Nashrieh Shimi va Mohandesi Shimi Iran
Year:2008 | Volume:27 | Issue:2|Papers Count:13

Sodium chlorate is one of the most important chemical components which is produced via electrolysis process. Electrical power consumption and economic of the process are directly related to the design of electrolysis cell, material of construction and structure of the electrodes. In this research the optimum conditions for the production of sodium chlorate in a lab scale electrolysis cell incorporating DSA electrodes was investigated. Experiments were conducted in order to elucidate the effect of process variables including current density, temperature, and time, on the voltage of the cell and the amount of the product. The feed was 1000 mL aqueous solution containing 300 g/L NaCl, as its initial concentration, and the anode was one of DSA with an effective surface area of 10 cm2. The Taguchi method was used to design the strategy of the experiments. The results revealed that at the operating conditions of T=85°C, pH=6.8-7, I=4 A, and an operation duration of 2.5 hr, an amount of 163.86 grams of ClO3- was produced while the energy consumption was equal to 7221.84 kWhr/ton ClO3-. Meanwhile, the voltage of the cell was 3.3 V which was increased about 0.2-0.3 V during the 2.5 hr of operation.  

Petroleum asphaltene is the heaviest portion of oil fractions. Asphaltenes are defined as materials insoluble in aliphatic hydrocarbon solvents (n-pentane or n-heptane) and can cause coking or plugging difficulties in refineries and transportation lines. Therefore the structural characteristics and aromaticity of asphaltenes are important to refiners for determining the operating parameters of the process units for deep conversion processes structural characterization studies have been carried out on asphaltenes extracted from three Iranian crude oils. The aromaticity and crystallite parameters as well as the layer distance between aromatic sheets, the distance between the saturated portions,the average diameter of aromatic sheets and the number of aromatic sheets in a stacked cluster of each sample have been estimated from X-ray diffraction. Relation between the asphaltenes aromaticity parameter and hydrocarbon distribution GC-mass chromatogram of crude oils has been investigated. Increasing in aromaticity parameter is proportional to the large molecular size of hydrocarbons content.

Nowadays, gel polymers are widely used in order to prevent production of unwanted water. In this research an experimental study was performed to investigate the efficiency of gel polymers to reduce the production of unwanted water. Different gel polymer compositions and the effect of different parameters (temperature, pressure, pH and salinity percent) were individually investigated. Optimized gels were investigated on multi physical models for Ahwaz-Asemary reservoir conditions. Based on the obtained results, increases in temperature and salinity reduced the gelation time, while pressure was not an important parameter. The results obtained from the physicals model indicate that there is a 40 to 60 percent reduction in water cut under reservoir conditions.

Produced Water Re-Injection (PWRI) has earned much interest among the other methods of disposal of the produced water from the reservoirs. It is both environmentally friendly and economically which can also be seen as one of the EOR methods to maintain the reservoir pressure. However, the presence of contaminants like the colloidal particles in the produced water is led to the decrease in the permeability of the reservoir, a phenomenon which is usually referred to as formation damage. The process of formation damage is as same as cross flow filtration. In this paper we do modeling of formation external cake in cross flow filtration for oil reservoir in steady state condition and we find cake thickness, permeate velocity, cross flow velocity, concentration and pressure profile vs. reservoir height and finally we do sensitivity analysis of cake thickness vs. different parameter of model.

Sodium monofluorophosphate Na2PO3F (SFP) as a bactercides and a fungicides is used in toothpastes. There are several methods for production of SFP, but in general, the yield is low. In this paper, the reaction of various phosphates and polyphosphates with sodium fluoride was researched. The results show that SFP with appropriate purity is prepared by reaction of 1P, 2P, 3P with sodium fluoride. When P2O5 is added, purity is increased. SFP with suitable purity and yield is prepared by reaction of long- chain (n³12) and ring phosphates with NaF. High temperature and long time is caused to product pyrophosphate because of decomposing of SFP. The results distinguish the most oppropriate yield (» % 100) and purity (over % 95) for preparation of SFP in temperature limitation 600-800°C and heating time<15 minute. The most oppropriate temperature Condition is 600°C for long-chain phosphates and 660°C for 3M, 4M with NaF and 2P, 3P when P2O5 is added. The analysis was done by standard method of USP reference.

In this research the influences of horizontal 90° and 180° bends on the two phase pressure loss and flow pattern for air-water mixtures inside a 2.4 cm smooth pipe are investigated. Based on experimental pressure loss data in bends a prediction model is proposed. Comparison of new model with previous models in the literature shows that this model provides a better estimate of pressure loss in bends. Several experiments are also accomplished to observe flow pattern in presence of bends. In region of flow, the flow pattern in the recovery region is temporarily turned into annular flow. Based on the present visualization, two flow pattern maps are proposed to describe the effect of bends on transition of flow pattern.

Due to growing interest in using TiO2 and reducing its primary resources, many researches have been carried out to recover TiO2 from industrial slimes. Red mud is obtained during alumina production from Bauxite by bayer process. It contains considerable amount of TiO2. The nature of compounds in red mud is complex, therefore hydrometallurgical processes have been found more efficient for the recovery of TiO2. In order to recover TiO2 from red mud, several work have been done in laboratory and pilot scale using hydrometallurgical and combination of hydro-pyrometallurgical processes. In this research, characterization of red mud and its applications were studied followed by considering recovery methods for the production of TiO2 from red mud. Also, in this research identification of red mud that generated during alumina production in Jajarm were studied.

Stocumetry, crystallity and morphology’s influence on electrochemical properties on active material reacted to syntheses method completely. Spinal lithium manganese oxide having the formula LiXMn2O4 (X=0.3, 0.4 and 0.5) was synthesized in the form of thin film on a graphite substrate by electrochemical method using manganese sulfate and lithium hydroxide as starting material. The lithium and manganese concentrations in the resulting materials were analyzed using an inductively coupled plasma spectrometer (ICP). X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the structures of the electrodes. Electrochemical behavior of active material syntheses was examined by charager/discharge test with LiMn2O4 as cathode electrode, lithium as anode electrode and A solution of 1 M lithium perchlorate (LiClO4) in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) at a ratio of 1:1 as the electrolyte by constant current of 0.1 mA/cm2, for the range of 2.5 to 4.3 V at room temperature. Furthermore, electrochemical characterization of the prepared active material were analyzed using cyclic voltammetry (CV) in the voltage range 3.5-4.6 V with rate 0.15 mV/s in electrolyte mentioned above. Result show optimum time for heating option is 20 minute and material with stocumetry ratio X=0.5 having better behavior than other ratios.

COMSIM has been developed in Excel spreadsheet to simulate industrial grinding circuits that consist of ball mills and hydrocyclone. In this software Population Balance Model (PBM) has been used for simulating ball mill performance. In this model, the required parameters are mean Retention Time Distribution (RTD) of particles inside the ball mill, selection function and breakage function. Also, for simulating hydrocyclone performance two empirical models, Plitt and Nageswararao models have been used. These two models predict performance based on hydrocyclone geometry and inlet pulp characterisation.This package allows simulation of circuits consist any layout configuration of ball mills and hydrocyclones. Data obtained from the simulator are compared with measured data from the plant. This reliable performance of the simulation software. Easy handling of input and output, validation of input data, multiple displays of various flows and graphical representation of the results constitute the characteristics of this user friendly similuator.

Mixing the wastewater of Industries with natural water has caused environmental pollution. So researcher tries to obtain methods and optimum conditions for wastewater treatment. One of Important stage in wastewater treatment is dissolved air flotation. DAF is used for the removal of suspended solids and oils from wastewater. In this paper, the effect of several parameters on flotation efficiency with Cationic Polyacrylamide as flocculants, was examined, namely, (a) concentration of cationic flocculants, (b) pH (c) fast mixing time, (d) fast mixing speed, (e) slow mixing time, (f) retention time and temperature. After dwesign of experiment, in each trial turbidity of wastewater was measured by spectrophotometer. Results show that contribution of pH and concentration of flocculants on flotation efficiency are 75 % and 9 % respectively. Cationic polyacrylamide led to a significant increase in the settling speed and effect of temperature is negligible. In the optimum condition, the outcome of the DAF unit is increased and amount of suspended solid and oil in wastewater is decreased effectively.