Iranian Journal of Chemical Engineering (IJChE)

Abstract The present study numerically investigates the removal of hydrogen sulfide (H₂S) from crude oil using natural gas as a stripping medium in a T-junction microchannel through three-dimensional computational fluid dynamics (CFD) simulations. The microchannel geometry was adapted from a previously reported experimental configuration and further optimized to reduce natural gas consumption and operating temperature. The Volume of Fluid (VOF) model coupled with the SIMPLE algorithm was implemented in ANSYS Fluent to simulate the gas–liquid two-phase flow and evaluate mass transfer characteristics. Simulations were conducted for gas flow rates of 200–1200 mL/min and oil temperatures in the range of 20–40 °C. The results showed that the H₂S removal efficiency increased with crude oil temperature and gas flow rate but decreased with higher oil flow rate. The predicted efficiencies ranged between 65.7% and 77.8%, in close agreement with experimental data (maximum relative error: 5.6%). The cold-stripping configuration achieved high desulfurization performance even at low gas temperatures (about 18 °C) while reducing gas consumption by nearly one-third compared with conventional units. This study proposes validated correlations and optimized operating parameters for efficient desulfurization of sour crude oil using a microchannel-based cold stripping process.

Abstract In this research, the methods of oxidation, oxidation along with carbon nanotubes and surface absorption of carbon nanotubes were investigated to remove the drug substance of cefixime from aqueous solutions. In these methods, the removal percentage of cefixime was 78%, 96% and 70% respectively. Therefore, the results showed that oxidation with carbon nanotubes had a positive effect on the removal of cefixime. For this reason, oxidation along with carbon nanotubes was used to remove the cefixime. Next, different operating parameters such as the concentration of drug pollutants (20,30,40 and 55ppm), reaction time (5,10,15,20,25 and 30 min), concentration of hydrogen peroxide (1, 3 and 5ml) and amount of carbon nanotubes (0.05, 0.01 and 0.2 g/l) were studied in the removal process of cefixime using the method of  oxidation along with carbon nanotubes. It should be noted that in all experiments, certain amounts of carbon nanotubes and the oxidizing agent of hydrogen peroxide were used. In addition, a mixer, with a given round, was used to mix the materials. The maximum removal efficiency of cefixime from aqueous solutions is about 96% , which is related to the process of the removal of cefixime at the constant concentration of 55 mg/L by 0.1 g/L of carbon nanotubes and 5ml of hydrogen peroxide at the  t = 30 min.

Abstract The purpose of this research is CFD modeling of the fluid flow inside an industrial valve in order to discover the areas with high shear stress and to determine the effect of hydrodynamic on the erosion rate. CFD results are compared with the existing experimental data in a valid reference and the model is verified with high accuracy. The impact of the pressure at inlet and the disc angle on the erosion is investigated. By increasing inlet pressure, maximum velocity, turbulence intensity, wall shear stress and particle erosion increased. However, the wall shear stress, turbulence intensity, and particle erosion are clearly reduced as the disc angle decreases. When the disc angle is less than 50o, the range of dependent parameters changes has a small value. Reducing the disc angle or increasing the inlet pressure led to an increase in cavitation. Therefore, to prevent the erosion of the butterfly valve, it is necessary to increase the disc angle or reduce the pressure at inlet. Erosion of the butterfly valve significantly occurred at the front and rear of the disc. Depending on the disc angle, the shear stress of wall for the modified configuration is 10 to 80 times lower than the original butterfly valve. Therefore, it can be stated that the modified geometry can reduce the wall shear stress and consequently the erosive for all the disc angles of the studied butterfly valve.