مجله فرآیند نو
پیاپی 61 (بهار 1397)

Efficiency of the utilized catalysts will significantly reduce after being in service for a certain time and should be replaced in the relevant processes. Although the spent catalysts are considered as solid waste materials, they have a potentially high economic value depending on the type of metals in their composition and the cost of the recovery process. Moreover, recovery of the heavy metals from the spent catalysts prevents environmental pollution. The main objective of this study was to investigate platinum recovery from the spent catalysts by Desferrioxamine B (Desferal) as a Siderophore compound for using in bioleaching process. According to the results obtained from full factorial design experiment and atomic absorption analysis the positive role of Desferrioxamine B in the platinum recovery was confirmed. The best efficiency of recovery at 70 Cº, pH=1, pulp density 1% and 4 g/l desferal was measured equal to 30% after 6 hours of treatment.

In this study four types of ceramic microfiltration membranes were fabricated by extrusion and sintering method; Mullite, mullite-alumina, mullite-alumina-zeolite and mullite-zeolite membranes. In order to ensure the correct fabrication of membranes, fabricated membranes were subjected to characterization tests such as scanning electron microscopy (SEM), X-ray diffraction (XRD), porosimetery, mechanical strength and mean pore size calculation. Synthetic oily wastewater were treated by these membranes in microfiltration-adsorption hybrid process. Effect of Powdered Activated Carbon (PAC) concentration on the membrane permeation flux, oil removal efficiency, turbidity and COD removal were investigated. Results showed that in mullite, mullite-alumina and mullite-alumina-zeolite membranes, highest permeate flux obtained in 800 mg L-1 of PAC concentration. For mullite-zeolite membranes addition of 200 mg L-1 PAC concentration lead to highest permeate flux. Addition of PAC with any concentration in all membranes increased oil removal, turbidity and COD removal percent significantly.

The energy and exergy analysis of a newhybrid loop heat pipe (LHP) heat exchanger trigeneration system is studied through energy and exergy efficiency parameters. The effect of exhaust gas inlet temperature on both energy and exergy efficiencies, and electrical to thermal energy ratio of the system are investigated. The energy efficiency increases with increasing exhaust gas inlet temperature but exergy efficiency and electrical to thermal energy ratio decreases. These results clearly show that performance evaluation of trigeneration system based on energy analysis is not adequate and hence more meaningful evaluation must include exergy analysis. The present analysis contributes to further information on the role of exhaust gas inlet temperature influence on the performance of exhaust gas recovery and solar trigeneration from a thermodynamic point of view. Decision makers should find the methodology contained in this paper useful in the comparison and selection of advanced exhaust gas recovery and solar systems.

Water pollutant is an issue that concerns all of the people. Considering the importance of the environment and water sources, in this study, simulation of refinery sour water purification unit has been investigated based on the determination of appropriate operating conditions. To predict the thermodynamic behavior of this system, Electrolyte NRTL activity coefficient model was used to simulate the sour water stripping tower. The simulation results showed that suitable feed temperature of column and tray spacing were 40 oC and 0.54 m, respectively. Also, the Concentrations of H2S and Ammonia reached to maximum amount at this conditions. Due to economic Considerations, feed volume flow rate of 38 m3/h was proposed.

Gamma alumina is one of the strategic materials, extensively used in the petroleum industries as catalysts and catalytic support. The present article was aimed to synthesize gamma alumina from aluminum nitrate by rapid auto-combustion technique in which urea and glycine were employed as fuels. In order to achieve this aim, the sonication and microwave techniques were applied for gel preparation and auto-combustion, respectively. The nano-sized gamma alumina powders were produced after calcination at 700 and 800 °C. The specific surface area of products was evaluated by adsorption of dye. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for characterization of powders. The obtained results indicated that the maximum dye adsorption is obtainable by microwave combustion and calcination at 800 °C.

The present study aimed at identifying the conceptual framework of key success factors in accepting reengineering of processes by quantitative and qualitative method in 1395. The statistical population of this research is in the qualitative section of the experts in the field of process engineering at the National Company for Distribution of Oil Products of Chaharmahal & Bakhtiari and in a small section of experts and technicians. After collecting the questionnaire and distributing it among the experts and calculating the initial matrix of the factors, it was found that 7 factors have a specific value of more than 1(hardware and software support, initial readiness (communication-cognitive), facilitation, motivation, Empowerment, Transparency, Confidence and Stabilization and Learning) that covered 65.054% of the variance of all variables. It was also found that 4 factors with a specific value of less than 1 (inefficiency of change management, inefficient managerial attitudes, inefficiencies in planning and environmental and cultural barriers), which covered 50.054% of the variance of all variables, and were identified as obstacles.