Nashrieh Shimi va Mohandesi Shimi Iran
Year:2014 | Volume:33 | Issue:3|Papers Count:11

ABSTRACT: In this work an annular continuous-flow photoreactor with a UV-C lamp (lmax=254 nm) in the center of photoreactor has been used in the removal of p-nitrophenol by UV/S2O82-process. For the first time a kinetic model has been proposed for UV/S2O82- process. The rate constant of the interaction of SO4-· radicals with the p-nitrophenol molecules has been estimated through the adoption of kinetics model (1.1 ×105 M-1s-1). This model allows predicting the concentration of p-nitrophenol in different photoreactor lengths for different flow rates and initial concentrations of oxidant.

Due to decline in oil production, inefficiency of conventional EOR methods and a huge trapped volume of oil in reservoirs, it is reasonable to use helpful methods with higher initial cost. Adsorption phenomenon that has been affected by several factors, weakens the success of SAG injection which its efficiency is confirmed by fractional flow analysis. In this study, by conducting static and dynamic adsorption experiments, the effects of sacrificial agent, gas phase, and surfactant concentration on adsorption density were examined. Next, SAG experiments were performed in order to compare with the conventional methods such as water alternative gas injection and continious gas injection. Also, the effect of sacrificial agent on oil recovery was studied. Spectrophotometric method based on the formation of an ion-pair between Safranin o and surfactant was used in all experiments for determination of surfactant concentration. The results of adsorption experiments show that SDS adsorption density was reduced when nitrogen was imposed instead of using methane. Also, the amount of surfactant loss was decreased in precense sacrificial agent. Static experiment shows that the amount of loss of surfactant on dolomite and shale were higher than Silica. Flooding experiment results show that SAG injection increase final recovery up to 10% and 28% in comparison with WAG and continous gas injection, respectively. formation of stable foam in optimum injection rate leads to decrease in gas mobility. Using CLS slightly increases the ultimate oil recovery up to 2 %, while it decreases the loss of SDS 22 percent.

Sorbitan fatty acid esters called sorbitan esters, are surfactants widely used as food in the production process as emulsifiers. Sorbitan esters are well known emulsifiers suitable for use in food, pharmaceutical products as well as many other applications. One such technique involves direct esterification of sorbitol or an intramolecular condensate of sorbitol with fatty acids in the presence of acid or alkali catalysts in one step process. In two step process, sorbitol is first dehydrated to sorbitan and then esterified with acid or alkaline catalysis. In this study two steps process due to better compatibility was selected. For the first and second steps, catalysts were tested fur phosphoric acid recognized as suitable catalyst for this reaction, effect of temperature and pressure and catalyst concentration were determined. The results show that dehydration rate is proportional to temperature and catalyst concentration but pressure has negative effect. For the second step, alkaline catalyst was studied and sterification was affected under alkaline condition. Surface tension was studied by different amount of sorbitan ester. Produced sorbitan ester reduced surface tensionwith CMC 15mg/L and saponification number of 147.

This research was conducted to study and determine the negative effect of metal ions on whiteness of the chemimechanical pulp samples which are produced in Mazandaran Wood and Paper Mill. The chemimechanical pulp samples were prepared from the mill in unbleached from. EDTA chelating agent was used with concentrations of 0, 0.25, 0.5, 0.75 and 1% in order to neutralize the metal ions which cause further aging and yellowing of the CMP samples. Then, each sample was wetted with solutions containing metal elements of Fe2+, Fe3+, Cu2+, Al3+ and Mn2+ after drying. The obtained results revealed that the maximum effect in whiteness reduction belongs to the Fe2+ ion while the minimum effect is related to Al3+ ion. Moreover, it can be inferred from the results that wetting of the samples at different concentrations of the chelating agent (EDTA) has an optimal value in improvement of the whiteness characteristics of the paper. More than this optimal value, further increasing the EDTA concentration does not improve whiteness and brightness durability of the samples. Whiteness of the CMP degrades significantly by increasing the aging time.

Biodegradable composites are prepared by mixing of benzylated rice husk, poly styrene and e-caprolactone. At the first step of this investigation, rice husk as a cheap and natural material was modified with benzylation reaction and samples was studied by FT-IR spectra. A good reaction between benzyl groups of benzyl chloride and hydroxyl groups of rice husk is observed from FT-IR spectra. The ThermoGravimetery Analysis (TGA) showed that the benzylated rice husk has a more thermal stability than rice husk. At the next step, benzylated rice husk with different percentages added to polystyrene and polycaprolactonein chloroform, and the polymeric films were prepared with solvent evaporation. Mechanical properties of these films were measured by the tensile test. The mechanical properties of samples were improved by addition of 10-40 percent of benzylated rice husk.

Corrosion means the destruction or the deterioration of materials because of reaction with its environment. One of important effective factors on corrosion rate is fluid motion in pipe and all of construction that have flow of fluid. This study was carried out to investigate the effect of fluid flow on the corrosion of simple carbon steel ST37 (AISI 1020) in aqueous solution of Bandar Abbas’s gas well at 25oC under the air-saturated condition. To investigate the mechanism and kinetic of corrosion in different hydrodynamic conditions, a Rotating Disk Electrode (RDE) was used. The imposed potential and polarization on the metal sample, a potentiostat system was utilized and to interpret the data, Linear Polarization Resistance (LPR) and tafel polarization methods were applied. To study the effect of fluid flow on the rate of corrosion, the speed of rotating disk was changed from 100 to 1700 rpm. Drawing the related polarization curves mass transfer coefficients were predicted. Using these coefficients and empirical correlation between dimensionless groups as Sh= 0.8433 Re0.497Sc1/3 was found. This correlation is much closer to the correlation proposed by Levich. Experimental data also shows that increasing the disk speed to 1000 rpm. The rate of corrosion (due to the increases in mass transfer rate) was increased. Above this speeds the rate of corrosion in independent of disk speed. Finally to study the corrosion inside the pipes using the analogy aspects, a relation to predict the disk speed (generating the same velocity of fluid inside the pipe) was obtained.

Solar energy is a renewable and crucial form of energy for many natural processes on the Earth. The application of solar energy to provide hot water, heating and cooling of residential area has been considered in Iran in recent decades. In this paper, simulation and techno-economic investigation of a single-effect water-lithium bromide solar absorption chiller in Isfahan climate is presented. A single effect absorption chiller with a capacity of 19 kW (5 tons of refrigeration), providing cooling for a 200 m2 residential area is proposed. Maximum energy required for cooling such a building is 17 kW, which occurs in July. The daily occupancy schedule is considered between 7a.m. and 7p.m. and the cooling schedule is considered between May 1st to September 30th. At low solar radiation, the system operates with the energy stored in the storage tank and with an auxiliary heater. Economic results show that the evacuated tube collector with total absorber area of 30m2 is the best option in this plant. This system in comparison to a similar capacity direct-fired absorption chiller will save 895 m3 of natural gas per year.

Development of innovative thermodynamic cycles is important for the efficient utilization of low-temperature heat sources such as solar, geothermal, and waste heat sources. Binary mixtures exhibit variable boiling temperatures during the boiling process, which leads to a good thermal match between the heating fluid and working fluid for efficient heat source utilization. This study presents a theoretical analysis of a combined power cycle, which combines the organic Rankine cycle and parabolic through collectors cycle, uses different organic fluid as the working fluid and produces power. This cycle, also known as the ORC, can be used as a downstream cycle using heat source from a solar radiations, and it can using low to mid-temperature sources with concentrator or not. A thermodynamic analysis of power was presented. The performance of the cycle for a range of turbine pressure, ambient temperature, condenser pressure, altitude, and different working fluids were studied to find out the sensitivities of gross power, net power, electrical efficiency, net electrical efficiencies and plant auxiliary, effective efficiency. The thermodynamic analysis covered a broad of boiler temperatures, 250oC and pressure 20 Bar. The first law efficiencies of 11.85 % are achievable at 250oC and pressure 20 Bar with R-123 as working fluid. The cycle can reached to 19.64 % net electrical efficiency with recuperate heat exchanger that works at 44 bar pressure 250oC temperature and with R-141B as working fluid.

Increasing of greenhouse gas emissions is one of the major concerns in the international community. 50 percent of increment of carbon dioxide concentration, which is forming the most of greenhouse gas, was occurred during the last fifty years. Because of impermeable caprock, hydrocarbon reservoirs are appropriate option to sequester carbon dioxide. On the other hand, due to high amount of fuel consumption in the world, implementing carbon dioxide Enhance Oil Recovery (CO2 EOR) to improve oil recovery is logical. So, to achieve these aims, using efficient method to improve the volumes of produced oil and stored carbon dioxide is mandatory. Up to now, due to lack of proper method, single objective optimization method was conducted. Nowadays, using multi objective optimization methods such as non-dominated sorting genetic algorithm leads to select appropriate scenario during encountering upcoming situations. In this study, non-dominated sorting genetic algorithm was applied to an oil reservoir and some appropriate scenarios with regard to maximization of produced oil volume and stored carbon dioxide volume were introduced. The main advantage of this methodology is selection of proper scenario with regard to economic variations after implementing optimization process.

Claus process is a well-known industrial method to recover elemental sulfur from hydrogen sulfide in Sulfur Recovery Units (SRUs). Despite high efficiency of such units, these SRUs operate at much lower efficiencies than the standard value of 97% due to some operational shortcomings. Presence of heavy aromatic compounds such as Benzene, Toluene, and Xylene (BTX) within the acid gas feed entering the SRUs, can harmfully affect Claus catalyst performance and decrease the overall efficiency. In this research, Promax simulator was employed to simulate SRUs of Khangiran natural gas refinery. Five different scenarios were discussed to increase the temperature of combustion chamber and BTX destruction as well. Finally, the effect of BTX content entering the catalytic beds was investigated on the efficiency of catalytic beds and the overall sulfur recovery.