Appeal No. 2004-0495 Paper 22
Application No. 09/503,599 Page 6
in depth. The liquid volume in the collecting boiler at the bottom of the
column is approximately 22 liters (0.77 cu. ft.). Tube 5 feeds the product
from vessel 3 onto plate number 14 of column 7 and tube 6 feeds vapors
from vessel 3 into the space above plate 15.
Molten dimethyl terephthalate is fed continuously to vessel 3
through tube 1 at the rate of approximately 60 kg. per hour. At the same
time, ethylene glycol and catalyst are fed through tube 2 at the rate of
approximately 33 kg. per hour. ... The mole ratio of glycol to dimethyl
terephthalate fed to vessel 3 is approximately 1.7. Heat is supplied to
heating coils 4 to maintain a temperature of 185 o C. The mixture is stirred
by the bubbling of boiling methanol released by the exchange reaction.
Methanol vapors along with some glycol vapors are led through tube 6 to
column 7. The liquid mixture in vessel 3 overflows into tube 5 through
which it is directed to the reaction portion of column 7.
* * * * * *
The conditions in the column are regulated to give a pressure drop
from the bottom to the top of the column of 60 inches of water (112 mm of
mercury) The column is heated by coil 12 to maintain the temperature in
the calandria (reboiler 13) at 230±2o C., and partial condensor 9 is
adjusted to give an overhead take-off temperature of 70o C. Fresh glycol
is fed to the 17th plate at a rate of 5 kg. per hour. ...
* * * * * *
The product from outlet 11 of the ester interchange column is
immediately passed into a continuous polymerization system ... . [c. 4, l.
57 - c. 5, l. 60.]
Fresh glycol was added to maintain the desired ratio of ethylene glycol to dimethyl
terephthalate, i.e., "hot liquid glycol is supplied continuously in suitable quantity through
tube 15 onto a plate located above tube 6. Such an arrangement helps wash down
entrained dimethyl terephthalate from the upper plates and thereby helps prevent
plugging of the partial condenser." [See Figure; and, c. 4, ll. 27-35.]
The examiner does not disagree with appellants that Armstrong does not teach
or suggest feeding reactants at or below the midpoint of an ester exchange vessel
(Brief, p. 11, ¶ 2).
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