IMPROVEMENTS IN AND APPARATUS FOR THE PRODUCTION OF A VACUUM IN THE EVAPORATION OR REFRIGERATION OF LIQUIDS
Year: 1884

page_text: I, GUSTAV HAMBRUCH, Engineer, of 21 Behrenstrasse, Berlin, Prussia, German
Empire, do hereby declare the nature of my said invention for "IMPROVEMENTS
IN AND APPARATUS FOR THE PRODUCTION OF A VACUUM IN THE EVAPORATION OR
REFRIGERATION OF LIQUIDS," to be as follows:-
In the process of creating a vacuum by withdrawing the air, it has hitherto been
customary to assist the formation of the vacuum by bringing the air, aspirated by
the pump, in contact with substances which absorb water such for instance as
sulphuric acid for the purpose of effecting an absorption of the watery vapour.
In spite of this assistance it is necessary, for the attainment of a high degree of
rarefaction in the atmosphere of the vessel under operation, to employ two pumps
working together. This complicates the apparatus and this drawback is not
materially improved by replacing one or both air pumps, as has already been
proposed by suction apparatus or aspirator driven by water or by steam.
Now by my invention I attain increased efficiency and simplicity in the process
of producing a vacuum by rarefaction and absorption of the air by the use of a
liquid which absorbs watery vapour for the purpose of actuating an aspirator.
A suction apparatus or aspirator operated in this manner combines in itself the
functions of an absorbing apparatus and an air pump, so that an apparatus working
on this principle is much simpler than those hitherto employed.
A further advantage of this process consists in the fact that the hygroscopic
liquid in the aspirator effects a more complete absorption of the watery vapour,
disengaged in quantity upon the formation of a vacuum, than with the usual
agitator arrangement.
The efficiency of the aspirator may be increased, by giving the jets a shape
calculated to produce wide flat surfaces of liquid, by making their orifices in the
form of narrow slits. The ordinary pattern of aspirator apparatus gives however
very good results, it having been found for instance, that such an apparatus worked
by my process produced almost perfect vacuum in a vessel which required at least
half an hour to attain the same degree of exhaustion with the air pump and
absorption apparatus previously in use. The working of the absorbing and
exhausting apparatus or aspirator in accordance with my process consists in
Price G21

page_text: principle in passing the hygroscopic liquid through the aspirator under adequate
pressure, and the connection of the suction pipe with the vessel which is to be
exhausted.
I prefer to obtain this pressure by placing a reservoir at the requisite height
above the aspirator, to supply the same, into which reservoir the liquid after
passing through the apparatus is continuously returned by means of a pump. In
the course of this circulation the liquid is preferably cooled to remove the heat
acquired in its passage through the aspirator. I have found in practice that no
material reduction in the efficiency of the apparatus takes place, until the
hygroscopic liquid, has absorbed 50 per cent of water, it is nevertheless easy to
maintain the liquid at a uniformn density by withdrawing a certain proportion of
weak liquor and replacing it by concentrated liquor, continuously or intermittently.
As suitable liquids for my process, I name sulphuric acid, solution of caustic soda
or other concentrated solutions of the caustic alkalies, or of hygroscopic salts of the
alkaline earths, but it is obvious that all liquids are available which readily absorb
watery vapour, or which enter into chemical combination with it.
Where a series of aspirators are at work, one refrigerating and concentrating
plant may be arranged to regenerate the liquor for them all.
In place of the ducts with narrow slit orifices, I may make use of a number of
small orifices or other device so as to produce either a thin broad jet, or a number
of small jets.
In the foregoing description my invention is explained with especial reference to
its use for vacuum pans for the evaporation of liquids at reduced pressure, it is
however obviously also applicable to apparatuses for refrigerating liquids for the
production of ice or of cold air and for other similar purposes.
:
WM P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool,
Patent Agents for the Applicant.

page_text: "
"3
I, GUSTAV HAMBRUCH, 21 Behrenstrasse, Berlin, Germany, do hereby declare
the nature of my said invention for IMPROVEMENTS IN AND APPARATUS FOR THE
PRODUCTION OF A VACUUM IN THE EVAPORATION OR REFRIGERATION OF LIQUIDS
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
In the process of creating a vacuum by withdrawing the air it has hitherto been
customary to assist the formation of the vacuum by bringing the air aspirated by
the pump in contact with substances which absorb water, such for instance, as
sulphuric acid, for the purpose of effecting an absorption of the watery vapour.
In
spite of this assistance it is necessary for the attainment of a high degree of
rarefaction in the atmosphere of the vessel under operation to employ two pumps
working together. This complicates the apparatus, and this drawback is not
materially improved by replacing one or both air pumps, as has already been
proposed by suction apparatus or aspirator driven by water or by steam.
Now by my invention, I attain increased efficiency and simplicity in the process
of producing a vacuum by rarefaction and absorption of the air by the use of a
liquid, which absorbs watery vapour for the purpose of actuating an aspirator.
A suction apparatus or aspirator operated in this manner, combines in itself the
functions of an absorbing apparatus, and an air pump, so that an apparatus
working on this principle is much simpler than those hitherto employed.
.
A further advantage of this process consists in the fact that the hygroscopic
liquid in the aspirator effects a more complete absorption of the watery vapour,
disengaged in quantity upon the formation of a vacuum than with the usual.
agitator arrangement.
The efficiency of the aspirator may be increased by giving the jets a shape
calculated to produce wide flat surfaces of liquid, by making their orifices in the'
form of narrow slits. The ordinary pattern of aspirator apparatus gives however
very good results, it having been found for instance, that such an apparatus worked
by my process produced almost perfect vacuum in a vessel which required at least
half an hour to attain the same degree of exhaustion with the air pump and
absorption apparatus previously in use. The working of the absorbing and
exhausting apparatus or aspirator in accordance with my process consists in
principle in passing the hygroscopic liquid through the aspirator under adequate
pressure, and the connection of the suction pipe with the vessel which is to be
exhausted.
I prefer to obtain this pressure by placing a reservoir at the requisite height
above the aspirator to supply the same, into which reservoir the liquid after
passing through the apparatus is continuously returned by means of a pump. In
the course of this circulation the liquid is preferably cooled to remove the heat
acquired in its passage through the aspirator. I have found in practice that no
material reduction in the efficiency of the apparatus takes place, until the
bygroscopic liquid has absorbed 50 per cent of water, it is nevertheless easy to
J
-

page_text: maintain the liquid at a uniform density by withdrawing a certain proportion of
weak liquor, and replacing it by concentrated liquor, continuously or intermittently.
As suitable liquids for my process I name sulphuric acid, solution of caustic soda or
other concentrated solutions of the caustic alkalies, or of hygroscopic salts of the
alkaline earths, but it is obvious that all liquids are available which readily absorb
watery vapour or which enter into chemical combination with it.
An arrangement of the apparatus is shown in the accompanying drawing in
which:
Figure 1 shows a plan of the same.
The aspirator A is connected by flange a with the space from which the air is to
be exhausted, and is supplied by aid of pipe b from the reservoir B with the
hygroscopic liquid. The aspirator A absorbs air, gases, etcetera, from the space
from which the same is to be exhausted and effects at the same time the absorption
of the watery vapour. The liquid flowing out of the aspirator A is either returned
by aid of pump P direct to the reservoir B or collected in another reservoir C from
whence it is passed to the receiver B through pipe D by aid of a pump.
Where a series of aspirators are at work one refrigerating and concentrating
plant may be arranged to regenerate the liquor for them all.
In place of the ducts with narrow slit orifices, I may make use of a number of
small orifices or other device, so as to produce either a thin broad jet, or a
number of small jets.
Figure 2 is a cross section through a mechanism with two narrow slits c c.
Figure 3 a cross section of an apparatus composed of a number of small ducts d.
It is evident that the linear orifices may be made circular or polygonal in form, as
well as the separate orifices.
Figures 4 and 5 show an aspirator with circular orifice in cross and longitudinal
section. In Figure 5 the arrows show the direction taken by the vapour drawn in
This vapour reaches the outer as well as the inner sides of the cylinder
containing the liquid.
at a.
In the foregoing description my invention is explained with especial reference
to its use for vacuum pans for the evaporation of liquids at reduced pressure, it
is however obviously also applicable to apparatuses for refrigerating liquids, for
the production of ice or of cold air, and for other similar purposes.
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
The above described improvement in the production and maintenance of a
vacuum in a closed vessel, which consists in actuating the aspirating apparatus
connected therewith by means of a hygroscopic fluid, substantially as described
and shown in the annexed drawings.
400x
WP. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, and
323, High Holborn, London,
Patent Agents for the Applicant.