New liquid–liquid equilibrium data for polyethylene glycol(PEG) 3000 + CHO_2K + H_2O systems were measured at 298.15 K and pH values of 7.95, 8.40 and 9.98. It was found that an increase in pH caused the binodal curv...New liquid–liquid equilibrium data for polyethylene glycol(PEG) 3000 + CHO_2K + H_2O systems were measured at 298.15 K and pH values of 7.95, 8.40 and 9.98. It was found that an increase in pH caused the binodal curve to be displaced downward and the two-phase region to expand. Accordingly, the binodal curve was adjusted to the Pirdashti equation and the tie-line compositions were correlated using the Othmer–Tobias, Bancroft and Hand equations. The study measured the refractive index and densities of several homogeneous binary and ternary solutions. The solutions were used for calibration within a range of 0% to 30% of the mass of the PEG and potassium formate. The density and refractive index data show a linear variation with the mass fraction of the polymer and the salt. The effect of pH on the binodal, tie-line lengths(TLL) and slope of the tie-line(STL) in the systems was examined. It was found that an increase in pH increased the TLL and decreased the STL. It was observed that the density of the aqueous two-phase system was influenced by the TLL. The difference in density between phases(Δρ) increased as the TLL and pH increased. It was found that the TLL and Δρ showed a linear relationship. The effective excluded volume(EEV) of the PEG was obtained and it was found that EEV also increased as the pH increased.展开更多
The process models for an equilibrium CO_2 absorber and a rate based CO_2 absorber using potassium carbonate(K2 CO3) solvents were developed in Aspen Custom Modeller(ACM) to remove CO_2 from a flue gas. The process mo...The process models for an equilibrium CO_2 absorber and a rate based CO_2 absorber using potassium carbonate(K2 CO3) solvents were developed in Aspen Custom Modeller(ACM) to remove CO_2 from a flue gas. The process model utilised the Electrolyte Non-Random Two Liquid(ENRTL) thermodynamic model and various packing correlations. The results from the ACM equilibrium model shows good agreement with an inbuilt Aspen Plus?model when using the same input conditions. By further introducing a Murphree efficiency which is related to mass transfer and packing hydraulics, the equilibrium model can validate the experimental results from a pilot plant within a deviation of 10%. A more rigorous rate based model included mass and energy flux across the interface and the enhancement effect resulting from chemical reactions. The rate based model was validated using experimental data from pilot plants and was shown to predict the results to within 10%. A parametric sensitivity analysis showed that inlet flue gas flowrate and K2 CO3 concentration in the lean solvent has significant impact on CO_2 recovery. Although both models can provide reasonable predictions based on pilot plant results, the rate based model is more advanced as it can explain mass and heat transfer, transport phenomena and chemical reactions occurring inside the absorber without introducing an empirical Murphree efficiency.展开更多
The equilibrium solubility of KCl ZnCl2 HCl(11%) H2O(25℃) quaternary system at 25℃ was determined and the phase diagram was constructed. This system is complicated with two new compounds K2ZnCl4·H2O (2∶1 type)...The equilibrium solubility of KCl ZnCl2 HCl(11%) H2O(25℃) quaternary system at 25℃ was determined and the phase diagram was constructed. This system is complicated with two new compounds K2ZnCl4·H2O (2∶1 type) and K5Zn4Cl13·3H2O (5∶4 type) which have been obtained from the system and have been characterized by XRD, TG DTG. The result shows that compound K5Zn4Cl13·3H2O of 5∶4 type is the new one which have not been reported before. For compound K2ZnCl4·H2O parameter of unit cell is a=11.976?, b=9.066?, c=7.015?, and it belong to orthogonal crystalline system. The result of TG DTG shows that compounds K2ZnCl4·H2O and K5Zn4Cl13·3H2O will dehydrate at 400℃ and 670℃, respectively.展开更多
Phase equilibria in the ternary system KCl-SrCl2-H2O at 25 ℃ was studied by using the isothermal method. Density and refractive index of the solution were also determined. The phase diagram was plotted according to t...Phase equilibria in the ternary system KCl-SrCl2-H2O at 25 ℃ was studied by using the isothermal method. Density and refractive index of the solution were also determined. The phase diagram was plotted according to the experimental data. In the equilibrium phase diagram of KCl-SrCl2-H2O, there is one invariant point, two univariant curves and two regions of crystallization: KCl and SrCl2·6H2O. In the invariant point, the composition of the liquid phase (mass fraction, wB) was wKCl 7.22%, wSrCl232.31%, the solid phase was KCl and SrCl2·6H2O. Neither double salts nor solid solutions between KCl and SrCl2·6H2O were found, and dehydration of SrCl2·6H2O didn′t occur in the system. The system is a simple eutectic type.展开更多
文摘New liquid–liquid equilibrium data for polyethylene glycol(PEG) 3000 + CHO_2K + H_2O systems were measured at 298.15 K and pH values of 7.95, 8.40 and 9.98. It was found that an increase in pH caused the binodal curve to be displaced downward and the two-phase region to expand. Accordingly, the binodal curve was adjusted to the Pirdashti equation and the tie-line compositions were correlated using the Othmer–Tobias, Bancroft and Hand equations. The study measured the refractive index and densities of several homogeneous binary and ternary solutions. The solutions were used for calibration within a range of 0% to 30% of the mass of the PEG and potassium formate. The density and refractive index data show a linear variation with the mass fraction of the polymer and the salt. The effect of pH on the binodal, tie-line lengths(TLL) and slope of the tie-line(STL) in the systems was examined. It was found that an increase in pH increased the TLL and decreased the STL. It was observed that the density of the aqueous two-phase system was influenced by the TLL. The difference in density between phases(Δρ) increased as the TLL and pH increased. It was found that the TLL and Δρ showed a linear relationship. The effective excluded volume(EEV) of the PEG was obtained and it was found that EEV also increased as the pH increased.
基金financial support from Peter Cook Centre for CCS Research
文摘The process models for an equilibrium CO_2 absorber and a rate based CO_2 absorber using potassium carbonate(K2 CO3) solvents were developed in Aspen Custom Modeller(ACM) to remove CO_2 from a flue gas. The process model utilised the Electrolyte Non-Random Two Liquid(ENRTL) thermodynamic model and various packing correlations. The results from the ACM equilibrium model shows good agreement with an inbuilt Aspen Plus?model when using the same input conditions. By further introducing a Murphree efficiency which is related to mass transfer and packing hydraulics, the equilibrium model can validate the experimental results from a pilot plant within a deviation of 10%. A more rigorous rate based model included mass and energy flux across the interface and the enhancement effect resulting from chemical reactions. The rate based model was validated using experimental data from pilot plants and was shown to predict the results to within 10%. A parametric sensitivity analysis showed that inlet flue gas flowrate and K2 CO3 concentration in the lean solvent has significant impact on CO_2 recovery. Although both models can provide reasonable predictions based on pilot plant results, the rate based model is more advanced as it can explain mass and heat transfer, transport phenomena and chemical reactions occurring inside the absorber without introducing an empirical Murphree efficiency.
文摘The equilibrium solubility of KCl ZnCl2 HCl(11%) H2O(25℃) quaternary system at 25℃ was determined and the phase diagram was constructed. This system is complicated with two new compounds K2ZnCl4·H2O (2∶1 type) and K5Zn4Cl13·3H2O (5∶4 type) which have been obtained from the system and have been characterized by XRD, TG DTG. The result shows that compound K5Zn4Cl13·3H2O of 5∶4 type is the new one which have not been reported before. For compound K2ZnCl4·H2O parameter of unit cell is a=11.976?, b=9.066?, c=7.015?, and it belong to orthogonal crystalline system. The result of TG DTG shows that compounds K2ZnCl4·H2O and K5Zn4Cl13·3H2O will dehydrate at 400℃ and 670℃, respectively.
文摘Phase equilibria in the ternary system KCl-SrCl2-H2O at 25 ℃ was studied by using the isothermal method. Density and refractive index of the solution were also determined. The phase diagram was plotted according to the experimental data. In the equilibrium phase diagram of KCl-SrCl2-H2O, there is one invariant point, two univariant curves and two regions of crystallization: KCl and SrCl2·6H2O. In the invariant point, the composition of the liquid phase (mass fraction, wB) was wKCl 7.22%, wSrCl232.31%, the solid phase was KCl and SrCl2·6H2O. Neither double salts nor solid solutions between KCl and SrCl2·6H2O were found, and dehydration of SrCl2·6H2O didn′t occur in the system. The system is a simple eutectic type.
