S. Faramarzi; A.H Oudi; S. Azimi; Y. Davoodbeygi
Abstract
Methanol is an important industrial chemical, and its synthesis and purification units are among the most widely used processes in the field of energy. The two-column separation unit of methanol has been analyzed from the thermodynamic and energy points of view in the present study. The simulation has ...
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Methanol is an important industrial chemical, and its synthesis and purification units are among the most widely used processes in the field of energy. The two-column separation unit of methanol has been analyzed from the thermodynamic and energy points of view in the present study. The simulation has been done by Aspen Hysys V11 and the SRK equation has been regarded as the most appropriate equation of state (EOS) for this simulation with the mean relative error (MRE) of 2 %. Then, the design of the heat exchanger network (HEN) has been calculated using the Aspen Energy Analyzer V11. Both distillation towers have been analyzed using pinch technology. As a result, the amount of hot and cold utilities used has been LP=1.482×〖10〗^8, MP=1.57×〖10〗^4, and Air =1.423×〖10〗^8, respectively. Besides, the total heating and cooling target of the process has been 1.482×〖10〗^8 and 1.423×〖10〗^8, accordingly. Then, the 〖∆T〗_min (minimum allowable temperature difference between hot and cold currents) and its effect on the annual cost have been investigated. The optimum value 〖∆T〗_min is determined to have better-operating conditions and to meet the design of the HEN economically. Reducing 〖∆T〗_min increases operating costs and reduces energy costs.
Modeling and Simulation
M. Hosseini; A. H. Oudi; Y. Davoodbeygi
Abstract
The fully mixed continuous stirred tank reactor is an important type of industrial reactors mainly used to produce high volume products such as petrochemicals, detergents, sanitary products and products that are in demand in the market. Knowing the dynamic behavior of chemical reactors is of great importance ...
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The fully mixed continuous stirred tank reactor is an important type of industrial reactors mainly used to produce high volume products such as petrochemicals, detergents, sanitary products and products that are in demand in the market. Knowing the dynamic behavior of chemical reactors is of great importance in setting up, designing, controlling and stopping reactors. In this paper, the effect of non-dimensional numbers Damkohler and Stanton on the stability of a continuous stirred tank reactor in which a first-order exothermic reaction takes place is investigated. First, a mathematical model of the system's dynamic behavior was presented. Then, by simultaneous solving of the equations of mass and energy around the fixed point in MATLAB software, the effect of the mentioned numbers was investigated. The results show that the continuous stirred tank reactor shows different behaviors in different ranges of Damkohler and Stanton numbers. This reactor behaves unstable in small and large ranges of Damkohler and Stanton numbers due to the presence of mixed or positive and negative eigenvalues. The best range for Damkohler and Stanton numbers is close to 1, because in this range the reactor shows stable behavior due to having two negative eigenvalues. In this range, in addition to the stability, the conversion is also 100%. Finaly the ratio of Stanton to DamKohler was investigated as St / Da˃1 and St / Da = 1. If St / Da = 1, the system is in steady state, but in St / Da˃1, the system moves away from steady state.
Reaction Engineering, Kinetics and Catalysts,
A. Irankhah; Y. Davoodbeygi
Abstract
One of the effective catalysts for hydrogen purification and production via medium temperature shift reaction, is Cu-Ce solid solution. Cu0.1Ce0,9O1.9 was produced using co-precipitation method and then was utilized as support for 5Cu/Ce0.9Cu0.1O1.9 catalyst which was synthesized employing wet impregnation ...
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One of the effective catalysts for hydrogen purification and production via medium temperature shift reaction, is Cu-Ce solid solution. Cu0.1Ce0,9O1.9 was produced using co-precipitation method and then was utilized as support for 5Cu/Ce0.9Cu0.1O1.9 catalyst which was synthesized employing wet impregnation method. X-ray diffraction (XRD) analysis showed that crystalline sizes of Ce0.9Cu0.1O1.9 and 5Cu/Cu0.1Ce0,9O1.9 were 9.22 and 18.33 nm, respectively. The Catalysts were evaluated in medium temperature shift reaction at 300-390 °C and at gas hourly space velocities (GHSV) of 12000 and 30000 h-1, in a fixed bed reactor. Due to higher concentration of Cu and synergic positive effects of both active metal and support, 5Cu/Cu0.1Ce0,9O1.9 catalyst showed better performance. It was also concluded that, because of low residence time at high levels of GHSV, increasing GHSV leads to decrease CO conversion. Then 5Cu/Cu0.1Ce0,9O1.9 was evaluated in microchennel reactor in 2 GHSVs of 12000 and 30000 h-1 and results were compared with the fixed-bed reactor. It can be concluded that microchannel reactor is better in higher GHSVs (lower residence time of gas flow). A microchannel reactor provides a high surface-to-volume ratio and gases pass over the thin layer of catalyst on the coated plates. Hence, due to the better access to the catalytic bed, the reactants react even in a short time, which improves the microchannel performance compared to the fixed bed reactor