Gases generalized correlations

Generalized Correlations for Viscosity. Gas viscosity has also been predicted by corresponding states theory (90) using... 

Figures 9-21F and 21G (for Norton s IMTP packing only) can be up to 20% higher than industrial experience for the same Cj values at a flow parameter (FP) of 0.01 [82]. At an absolute colunrn pressure of 10 mm Hg or less, the pressure drop actual can be up to 30% lower than that read from the Figure 9-21F at the FP of 0.01 and the same Cg value [82]. The conclusion is that the generalized correlation, Figures 9-2IF and -21G always give a conservative design AP at operating pressures less than 70 mm Hg abs. Several other factors must be considered, such as variability of gas and liquid rates and densities or specific volumes.

Agitation of fermentation broth creates a uniform distribution of ah in the media. Once you mix a solution, you exert an energy into the system. Increasing power input reduces the bubble size and this in turn increases the interfacial area. Therefore the mass transfer coefficient would be a function of power input per unit volume of fermentation broth, which is also affected by the gas superficial velocity.2,3 The general correlation is expected to be as follows ... 

The mass transfer coefficient KLa is constant the general correlation is considered by many as proportional to the power per unit volume with constant exponent, and gas superficial velocity to another constant power as shown below 1,2... 

It was also shown both theoretically and experimentally (Tardos et al., 1985a,b) that there is a strong correlation between the excess temperature above the minimum sintering point, T-Ts, and the excess gas velocity above minimum fluidization conditions (measured below the sintering point) U-lJm required to maintain fluidization. A general correlation was developed between the excess temperature and the excess gas velocity, which takes the form... 

Note that for most cases of interest, T is close to unity since the flowing gas mass fraction x 1. For the case of frozen flow (i.e., no heat transfer between the two phases), T would be replaced by k (or CpJC . ) in Eq. (23-106). However, the difference between the two limiting cases is small (< 10 percent) in terms of the flow capacity [Leung and Epstein, A Generalized Correlation for Two-Phase Nonflashing Homogeneous Choked Flow, Trans. ASME J. Heat Transfer 112 (May), pp. 528-530, 1990],... 

Series 8 in combination with earlier series was intended to provide data on the effects of total anion concentration. The results are internally consistant with the correlation, having a standard deviation of about 15% around the mean error. However the measured values of PSO2 were about 40% lower than the general correlation. An SO2 analyzer, rather than iodine titration, was used to determine SO2 gas concentration from the saturator. The analyzer was calibrated with dry SO2/N2 span gas. In later experiments it was shown that humid gas gives a lower analyzer response. With constant fraction neutralization increased anionic concentration increases PSO2 because pH decreases faster than effective bisulfite activity. 

More recent literature regarding generalized correlational efforts for gas holdup is adequately reviewed by Tsuchiya and Nakanishi [Chem. Eng Sci., 47(13/14), 3347 (1992)] and Sotelo etal. [Inf. Chem. Eng., 34(1), 82-90 (1994)]. Sotelo et al. (op. cit.) have developed a dimensionless correlation for gas holdup that includes the effect of gas and liquid viscosity and density, interfacial tension, and diffuser pore diameter. For systems that deviate significantly from the waterlike liquids for which Fig. 14-104 is applicable, their correlation (the fourth numbered equation in the paper) should be used to obtain a more accurate estimate of gas holdup. Mersmann (op. cit.) and Deckwer et al. (op. cit.) should also be consulted. 

The fugacity coefficients in Equation (7.29) can be calculated from pressure-volume-temperature data for the mixture or from generalized correlations. It is frequently possible to assume ideal gas behavior so that 4>A = 1 for each component. Then Equation (7.29) becomes... 

Transform into an ideal gas at the initial conditions, evaluating property changes from a generalized correlation. 

Transform to ideal gas at initial conditions, generalized correlation for property changes. 

The generalized correlations for HR and SR, together with ideal-gas heat capacities, allow calculation of enthalpy and entropy values of gases at any temperature and pressure by Eqs. (6.45) and (6.46). For a change from state 1 ... 

Example 7,6 A stream of ethylene gas at 300°C and 45 bar is expanded adiabaticall in a turbine to 2 bar. Calculate the isentropic work produced. Determine the properti of ethylene by (a) equations for an ideal gas, and (b) appropriate general" correlations. 

Example 7.7 Propane gas at 20 bar and 400 K is throttled in a steady-state flow proto 1 bar. Estimate the final temperature of the propane and its entropy chang Properties of propane can be found from suitable generalized correlations. 

Jossi et al. (1962) presented a generalized correlation for the viscosity of high density fluids as a function of the reduced density via a corresponding states method. This method was discussed earlier. Among the gases that Jossi et al. (1962) used to build their correlation were carbon dioxide, methane, ethane, and propane. This gives us some confidence that this approach should be satisfactory for our acid gas mixtures. 

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