Abstract:In this work, the ability of a commercial spiral-wound nanofiltration membrane to remove hardness and ions from diluted seawater was studied. Experiments were carried out in the pressure range of 4-10 bar. Analyses of the samples, and permeates at different pressures, were performed and the effects of the trans-membrane pressure on the permeate flux were investigated. The results show that this nanofiltration membrane is capable of retaining 96-98% of the total hardness, 79-89% of the electrical conductivity and 79-89% of the total dissolved solid (TDS). Our results are in good agreement with those reported by the manufacturing company.

No abstract

No abstract

In this study, the experimental data for dissociation conditions of carbon dioxide hydrates in the presence of 0.05 and 0.1 mass fraction KCl solution + 0.1 and 0.2 mass fraction methanol and ethylene glycol were measured and then reported at different temperatures and pressure ranges not available in the related literature. The phase equilibrium curves were drawn using an isochoric pressure-search method. To validate the used apparatus and the experimental findings of the current study and also to show the inhibition effects of the aqueous solutions used in this study, the experimental values were compared with some selected experimental data from the literature about the dissociation conditions of carbon dioxide hydrates in the presence of pure water and aqueous solution with 0.05 mass fraction KCl. Finally, to examine the inhibitory effect of various inhibitors and their synergies on each other, the suppressed temperature for hydrate formation was evaluated in the presence of different inhibitor solutions. This value showed that the rate of suppressed temperature for hydrate formation for each solution has been almost constant in various pressures. The synergy effect of KCl with methanol or glycol at low concentrations is negligible indicating that these two inhibitors have no impact on each other. It was also shown that, by increasing the concentration of the inhibitors, this rule was violated, the inhibitors were affected by each other, and the amount of inhibition effect increases. This synergy is of utmost importance for oil and gas pipelines and also for the industrial equipment that naturally contain some salt, in which alcohol or glycol will be added to prevent hydrate formation.

In this study, hydrate dissociation conditions of carbon dioxide in the presence of methanol/ethylene glycol + CaCl 2 at the temperature range of 262.2−276.8 K and the pressure range of 1.49−3.36 MPa, not found in the related literature, were measured and reported. The equilibrium data were conducted by isochoric pressure search method. The experimental findings showed that methanol inhibition power was superior to that of ethylene glycol at similar mass concentrations. An available thermodynamic model was used to predict and compare the results with the measured experimental data. In addition, in order to investigate the inhibitory effect of various inhibitors as well as their synergy to one another, the suppressed temperature of hydrate formation in the presence of various inhibitory solutions used in this work and also in the similar studies in the literature was examined. This measurement indicated no effect of pressure on the reduction amount of suppressed temperature for each solution, so that it can be considered to be independent of pressure. Moreover, at low concentrations synergy level of CaCl 2 with methanol or ethylene glycol was negligible, indicating no effect of these two inhibitors on the performance of each other. By increasing the concentration of alcohol and glycol, this rule was interrupted and inhibitors interacted each other and the synergy level increased.