Equilibrium K values

L = mols of liquid at a specific temperature and pressure, from F, per unit time i = specific individual component in mixture Kj = equilibrium K values for a specific component at a specific temperature and pressure, from References 18, 65, 79, 99, 131, 235 T = temperature, abs... 

The ratio of equilibrium K-values for two components measures their relative volatility ... 

Simple phase equilibrium calculations, like the one illustrated here, can be readily implemented in spreadsheet software and automated. In practice, the calculations will most often be carried out in commercial physical property packages, allowing more elaborate methods for calculating the equilibrium K-values to be used. 

Also, the liquid-liquid equilibrium K-value needs to be defined for equilibrium to be... 

K = vapor-liquid equilibrium K-value For A = 1, the equation takes the form ... 

Whenever data are available for a given system under similar conditions of temperature, pressure, and composition, equilibrium distribution coefficients (K = y/x) provide a much more reliable tool for predicting vapor-liquid distributions. A detailed discussion of equilibrium K values is presented in Sec. 13. 

A hydrocarbon feed gas is to be treated in an existing four-theoretical-tray absorber to remove butane and heavier components. The recovery specification for the key component, butane, is 75 percent. The composition of the exit gas from the absorber and the required liquid-to-gas ratio are to be estimated. The feed-gas composition and the equilibrium K values for each component at the temperature of the (solute-free) lean oil are presented in the following table ... 

On the CD supplied with this book you will find Visual Basic software for the program RefFlsh. PPK equilibrium K values are calculated for each component in the program RefFlsh. Reference is made in the text to key code lines of this program. 

Mujtaba (1989) simulated the example considered by Boston et al. (1980) presented in section 4.2.4.1.1 using CMH model. The volume holdups used by Boston et al. were converted to molar holdups at the initial conditions. These were 0.00493 lbmol for each internal plates and 0.0493 lbmol for the condenser. Equilibrium k values were calculated using Antoine s vapour pressure correlation and enthalpies by the same procedure outlined in section 4.2.4.2.I. The simulation results are presented in Table 4.6. Note the slight differences in predictions (Table 4.4 and 4.6) are due to the use of different types of models (CVH and CMH) and thermodynamic property calculations. 

The hydrocracker simulator was also converted to subroutine form for inclusion in the nonlinear programming model of the Toledo process complex. The subroutine was considerably simplified, however, to save computer time and memory. The major differences are (1) the fractionation section is represented by correlations instead of by a multi-stage separation model, (2) high pressure flash calculations use fixed equilibrium K-values instead of re-evaluating them as a function of composition, and (3) the beds in each reactor are treated as one isothermal bed, eliminating the need for heat balance equations. 

CONVERGENCE-PRESSURE VAPOR-LIQUID EQUILIBRIUM K VALUES 1.49... 

Use convergence-pressure vapor-liquid equilibrium K-value charts (Figs. 1.15 through 1.26). 

Calculate dew-point equilibrium for the feed. A vapor is at its dew-point temperature when the first drop of liquid forms upon cooling the vapor at constant pressure and the composition of the vapor remaining is the same as that of the initial vapor mixture. At dew-point conditions, K, = A = Ki Xt, or Xj = Nj /Kj, and Nj /Kj = 1.0, where Yj is the mole fraction of component i in the vapor phase, Xi is the mole fraction of component i in the liquid phase, A is the mole fraction of component i in the original mixture, and Kj is the vapor-liquid equilibrium K value. 

Related Calculations. The convergence-pressure K -value charts provide a useful andrapid graphical approach for phase-equilibrium calculations. The Natural Gas Processors Suppliers Association has published a very extensive set of charts showing the vapor-liquid equilibrium K values of each of the components methane to n-decane as functions of pressure, temperature, and convergence pressure. These charts are widely used in the petroleum industry. The procedure shown in this illustration can be used to perform similar calculations. See Examples 3.10 and 3.11 for straightforward calculation of dew points and bubble points, respectively. 

The value of m, also known as equilibrium K value, is widely employed to represent hydrocarbon vapor-... 

Gas solubility has been treated extensively (7). Alethods for the prediction of phase equilibria and actual solubility data have been given (8,9) and correlations of the equilibrium K values of hydrocarbons have been developed and compiled (10). Several good sources for experimental information on gas— and vapor—liquid equilibrium data of nonideal systems are also available (6,11,12). 

Equilibrium K-value, Equilibrium constant for chemical reaction ... 

Algebraic Method for Concentrated Gases When the feed gas is concentrated, the absorption factor, which is defined in general as A = Lm/KGm where K = y°/x, can vary thronghont the tower owing to changes in the equilibrium K values due to temperature increases. An approximate solution to this problem can be obtained by snbstitu-tion of the effective absorption factors A, and A derived by Edmis-ter [Ind. Eng. Chem., 35, 837 (1943)] into the eqnation... 

Although these TFMKs are slow-binding inhibitors of HLE these are the equilibrium K. values. 

D,B = Distillate, bottoms flows, mols/hr K = Equilibrium K-value = Y/X... 

Equilibrium K value, t/j/xj Equilibrium constant for chemical reactionj Henry s constant for solute species 1 Molar or unit-mass solution property (A, G, H, S, U, V)... 

A useful formulation for VLE in separation calculations is the equilibrium K value defined in Eq. (15). 

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