Improved Methods of and Apparatus for Cooling and Evaporating.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improved Methods of and Apparatus for Cooling and Evaporating.
I, JAMES BINGHAM ALLIOTT, of Bloomsgrove Works, Nottingham, in the County
of Nottingham, Engineer, do hereby declare the nature of this invention to be as
follows:-
It is a matter of common knowledge that a liquid admitted into a chamber or
vessel in which a more or less perfect Vacuum is maintained will if and so long as
the temperature of such liquid is above its boiling point in the particular degree
of vacuum to which it is for the time being subjected, give off vapour and thus part
with heat.
With however one or two not very important exceptions, this method of cooling
has not so far as I know been made use of industrially because of the difficulty of
completing the cooling down to the required temperature with readily available
condensing liquid and degrees of Vacuum.
Now according to my invention liquid to be cooled is treated successively in two
or more Vacuum vessels provided with Condensers Vacuum Pumps and other
accessories in such a way that the cooling of the liquid is effected in stages, and
liquid previously deprived of air is employed for condensing the vapour given off
in the last Vacuum vessel. In some cases the greater part of the cooling may be
effected in the first Vacuuin Vessel while the second if there be only two may be
employed only to effect that portion of the cooling which cannot readily be effected
when a single vacuum vessel only is employed. in connection with the last of these.
vacuuin vessels I provide an apparatus wherein the condensing liquid to be used for
condensing the vapour given off by the liquid being cooled in the said vacuum vessel
has air extracted from it by exposure to a Vacuum, so that the condensing water
enters the Condenser of the said last Vacuum apparatus almost or entirely deprived
of air.
I sometimes also arrange the vacuum pump of the last vacuum vessel to discharge
into the preceding vacuum vessel or some other part of the apparatus,—it may be
into the vacuum pump connected therewith so that the vacuum pump of the last
vacuuin vessel instead of having to discharge against the full atmospheric pressure
shall only have to discharge against a very much lower pressure.
In some instances the liquid which has been used for condensing the vapour from
the last vacuum vessel may afterwards be used either alone, or in conjunction with
a further supply of condensing liquid for condensing the vapour given off in the
preceding vacuum vessel and in such case the liquid from the last vacuum.vessel
may be used in a preliminary condenser and the fresh condensing liquid in
a supplementary condenser.
In some instances the required liquid for condensing the vapour given off in the
first vacuum vessel or in another or it may be in all may be deprived of air in the
way already described before being used.

page_text: Sometimes in order to reduce the temperature of the liquid being cooled further
than is practicable with mere water I provide a sulphuric acid arrangement for
absorbing vapour on its way to the vacuum pump, it may be as supplementary to the
condensing water or alone. In such cases the sulphuric acid when diluted to a certain
extent will be removed and replaced by strong acid and the diluted acid will be
reconcentrated.
In other cases, where the liquid being cooled is a solution, the solution may be
made of a strength greater than is required for use, or may be concentrated by
evaporation to such greater strength, and then when this strong solution has been
cooled as described, it may be further reduced in temperature by the addition of
such a quantity of cold liquid as is needed to bring it to the strength actually
required.
In the
In some cases the condensing liquid made use of to condense the vapour given off
in the last vacuum vessel may be deprived of air by means of a vacuum produced by
the vacuum pump of the preceding or an earlier vacuum vessel of a series.
foregoing description of the nature of my invention the expression "the last'
vacuum vessel is intended to apply to the second vacuum vessel where only two are
used, in which case the expression "the preceding vacuum vessel applies to the
first, whereas if there be more than two the "preceding" vacuum vessel will be the
last but one of the series-and its relationship to the one that precedes it as respects
condensing liquid and discharge from its vacuum pump will resemble the relationship
as set forth between the last and the last but one-and so on.
"
As will be evident liquids can be boiled at low temperatures in apparatus such as
above described if slightly modified, the vacuum vessels being then provided with
suitable appliances such as steam coils for heating the liquid and so making up the
heat carried away in the vapour.
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I, JAMES BINGHAM ALLIOTT, of Bloomsgrove Works, Nottingham, in the County of
Nottingham, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be perforined to be particularly described and ascertained in
and by the following statement:-
It is a matter of common knowledge that a liquid admitted into a chamber or vessel
in which a more or less perfect vacuum is maintained will if and so long as the
temperature of such liquid is above its boiling point in the particular degree of
vacuum to which it is for the time being subjected, give off vapour and thus part
with heat.
With however one or two not very important exceptions, this method of cooling has
not so far as I know been inade use of industrially because of the difficulty of
of completing the cooling down to the required temperature with readily available
condensing liquid and degrees of vacuum.
Now according to my invention liquid to be cooled is treated successively in two or
more Vacuum vessels provided with Condensers, Vacuum pumps and other accessories
in such a way that the cooling of the liquid is effected in stages, and liquid previously
deprived of air is employed for condensing the vapour given off in the last vacuum

page_text: vessel. In some cases the greater part of the cooling may be effected in the first
vacuum vessel while the second, if there be only two, may be employed only to effect
that portion of the cooling which cannot readily be effected when a single vacuum
vessel only is employed. In connection with the last of these vacuum vessels I
provide an apparatus wherein the condensing liquid to be used for condensing the
the vapour given off by the liquid being cooled in the said vacuum vessel has air
extracted from it by exposure to a vacuum as described in the specification of another
application for Letters Patent filed by ine of even date herewith No. 3482, so that the
condensing water enters the condenser of the said last vacuum apparatus almost or
entirely deprived of air.
The accompanying illustrative drawing shows diagrammatically one arrangement of
apparatus suitable for carrying out my present invention.
1 and 2 are two vacuum vessels in which evaporation and consequent cooling of
liquid is effected by maintaining in them a more or less perfect vacuum, these vessels,
which are hereinafter respectively called the first vacuum vessel and the last vacuum
vessel, being suitable connected together as by a pipe with valve (not shown) and so
arranged that liquid that has been partly cooled by evaporation in one of them can
be run off into the next wherein further cooling by evaporation is effected, the cooling
being thus effected in stages. 3 is an air pump for producing a partial vacuum in
the vacuum vessel 1 and 4 is a jet condensing arrangement which is in communication
with the first vacuum vessel 1 and with the air pump 3 and to which condensing
liquid for example water is supplied from a suitable source through a pipe 5. 6 is
the vacuum pump for the last vacuum vessel 2 and 7 is a jet condensing
arrangement that is in communication with the said vacuum vessel 2 and with its air
pump 6.
The condensing liquid for example water used in this last condensing
arrangement 7 is supplied by a pipe 8 from a separate vacuum vessel 9 wherein a
vacuum is produced by a vacuum pump 10 so that water fed to such vacuum vessel 9 by
a pipe 11 will be deprived of air or other gas or gases it may contain before it enters
the jet condenser 7.
By effecting the condensation of the vapour coming from vacuum vessels by means
of a liquid such as water that is brought directly into contact with such vapour and
from which air has been previously extracted as set forth, a more efficient condensation
of the vapour will be attained with water at a given temperature than has heretofore
been usual without liability of impairing the degree of vacuum produced in the
vacuum vessels by the vacuum pump connected therewith. By this means the
vacuum produced in the last vacuum vessel 2 by the air pump 6 will not be materially
impaired by the condensing water that is fed into the condenser 7 and brought into
direct contact with the vapour escaping from the said vacuum vessel, the result being
that the final cooling of the liquid treated in the last vacuum vessel can be carried to
a lower degree than would otherwise be the case when using condensing water of the
same temperature and an air pump of the same power as in the example taken. The
supply of condensing water to and from the separate vacuum vessel 9 should be so
controlled and carried out as described for example in my said other specification of
even date herewith, that the water supply pipe 8 will be always full of water and that
air or other gas or gases will be readily removed therefrom. 3ª 6" and 10" are the
discharge pipes of the air pumps 3, 6 and 10 respectively; they may each
discharge direct into the external atinosphere as is shown in the case of the pipes
3 and 10ª.
I sometimes arrange the vacuum pump 6 of the last vacuum vessel 2 to discharge
into the preceding vacuum vessel 1 or some other part of the apparatus, it may be
into the vacuum pump 3 connected therewith, or, as in the arrangement shown in the
drawing, into the jet condenser 4 the interior of which is in communication with the
interior of the vacuum vessel 1 and its air pump 3. By this means the vacuum pump
6 of the last vacuum vessel instead of having to discharge against the full atmospheric
pressure will only have to discharge against a very much lower pressure, thus enabling
the said pump to produce a much better vacuum in the last vacuum vessel and

page_text: consequently a greater cooling of the liquid treated therein. In this case the pump
discharge pipe 6° and the water supply pipe 5 constitute one and the same pipe.
In some instances the liquid which has been used for condensing the vapour from
the last vacuum vessel 2 may afterwards be used either alone as in the case just
described in which the vacuum pump 6 discharges into the condenser 4 of the
preceding vacuum vessel 1, or in conjunction with a further supply of condensing
liquid for condensing the vapour given off in the preceding vacuum vessel 1 and in
such case the liquid from the last vacuuin vessel may be used in a preliminary
condenser and the fresh condensing liquid in a supplementary condenser. This is
the arrangement shown in the drawing, 4 being the preliminary condenser and 4"
the supplementary condenser which is connected to 4" by the pipe 4b and also to the
pipe 4 that connects the vacuum pump 3 with the bottom of the condenser 4.
this case the pipe 4° should be provided with a bent portion or trap 4d that will hold
sufficient water to act as a seal and ensure that the vapour coming from the vacuum
vessel 1 shall after being treated in the preliminary condenser 4 pass to the
pump 3 by way of the pipe 4b and supplementary condenser 4ª 5ª is a water
supply pipe for the supplementary condenser 4ª. This pipe is preferably connected
to the supply pipe 8 of the separate vacuum vessel 9 so that the condensing
water condenser 4ª will enter the supplementary condenser almost or entirely deprived
of air.
In
In some instances the required liquid for condensing the vapour given off in the
first vacuum vessel or in another or it may be in all may be deprived of air in the
way already described before being used.
Sometimes in order to reduce the temperature of the liquid being cooled further
than is practicable with mere water, I provide a sulphuric acid arrangement for
absorbing vapour on its way to the vacuum pump, it may be as supplementary to the
condensing water or alone.
In the former case concentrated sulphuric acid may be placed in shallow horizontal
trays 12 arranged one above another and so as to extend alternately from opposite
sides of a chamber 13 arranged as shown in dotted lines between the outlet of one of
the jet condensers for example 7 and the inlet of the corresponding vacuum pump
say 6 so that the vapour after being subjected to a condensing action in the condenser
and whilst on its way to the pump, will be caused to flow in a zig-zag course over the
sulphuric acid by which part of it will be absorbed. When sulphuric acid is alone
used for condensing or absorbing vapour passing from one or each of the vacuuin
vessels to the corresponding pump, the sulphuric acid chamber would take the place
of the corresponding jet condenser, and the separate vacuum vessel 9 and vacuum
pump 10 be dispensed with or used only for depriving of air water used in one or
more of the preceding vacuum vessels, not provided with a sulphuric acid chamber.
Such a chamber may, as in the example shown, be advantageously used in connection
with the last vacuum vessel 2 and its condenser 7 for effecting the final reduction
of temperature of the liquid treated in such vessel.
The sulphuric acid when diluted to a certain extent will be removed and
replaced by strong acid and the diluted acid will be reconcentrated or used for
other purpose.
In other cases, where the liquid being cooled is a solution, the solution may be
made of a strength greater than is required for use, or may be concentrated by
evaporation to such greater strength, and then when this strong solution has been
cooled as herein before described, it may be further reduced in temperature by the
addition of such a quantity of cold liquid, for example water, as is needed to bring
it to the strength actually required.
In some cases the condensing liquid made use of to condense the vapour given
off in the last vacuum vessel 2 may be deprived of air by means of a vacuum produced
by the vacuum pump of the preceding or an earlier vacuum vessel of a series.
In the drawing 14 shows in dotted lines, a pipe connecting the separate vacuum
vessel 9 with the vacuum pump 3 of the vacuum vessel 1. In all cases, the

page_text: degree of vacuum produced by the respective vacuum pumps and the arrangement
of the separate vacuum vessel 9 should of course be such that condensing, water
will readily flow from such vessel to the condenser or condensers to which it is
connected.
In the foregoing description of the manner of carrying out my invention the
expression "the last "
vacuum vessel is intended to apply to the second vacuum
vessel 2 where only two are used, as in the example illustrated in which case the
expression "the preceding" vacuum vessel applies to the first, whereas if there be
more than two, the "preceding" vacuum vessel will be the last but one of the
series and its relationship to the one that precedes it as respects condensing liquid
and discharge from its vacuum pump will resemble the relationship as set forth
between the last and the last but one-and so on.
.As will be evident liquids can be boiled at low temperatures in apparatus such
as above described if slightly modified, the vacuum vessels being then provided
with suitable appliances such as steam coils for heating the liquid and so making
up the heat carried away in the vapour.
Having now particularly described and ascertained the nature of the said invention
and in what manner the same is to be performed I declare that what I claim is :-
1. In the cooling of liquid by evaporation, treating the liquid successively in two
or more vacuum vessels working in conjunction with vacuum pumps and condensers
in such a way that the cooling of the liquid is effected in stages, liquid previously
deprived of air being employed for condensing the vapour given off in the last
vacuum vessel, as set forth.
2. In the cooling of liquid by evaporation, treating the liquid successively in two or
more vacuum vessels working in conjunction with vacuum pumps in such a way that
the cooling is effected in stages, vapour given off from the liquid treated being
condensed either by strong sulphuric acid alone, or in conjunction with condensing
liquid as set forth.
3. Effecting the cooling of a solution by making the solution originally of a greater
strength than is required for use, cooling such solution in stages by evaporation in
vacuum vessels according to claim 1 or to claim 2, and afterwards further reducing
the temperature of the solution by the addition to such solution of such a quantity of
a colder liquid as is needed to bring it to the strength and temperature actually
required, as set forth.
4. For carrying out the method of cooling referred to in claim 1 apparatus
comprising two or more vacuum vessels provided with vacuum pumps and condensers
and connected together so that the cooling of the liquid treated can be effected in
stages, and a vessel connected to the condenser of the last vacuum vessel and wherein
the condensing liquid to be used for condensing the vapour given off by the liquid
being cooled in such vessel has air extracted from it by exposure to a vacuum so that
the condensing water will enter the said condenser alinost or entirely deprived of air
or other absorbed gas or gases substantially as herein described.
5. Apparatus of the kind specified in the preceding claim wherein the vacuum
pump of the last vacuum vessel is arranged to discharge into a preceding vacuum
vessel or some other part of the apparatus in which a partial vacuum is maintained,
substantially as herein. described for the purpose specified.
6. Apparatus of the kind specified in claim 3 so constructed and arranged that
liquid that has been used for condensing vapour from the last vacuum vessel is used
in conjunction with a further supply of condensing liquid for condensing the vapour
given off in the preceding vacuum vessel, substantially as herein described.
7. The modified construction of the apparatus specified in claim 3 wherein one or
more sulphuric acid arrangements are used in conjunction with or in lieu of the jet
condensing arrangements for condensing the vapour coming from the liquid being
treated in the vacuum vessels, substantially as herein described.
8. Apparatus for cooling and evaporating constructed arranged and operating

page_text: substantially as hereinbefore described with reference to and shown in the accompany-
ing illustrative drawing.
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