JOURNAL OF SEPARATION SCIENCE AND ENGINEERING
Year:2009 | Volume:1 | Issue:1|Papers Count:15

Pressure swing adsorption is an important unit for gas separation and purification. In order to develop the PSA technology, a pilot plant including four beds each with 1 meter length and 3.5 cm ID was designed and built. This pilot includes control systems and analysis systems to investigate the various operational conditions of beds carefully. In order to test this pilot, separation of oxygen from air, using zeolite 5A type adsorbents’, was studied. In this process the steps of feed pressurization, production, blow down, purge, pressure equalization (two steps) and product pressurization are included in a cycle. The effects of pressure, cycle time, flow rate of feed and purge on gas purity and recovery were studied. Also modeling and simulation of this process was done by orthogonal collocation method and MATLAB software. The numerical results obtained from modeling were compared to the experimental results and gave reasonable agreements.

In the present work, dispersed phase holdups have been measured in a Hanson mixer-settler extraction pilot plant with seven stages for two different liquid-liquid systems. The effects of agitation speed, dispersed and continuous phase flow rates have been investigated under a variety of operating conditions. Dispersed phase axial holdup profiles, determined by a sampling method, showed a strong nonuniformity. The results also showed that the dispersed phase holdup changes largely with the direction of mass transfer. Finally, an empirical correlation in terms of physical properties of liquid systems and operating variables was proposed to predict the holdup and good agreement between experimental data and calculated values of holdup was obtained.

Spinning Cone Column (SCC) is one of the distillation columns with applications in the food processing industries. Modeling and simulation of these columns are very complicated, due to the geometrical complexity, rotational parts, and different flow regimes inside SCC columns. Most of the published works on simulation of SCC columns were related to air/water systems; therefore application of these results to real flavor systems has challenges. In this study the mass transfer parameters including liquid film thickness, gas and liquid side mass transfer coefficients and HETP are reported for steam stripping of ethanol/water solution, the pilot scale SCC column has a diameter of 0.347 m with 30 cone sets and 1.2 m height. The average predicted gas and liquid-side mass transfer coefficients are 1.42 and 0.019 (S-1), respectively. Results show that gas and liquid side mass transfer coefficients are nearly constant over the operating ranges of gas and liquid flow rates, the predicted HETPs range from 0.072 to 0.246m. HETPs were increased by increasing gas rate, the predicted HETPs are in close agreement with the data reported in literature.

In the present study, templated and non-templated asymmetric silica membranes were prepared successfully by sol-gel polymerization route using cationic surfactants (CPB) as template agent. Silica membranes were characterized using N2 adsorption and SEM techniques. SEM results showed that after four times coating process a thin film of silica with a thickness of 2mm was deposited on support surface. BET and BJH methods using nitrogen physisorption data, revealed that the surface area of the membrane was increased significantly when a surfactant was used as template also the average pore size of the silica membrane was increased when the template was added. The prepared silica membranes were used in single gas permeation and mixed gas separation experiments. Permselectivities of H2/CH4 (149) and H2/CO2 (15.5) were obtained for free template membrane and 135 and 35, respectively for templated membrane at 400oC. Separation factors for H2/CH4 and H2/CO2 obtained from the mixed-gas separation experiments with 50/50 (vol%) gas mixtures were 131 and 12.9 for non-templated and 123 and 28.4 for template silica membranes, respectively.

Solvent extraction of gallium from Jajam Bayer process liquor was carried out using Kelex100. Organic phase including Kelex100 as an extractant, isodecanol and kerosene were used. In this research, Kelex100 and isodecanol concentrations in organic phase (%v), aqueous to organic phase ratio, time and temperature were optimized using Taguchi experimental design method (L25 (55)). Optimized conditions were determined as: T=40oC, Time=60 min, A/O ratio=1:1, Kelex100=12% (%v) and isodecanol=5% (%v). Under these conditions gallium extraction was 92%.

In recent years, bacterial leaching of copper from low grade chalcopyritic ores has been adverted very much. Different parameters such as the type of microorganisms, pH, temperature have a direct or indirect influence on the bioleaching efficiency of sulfide minerals. Therefore, the main objective of this study was to quantify the potential of thermophile microorganisms for copper recovery from low-grade chalcopyritic ores. Using a representative chalcopyritic low grade copper ore from National Iranian Copper Company with a total copper grade of about 0.344% (CuFeS2= 0.78%), and two different thermophile bacteria, several bioleaching tests were conducted. The final results of lab -tests show the potential of extremely thermophiles for bioleaching of copper from this type of low grade ores is higher than moderate thermophiles. At optimum temperature, pH and Fe2+/ Fe3+ ratio, the average copper recovery from low grade ore with extremely them10philes is up to 17% higher than that with moderate thermopiles.

Combustion of sulfur containing fuels will lead to formation of air pollutants such as SO2 and acid rains. It is not possible to desulfurize all the sulfur-containing compounds of the fuels by the existing sulfur removal methods (such as hydrodesulfurization). Therefore, many researchers have focused on biological sulfur removal. Varios parameters have a great role in isolating biodesulfurizing microorganisms, which are explained in this paper. These papmeters have been considered and as the result, three biodesulfurizing microorganisms have been isolated: BS1 thermophilic bacterium, MS1-1 mesophilic bacterium and WS4 fungus (Stachybotlys sp.). They are able to desulfurize the heavy crude oil of Soroush oil field with 82% (in 6 days), 76% (in 6 days) and 76% (in 3 days), respectively. They are able to remove sulfur and nitrogen from the heavy crude oil, selectively. Heavy crude oil biodesulfurization project was initiated by Petroleum Engineering Development Company (PEDEC), a subsidiary of National Iranian Oil Company.

Membrane separation systems as capable tools selectively separating a specific component have attracted the affeation of many researchers. This method of separation has application in different engineering aspects such as chemical engineering. In the present paper, the application of membrane systems for the separation of iodine, chromium and gold ions which have environmental importance and for the separation of carbon dioxide and olefin paraffin mixtures that have industrial importance has been reviewed.