Equilibrium constant vapor-liquid

Fig. 14. Vapor-liquid equilibrium constants for the //-pentane (l)-propane(2)-methane (3) system at 220°F.

Kij = vapor-liquid equilibrium constant between x, and v, for Stage j... 

C A constan denoting the cost of work per unit energy Fj Total molar flow rate of process stream j Hj Molar enthalpy of process stream j K Vapor-liquid equilibrium constant for component i Lj Liquid molar flow rate of process stream j... 

Here, V is the volume of the reactor, Qc, and QL are the gas and liquid flow rates, B is the vapor-liquid equilibrium constant (B = y/x, where y and x are mole fractions in vapor and liquid phase, respectively), and SL and va are the molar volumes of the liquid and gas phases, respectively, at reactor conditions. Similarly, for the gas phase, the following relation41 can be derived ... 

A more general way of expressing solubilities is through the vapor—liquid equilibrium constant m defined by... 

Vapor-liquid equilibrium constant and enthalpy value calculation routines... 

Thermodynamic calculations are used to evaluate vapor-liquid equilibrium constants, enthalpy values, dew points, bubble points, and flashes. Established techniques simulate the heat exchangers and distillation columns, and handle convergence and optimization. 

Cavett proposed the following problem as a test problem for computer-aided design. Four flash drums are connected as shown in Fig. P5.ll. The temperature in each flash drum is specified, and equilibrium is assumed to be independent of composition so that vapor-liquid equilibrium constants are truly constant. Is the problem properly specified, or do additional variables have to be given If the latter, what should they be The feed is as follows... 

Figure 7-5. Vapor-liquid equilibrium constants, -260 to -i-100°F. Source Hadden and Grayson [10].

Consider one mole per hour of a stream consisting of n volatile liquids with known compositions, and Xf i to be continuously separated into vapor and liquid streams at a given temperature and pressure (Reklaitis, 1983). It is desired to determine the steady-state flow rates of the vapor stream and of the liquid stream and their compositions. Let /f be the vapor-liquid equilibrium constants, Ki = yJXi, where X and are the liquid and vapor fractions, respectively. Ki is calculated from Raoult s law, A" = Pi(T)IP, where is the vapor pressure obtained from the Antoine equation. The flow rate of vapor stream, V, is obtained by solving the following nonlinear equation resulting out of the material balance on each of the species ... 

A mixture of benzene and toluene (50 1%) is fed to an evaporator at a rate of 100 kmol h , as shown in Figure Q2.20. The vapor effluent stream is 70 kmol h The uncertainty of each flow rate is 1%. The vapor-liquid equilibrium constant equals 1.78. Determine the fraction of benzene in the vapor phase and the uncertainty. The fraction of benzene in the vapour phase maybe calculated from the formula L.-D. Lafond... 

Vapor-Liquid Equilibrium Constants K(H20) - 0.319794E-(-02 mole/kg... 

Solubility. Another important application of equations of state in chemical process design is in converting solubility data to vapor-liquid equilibrium constants. The only equilibrium data that are available for such gaseous components as H2, N2, O2, CH4, CO, CO2, H2S, the acetylenes, etc., in such solvents as water, methanol, DMF, for example, are in the form of solubility data which may be found in Seidell (35) in the form of Bunsen and Ost-wald coefficients. 

Two-Phase Gas-Liquid Diffusional Operations The vapor-liquid equilibrium constant, defined as... 

Development of the turbo-expander process allowed design and construction of plants for recovery of liquid ethane, as well as the heavier hydrocarbon components. The turbo-expander extracts work from the gas during expansion from a high pressure to a lower pressure. Because of the work extraction the gas is cooled, and, by means of suitable heat exchange, temperatures as low as — 150°F (— 100°C) can easily be achieved. The separation at low pressure gives higher relative values of the vapor-liquid equilibrium constant... 

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