IMPROVEMENTS IN THE RECTIFICATION OF ALCOHOL AND IN THE METHODICAL SEPARATION OF MIXED LIQUIDS, AND IN APPARATUS BE EMPLOYED THEREIN
Year: 1880

page_text: LETTERS PATENT to Sydney Pitt, of Sutton, in the County of Surrey, for
an Invention of "IMPROVEMENTS IN THE RECTIFICATION OF ALCOHOL AND
IN THE METHODICAL SEPARATION OF MIXED LIQUIDS, AND IN APPARATUS
BE EMPLOYED THEREIN." A communication from abroad by the
Compagnie Industrielle des Procedés Raoul Pictet, of Paris, in the Republic
of France.
TO
PROVISIONAL SPECIFICATION left by the said Sydney Pitt at the Office
of the Commissioners of Patents on the 14th December 1880.
SYDNEY PITT, of Sutton, in the County of Surrey. "IMPROVEMENTS IN THE
RECTIFICATION OF ALCOHOL, AND IN THE METHODICAL SEPARATION OF MIXED
LIQUIDS, AND IN APPARATUS TO BE EMPLOYED THEREIN." [A communication from
abroad by the Compagnie Industrielle des Procedés Raoul Pictet, of Paris, in the
Republic of France.]
This Invention has for its object improvements in the rectification of alcohol and
in the methodical separation of mixed liquids.
In the processes employed at present in the rectification of alcohols the distil-
lations are carried on at temperatures ranging between 79° and 100°, the boiling
points of alcohol and water. Then the atmospheric pressure pervades the whole
apparatus, and the pressure of the vapours which form in the boiler are always
equal to the exterior pressure. In these conditions the mixed vapours of alcohol
and water are always made in the ratio of their densities and of their respective
tensions, and as between the limits of pressure indicated the ratio of the tensions
of the vapors of the two liquids is nearly as one is to two, there is a ccosiderable
difficulty in separating the two liquids and to carry on the rectification of the
alcohol.
In addition there are a number of secondary products giving off vapours between
79° and 100°; these empyreumatic products spoil the flavour of the alcohols and
depreciate their value.
These different conditions tend to raise the price of good alcohol, partly in

page_text: consequence of the expenditure of coal in fractional distillation, and partly of loss on
the alcohols of bad flavour.
1
It is endeavoured to overcome these difficulties by the following process
If the volatilization of water and alcohol be separately studied it is found that
in the low temperatures, between 25° and +40°, alcohol has vapour tensions that
-
are on the average four times greater than those of water.
On a similar study being made of mixtures of water and alcohol analysis shows
that the proportion of alcohol which is contained in a volume of vapour is slightly
more than proportionate to the tensions of the two liquids.
It results from these observations that if the distillation of a mixture of alcohol
and water be conducted at a low temperature the rectification will become easier as
the temperature is lowered.
Empyreumatic products not giving off vapour at these low temperatures are
retained entirely in the residual liquor, consequently the quantity of the fine
alcohol drawn over may be increased.
In short, if temperatures can be readily obtained, and if the distillation be carried
on at the temperature of the air, alcohol can be distilled and rectified without
expenditure of fuel, the motive power of the refrigerating apparatus replacing it.
I will describe shortly the arrangement of apparatus based on this principle.
The apparatus is composed of four essential parts, which are:-1. A boiler of
any convenient size. In this boiler a coiled pipe is arranged; it exposes an extensive
surface, and can be supplied with steam, hot water, or cold water; it communicates
heat to the liquor contained in the boiler.
2. A rectifying column similar to that which now forms part of most rectifying
apparatus, only the vapour passages are not covered by the liquid upon the
shelves.
3. A refrigerator condensor. This apparatus is a tubular boiler containing.
between the tubes a liquid which is kept at a low temperature by a refrigerating
apparatus of any suitable description. In the interior of the tubes the alcohol
which issues in the state of vapour from the top of the column condenses. This
refrigerator condensor is placed at a slight inclination, so that the condensed liquid
flows of its own accord into a reservoir, where it is collected without passing back
into the rectifying column.
4. An air pump, by means of which any desired pressure can be maintained in
the apparatus during the rectification.
The operation is carried on in the following manner :-A certain quantity of
liquor is introduced into the boiler, and tepid water or a current of steam is passed
through the coil of pipe so as to raise the temperature of the liquid to 30 or 40
degrees centigrade.
Then the pump is set to work; it withdraws the atmospheric air from the
apparatus, and as soon as a sufficient vacuum is contained the liquid commences
to boil, so that in a few minutes the air is expelled and is replaced by the vapours
of water and alcohol which rise from the boiler.
· A mercurial gauge becoming stationary indicates that this result has been
attained.
At this moment when the pump withdraws nothing but the vapours of water
and alcohol it may be thrown out of action by closing a cock between the air
pump and the reservoir, or by means of the three way cock a communication may
be made between the pressure side of the pump and the boiler, so that the vapours
drawn out may not be lost, but on the contrary serve to maintain an agitation
of the liquid in the boiler. As soon as the gauge has become stationary the liquid
contained in the condensor is cooled, and its temperature is reduced as low as the
refrigerating apparatus is able to carry it. For this purpose I propose to employ
anhydrous sulphurous acid introduced directly into the interior of the tubular
apparatus. A pump draws off the vapours of this volatile liquid, condenses it by
pressure in a condensor, and the condensed anhydrous sulphurous acid returns by
its own pressure into the refrigerating condensor. Ammonia, chloride of methyl,

page_text: oxide of methyl, sulphuric ether, and the like, may also be employed in place of
anhydrous sulphurous acid. A current of salt water cooled by any suitable process
may also be substituted for this volatile liquid.
'
Under the influence of the pressure and of the low temperature, which is
artificially produced in the tubular apparatus, the vapours of alcohol and water
condense in the tubes of the condensor, and the mixture runs to the lowest part,
where there are two cocks side by side.
One cock opens or closes communication between the refrigerating condensor
and the reservoir.
Another cock opens and closes communication between the refrigerating condensor
and the top of the rectifying column.
These two cocks are opened to such an extent that about half of the liquid con-
densed in the refrigerating condensor returns into the column whilst the other half
is diverted into the reservoir.
In consequence of this arrangement the alcohol becomes more and more rectified,
and after a little time the alcohol which passes into the reservoir marks 96 to 97
degrees.
To hasten the distillation a wheel agitator is immersed in the boiler and kept
in constant movement. The effect is to favour the evaporation of the alcohol and
to mix more intimately the superficial with the deeper layers of the liquid.
When the operation has well commenced it is only necessary to pass through
the coil in the boiler a current of water at ordinary temperature which yields heat
to the alcohol and maintains the distillation indefinitely.
When almost the whole of the alcohol is distilled the temperature may be some-
what raised to drive over the last traces of this liquid.
It is advisable to surround the rectifying column, and the reservoir, and all the
pipes with some bad conductor of heat. The alcohol collected in the reservoir is
rectified and ready for the market.
With an hydraulic motor working the refrigerating apparatus it is thus possible
to distill and to rectify alcohol without expenditure of fuel.
Such then in substance are these improvements in the treatment of alcohols,
applicable equally to the separation of all mixed volatile liquids, such as those
employed in perfumery, and so forth.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Sydney Pitt in the Great Seal Patent Office on the 13th June
1881.
SYDNEY PITT, of Sutton, in the County of Surrey. "IMPROVEMENTS IN THE
RECTIFICATION OF ALCOHOL, AND IN THE METHODICAL SEPARATION OF MIXED
LIQUIDS, AND IN APPARATUS TO BE EMPLOYED THEREIN." A communication from
abroad by the Compagnie Industrielle des Procedés Raoul Pictet, of Paris, in the
Republic of France.
This Invention has for its object improvements in the rectification of alcohol,
and in the methodical separation of mixed liquids, and in apparatus to be employed
therein.
In the processes employed at present in the rectification of alcohols the distillations
are carried on at temperatures ranging between 79 and 100 degrees centigrade, viz.,
the boiling points of alcohol and water; then also the atmospheric pressure pervades
the whole apparatus, and the pressure of the vapours which form in the boiler are
always equal to the exterior pressure. In these conditions the mixed vapours of
alcohol and water are always made in the ratio of their densities, and of their
respective tensions, and, as between the limits of pressure indicated, the ratio of
the tensions of the vapours of the two liquids is nearly as one is to two, there is a
considerable difficulty in separating the two liquids and to carry on the rectification
of the alcohol.
In addition there are a number of secondary products giving off vapours between
79 and 100 degrees; these empyreumatic products spoil the flavour of the alcohols,
and depreciate their value.
These different conditions tend to raise the price of good alcohol, partly in
consequence of the expenditure of coal in fractional distillation, and partly of loss
on the alcohols of bad flavour.
It is endeavoured to overcome these difficulties by the following process:-
If the volatilization of water and alcohol be separately studied it is found that
in the low temperatures, between 25° and +40°, alcohol has vapour tensions that
-
are on the average four times greater than those of water.
On a similar study being made of mixtures of water and alcohol analysis shews
that the proportion of alcohol which is contained in a volume of vapour is slightly
more than proportional to the tensions of the two vapours.
It results from these observations that if the distillation of a mixture of alcohol
and water be conducted at a low temperature the rectification will become easier as
the temperature is lowered.
Empyreumatic products not giving off vapour at these low temperatures are
retained entirely in the residual liquor, consequently the quantity of the fine
alcohol drawn over may be increased.
In short, if low temperatures can be readily obtained, and if the distillation be
carried on at the temperature of the air, alcohol can be distilled and rectified
without expenditure of fuel, the motive power of the refrigerating apparatus
replacing it.
"I will describe the arrangement of apparatus based on this principle.
DESCRIPTION OF THE DRAWINGS.
The apparatus in its simplest form is shown in section on Sheet 1 of the

page_text: in Figure 4, which is supplied with steam, warm water, or other fluid with a
view to bring to a suitable temperature the liquor or wash contained in the
boiler.
2. A column containing shelves B, Figure 1. This column is similar to those
employed in rectifying apparatus. The shelves are hollow, and have a flange
around them; they are fixed by their edges to the interior of the column; they
may also be arranged in any other convenient manner; they are alternately round,
filling the whole section of the column, and square, as is seen at Figure 3. The
round shelves give passage to the ascending vapours by a hole with a rim around
it; this hole is in the middle of the shelf, as is seen in Figures 1 and 2. The
vapours, on the contrary, are obliged to pass by the outer edges of the square
shelves, as is seen in Figures 1 and 3. The vapours are thus constantly baffled in
their course, and are thus brought into more intimate contact with the liquid
retained upon the shelves, which separates the less volatile portions carried by
them.
3. A refrigerating condenser C. This apparatus is similar to a tubular boiler.
The chambers at the two ends communicate the one with the other by tubes,
through which the vapours pass on coming from the column containing the trays.
The space between the tubes contains a cooling liquid, which maintains the
tubes at a temperature sufficiently low to condense the alcoholic vapours. The
refrigerator is slightly inclined, so that the liquid resulting from the condensation
may flow of itself into the receiver D placed below.
4. An exhausting and forcing pump E of any convenient construction, which
exhausts the interior of the boiler A, the column B, and the refrigerating tubes C,
and removes from them all the air which they contain, so that the rectification may
take place in a partial vacuum, corresponding to the desired boiling point of the
alcoholic liquid. This pump consists of a cylinder, in which works a piston
actuated by any suitable motor. A double set of valves working different ways
draws in air from the apparatus at each movement of the piston, and expels it into
the atmosphere. At the commencement of the operation the air thrown out being
mixed with alcohol a part of it can be directed into the boiler A to return the
alcohol which it contains. Nevertheless it is preferable not to do so, because of the
air, which is thus returned to the apparatus.
The operation is conducted as follows:-
The wash or alcoholic liquid to be rectified is put into the boiler A, and at the
same time warm water is made to pass through the coil within it, so as to establish
in the boiler a temperature of from 20 to 40 degrees, according to the nature of
the alcoholic liquid under treatment.
The pump E is then set to work to remove the air from the apparatus. During
this time the three way cock R is turned to such a position that the outlet from
the pump is into the outer air. At the end of a few minutes the air is expelled
and is replaced by the vapour of water and alcohol.
A mercury vacuum gauge F applied upon the column indicates the complete
removal of the air, after which it remains stationary. The gauge will then indicate
a pressure of 12 to 15 millimetres of mercury. As this moment, by means of the
cock G, the communication of the condenser with the pump is closed, which after
this only works to keep the interior of the apparatus free from air.
Then the refrigerating agent contained in the apparatus C effects the condensation
of the vapours.
It is preferable to employ as the refrigerating agent anhydrous
sulphurous acid, which is introduced into the apparatus by the pipe S. For this
purpose a suitable pump, which is not shewn in this Drawing, and which is in
connection with the pipe T, is set to work to draw out the sulphurous acid, which
entering the apparatus C in a liquid state is there evaporated by the heat which it
withdraws from the vapours coming from the column, and escapes in the form of
vapour from the pipe T, which leads it to a condenser, where it retakes a liquid
form ready to return again into the apparatus.
The alcoholic vapours thus submitted to a temperature of 15 to 20 degrees in the

page_text: apparatus Crapidly condense, and the liquid runs from the tubes into the chamber L,
whence it enters the receiver D. The pipe leading to this receiver sends out a
branch which returns to the top of the column B, and two cocks M, N, control the
two passages. By the branch leading to the column a part of the condensed liquid
returns to it to enrich the liquid which covers the shelves, and to render the
rectification more and more complete.
The liquid which runs into the receiver D should be of a certain degree of
purity and strength. The operator judges by the odour and the taste when the
time has arrived to collect the product as presenting all the required properties,
and all the products collected up to that time will be submitted to one or more
subsequent operations.
An axis having arms P, and set in motion by any convenient mechanism, may
be provided within the boiler A. to agitate the liquid, and so to hasten the operation.
As the alcoholic liquor becomes exhausted the temperature of the boiler A falls
so as to descend to +1, but vapour of pure alcohol nevertheless continues to be
disengaged, the temperature of the refrigerating agent falls in a like degree, and
the vacuum becomes more and more complete.
It is thus seen that the peculiarity of the process consists in submitting the
alcoholic liquors to distillation at a low temperature in a vacuum, such that the
alcohol enters into ebullition at a temperature commencing, say, at + 30 (as a
mean), and falls gradually to + 1. The differences between the volatility of the
empyreumatic products and that of alcohol becoming greater with the reduction of
the pressure the empyreumatic products are separated completely from the alcohol;
on the other hand water is not evaporated at the low temperature, so that there is
obtained an alcobol without any bad taste, and rising to 99 degrees. When the
operation has well commenced it is only necessary to pass through the coil in the
boiler A a current of water at the ordinary temperature, and the heat from this
will suffice to maintain the distillation for an indefinite time. Thus the operation
is carried on almost without fuel, which is replaced by the motive power consumed
by the refrigerating apparatus.
It is advisable that the column containing the shelves, the refrigerator, and the
receiver, as well as all the pipes, should be enveloped in some substances which
conducts heat badly.
Sheet 2 of the Drawings represents the whole of a manufacturing plant based
upon the principles already explained and illustrated by Sheet 1, but including
two successive apparatus. the one feeding the other, and producing successively
purer and purer products.
These apparatus work with the air removed and at progressive temperatures,
such that the first boiler only needs to be heated, the last condenser being kept at
a low temperature by the refrigerating apparatus, and the interior tensions of the
different elements resulting from the temperatures of the mixtures of vapours
following the laws of tension maxima and of affinities, so that there is but one
expenditure of heat for several rectifications.
Figure 1 is a vertical section of the entire system of apparatus. A, the first
rectifying boiler, heated by means of a coil U, receiving the exhaust steam from
the engine which works the pumps, receiving the exhaust steam from the engine
or other suitable fluid to provide the required temperature.
B, the first rectifying column.
C, C¹, condensers of the first rectification.
E, E', receivers of impure spirit appertaining to the first rectification.
D, cock on the communication between the two apparatus.
V, V', entrance and exit for the condensing water.
X, X¹, proof vessels for the gauges and for drawing samples.
F, boiler of the second rectification, with a coil Y heated by the condensing
water from the refrigerating apparatus.
G, column appertaining to the second rectification.
H, refrigerator working with anhydrous sulphurous acid.

page_text: J, small refrigerator also working with anhydrous sulphurous acid.
K, receiver for the alcohol of second quality from the second rectification.
L, receiver for the alcohol of first quality from the second rectification.
Z, proof vessel for gauge and drawing samples.
M, pump of the refrigerating apparatus worked by any convenient motor.
N, the condenser for the anhydrous sulphurous acid of the refrigerating
apparatus.
O, double action pneumatic apparatus.
Figure 2, detail to a larger scale of the shelves for the columns, and showing
improvements upon those represented on Sheet 1.
S is the side of the column.
P, P', shelves with a rising tube in the centre covered by a bell R, R', the bells
are pierced with holes where they meet the platform.
The liquid returning from the condenser to feed the shelves, and which is called
the "retrograding liquid," covers the shelves and runs off by the overflows T, T',
whilst the ascending vapours pass by the central passages into the interior of the
bells, and then issue by the apertures formed in them. A partition in perforated
metal or wire cloth closely woven, cover the surface of the shelf above the level of
the liquid; it causes the vapours which rise beneath it to become divided into very
small bubbles, in order to pass through it, and this renders the rectification con-
siderably more active.
The double cylinder pneumatic apparatus O in the first place produces a vacuum
in the apparatus with which it is connected by the system of pipes shown, or the
like.
The first rectifying boiler A receives the crude liquors or raw materials and
raises their temperature by the circulation within the coil U, the first rectification
takes place in the column B, and the vapours which escape pass into the con-
densers C, C, which are cooled by a current of water. The condeuser C, which is
the least cold, furnishes the retrograding liquid to the column B. The condenser C'',
which only receives the vapours which have escaped the condenser C, provides the
liquor for the second rectification.
At the outset of the operation the imperfect products of the first rectification are
directed into one or both of the receivers E, E', the proof vessels X, X¹, are measures
placed in the course of the liquors coming from the condensers to enable the amount
of the yield to be appreciated; they are furnished with special cocks by which
samples can be drawn off in spite of the difference of internal and external pressure.
The upper part of these apparatus is a glass bell through which the liquid within
can be seen, A float within indicates the specific gravity of the condensed
liquid.
The second rectifying boiler F receives the liquid which has been already purified
by the first rectification, it enters by the cock D. The coil of the boiler F is
supplied with the water coming from the condenser of the refrigerating apparatus,
of which the temperature is more than sufficient for the second vaporization. The
vapours which escape from it are rectified in the column G, which is constructed
like B, a small refrigerator J placed at the top effects the first condensation, then
the remainder of the vapour is finally condensed in the large refrigerator of the
refrigerating machine.
The resulting liquor is first directed into the receiver K which receives the
alcohols below first quality.
The pump of the refrigerating apparatus is shown at M, the condenser for the
refrigerating agent returns constantly to the refrigerator in a liquid state the vapour
which has been drawn from it by the pump. This condenser is cooled by a current
of water which passes afterwards into the second boiler.
The operation may be conducted on this basis with a grouping of two or of
several apparatus, but the arrangements described and represented to a scale of one
fiftieth give an excellent result, and are capable of rectifying 60 hectolitres of
alcohol in 24 hours.

page_text: I do not claim here the means for refrigerating, which may be any convenient
means, although I give the preference to the use of anhydrous sulphurous acid, but
I claim as my Invention the object of the present Patent,-
First. The rectifying process substantially as above described, in which advantage
is taken of the fact that the differences between the volatility of the empyreumatic
products in the mixed liquids, and that of alcohol increase with the reduction of
the pressure. This process being practised under the sole influence of maxima
tensions of the mixture of fluids in the manner described yields with a very small
expenditure of fuel alcohol of good taste, and rising even to 99 degrees.
Second. The system of apparatus substantially as described and represented by
on Sheets 1 and 2 of the Drawings for the rectification of alcohol, and for the
methodical separation of mixed liquids.
In witness whereof, I, the said Sydney Pitt, have hereunto set my hand and
seal, this Thirteenth day of June, in the year of our Lord One thousand
eight hundred and eighty one.
SYDNEY PITT. (L.S.)