Victor F. Yesavage

A rate-based model for the design of gas absorbers for the removal of CO2 and H2S using aqueous solutions of MEA and DEA

A rate-based model was developed for the design of acid gas absorbers using aqueous alkanolamine solutions. The model adopts the film theory and assumes that thermodynamic equilibrium among the reacting species exists in the bulk liquid. The diffusion-reaction equations for the reacting species in the liquid film are solved using collocation techniques. Heat effects accompanying diffusion and reaction are accounted for using appropriate heat balances on each tray. The algorithm adopts a plate-by-plate calculation starting at the bottom of the tower. Tray hydraulics was added to the algorithm to ensure proper operation of the tower. The program was developed to handle either monoethanolamine (MEA) or diethanolamine (DEA) as chemical solvents.

Predictions of the solubility of acid gases in monoethanolamine (MEA) and methyldiethanolamine (MDEA) solutions using the electrolyte-UNIQUAC model

Abstract A thermodynamic model was developed for representing vapor–liquid equilibria (VLE) of the CO 2 –H 2 S–MEA–MDEA–water system. The model accounts for chemical equilibria in the liquid phase and physical equilibria between the liquid and vapor phases. Activity coefficients are represented by the electrolyte-UNIQUAC equation. The present extension uses an ion-pair interaction approach and satisfies both the principles of like-ion repulsion and local electroneutrality. Contributions from long-range ion–ion interactions are represented by a Debye–Huckel formula suitable for mixed solvents, water and alkanolamines. Adjustable parameters of the electrolyte-UNIQUAC equation, representing short-range binary interactions, were determined by data regression using binary, ternary, and quaternary system VLE data. Predicted H 2 S and CO 2 vapor pressures are in good agreement with the reported experimental data for aqueous solutions of a single acid gas as well as mixtures of H 2 S and CO 2 in MEA and MDEA and their mixtures in the temperature range 25–120°C.

An apparatus for vapor—liquid equilibrium at elevated temperatures and pressures and selected results for the water—ethanol and methanol—ethanol systems

Abstract Niesen, V., Palavra, A., Kidnay, A.J. and Yesavage, V.F., 1986. An apparatus for vapor—liquid equilibrium at elevated temperatures and pressures and selected results for the water—ethanol and methanol—ethanol systems. Fluid Phase Equilibria , 31: 283–298. This paper presents a description of a system that is used to study vapor—liquid equilibrium at elevated temperatures (to 625 K) and pressures (to 10 MPa) for mixtures of compounds that are liquid at room temperature. In the evaluation of the equipment, results were obtained for the water—ethanol system at 150, 200 and 250°C and the methanol—ethanol system at 100 and 140°C. Liquid phase activity coefficients for these two systems were calculated using corrections determined from the modified Soave equation of state. The data obtained for these systems appear to be thermodynamically consistent.

Application of a maximum likelihood method using implicit constraints to determine equation of state parameters from binary phase behavior data

Abstract The maximum likelihood method has been modified to allow the use of implicit constraints in the determination of model parameters from experimental data and the associated experimental uncertainties. The use of the implicit constraints greatly facilitates phase behavior modeling since models typically are complex functions of pressure, temperature, volume, and composition. The new form of the maximum likelihood method is illustrated using recently obtained data for the binary systems m-cresol + quinoline, tetralin + quinoline, and m-cresol + tetralin. Parameters were obtained for six different mixing rules used in conduction with the Soave-Redlich-Kwong equation of state. The mixing rules ranged from a simple interaction parameter to more complex rules involving temperature and volume dependencies.

The enthalpies of 2,6-dimethylpyridine and m-cresol between 314 and 669 K and at pressures to 10.3 MPa

Abstract Experimental enthalpy measurements are reported for both 2,6-dimethylpyridine and m -cresol. The measurements were made in a high-pressure high-temperature flow calorimeter and cover the pressure range 0.34 to 10.3 MPa and the temperature range 314 to 669 K.

Development of a perturbed hard sphere equation of state for non-polar and for polar/associating fluids

Abstract A perturbed hard sphere equation of state was developed for both non-polar and polar associating fluids. First, a hard sphere equation of state, based on the Carnahan-Starling equation, with an empirical mean field attractive term was developed for non-polar fluids. The volume dependency of the attractive term was determined in order to reasonably describe volumetric properties of hydrocarbons. Hard sphere based equations of state have an almost temperature independent α(T) for spherically symmetric fluids compared to cubic equations. Thus, the α(T) expression used was the product of a term representing the slight temperature dependency for spherical fluids and a term, a function of the acentric factor, representing effects of shape for non-polar fluids. For polar fluids, a third polar factor was added to α(T) that used an effective acentric factor and a polar parameter.

Enthalpy of m-cresol between 291 and 655 K and at pressures of 207 and 690 kPa

Abstract Experimental enthalpy measurements were made on m -cresol along two isobars 206.8 and 689.5 kPa, and in the temperature range 291 to 655 K, using a reference-fluid boil-off calorimeter. In addition to the direct calorimetric results, estimated vapor pressures, ideal-gas enthalpies, and enthalpies of vaporization are also reported.

The enthalpy of thiophene between 326 and 664 K and at pressures to 10.3 MPa

Abstract Experimental enthalpy measurements were made on thiophene in the pressure range of 0.34 to 10.3 MPa and the temperature range 326 to 664 K using a high-pressure high-temperature flow calorimeter. Calculations made using the Kesler-Lee correlation and the Soave-Redlich-Kwong equation of state compare favorably with the experimental results.

Isobaric heat capacity measurements for the n-pentane-acetone and the methanol-acetone mixtures at elevated temperatures and pressures

Abstract Isobaric heat capacities for the n-pentane–acetone and the methanol–acetone binary mixtures were measured with a flow calorimeter at selected temperatures from 423.1 K to 523.1 K as a function of pressure up to 10 MPa. The compositions of each mixture were 0.25, 0.50, and 0.75 mole fractions. The uncertainties of cp measurements were less than 0.4%, depending on the magnitude of the temperature differences. As part of the measurement process, liquid densities at elevated pressure and 303.1 K were also determined and reported. Experimental cp data were compared to the cp values calculated using several equations of state. In general none of the equations of state were able to reliably predict the heat capacities in the supercritical region for either mixture. For both mixtures, the use of binary interaction parameters improved the cp representation in the critical region, by effectively translating the pressures that correspond to cp maxima. However, very close to a maxima, deviations of the calculated cp were still as large as 50%, due to the deficiencies of cubic equations of state in the critical region. Comparison results are specifically presented for the Peng–Robinson equation of state

Enthalpy of quinoline between 291 and 655 K at pressures to 10342 kPa

Abstract Experimental enthalpy measurements were made on quinoline along seven isobars from 207 to 10342 kPa, in the temperature range 291 to 655 K, using a reference-fluid boil-off calorimeter. In addition to the direct calorimetry results, equations for the liquid and vapor enthalpies as well as estimated values of vapor pressures, ideal-gas enthalpies, and enthalpies of vaporization are also reported.