Sharif Digital Repository

In this study the kinetics of extraction of various hydrocarbons from crude oil using supercritical CO2 has been studied experimentally. The effect of parameters such as temperature (35, 45, 55, 65 °C), pressure (90, 110, 130, 150 bar), initial volume of crude oil (16, 19, 22, 25 mL) were investigated. Flow rate of gas has been recorded dynamically. QUALITECH 4 and MATLAB neural network softwares have been used for designing the experiments and modeling the final results, respectively. Pressure has a direct effect on extraction yield and by increasing it, heavier fractions could be obtained. On the other hand, the effect of temperature is more complicated, by increasing the temperature, the... 

In this project dynamic effect of changes in gas turbine load on power plant, reforming and Co2 capture section is investigate. The reason for study of effects change of gas turbine load is that gas turbine determines the performance of the other parts in combined cycle including gas cycle and change of gas turbine load can alter the load and the performance of other parts in the power plant and in other process such as production of synthesis gas and carbon dioxide separation unit. One Autothermal reactor and eight sewgs reactor are utilized to produce gas turbine fuel which is mainly consist of Hydrogen. this part of thesis is to be implemented in the gPROMS from process system enterprise... 

The purpose of this research is to model transport and separation of single and gas mixtures through pore network modeling in dense membranes. In the first part of the project, the mass transfer and governing mechanisms of transport are investigated. In the second part of the project, simulation of membrane pore network in 3D of Cartesian coordinate is done. In the third part of the project permeability of single gas and ideal selectivity of binary gases for an actual membrane by desired mechanism are calculated. Then the results of pore network modeling were compare with the results from molecular dynamic simulation for single gas in polyurethane membrane with reasonable agreement. In this... 

The aim of this project is to achieve a semi permeable high flux membrane with a reasonable salt rejection for the treatment of low osmotic pressure water. A thin film composite membrane consists of three polymeric layers was studied in this project. These layers were polyester support, polysulfone sub layer and polyamine selective layer. The polyester support provides the mechanical resistance against the operating pressure. The polysulfone sub layer provides the suitable area for polyamide synthesize, and the polyamide layer is the selective active layer of membrane.
The resistance to water penetration in sub layer was reduced first and then, the pores in the polyamide layer refined by... 

In this study, fabrication of polymeric nanocomposite membranes for separation of olefins from paraffins was investigated. Silver nanoparticles were prepared by Polyol chemical reduction method. At first, dense ethylcellulose and ethylcellulose-silver nanoparticles membranes were fabricated by solvent-evaporation method. Then Asymmetric EC and EC-silver nanoparticle nanocomposite membranes were fabricated by dry/wet phase inversion method as a means to improve flux rates and olefin selectivity in olefin/paraffin separations. The membranes properties and The Effects of incorporating nanoparticles in polymer matrix in low concentration on gas permeability and membranes morphology were... 

Through our work, we conducted a three-stage solution to effectively reduce the impact of 'concentration polarization' and 'fouling' on ultrafiltration process. The stages were compromise of: 1. the design and selection of appropriate equipment along with outlining the operational parameters, 2. the pretreatment process design, and 3. the cleaning process design. Because of the presence of fat, there are incline both in permeate flux and the quality of the final product. Therefore, we studied the different methods of removing the lipid content, during pretreatment stage. After examining these methods, finally, we found that adding chitosan parallel with employing centrifugal separator is the... 

During the brewing process, beer alternately goes through different chemical and biochemical reactions and solid–liquid separation stages. The clarification at the final step of brewing is a highly critical stage when it comes to producing a clear and bright beer. Recently, membrane technology has been successfully used in beer clarification, wherein Kieselguhr (diatomaceous earth) filtration is replaced by cross-flow microfiltration. The most important disadvantages of using microfiltration in clarification of beer is the fouling and flux decline during the process. The phenomenology of fouling mechanisms is still undefined and selection of an appropriate technique for flux enhancement in... 

Regarding decreasing resources of fossil fuels and their increasing costs in addition to their environmental pollutions, today, producing bio fuels from wastes such as lignocellulosic materials is of great interest. A fundamental stage in conversion of lignocellulosic materials into bio fuels, such as bio ethanol, is the enzymatic hydrolysis of these materials to produce reducing sugars. Researches have shown high costs of this stage. Optimization of enzymatic hydrolysisconditions is a major step in economization of this process.In this work corn hull is used to produce glucose. Corn hull is a kind of lignocellulosic material that due to high carbohydrate content is used as substrate. Our... 

Using membrane contactors for acid gas removal, combines the advantages of membrane based separation processes and traditional ones. In this project we aim to study the use of a membrane absorption system for sweetening gas streams containing mixed acid gases with composition similar to raw natural gas. H2S and CO2 exist in the gas stream simultaneously which can be removed by mixture of alkanolamine solvents, including MDEA, DEA and MEA, are used for treating. A lab-scale membrane absorption setup with feed capacity of 2 lit/min, was designed, constructed and commissioned. Several hollow fiber modules equipped with PSf and PVDF membranes were fabricated. Our results revealed that reaching... 

In this project, modification of reverse osmosis membrane was investigated in order to reduce the biofouling in treatment of brackish water. Furthermore, the technique which is used to attain the favorable results is graft polymerization to modify the membrane’s surface with grafting acrylic acid as hydrophilic monomer onto polyamide exploited as last layer in reverse osmosis membrane. This technique is a free radical grafting, andfree radicals which are needed for grafting are provided by the redox system potassium persulfate-sodium metabisulfite which was used as initiator. To figure out the best concentration of acrylic acid, initiator and process time in order to achieve a new membrane... 

In this thesis, the application of solar energy in the steam injection as a thermal enhanced oil recovery (TEOR) is evaluated. The motivations of this project are using a renewable energy, suitable solar potential of Iran, successful experience in the world, undeveloped heavy oilfield reservoirs in Iran. This application is investigated by three aspects which are:Reservoir Engineering aspect: the heavy oilfield are determined and then screening for selection good candidate of steam injection are done. One of the reservoirs is analyzed by simulation and optimization the steam injection to determine how much it’s production will be improved by using steam injection (contionous and cyclic)... 

A kind of novel nanofiltration membrane process is proposed to solvent recovery from dewaxed lube oil stream in an energy-saving way. Most of the nanofiltration membrane materials are polymeric and cannot survive harsh conditions, for example, MEK contained solvents. Hence, high solubility of most of the polymeric materials in the solvent, especially in the MEK, is a challenge to researchers. To prepare a polymeric membrane that can solve the problem integrally skinned polyaniline (PAni) membrane was cast on a woven polyester backing material, and then crosslinked in two different ways, chemically and thermally, to make the membrane resistant in MEK (methyl ethyl ketene) and toluene for long... 

Zeolite membranes are of interest due to their special properties; thermal and mechanical resistances and non-plasticization property in gas separations. Therefore, separation of H2S from natural gas by these membranes is the main goal of this thesis which is not investigated in the world. After some theoretical investigations including diffusion mechanisms of gases in the zeolites and adsorption mechanism of H2S on the zeolites, pure silica CHA-type (Si-CHA) zeolite was selected. After successful synthesis of Si-CHA zeolite, adsorption isotherms of H2S, CO2, and CH4 on the Si-CHA zeolite were measured over pressure range of 0-190 kPa and temperatures of 25 °C, 50 °C, and 75 °C. Acid gases... 

In the present work a comprehensive mathematical model has been developed for CFD simulation of transport phenomena in the hollow fiber membrane contactors. The system which has been studied was a gas sweetening including methane, carbon dioxide, and hydrogen sulfide in the gas phase and MEA aqueous solution as the solvent. Effects of temperature distribution on the contactor efficiency predicted taking into account the heat of solution, the heat of reaction, and the viscous dissipation. Major focus of the present study was on dynamic behavior of the contactor considering the entrance regions of momentum, energy, and mass transfers. CFD methods have been developed to solve the nonlinear... 

In this research incorporation of SAPO-34 zeolite filler into polycarbonate membrane was investigated for fabrication of mixed matrix membrane (MMM). The main purpose of addition of zeolite in polymer matrix is to enhance the separation properties of pure membrane by means of the selective pores of SAPO-34. SAPO-34 possesses pores with proper size for separation of CO2 from CH4 by molecular sieving mechanism. Pure polycarbonate membrane and PC/SAPO-34 MMM was prepared by solvent evaporation method using dichloromethane as solvent. Zeolite loading was varied between 5-30%wt. First of all, polycarbonate was characterized by DSC, FTIR and viscometer analysis in order to determine all the... 

The consumption of fossil fuels (oil, gas and coal) increased the concentration of greenhouse gases in the atmosphere that cause increase of earth atmosphere temperature and lots of environmental problems. Using appropriate alternative energy sources is one way to control this emission, while considering energy infrastructures shows this is a far solution. An early way for decreasing the emission of greenhouse gases in the atmosphere is injection of CO2 in geological formations. Since approximately 50 years ago some researches in this area have been developing. The most important limit of these projects is its costs so it is wise to combine them with gas injection projects in gas and oil... 

Low frequency (LF) O2 plasma was used to modify the surface of polysulfone (PSF) gas separation membranes. The effect of treatment time and plasma power input on the membranes was also investigated. Pure CO2 and CH4 gas permeation measurements were performed before and after plasma treatment. The results showed the increase of permeability of the treated membranes due to surface ablation and surface polarization. However, the CO2/CH4 permselectivity of the treated membranes varied from 7.7 to 45.3 depending on the treatment conditions. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy determined the introduction of oxygen containing polar groups on the surface... 

One of the most important environmental problem across the world is global warming due to increase in greenhouse gas concentration in atmosphere. The main objective of this thesis is to try to find some ways that lead to stop or decrease, increasing trend in greenhouse gas emission, espicialy CO2. The investigation of the sources of emission of CO2 and proposed methods to decrease the rate of the emission, reveals that sepration of CO¬2 from combustion products and its storage is the only promising solution of this problem. The common feature of all propsed methods for elimination of CO¬¬2 from combustion gas, is the presence of a separation step. The addition of this separation step to... 

In this study, we investigate the effect of adding potassium persulfate (PDS) (K2S2O8) and hydrogen peroxide (H2O2) to E.coli (as a model microorganism) photocatalytic removal system in the presence of the TiO2-P25 as photocatalyst and UV irradiation. In this regard, the PDS and H2O2 oxidants were added separately in the different levels of pH and photocatalyst loading under UV irradiation. The experimental points were determined based on the central composite design (CCD) and in order to study the main and the interactive effects of the photocatalyst concentration (mg/L), oxidant concentration (mg/L) and the pH on the final concentration of E.coli (cfu/mL), a response surface model (RSM)... 

Due to the environmental concern for the harmful effect of the release of HFCs on global warming there has been more interest for the use of hydrocarbons as refrigerants in recent years. In this project the performance of these refrigerants have been studied and compared with common refrigerants from the quantitative and qualitative point of view using a real-scale model of Peugeot-405 air conditioning system. Charging amount, inside temperature, cooling load, energy consumption of cycle, coefficient of performance and required time to steady state condition are the important comparative criteria for such a study. After carrying out a series of tests it has been considered that charge...