Using density functional theory （DFT）, the thermodynamic parameters of the CO2 absorp-tion into the aqueous solution of the aliphatic amines including some alkylamines, alka-nolamines, diamines and a type of aminoam...Using density functional theory （DFT）, the thermodynamic parameters of the CO2 absorp-tion into the aqueous solution of the aliphatic amines including some alkylamines, alka-nolamines, diamines and a type of aminoamide were calculated. The geometry optimiza-tion and the calculation of vibrational frequencies in the gas phase were performed at the B3LYP/6-311＋ G（d,p） level of theory. Moreover, the standard solvation free energies of the studied species were computed upon the solution phase optimized geometries through the latest continuum solvation model （SMD/IEF-PCM） at the HF/6-31G（d） level of theory. With this approach, two important properties of the CO2 absorption into the aqueous so-lutions of the studied amines were evaluated： the acid dissociation constant （pKa） of the parent amines and the standard enthalpy change （ΔH^φabs） related to the CO2 absorption process. A roughly linear relationship was observed between pKa and ΔH^φabs. This finding suggests that a raise in the basicity of an amine leads to an increase in the heat released in CO2 absorption and consequently in the required energy for the regeneration of amine.展开更多
The absorption of acid gas using reactive amines is among the most widely used types of capturing technologies.However,the absorption process requires intensive energy expenditure majorly in the solvent regeneration p...The absorption of acid gas using reactive amines is among the most widely used types of capturing technologies.However,the absorption process requires intensive energy expenditure majorly in the solvent regeneration process.This study simultaneously evaluated the regeneration energy of MDEA and PZ/MDEA solvents in terms of heat of absorption,sensible heat,and vaporization heat.Aspen Hysys version 8.8 simulation tool is applied to model the full acid gas removal plant for the chemical absorption process.The new energy balance technique presents around the absorption and desorption columns to bring a new perspective of energy distribution in the capturing of acid gas plants.Sensitivity analysis of regeneration energy and its three contributors is performed at several operation parameters such as absorber and stripper pressures,lean amine circulation rate,solvent concentration,reflux ratio,and CO2 and H2 S concentrations.The results show that the heat of absorption of PZ/MDEA system is higher than that for MDEA system for the same operating conditions.The sensible heat is the main contributor in the required regeneration energy of MDEA solvent system.The simulation results have been validated against data taken from real plant and literature.The product specifications of our simulation corroborate with real plant data in an excellent approach;additionally,the profile temperature of the absorber and the stripper columns are in good agreement with literature.The overall results highlight the direction of the effects of each parameter on the heat of absorption,sensible heat,and vaporization heat.展开更多
文摘Using density functional theory （DFT）, the thermodynamic parameters of the CO2 absorp-tion into the aqueous solution of the aliphatic amines including some alkylamines, alka-nolamines, diamines and a type of aminoamide were calculated. The geometry optimiza-tion and the calculation of vibrational frequencies in the gas phase were performed at the B3LYP/6-311＋ G（d,p） level of theory. Moreover, the standard solvation free energies of the studied species were computed upon the solution phase optimized geometries through the latest continuum solvation model （SMD/IEF-PCM） at the HF/6-31G（d） level of theory. With this approach, two important properties of the CO2 absorption into the aqueous so-lutions of the studied amines were evaluated： the acid dissociation constant （pKa） of the parent amines and the standard enthalpy change （ΔH^φabs） related to the CO2 absorption process. A roughly linear relationship was observed between pKa and ΔH^φabs. This finding suggests that a raise in the basicity of an amine leads to an increase in the heat released in CO2 absorption and consequently in the required energy for the regeneration of amine.
文摘The absorption of acid gas using reactive amines is among the most widely used types of capturing technologies.However,the absorption process requires intensive energy expenditure majorly in the solvent regeneration process.This study simultaneously evaluated the regeneration energy of MDEA and PZ/MDEA solvents in terms of heat of absorption,sensible heat,and vaporization heat.Aspen Hysys version 8.8 simulation tool is applied to model the full acid gas removal plant for the chemical absorption process.The new energy balance technique presents around the absorption and desorption columns to bring a new perspective of energy distribution in the capturing of acid gas plants.Sensitivity analysis of regeneration energy and its three contributors is performed at several operation parameters such as absorber and stripper pressures,lean amine circulation rate,solvent concentration,reflux ratio,and CO2 and H2 S concentrations.The results show that the heat of absorption of PZ/MDEA system is higher than that for MDEA system for the same operating conditions.The sensible heat is the main contributor in the required regeneration energy of MDEA solvent system.The simulation results have been validated against data taken from real plant and literature.The product specifications of our simulation corroborate with real plant data in an excellent approach;additionally,the profile temperature of the absorber and the stripper columns are in good agreement with literature.The overall results highlight the direction of the effects of each parameter on the heat of absorption,sensible heat,and vaporization heat.
