Year:2004 | Volume:37 | Issue:4 (82)|Papers Count:13

Nickel Catalyst is used in hydrogenation process of triply cerides in Liquid cooking oils such as soybean, palm, peanut, canola and sunflower. The hydrogenation process has three phase, oil, hydrogen gas and solid Nickel Catalyst Particles. Hydrogenation is widely nude to alter properties of oils namely oxidative stability and melting characteristics. After some time Catalyst deactivates by poisons in oil and hydrogen gas, and required reclamation of Nickel from spent Nickel Catalyst. As an important step to regenerate the Catalyst, the gas frication process is needed to eliminate carbon black residues remaining on the surface of the Catalyst. In this research the spent Catalyst was decarburized using air by twos methods.A number of experiments were carried to show that 45 weight percent of deactivated Catalyst contained Carbon black, remaining oil and some by products of deactivation process. Also, A series of batch experiments were commented to determine the optimum Combustion temperature of 450oC. It was observed that in this method the remaining oil in Catalyst was combusted and produced a lot of smokes.In another method, a lot of experiments were used to solve, the remaining oil in the catalyst using carbon Tetrachloride solvent. After drying these samples, the gasification process was followed up. As a result, it was shown that in this method 23 weight percent of catalyst contained oil and 22 weight of percent the deactivated catalyst contained coke and other by products.

In this study, bulk LaCoO3 was prepared by the citrate method, and supported ones by impregnating silica and alumina with a solution of cobalt and lanthanum nitrates. Different promoters of ceria, zirconia and lanthana were used to inhibit the interaction of the perovskite and the support. The performance of the catalysts was examined from 100 to 750 oC in presence of a simulated automobile exhaust gas. The bulk LaCoO3 converts CO at temperatures less than 300 oC, while it converts C2H6 at about 700 oC. The complete conversion of both CO and C2H6 occurs at temperatures higher than 700 oC on supported catalysts. The XRD spectra of the catalysts show that there is a strong interaction of the perovskite and the support. Ceria as one of the promoters used, shows the best results for reduction of the interactions.

In conventional reservoir simulators, relative permeability curves are usually corrected for different values of surface tension using Coats correlation. Based on a research work in Heriot-Watt University, it was concluded that high rates near well bore in condensate reservoirs cause the enhancement of relative permeability of condensates and gas. It was also suggested to consider capillary number instead of surface tension for correction of relative permeability curves. Also, in condensate reservoirs, in contrary to dry gas reservoir, the negative effect of inertia (defined as skin factor) is not constant but it is a function of rate.In order to study the above phenomenon in a reservoir scale, a fractured condensate reservoir in Nar field was selected. The modeling of reservoir fluid was first constructed using an equation of state and then, relative permeability curves were obtained and corrected for surface tension only. By the reservoir simulation using Eclipse-100, we were able to obtain a good match between pressure drop versus rate in simulation and a pressure-flow test in one of the wells. Using In conventional reservoir simulators, relative permeability curves are usually corrected for different values of surface tension using Coats correlation. Based on a research work in Heriot-Watt University, it was concluded that high rates near well bore in condensate reservoirs cause the enhancement of relative permeability of condensates and gas. It was also suggested to consider capillary number instead of surface tension for correction of relative permeability curves. Also, in condensate reservoirs, in contrary to dry gas reservoir, the negative effect of inertia (defined as skin factor) is not constant but it is a function of rate.In order to study the above phenomenon in a reservoir scale, a fractured condensate reservoir in Nar field was selected. The modeling of reservoir fluid was first constructed using an equation of state and then, relative permeability curves were obtained and corrected for surface tension only. By the reservoir simulation using Eclipse-100, we were able to obtain a good match between pressure drop versus rate in simulation and a pressure-flow test in one of the wells. Using

Steady-state heat transfer in agitated multi-phase gas-liquid-solid cylindrical vessel has been investigated. The vessel was a flat bottom type equipped with four Non-standard symmetrical baffles. The conventional jacket was used for cooling the mixture in the vessel. An up pumping 45 four blade pitched turbine was used for efficient agitation. Three materials, sand, water and air are used as solid, liquid and gas phases, respectively. Air was introduced through a ring sparger located below the impeller. Agitation speed of 800, 1000 and 1400 rpm were used. Linking the multiphase hydrodynamics to the heat transfer is essential to properly understand the heat transfer process in solid containing stirred vessels. In this study the mean size of particles were varied from 0.1 to 0.4 mm and the solid loading was used with variation of weight percentages of 2.14 to 10.3. The effect of rate of gas on the rate of heat transfer was investigated by variation of flow number (Qg /Nd3) from 0.008 to 0.02. A correlation is derived relating the heat transfer coefficient to the operating variables through dimensionless numbers.

In the present investigation, the sensitivity of a SnO2-based sensor in the presence of simulated automotive exhaust gases at different temperatures is investigated. The simulated gas is CO and/or ethane mixed with different amounts of air, to provide the corresponding automotive exhaust gases with different air-to fuel ratios at inlet to the engine. The sensor response is investigated at temperatures ranging from 300-400 oC for CO and 400-460 oC for ethane. As the air-to-fuel (CO and/or C2H6) weight ratio is varied, the resistance of the sensor shows an S-shape response: a low value for the sensor resistance at low air-to-fuel (ATF) ratios, a transition region, and a high value at high ATF ratios. The changes in the transition region, depending on the temperature and reducing gas, is as high as one to three orders of magnitude. For CO, the transition region occurs at ATF ratios lower than the stoichiometric value, while for C2H6 it occurs at values higher than that of stoichiometric. When the simulated gas passes through a catalytic burning chamber upstream of the sensor, a sharp transition in the sensor resistance occurs right at the stoichiometric ATF ratio. Therefore, the sensor can be

The high annual rate of production of rice in our country usually resulted in accumulation of a large quantities of bran. This fact prompted us to evaluate different utilization of the rice bran. For this purpose, crude rice bran oil extracted from bran with commercial n- hexane by automatic sox let extractor and desolventized by rotary vacuum evaporator. Then crude rice bran oil was dew axed by chilling to 18 C followed by centrifuging . The wax sludge obtained was 66% free fatty acids and 34% waxes, whereas the oil phase was 64.5% fatty acids and 35.5% glycosides. The dew axed oil was evaluated as an antifoaming agent for aqueous media and compared to commercial oleic acid. Based on our results and findings, the dew axed rice bran oil has an antifoaming power equal or greater than oleic acid.

Today, the evaluation of hydrocarbon generation by using the ∆log R method as a practical method has been successfully applied to many wells worldwide.‏This method has been presented for prediction of organic richness of source rocks by Passey et al., in 1990 and can be accurate over a wide range of maturities. It is based on the overlaying of a properly scaled porosity log (generally the sonic transit time log) on a resistivity log, determination of separation between the logs, estimation of total organic carbon (TOC) and S2 (quantity of free hydrocarbon released during pyrolysis in Rock-Eval instrument). The organic richness of formations without sampling could be accurately evaluated by using this method.In this paper, the organic richness of Kashafroud formation has been evaluated by using the ∆log R method in wells 16 and 30 of Khangiran anticline (Kopet-Dagh region) and it has been compared to core samples.

Drilling and blasting operation is performed simultaneously with mechanical and electrical jobs in phase one of the development project of Masjed Solaiman Dam power plant. To avoid any damage to structures and facilities, precise estimation of land vibration is required. This would help a proper design for blasting operation, too, due to which the level of ground vibration must remain within the permitted limits set up by some well-accepted standards. In this investigation, based on maximum instantaneous charge and the distance from blast locations, vibration is estimated by means of both empirical models and neural network technique. The analysis of recorded data revealed that application of five empirical models resulted in more or less similar results whereas the neural network method showed to be much more accurate technique. Due to non-linearity, flexibility and the ability of accepting variation in the number of impacting factors, the neural network method was observed to be, by far, more capable technique. It is, therefore, concluded that the latter method can be considered as a proper tool for ground vibration estimation.

Pyrrhotite is the most important gangue in nickel sulfate mines. Its presence not only produces distractions in upgrading circuits applying flotation but in smelter too by causing SO2 emissions and thus environmental pollution. In this article micro flotation of pyrrhotite was studied using two pure synthetic samples applying a modified Halimond tube. Also to evaluate the effect of impurities a natural sample from Sudbury region in Canada was tested. Results show the different behavior among samples while flotation parameters such as pH, concentration of sodium cyanide, presence of copper ions in pulp and oxidation vary. Based on the results, although applying an alkaline environment, intensive oxidation of the mineral samples and using sodium cyanide as depressant for pyrrhotite are presenting acceptable results to eliminate the mineral in flotation stage; however, the degree of response is a function of crystallography and impurities. Pyrrhotite flotation in alkaline pH, while using 20 mg/l collector, resulted in a recovery between 20 and 30% depending on type of the sample. Applying oxidation at the same pH lessons the recovery for about 10% in all cases. In the other hand, sodium cyanide is able to reduce the recovery for about 5% for all samples. Activating pyrrhotite samples by copper sulfate resulted in a similar behavior in all three types of pyrrhotite.

Several models have been purposed to determine carrying rate and kinetic constant in flotation columns. Each of these models is credible under special circumstances. This is truer regarding empirical models. Another problem in respect to these models is that they produce different results compare to the outcome of the test works. Therefore, it is of a crucial importance to determine above mentioned parameters based on the observations in order to have an accurate scale up for flotation columns. This procedure has been followed for Sarcheshmeh Temporary Molybdenite cleaning plant. The test results were different from those obtained using empirical formula. Several reasons have been offered to explain this contradiction.

Horizontal and vertical distribution of stress, in different layers of unbound materials of pavements, as well as stress in contact points between rock particles of these layers have been studied. Ring Chamber was used to study horizontal and vertical stresses under static vertical load. Stresses in contact points were measured using pressure films, placed in Ring Chamber. To investigate the influence of grain size on stress distribution, five size ranges of aggregates were tested. Analyses of the tested pressure films show very high stresses developed in some contact points due to the applied load. Variation in grain size of samples influences the stress distribution and that fine aggregates distribute stress more evenly than coarse aggregates. It has also been found that coarse aggregates have more roles in stress distribution and higher stresses developed in contact points between coarser aggregates.

Iron oxide is an important impurity in micron zed silica powder which has an adverse effect on quality of the product. Not only it causes different colors in the glass but it brings out some difficulties in glass production line as well. In this article, silica used by Takes tan Glass Company, a major producer of glass in the country is upgraded by acid leach and magnetic separation techniques. A sample feed with 0.082% iron oxide was used in mineralogical studies. This sample was then concentrated under different conditions. Variables such as percentages of solid content in the pulp, acid leach conditioning time, temperature, type of acid used and its dosage, and magnetic field intensity were optimized. At last, the combination of acid leach and magnetic separation methods was studied and results showed that a silica upgrade with 0.018% iron oxide can be achieved.