Helmut Knapp

Gas solubilities in liquid solvents at high pressures: apparatus and results for binary and ternary systems of N2, CO2 and CH3OH

High-pressure, low-temperature absorption may be used to remove valuable or harmful components from gas mixtures. Information about the solubilities of the components in various solvents is necessary for the design of such processes. Predictions of vapour-liquid equilibria for the conditions in a high-pressure absorber are still inaccurate, and so reliable experimental data are required. The design of an experimental apparatus is described, and the results of measurements for temperatures 223 < T < 300 K and pressures 3 < p < 180 bar are reported.

Experimental and modeling studies on the solubility of CO2, CHC1F2, CHF3, C2H2F4 and C2H4F2 in water and aqueous NaCl solutions under low pressures

Solubilities of CO2, CHC1F2 (R22), CHF3 (R23), C2H2F4 (R134a) and C2H4F2 (R152a) in water and aqueous NaCl solutions containing salt 0.0121, 0.0291 and 0.0564 (mole/mole) were measured at three temperatures (278.15, 308.15 and 338.15 K) under low pressures (P < 0.1 MPa). The experimental apparatus consists of a degassing system and a gas absorption unit. Special attention was paid to degassing the solvents in order to obtain reliable solubility data under low pressures. The amount of gas dissolved in the solutions was determined by measuring the PVT data of the gas system. From the measured data, molar concentration of solutes on a salt-free basis and the Henry coefficients were determined. The EOS-approach proposed by Zuo and Guo (1991) was used for correlating the measured data. In this work, the short-range interactions were described by SRK-EOS coupling with van der Waals on fluid mixing rules, while the long-range interactions were represented by the modified Debye-Huckel model. Satisfactory calculation results were obtained.

Binary vapor-liquid-liquid equilibrium of dimethyl ether - water and mutual solubilities of methyl chloride and water: Experimental results and data reduction

Vapor-liquid-liquid equilibria in mixtures of dimethyl ether and water were investigated in a static equilibrium apparatus at pressures up to 1 MPa and temperatures 250 K < T < 350 K. Gas-solubilities, mutual liquid solubilities as well as vapor pressures of the immiscible two liquid phases in the system methyl chloride - water were determined. The conditions for the formation of a CH3Cl-hydrate were also investigated. Parameters of several gE-models were fitted to the experimental data and the reproducibility of the data with the gE-models was checked. New UNIFAC-parameters for the ether aliphatic - water interaction are reported.

Vapor pressures of n-butane, dimethyl ether, methyl chloride, methanol and the vapor-liquid equilibrium of dimethyl ether - methanol:: Experimental apparatus, results and data reduction

A static equilibrium apparatus for experimental investigations of vapor—liquid and vapor—liquid—liquid phase equilibria at pressures 10 kPa < p < 1 MPa and temperatures 250 K < T < 350 K was designed and built. The vapor pressure of n—butane was measured at 258 K < T < 357 K in order to test the operability and accuracy of the entire system. Vapor pressures of dimethyl ether, methyl chloride and methanol were measured; Vapor—liquid equilibria in the binary mixture of dimethyl ether and methanol were investigated. The experimental results were reduced.

Vapor — liquid and vapor — liquid — liquid phase equilibria of binary and ternary systems of nitrogen, ethene and methanol: Experiment and data evaluation

Zeck, S. and Knapp, H., 1986. Vapor—liquid and vapor—liquid—liquid phase equilibria of binary and ternary systems of nitrogen, ethene and methanol: experiment and data evaluation. Fluid Phase Equilibria, 26: 37–58. VLE and VLLE of three binary and one ternary system containing the components N2, C2H4 and CH3OH are investigated in a high-pressure phase equilibrium apparatus with vapor recirculation at temperatures 240 < T < 298 K and pressures 4 < p < 100 bar. Immiscibilities in the liquid phase are observed in the binary system C2H4CH3OH with a lower critical end point and in the ternary system N2C2H4CH3OH. The experimental results are reported and compared with the results of other investigators and of available correlations.

Isothermal measurements of vapor-liquid equilibria for three n-alkane-chloroalkane mixtures

Abstract Results of isothermal vapor-liquid equilibrium (VLE) measurements for 1-chlorobutane with n-hexane and n-heptane at three temperatures and for 1,2-dichloroethane with n-heptane at two temperatures are reported. New constants of the Antoine vapor pressure equation for 1,2-dichloroethane are presented. The consistency of the new vapor-pressure data with published experimental data of heat of vaporization is checked. The VLE data are used for the determination of group interaction parameters of UNIFAC and of the quasichemical group surface interaction model (QUAGSIM).

Thermophysical properties of binary liquid mixtures of polyether and n-alkane at 298.15 and 323.15 K: heat of mixing, heat capacity, viscosity, density and thermal conductivity

Abstract An apparatus for a rapid and simultaneous determination of the thermophysical properties excess enthalpy, isobaric heat capacity, kinematic viscosity, density and thermal conductivity has been developed. The experimental setup is subject of this paper. At 298.15 and 323.15 K, the systems ethylene glycol dimethyl ether–n-dodecane, diethylene glycol dimethyl ether–n-dodecane, triethylene glycol dimethyl ether–n-dodecane, tetraethylene glycol dimethyl ether–n-dodecane and diethylene glycol dibutyl ether–n-dodecane have been investigated. The experimental results are correlated and the macroscopic properties are interpreted.

Saturation of high pressure gases with low volatile solvents: experiments and correlation

Abstract The solubilities of methanol, toluene, acetone, n-heptane or n-nonane in nitrogen, methane or carbon dioxide are determined at temperatures of 240 K

Vapor—liquid equilibria in ternary mixtures containing nitrogen, methane, ethane and carbondioxide at low temperatures and high pressures

Phase equilibria in ternary mixtures containing N2, CH4, C2H6 and CO2 were studied with the purpose of supplying experimental data for testing and improving the accuracy and “truth” of theoretical models and equations of state including mixing rules. In this part T, p, x, y data are reported for CH4C2H6CO2 at T = 220.0, 233.1, 250.5 and 251.1 K and at p = 20, 30, 40 and 50 bar. The results are compared with those data calculated with generalized equations of state.

Solubilities of methane, propane and carbon dioxide in solvent mixtures consisting of water, N,N-dimethylformamide, and N-methyl-2-pyrrolidone

Abstract Gas solubility measurements were carried out in a glass apparatus by a synthetic method. The amount of gas absorbed in aqueous solutions of technical solvents was determined at several temperatures and solvent compositions. The experimental results were reduced to Henry, Ostwald, and infinite dilution activity coefficients as a function of temperature and composition of the solute free solvent. Then the enthalpy and entropy of solution were calculated. In addition the molar volumes of the solvent mixtures were measured.