مجله فرآیند نو
پیاپی 60 (زمستان 1396)

Gamma alumina is widely employed in the petroleum industries as catalysts, catalytic supports and adsorbents. The present article was aimed to produce gamma alumina from Iranian kaolin because of limited sources of alumina. The powdered kaolin was converted into meta-kaolin by calcination and then leached to produce aluminum solution. Aluminum hydroxide was precipitated with ammonia from the leachate in the normal and ultrasound conditions. The powder of nano-sized gamma alumina was achieved after calcination. The specific surface area of powders was evaluated by adsorption of dye. Differential thermal analysis and thermogravimetry (DSC-TG), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning and transmission electron microscopy (SEM and TEM) were applied to characterize the powders. The synthesis of gamma alumina in the ultrasound condition not only reduces calcination temperature but also increases the adsorption efficiency up to 20 % which is due to the improvement in specific surface area.

The production of waxy crude oils from the oil fields is costly, complex, and has various problems depending on the conditions of each oil field and oil composition, among others. The majority of crude oils and their products contain substantial amounts of waxes called paraffin. The waxy crude oil behavior is a non-Newtonian flow behavior. This behavior causes complex equations. OLGA as a specialized software application is used for fluid transfer systems. In this work, simulation of waxy crude oil pipe line using by OLGA SOFTWARE was done. The obtained profiles include temperature, pressure, and thickness of wax layer at wall of pipeline. Also, the heat transfer coefficient of variation in the length at different times is obtained in this study.

In this paper, the performance of various heterogeneous catalysts, such as catalysts containing vanadium, molybdenum, rhenium and zeolites for converting methanol to methylal has been studied. The studies show that the vanadium oxide catalysts in comparison to other catalysts have shown the better performance. Catalyst V2O5/TiO2 prepared by impregnation method and modified in acid at a temperature of 423 K has shown 93% selectivity and 49% conversion of methanol to methylal. Also, in this study, change factors such as the number of acidic sites, reaction temperature and pressure, different methods for catalyst preparation, calcination temperature on catalyst performance were evaluated. These studies have shown that among the various listed factors, number of acidic sites has most important role in catalyst selectivity towards the production of methylal. Studies show increasing excessive acidic site has negative effect on catalyst selectivity toward the production methylal.

Although distillation is one of the most energy consumer processes, it is common in industrial units. Therefore, saving of energy in that is attractive for researchers. In this work, a thermodynamic analysis based on internal heat integration for distillation column with the aim of applying inter–reboiler and inter–cooler is presented. In this method, the exergy concept is employed to judge the quality of energy as well as a new driving force in order to thermal load and side exchanger position optimization. Also, this method makes it possible to evaluate energy saving. The simulation results of Debutanizer distillation column by using of proposed method show that many problems i.e.: temperature changes and errors in thermal load after replacing inter–reboiler and inter–cooler that have already occurred, did not happen in this method. Furthermore, using of this method leads to significant savings in required energy of column.

In this paper, a review has been conducted on integrated design of water network in process industries. First, the concept of water network synthesis has been defined and categorized in the two main groups of (i) Fixed mass load and (ii) fixed flow rate. In order to solve water network synthesis problems, two water pinch and mathematical optimization approaches are being used and the published researches related to each of these approaches are reviewed. In the end, the water consumption network and the limiting pollutants of water reuse in oil refinery are studied and some of the most important researches about solving this problem in oil refinery are presented considering different aspects such as the number of key pollutants, problem description and their solving approach points of view. Some studies reported that Water Pinch Analysis and could reduce water consumption in process significantly.

In this research, nanofluids heat transfer in a circular tube at turbulent regime were simulated and predicted by neural and neuro-fuzzy networks. Normalized Re numbers and volume fractions were inputs data and normalized heat transfer coefficient was output data. The average relative error and mean square error have been calculated. These values in the neural network are 0.002 and 0.0005, respectively. And for training data of neuro-fuzzy method were 0 and 0, for test data were -0.0027 and 0.00067, respectively. Regression value in neural network was 0.99. This value in neuro-fuzzy method for training data was 1 and testing data was 0.988. According to regression values, neuro-fuzzy method is better than neural network method.