مجله فرآیند نو
پیاپی 42 (تابستان 1392)

In quench towers and process water treatment section of steam generators, fouling decreases the performance, heat transfer rate, steam generation rate and increases rate of steam make-up for furnaces. In this study, Effective parameters like temperature, water contaminants, dissolved solids (e.g. Si, Fe,), PH, inhibitors and controlling chemical rates and dissolved oxygen which should be monitored for reducing these problems, are surveyed. Installation of dissolved oxygen monitor in dilution steam generator inlet stream is recommended as a result of this study. As this device provides the possibility of oxygen measurement, optimization of oxygen generating chemicals injection rates could be achieved. The recommended analyzer has not been available in olefin plants so far.

In this paper, we present an intelligent operator support system (IOSS) for detection of process upsets and determining their causes. The system uses a simple conventional back-propagation (BP) artificial neural network (ANN) to achieve its diagnostic purposes. However, the capability of the proposed methodology is enhanced to simultaneously diagnose multiple faults and their severity levels via employing a number of functional units to the network input layer. The effectiveness of the proposed approach has been examined through simulation study of a Heptane-to-Toluene process in steady state operation.

In the present work, a process is developed thatcould separate hydrogen sulfide (H2S) from acid gases with high selectivity. In this process, the main affecting parameters are: type of solvent, process layout and operating conditions. Due to limitation of commercial process simulators, the generic alkanolamines are investigated in this work. By using HYSYS process simulator software, in the first step, among the diisopropanol amine (DIPA) and N-methyldiethanol amine (MDEA) as selective absorbent of hydrogensulfide, the MDEA is selected as solvent. In the next step, by applying the experimental design techniques, the operating conditions regarding to the defined objective function, for three different processes layout are optimized. The optimum results for each case show that the second layout has maximum objective function and selectivity (the objective function is 1.6225 and the selectivity 3.3278) while regarding total energy consumption of the process, third layout with the value of total energy consumption 1.0108 kCal/h is the best layout.

Since energy efficiency of solar air heaters is low, a large number of researches have been carried out in order to increase the heat transfer coefficients. One of the methods is roughening the side of the solarized plate which is in contact with air flow inside the duct. In the present work, Nusselt number and friction factor in rectangular duct of a solar air heater and effects of roughness geometry and operational conditions on two mentioned parameters have been studied numerically. The numerical predictions have been compared to the experimentaldata. By considering results of the two ducts with V-shaped roughness and relative gap width (g/e) of 0.5 and 1.0 it can be realized that heat performance of the duct with g/e equal to 1.0 is better. Besides, by creating roughness on surface of heated plate, Nusselt number and friction factor became 6.16and 6.71 times greater than smooth duct. In the following, changing shape of roughness section from circular to triangular would lead to an increment in Nusselt number and friction factor as they were recorded 6.9 and 8.1 times greater than a smooth duct.

Unlike traditional drilling methods which often reduce the permeability of the rocks drastically, drilling method using laser technology increases the permeability of the rock and ultimately increases well oil production. Rock drilling using laser technology, is a process for removal of stones in which the thermal stress is used to break the stone into smaller pieces and removing debris and small stones left are carried out by the standard evacuation procedures. The rock laser drilling operation depends on wave laser parameters, beam characteristics and associated gas cleaning. The main objective of this article is studying pullsednd:yag laser technology strategy, in order to increase the penetration rate and rock drilling parameters that affect the use of lasers; also at the end of this article, the use of laser technology to reduce drilling costs, is presented.

The purpose of catalytic reforming unit is the production of high octane gasoline and aromatic components for petrochemical industries which are strategic and economic for Iran. But, the complexity of the naphtha feed, and unavailability of an appropriate kinetic package makes it difficult to simulate this unit using the commercial simulators such as Aspen plus and Hysys. In this research, performed on a fixed-bed catalytic reformer of a real refinery, at first this unit is simulated by using Aspen-plus simulator (ver. 2012), and applying the kinetic coefficients reported in the open literature. Then, the validity of simulation and its accuracy is studied and discussed in comparison with the actual test runs. Results show that the absolute average deviation (AAD%) of output temperatures of 1st, 2nd and 3rd reactors in comparison to actual data are 6.35, 0.79% and 0.74%, respectively. Additionally, the paraffin and aromatic content of produced gasoline in comparison to measured data are 2.17% and 2.46%, respectively. These results confirm the high accuracy of the developed simulator.