Year:2005 | Volume:38 | Issue:5 (87)|Papers Count:14

In this paper a new method based on Pinch Technology is proposed for total cost targeting in Grass-Roots design of heat exchanger networks. This method considers allowable pressure drops and the effect of unequal heat transfer coefficients of streams in the earliest possible step (targeting) of heat exchanger network design. The proposed method uses individual temperature shifting of streams which is related to heat transfer coefficient of streams based on diverse pinch concept. It also considers the relations between pressure drops, heat transfer coefficients of streams and heat exchanger geometry in shell and tube heat exchangers to satisfy allowable pressure drops and reduce area and cost of heat exchanger networks. This method has been checked by a case study in which the results compared with assumed_h conventional method and fixed pressure drop conventional method .The findings indicate advantage of this new method in comparison with earlier methods

A continuous parallel-flow conveyor-belt dryer has been designed for drying of Picrite. The inlet wet solid moisture is about 81% and its outlet will be 0.2% and the thickness of the drying material is 2 cm. According to the general procedure of dryer design, first drying kinetics under conditions of thin-layer kinetics test method have been studied. Then modeling and design of conveyor-belt dryer has been carried out. The drying tests have been done at temperatures of 40°C, 60°C, 80°C and 100°C. The above tests were carried out at two different air flow rates. Interrelated curves including original, drying, drying rate, Krischer and temperature curves have been obtained. Data processing of these curves was used to determine other characteristics and parameters of the drying operation such as heat and mass transfer coefficients, moisture content, humidity, humidity of gas-solid interface, mass and heat diffusion coefficients. Also, through the modeling of this work, the dryer has been divided in two hindered and unhindered parts and equations of microscopic and macroscopic heat and mass balance have been derived and solved and subsequently, the final parameters and coefficients of this dryer have been obtained. The experimental device consists of a blower, a desiccator, steam supplier, orifice meters, heater, inlet and outlet psychrometers, drying duct and sampling unit. Accordingly, dynamic control of velocity, temperature and humidity of the flowing gas has been implimented.

Crude oils from the NW Iranian sector of Persian Gulf and Mesozoic and Tertiary source rocks have been characterized by means of a variety of organic geochemical techniques. The Biomarker characteristics (molecular fossils) were combined with other geochemical data to interpret the sources, depositional environments, digenesis and cat agenesis processes, migration and alteration. Oil fields investigated include Hendijan, Bahrgansar, Abouzar, Norowz, Dorood and Foroozan Fields in the NW part of Persian Gulf. Two groups of petroleum can be recognized in the Northwest of Persian Gulf on the basis of carbon isotope, biomarker investigation and statistical cluster analysis. Group 1, includes the Hendijan, Bahrgansar and Abouzar oil fields and based on the biomarker and other parameters, these oils sourced from the Upper Jurassic to lower part of the Cretaceous shaley rocks. Group 2, includes the Norowz, Dorood and Foroozan oilfields and was sourced from the Upper Permian to Middle Jurassic carbonate rock.

In order to investigate the effect of operational parameters on corrosion resistance of trication zinc phosphate coating on iron steels substrate in dip system, a series of experiments were done in laboratory. After salt spray test, a test that indicates the corrosion resistance of a painted film, the following results were obtained: for free acidity, when it was gradually increased, corrosion resistance of coating increased so that in a certain range, it achieved the best resistance; when it was further increased, the corrosion resistance decreased. For total acidity, it was observed again that within a certain range of total acid, the corrosion resistance of coating was high enough and out of this range decreasing of resistance was observed. As far as the time is concerned, in an initial range, corrosion resistance increased but after this initial range, no considerable change in resistance observed. For operational temperature, it was observed again that in a certain range of temperature the coating had its best resistance and out of that this resistance decreased. For accelerators concentration, in its low concentrations the corrosion resistance was more comparing to its high concentrations. And as far as the activators concentration was concerned, in lower concentrations the coating had higher corrosion resistance than in higher ones.

Understanding the changes in effective parameters in this processes and interaction of these parameters are important for increasing efficiency and quality of cathodic electrode position paint. The effect of operating parameters of cathodic electrode position paint on superior mechanical coating was evaluated in this research. The plates were prepared using 85 different states of voltage and temperatures. The following tests were used for evaluating superior mechanical of coating: adhesive, thickness, flexibility and corrosion resistant. All tests were carried out according to ASTM standard. The results showed that 35oC is a critical temperature for cathodic electrode position paint and a temperature higher than 35oC caused a reduction in coating properties, especially reducing corrosion resistant. Using voltage above the rupture voltage effected all of the coating properties and film properties were reduced severely. The results showed that the best temperature and voltage for 150-second reaction were ranged from 30 to 32 oC and 240 to 260 voltages respectively

Bioheap is a pretreatment process of refractory gold ores and concentrates. Gold recovery by cyanidation can be by pretreamt processes. The main advantages of bio-oxidation compared to other pretreatment methods are lower costs and more environmental desirable. Heap leaching of fine grain concentrates is not directly possible. In a recent process named "Geocoat", concentrate is coated on a support rock. In the present paper Mouteh gold concentrate was pretreated by Geocoat technique. The results obtained was statistically studied and interrelated. In this investigation three effective parameters on concentrate coating were studied. The results indicated that loading capacity of mill was the most important factor. Increasing residence time had no significant effect on the coating process. An economic faculty evaluation was required to determine the optimize residence time. Finally, the increasing number of spraying , cycles, increased coating percentage. Therefore, spraying of concentrate in a continuous manner would be the best choise.

The present paper deals with the leaching experiments carried out on a representative sample from Son gun oxidized zone in laboratory scale. The main goal was the evaluation of heap leaching of Son gun oxide ore. Son gun is one of the most important copper deposits in Iran. The copper reserve is estimated as 1.7 billion tons of sulfide and about 20 million oxide ores. In this study the effect of significant parameters, such as leach ability, leaching kinetics, acid consumption were examined and optimized. At optimum conditions, about 80% of Cu content was extracted by leaching columns. This figure was 95.2. % in case of bottle rolling tests

In this paper we will discuss about the development shaly models by using effective porosity versus true specific resistively cross-plots, which are affected by the shale group (Ash) in three states: layer, dispersed and total shale. By these methods we can get a realistic idea about the oil reservoir with natural fracturing. The response of equations of aforesaid models prepares some cross plots to calculate the percentage of water saturation. In the proposed methods there are three important parameters including: 1. Porosity parameter (m), which should not be considered equal to 2 and must be determined by trial and error. 2. Specific resistively of water (Rw ), which is measurable in the water-bearing reservoir. 3. All the analyzed shaly layer can be presented in the cross plots contain porosity, specific resistively affected by the shale group (Ash), even if shale volume changes monotonous and continuous. At the end, we discuss about two case studies by using cross plots which are very useful tools in analysis and evaluation of the layer, dispersed and total shaly models.

Axiomatic design is one of the design approaches. This approach is established on two axioms: Independence and information axioms. In this approach design matrix is a key concept. It is categorized to three types matrix with name uncoupled, decoupled and coupled design matrix. The uncoupled design matrix satisfies independence axiom. In this paper a new problem is presented in axiomatic design that is named Design Matrix Reconstruction. The recostructability of design relation matrix is investigated in this paper. Design relation matrix is used for presenting the relation between functional requirements and design parameters. For design relation matrix reconstruction, existence of some projections from unknown design matrix is supposed and on this basis some proofs are presented. These proofs show design relation matrix is reconstructible when the projections are consistence together. The design matrix reconstruction is applicable for reverse engineering, design evaluation and design improvement.

Globalization phenomenon intensifies the competition. In this environment companies have to optimize not only their internal process but also manage their members in supply chain and select the best of them. Supplier selection involves evaluation of many factors such as, cost of part/materials, transportation, quality, delivery performance, etc. Therefore, this problem is categorized in multi criteria decision making problem. Some researches have tackled this problem by application of analytic hierarchy process (AHP) which is a good method for qualitative analysis. In order to cover the quantitative analysis the Goal Programming (GP) has been applied simultaneously with the AHP to evaluate and select the supplier/s. Combination of these tools make very strong model for selection and planning the supplier/s. In order to validate the model, it has been compared with Bhutta & Huq (2002) model. The validation of the model has been completed by application of the model in an Iranian car company