Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 11, pp. 1959−1964.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
A.V. Markova, 2009, published in Zhurnal Prikladnoi Khimii, 2009, Vol. 82, No. 11, pp. 1811−1816.
PROCESSES AND EQUIPMENT
OF CHEMICAL INDUSTRY
Selection of the Optimum Construction of Column
for the Periodic Rectiﬁ cation
A. V. Markova
St. Petersburg Chemical Pharmaceutical Academy, St. Petersburg, Russia
Received December 23, 2008
Abstract—The periodic rectification was considered from standpoint of recovery of the valuable component
from the waste products of pharmaceutical manufacture. On the bases of a suggested mathematical simulation
we developed an algorithm of computation and selection of an optimum configuration of a rectifying column of
periodic action in the stage of designing. An effect of an exhaustion degree and making a distillate stronger on
operating costs was examined in the determine example.
A problem of utilization of small amounts of waste
on small-scale manufactures is well-known. Recovery
of valuable components and their recycling are the main
task in designing nonwaste technologies. For instance,
solvent recovery in the production of extracts from plant
and animal raw material is a factor of effective use of
resources . For reuse of a solvent after its primary
distillation from the reactive mixture under conditions of
a ﬁ ne organic synthesis an additional improving treatment
is required. One of the ways to improve a primary
distillate quality is obtaining a highly pure product by
means of rectifying that should be carried out periodically
for small amounts of initial substances. Rectiﬁ cation is
a power-consuming process and a growing number of
pharmaceutical small-scale manufactures necessitates
forecasting power inputs already in the course of their
designing. An optimum column should be designed that
will operate under the better economy conditions in
comparison with other columns. The task of the column
selection in the stage of design still is not solved. So in
known communications [3, 4] there are no references
regarding the selection of the column conﬁ guration (reﬂ ux
number, number of trays). Only an idea is states on the
uncertainty of this subject.
The solution of the problem presented contains
a number of the difﬁ culties.
A criterion of optimality of the periodic process
suitable for this instance should be suggested since several
versions of its formulations are known . Furthermore,
a trend on variation of the reﬂ ux number must be planned
and that is extremely difﬁ cult in the initial stage of
the design. It is carried out on the basis of developed
techniques of the process calculation.
There are several techniques of the calculation of
the periodic rectiﬁ cation. The known detailed tray by
tray calculations of a column in the approximation to
the theoretical tray or taking into account the kinetic
coefﬁ cients [5−7] are labor-consuming and not always
reasonable since they do not ensure the accuracy of
the obtained results. The techniques based on the use
of experimental data  operate in the narrow range
of applications. Moreover only large enterprises can
venture building the pilot plants. And ﬁ nally, the possible
variation of a vapor and liquid column load should be
taken into account.
Therefore, the necessity of the development of simple
but general procedure of the selection of the optimum
column construction is obvios. The target of our report
was the development of the column selection strategy in
the stage of designing.
The suggested calculation techniques of the periodic
rectiﬁ cation are grounded on the following assumptions:
the column is strengthening, the trays are theoretical and
their number is constant. The height equivalent to the