توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Selection of Drilling Muds Using Well Hydraulic Calculations
نویسنده(ها): ، ،
اطلاعات انتشار: یازدهمین کنگره ملی مهندسی شیمی ایران، سال
تعداد صفحات: ۱۱
One of the most important factors which affects mud selecting is the rheology conditions of mud, which has the role of controlling the well hydrodynamic behaviors such as pressure drops through the string pipes, bit, annulus, upraised mud pressure (UMP) and cuttings movement from the depth. In this study a computer program has been prepared to calculate the density and viscosity (or rheological index) of mud. This program has been developed based on the pressure drop equations and the settling velocity equation of the cuttings for Bingham and power law fluids in a reverse procedure to find density and viscosity of drilling mud. A combined algorithm has been prepared to solve these strongly bad behavior equations. The results have been compared with the assumed values in direct hydraulic calculations and a maximum error of 0.14% has been observed.<\div>

۲Simulation of SO2 absorption in a venturi scrubber
نویسنده(ها): ،
اطلاعات انتشار: شانزدهمین کنفرانس سالانه مهندسی مکانیک، سال
تعداد صفحات: ۷
In this study, a three dimensional mathematical model has been developed to simulate gas absorption in a venturi scrubber. The model is based on a non–uniform droplets concentration distribution which is predicted from a dispersion model in the gas flow. Also the mass transfer process will be described by dividing the whole liquid phase into drops and film. In this model, the flow in venturi scrubber is supposed to be similar to the
annular two phase flow. This is a flow pattern that includes a flow of liquid film layer on the walls and a flow of gas and liquid drops in the core. The experimental data of Viswanathan et al. [1], for distribution of droplets across the cross section of scrubber, was used to determine the value of Peclet number. In order to check the accuracy of mathematical model for gas absorption the experimental data of Johnstone et al. [2] and the Office of Air Programs, Environmental Protection Agency [3] for SO2 removal by alkaline solution and H2O are used.<\div>

۳A neural network for predicting collection efficiency using genetic algorithm in venturi scrubbers
نویسنده(ها): ،
اطلاعات انتشار: پنجمین کنگره بین المللی مهندسی شیمی، سال
تعداد صفحات: ۱۲
In this study, for the first time attempt has been made to design a neural network architecture using genetic algorithm for predicting collection efficiency in venturi scrubbers. A GA– ANN model is created using experimental data including particle diameter, throat gas velocity, liquid to gas flow rate ratio, throat hydraulic diameter and pressure drop across venturi scrubber. A good agreement has been seen between the experimental data and the model results. Comparison of the results of GA– ANNs with the trial and error method indicates that GA approach is more efficient. The effect of operating parameters such as liquid to gas flow rate ratio, throat gas velocity and particle diameter on the collection efficiency are also investigated here.<\div>

۴Kinetics of Sulfate Ions Removal from Wastewater in Fixed Bed Column Using an Anion–Exchange Resin
نویسنده(ها): ، ،
اطلاعات انتشار: پنجمین کنگره بین المللی مهندسی شیمی، سال
تعداد صفحات: ۱۰
In this work removal of sulfate ions from industrial wastewater by anion–exchange resin is studied experimentally. The equilibrium data obtained in this study have been found to fit the Freundlich adsorption isotherms. The effects of various important and influencing parameters such as flow rate, bed height and inlet adsorbate concentration on breakthrough curve are studied in detail. Also it is shown that the adsorption of sulfate ion on Lewatit K6362 resin follows reversible first–order kinetics. The overall rate constants were estimated for different initial concentrations.<\div>

۵Simulation of Settler’s Launder of Sarcheshmeh Copper Complex Using Computational Fluid Dynamics
اطلاعات انتشار: ششمین کنگره بین المللی مهندسی شیمی، سال
تعداد صفحات: ۶
In this study, computational fluid dynamics (CFD) modeling has been applied to study the behavior of organic–aqueous dispersion on performance of copper solvent extraction settler’s launder in Sarcheshmeh Copper Complex. The simulations have been carried out with an Eulerian–Eulerian method in conjunction with the incorporated MUSIG model which is based on a population balance equation and takes into account the break up and coalescence models of droplets. Effect of picket fence on the launder performance and pressure drop of the picket fences in settler launder have been investigated. The model predicts that by setting the picket fences, flow pattern becomes uniform, laminar andturbulent eddies disappear, so, phase separation improves. By increasing the number of picket fences, phase entrainment decreases and pressure drop increases.<\div>

۶Prediction of pressure drop in venturi scrubbers using a combined CFD–Population balance approach
نویسنده(ها): ،
اطلاعات انتشار: سومین کنفرانس ملی کاربرد CFD در صنایع شیمیایی، سال
تعداد صفحات: ۱۴
Venturi scrubbers is one of the most important devices controlling the air pollution. The most important factor that affects the collection efficiency in these devices is pressure drop. There are different models to predict pressure drop in venturi scrubbers. In this study, a computational fluid dynamics simulation based on Eulerain–Eulerain two–phase method has been applied to predict pressure drop in venturi scrubbers. This simulation uses MUSIG (multiple size group model) as population balance model for the droplet size distribution. Population balance model takes into account the break up and coalescence of droplets. The continuity and momentum equations and population balance model have been solved by finite volume method in the environment of ANSYS CFX 11 software for calculating the pressure drop.In order to calculate the velocity distribution of gas and droplets, the standard k–ε turbulence flow model with inclusion of buoyancy, drag, lift and turbulent dispersion forces has been used. The simulation results have been compared with the experimental data to check the accuracy of the CFD work. The simulation results are in good agreement with the experimental data.<\div>

۷Investigation of the effect of clay nanoparticles on oil recovery factor during polymer flooding in a sand packed model
اطلاعات انتشار: چهاردهمین کنگره ملی مهندسی شیمی ایران، سال
تعداد صفحات: ۶
There are several proper methods for increasing the sweep efficiency in carbonate reservoirs i.e.increase the injection phase viscosity, wettability alteration of the rock, lowering the interfacialtension and decreasing mobility ratio. The mechanism of enhanced oil recovery by dispersed nanoparticles during polymer flooding, is not well known. In this study, a series of injectionexperiments were performed in Sandpack models after saturation with water and Fahlian light oil.Two different fluids i.e. Polyacrylamide solution and dispersed clay nanoparticles in polyacrylamid solution were used as injection fluids. The result showed that the polymer solutionincreased oil recovery to 10% while the clay nanoparticles in polymer solution caused enhancedoil recovery up to 12% . This research showed that higher viscosity of displacing fluid resulted in more efficient displacement; that is, as the viscosity of displacing fluid was increased, mobilityratio was decreased and displacement efficiency was increased. also the results showed that using the claynanoparticles during polymer flooding increased polymer strength at high temprature and salinity.<\div>

۸Developing a Model Based on a Hybrid Neural Particle Swarm Optimization for Prediction of Dew Point Pressure
نویسنده(ها): ، ،
اطلاعات انتشار: سومین کنگره ملی مهندسی نفت، سال
تعداد صفحات: ۱۹
Dew point pressure is one of the most important parameters to characterize gas condensate reservoirs. Experimental determination of dew point pressure (DDP) in a window PVT cell is often difficultespecially in case of lean retrograde gas condensate. Therefore, searching for fast and robust algorithms for determination of DPP isusually needed. Despite of the wide range of applications and flexibility of ANNs in petroleum industries, design and structural optimization ofneural networks is still strongly dependent upon the designer's experience. To mitigate this problem, this paper presents a newapproach based on a hybrid neural particle swarm optimization to determine the DPP. Then, equations for DPP prediction by using theoptimized weights of network have been generated. With the obtained correlation, the user may use such results without a running the ANNsoftware. Consequently, this new model is compared with results obtained using other conventional models to make evaluation among different techniques. The results show that the hybrid model can be applied effectively and afford high accuracy and dependability for DPP forecasting for the wide range of gas properties and reservoir temperatures.<\div>

۹Prediction of Thermal conductivity of nanofluids by molecular dynamic simulation
اطلاعات انتشار: هفتمین کنگره ملی مهندسی شیمی، سال
تعداد صفحات: ۱۲
A theoretical approach based on molecular dynamics modeling, for the estimation of the thermal conductivity of liquids by the introduction of nanofuids is proposed. Algorithms are developed for simulating the nanofluid abiding the procedural steps of the molecular dynamics method. The method is presented as a solution to the generic problem of thermal conductivity enhancement of liquids in the presence of nanoparticles, and illustrated using a specific simulation procedure with properties representing using nanoparticles. In the present work we prepare water molecules in initial FCC structure and we assumed an initial velocity for molecules and used calculated potential energy balance and the Newton’s second law of motion to figure the intermolecular forces and calculated the electrostatic interactions between water molecules by Ewald sum method and it gave a potential energy 1.5 times bigger than Sankar et al.’s work. The calculation of thermal conductivity using the molecular dynamics simulation is compared with Maxwell model, Sankar et al.’s work and experimental data by the errors of 4.1% , 1.6% and 12% respectively.<\div>

۱۰Laboratory study of sulfate ions reduction from an industrial wastewater by nanofiltration process
نویسنده(ها): ، ،
اطلاعات انتشار: هفتمین کنگره ملی مهندسی شیمی، سال
تعداد صفحات: ۹
In this study, the performance of nanofiltration process using NF33–1812–50 membrane for reduction of sulfate anion from an industrial wastewater has been investigated. The effects of pressure, temperature, volume flow rate, and sulfate concentration in feed were studied. For this purpose, sulfate concentration has been selected between 400–500 ppm, and the pressure range was between 20–80 psi. To prepare artificial wastewater, Sodium Sulfate, Sodium Hydroxide andAcetic Acid were used. The results showed that the reduction of sulfate anions is possible with the upper limit. The removal rate was between 96–99%. By increasing the pressure and temperature, this rate increases, and at upper concentration this level decreases. In this study, the optimumprocess conditions were at pressure of 50 psi, temperature of 25ºC, and feed flow rate of 4 L\min. At these conditions an industrial wastewater was used; the reduction efficiency of sulfate anion was 97.34%.<\div>

۱۱Comparative Evaluation of Numerical and Gaussian Models for Gas Pollutants Dispersion from Industrial Flares
نویسنده(ها): ، ،
اطلاعات انتشار: هفتمین کنگره ملی مهندسی شیمی، سال
تعداد صفحات: ۹
A comparative evaluation of numerical and Gaussian models was developed for gas pollutants dispersion from industrial flares. Numerical model incorporates the finite volume method to estimate pollutants concentration from continuous sources. In this model, different profiles forwind velocity and dispersion coefficients were used depending on atmospheric stability classes.Surface roughness was also considered in numerical modeling. Pollutants concentration predicted by the presented model, were compared to those obtained by the Gaussian plume model which assumes constant wind and dispersion coefficients in vertical direction. The maximum ground level concentration agrees well in both models. However, the concentration distribution profile predicted by Gaussian model is broader than that of obtained by numerical model, due to considering effects of surface roughness in numerical model.<\div>

۱۲Determination of four herbicide residues in fruit juice and vegetable samples using a new version of dispersive liquid–liquid microextraction followed by gas chromatography–flame ionization detection
نویسنده(ها): ، ،
اطلاعات انتشار: دومین کنفرانس بین المللی یافته های نوین پژوهشی در شیمی و مهندسی شیمی، سال
تعداد صفحات: ۹
In this study, a new sample preparation method based on dispersive liquid–liquid microextraction has been developed for the extraction and preconcentration of aryloxyphenoxy–propionate herbicides from aqueous samples prior to their analysis by gas chromatography–flame ionization detection. In this method, two parallel glass tubes with different diameters and lengths are connected with a teflon stopcock and used as an extraction device. A mixture of disperser (acetone) and extraction (1–octanol) solvents is transferred into one side (narrow tube) of the extraction device and an aqueous phase containing the analytes is filled into the other side (wide tube) of it. Then the stopcock is slowly opened and the mixture of disperser and extraction solvents mixes with the aqueous phase. By this action, the extraction solvent is dispersed continuously as fine droplets into the aqueous sample and the target analytes are extracted into the fine droplets of the extraction solvent. The fine droplets move up through the aqueous phase due to its low density compared to aqueous phase and collect on the surface of the aqueous phase as an organic layer. Finally an aliquot of the organic phase is removed and injected into the separation system for analysis. Under the optimum extraction conditions, the extraction recoveries and enrichment factors ranged from 49 to 74% and 1633 to 2466, respectively. The results indicated that the developed method had many merits such as excellent extraction performance, higher EFs, more sensitive, and better repeatability. Finally the proposed method was successfully applied to determine the target herbicides in fruit juice and vegetable samples and haloxyfop–R–methyl was determined in onion sample.<\div>

۱۳A homogenous liquid–liquid extraction based on an acid–base reaction for extraction and preconcentration of some pesticide residues from aqueous samples
نویسنده(ها): ، ،
اطلاعات انتشار: دومین کنفرانس بین المللی یافته های نوین پژوهشی در شیمی و مهندسی شیمی، سال
تعداد صفحات: ۹
A simple, sensitive, and rapid sample pretreatment technique based on homogenous liquid–liquid extraction followed by gas chromatography–flame ionization detection has been developed for the extraction, preconcentration and determination of four pesticides including diazinon, oxadiazon, bromopropylate, and fenazaquin from fruit juice and vegetable samples. In this method, two parallel glass tubes with different diameters are connected with a teflon stopcock and used as an extraction device. Initially a basic organic solvent (amine) as an extraction solvent is mixed with acidified deionized water spiked with the analytes, which leads to formation of a homogenous solution. It is filled into one side of the extraction device. The other side is filled with an ammonia solution (1.9 M). Then the stopcock is opened and the solution of ammonia mixes with the aqueous phase. By this action, an acid–base reaction happens, so the homogenous solution is broken and the target analytes are extracted into the fine droplets of the organic solvent and move up through the aqueous phase which collect on the surface of the aqueous phase as a separated layer due to lower density of amine with respect to water. Then, 1 μL of the organic phase was taken and injected into the separation system for analysis. Under the optimum extraction conditions, high enrichment factors (1400–2125) and good extraction recoveries (56–85%) were obtained. The repeatability expressed as relative standard deviation, were in the ranges of 4.1–6.2 % (n = 6, C= 20 μg L–1) and 5.1–6.5% (n = 4, C= 20 μg L–1) for intra–day and inter–day precisions, respectively. Also, the method showed low limits of detection within the ranges of 0.04–0.32 μg L–1. Good repeatability, short sample preparation time and high enrichment factor are main advantages of the method.<\div>

۱۴CFD simulation of the wind flow around two buildings with k and Reynolds stress models to evaluate their effect on removing particle pollutants
اطلاعات انتشار: هفتمین کنفرانس ملی کاربرد CFD در صنایع شیمیایی و نفت، سال
تعداد صفحات: ۱۵
In recent past years scientists have carried out different simulations around buildings. In the environmental view it is important to know the removing of polluted particles by buildings. In this study a CFD simulation for the wind flow around two urban buildings were performed by three different turbulent models, namely RNG k–, Realizable k– and Reynolds stress. This was done to find the best turbulent model. The results show that the Realizable k– turbulent model has more adaptability with experimental data than the other models .The reattachment length for three models for the area between two buildings and after the second building was calculated. Finally, a wind flow containing calcium carbonate particles was modeled using Realizable k– model and the amount of removed particles by the walls of two buildings was calculated.<\div>

۱۵A New Correlation Based on Multi–Gene Genetic Programming for Predicting the Sweet Natural Gas Compressibility Factor
اطلاعات انتشار: Gas Processing Journal، سوم،شماره۱، ۲۰۱۵، سال
تعداد صفحات: ۱۰
Gas compressibility factor (z–factor) is an important parameter widely applied in petroleum and chemical engineering. Experimental measurements, equations of state (EOSs) and empirical correlations are the most common sources in z–factor calculations. However, these methods have serious limitations such as being time–consuming as well as those from a computational point of view, like instability, convergence and accuracy. Accurate and fast estimation of this parameter is of interest and a challenging factor in the numerous calculations related to oil and gas processing plants. In this study, a meta–learning algorithm named multi–gene genetic algorithm (MGGP) was applied to predict the sweet gas compressibility factor. To assess the effectiveness of the MGGP model statistical criteria, is applied. The validity of this proposed model was compared with the experimental data. The results showed that the model has successfully predicted the sweet natural gas z–factor, especially at the midrange of operating conditions. However, the MGGP model seems to be inefficient in boundary values of Tpr (i.e. around 1 and 2). In addition, the MGGP model is compared with other z–factor correlations and it is revealed that the implementation of MGGP model lead to a more accurate and reliable estimation of the natural gas compressibility factor.

۱۶Comparison of Seed Characteristics in Even–aged Accessions of Atriplex canescens under Exclosure and Non–exclosure Conditions in Rangelands of Zarand–Shahriar, Iran
اطلاعات انتشار: ECOPERSIA، دوم،شماره۱، Winter ۲۰۱۴، سال
تعداد صفحات: ۸
To compare the seed characteristics in accessions of Atriplex canescens under exclosure and non–exclosure conditions, two even–aged sites were selected with an area of 400 ha as the exclosure and 1000 ha as non–exclosure area. To conduct the study, 30 species were randomly selected in autumn 2009 in reference area of the sites and seeds were collected. Some important seed characteristics were studied in the laboratory. Data analysis was conducted using SPSS 17 software and mean comparisons were performed by Duncan''s Multiple Range Tests. Results showed that the winged seeds did not germinate under all studied treatments in both sites. Moreover, maximum seed germination was recorded for the seeds soaked in cold water for 24 hours and placed in the shade for 48 hours. According to the results of the independent t–test, no significant differences were observed for germination percentage, germination rate, and vigor index in both sites at both 1 and 5% probability levels. In other words, the seeds collected from the exclosure and non–exclosure areas were similar in terms of the mentioned characteristics. However, seed yield, 1000–seed weight and seed moisture content showed significant differences at 1% probability level with higher amount in exclosure area.
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