A new theoretical thermodynamic model for the solubility of acid gases in aqueous solution of N-Methylidethanolamine

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.In gas sweetening, acid gases such as CO2 and/or H2S are usually removed by “chemical” absorption through aqueous amine solutions such as N-Methylidethanolamine (MDEA) solution. Reliable prediction of equilibrium properties (vaporliquid equilibrium and species distribution) is needed for a rigorous design of such absorption processes. Information on energy requirements can also be obtained from a reliable vapor−liquid equilibrium thermodynamic model. The currently used methods for correlating/predicting the simultaneous solubility of H2S and CO2 in aqueous MDEA solutions require accurate experimental solubility data of single and mixed gases, which, in general, confine their applicability in the experimental region. The purpose of this study is to develop a new theoretical thermodynamic model based on incorporating thermodynamic relationships that correlates the equilibrium and solubility constants to the Gibbs free energy of reaction, leading to an enhanced predictive capability of the model. In this work the Pitzer model is used to account for activity and specific ion interactive forces. This will allow to take into account the effect of the presence of all cations and anions such as thermally stable salts, dissolved organic species and amine degradation products that are usually encountered in absorption units. The suggested model can be a very powerful tool that could be of significant importance in the design of amine absorption processes as well as in simulations of the operating variables for optimization of gas sweetening systems.cf201

Incorporating Pitzer equations in a new thermodynamic model for the prediction of acid gases solubility in aqueous alkanolamine solutions

In gas sweetening, acid gases such as CO2 and/or H2S are usually removed by "chemical" absorption through aqueous amine solutions such as N-Methyldiethanolamine (MDEA) solution. Reliable prediction of equilibrium properties (vapor–liquid equilibrium and species distribution) is needed for a rigorous design of such absorption processes. Information on energy requirements can also be obtained from a reliable vapor–liquid equilibrium thermodynamic model. The currently used methods for correlating/predicting the simultaneous solubility of H2S and CO2 in aqueous MDEA solutions require accurate experimental solubility data of single and mixed gases which, in general, confine their applicability in the experimental region. The purpose of this paper is to develop a new theoretical thermodynamic model based on incorporating thermodynamic relationships that correlates the equilibrium and solubility constants to the Gibbs free energy of reaction, leading to an enhanced predictive capability of the model. In this work the Pitzer model is used to account for activity and specific ion interactive forces. This will allow taking into account the effect of the presence of all cations and anions such as thermally stable salts, dissolved organic species and amine degradation products that are usually encountered in absorption units. The suggested model has been verified through comparison with literature data for CO2 and H2S absorption. The presented model can be a very powerful tool that could be of significant importance in the design of amine absorption processes as well as in simulations of the operating variables for optimization of gas sweetening systems

Incorporating Pitzer equations in a new thermodynamic model for the prediction of acid gases solubility in aqueous alkanolamine solutions

In gas sweetening, acid gases such as CO2 and/or H2S are usually removed by chemical absorption through aqueous amine solutions such as N-Methyldiethanolamine (MDEA) solution. Reliable prediction of equilibrium properties (vapor–liquid equilibrium and species distribution) is needed for a rigorous design of such absorption processes. Information on energy requirements can also be obtained from a reliable vapor–liquid equilibrium thermodynamic model. The currently used methods for correlating/predicting the simultaneous solubility of H2S and CO2 in aqueous MDEA solutions require accurate experimental solubility data of single and mixed gases which, in general, confine their applicability in the experimental region. The purpose of this paper is to develop a new theoretical thermodynamic model based on incorporating thermodynamic relationships that correlates the equilibrium and solubility constants to the Gibbs free energy of reaction, leading to an enhanced predictive capability of the model. In this work the Pitzer model is used to account for activity and specific ion interactive forces. This will allow taking into account the effect of the presence of all cations and anions such as thermally stable salts, dissolved organic species and amine degradation products that are usually encountered in absorption units. The suggested model has been verified through comparison with literature data for CO2 and H2S absorption. The presented model can be a very powerful tool that could be of significant importance in the design of amine absorption processes as well as in simulations of the operating variables for optimization of gas sweetening systems

Laser cooling with intermediate state of spin–orbit coupling of LuF molecule

Abstract This work presents a theoretical study of the laser cooling feasibility of the molecule LuF, in the fine structure level of approximation. An ab-initio complete active space self-consistent field (CASSCF)/MRCI with Davidson correction calculation has been done in the Λ(±) and Ω(±) representations. The corresponding adiabatic potential energy curves and spectroscopic parameters have been investigated for the low-lying electronic states. The calculated values of the internuclear distances of the X3Σ0+ and (1)3Π0+ states show the candidacy of the molecule LuF for direct laser cooling. Since the existence of the intermediate (1)3Δ1 state cannot be ignored, the investigation has been done by taking into consideration the two transitions (1)3Π0+−(1)3Δ1 and (1)3Π0+ −X3Σ0+. The calculation of the Franck–Condon factors, the radiative lifetimes, the total branching ratio, the slowing distance, and the laser cooling scheme study prove that the molecule LuF is a good candidate for Doppler laser cooling