Process Control and Engineering, Process Safety, HSE
Volume 6, Issue 4 , October 2009, , Pages 27-33
Abstract
In low-temperature processes, heat rejected from separation columns is removed by refrigeration systems to heat sinks (reboilers & pre-heaters), process streams, other refrigeration streams, or external utilities. The need for efficient utilization and recovery of energy in sub-ambient gas separation ...
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In low-temperature processes, heat rejected from separation columns is removed by refrigeration systems to heat sinks (reboilers & pre-heaters), process streams, other refrigeration streams, or external utilities. The need for efficient utilization and recovery of energy in sub-ambient gas separation processes is still challenging. Performance and reliability of Simulated Annealing (SA) for simultaneous design and optimization of such systems has been investigated previously. In this work, the effect of different refrigerants satisfying a set of process cooling duties at different temperatures is addressed. Cost reduction can be realized by encompassing both effective screening of heat-integrated separation columns and selecting the best refrigerants. A 29.7% cost savings has been shown through a case study. Afterwards, a comprehensive thermodynamic analysis has been carried out on achieved solutions to verify the accuracy of existing shortcut models and robustness of optimized structure. It has been shown that exergy analysis using two different approaches (i.e. stream wise and unit operation wise) are the same, which indicate the accuracy of the used models. Moreover, we have indicated that both utility costs and exergy losses can be considered as an objective function when optimizing the designs.
Separation Technology,
N. Mostafazadeh; A.A. Ghoreyshi; K. Pirzadeh
Volume 15, Issue 4 , November 2018, , Pages 27-47
Abstract
In this study, ZIF-67 was synthesized through solvothermal method to remove Cr(VI) ions from aqueous solution. To improve the structural properties of ZIF-67 and its adsorption capacity, optimization of the synthesis conditions was carried out based on maximum Cr(VI) uptake. From experiments, the optimum ...
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In this study, ZIF-67 was synthesized through solvothermal method to remove Cr(VI) ions from aqueous solution. To improve the structural properties of ZIF-67 and its adsorption capacity, optimization of the synthesis conditions was carried out based on maximum Cr(VI) uptake. From experiments, the optimum condition was revealed as solvent: metal ion molar ratio of 4.6:1, ligand: metal ion molar ratio of 318:1 and temperature of 23℃. The physio-chemical properties of as-synthesized ZIF-67 were investigated by BET, XRD, FTIR and FESEM analyses. Effect of adsorption pH, adsorbent dosage, initial concentration and contact time on adsorption process was investigated. Based on the results, the maximum adsorption capacity of Cr(VI) was 26.27 mg/g which was obtained at 35℃, pH= 5, adsorbent dosage of 3 g/l and initial concentration of 107.82 mg/l. The equilibrium time for Cr(VI) adsorption varied from 180 min for low initial concentration of 9 mg/L to 240 min for a high initial concentration of 90 mg/L. For the synthesized ZIF-67, maximum uptake capacity was reported 26.27 mg/g at initial concentration of 107.82 mg/l. The equilibrium data were described better by Langmuir-Freundlich isotherm model than the other models at three different temperatures. Pseudo-second-order model fitted the experimental data better than pseudo-first-order one. Adsorption thermodynamics indicated that the adsorption process was endothermic and spontaneous in nature. The regenerability of ZIF-67 was also studied in three sequential cycles and the Cr(VI) adsorption was almost retained after two cycles.
Separation Technology,
Volume 10, Issue 4 , October 2013, , Pages 28-42
Biomedical and Biotechnology,
Volume 7, Issue 2 , April 2010, , Pages 28-38
Separation Technology,
Volume 7, Issue 1 , January 2010, , Pages 28-41
Materials synthesize and production
M. Ghasemi; A. A. Ghoreyshi; H. Younesi; S. Khoshhal Khoshhal
Volume 12, Issue 4 , October 2015, , Pages 28-51
Abstract
A high performance activated carbon was synthesized using walnut shell as a solid waste through a two-step zinc chloride chemical activation-thermal pyrolysis process. Characterization results demonstrated its porous structure with very good textural properties such as high BET surface area (1223 m2/g) ...
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A high performance activated carbon was synthesized using walnut shell as a solid waste through a two-step zinc chloride chemical activation-thermal pyrolysis process. Characterization results demonstrated its porous structure with very good textural properties such as high BET surface area (1223 m2/g) and high total pore volume (0.85 cm3/g). The final adsorbent was used for adsorption of Fe (II) and Cr (VI) from aqueous solution. Effect ofpH, initial concentration of metal ions, temperature, and contact time on adsorption capacity of the adsorbent was investigated. Adsorption results revealed that the maximum removal of Fe (II) and Cr (VI) ions, occurred at pH 4. 5 and 2 respectively, were 96.2% and 99% at 313K. The equilibrium and kinetics data for adsorption of single-component ions were well described by the Sips isotherm and the pseudo-nth-order models, respectively. The impact of competing ions was studied by adsorption of a binary solution of Fe (II) and Cr (VI) ions. The binary adsorption isotherm was described by the modified Langmuir model and model parameters were found following an optimization procedure by genetic algorithm. Finally, the developed walnut-shell based activated carbon showed higher adsorption efficiency compared to other activated carbons at similar conditions.
Modeling and Simulation
Volume 11, Issue 2 , April 2014, , Pages 29-42
Biomedical and Biotechnology,
Volume 8, Issue 2 , April 2011, , Pages 29-40
Reaction Engineering, Kinetics and Catalysts,
Volume 7, Issue 3 , July 2010, , Pages 29-48
Process Control and Engineering, Process Safety, HSE
Volume 6, Issue 2 , April 2009, , Pages 29-36
Modeling and Simulation
Volume 5, Issue 3 , July 2008, , Pages 29-39
Abstract
An industrial ethane thermal cracking reactor was modeled assuming a molecular mechanism for the reaction kinetics coupled with material, energy, and momentum balances of the reactant-product flow along the reactor. To carry out the multi-objective optimization for two objectives such as conversion and ...
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An industrial ethane thermal cracking reactor was modeled assuming a molecular mechanism for the reaction kinetics coupled with material, energy, and momentum balances of the reactant-product flow along the reactor. To carry out the multi-objective optimization for two objectives such as conversion and ethylene selectivity, the elitist non-dominated sorting genetic algorithm was used. The Pareto optimum set was obtained successfully and finally the effect of the decision variable was discussed.
Petroleum and Reservoir Engineering
Volume 3, Issue 1 , January 2006, , Pages 29-39
Reaction Engineering, Kinetics and Catalysts,
Volume 3, Issue 3 , July 2006, , Pages 29-43
Abstract
In this study we developed LaNixAl1-xO3 perovskite systems using a sol-gelmethod (with propionic acid as solvent) to use in methane-reforming reactions for producing synthesis gas. To understand the roles of the nature of the precursor and calcination conditions on the formation of LaNixAl1-xO3, we carried ...
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In this study we developed LaNixAl1-xO3 perovskite systems using a sol-gelmethod (with propionic acid as solvent) to use in methane-reforming reactions for producing synthesis gas. To understand the roles of the nature of the precursor and calcination conditions on the formation of LaNixAl1-xO3, we carried out identifications using NMR, FT-IR, XRD, SEM, and TEM. The precursor structure is a function of raw materials and calcination conditions. Nitrate salts of nickel, aluminium, and lanthanum, and calcinations at 750ºC for 4 h gave pure LaNixAl1-xO3 perovskite with good homogeneity, even at nanoscopic scales. These systems are highly efficient catalysts in steam and the dry reforming of methane. Various ratios of hydrogen to carbon monoxide in synthesis gas can be achieved by changing the feed type. We also investigated stabilization of these systems by studying the perovskite structure after reactivity tests. The optimum mixed perovskite for steam and dry reforming of methane is LaNi0.3Al0.7O3. The total conversion of CH4 is rapidly obtained at 750°C in steam reforming with a H2O/CH4 ratio = 3, the selectivity of CO is lower (55%) and the yield of hydrogen (98%) is higher compared to the ratio H2O/CH4 = 1. After 170 h of reaction, no deactivation had occurred, methane conversion remained higher than 90% at 750°C and in dry reforming, methane conversion and CO yield are about 98% and 95% respectively.
Modeling and Simulation
Volume 11, Issue 1 , January 2014, , Pages 30-41
Process Control and Engineering, Process Safety, HSE
Volume 10, Issue 1 , January 2013, , Pages 30-44
Polymer Engineering and Technology,
Volume 8, Issue 3 , July 2011, , Pages 31-42
Separation Technology,
M. Jadidi; N. Etesami; M. Nasr Esfahany
Volume 14, Issue 3 , August 2017, , Pages 31-40
Abstract
In this study adsorption of Cr(VI) from aqueous solution by Fe3O4 nanoparticles was investigated. Desorption process and recovery of nanoparticles using different solutions were then carried out, and it was observed that NaOH (0.5M) can remove 90% of adsorbed chromium ions. Following the completion of ...
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In this study adsorption of Cr(VI) from aqueous solution by Fe3O4 nanoparticles was investigated. Desorption process and recovery of nanoparticles using different solutions were then carried out, and it was observed that NaOH (0.5M) can remove 90% of adsorbed chromium ions. Following the completion of adsorption/ desorption cycles, it was determined that nanoparticles have still had a high ability of chromium ions adsorption after 4 cycles. In addition, it was found that when iron oxide nanoparticles were washed with NaOH solution, the adsorption efficiency increases in the next cycle. FTIR spectra and zeta potential analysis, demonstrated the increased in surface positively charged of nanoparticles leads to increased electrostatic attraction forces between the iron oxide nanoparticles and chromium ions which finally resulted in adsorption increasing. So in this research, pretreatment of nanoparticles with NaOH solution modifies the surface of Fe3O4 nanoparticles by increasing surface positively charged mechanism and the adsorption efficiency has improved in the next cycle.
Thermodynamics,
Gh. Moradi; H. Hemmati
Abstract
The Dry Reforming of Methane, which uses methane and carbon dioxide, the two greenhouse gasses, to produce synthesis gas, has received considerable attention recently. In this work, the equilibrium conversion that is the maximum possible conversion has been obtained experimentally and theoretically. ...
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The Dry Reforming of Methane, which uses methane and carbon dioxide, the two greenhouse gasses, to produce synthesis gas, has received considerable attention recently. In this work, the equilibrium conversion that is the maximum possible conversion has been obtained experimentally and theoretically. The equilibrium concentration for the Dry Reforming of Methane (DRM) has been calculated using Thermodynamic equilibrium and compared with the experimental equilibrium concentration. The reaction coordinate (ε), Gibbs free energy (G), reaction equilibrium constant (K), and reaction stoichiometric coefficients are used for the calculation of the reaction progress and the equilibrium composition in DRM at different temperatures. These parameters have been calculated by two primary methods, direct and Lagrange, and compared with an empirical equilibrium that has been revealed by the activity test on Ni/Al2O3 catalyst. The result shows that none of those can’t make an exact determination of empirical equilibrium compositions, but there was a relatively good agreement between the Lagrange method and the empirical equilibrium. No significant difference has been observed between these methods and empirical conditions at high temperature.
Petroleum and Reservoir Engineering
M. Basiri; M. Rahimi; F. Mohammadi
Volume 12, Issue 3 , July 2015, , Pages 32-40
Abstract
"> In the present study, transesterification of soybean oil to Fatty Acid Methyl Ester (FAME) was carried out in the microreactor. The system performance was investigated in the presence of hexane as a cosolvent. Furthermore, the effect of number of micromixer’s inlets on the mixing was one ...
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"> In the present study, transesterification of soybean oil to Fatty Acid Methyl Ester (FAME) was carried out in the microreactor. The system performance was investigated in the presence of hexane as a cosolvent. Furthermore, the effect of number of micromixer’s inlets on the mixing was one of the objectives in this work. For the goals mentioned above, three different experiments were done with and without cosolvent in two and three inlet micromixers under optimum conditions. Both flow pattern observations and Gas Chromatgoraphy (GC) characterization of FAME samples demonstrated that cosolvent technique and micromixer application could significantly influence the FAME yield in biodiesel production.
Thermodynamics,
Salman Movahedirad; Ali Akbar Sarbanha; Fahimeh Sobhanian
Volume 13, Issue 3 , July 2016, , Pages 32-42
Abstract
A Laser Induced Fluorescence technique (LIF) has been used to study the mixing behavior of two emerging streams in a T-Type mixing chamber. A mixing index on the basis of digital image light intensities is calculated. It has been shown that averaging over more than 800 images leads to a stable mixing ...
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A Laser Induced Fluorescence technique (LIF) has been used to study the mixing behavior of two emerging streams in a T-Type mixing chamber. A mixing index on the basis of digital image light intensities is calculated. It has been shown that averaging over more than 800 images leads to a stable mixing index calculation. Moreover, the effect of equal and un-equal flow rates on the mixing behavior of the streams has been studied. The results show that the histograms of the light intensity changes from double peak (unmixed) to a single peak (mixed) at high elevations of the chamber. Mixing index has a linear descending behavior moving toward the cell front wall and it was shown that the mixing index can be reduced up to 50% moving from cell center to near wall region. Moreover, there is a transition zone in both equal and un-equal fluid flow rates in mixing index. It was shown that the third component velocity play an important role in mixing behavior in T-Type mixing chamber.
Petroleum and Reservoir Engineering
M. Nikpour; M. Pazouki
Volume 13, Issue 1 , January 2016, , Pages 32-46
Abstract
In this essay, lipase from Burkholderia cepacia was immobilized into 3-glycidoxypropyltrimethoxysilane (GPTMS) and tetramethoxysilane (TMOS) derived sol-gels. GPTMS:TMOS molar ratio of 1:3 was found to yield the best result. The morphological characteristics were investigated based on SEM and BET analysis. ...
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In this essay, lipase from Burkholderia cepacia was immobilized into 3-glycidoxypropyltrimethoxysilane (GPTMS) and tetramethoxysilane (TMOS) derived sol-gels. GPTMS:TMOS molar ratio of 1:3 was found to yield the best result. The morphological characteristics were investigated based on SEM and BET analysis. Sample mean pore diameter was 39.1 nm, it had a specific surface area of 60 m2/g prior to enzyme addition which decreased to 7.49 m2/g after immobilization. The enzyme activity was assessed through transesterification of waste cooking oil in the presence of ethanol with optimal conditions of: 40 ᵒC, 15 % immobilized lipase, 9:1 alcohol to oil molar ratio in 24 h of reaction which resulted to 91.70 % biodiesel production. In six-hour reaction time, 86.87 % biodiesel was obtained which is much shorter than conventional enzymatic transesterification which is 72 hours. Ethyl esters were characterized by determining their viscosity, density, and flash point based on ASTM D 6751-07b standards.
Energy
E. GhasemiKafrudi; M. Amini; M. R. Habibi
Volume 14, Issue 4 , December 2017, , Pages 32-47
Abstract
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 ...
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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.
Energy
A. Mirahmad; S.M. Sadrameli; A. Jamekhorshid
Volume 13, Issue 2 , April 2016, , Pages 33-45
Abstract
Abstract Energy crisis is a major challenge in the current world. Latent heat thermal energy storage (LHTES) systems are known as equipment with promising performance by which thermal energy can be recovered. In the present study a comprehensive theoretical and experimental investigation is performed ...
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Abstract Energy crisis is a major challenge in the current world. Latent heat thermal energy storage (LHTES) systems are known as equipment with promising performance by which thermal energy can be recovered. In the present study a comprehensive theoretical and experimental investigation is performed on a LHTES system containing PEG1000 as phase change material (PCM). Discussed topics can be categorized in three parts. At first, a one dimensional mathematical model is introduced for a heat exchanger containing flat slabs of PCM. To consider the latent heat of phase change, effective heat capacity is used in the model. Secondly, through eight experiments designed by using factorial method, effects of inlet air velocity and temperature on the outlet stream is investigated. The results proved that having a determined temperature difference between inlet air and the PCM in both hot and cold cycles can enhance the efficiency. Finally, the feasible applications of a LHTES system for controlling the temperature swing in a greenhouse is studied numerically and the results are compared with experimental values. As a result, by using this passive coolant system diurnal internal temperature can be reduced for 10 °C.
Process Control and Engineering, Process Safety, HSE
Rahbar Rahimi; Shirin Boulaqhi; Amir Ziarifar
Volume 13, Issue 4 , November 2016, , Pages 33-45
Abstract
Simulation of a process and analysis of its resulting data in both dynamic and steady-state conditions are fundamental steps in understanding the process in order to design and efficient control of system as well as implementing operational cost reduction scheme. In the present paper, steady and unsteady ...
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Simulation of a process and analysis of its resulting data in both dynamic and steady-state conditions are fundamental steps in understanding the process in order to design and efficient control of system as well as implementing operational cost reduction scheme. In the present paper, steady and unsteady state simulation of Amir Kabir1, 3 butadiene purification units has been done by using Aspen and Aspen Dynamic software together with the Peng- Robinson equation of state to investigate the system responses to the disturbances. In the unsteady state simulation mode; the flow rates, pressure, temperature and level (FPTL) were controlled by Proportional-Integral-Derivative (PID) controllers in the unit. Finally, transient responses to changes such as feed temperature, feed flow rates, steam flow rates and the duties of the re-boiler of columns in unit were gained. For reaching to purified 1,3 butadiene, sensitivity of the process to the fluctuations of feed temperature and on the duties of the re-boilers of the columns is noticeable .
Modeling and Simulation
E. Pashai; M. R. Dehghani; F. Feyzi
Volume 14, Issue 2 , 2017, , Pages 33-47
Abstract
Varnish and sludge formation are considered as one of the most common problems in lubrication and hydraulic systems. In order to simulate the condition of sludge formation, base stock lubricant (Group 1 API) has been selected and exposed to heat in a laboratory setup. Sludge formation process accelerated ...
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Varnish and sludge formation are considered as one of the most common problems in lubrication and hydraulic systems. In order to simulate the condition of sludge formation, base stock lubricant (Group 1 API) has been selected and exposed to heat in a laboratory setup. Sludge formation process accelerated in the laboratory scale and solid liquid equilibrium data were extracted. Then solid-liquid equilibrium has been modeled using SAFT equation of state through sludge formation. The results for prediction of sludge formation showed that the absolute average deviations between experimental and theoretical results were less than 1.4%. The calculated results for solubility coefficient of the oxidation byproducts from SN100 (solvent neutral Group I) base stock in fresh (un-oxidized) oil were in good agreement with the experimental data, and average deviation between calculated and experimental data was less than 6.5%. The amount obtained for binary interaction parameter K_ij was – 0.0447. It is shown that SAFT equation of state has the capability of solid liquid equilibrium.