The shooting method and the difference method are used for numerical simulation of CO2 absorption with aqueous solution of methyldiethanolamine (MDEA). It is demonstrated that these methods are available for the stead...The shooting method and the difference method are used for numerical simulation of CO2 absorption with aqueous solution of methyldiethanolamine (MDEA). It is demonstrated that these methods are available for the steady-state model, which may be expressed as a set of differential algebraic equations (DAEs) with two-point boundary values. This method makes it possible not only to obtain the concentration profiles for MDEA system, but also to reveal the effect of CO2 interfacial concentration on the enhancement factor. With this numerical simulation, the mass transfer process with multicomponent diffusion and reactions can be better understood.展开更多
Vapor pressures were measured for six binary systems containing water, ethanol, or methanol with one of the two ionic liquids(ILs) at different component concentrations and temperatures using a quasi-static ebulliomet...Vapor pressures were measured for six binary systems containing water, ethanol, or methanol with one of the two ionic liquids(ILs) at different component concentrations and temperatures using a quasi-static ebulliometer,with the ILs mono-ethanolammonium formate([HMEA][HCOO]) and di-ethanolammonium formate([HDEA][HCOO]).The vapor pressures of the IL-containing binary systems are well correlated using the NRTL model with an overall average absolute relative deviation(AARD) of 0.0062. The effect of ILs on the vapor pressure depression of solvents at 0.050 mole fraction of IL is that [HDEA][HCOO]>[HMEA][HCOO], and the vapor pressure lowering degree follows the order of water>methanol>ethanol. Further, the activity coefficients of three solvents(viz. water,ethanol, and methanol) for the binary systems {solvent(1) + IL(2)} predicted based on the fitted NRTL parameters at T 333.15 K indicate that the two ILs generate a negative deviation from Raoult's law for water and methanol and a positive deviation for ethanol to a varying degree, change the relative volatility of a solvent. [HMEA][HCOO]may be a promising entrainer to efficiently separate ethanol aqueous solutions by special rectification.展开更多
Accurate modeling of the solubility behavior of CO_2 in the aqueous alkanolamine solutions is important to design and optimization of equipment and process. In this work, the thermodynamics of CO_2 in aqueous solution...Accurate modeling of the solubility behavior of CO_2 in the aqueous alkanolamine solutions is important to design and optimization of equipment and process. In this work, the thermodynamics of CO_2 in aqueous solution of N-methyldiethanolamine(MDEA) and piperazine(PZ) is studied by the electrolyte non-random two liquids(NRTL) model. The chemical equilibrium constants are calculated from the free Gibbs energy of formation, and the Henry's constants of CO_2 in MDEA and PZ are regressed to revise the value in the pure water. New experimental data from literatures are added to the regression process. Therefore, this model should provide a comprehensive thermodynamic representation for the quaternary system with broader ranges and more accurate predictions than previous work. Model results are compared to the experimental vapor-liquid equilibrium(VLE), speciation and heat of absorption data, which show that the model can predict the experimental data with reasonable accuracy.展开更多
文摘The shooting method and the difference method are used for numerical simulation of CO2 absorption with aqueous solution of methyldiethanolamine (MDEA). It is demonstrated that these methods are available for the steady-state model, which may be expressed as a set of differential algebraic equations (DAEs) with two-point boundary values. This method makes it possible not only to obtain the concentration profiles for MDEA system, but also to reveal the effect of CO2 interfacial concentration on the enhancement factor. With this numerical simulation, the mass transfer process with multicomponent diffusion and reactions can be better understood.
基金Supported by the National Natural Science Foundation of China （21076005） and Research Fund for the Doctoral Program of Higher Education of China （20090010110001）.
文摘Vapor pressures were measured for six binary systems containing water, ethanol, or methanol with one of the two ionic liquids(ILs) at different component concentrations and temperatures using a quasi-static ebulliometer,with the ILs mono-ethanolammonium formate([HMEA][HCOO]) and di-ethanolammonium formate([HDEA][HCOO]).The vapor pressures of the IL-containing binary systems are well correlated using the NRTL model with an overall average absolute relative deviation(AARD) of 0.0062. The effect of ILs on the vapor pressure depression of solvents at 0.050 mole fraction of IL is that [HDEA][HCOO]>[HMEA][HCOO], and the vapor pressure lowering degree follows the order of water>methanol>ethanol. Further, the activity coefficients of three solvents(viz. water,ethanol, and methanol) for the binary systems {solvent(1) + IL(2)} predicted based on the fitted NRTL parameters at T 333.15 K indicate that the two ILs generate a negative deviation from Raoult's law for water and methanol and a positive deviation for ethanol to a varying degree, change the relative volatility of a solvent. [HMEA][HCOO]may be a promising entrainer to efficiently separate ethanol aqueous solutions by special rectification.
基金the National Natural Science Foundation of China (51376188)the National Basic Research Program of China (2011CB710701)
文摘Accurate modeling of the solubility behavior of CO_2 in the aqueous alkanolamine solutions is important to design and optimization of equipment and process. In this work, the thermodynamics of CO_2 in aqueous solution of N-methyldiethanolamine(MDEA) and piperazine(PZ) is studied by the electrolyte non-random two liquids(NRTL) model. The chemical equilibrium constants are calculated from the free Gibbs energy of formation, and the Henry's constants of CO_2 in MDEA and PZ are regressed to revise the value in the pure water. New experimental data from literatures are added to the regression process. Therefore, this model should provide a comprehensive thermodynamic representation for the quaternary system with broader ranges and more accurate predictions than previous work. Model results are compared to the experimental vapor-liquid equilibrium(VLE), speciation and heat of absorption data, which show that the model can predict the experimental data with reasonable accuracy.
