Samples of both the extract and raffinate are obtained as follows:
after leaving the extraction column, the supercritical carbon
dioxide containing the solubilized light fractions of palm fatty acid
distillate is expanded into the separator by pressure reduction
where the light fraction of palm fatty acids distillates are separated
from carbon dioxide. The heavy fraction of palm fatty acids distillates
are collected in the bottom of the column. The raffinate and
extract are collected at regular time intervals (60 min), by draining
the liquid reservoir under the bottom of the column and separator
respectively. This procedure is regulated with aid of both view cells. The view cells are installed at the bottom of the column and
at the separator in order to control the draining of liquid. The liquid
is drained until the point where its level reaches the lower part of
the view cell. This procedure has the advantage that solvent losses
(pressure drop) in both the extraction column and separator are
minimized. The solvent loss in both the extraction column and separator
causes not only a decrease in the system pressure but also
instabilities (e.g. variations on the solvent flow rate).