International journal of engineering and technologies, Sep 1, 2018
In the present work we have studied the thermal stability, flammability, fume evolution of epoxy ... more In the present work we have studied the thermal stability, flammability, fume evolution of epoxy matrix composites with different types and amounts of hardeners, fillers, plasticizers and fire retardants. It is shown that chemical composition of fillers has little effect on the flammability of epoxy composites when the content of mineral fillers is less than 45% by mass. Smoke formation decreases linearly with increasing the degree of filling. It is shown that to obtain low-combustible materials the oxygen index should exceed 31%. It was found that the optimal concentration of industrial brominated fire retardants is 8-10% by mass. To reduce the flammability of epoxy composites, additive brominated fire retardants in the form of a solution in N,N-dimethyl-2,4,6tribromoaniline have been proposed. The high efficiency of acetyl-and α-hydroxyethyl ferrocene as a smoke suppressor of epoxy composites is shown.
Korean Journal of Chemical Engineering, Sep 1, 2009
In the computational fluid dynamics modeling of gas-solid two phase flow, drag force is one of th... more In the computational fluid dynamics modeling of gas-solid two phase flow, drag force is one of the dominant mechanisms for interphase momentum transfer. Despite the profusion of drag models, an extensive comparison is missing from the literature. In this work the drag correlations of Syamlal-O'Brien, Gidaspow, Wen-Yu, Arastoopour, Gibilaro, Di Felice, Zhang-Reese and Koch et al. are reviewed using a multifluid model of FLUENT software with the resulting hydrodynamics parameters being compared with experimental data. Also adjustment of drag models based on minimum fluidization was studied. A new method adopted to adjust the drag function of Di Felice showed a quantitative improvement compared to the adjusted drag model of Syamlal-O'Brien. Prediction of bed expansion and pressure drop showed excellent agreement with results of experiments conducted in a Plexiglas fluidized bed. A mesh size sensitivity analysis with varied interval spacing showed that mesh interval spacing with 18 times the particle diameter and using higher order discretization methods produces acceptable results.
Journal of Natural Gas Science and Engineering, 2019
The conventional method for gas sweetening is the conversion of hydrogen sulfide to solid sulfur.... more The conventional method for gas sweetening is the conversion of hydrogen sulfide to solid sulfur. Although this method has some advantages, researchers are trying to come up with more beneficial technologies. In light of this requirement, a modified experimental method based on the method previously proposed by Yermakova and Mashkina in 2004 is used in the current study. The main idea of this method is modified as the novelty of this investigation which is utilization of mixture of H 2 S, propane and butane, as a sour gas instead of pure hydrogen sulfide. Modified mathematical approach based on the model previously proposed by Yermakova and Mashkina in 2004 is used to convert the hydrogen sulfide to methyl mercaptane. In this way, in the first stage of this study, experimental investigation is performed to investigate the possible effect of three different parameters of molar ratio, mass flow rate and inlet temperature. After that the obtained results are utilized to mathematically model the proposed sweetening method. The overall results demonstrated that although application of H 2 S mixtures leads to lower conversion rate of H 2 S to methyl mercaptane due to lower partial pressure of H 2 S regarding the presence of impurities of propane and butane, the catalytic conversion of H 2 S to valuable chemicals can be an applicable and feasible tool for industrial purposes.
In this study, results of revamping of stabilizer unit of a refinery which includes a debutanizer... more In this study, results of revamping of stabilizer unit of a refinery which includes a debutanizer, and a splitter column, are presented. The products of the unit are light straight run gasoline (LSRG) and Heavy straight run gasoline (HSRG). Revamping has been carried out by commercial software. Results of simulation illustrate that revamping by structured packings is an effective method for capacity increase while maintain product quality at the same time. Debutanizer and splitter units have been simulated with regard to inlet and outlet flow rates, flooding, operating pressure and temperature. The simulation results are in good agreement with the operating data and experimental analysis. By using MELLAPAK 250X, as a structured packing in revamping process, pressure drop was decreased from 196 to 23 mbar. In addition, Sichlmair model has predicted the pressure drop very accurately. The results also demonstrate 31% capacity increase in feed flow rate and higher quality product.
Microencapsulation of liquid orange oil as a common flavoring agent in food industries by complex... more Microencapsulation of liquid orange oil as a common flavoring agent in food industries by complex coacervation in a gelatin - gum Arabic polymeric wall system was studied. At a fixed ratio of 10% w/v as concentration of the materials used in this study, trend of changes of microencapsulation process variables using different wall polymeric contents along with varying levels of the core to wall ratio were investigated. Distribution pattern of the coacervate particle size showed that more than 70% of the particle with the average diameter of 9.68 mm were reasonably encapsulated in those treatments having core to wall ratio at the level of 1:1 and 1:2 while gelatin to gum arabic content of the wall system were set to be 1:1 and 2:1 ratio, respectively. The yield of the process as ratio of the amount of coacervate microcapsules produced to the amount of materials initially present in the emulsion was highest (69%) for the treatment described. Moreover, the release and swelling data have been analyzed in terms of the generalized equation Mt/M∞=kt n applicable for swellable controlled release systems. The results obtained were discussed on the basis of the release rate constant k, and diffusional exponent n.
Chemeca 2004: 32nd Australasian Chemical Engineering Conference: Sustainable Processes, 2004
Microencapsulation of liquid orange oil as a common flavoring agent in food industries by complex... more Microencapsulation of liquid orange oil as a common flavoring agent in food industries by complex coacervation in a gelatin - gum arabic polymeric wall system was studied. At a fixed ratio of 10% w/v as concentration of the materials used in this study, different polymeric contents along with three levels of the core to wall ratio were investigated. Distribution pattern of the coacervate particle size showed that more than 70% of the particle with the average diameter of 9.68 mm reasonably were encapsulated in those treatments having core to wall ratio at the level of 1:1 and 1:2 while gelatin to gum arabic content of the wall system were set to be 1:1 and 2:1 ratio. The yield of the process as ratio of the amount of coacervate microcapsules produced to the amount of materials initially present in the emulsion was highest and about 69% for that treatment having core to wall ratio of 1:2 having gelatin to gum arabic at the 2:1 level. Moreover, the release and swelling data have been analyzed in terms of the generalized equation applicable for the swellable controlled release systems. The results obtained were discussed on the basis of the release rate constant k, and diffusional exponent n.
جداکنندههای گرانشی چند فازی یکی از پرکاربردترین تجهیزات برای جدایش فازهای غیرقابل امتزاج در صنا... more جداکنندههای گرانشی چند فازی یکی از پرکاربردترین تجهیزات برای جدایش فازهای غیرقابل امتزاج در صنایع مختلف به شمار میروند. در این کار به بهبود عملکرد یک جداکننده گرانشی سه فازی صنعتی دارای بوت، با هدف رفع مشکلاتی که از عیبیابی فرایند جدایش در این جداکننده بدست آمده، پرداخته شده است. بدینمنظور، اثر تعویض هدایتکننده در ورودی (نوع پرهدار به جای ورودی زاویهدار)، نصب بافل در میانه و نمگیر در انتهای جدا کننده مورد بررسی قرار گرفت. نتایج این تحقیق نشان داد که با استفاده از طراحی جدید، عملکرد جداکننده بهبود یافته، به طوری که میزان مایع در گاز خروجی% 8/83 نسبت به طراحی کنونی در صنعت کاهش یافته است. این طراحی در بهبود رفتار جریان در ناحیه ورودی، بهبود توزیع اندازه قطرات در خروجی و همچنین در جلوگیری از کاهش چشمگیر عملکرد جداکننده هنگام افزایش دبی، که از مشکلات مربوط به عیبیابی فرایند جدایش بودهاند، نیز موفق عمل کرده است.
Entrepreneurs' decision-making process is one of the main research topics in entrepreneurship stu... more Entrepreneurs' decision-making process is one of the main research topics in entrepreneurship studies. This research aims to conceptualize the antecedents of new venture creation decision in Iranian high tech industries. The research utilizes an innovative non-teleological approach in order to take into account the specific regional context of Iran. Most research into entrepreneurial decision making utilizes teleological approaches; however, these models could not adequately explain the phenomena within the Iranian context. This qualitative study utilized event-based interviews with 20 nascent entrepreneurs. Results from coding, categorizing and validating the research findings, revealed 3 main categories as antecedents of new venture creation decision. Accordingly, concepts of entrepreneurial meta-cognition; primary actions and receiving feedback; and positive attitude toward change, constitute the main antecedents of new venture creation decision in this context. The findings also reveal the non-teleological nature of entrepreneurial decision-making, and adoption of some effectuation logics in the studied decision-making process.
Design of experiment was conducted to study the effect of alumina micro particles as a ceramic fi... more Design of experiment was conducted to study the effect of alumina micro particles as a ceramic filler alone or along with two other ceramic fillers, boehmite and silicon carbide, on curing characteristics as well as the mechanical and thermo-physical properties of carbon black filled butyl rubber-based curing tire bladder composite. The effect of using silane coupling agent, X50S as well as increasing the polarity and stiffness of the polymer matrix by replacing the butyl rubber with chlorobutyl were also investigated. Examination of rheometry curing behavior of rubber compounds showed that alumina has a slight reduction effect on curing rate and maximum torque, which improves with the presence of the modifier, X50S. Boehmite showed a reducing effect on curing rate and maximum torque while the performance of silicon carbide was similar to that alumina. Also, the hardness of the composite increased with the presence of alumina similar to that SiC and decreased with the presence of bo...
Advances in environmental science and technology, 2018
This paper describes the feasibility of replacing a sulfur-based additive with the waste by-produ... more This paper describes the feasibility of replacing a sulfur-based additive with the waste by-product disulfide oil (DSO) in steam cracking for the production of olefin. The objective of adding this substance is to reduce coke formation, and consequently, prevent its formation on the inner walls of the reactor and heat exchanger. It is reported that dimethyl sulfide (DMDS) is a source of hydrogen sulfide, and it is hydrogen sulfide that minimizes coke formation, even though the mechanism is not clear. Disulfide oil is a waste material in gas refineries and a source for hydrogen sulfide production; therefore, it makes sense to evaluate its efficacy in minimizing CO production and coke formation during olefin production. Therefore, pilot plant runs were performed to evaluate its feasibility. By using disulfide oil, the total sulfur content of the pyrolysis gasoline will change and be equal to 26.89 mg/L for the unit with a capacity production of 18000 kg/hr. This action not only provide...
Spinning Cone Columns (SCC) are new distillation columns which have found a wide application for ... more Spinning Cone Columns (SCC) are new distillation columns which have found a wide application for the flavour separation and recovery. From the notable advantages of these columns in comparison with the conventional columns, their low pressure drop, high mass transfer efficiency, and ability to handle feeds which contain a high proportion of suspended solids can be mentioned. The modeling and estimation of liquid film thickness for the calculation of mass transfer coefficient is very important, since mass transfer occurs between the liquid and gas films flowing countercurrent on the rotating and stationary cones. For estimation of liquid film thickness, the Nusselt and Makarytchev models are used.They show errors of about 7% and 30% in comparison with the experimental values, respectively. The mass transfer coefficients in the liquid phase (kL ) are also calculatad using these models. The results show, the error in calculation of kL are around 500% and 250% by using the Makarytchev a...
The distillation process remains as the most common method ofseparation in chemical process indus... more The distillation process remains as the most common method ofseparation in chemical process industries. The energy used from this process accounts for an estimated 3% of the world energy consumption. The Dividing-Wall Column (DWC) for separation of multi-component mixtures has recently become a major concern ofindustries. The design ofDWC is based on Thermally Coupled Distillation System (TCDS) eliminating some of the operational equipment. This paper presents the results of simulation of a DWC by using 3-simple sequence column model based on shortcut method by a commercial chemical Engineering software for purification of1,3 butadiene unit. From the results, it is shown, by using a DWC instead of two conventional sequential column, the heat duties ofboth the condenser and the reboiler are reduced about 28.5% and also desirable purity ofthe key-components for the case ofstudy have been achieved.
International journal of engineering and technologies, Sep 1, 2018
In the present work we have studied the thermal stability, flammability, fume evolution of epoxy ... more In the present work we have studied the thermal stability, flammability, fume evolution of epoxy matrix composites with different types and amounts of hardeners, fillers, plasticizers and fire retardants. It is shown that chemical composition of fillers has little effect on the flammability of epoxy composites when the content of mineral fillers is less than 45% by mass. Smoke formation decreases linearly with increasing the degree of filling. It is shown that to obtain low-combustible materials the oxygen index should exceed 31%. It was found that the optimal concentration of industrial brominated fire retardants is 8-10% by mass. To reduce the flammability of epoxy composites, additive brominated fire retardants in the form of a solution in N,N-dimethyl-2,4,6tribromoaniline have been proposed. The high efficiency of acetyl-and α-hydroxyethyl ferrocene as a smoke suppressor of epoxy composites is shown.
Korean Journal of Chemical Engineering, Sep 1, 2009
In the computational fluid dynamics modeling of gas-solid two phase flow, drag force is one of th... more In the computational fluid dynamics modeling of gas-solid two phase flow, drag force is one of the dominant mechanisms for interphase momentum transfer. Despite the profusion of drag models, an extensive comparison is missing from the literature. In this work the drag correlations of Syamlal-O'Brien, Gidaspow, Wen-Yu, Arastoopour, Gibilaro, Di Felice, Zhang-Reese and Koch et al. are reviewed using a multifluid model of FLUENT software with the resulting hydrodynamics parameters being compared with experimental data. Also adjustment of drag models based on minimum fluidization was studied. A new method adopted to adjust the drag function of Di Felice showed a quantitative improvement compared to the adjusted drag model of Syamlal-O'Brien. Prediction of bed expansion and pressure drop showed excellent agreement with results of experiments conducted in a Plexiglas fluidized bed. A mesh size sensitivity analysis with varied interval spacing showed that mesh interval spacing with 18 times the particle diameter and using higher order discretization methods produces acceptable results.
Journal of Natural Gas Science and Engineering, 2019
The conventional method for gas sweetening is the conversion of hydrogen sulfide to solid sulfur.... more The conventional method for gas sweetening is the conversion of hydrogen sulfide to solid sulfur. Although this method has some advantages, researchers are trying to come up with more beneficial technologies. In light of this requirement, a modified experimental method based on the method previously proposed by Yermakova and Mashkina in 2004 is used in the current study. The main idea of this method is modified as the novelty of this investigation which is utilization of mixture of H 2 S, propane and butane, as a sour gas instead of pure hydrogen sulfide. Modified mathematical approach based on the model previously proposed by Yermakova and Mashkina in 2004 is used to convert the hydrogen sulfide to methyl mercaptane. In this way, in the first stage of this study, experimental investigation is performed to investigate the possible effect of three different parameters of molar ratio, mass flow rate and inlet temperature. After that the obtained results are utilized to mathematically model the proposed sweetening method. The overall results demonstrated that although application of H 2 S mixtures leads to lower conversion rate of H 2 S to methyl mercaptane due to lower partial pressure of H 2 S regarding the presence of impurities of propane and butane, the catalytic conversion of H 2 S to valuable chemicals can be an applicable and feasible tool for industrial purposes.
In this study, results of revamping of stabilizer unit of a refinery which includes a debutanizer... more In this study, results of revamping of stabilizer unit of a refinery which includes a debutanizer, and a splitter column, are presented. The products of the unit are light straight run gasoline (LSRG) and Heavy straight run gasoline (HSRG). Revamping has been carried out by commercial software. Results of simulation illustrate that revamping by structured packings is an effective method for capacity increase while maintain product quality at the same time. Debutanizer and splitter units have been simulated with regard to inlet and outlet flow rates, flooding, operating pressure and temperature. The simulation results are in good agreement with the operating data and experimental analysis. By using MELLAPAK 250X, as a structured packing in revamping process, pressure drop was decreased from 196 to 23 mbar. In addition, Sichlmair model has predicted the pressure drop very accurately. The results also demonstrate 31% capacity increase in feed flow rate and higher quality product.
Microencapsulation of liquid orange oil as a common flavoring agent in food industries by complex... more Microencapsulation of liquid orange oil as a common flavoring agent in food industries by complex coacervation in a gelatin - gum Arabic polymeric wall system was studied. At a fixed ratio of 10% w/v as concentration of the materials used in this study, trend of changes of microencapsulation process variables using different wall polymeric contents along with varying levels of the core to wall ratio were investigated. Distribution pattern of the coacervate particle size showed that more than 70% of the particle with the average diameter of 9.68 mm were reasonably encapsulated in those treatments having core to wall ratio at the level of 1:1 and 1:2 while gelatin to gum arabic content of the wall system were set to be 1:1 and 2:1 ratio, respectively. The yield of the process as ratio of the amount of coacervate microcapsules produced to the amount of materials initially present in the emulsion was highest (69%) for the treatment described. Moreover, the release and swelling data have been analyzed in terms of the generalized equation Mt/M∞=kt n applicable for swellable controlled release systems. The results obtained were discussed on the basis of the release rate constant k, and diffusional exponent n.
Chemeca 2004: 32nd Australasian Chemical Engineering Conference: Sustainable Processes, 2004
Microencapsulation of liquid orange oil as a common flavoring agent in food industries by complex... more Microencapsulation of liquid orange oil as a common flavoring agent in food industries by complex coacervation in a gelatin - gum arabic polymeric wall system was studied. At a fixed ratio of 10% w/v as concentration of the materials used in this study, different polymeric contents along with three levels of the core to wall ratio were investigated. Distribution pattern of the coacervate particle size showed that more than 70% of the particle with the average diameter of 9.68 mm reasonably were encapsulated in those treatments having core to wall ratio at the level of 1:1 and 1:2 while gelatin to gum arabic content of the wall system were set to be 1:1 and 2:1 ratio. The yield of the process as ratio of the amount of coacervate microcapsules produced to the amount of materials initially present in the emulsion was highest and about 69% for that treatment having core to wall ratio of 1:2 having gelatin to gum arabic at the 2:1 level. Moreover, the release and swelling data have been analyzed in terms of the generalized equation applicable for the swellable controlled release systems. The results obtained were discussed on the basis of the release rate constant k, and diffusional exponent n.
جداکنندههای گرانشی چند فازی یکی از پرکاربردترین تجهیزات برای جدایش فازهای غیرقابل امتزاج در صنا... more جداکنندههای گرانشی چند فازی یکی از پرکاربردترین تجهیزات برای جدایش فازهای غیرقابل امتزاج در صنایع مختلف به شمار میروند. در این کار به بهبود عملکرد یک جداکننده گرانشی سه فازی صنعتی دارای بوت، با هدف رفع مشکلاتی که از عیبیابی فرایند جدایش در این جداکننده بدست آمده، پرداخته شده است. بدینمنظور، اثر تعویض هدایتکننده در ورودی (نوع پرهدار به جای ورودی زاویهدار)، نصب بافل در میانه و نمگیر در انتهای جدا کننده مورد بررسی قرار گرفت. نتایج این تحقیق نشان داد که با استفاده از طراحی جدید، عملکرد جداکننده بهبود یافته، به طوری که میزان مایع در گاز خروجی% 8/83 نسبت به طراحی کنونی در صنعت کاهش یافته است. این طراحی در بهبود رفتار جریان در ناحیه ورودی، بهبود توزیع اندازه قطرات در خروجی و همچنین در جلوگیری از کاهش چشمگیر عملکرد جداکننده هنگام افزایش دبی، که از مشکلات مربوط به عیبیابی فرایند جدایش بودهاند، نیز موفق عمل کرده است.
Entrepreneurs' decision-making process is one of the main research topics in entrepreneurship stu... more Entrepreneurs' decision-making process is one of the main research topics in entrepreneurship studies. This research aims to conceptualize the antecedents of new venture creation decision in Iranian high tech industries. The research utilizes an innovative non-teleological approach in order to take into account the specific regional context of Iran. Most research into entrepreneurial decision making utilizes teleological approaches; however, these models could not adequately explain the phenomena within the Iranian context. This qualitative study utilized event-based interviews with 20 nascent entrepreneurs. Results from coding, categorizing and validating the research findings, revealed 3 main categories as antecedents of new venture creation decision. Accordingly, concepts of entrepreneurial meta-cognition; primary actions and receiving feedback; and positive attitude toward change, constitute the main antecedents of new venture creation decision in this context. The findings also reveal the non-teleological nature of entrepreneurial decision-making, and adoption of some effectuation logics in the studied decision-making process.
Design of experiment was conducted to study the effect of alumina micro particles as a ceramic fi... more Design of experiment was conducted to study the effect of alumina micro particles as a ceramic filler alone or along with two other ceramic fillers, boehmite and silicon carbide, on curing characteristics as well as the mechanical and thermo-physical properties of carbon black filled butyl rubber-based curing tire bladder composite. The effect of using silane coupling agent, X50S as well as increasing the polarity and stiffness of the polymer matrix by replacing the butyl rubber with chlorobutyl were also investigated. Examination of rheometry curing behavior of rubber compounds showed that alumina has a slight reduction effect on curing rate and maximum torque, which improves with the presence of the modifier, X50S. Boehmite showed a reducing effect on curing rate and maximum torque while the performance of silicon carbide was similar to that alumina. Also, the hardness of the composite increased with the presence of alumina similar to that SiC and decreased with the presence of bo...
Advances in environmental science and technology, 2018
This paper describes the feasibility of replacing a sulfur-based additive with the waste by-produ... more This paper describes the feasibility of replacing a sulfur-based additive with the waste by-product disulfide oil (DSO) in steam cracking for the production of olefin. The objective of adding this substance is to reduce coke formation, and consequently, prevent its formation on the inner walls of the reactor and heat exchanger. It is reported that dimethyl sulfide (DMDS) is a source of hydrogen sulfide, and it is hydrogen sulfide that minimizes coke formation, even though the mechanism is not clear. Disulfide oil is a waste material in gas refineries and a source for hydrogen sulfide production; therefore, it makes sense to evaluate its efficacy in minimizing CO production and coke formation during olefin production. Therefore, pilot plant runs were performed to evaluate its feasibility. By using disulfide oil, the total sulfur content of the pyrolysis gasoline will change and be equal to 26.89 mg/L for the unit with a capacity production of 18000 kg/hr. This action not only provide...
Spinning Cone Columns (SCC) are new distillation columns which have found a wide application for ... more Spinning Cone Columns (SCC) are new distillation columns which have found a wide application for the flavour separation and recovery. From the notable advantages of these columns in comparison with the conventional columns, their low pressure drop, high mass transfer efficiency, and ability to handle feeds which contain a high proportion of suspended solids can be mentioned. The modeling and estimation of liquid film thickness for the calculation of mass transfer coefficient is very important, since mass transfer occurs between the liquid and gas films flowing countercurrent on the rotating and stationary cones. For estimation of liquid film thickness, the Nusselt and Makarytchev models are used.They show errors of about 7% and 30% in comparison with the experimental values, respectively. The mass transfer coefficients in the liquid phase (kL ) are also calculatad using these models. The results show, the error in calculation of kL are around 500% and 250% by using the Makarytchev a...
The distillation process remains as the most common method ofseparation in chemical process indus... more The distillation process remains as the most common method ofseparation in chemical process industries. The energy used from this process accounts for an estimated 3% of the world energy consumption. The Dividing-Wall Column (DWC) for separation of multi-component mixtures has recently become a major concern ofindustries. The design ofDWC is based on Thermally Coupled Distillation System (TCDS) eliminating some of the operational equipment. This paper presents the results of simulation of a DWC by using 3-simple sequence column model based on shortcut method by a commercial chemical Engineering software for purification of1,3 butadiene unit. From the results, it is shown, by using a DWC instead of two conventional sequential column, the heat duties ofboth the condenser and the reboiler are reduced about 28.5% and also desirable purity ofthe key-components for the case ofstudy have been achieved.
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