The drop diameter dd is expressed in units of centimeters (cm), and the gas velocity uG in cm/sec.

When = 0.5 = 50%, Equation 5.18(7) can be solved for da = dac for a variety of QL/QG ratios. The solutions to these calculations are plotted as shown Figure 5.18.16. For these calculations, k = 0.25, /xG = 1.82 X 10~4 poises, and uG = vr with uG as a parameter ranging from 5 m/sec to 15 m/sec. Figure 5.18.16 can then be used to estimate dac for venturi scrubber operation at different QL/QG ratios and different throat velocities.

Rudnick et al. (1986) evaluated three widely used venturi scrubber equations (Calvert [1970], Yung et al. [1978], and Boll [1973]) and compared the equations with experimental data. They concluded that Yung's model, a modification of the Calvert model, predicts data better than the other two. However, the difference was not that great, and since the Yung model is complicated, the Calvert model remains useful for a first approximation of venturi scrubber performance.

The pressure drop across a venturi scrubber (in centimeters of water) can be estimated from the following equation (Leith, Cooper, and Rudnick 1985):

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