مجله فرآیند نو
پیاپی 62 (تابستان 1397)

Combustion of crude oil products such as gasoline and gasoil cause serious and extensive environmental pollution. One of the main objectives in refineries is to eliminate sulfur or to convert sulfur compounds to harmless materials and strict restrictions have been introduced on the reduction of emission of pollutants such as sulfur oxide. Nowadays, various methods of sulfur reduction processes are being used in petroleum cuts: hydrodesulfurization (HDS); adsorption desulfurization (ADS); biodesulfurization (BDS); oxidative desulfurization (ODS). Among the mentioned methods, researchers have shown a great interest in oxidative desulfurization (ODS) method because of simplicity of the process, no need of hydrogen, moderate operational condition and less capital and operational cost. In this article a thorough and comparative investigation has been made on using different catalysts and ionic liquids on the performance of oxidation process and percentage rate of desulfurization in various operating conditions.

Computational Fluid Dynamics (CFD) is a good numerical tools to solve complicated equations like fluid flows, heat transfer and chemical reactions such as flares issue. In this study, the effect of a changes in the flow rate on flare performance of one of Iran's oil refineries in actual mass flowrate range of 4,000 pounds per hour was calculated using CFD modeling, with Ansys Fluent software 16.0. Also its geometry and mesh designing were carried out by Gambit software 2.4.6. To investigate the effect of changes in flow rate on the flame temperature, flame length, profile of the concentration of combustion species and the turbulent stream pattern in the flame The related calculations are 2D in terms of axis symmetry in which the turbulence was modeled by standard k-ε, Non Premixed Combustion models, Simple Algorithm based on basic pressure and steady state condition were applied and also neglected the effects of the wind. By aid of independant variables from mesh, for actual mass flow ranges, we chose 68700 cells. The simulation results showed that although by changing the mass flow rate, in the range of 4000 pounds per hour does not change the maximum flame temperature. But changes the altitude that happens in this temperature. The length of flame varied in following situation, real mass flow was 14.9 meter which by %10 changes in mass flow, the length displaced 0.66 meter. Therefore, the rate of k (turbulence kinetic energy), ε (loss kinetic energy) increased by increasing the mass flow rate. The distribution of hydrogen and methane constituents in the range of the flame is equal to 1% molar and, with increasing massflow rate both distribution widespread and range of distribution of water and carbon dioxide is 5 and 10%, respectively both Concentrations increased by increasing the mass flow rate.

This study was aimed at increasing the cetane number of the blends of diesel-biodiesel fuels adding a hybrid cerium dioxide-based on carbon nano tubes catalyst. For this purpose, cerium dioxide as a catalyst and multi-walled carbon nanotubes (MWCNTs) as the support catalyst at three concentrations (30, 60 and 90 ppm) in diesel-biodiesel fuels containing diesel, biodiesel (B100), 5% biodiesel blend (B5) and 20% biodiesel blend (B20) was investigated. The results obtained revealed that the synthesized nano catalyst with a functionalized carbon support and due to flexible distribution and good stability resulted in significant increases in the cetane number. Also, the test results showed that by increasing the concentration of catalyst in fuel types, the cetane number shows a greater increase. So that the greatest increase of cetane number in concentration of 90ppm for diesel, biodiesel, B5 and B20 were reported by up to 1.02%, 3.83%, 1.19% and 3.2%, respectively.

There are a lot of concerns about minimizing the amount of industrial wastewater. Extraction and recovery of heavy metals from wastewater is more attractive than methods such as precipitation. Many researches had investigated the elimination of heavy metal ions from wastewater. Emulsion liquid membrane is one of the separation methods with high selectivity at low contaminant concentration. In this paper, application of emulsion liquid membrane for remove copper from waste water with concentration of 100 ppm is investigated. The effect of some parameters such as surfactant concentration and stirring speed and contact time on the separation performance are studied. The obtained optimum conditions are 0.6 mM for concentration of surfactant, 5 min the contact time and 300 rpm for stirring speed. This study can be useful for future new applications and innovations in the case of emulsion liquid membrane in many different industries such as petroleum and oil refinery.

Dwindling of conventional oil reserves and increasing global demands have caused increased exploitation of heavy crudes accounting for a large fraction of the world's crude oil resources. Formation of stable water-in-crude oil emulsions in hydrocarbon reservoirs or in production processes are inevitable increasing environmental problems as well as costs of transportation and refining. Heavy crude oil viscosity also makes several problems during extraction and transportation. Viscosity reduction processes of heavy crude oil for pipeline transportation have been subject of many researches. In this paper, challenges involved in use of these energy resources have been evaluated using a comprehensive literature review.

In this study, tide flow pattern and sediment transportation in Mahshahr firth canal was evaluated by MIKE21 software and was validated by Imam Khomeini seaport station data. Then based on flow patterns results, sediment model has been tried. According to periodic hydrographic data in ArcGIS software, the seabed level variation was also evaluated. Seabed thickness changes in the middle of sector are more due to extra changes in flow velocity pattern in tidal time at this zone. In all of these sectors, suspension sediment density rate is high. Mean rate of accumulative sediment aggregation is about 13500 m3 per year.