3.4.1. Calculation of the number of stages and solvent-to-feed
ratio
The separation of palmitic acid/(oleic + linoleic) acids from
palm fatty acid distillates mixtures in multistage countercurrent
columns using supercritical CO2 has been analyzed for the experimental
phase equilibrium points A, B, and C in Fig. 10. Information
concerning the selectivity ˛i,j and solubility of points A, B, and C
were used to evaluate multistage gas extraction process variables
(number of theoretical stages, solvent-to-feed ratio, reflux ratio,
product purity, and yield) with aid of short-cut methods (McCabeThiele
and Ponchon-Savarit). The analysis of separation process
variables related to the points A, B, and C provides the basis to evaluate what point or points should be selected to carry out extraction
experiments and the optimum process variables related to the
selected point, based on defined design criteria.