Year:2009 | Volume:42 | Issue:8 (118)|Papers Count:9

Gas refineries are usually located in remote and non residential areas. For that it takes quite a while to reach to the end users. Moreover, in the peak seasons such as winter, the consumption rate is normally very high. Such circumstances make the supply management to be very complex, particularly for the large and populated cities like Tehran. In order to take a reliable control on the demand and to know how the extraction and/or the production rate can match the consumption rate at different regional places especially those of the rural areas, one should think of an off-side un-classical method. Among these, the Artificial Neural Network, ANN; is one of the most common methods which are currently used for different functional goals. In this research an investigation is carried out for applying ANN method for in-advance forecasting of gas demand load. The method is based on weather parameters with multilayer back propagation, BP algorithm. Throughout the current work, the effective daily temperature is determined, after which the data of the last days is used for network training. Finally it is shown that up to nearly 93% & 99% of the result is in a good agreement with the real data for daily and monthly gas load forecasting, respectively. The method however can further be developed for prediction of other necessary information in any industries.

1,3-Butadiene, BD is produced from C4-cut by extractive distillation. The separation of 1,3-Butadiene from C4-cut is not possible through the conventional distillation processes, because several mixtures have consisted of close boiling points constituents and make azeotrope. The BASF extraction distillation process in BD unit of Jam and Amirkabir Petrochemical Company improves the relative volatilities of components by addition of a high boiling point solvent (namely N- methylpyrrolidone, 8.3%wt H2O). With respect to high mass ratio of total solvent to feed, the solvent has significant role in separation. In this study, extractive distillation system was simulated with the HYSYS3.1 software to investigate the effect of the temperature and as well as that of feed entry stage of the solvent on the separation. It was found that; the reduction of solvent temperature had no considerable effect on products’ specifications, but rather, it could minimize the solvent rate.

In the case of industrial gas phase, slurry, or bulk polymerization it is very essential to keep the active catalytic components on a support. That is to achieve a polymer product with defined particle morphology. In this study a SiO2/TiCl4/THF/MgCl2 type of Bi-Supported catalyst was synthesized. The focus of which was on morphology and molecular weight. The catalysts were made of two different supports (LC, PQ-MS-3050.( Due to lower mechanical strength of LC and its un-controllable smashing during catalyst synthesis or polymerization, a catalyst with a poor morphology was obtained. Silica PQ-MS-3050 particles are spherical and hence resulted in polymers with a great percent of spherical particles. Due to appropriate mechanical strength of PQ-MS-3050, an acceptable morphology of the product was obtained. Replication phenomenon and fragmentation were investigated for the two synthesized catalysts using polymer melt and polymer ash microscopy. Because of the better morphology of PQ-MS-3050 supported catalyst, it was selected for molecular weight studies. An increase in hydrogen and co-catalyst concentrations and temperature, the molecular weight decreases. Four active centers were determined for PQ-MS-3050 supported catalyst by de-convolution of molecular weight distribution curves. These curves were obtained from GPC analysis for two samples polymerized at two different pressures. It was seen that the molecular weight is constant for each of the Flory components and a bimolecular chain transfer to monomer exists. Also, an increase in ethylene concentration produces a gradual decrease of polymer fractions produced by the centres I, II and III and a progressive increase in the fraction produced by the centre IV. It was also shown that monomer pressure increases with molecular weight. Therefore the centres with higher molecular weight have higher kinetic constants and an increase in ethylene concentration causes further increase in the fraction of the Flory components.

For the first time, this research reports the formation of nanoporous layers of metals on the surface of metal substrates by Raney method and their conversion to corresponding porous perovskite layers. The noble metals doped perovskites are used as catalytic converter for reducing automotive pollutants. The use of perovskite as a substrate for the noble metals can reduce the need for such metals by as much as 70%. The metal surface is treated by plastic deformation at high pressures or quenching to create microstructures, and then an aluminum-metal alloy layer is formed on the surface of the metal by its hot dip aluminizing at 750oC. At the same temperature, the aluminum is diffused into the metal surface layer as deep as 30nm for 1h. Subsequently the sample is gradually quenched or cooled and the aluminum is extracted by soda solution. Nanostructures of about 30 nm are obtained by combined Raney method together with the plastic deformation process. Quenching of the alloy creates even smaller nanostructures. The porous metal layer is impregnated with lanthanum nitrate for one or more times and calcined at 900oC to create the porous perovskite layer on the surface of the metal substrate as monolith. The perovskite completely converts CO and C2H6 (as representative of the exhaust unburned hydrocarbons).

We report the development of different types of oxygen sensors based on yittria-stabilized zirconia (YSZ) as a solid electrolyte. The conventional oxygen sensor is a concentration cell with two porous Pt electrodes, one of which is exposed to air as a constant (reference) oxygen concentration and the other is exposed to automobile exhaust gas of variable oxygen concentration, depending on the air-to-fuel (ATF) ratio injected into engine. The conventional sensor is miniaturized by using an oxide semiconductor instead of the reference air. This the response time and the sensitivity of the sensor significantly improved. Also the light-off time, during which most of large city pollutant are dramatically reduced. The transition response of above sensors occur at the stoichiometric ATF ratio, while recently lean-burn engines working at ATF ratios higher than that of stoichiometric are proffered. In addition to the above sensors, we have developed a new type of YSZ- based oxygen sensor, in which two oxides (e.g. TiO2, SnO2 and CeO2) with different semi conductive characteristics are applied on the tow Pt electrodes. This way the transition response of the sensor is shifted toward ATF ratios higher than the stoichiometric ones, suitable for lean-burn engines.

There is always the danger of fire in petroleum and gas industries. Fire destroys the steel structures of equipments. There are two methods to protect the equipments and steel structures against fire. One is the coatings which are based on intumeascent organic materials and are used for commercial and residential buildings with thermal resistance of up to 1000oC. The second type of coatings is based on inorganic material such as mica and vermiculite, which are used in the industry and are suitable for temperatures above 1000oC. The aim of this investigation was to study the mineral based coatings; using an analysis on a commercial sample; produced with various formulations and examined for fire protection properties by a direct flame experiment. X-ray analysis of the commercial sample showed that the main compounds for such coatings were Vermiculite, Mica together with other components such as Portland cement and gypsum and Montmorilonite. Various percentages of these materials were mixed in order to produce a formulation similar to that of the commercial one. A gas fired torch was directly used to heat one side of the samples having diameter 10 cm and thickness 3 cm. Three k-type thermocouples were used to measure the temperature on the other side. In all nine examined formulations; two were found to have properties very similar to the imported commercial sample. Several formulations and experiments were carried out & compared with the reference sample. Hence, the conductivity of (0.22W/moC) and heat capacity of (754.21kJ/kgoC) were achieved. These data were close to the reffernce standard.

It is several decades that the application of membrane processes for gas separation has become a great concern within industries. Among them, the polymeric membranes of different structures have played the most important role. Such application has been widely extended to gas separation and due to the necessity of both; prediction of the behavior of these processes and recognition of the effective parameters on membrane processes, in this research a mathematical model of mass transfer through polymeric asymmetric membranes is presented. Within the dense section of the membrane, a dual sorption model is applied, while for the porous section, the average effect of the four flow mechanisms; namely Knudsen, viscous, slip as well as surface flow are implemented. Basing on the experimental values of gas permeances through different membranes and by using a proper optimization method, the available membrane transport parameters were determined.

Iran is rich in mineral resources one of which is mineral Celestine. Basing on current estimations, the capacity of mineral Celestine is over two million tons, 75-95% of which is strontium sulfate. However; in industries such as Color cathode Ray Tubes (CRT), pyrochemical processes, ceramics, paint production, zinc purification processes; strontium sulfate is not a direct feed, rather it is largely consumed in the form of strontium carbonate. Two conventional methods are used to produce strontium carbonate from the sulfate; that is direct reaction and black ash methods. Strontium sulfide, as an intermediate component has a key role in black ash process including strontium sulfate reduction by coke, hence producing and leaching the strontium sulfide by hot water. Finally the reaction of strontium sulfate with sodium carbonate lead to strontium carbonate. In this paper, a system was designed to analyze and optimize the process parameters of strontium sulfide production which is less expensive and available solvent in water. Fundamentally, when strontium sulfide becomes in contact with strontium sulfate; Sr(SH)2 and Sr(OH)2 are produced. The solubility of strontium sulfide depends on water temperature and the maximum solubility achieved at 90oC. The results showed that in the experimental scale, at water to SrS ratio of 6; they sediment for 45 minutes at 95oC in five operational stages; the separation of 95 and 97.1 percent of imported SrS is possible in effluent of fourth and fifth stages, respectively. Thus; four leaching stages could be recommended for pilot scale plants. Also, the results show that at water to SrS ratio of 8, 40 minutes sedimentation at 85-95oC in one operational stage, the separation of 95 percent separation of inputted SrS, is possible. Solvent leaching process is continued till no smell of sulfur components is felt. It could be used as a key role to determine the number of leaching stages in experiments. Finally, the results show that the presence of Ba, Ca and other similar ions in the system, has no effect in the results of the analysis.

Due to the importance of Bacillus thuringiensis (Bt) in the biological fight, it is necessary to optimize its fermentation process and decrease its production cost. Statistical analysis is used not only to optimize fermentation conditions but also to describe and predict the culture behavior. In production of biological insecticide, one of the important phases is named as sporulation upon which, this work has been particularly focused on. The oxygen and culture time have an important effect on the production cost. So in the current research, the effect of such factors together with cell concentration, toxicity and sporulation has been considered. Regression analysis of the results, obtained in different conditions of aeration, showed that in all experiments, the percentage of total spores and mature spores increase with time. However, when saturated oxygen is used, this increase shows a very slow trend while in the case of interrupted aeration, the sporulation rate is so fast and the culture reached 100 % mature spore at 44th hours of fermentation. Toxicity and insecticide activity of fermentation product is significant even at the beginning of sporulation phase when time factor has only a positive effect at high oxygen concentrations.