the number of equilibrium stages in the column and the flow
rate of oil recycled. To illustrate the effect of the number of
stages, Figure 2 depicts depletion of FFA vs. stripping time
for 0 (no column at all), 1, 2, 3, 4, and 5 equilibrium stages in
the column. It can be seen that just one stage improves the
performance of the deodorizer significantly, after which the
impact is more modest; the optimal is at about 4 stages.
The optimal semi-batch design reduces the stripping time
by about 40% (batch conventional 3 h, semi-batch 1. 8 h). This
leads to an increase in productivity: The original 1,720 batches
per year can be increased to 1,845. The batch deodorizer is
the same for both alternatives, with a diameter D = 2. 5 m and
a height H = 5 m (half full with oil); the semi-batch alternative adds a pump of 1 K Watt, and the desorption column has
D = 1 m and a height that can contain 4 equilibrium stages
(which, with structured packing, is about 2 m).
The capital investment is about 25% larger in the semi-batch;
the operating costs also increase (mainly because the number
of batches increase) by 10%, but revenues increase 40% (due
to a larger production), which leads to a net increased benefit
of $75,000/yr with the semi-batch. This processing alternative
should be attractive for facilities that have already adopted
batch technology, and even more so if the raw material to
be deodorized is palm oil or bait, where the initial content of
FFA is high. In existing plants where deodorization is a bottleneck, the benefit will be more noticeable. In plants where
deodorization is not a bottleneck, semi-batch processing may
FIG. 1. Semi-batch process proposed in Laoretani and Iribarren
Carlson, K.F. (1996). In: Hui, Y.H. (Ed.), Deodorization,
Bailey’s Industrial Oil & Fat Products, 5th Ed., Vol. 4.
Wiley Interscience Pub., New York, p. 363 (Chapter 6).
Douglas, J.M. (1988). Conceptual Design of Chemical
Processes. McGraw Hill, New York.
Gavin, A.M. (1981). Deodorization and finished oil
handling, J. Am. Oil Chem. Soc. 58: 175–184.
Laoretani, D.S. and O. A. Iribarren (2017). Enhancing
the productivity of batch deodorizers for edible oils,
J. Food Eng. 192: 72–78.
O’Brien, R.D. (2009). Fats and Oils: Formulating and
Processing for Applications, 3d Ed. CRC Press, Florida,
FIG. 2. Content of free fatty acid (FFA) in oil as a function of
lead to a reduction of labor costs (reducing the number of
shifts required), and in the case of a new plant construction
project, the cost impact will be mainly due to a lower size of
Daniela S. Laoretani has a Ph.D. in Industrial Engineering
from Universidad Tecnológica Nacional–Santa Fe, Argentina.
Laoretani holds a postdoctoral position at CONICET, where
her area of interest is process design and integration in
the agroindustrial supply chain. She can be contacted at
Oscar A. Iribarren has a Ph.D. in Chemical Engineering from the
University of Massachusetts–Amherst, Massachusetts, USA.
He is a senior researcher at CONICET, where his area of interest
is process design and integration in the agroindustrial supply
chain. He can be contacted at email@example.com.