Process and Apparatus for Purifying Crude Alcohol and other Alcoholic Mixtures.
Year: 1896

page_text: Date of Application, 15th Dec., 1898-Accepted, 24th Apr., 1897
COMPLETE SPECIFICATION.
Process and Apparatus for Purifying Crude Alcohol and other
Alcoholic Mixtures.
I, CARL KILLING, Chemist, of 3, Gneisenaustrasse, Düsseldorf, in the German
Empire, do hereby declare the nature of this invention and in what manner the
same is to he performed, to be particularly described and ascertained in and by the
following stateinent :-
This invention is based on the discovery that if a mixture of vapours is formel
in a high evaporating chamber, the proportions between the different vapours will
vary according to the height from which the mixture is taken, or in other words,
that the mixture of vapours in the evaporating chamber forms progressive strata.
In utilising this discovery for the purification of crude alcohol, (inclusive of the
"first runnings" from stills), I employ an apparatus as illustrated by the accom-
panying drawing in which e indicates an upright cylindrical vessel filled up to a
portion of its height with crude spirit or "first runnings," f, and heated by a steam.
coils. The said vessel is also provided with a stirrer r, which can be set in motion
from the top by means of a crank; also at or near the top with a pair of adjustable
openings o and o' adapted to produce a slight current of air and with a thermo-
meter t, extending down into the liquid.
If the liquid mixture f be heated to 30°-40° Réaumur, not only the aldehyde
which boils at 20°, but also a portion of the ethyl-alcohol, which boils at 79°, will
slowly evaporate, for it is well-known, that liquids commence to evaporate long
before they reach their boiling point.
The mixture of the two vapours, however, varies from the surface of the liquid
to the top of the vessel, in such a manner, that the highest stratum contains almost
nothing but aldehyde and very little alcohol, because the latter forms drops d, or
strips, which trickle down along the walls of the cylinder and return to the liquid,.
while the aldehyde escapes through one or more of the openings o, o', or is led off
through a pipe.
The shape of the evaporating chamber or still, which the drawing shows as
cylindrical, is immaterial for this purpose, as long as it contains an evaporating
space of sufficient height.
The temperatures stated above have been found most advantageous for the
present case, but may be varied according to requirements; that is to say,
evaporation may take place also below 30° R. and above 40° R.
The dimensions of the evaporating space should be so chosen, that the vapour
drawn from the top will contain almost nothing but aldehyde and very little
ethyl-alcohol.
The process would be the same, if the vapours arising from the liquid were led
to a separate chamber, in which to effect the separation.
If it is desired to separate ethyl-alcohol from the admixtures which have a
higher boiling point, the temperature of evaporation must, of course, be higher
than in the example described.
The separation by my process is due to the difference between the boiling points
of the component vapours, the difference between their vapour tensions, the
difference between the speeds at which they evaporate, and between the speeds at
which they expand in the evaporating chamber.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is.-
1. The process for relieving crude alcohol or the first runnings from aldehyde,
which consists in causing the said liquid to evaporate slowly, allowing the vapour
to spread in a high evaporating space which is ventilated at the top and provided
with an upper outlet, the shape and dimensions of the apparatus being so arranged
that, owing to the progressive stratification or separation of the vapours ascending
in the evaporating space, the outlet of the latter contains chiefly aldehyde, while
the alcohol vapours are condensed in drops which run down the walls of the
evaporating chamber, substantially as described.
2. Apparatus for relieving crude alcohol or "first runnings" from aldehyde,
comprising in its construction a high receptacle provided at the bottom with a
heater and at the top with an adjustable outlet and air inlet o, o¹, the whole being
adapted to operate substantially as described.
3. The adaptation of the above described process and apparatus for purifying
alcoholic mixtures from impurities other than aldehyde.
Dated this 15th day of December 1896
FAIRFAX & WETTER,
433, Strand, London, Agents.