Liquids generalized density correlation

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.

The exponential dependencies in Eq. (14-195) represent averages of values reported by a number of studies with particular weight given to Lefebvre ([.Atomization and Sprays, Hemisphere, New York (1989)]. Since viscosity can vary over a much broader range than surface tension, it has much more leverage on drop size. For example, it is common to find an oil with 1000 times the viscosity of water, while most liquids fall within a factor of 3 of its surface tension. Liquid density is generally even closer to that of water, and since the data are not clear that a liquid density correction is needed, none is shown in Eq. (14-195). Vapor density also has an impact on dropsize but the impact is complex, involving conflicts of a number of effects, and vapor density is commonly omitted in atomizer dropsize correlations. 

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. 

Estimate the density of saturated liquid ammonia at 37°C (310 K, or 99°F) using (a) the Gunn-Yamada generalized correlation, and (b) the Rackett equation. The Gunn-Yamada correlation [16] is... 

Riazi and Whitson [21] They presented a generalized correlation in terms of viscosity and molar density that was applicable to both gases and liquids. The average absolute deviation for gases was only about 8 percent, while for liquids it was 15 percent. Their expression relies on the Chapman-Enskog correlation [Eq. (5-202)] for the low-pressure diffusivity and the Stiel-Thodos [AlChE J., 7, 234 (1961)] correlation for low-pressure viscosity ... 

For the liquid phases, the compressibilities are most commonly computed using the generalized correlations for liquids and analytical equations of state. Reid et alP describe in detail the various correlations available for the computation of liquid phase densities for pure components, with the modified Rackett equation being the most popular. For mixtures, the use of an analytical equation of state is most preferable with cubic equations of state being the favourite type of equation of state. 

The principal disadvantage of the RKJZ method is the complex temperature dependence of and Qb. Although Haman et al. (13) provided a generalized correlation for Qat and fib, these quantities are not generalized in the form described here but are generated each time they are needed from liquid densities and vapor pressures. Various sources of liquid density and vapor pressure are used versions of the Riedel correlations (14,15) API 44 Antoine equations (16) petroleum fraction correlations and curve fits of experimental information. 

Dispersion in liquid phase has been the subject of many investigations which were recently reviewed by Shah et al. (65). In general, the liquid phase dispersion depends mainly on gas velocity and column diameter. The overall liquid flow rate, the kind of gas sparger, and also physico-chemical properties like viscosity and density do not significantly effect liquid phase dispersion. The majority of all the measured data in various bubble columns can be described empirically by a correlation given by Deckwer et al. (42)... 

---