In this study, the effect of different carbon sources on the carbothermal reduction of low-grade phosphate ore were examined using FactSage7.2 calculations and vacuum reduction experiments. The thermodynamic calculations showed that the trend of the effect for three types of reducing agents was generally consistent under 1 Pa pressure and 14% carbon dosage. The reduction effect was maximum when graphite was used as the reducing agent, and a maximum mass of P was obtained at 1250 ?C. The vacuum experiment results showed that the reduction and volatilization ratios of phosphate rock increased with temperature for different carbon sources. Maximum reduction ratio was obtained using graphite in the temperature range 1250-1300?C. The reduction effect of pulverized coal was optimal at 1350?C, when SiO2, Al2O3, and MgO in the pulverized coal ash were exposed to form low-melting eutectics with CaO due to the increased degree of reaction, and the heat and mass transfer rates were increased. At this time, a maximum reduction ratio of 51.77% of the sample and a maximum volatilization ratio of 82.44% of P were achieved. Considering the cost effectiveness, pulverized coal was the optimum carbon source for the treatment of low-grade phosphate rock using vacuum carbothermal reduction.
{"title":"Effect of different carbon sources on vacuum carbothermal reduction of low-grade phosphorus ore","authors":"X. He, Run Huang","doi":"10.2298/CICEQ210219013H","DOIUrl":"https://doi.org/10.2298/CICEQ210219013H","url":null,"abstract":"In this study, the effect of different carbon sources on the carbothermal reduction of low-grade phosphate ore were examined using FactSage7.2 calculations and vacuum reduction experiments. The thermodynamic calculations showed that the trend of the effect for three types of reducing agents was generally consistent under 1 Pa pressure and 14% carbon dosage. The reduction effect was maximum when graphite was used as the reducing agent, and a maximum mass of P was obtained at 1250 ?C. The vacuum experiment results showed that the reduction and volatilization ratios of phosphate rock increased with temperature for different carbon sources. Maximum reduction ratio was obtained using graphite in the temperature range 1250-1300?C. The reduction effect of pulverized coal was optimal at 1350?C, when SiO2, Al2O3, and MgO in the pulverized coal ash were exposed to form low-melting eutectics with CaO due to the increased degree of reaction, and the heat and mass transfer rates were increased. At this time, a maximum reduction ratio of 51.77% of the sample and a maximum volatilization ratio of 82.44% of P were achieved. Considering the cost effectiveness, pulverized coal was the optimum carbon source for the treatment of low-grade phosphate rock using vacuum carbothermal reduction.","PeriodicalId":9716,"journal":{"name":"Chemical Industry & Chemical Engineering Quarterly","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68462021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Srinivasan Manikandan Periasamy, Nesakumar Dharmakkan, N. Sumana
The experimental study of heat transfer coefficient of nanofluid plays a significant role in improving the heat transfer rate of the heat exchanger. The research was conducted in a natural convection heat transfer apparatus by suspending Al2O3 nanoparticle in a base fluid of Water-Ethylene glycol mixture. The effects of heat input (A), nanoparticle volume fraction (B), and base fluid concentration (C) on experimental heat transfer coefficient (hexpnf) were studied. By the results obtained by MINITDesign software 23 full factorial design matrix, 16 experimental runs were performed with the lower and higher level of input factors. The levels for heat input are 10 and 100 W; nanoparticle volume fraction is 0.1 and 1 volume% and for base fluid concentration is 30 and 50 volume% of Ethylene Glycol in water. From the obtained experimental results residual plots, Pareto chart, contour plot and 3D surface plots were drawn. It can be found from the study that the experimental heat transfer coefficient showed highest enhancement with high level of nanoparticle volume fraction and moderate enhancement with high level of heat input and slight enhancement with base fluid concentration.
{"title":"Heat transfer studies of Al2O3/water-ethylene glycol nanofluid using factorial design analysis","authors":"Srinivasan Manikandan Periasamy, Nesakumar Dharmakkan, N. Sumana","doi":"10.2298/CICEQ210125021M","DOIUrl":"https://doi.org/10.2298/CICEQ210125021M","url":null,"abstract":"The experimental study of heat transfer coefficient of nanofluid plays a significant role in improving the heat transfer rate of the heat exchanger. The research was conducted in a natural convection heat transfer apparatus by suspending Al2O3 nanoparticle in a base fluid of Water-Ethylene glycol mixture. The effects of heat input (A), nanoparticle volume fraction (B), and base fluid concentration (C) on experimental heat transfer coefficient (hexpnf) were studied. By the results obtained by MINITDesign software 23 full factorial design matrix, 16 experimental runs were performed with the lower and higher level of input factors. The levels for heat input are 10 and 100 W; nanoparticle volume fraction is 0.1 and 1 volume% and for base fluid concentration is 30 and 50 volume% of Ethylene Glycol in water. From the obtained experimental results residual plots, Pareto chart, contour plot and 3D surface plots were drawn. It can be found from the study that the experimental heat transfer coefficient showed highest enhancement with high level of nanoparticle volume fraction and moderate enhancement with high level of heat input and slight enhancement with base fluid concentration.","PeriodicalId":9716,"journal":{"name":"Chemical Industry & Chemical Engineering Quarterly","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68462468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A commercial low-density polyethylene (LDPE) which is produced by the polymerization process of ethylene in the presence of initiators in a long tubular reactor is the most widely used in polymer industry. The highly exothermic nature of the LDPE polymerization process and the heating-cooling prerequisite in the tubular reactor can lead to various problems, particularly safety in terms of thermal runaway and productivity, i.e., decreasing monomer conversion. Therefore, model-based optimization of an industrial LDPE tubular reactor under thermal safety consideration is required to be implemented. A first principle model for this process is developed and validated using industrial data. Mass and energy balances have been derived from kinetics of LDPE polymerization. Thereafter, an expression of reactor temperature under critical condition is developed and incorporated in the reference model for the thermal safety study. In order to ensure the process is thermally safe and meets the desired product grade, the constrained dynamic optimization is proposed to maximize the conversion of the monomer using orthogonal collocation (OC). The dynamic optimization result shows that the maximum reaction temperature under critical condition constraint can be satisfied by optimizing the reactor jacket. Moreover, it is achieved without jeopardizing the monomer conversion and the product grade.
{"title":"Dynamic optimization of low-density polyethylene production in tubular reactor under thermal safety constraint","authors":"A. Azmi, S. A. Sata, F. S. Rohman, N. Aziz","doi":"10.2298/ciceq190108027a","DOIUrl":"https://doi.org/10.2298/ciceq190108027a","url":null,"abstract":"A commercial low-density polyethylene (LDPE) which is produced by the polymerization process of ethylene in the presence of initiators in a long tubular reactor is the most widely used in polymer industry. The highly exothermic nature of the LDPE polymerization process and the heating-cooling prerequisite in the tubular reactor can lead to various problems, particularly safety in terms of thermal runaway and productivity, i.e., decreasing monomer conversion. Therefore, model-based optimization of an industrial LDPE tubular reactor under thermal safety consideration is required to be implemented. A first principle model for this process is developed and validated using industrial data. Mass and energy balances have been derived from kinetics of LDPE polymerization. Thereafter, an expression of reactor temperature under critical condition is developed and incorporated in the reference model for the thermal safety study. In order to ensure the process is thermally safe and meets the desired product grade, the constrained dynamic optimization is proposed to maximize the conversion of the monomer using orthogonal collocation (OC). The dynamic optimization result shows that the maximum reaction temperature under critical condition constraint can be satisfied by optimizing the reactor jacket. Moreover, it is achieved without jeopardizing the monomer conversion and the product grade.","PeriodicalId":9716,"journal":{"name":"Chemical Industry & Chemical Engineering Quarterly","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68458700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Al-Yaqoobi, Muna N. Al-Rikabey, M. Al-Mashhadani
The cost of microalgae harvesting constitutes a heavy burden on the commercialization of biofuel production. The present study addressed this problem through economic and parametric comparison of electrochemical harvesting using a sacrificial electrode (aluminum) and a nonsacrificial electrode (graphite). The harvesting efficiency, power consumption, and operation cost were collected as objective variables as a function of applied current and initial pH of the solution. The results indicated that high harvesting efficiency obtained by using aluminum anode is achieved in short electrolysis time. That harvesting efficiency can be enhanced by increasing the applied current or the electrolysis time for both electrode materials, where 98% of harvesting efficiency can be obtained. The results also demonstrated that the power consumption with the graphite anode is higher than that of aluminum. However, at 0.2 A the local cost of operation with graphite (0.036 US$/m3) is distinctly lower than that of aluminum (0.08 US$/m3). Furthermore, the harvesting efficiency reached its higher value at short electrolysis time at an initial pH of 6 for aluminum, and at an initial pH of 4 for graphite. Consequently, the power consumption of the harvesting process could be reduced at acid- nature conditions to around 0.46 kWh/kg for aluminum and 1.12 kWh/kg for graphite.
{"title":"Electrochemical harvesting of microalgae꞉ Parametric and cost-effectivity comparative investigation","authors":"A. Al-Yaqoobi, Muna N. Al-Rikabey, M. Al-Mashhadani","doi":"10.2298/ciceq191213031a","DOIUrl":"https://doi.org/10.2298/ciceq191213031a","url":null,"abstract":"The cost of microalgae harvesting constitutes a heavy burden on the commercialization of biofuel production. The present study addressed this problem through economic and parametric comparison of electrochemical harvesting using a sacrificial electrode (aluminum) and a nonsacrificial electrode (graphite). The harvesting efficiency, power consumption, and operation cost were collected as objective variables as a function of applied current and initial pH of the solution. The results indicated that high harvesting efficiency obtained by using aluminum anode is achieved in short electrolysis time. That harvesting efficiency can be enhanced by increasing the applied current or the electrolysis time for both electrode materials, where 98% of harvesting efficiency can be obtained. The results also demonstrated that the power consumption with the graphite anode is higher than that of aluminum. However, at 0.2 A the local cost of operation with graphite (0.036 US$/m3) is distinctly lower than that of aluminum (0.08 US$/m3). Furthermore, the harvesting efficiency reached its higher value at short electrolysis time at an initial pH of 6 for aluminum, and at an initial pH of 4 for graphite. Consequently, the power consumption of the harvesting process could be reduced at acid- nature conditions to around 0.46 kWh/kg for aluminum and 1.12 kWh/kg for graphite.","PeriodicalId":9716,"journal":{"name":"Chemical Industry & Chemical Engineering Quarterly","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68460370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cláudia Cavalcanti Jéssica, João Paulo, L. Stragevitch, de Rodrigues Carvalho, Maria Pimentel Fernanda
In this work, the ethanol fuel dehydration process was optimized using the Aspen Plus? simulator and a multivariate statistical technique based on the desirability function. The suitability of the ionic liquids 1-methylimidazolium chloride ([Mim][Cl]), 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]), 1-butyl- -3-methylimidazolium chloride ([Bmim][Cl]) and 1-hexyl-3-methylimidazolium chloride ([Hmim][Cl]), as extractive distillation entrainers, was also evaluated and compared to the conventional solvents, ethylene glycol and cyclohexane. Among the solvents studied, [Mim][Cl] required the lowest energy consumption, about 8% less energy use when compared to the optimized process using ethylene glycol. The multivariate statistical techniques employed were effective in the optimization of the extractive distillation processes as the process energy consumption could be minimized while achieving ethanol purity in agreement with the current specifications as well as obtaining a high solvent recovery. With the desirability approach it was possible to improve the process performance with little or no modification of existing processing plants.
{"title":"Multivariate statistical optimization of the ethanol fuel dehydration process using ionic liquids","authors":"Cláudia Cavalcanti Jéssica, João Paulo, L. Stragevitch, de Rodrigues Carvalho, Maria Pimentel Fernanda","doi":"10.2298/ciceq200410035c","DOIUrl":"https://doi.org/10.2298/ciceq200410035c","url":null,"abstract":"In this work, the ethanol fuel dehydration process was optimized using the Aspen Plus? simulator and a multivariate statistical technique based on the desirability function. The suitability of the ionic liquids 1-methylimidazolium chloride ([Mim][Cl]), 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]), 1-butyl- -3-methylimidazolium chloride ([Bmim][Cl]) and 1-hexyl-3-methylimidazolium chloride ([Hmim][Cl]), as extractive distillation entrainers, was also evaluated and compared to the conventional solvents, ethylene glycol and cyclohexane. Among the solvents studied, [Mim][Cl] required the lowest energy consumption, about 8% less energy use when compared to the optimized process using ethylene glycol. The multivariate statistical techniques employed were effective in the optimization of the extractive distillation processes as the process energy consumption could be minimized while achieving ethanol purity in agreement with the current specifications as well as obtaining a high solvent recovery. With the desirability approach it was possible to improve the process performance with little or no modification of existing processing plants.","PeriodicalId":9716,"journal":{"name":"Chemical Industry & Chemical Engineering Quarterly","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68460859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shama Hayder Mustafa, S. Hussain, W. Ahmad, M. Jahanzaib, Abaid Ullah
Water pollution has become a serious issue of this century due to increased industrialization. Several methods have been adopted to tackle this issue, including adsorption by activated carbon (AC). Conventional sources of AC preparation are costly and non-renewable as well. Several fruit and agricultural wastes have characteristics to become sustainable feedstock for AC preparation. This study aims to prepare cost effective AC from sustainable raw material, cow dung. The preparation has been analyzed and optimized by utilizing central composite design (CCD). The effect of activation temperature, time, and impregnation ratio (IR) on responses of percent yield ( R1) and percent pesticide removal (R2) has been analyzed. Quadratic models have been suggested with R2, adjusted R2, and predicted R2 values of 0.98, 0.96, 0.89 for R1, and 0.97, 0.94, 0.87 for R2, respectively. Activation temperature and KOH/Feedstock ratio significantly influence the yield and pesticide removal. Optimized conditions of activation temperature, KOH/Feedstock ratio, and activation time are 708.07 ?C, 1.22 and 0.66 h, respectively. These conditions produced 14.78% yield and 89.18% pesticide removal. SEM and BET analysis of optimized AC also confirmed porosity development and large surface area availability due to activation process. Findings of this study suggest that cow dung can be used to prepare low-cost AC for pesticide removal from aqueous solution.
{"title":"Optimization of low-cost cow dung based activated carbon for the removal of carbofuran from aqueous solution","authors":"Shama Hayder Mustafa, S. Hussain, W. Ahmad, M. Jahanzaib, Abaid Ullah","doi":"10.2298/ciceq200427033h","DOIUrl":"https://doi.org/10.2298/ciceq200427033h","url":null,"abstract":"Water pollution has become a serious issue of this century due to increased industrialization. Several methods have been adopted to tackle this issue, including adsorption by activated carbon (AC). Conventional sources of AC preparation are costly and non-renewable as well. Several fruit and agricultural wastes have characteristics to become sustainable feedstock for AC preparation. This study aims to prepare cost effective AC from sustainable raw material, cow dung. The preparation has been analyzed and optimized by utilizing central composite design (CCD). The effect of activation temperature, time, and impregnation ratio (IR) on responses of percent yield ( R1) and percent pesticide removal (R2) has been analyzed. Quadratic models have been suggested with R2, adjusted R2, and predicted R2 values of 0.98, 0.96, 0.89 for R1, and 0.97, 0.94, 0.87 for R2, respectively. Activation temperature and KOH/Feedstock ratio significantly influence the yield and pesticide removal. Optimized conditions of activation temperature, KOH/Feedstock ratio, and activation time are 708.07 ?C, 1.22 and 0.66 h, respectively. These conditions produced 14.78% yield and 89.18% pesticide removal. SEM and BET analysis of optimized AC also confirmed porosity development and large surface area availability due to activation process. Findings of this study suggest that cow dung can be used to prepare low-cost AC for pesticide removal from aqueous solution.","PeriodicalId":9716,"journal":{"name":"Chemical Industry & Chemical Engineering Quarterly","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68460900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Neto Silva Daniel, Ferreira Loz Paulo, João Soletti Inácio, Dayana Coêlho de
To produce biodiesel, one of the most important factors is the quality of the oil used in the production. However, other factors such as price and availability should also be taken into consideration. Chicken wastes oil shows a very promising option for this sector, since it comes from a waste. The aim of the present study was a methodology for extraction and characterization of chicken wastes oil for production of biodiesel by ethylic transesterification, besides presenting the characterization and optimization of the process variables of the production of biodiesel, the applying of RSM involving CCD. The investigation was performed following evaluation of the characterization parameters for the oil: viscosity, density, acidity index, moisture of the sample, refractive index, and saponification index. For biodiesel, viscosity, density, acidity index and ester content were evaluated. An optimum point was reached for the production of chicken biodiesel where the concentration of the catalyst is 2.1% by mass, the oil/ethanol ratio is 1:5.5 and the reaction temperature of 30 ?C; at that point, a 95% conversion was achieved. At the optimum point obtained from the statistical technique for a p-value of 0.05 the results found for the physical- chemical characterization of biodiesel are found in the ANP standards.
{"title":"Factorial design and surface method to optimization ethylic biodiesel production from chicken wastes","authors":"Neto Silva Daniel, Ferreira Loz Paulo, João Soletti Inácio, Dayana Coêlho de","doi":"10.2298/ciceq191117034s","DOIUrl":"https://doi.org/10.2298/ciceq191117034s","url":null,"abstract":"To produce biodiesel, one of the most important factors is the quality of the oil used in the production. However, other factors such as price and availability should also be taken into consideration. Chicken wastes oil shows a very promising option for this sector, since it comes from a waste. The aim of the present study was a methodology for extraction and characterization of chicken wastes oil for production of biodiesel by ethylic transesterification, besides presenting the characterization and optimization of the process variables of the production of biodiesel, the applying of RSM involving CCD. The investigation was performed following evaluation of the characterization parameters for the oil: viscosity, density, acidity index, moisture of the sample, refractive index, and saponification index. For biodiesel, viscosity, density, acidity index and ester content were evaluated. An optimum point was reached for the production of chicken biodiesel where the concentration of the catalyst is 2.1% by mass, the oil/ethanol ratio is 1:5.5 and the reaction temperature of 30 ?C; at that point, a 95% conversion was achieved. At the optimum point obtained from the statistical technique for a p-value of 0.05 the results found for the physical- chemical characterization of biodiesel are found in the ANP standards.","PeriodicalId":9716,"journal":{"name":"Chemical Industry & Chemical Engineering Quarterly","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68459839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The fluid dynamic and mass transfer characteristics of concentric upward gas-liquid flow were studied in an industrial static mixer with four equally spaced helical inserts (FKSM). The numerical simulations of the gas volume fraction in a Kenics mixer was in good agreement with the numerical and experimental results provided by Rabha et al. The characteristics of radial gas void fraction and local mass transfer coefficients in the FKSM were evaluated under different operating conditions. The velocity profiles of the concentric air phase accelerated by the bubble forces first became sharp and narrow until z/l = = -3.27 and then slowly decreased and stabilized at z/l = -1.5 before entering the first mixing element. Some extra unimodal profile of radial gas holdup gradually generated near the rectangle cross-sections of the mixing elements. The ?G gradually enlarged from r/R = 0.2 to r/R = 0.55 and then weakened from r/R = 0.65 to r/R = 0.874. The air void fractions in the bulk flow region decreased with the increasing initial uniform bubble diameter. The inlet effect of the first leading edge enhanced the air phase dispersion and local mass transfer coefficients sharply increased from 2.04 to 3.69 times of that in the inlet. The local mass transfer coefficients in each mixing group had unimodal profiles.
研究了四个等间距螺旋插片(FKSM)工业静态混合器内气液同心向上流动的流体动力学和传质特性。对Kenics混合器内气体体积分数的数值模拟与Rabha等人的数值和实验结果吻合较好。研究了不同工况下FKSM内径向气隙率和局部传质系数的特性。在气泡力加速下，同心气相的速度分布在z/l = = -3.27处首先变得尖细狭窄，然后在z/l = -1.5处缓慢减小并趋于稳定，进入第一个混合单元。在混合单元的矩形截面附近，逐渐产生了一些额外的径向气含率单峰分布。从r/ r = 0.2逐渐增大到r/ r = 0.55，再从r/ r = 0.65逐渐减弱到r/ r = 0.874。随着初始均匀气泡直径的增大，散流区空隙率减小。第一前缘的入口效应增强了气相弥散，局部传质系数由入口的2.04倍急剧增加到3.69倍。各混合组的局部传质系数呈单峰分布。
{"title":"The flow and mass transfer characteristics of concentric gas-liquid flow in an advanced static mixer","authors":"Huibo Meng, Zhonggen Li, Yanfang Yu, Mengqi Han, Shuning Song, Xiu-Hui Jiang, Zongyong Wang, Jianhua Wu","doi":"10.2298/ciceq191213024m","DOIUrl":"https://doi.org/10.2298/ciceq191213024m","url":null,"abstract":"The fluid dynamic and mass transfer characteristics of concentric upward gas-liquid flow were studied in an industrial static mixer with four equally spaced helical inserts (FKSM). The numerical simulations of the gas volume fraction in a Kenics mixer was in good agreement with the numerical and experimental results provided by Rabha et al. The characteristics of radial gas void fraction and local mass transfer coefficients in the FKSM were evaluated under different operating conditions. The velocity profiles of the concentric air phase accelerated by the bubble forces first became sharp and narrow until z/l = = -3.27 and then slowly decreased and stabilized at z/l = -1.5 before entering the first mixing element. Some extra unimodal profile of radial gas holdup gradually generated near the rectangle cross-sections of the mixing elements. The ?G gradually enlarged from r/R = 0.2 to r/R = 0.55 and then weakened from r/R = 0.65 to r/R = 0.874. The air void fractions in the bulk flow region decreased with the increasing initial uniform bubble diameter. The inlet effect of the first leading edge enhanced the air phase dispersion and local mass transfer coefficients sharply increased from 2.04 to 3.69 times of that in the inlet. The local mass transfer coefficients in each mixing group had unimodal profiles.","PeriodicalId":9716,"journal":{"name":"Chemical Industry & Chemical Engineering Quarterly","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68460325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The power consumption and flow patterns generated in a cylindrical stirred tank are determined. The anchor impeller is used to ensure the agitation of highly viscous fluids. Newly modifications in the impeller design are introduced to improve the stirring rates. Firstly, the lower corner of the conventional anchor is replaced by an inclined segment to obtain Case No. 1. The number of segments was then increased to reach a closed circular shape (Case No. 2). Further increase in the number of segments was introduced to reach a perfect circular blade (Case 3) in the vertical direction. Finally, another circular horizontal blade was added to obtain Case No. 4. From the obtained results, Case No. 4 provided a great improvement in the circulation of fluid particles inside the vessel and generated the widest well-stirred region.
{"title":"Newly suggested shapes of impellers for stirring highly viscous fluids in vessels","authors":"H. Ameur, Y. Kamla","doi":"10.2298/CICEQ201013005A","DOIUrl":"https://doi.org/10.2298/CICEQ201013005A","url":null,"abstract":"The power consumption and flow patterns generated in a cylindrical stirred tank are determined. The anchor impeller is used to ensure the agitation of highly viscous fluids. Newly modifications in the impeller design are introduced to improve the stirring rates. Firstly, the lower corner of the conventional anchor is replaced by an inclined segment to obtain Case No. 1. The number of segments was then increased to reach a closed circular shape (Case No. 2). Further increase in the number of segments was introduced to reach a perfect circular blade (Case 3) in the vertical direction. Finally, another circular horizontal blade was added to obtain Case No. 4. From the obtained results, Case No. 4 provided a great improvement in the circulation of fluid particles inside the vessel and generated the widest well-stirred region.","PeriodicalId":9716,"journal":{"name":"Chemical Industry & Chemical Engineering Quarterly","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68461051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Industrial sodium chlorate production is a highly energy-intensive electro-chemical process. If the pH of the chlorate cell is not controlled, the current efficiency drops from 99% to as low as 66.66%. Hence control of chlorate cell pH is very significant for energy-efficient sodium chlorate production. This study puts forward a fractional order PID controller for controlling the pH of the sodium chlorate cell. The tuning of FOPID controller variables is affected by employing particle swarm optimization. The highlight of the controller is that it is flexible, easy to deploy and the time of computation is significantly low as few parameters are needed to be adjusted in PSO. The performance analysis of the suggested FOPID-PSO controller was studied and compared with the traditional PI controller and PID controller using time-domain provisions like settling time, rise time and peak overshoot and error indicators like integral square error (ISE), integral absolute error (IAE), and integral time absolute error (ITAE). FOPID controller employing PSO proved to perform well compared to conventional controllers with 0.5 sec settling time and 0.1 sec rise time. This demonstrates that the FOPID-PSO controller has better setpoint tracking, which is very essential for the process under consideration.
{"title":"pH control in sodium chlorate cell for energy efficiency using PSO-FOPID controller","authors":"Sreepriya Sreekumar, Aparna Kallingal, Vinila Mundakkal Lakshmanan","doi":"10.2298/ciceq200911031s","DOIUrl":"https://doi.org/10.2298/ciceq200911031s","url":null,"abstract":"Industrial sodium chlorate production is a highly energy-intensive electro-chemical process. If the pH of the chlorate cell is not controlled, the current efficiency drops from 99% to as low as 66.66%. Hence control of chlorate cell pH is very significant for energy-efficient sodium chlorate production. This study puts forward a fractional order PID controller for controlling the pH of the sodium chlorate cell. The tuning of FOPID controller variables is affected by employing particle swarm optimization. The highlight of the controller is that it is flexible, easy to deploy and the time of computation is significantly low as few parameters are needed to be adjusted in PSO. The performance analysis of the suggested FOPID-PSO controller was studied and compared with the traditional PI controller and PID controller using time-domain provisions like settling time, rise time and peak overshoot and error indicators like integral square error (ISE), integral absolute error (IAE), and integral time absolute error (ITAE). FOPID controller employing PSO proved to perform well compared to conventional controllers with 0.5 sec settling time and 0.1 sec rise time. This demonstrates that the FOPID-PSO controller has better setpoint tracking, which is very essential for the process under consideration.","PeriodicalId":9716,"journal":{"name":"Chemical Industry & Chemical Engineering Quarterly","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68461313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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