Improvements in Evaporating Apparatus.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improvements in Evaporating Apparatus.
I, SAMUEL MORRIS LILLIE, of 4th and Chestnut Streets, in the City and
County of Philadelphia, State of Pennsylvania, United States of America,
Chemist, do hereby declare the nature of this invention and in what manner the
same is to be performed to be particularly described and ascertained in and by the
following statement :-
pan, or
66
My invention relates to "intransit evaporating apparatus" namely, apparatus in
which the evaporation is effected from a liquid while flowing in comparatively thin
films or sheets over the heated evaporating surfaces. It consists, as regards a single
effect," of a battery of horizontal evaporating tubes contained in an
evaporating chamber which tubes are closed at their ends fronting one end of
the chamber, and at their other extremities connect with steam supply conduits
from which their interiors are supplied with steam.
Above the evaporating tubes in the chamber is arranged a spraying or
distributing device or devices, fed by a suitable conduit with the liquid to be
evaporated, and by which the liquid is distributed over the surfaces of the
evaporating tubes and then flows downwards over the same to the floor of the
evaporating chamber. The tubes are provided with means for the escape of air or
incondensible gases that may collect in them and tend to exclude the steam and so
lessen the efficiency of the apparatus, and the evaporating chamber is provided
with proper escapes for the vapours resulting from the evaporation, and for the
concentrated liquid. In the accompanying drawings I have shown, in double
effect, apparatus constructed according to my said invention, the several figures of
the said drawings being hereinafter referred to.
Figure 1 is an end elevation of a double effect with the front plate of the
evaporating chamber of one of the effects removed so as to expose the sealed ends
of the evaporating tubes to view.
Figure 2 is a side view of the double effect with one of the pans shown in
vertical longitudinal section, i.e. parallel to the axes of the evaporating tubes.
Figure 3 is a plan of the double effect, and,
Figure 4 is a view of a modified construction of portion of the apparatus.
Referring to these figures, s, s, is a battery of horizontal tubes contained in a
chamber E, having their ends, towards one end R of the chamber, tightly sealed
save for a small perforation c in each looking towards the plate R. The other
ends of the tubes open through the opposite end plate "G" in which they are
tightly expanded and by which they are supported into a steam fed chamber S,
closed by a door D, and having a steam or vapour supply main B, and a valved
pipe which leads through suitable connections to the vacuum pumps used in
connection with the apparatus. The evaporating tubes are arranged in horizontal
rows which break spaces with each other vertically, and the two side walls have
horizontal ribs e, e, &c. which break spaces between the two side rows of tubes and
the said side walls. The liquid distributing device above the tubes consists, in the

page_text: construction shown, of a horizontal plate 4, located immediately above the tubes
and pierced by longitudinal slots, one directly over the axis of each tube of the
uppermost row. Above the slotted plate, are one or more perforated distributing
plates a, above and upon the uppermost one of which the return feed pipe A delivers
through the walls of the case. One of the side walls of the evaporating chamber E,
is formed with the passage in it which communicates below through a horizontal
narrow opening g, with the interior of the chamber E beneath the tubes, and above
through the nozzle J, to a catch-all C, from which the vapour escape H leads to a
suitable condensing apparatus.
Below the lower row of evaporating tubes the chamber E contains a corrugated
false bottom n, which touches the hollow side wall above the narrow horizontal
opening g, and extends slightly inclined downwards, to within a few inches of the
opposite wall, the corrugations extending in the same direction. From below the
false bottom, n, and from the side of the chamber E, opposite the vapour outlet g,
a discharge conduit o, leads through suitable connections to a circulating pump P,
whose discharge pipe A, which I will term "the return pipe" delivers back into
the space F, above the upper perforated plate a. In the double effect shown in the
drawings, and hereinafter described, these connections of the discharge pipe o, of
the first pan to the circulating pump P are through the second effect and its
connections; and those of the discharge opening ', of the second effect are through
the float chamber T, and connecting pipe . A conducting pipe N for the liquid
to be evaporated delivers into the return pipe A at a point i, and a pipe L for the
thickened liquid leaves the return pipe at ra point between where the feed pipe N
joins the return pipe A and the circulating pump-and leads to the tail pump I,
which is provided for drawing away the concentrated material. In the drawings
two pans, constructed as above described, are placed one above the other and
connected so as to form a double effect, the upper pan being the first effect and the
lower pan the second effect. The various parts hereinbefore referred to are
indicated in the first effect by the letters stated, and in the second effect by the
same letters primed.
The steam case S of the first effect is supplied with steam from an extraneous
source by the main B, the vapour main H of the first effect leads into the steam
chamber S¹ of the second effect, and the vapour main H' of the second effect leads
to a condenser and vacuum pumps by which a proper vacuum is maintained in the
evaporating chamber E' of the second effect. The liquid discharge pipe o of the
first effect delivers through a steam trap (that shown in the drawings consisting of
a U tube with valve u, in it) above and upon the distributing plates of the second
effect. The discharge for liquid from the evaporating chamber of the second effect
is by opening o' through the floor of the latter into the float box T from which a
connection leads to the suction port c of the circulating pump P. The float box T
contains a float having a stem the end of which is keyed on the arbor of a butterfly
valve v, located in the thin liquor pipe N, which stem extends through the side of
the box into the interior of the same. The rising and falling of the float respectively
closes and opens the butterfly valve. The return pipe A in the pump delivers into
the feeding space F of the upper effect, and also has a valve branch connection A¹
to the feed space of the second effect, permitting liquor to be returned to both effects
simultaneously if desired.
The operation of this double effect may be described as follows, it being first
supposed that all air has been exhausted from the apparatus by means of the vacuum
pump and connections, and that steam is being continuously led into the steam
chamber S of the first effect, and that the vacuum pumps and condenser are at
work maintaining the proper vacuum in the case E' of the last effect. The double
effect contains during normal working about, say, fifty gallons of liquid, which is
continuously circulated through the two effects by the circulating pump P at a rate
sufficient to keep the surfaces of the tubes thoroughly covered with films of liquid.
The liquid passes from the circulating pump by the return pipe A up into the
feeding space of the first effect, falls through the perforated plates evenly

page_text: distributed upon the slotted plate 6 below, through whose slots it flows upon the upper
surface of each of the tubes of the uppermost row, and thence flows down over the
battery of tubes, from tube to tube to the floor of the evaporating chamber,
whence it passes through the pipe o, and trap upon the distributing feed
plates of the second effect, and thence upon and down over the exterior
surfaces of the tubes of the second effect on to the floor of the evaporating
chamber of the same, and thence through the float chamber T to the circulating
pump again.
The tubes in each vertical row serve as deflecting surfaces for the liquid which
falls from the adjacent vertical rows, throwing the liquid which does not adhere to
and wet themselves back on to the tubes of the adjacent rows, and the ribs, e, on
the side walls of the evaporating cases, serve to throw back upon the tubes the
liquid which would otherwise leave them and run down the surfaces of the walls.
The thin liquid which is to be thickened is continuously fed by the feed pipe N into
the return pipe A and mixes with and thins the ascending liquid, which in flowing
down over the evaporating tubes in the two effects is thickened again. The con-
centrated circulating liquid is constantly being drawn through the discharge
pipe L at a rate regulated by the valve p in the said pipe. The steam affording
the original heat is fed to the steam chamber S of the first effect, and thence flows
into the tubes of the same. The vapours resulting from evaporation of the first
effect escape from its evaporating chamber into the vapour passage S at one side
and thence through the catch-all C and pass from the latter by the vapour pipe H
into the steam chamber S' of the second effect and thence into the tubes of the
latter. During its passage through the catch-all all particles of entrained liquid
are separated from the vapour and remain in the catch-all from which it flows by a
drain pipe j back into the chamber E. The vapours resulting from the evaporation
in the second effect escape through its catch-all C', and vapour pipe Hi to the
condenser and vacuum pumps, which are not shown in the drawings. The
regulation of the density of the concentrated material, that is, the flow of liquid
through the double effect, is effected entirely by means of the valve p, in the
discharge pipe L, the inflow of thin liquid by the feed pipe N being maintained
proportional to the outflow through the discharge pipe L by the automatic action
of the level of the liquid in the float chamber, and the float and the butterfly valve
in the feed pipe N operated by the same. Opening the valve in the discharge
pipe L permits the more rapid flow of the liquid through the apparatus, and conse-
quently diminishes the density of the finished product: closing the valve, lessens
the flow of liquid through the double effect and increases the density of the finished
product. The rate of evaporation in the double effect is varied by increasing or
diminishing the pressure of steam in the chamber S of the first effect, supposing the
vacuum to remain constant.
While in operation steam or vapour is constantly flowing into and being condensed
on the interior surfaces of the tubes while evaporation from the liquid takes place
from the exteriors of the tubes. Any air that may leak into the effects, which
must be expected to occur to a greater or less extent in all vacuum evaporating
apparatus, will collect in the tubes at their closed ends, and if not allowed to escape,
or if not occasionally exhausted would, in time, materially diminish the efficiency
of the apparatus. To permit the escape of air the closed end of each tube has the
perforation c through it by which the air which reaches the ends of the tubes
continuously passes into the surrounding evaporating chamber, and thence through
the intermediate connections to the vacuum pumps. In the case of the tubes of the
first effect of a multiple effect evaporating apparatus the tubes and evaporating
chambers of the pans between it and the vacuum pumps respectively form parts of
the said intermediate connections. In this manner the enemy, stagnant air and
incondensable gases which is met and has to be overcome in every form of multiple
effect evaporating apparatus, is easily and entirely avoided and the entire surface
of each evaporating tube made efficient. The inner and outer surfaces of the tubes
are readily cleaned. By opening the door of the steam case S the open ends of

page_text: the tube are exposed which permits their inner surfaces being cleaned by
means of a flue cleaner. The opening of the door R at the front end of the
evaporating chamber exposes the closed ends of the evaporating tubes and
the spaces between them, and permits the exterior surfaces of the tubes being
cleaned with the greatest case by means of scrapers or swabs. During this
cleaning of the exterior surfaces a circulation of water or other liquid may be
maintained over the tubes by means of the circulating pump, P, which will serve
both to assist cleaning and to wash the dirt from the chamber and effect. Opening
the door of the evaporating chamber also permits the perforated plates a, b, to be
removed and cleaned if necessary. The corrugated false bottom n, in each effect
assists in separating the thickened liquid and the vapours resulting from evaporation
first by delivering the liquid as far as possible away from the vapour outlets g,
and also by collecting the liquid into the depressions of the corrugations, from
which it flows in solid streams upon the floor of the chamber E leaving free
intermediate spaces through which the vapours may flow back under the plate
towards the vapour outlet f. I omitted to state in the preceding that the water of
condensation resulting during the working of the apparatus flows from the
evaporating tubes s back into the chamber S, and thence away by the drain
pipe m.
Instead of the perforations, c, in the closed ends of the evaporating tubes, for
permitting the escape of air and incondensable gases from the interiors of the tubes
the construction illustrated in Figure 4 of the drawings may be used for the
purpose. This construction consists in connecting the closed ends of a number of
the evaporating tubes together, to form a nest of tubes, by small connecting pipes
contained within the evaporating chamber and having a single escape for the air
from the pipes. Thus, in Figure 4, a number of evaporating tubes, s, representing
a row of tubes, are shown thus joined by the small air escape pipes 1, 1 &c., in
connection with a common manifold, 2, located in the evaporating chamber, which
manifold in turn opens into a cross pipe 3 (into which other similar manifolds of
other rows of tubes may open), which in turn connects with any suitable exhausting
apparatus, none shown in the figure, by which the air and incondensable gases are
drawn from the evaporating tubes; eg. the cross pipe 3 might open into the
evaporating chamber, which in combination with its connections to the condenser
and pump would in that case be the "exhausting apparatus." By thus joining the
tubes into nests, by connecting air pipes, each tube receives some support at its
free end from the other tubes of the next to which it belongs, which is an advantage
in cases where a hard and refractory scale is being cleaned from the exterior
surfaces of the tubes by means of scrapers introduced through the opened door R.
In constructing the individual effects the plate R, forming the front end of the
evaporating chamber is hung on hinges w, as a door, and also the plate D, forming
the cover of the steam case S, by hinges a for the convenience in opening.
When closed these doors are caused to make air tight bearings against the end
flanges of the case by any of the methods usually employed for the purpose in
similar constructions. When practicable the chamber E, is cast in one piece, the
perforated plates a, b, being supported in position on ledges formed on the interiors
of the walls of the chamber at the proper places. The plate G, forms at once one
end of the chamber E, and the tube plate, and with it the side walls of the steam
chamber S are formed in one piece, all as shown in the drawings. A feature of
this construction is that the tube sheet and the sealed evaporating tubes form a
distinct and separable element of the construction, and may be removed from and
replaced in position at will after loosening the fastenings which hold it in place.
In larger apparatus the tube plate proper might form but a portion of the end of the
body E of the pan, simply covering and closing an opening in the end wall through
which the battery of tubes supported in the tube plate project into the interior.
In Figures 5 to 18 inclusive are illustrated modified constructions in my inven-
tion. Figures 5 and 6 show the case of the evaporator formed of two parts
dividing along the horizontal plane 5, immediately below the distributing device of

page_text: the evaporator. When it is desired, if ever, to increase the capacity of the
evaporator the two portions of the same may be separated and a section containing
one or more rows of tubes be inserted; such a section of tubes is shown at K
Figure 8, which, in Figure 7, is shown inserted in place between the upper and lower
portions of the evaporator, whereby its evaporating surface is increased by two
rows of tubes. If it should afterwards be desired to further increase the evaporating
surface, another section K of tubes may be inserted. In Figures 5 to 9 is shown a
method of connecting the tubes together at their closed ends to form nests, which.
may be considered a modification of the construction shown in Figure 4. In
Figure 5 tubes are formed in nests of three by triangular manifolds 4; in Figure 9
they are shown joined in sets of four cach by a four branch manifold. In these
constructions the air is allowed to escape from the tubes through a perforation in
each manifold at a point where the branches unite. Various means may be employed
for permitting the escape of air from the nest of tubes different from that shown
in Figure 4 from that shown in Figure 5, and I do not limit myself to any particular
devices for the purpose.
In Figures 11, 12, 13 and 14 the evaporator is shown having a cylindrical case
instead of a rectangular one. In these constructions the circular case is shown
divided along a horizontal plane at 5 to permit of the introduction of sections of tubes
whenever it may be desired to add to the evaporating surface of the apparatus. The
distribution of the liquid over the tubes in these cylindrical constructions is effected
by distributing devices, as the perforated plate a and slotted plate located
above the middle portion of the tubes in combination, in Figure 12, with side
deflecting plates, 9, 9, which direct an excess of liquor falling through the outside
slots of the plate B, which slots are made broader than the others, upon the
vertical rows of the tubes which are not below the slotted plate. In Figure 14
the slotted plate B is a portion of the cylinder, or it may be a plate of that shape
loosely supported in the position shown. The perforated distributing plate a in
this construction is located in a chamber formed above the cylindrical case, and
the liquid to be evaporated is delivered upon it through the pipe A as in the other
constructions of the evaporator. This arrangement shown in Figure 14 permits a
more complete filling of the interior of the cylinder with tubes than is the case in
the construction shown in Figures 11, 12 and 13. The ledges 11 shown on the
upper side of the curved slotted B, Figure 14, serve to deflect the liquid which
tends to flow down over the curved surface into and through the slots, and the
similar small ribs on the under surface of the curved plate prevents the liquid
flowing through the slots from collecting upon and running along down the under
surface of the curved plate, and compels the liquid which passes through each
slot to fall down upon the tubes immediately below it. In Figures 15, 16, 17
and 18, is shown still another modified construction of my apparatus, in which the
free ends of the evaporating tubes are supported by easily removable supports,
which in Figure 15 consists of plates 6 each having holes through it corresponding
in size and distance apart to the tubes of a horizontal row, over the free ends of
which it slips and is supported by any suitable means on the side walls of the case
of the evaporator and which supports in Figure 18 consist of bais of metal bent as
shown in the figure, which are inserted one underneath each row of tubes as shown.
In the construction illustrated in Figures 15 to 17 the end of the evaporating
chamber is not formed with a door, as shown in the other figure, but instead the
chamber is made longer, so that the section E in front of the tubes may be large
enough for a man to enter, and for him to work comfortably in, to clean the tubes,
a man-hole 12 being formed in the side of the chamber to admit of entrance into
the interior E.
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
First. In an evaporator operating substantially as described, the combination of

page_text: the following elements, riz.: A horizontal evaporating chamber, a battery of hori-
zontal evaporating tubes contained in the chamber and having their ends towards
one end of the same closed and connecting at their other ends with suitable steam
supply conduits, means for delivering the liquids to be evaporated upon the
evaporating tubes in the evaporating chamber, suitable escape passages leading
from the evaporating chamber for the vapours formed and for the unevaporated liquid
and a door or removable plate closing the end of the horizontal evaporating chamber
which faces the closed ends of the evaporating tubes, the door when opened exposing
the closed ends of the evaporating tubes and the spaces between them, thus per-
mitting access to the exterior surfaces of the tubes for cleaning purposes, sub-
stantially as specified.
Second. In an evaporating pan the combination of a horizontal evaporating
chamber containing a battery of horizontal evaporating tubes, a horizontal feed
chamber above the evaporating chamber, and a door or removable plate, R, forming
a cover common both to an end of the evaporating chamber and to the same end of
the feed chamber substantially as specified.
Third. In an evaporating pan constructed and operated substantially as described,
the combination of a horizontal evaporating chamber, with a feed chamber above
the evaporating chamber and separated from it by a perforated distributing septum,
a vertical removable tube plate forming a common cover to the evaporating and
feed chambers at one end a battery of horizontal steam fed tubes in the evaporating
chamber opening through the tube plate and closed at their other ends, and a door
or removable plate forming a cover common to the evaporating and feed chambers
at the end opposite the tube plate, substantially as specified.
Fourth. In an evaporating pan, the combination of a horizontal evaporating
chamber having suitable vapour and liquid escapes, a removable vertical tube plate
covering one end of the evaporating chamber and carrying tubes projecting hori-
zontally into the evaporating chamber and which have their ends in the latter
closed, a door or removable plate closing the other end of the evaporating chamber
which when opened exposes the ends and exterior surfaces of the tubes means
for distributing the liquid to be evaporated over the exterior surfaces of the tubes,
and means for supplying steam to the interiors of the tubes, substantially as
specified.
Fifth. In an evaporating pan constructed and operating substantially as described,
the combination of evaporating tubes each closed at one end and supplied with
steam from the other end, and small air escape tubes, one leading from each tube
at or near the closed end of the same, the said air escape tubes affording means for
the continuous escape of the air or incondensable gases which collect at the closed
ends of the evaporating tubes in the interior of the latter, during the working of the
apparatus, substantially as specified.
Sixth. In an evaporating pan having a battery of horizontal evaporating tubes
contained in an evaporating chamber and opening at one end through a tube plate
to steam supply connections, and having their other ends in the evaporating chamber
closed, and means for delivering the liquid to be evaporated upon the exterior sur-
faces of the tubes all substantially as set forth, the combination with the evaporating
tubes of small pipes connecting the closed ends of the tubes to form nests of tubes,
and an air escape for each nest connecting to suitable exhausting apparatus, sub-
stantially as specified.
Seventh. In an evaporating pan having a battery of evaporating tubes arranged
in rows in an evaporating chamber and opening at one end through a tube plate to
steam supply connections, and having their other ends in the evaporating chamber
closed, and means for delivering the liquid to be evaporated upon the exterior
surfaces of the tubes all substantially as set forth, the combination with the rows
of tubes, respectively, of manifolds contained in the evaporating chamber with
intermediate connections to suitable exhausting apparatus, and small air escape
connections between each manifold and the closed ends of the tubes of its row,
substantially as specified.

page_text: Eighth. In an evaporating pan having a battery of horizontal evaporating tubes
contained in an evaporating chamber and opening at one end through a tube plate
to steam supply connections, and having their other ends in the evaporating chamber
closed, and means for delivering the liquid to be evaporated upon the exterior
surfaces of the tubes all substantially as set forth, the combination with the
evaporating tubes of small pipes connecting the closed ends of the tubes to form
nests of tubes, and perforations in the said connecting pipes to permit the escape of
air and incondensable gases from the nests of tubes into the surrounding chamber
substantially as specified.
Ninth. In an evaporator consisting of a battery of horizontal steam supplied
tubes contained in an evaporating chamber with means above the battery of tubes
for distributing the liquid to be evaporated over the exterior surfaces of the tubes ;
the formation of the evaporator of a number of horizontal sections, the upper
section containing the said distributing devices; and the remaining sections con-
taining one or more rows of tubes, the said sections being separable from each other,
so that sections of tubes may be added to, or taken from the evaporator to increase
or diminish the evaporated surface of the same substantially as specified.
Tenth. In an evaporating apparatus having an evaporating chamber containing a
battery of horizontal evaporating tubes opening through a tube plate forming one
end of the chamber to steam supply connection, and having their other ends closed
and free, the combination with the free ends of the tubes of removable supports by
which the ends of the tubes are supported, and which may be removed to permit
free access to the exterior surfaces of the tubes substantially as specified.
Eleventh. An evaporator consisting of a cylindrical battery of horizontal steam
fed evaporating tubes contained in an evaporating chamber, a distributing device
above the tubes for distributing the liquid to be evaporated upon the middle vertical
rows of tubes, means for delivering the liquid to the said distributing device, and
means for deflecting portions of the liquid so delivered over the vertical rows of
tubes on each side of the said several rows substantially as specified.
Dated this 25th day of Anril 1801
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.