ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 9, pp. 1538!1543. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + N.A. Samoilov, I.A. Mnushkin, O.A. Mnushkina, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80, No. 9, pp. 1504 !
PROCESSES AND EQUIPMENT
OF CHEMICAL INDUSTRY
Specific Features of Operation of a Reaction!Rectification
Column in Different Feed Modes
N. A. Samoilov, I. A. Mnushkin, and O. A. Mnushkina
Ufa State Technical University of Oil, Ufa, Bashkortostan, Russia
Peton Limited Liability Company, Ufa, Bashkortostan, Russia
Received April 13, 2006; in final form, January 2007
Abstract-Various feeding modes (discrete and distributed) into a reaction!rectification column for produc-
tion of ethylene glycol are analyzed.
Interest in development of reaction3rectification ap-
paratus  combining a chemical process with separa-
tion of the reaction products has markedly increased
recently. Apparatus of this kind make it possible to
simplify the process scheme, diminish the capital ex-
penditure for construction of installations, and op-
timize the process as a whole [23 6]. Reaction3rec-
tification columns can be used in such processes as
esterification, hydrolysis, oxidation, alkylation, and
isomerization, in which the chemical stage occurs in
the boiling temperature range of components of the
reaction mixture on several contact mass-exchange
units of the column and, in particular, in synthesis
of ethylene glycol.
The most widely employed method for production
of ethylene glycol is direct hydration of ethylene
oxide, accompanied by a number of side reactions of
glycols with ethylene oxide to give diethylene glycol,
triethylene glycol, and tetraethylene glycol. To sup-
press the side reactions, industrial synthesis of ethyl-
ene glycol is commonly performed in the liquid phase
at elevated temperatures (~475 K) and pressures (1.53
2 MPa) in an excess of water .
Previously, a combined static-kinetic model of
operation of the reaction3rectification column has
been suggested . This model includes calculation of
the kinetics of the chemical process in the contact unit
of a column with that of the statics of fractionation
of the reaction mixture by the relaxation method.
A specific feature of the operation of the reaction3
rectification column in synthesis of ethylene glycol is
the possibility of recycling excess water within
the column to suppress side reactions at virtually
complete conversion of ethylene oxide and, according-
ly, operation of the upper part of the column in the
total reflux mode without distillate takeoff (Fig. 1a),
which improves the fractionation efficiency . In
this case, the feed (water and ethylene glycol, taken in
a 1 : 1 stoichiometric ratio) is introduced into one of
the contact units (plates) in the middle of the column,
mixed with the reflux composed of water with a minor
content of impurities, and subjected to a chemical
transformation to ethylene glycol with a minor admix-
ture of higher glycols. Further, the reaction mixture is
subjected to fractionation to give ethylene glycol with
admixture of water and higher glycols in the bottom
part of the column. Thus, the rectification process
Fig. 1. Schematic of a reaction!rectification column operat-
ing in the total reflux mode, with feed in different ways.
Feeding: (a) discrete and (b) distributed.