Nashrieh Shimi va Mohandesi Shimi Iran
Year:2006 | Volume:25 | Issue:1|Papers Count:11

ABSTRACT: The main purpose of this study is to optimize furnace performance in order to inimize the generation of pollutants. In this investigation COx, NOx, SOx and some combinations of them are considered as pollutants. Fuel type, the amount of excess air and preheated air temperature are chosen as main variables for optimization. Optional fuels are natural gas, gas oil and fuel oil. The objective function is a nonlinear polynomial equation consisting of air preheated temperature and excess air. Operation of optimization is performed with a computer program. Relationships between generation rates of NOx, COx and Sox and changing the preheated air temperature and excess air are used to generate necessary objective function parameters. Regression of a polynomial curve fitted to data obtained from above relations, will produce the necessary parameters required for the objective function. To solve this nonlinear objective function, “penalty function” method has been utilized. The result is the optimum values of air preheated temperature and excess air for a specific fuel type. The operation is then repeated for other fuel types and finally the best fuel type will be selected with the target of minimum generation of pollutants. A computer code is written with MATLAB language to handle the necessary calculation and process of optimization.

ABSTRACT: Biosurfactants are products of a wide range of microorganisms which have high level of surface activity. These are amphilye molecules constituted of hydrophobic and hydrophilic parts in this study, microorganisms separated from IRAN oil wells were used for biosurfactant production. After isolation of this organisems, its type was determined as pseudomonas aeruginosa. Main object of this study is optimization of pseudomonas aeruginosa growth condition to produce rhamnolipid. To do this, a mineral salts media is used and many different factors were studied. In an experiment to determine the best culture media for production of rhamnolipid, it was shown that between different mineral salts of 1M, 2M, 3M and 4M, the best culture media is 3M which in it, glucose is applied as carbon source. In rhamnolipid production is different incubation times intervals and conditions, it was shown that at fixed conditions of 2% inoculation, C/N=16, aeration=200 rpm, pH=6.8, T=30°C and 3M media, maximum production obtained after 96 hrs. After 24 hrs. rhamnose production is 0.06 g/l, at 48 hrs is 0.1, at 72 hrs is 0.17 at 96 hrs is 0.22, at 120 hrs is 0.15 g/l. In our experiments, maximum emulsification of crude oil in the condition of C/N=28, inoculation=2%, aeration=200 rpm, pH=7.5 and T=35°C has been 82.5 %.

ABSTRACT: Good Soils are among mineral which can be used as coagulator in 1970s, Russian scientiste found out zeolite have color lessing more than active carbon and in 1990 khantargavo showed natural zeolite like tofite have high capacity for refining Ismaylov has presented his last report on use of bentonite as coagulators. In order to control petrochemical wastewater and determining omition quantities, we use TOC and TUR changes. We use the best soils that does  the most omition. Our end is to compare all kinds of good soils can be used for precipitancy and refinding this wastewater. Soils investigated this research are 1) Tofite 2)Bentonite 3) Zeolite 4) Talc. Important issues are: 1) To choose mineral with maximum of coagulation. 2) Determining the speed of absorbing reaction and coagulation on different kinds of soils in different dose. 3) Studying effects of pH on coagulation quantities. 4) Inventing a simple and operative method to measure TOC, TUR in production line and comparing it with standard qualities. TUR & TOC changes measured to control effect of this soils. As a result Bentonite is the best soil that has maximum of absorbing of emulsion. This material have more reacting in alkaline and omit the emulsion of petrochemical and oil wastewater. Because activation of coagulation in alkaline environments is more than acid environments.

Optimum design of heat exchanger networks is an important subject in process design practice. Scientists and researchers have put a lot of effort to develop new methodologies for design and optimization of such networks, using both mathematical and conceptual approaches. In conventional pinch analysis, as a conceptual approach, an initial network is first synthesized using pinch design method, and then optimized by implementation of appropriate rules and techniques. However, these rules and techniques do not involve pressure drop considerations. In a recent research, new optimization methodology has been developed that includes three stages, each of which comprises many algorithms. The first stage of this methodology, which focuses on heat load optimization, is explained in this article. The method of heat load optimization in this paper is based on this loop breaking rules and techniques, and at the same time makes use of mathematical programming to find optimum point. Due to the differences between the nature of grass-root and retrofit projects, different procedures have been developed accordingly. These new procedures have also been applied to two case studies (Aromatics as grass-root, and crude distillation unit, as retrofit) and the results proved to be as expected.Having optimized the two initial networks, 4 percent improvement in total annual cost of aromatics network and 6.5 percent improvement in investment or 11 percent improvement in payback of the CDU network were identified.

The usage of cold contact processing can make the taste of the wort much better due to the reduction of non-accepted aromas such as 2-methyl butanal, 3-methyl botanal and hexanal, which have unpleasant taste. The comparison with the reduction rate of baldheads in cold contact processing and common fermentation and a process without any kind of fermentation is shown in this research. The aldehydes were extracted by some solvent such as hexan and were measured by gas chromatography. The result showed that the reduction of baldheads 65% in cold contact fermentation, 85% in common fermentation and only 20% in the process which has got just mashing and no fermentation which is due to some chemical intraction between baldheads and some particles in the wort. It should be added that beside noticeable baldheads reduction in cold contact processing which happens at the first hour of this process, the alcoholic amount in beer will be in the range of Iranian standard, but this amount of alcohol is too much in common fermentation which is against the Islamic rules and forbidden in this country.

The silica gel is produced in two main shapes, regular and irregular. Due to the decreasing of gas mobile phase pressure drop, increasing the contact surface area and lowering friction dust effects, spherical silica gel is used in the adsorbing towers of oil and gas industries. The most important methods for producing spherical silica gel are oil drop and molding. According to the studying and laboratory experiments done in this research, the oil drop method was selected. This method based on the immiscibility of silica sol (prepared from sodium silicate, sulfuric acid and other additives) with some organic oils and solvents. Dropped silica sol with a pH equal to 4 after passing through an oil phase is solidified into spherical hydrogen then spherical silica gel is produced after washing and drying steps. Therefore a granulating apparatus for producing spherical silica gel was designed and constructed, byu which a spherical silica gel having the technical characteristics of a one used in oil industries (red sorbead) was product.In this article many effective factors like pH of silica sol, oil temperature (65-70 °C), viscosity of the oil (46-67 cSt.) and hydrogel washing condition were have been studied.

Sodium chloride, being consumed by human being from long time ago, is one of the most important existing electrolytes in intercellular liquids of the body. The quality of Sodium chloride has always been an important issue because of its daily consumption and also its application in food industries. There is variety of methods to increase the quality of sodium chloride. Crystallization is one of the most common industrial methods to prepare food grade sodium chloride. In this method, different operational factors such as heat load transferred to the crystallizer, residence time, of magma in crystallizer, mixer speed and feed concentration affect  the purity and size of the produced salt. In the current research work an appropriate bench scaled crystallizer with a reservoir volume of 10 lit has been designed and implemented for quantitative investigation of the effects of these factors on sizing of sodium chloride crystals.In this paper, using taguchi analysis method, effects of all parameters on sodium chloride crystallization has been investigated in three different levels by running 9 double repetition tests (totally 18 tests) and the results have been statistically analyzed using qualitek-4 software. Test results show that heating load has the highest effect on crystal sizing of the final product while feed concentration and residence time have lower affects. The effect of mixer speed is negligible. Finally, the best operating conditions for production of crystalline salt has been determined to be feed concentration of 37% salt, mixer speed of 900 rpm, residence time of 60 minutes and heating load of 500 Watt.

ABSTRACT: Almost since 1960, research and examinations about air pollution, controlling and reducing different air pollutants, has been provided as a medical and environmental emergency issue and different methods for modeling and controlling air pollution has been proposed since then. In addition, during eighties and nineties pinch technology was used as an integration tool in heat and mass exchanger networks; respectively, and has wide application in reducing energy  and water consumption in these processes. In this research another application of pinch technology and total site is introduced which is the analysis of air pollution. While comparing different applications of pinch technology in this research, air pinch, grid diagram and composite concentration were drawn and the pinch point for the fresh air and the minimum required air for holding the limiting standards of pollution are put as targets.

The effect of fat percent at four levels (0.1, 1.19, 2.40 and 3.26%) on dynamic behavior of permeate flux (JP), total hydraulic resistance (RT) and mild solutes rejection (protein, RP; fat, RF; lactose, RL; minerals, RM and total solids, RTS) have been studied. Experiments were carried out using the pilot plant UF membrane system equipped to a spiral wound module and a polysulfoneamide membrane. A three-stage strategy based on an resistance-in-series model (boundary layer-adsorption) was used to determine the different hydraulic resistances. The results showed that the JP decreases greatly with increasing process time(t), but increasing fat percent only led to intial flux decline and it had no effect on pseudo steady state flux. RT increased during operation at all levels of fat percent. However RT, concentration polarization resistance, adsorption resistance and membrane hydraulic resistance did not change with increasing fat percent. The rejection results shwed that the RP and RF were constant at each value of fat percent and process time, whereas the RL, RM and RTS significantly increased.

ABSTRACT: New method is based upon seaboard process for natural gas sweetening. In this process, anaerobic baffled reactor (ABR) is used rather than aeration step. Microorganism to was provided by activated sludge from municipal sewage treatment, which was kept anaerobicaly for one year. This sludge was fed for two weeks with thiosulfate and then sulfide for 15 days in ABR with 5 compartments and active volume 10 l. Maximum sulfide removal rate reached was 3.03 mmol l-1. Microscopic observation showed that the dominant microorganism is Thiobacilli.  Taguchi method was used for optimization of nutritional needs of the microorganisms and to study the effect each nutrient on sulfur production and sulfide removal. The most important benefit of this process are: to eliminate seaboard process disadvantage, very fast start-up, high sulfide removal rate, using mixed culture and consequently increasing the possibility of industrialization of the process, lack of need for aeration and good response of the system to shock loading.