IMPROVEMENTS IN AND RELATING TO VACUUM-PANS
Year: 1881

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
"IMPROVEMENTS IN AND RELATING TO VACUUM-PANS." A communication
from abroad by Christian Wahl, of Chicago, Illinois, United States of
America.
COMPLETE SPECIFICATION filed by the said William Robert Lake at the
Office of the Commissioners of Patents on the 6th October 1881.
"
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. IMPROVEMENTS IN AND RELATING TO VACUUM-
A communication from abroad by Christian Wahl, of Chicago, Illinois,
United States of America.
PANS.
The main object of this Invention is to improve the construction and operation
of vacuum-pans or apparatus used for evaporating liquids or liquid solutions by
heat, and the said Invention partly consists in providing the liquid pan with a
scroll or extended channel having a sufficient length to reduce the liquid or material
passing through to the desired consistency before it escapes; this scroll or channel
moreover is so formed that the said liquid or material will have its parts kept
separate or uncommingled in its passage through the pan, or has the divisions or
walls high enough to prevent the fresher parts from mingling with the partly or
fully condensed parts of the stream flowing through. The said Invention also
consists in an improved method of applying steam and in the means for disposing
of the treated liquid, the vacuum-pan or evaporating apparatus being designed and
arranged for continuous operation.
The said Invention is illustrated in the accompanying Drawing, in which
Figure 1 is a vertical section of my improved apparatus, and
Figure 2 is a plan or top view of the liquid pan drawn to an enlarged
scale.
Figures 3 and 3ª represent in section modified constructions of the bottoms of
the channels.

page_text: Figure 4 is a side clevation of the apparatus shewing a pump for drawing off
the condensed liquid in connection therewith, and
Figure 5 is an elevation shewing receivers for the evaporated or treated liquid
arranged in combination with the outlet or discharge pipe.
Like letters indicate the same parts throughout the Drawing.
A, B, indicate the exterior shell or casing, the lower half or section of which-
also constitutes a steam-jacket; C is the liquid pan; D, a trap or receiver; and E
is a pump; F, F, are alternating receivers; a is the orifice to which the exhausting
pump or apparatus is applied; b is the feed-tube or opening; c is the steam-inlet-
pipe and coil resting in the bottom of the liquid-channel, and d is an outlet or
steam-escape-pipe; c is the liquid channel, and the lower or central portion of
the said channel for the condensed material or liquid; 9,g, represent holes through
the flanges to permit the parts A, B, C, to be bolted or secured together; is the
steam-inlet-pipe to the jacket B, and i is an exhaust or blow-off pipe for the said
steam-jacket is a tube or pipe for conducting the finished or condensed material
from the pan; is an overflow pipe for the trap or receptacle D; L,, are horizontal
side or branch tubes for shortening the tube j, or for conducting the finished or
condensed material or liquid to a side pump, or to one or more receivers ; m, m, are
valves or cut-offs; n, n, represent vents.
The shell A, B, is preferably formed of cast iron, but it may be made of copper
or other suitable metal, and is of any suitable size or diameter necessary to
accomplish the desired result on the liquid treated. The liquid-pan C is by
preference formed of copper, but it may be made of other sheet or cast metal.
When formed of sheet metal it is preferable to make it stepped, as shown in
Figure 1, and to solder, braze, or otherwise secure the risers, which complete the
channel to the inside, so that any imperfection of workmanship will not be subjected
to steam-pressure and vacuum. The risers form in the liquid pan a continuous
circular or scroll-shaped channel o from the feeding pipe or opening b to the lower
end of the pan at f. The pitch of this channel e will depend upon the diameter, the
number of turns, and the depth of the liquid pan. The latter is formed with a
flange extending outward between the flanges of the shell; by these flanges the
sections are united. This construction forms a complete partition between the
upper and lower sections of the shell, so that the upper part of the device can be
used as a vacuum-chamber and the lower part as a steam-jacket.
For increasing the heating surface or applying steam at a higher heat and
pressure than would be proper with a steam-jacket I place in the channel e one or
more coils of steam pipe c. These coils may be arranged to cover the bottom of
the channel, or the said bottom may be made V-shaped, as shewn in Figure 3º, so
that a smaller stream or less flow of the material will be required to cover the
steam-coil, and for a very thin or shallow stream or flow, instead of using steam-
coils formed of pipes the bottom of the channel may be formed as shewn at c¹ in
Figure 3.
For disposing of the treated or finished liquid when the building or premises are
of a convenient height the easiest and simplest way is to run the outlet-pipe j
down about twenty eight feet into an open trap or receiver D containing a sufficient
height of the material above the lower end of the said pipe to form a seal to
prevent the air from rising through it. This receiver D is provided with the
overflow-spout k, by which the material or condensed liquid is directed into any
suitable vessel. When the apparatus cannot conveniently be arranged at such a
height for this operation the condensed liquid may be removed by a pump E or
may be admitted into receivers F attached to branch pipes ; these pipes are
provided with cut-off stops or valves m, so arranged that either receiver may be
cut off and emptied while the other is in use. The contents of these receivers may
be drawn off by providing them with spigots and vents n. The coil c and the
steam jacket are provided with ordinary safety-valves, steam-traps, and other
usual appliances.
The feed-tube b leads from any suitable feeding receptacle and is provided with

page_text: a stop or cut-off valve, so that the flow of the thin liquid through the said tube
may be regulated or stopped. The shell A may be provided with one or more
glazed inspection-holes, and the exhausting apparatus for forming and maintaining
the vacuum in the pan may be of any of the known forms used in connection with
vacuum-pans. This apparatus will be found very efficient and useful in reducing
or condensing milk, saccharine juices, gelatinous liquors, glucose, beer, bark-extracts,
gas waters, and for similar purposes.
I have shown and described my improved apparatus as circular and somewhat
globular in form, but this form is not essential, as it may be made square or of
other angular form and the discharge may be at one side or corner instead of at
the centre.
It is evident that steam may be admitted to the coil through the pipe & and
be blown off at the pipe c, and it will improve the operation of the scroll or
channel to make it of a gradually diminishing width from the upper or outer end
to the lower or discharging end, so that a uniform depth of liquid will be maintained
from one end of the said channel to the other.
I am aware that vacuum-pans with and without steam jackets have been
heretofore used for reducing or condensing liquids, but in these pans there is no
channel and no separation of the parts composing the liquid to be treated; therefore
the work of condensing requires a long time, and during this time the liquid is
exposed to the more or less deteriorating influence of the heat, and the liquid being
treated in masses or batches the mass remains in the pan until the whole is reduced
to the required consistency, and owing to the great depth or height of the mass
and its increasing density as it approaches the required degree of condensation it
becomes difficult for the steam, gas, or air-bubbles to rise or escape, and if they are
formed rapidly they are liable to lift or foam the liquid, so that it will boil over,
losses of considerable quantities of liquid being frequent from this cause.
By the employment of my improved apparatus these effects and disadvantages
are overcome, as the liquids are not treated in mass but flow through the apparatus
in a well defined, thin or shallow stream, which permits of an easy and free escape
for all of the vapors or gases, however rapidly they may be formed; moreover, no
overrunner is required for catching escaping liquids and the presence of an
attendant is not required. The amount or degree of condensation can be regulated
by the feed, as a heavy or nearly full stream will pass out with less condensation
than a shallow or lighter one, and the inflow or feed can bo regulated or adjusted
-by a valve or cock in the feed-tube.
The great length of time which the liquid is required to remain in the old style
of pans in order to attain the proper degree of concentration not only imparts a
darker color to those liquids but often changes their nature, as, for instance, when
sugar is subjected to treatment for a length of time in these pans crystalline syrups
are transformed into fructose or glucose; these defects, however, are completely
avoided in my improved pan for the reason that the liquid does not remain therein
for any great length of time but passes through it in a few minutes, during which
passage the concentration takes place.
This apparatus can also be successfully used for "drying" lard or taking out of
it the water which gives it a tendency to sour, and by operating the device
without steam in the jacket or coil, or with cold water in place of steam, it will
be found useful for cooling beer or other liquid, as by passing the latter by the
channel e through the vacuum the heat of the liquid is rapidly and greatly reduced
or completely abstracted.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I claim,
First. The liquid-pan having the continuous descending channel e in combination
with the shell A forming a vacuum-chainber, substantially as above set forth and
for the purposes specified.
Second. The liquid-pan having the continuous descending channel or groove e,

page_text: in combination with the shell A and the steam-jacket, substantially as above set
forth and for the purpose specified.
Third. In a continuously-operating vacuum-pan, the continuous and descending
channel e in combination with the steam coil or passage c, substantially as above
set forth and for the purpose specified.
Fourth. In a continuously-operating vacuum-pan, the liquid-pan having the
channel e and coil c in combination with the jacket B, substantially as above set.
forth and for the purpose specified.
Fifth. In a continuously-operating vacuum-pan, the combination of the liquid-
pan having the descending channel e with the pipe j, and a suitable trap,
receiver, or pump for taking off the treated liquids, substantially as above set
forth.
Sixth. The combination of the shell A, B, and the liquid-pan having the
channel e with the coil c, the feed-tube, and the discharge-tube, substantially as
above described.
In witness whereof, I, the said William Robert Lake, have hercunto set my
hand and seal, this sixth day of October, in the year of our Lord One
thousand eight hundred and eighty one.