi, B. Vaferi *, M. Kayani Pages 48-58
    Temperature distribution is a key function for analyzing and optimizing the thermal behavior of various process equipments. Moving bed reactor (MBR) is one of the high-tech process equipment which tries to improve the process performance and its energy consumption by fluidizing solid particles in a base fluid. In the present study, thermal behavior of MBR has been analyzed through mathematical simulation. Good agreement between the obtained results and both experimental data and analytical solution by self-adjoint method is observed. Mathematical results confirm that the average particle temperature linearly increases across the reactor length. Fluid temperature changes in a parabolic manner, and then it changes linearly. Increasing the Biot number ( ) results in increasing the temperature gradient inside the particle to a maximum value, and thereafter a decreasing pattern is observed. The numerical results confirmed that the finite difference method can be used for thermal analysis of the moving bed reactor.
    Keywords: moving bed reactor, mathematical simulation, thermal analysis, temperature profile
  • M. Saeedi, O. Vahidi * Pages 59-79
    In this paper, we simulate magnetic hyperthermia process on a mathematical phantom model representing cancer tumor and its surrounding healthy tissues. The temperature distribution throughout the phantom model is obtained by solving the bio-heat equations and the consequent cell death amount is calculated using correlations between the tissue local temperature and the cell death rate. To have an estimate of heat generated from typical magnetic nanoparticles, magnetite nanoparticles are synthesized and the heat dissipation amount from the synthesized nanoparticles exposed to an alternating magnetic field is measured and used in the computer simulation. The impact of the amount of heat generated from the magnetic nanoparticles exposed to an alternating magnetic field, their distribution patterns in the tumor and hyperthermia process duration time on the cell death rate in both cancer and healthy tissues are investigated. It is indicated that while various factors contributing in the heat dissipation amount from the magnetic nanoparticles are important in the effectiveness of the magnetic hyperthermia process, the distribution pattern plays the major role in determining the efficiency of the process.
    Keywords: Magnetic hyperthermia, Magnetic nanoparticles, Mathematical phantom model, Nanoparticles distribution pattern, Tissue cells death rate
  • J. Pandey, A. Verma, R. Patel, Sh. Srivastava * Pages 77-89
    The present paper deals with the kinetics and mechanism of homogeneously Ir(III) chloride catalyzed oxidation of D-mannitol by chloramine-T [CAT] in perchloric acid medium in the temperature range of 30 to 45 0C. The reaction is carried out in the presence of mercuric acetate as a scavenger for chloride ion. The experimental results show first order kinetics with respect to the oxidant [CAT] and catalyst [Ir(III)] while zero order with respect to substrate, i.e., D-Mannitol was observed. The reaction shows negligible effect of [Hg(OAc)2], [H] and ionic strength of the medium. Chloride ion positively influence the rate of reaction. The reaction between chloramine-T and D-Mannitol in acid medium shows 2:1 stoichiometry. To calculate activation parameters, the reactions have been studied at four different temperatures between 30 to 45ºC. A mechanism involving the complex formation between catalyst and oxidant has been proposed. Mannonic acid has been identified chromatographically and spectroscopically as the final product of oxidation of D-Mannitol. Based on the kinetic data, reaction stoichiometry and product analysis, a reaction mechanism has been proposed and rate law has been derived.
    Keywords: Kinetics, mechanism, Ir(III) catalysis, D, Mannitol, chloramine, T, acidic medium
  • E. Gomaa *, A. Negm, R. Abou Qurn Pages 90-99
    The redox behavior cobalt chloride was studied voltammetrically in presence and absence of L- Carrageenan (LK) natural polymer using glassy carbon electrodes in 0.1 M KCl supporting electrode. Scan rates are studied for the redox behaviors for CoCl2 alone or in presence of L- Carrageenan (LK) natural polymer. Stability constants for the interaction of cobalt ions with L - Carageenan (LK) natural polymer are evaluated. All mechanisms are discussed.The redox behavior cobalt chloride was studied voltammetrically in presence and absence of L- Carrageenan (LK) natural polymer using glassy carbon electrodes in 0.1 M KCl supporting electrode. The interaction of CoCl2 with L-Carrageenan (LK) has been studied using cyclic voltammetry technique in the potential range (.5 to -1.0) V at different scan rates in water at 292.15 oK using KCl (0.1M) as supporting medium and glassy carbon as a working electrode. The study is valuable for evaluating the thermodynamic properties [3-18]. The cobalt ions used show two oxidation peak at 0.02 and 0.06 V and two reduction peaks at 0 and -0.7 V These two peaks corresponding to the oxidation of cobalt zero valent to monovalent and then the oxidation of cobalt monovalent to divalent cobalt Scan rates are studied for the redox behaviors for CoCl2 alone or in presence of L- Carrageenan (LK) natural polymer. Stability constants for the interaction of cobalt ions with L - Carageenan (LK) natural polymer are evaluated. All mechanisms are discussed.
    Keywords: Cyclic voltammetry, cobalt chloride, glassy carbon electrode, L Carageenan