This, report develops computational techniques that are useful in multicomponent distillation. A design parameter, (∂n/∂N)s is introduced which is numerically equal to the number of theoretical plates required to do the work of one total reflux tray at the bottom of the enriching section. For a minimum sized tower, (∂n/∂N)s is legs than 3.5. Economic conditions may permit values as high as 6.
The ratio of the number of theoretical trays, n, to the minimum number, N, for the combined enriching and stripping sections, including reboiler and condenser, and the ratio of the reflux leaving the enriching section, Ls, to the minimum reflux, LMs, can be found from:
A total of 36 sets of minimum reflux data in multi-component systems were correlated with an average error of −4% in the ratio n/N by these equations.
Since (∂n/∂N)s is related to the relative volatility and the compositions of the counterflowing liquid and vapor streams at the bottom of the enriching section, the reflux Ls can be found from a feed tray balance. A procedure is provided for evaluating Ls after a value for the design parameter has been selected.