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Kremser equations

The end points of the operating line on an XY plot (Fig. 15-13) are X., Y, andXy, Y., and the number of theoretical stages can be stepped off graphically. The equilibrium curve is taken from the Hand type of correlation shown earlier (Fig. 15-9). When the equilibrium line is straight, its intercept is zero, and the operating line is straight, the number of theoretical stages can be calculated with one of the Kremser equations [Eqs. (l5-14) and (15-15)]. When the intercept of the eqnihbrinm line is not zero, the value of YJK, should be used... [Pg.1461]

The solution to the Kremser equation is shown graphically in Fig. 15-14. When a system responds with a constant number of theoretic stages N, the solute concentration in the raffinate X can readily be evaluated as the result of changing the ratio of solvent to feed [Eqs. (15-17) and (15-18)]. [Pg.1462]

For cases B and C, Robbins ( Liquid-Liquid Extraction, in Schweitzer, Handbook of Separation Techniques for Chemical Engineers, McGraw-Hill, New York, 1979, sec. 1.9) developed the concept of pseudo solute concentrations for the feed and solvent streams entering the extractor that will allow the Kremser equations to be used. [Pg.1462]

On an XY diagram for case C the operating line will go through points Xr, Ys and Xf, with a slope of R /S similar to Fig. 15-13. When using the Kremser equation for case C, one uses the pseudo feed concentration X from Eq. (15-21) and the stripping factor from Eq. (15-22). One uses the raffinate concentration X and inlet solvent concentration Y, without modification. [Pg.1463]

For the first time through a liqmd-liquid extrac tion problem, the right-triangular graphical method may be preferred because it is completely rigorous for a ternary system and reasonably easy to understand. However, the shortcut methods with the Bancroft coordinates and the Kremser equations become valuable time-savers for repetitive calculations and for data reduction from experimental runs. The calculation of pseudo inlet compositions and the use of the McCabe-Thiele type of stage calculations lend themselves readily to programmable calculator or computer routines with a simple correlation of equilibrium data. [Pg.1463]

The concept of a mass-transfer unit was developed many years ago to represent more rigorously what happens in a differential contactor rather than a stagewise contactor. For a straight operating line and a straight equilibrium line with an intercept of zero, the equation for calculating the number of mass-transfer units based on the overall raffinate phase N r is identical to the Kremser equation except for the denominator when the extraction factor is not equal to 1.0 [Eq. (15-23)]. [Pg.1463]

Unfortunately, the analysis of chemical absorption is far more complex than physical absorption. The vapor-liquid equilibrium behavior cannot be approximated by Henry s Law or any of the methods described in Chapter 4. Also, different chemical compounds in the gas mixture can become involved in competing reactions. This means that simple methods like the Kremser equation no longer apply and complex simulation software is required to model chemical absorption systems such as the absorption of H2S and C02 in monoethanolamine. This is outside the scope of this text. [Pg.184]

If the equilibrium and operating lines are both straight, then the Kremser Equation can be used6 ... [Pg.185]

The Kremser Equation can still be applied if the equilibrium data can be linearized. From the slope of the equilibrium data at the raffinate stage (low concentrations) ... [Pg.189]

In applying the Kremser equation for xR > 0.0791, it must be recognized that the equilibrium line no longer intercepts the origin, but intercepts the xR axis at 0.02368. The concentrations, x p and x R, therefore need to be adjusted correspondingly ... [Pg.189]

For a dilute gas, and when the equilibrium curve can be approximated by a linear relationship passing through the origin, Eq. (25) is applicable, and an average absorption factor A can be applied to describe the contactor. Under these conditions, an analytical solution of the material balance equation and the equilibrium relationship is possible, giving the Kremser equation ... [Pg.16]

Horton and Franklin (1940) used the average absorption factor approach in analyzing a number of absorbers in the petroleum industry. Edmister (1943) extended the Horton and Franklin concept, retaining the Kremser equation form and making use of several empirical factors. He used an effective absorption factor Ae and a modified absorption factor A, given by... [Pg.16]

The calculation procedure in Table 6.22 could also be used for a multi-component mixture. After calculating the number of stages for separating the key component from the mixture, then the composition of all other components in the exit stream can be calculated using the Kremser equation, Equation 6.21.5A for absorbers or 6.21.5S for strippers. [Pg.334]

The extractor is at constant temperature and pressure, consistent with the inlet streams conditions. It is required to determine the extractor products flow rates and compositions using the Kremser equation described in Chapter 12, Equations 12.43 through 12.46. Additionally,... [Pg.379]


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