The influence of the reflux ratio on the HETP values at
373K and pressures between 26 and 29 MPa for the separation
palmitic/oleic + linoleic acids from palm fatty acid mixtures is illustrated
in Fig. 21. The results show that HETP values increase with
increasing reflux ratio holding both the liquid and solvent mass
flow rates constant. The results show that the HETP values can be
scaled as a linear function of the reflux ratio. For all the experi- ments for the separation palmitic/(oleic + linoleic) acids from palm
fatty acid mixtures, the HETP values computed with the McCabeThiele
method lies within the range 0.7 < HETP < 2.4. The high HETP
values obtained from experiments depend not only on the process
conditions, methods of calculation, but also on transport properties,
particularly the viscosity. Palm fatty acid distillate is a very
viscous fluid (palm fatty acid distillates are solid at temperatures
lower than 48 ◦C), and high viscous fluids inhibits the mass transfer
of solute molecules within the gaseous phase. Table 4 summarizes
the influence of solvent-to-liquid ratio, liquid load, and reflux ratio
on the HETP values.