Improvements in the Evaporation of Brine and other Solutions or Liquids and in Apparatus Employed therein.
Year: 1890

page_text: COMPLETE SPECIFICATION.
Improvements in the Evaporation of Brine and other Solutions or
Liquids and in Apparatus Employed therein.
A communication from abroad by CASSIUS C. PECK, of Warsaw, County of Wyoming,
State of New York, United States of America, Manufacturer.
I, JOHN CLAYTON MEWBURN of 55 and 56 Chancery Lane in the County of
Middlesex, Fellow of the Institute of Patent Agents, 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 :-
This invention relates to the evaporation of solutions or liquids in vacuum
evaporating apparatus. It is intended primarily for the evaporation of brine in the
manufacture of salt, but it may be advantageously applied to the evaporation of other
liquids. The principal features of the invention are first, placing the heating surface
which heats the liquid to be evaporated, outside of the vacnum pan, or chamber, and
by means of a pump causing a rapid circulation of the liquid under treatment between
the said heating surface and the vacuum chamber. Second, constructing the vacuum
chamber of brick, stone or concrete masonry, laid up with hydraulic cement and
covering the outside of the chamber, if the walls are not air-tight, with a thin metallic
or other equivalent air-excluding coating. Third, giving the bottom of the masonry
vacuum chamber a hopper or inverted cone form, in combination with a conveyor
communicating with the bottom of the chamber, for the purpose of delivering wherever
required outside the chamber, the solid material which collects in the bottom. Fourth
connecting two or more of such chambers together, and with a vacuum pump.or
pumps to the end that two or more uses of the primary heat may be obtained in
evaporating. Fifth, a continuous process in which the several features are-the
separation of salt from brine in apparatus so arranged that the heating surface can be
cleaned without interruption of the process of evaporation, automatically removing
salt from the evaporator, and drying the salt while conveying it to any suitable point
for bolting, storage or shipment. Sixthly, the invention includes broadly the substitu-
tion for the ordinary vacuum pan heretofore used of an apparatus in which the
following elements are combined, namely a tank open to the atmosphere for containing
the liquid to be evaporated, a vacuum chamber opening at its lower end into the said
tank and sealed by the liquid therein, and a heater arranged to impart heat to the
liquid in the tank to effect its evaporation within the said vacuum chamber. In this
connection the invention also consists in connecting with the discharge pipe of the
heating coil a means for automatically discharging the liquid of condensation, and at
the same time heating the necessary supply of feed liquid; and also in special means
for removing mechanically from each tank solid matters or precipitates as fast as they
collect, so that the evaporating process may go on continuously and without the
interruptions necessary in the case of the ordinary vacuum pan in discharging the
solid products of evaporation. Seventhly, the invention includes broadly the process
of imparting to the brine or other liquid under treatment, prior to its introduction
into the vacuum chamber, a sufficient degree of heat to effect the evaporation of the said
liquid in the said vacuum chamber, either by means of an exterior open heating tank as
set forth in the sixth feature of the invention as above or by means of an exterior closed
boiler or other form of closed heater.
The apparatus for effecting the interchange or circulation of the liquid under
treatment between the vacuum chamber and the exterior closed heating surface may
be so arranged that the liquid will flow and circulate naturally between the two, the
cooler liquid from the lower portion of the vacuum chamber flowing back to the closed
boiler or heater as the hotter liquid is received from the heater into the vacuum
chamber at a higher level.
The natural or gravity circulation above referred to will answer where the process

page_text: is, owing to the nature of the liquid under treatment, or the result sought, necessarily
or designedly slow, but where rapid evaporation is désirable, as in the case of brine
and other liquids from which crystalline precipitates are obtained, I employ a forced
circulation of the liquid between the vacuum chamber and the enclosed heating
apparatus, thereby augmenting the amount of evaporation within the vacuum chamber
and at the same time preventing or counteracting the tendency to incrustation and
securing the deposit of crystals of uniform size.
In this connection I may mention a feature of the invention which is not necessarily
dependent upon the use of the closed heating apparatus, although, shown in com
bination therewith. This consists in still further increasing the flow or motion of the
liquid within the vacuum chamber itself by causing it to assume a gyratory motion
therein, the liquid from the heater being injected into the vacuum chamber in a line
which is substantially tangential thereto. I also utilize this vortex movement just
described as imparted to the liquid within the vacuum chamber for the further
purpose of separating the crystals from the concentrated liquid when the products
of evaporation are discharged from the lower part of the vacuum chamber. This I
accomplish by ejecting the liquid carrying the crystals into a separating basin
tangentially, from which separating basin the crystals may be removed centrally.
By the use of the vortex movement as above set forth the formation of crystals
of large size is prevented, and a finer and more uniform product is obtained.
Sait is usually made by evaporating brine in shallow pans, or else in kettles with
fire underneath, or in shallow wooden tanks called " grainers" which are heated by
steam pipes; also in a few instances with steam jacketted kettles.
In all these cases the salt, as precipitated from the brine, has to be lifted out of
the evaporating apparatus by hand, placed in carts and wheeled to draining bins, in
which latter it remains at least fourteen days before being sufficiently dry to be
barrelled and shipped as common salt.
The labor involved in excavating the salt from the bins is considerable, and if it
is to be made into "dairy" or "table" salt it has to be wheeled to the drying room,
or apparatus, and delivered into it. This latter usually consists of a large horizontally
set steam or fire heated iron drum, in which the salt is tumbled, entering at one
end of the drum and passing out at the other end.
The several processes of evaporation, draining, artificial drying and handling being
conducted separately and independently involve the expenditure of much time and
labor, which I save by a continuous system which conducts the salt. through the
different required steps automatically.
I am aware that certain devices have been patented for automatically discharging
salt from evaporating apparatus, also for mechanically draining salt in centrifugal
machines, similar to those employed for draining sugar, but I am not aware that the
several steps involved in making salt as herein described have ever heretofore been
combined in such
:
manner.
The effect of locating the heating surfaces outside the evaporating apparatus and
of establishing a rapid circulation of brine as hereinbefore mentioned is to make, the
beating surface accessible at all times for cleaning, without interruption of the process
of evaporation, and also to cause the deposit of salt precipitated by evaporation to occur in
the evaporating apparatus and removed from the heating surface, so that the latter. is
not clogged and rendered inefficient by such deposit as is the case in other. kinds of
evaporating apparatus; while the rapid forced circulation of the brine maintains the
brine at nearly the same temperature in the evaporating apparatus as in the pan or
tank where it is in contact with the heating coil, and by causing the greatest possible
amount of heat to be conveyed away from the heating coil, gives to this its maximum
efficiency, and augments the amount of evaporation which can ordinarily be effected
with a given amount of heating surface.
"An important feature of the invention is the utilization of a forced current of brine
to collect the, solid products of evaporation in the evaporating apparatus and deliver
said products into a pocket or basin convenient for removal by ordinary conveying
mechanism.

page_text: Still another important feature is conveying the wet salt in such manner against
an oppositely moving current of heated air that the salt shall become dried on its
passage from the evaporating apparatus to the bolting or screening apparatus or
storage room.
In the accompanying drawings I show apparatus suitable for carrying out the
process practically, although I do not wish to confine myself to the use of any special.
form or combination of apparatus, since it is obvious that various modifications may
be made therein without deviating from the essential features of the invention.
Eigure is a vertical central section through line a-a, Figure 2, of two connected
masonry vacuum chambers set in separate open tanks and provided with exteriorly
placed heating surface, and also an additional tank for heating the liquid under
treatment on its passage to the vacuum chambers.
Figure 2 is a plan view of same, showing also the centrifugal pumps used in
circulating the liquid under treatment between the vacuum chambers and the
exteriorly located heating surface, the double acting vacuum pump, and an overflow,
tank.
Figure 3 is a vertical sectional elevation at right angles to Figures 1 and 2;
showing on a larger scale the exterior form of the vacuum chamber, and also
the arrangement of a conveyor for discharging solid matter deposited from the
chamber.
Figure 4 is a vertical central sectional elevation of apparatus embodying the various
steps in my process of making salt.
Figure 5 is a plan view of same.
Figure 6 is an elevation at right angles to Figures 4 and 5.
Figure 7 shows in vertical central section the general arrangement of a series of
evaporating reservoirs or tanks, together with the boiler used both for preliminary
heating of the feed liquid for the tanks and for furnishing steam to the heating coils
in the first evaporating tank, and for driving the air and the liquid pumps; also the
well wherein the liquid of condensation from the several tanks is collected.
Figure 8 is a central vertical section of the trap used for discharging condensed
steam from the coil in the first tank ;
Figure 9 is an enlarged cross section of the trap through plan of line x, x,
Figure 8.
Figure 10 is a plan or top view of two evaporating tanks out of a series to show
the arrangement of the combined heater and condenser coils; also showing the cylinders
of the conveyors which remove deposits from the tanks.
Figure 11 is a vertical sectional view of one of the evaporating tanks.
!
Figure 12 is a plan of apparatus in which the vacuum chamber is situated in an
exterior open liquid supply tank which is also provided with a separating basin for.
receiving the discharge from the vacuum chamber.
Figure 13 is a vertical section upon plane of line a, a, Figure 12.
Figure 14 is a plan of a modified form of apparatus in which the unevaporated
liquid is returned directly from the lower part of the vacuum chamber to tlie heater;
Figure 15 is a vertical section upon plane of line y, y, Figure 14.
In Figures 1 to 3 coil heaters B, B₁ are placed within the tanks D; D'. These
coil heaters may be of any convenient form or construction to suit the character of
the fluid in which they are placed, the essentials being that there shall be sufficient
surface to effect the desired amount of evaporation, and that where deposits or
incrustations are liable to form, the heating surface shall be so arranged as to be
accessible for cleaning.
A circulation of steam or hot liquid passes through pipe b, 61, heats coil B; and
through it the liquid contained in tank D. This liquid is forced into vacuum chamber A
by the vertically set centrifugal pump E through pipe e.
Vapor given off from the heated liquid and collecting in the top of chamber A;.
is withdrawn by vacuum pump C, being mostly condensed in coil B₁ on its passage
to the pump.
The condensation of vapor in the said coil supplies heat to the liquid in the?

page_text: tank D', and this liquid is forced into the chamber A' by the centrifugal pump E.
Vapor collecting in the top of chamber A' is removed by the vacuum pump C, and is
mostly condensed in coil B2, in tank D2, on its way to the pump.
A constant and rapid circulation of the liquid in tanks D, D is maintained between
chambers A, A¹ and heater coils B, B' by pumps E, E¹. The direction of this
circulation is shown by arrows. This rapid circulation effects two important results;
first, it maintains the liquid inside the vacuum chambers at approximately the same
temperature as that in contact with the heating coils, and second, the force of the
current flowing out from the vacuum chambers sweeps down the sloping sides of the
chambers and out through circular openings a, a into the basins or pockets d', d³ in
tanks D, D¹, the granular or other solid matters deposited from the liquid through
the process of evaporation. The deposited matter is thus brought in contact with the
conveyors F, F which are driven from any convenient source of power, and which
elevate and deliver it outside the tanks.
These conveyors may be of any convenient form of construction to suit the material
being handled, such as a chain and buckets driven by sprocket wheels, or a belt with
or without buckets attached, or a screw or worm working in a case.
Pipes ², are so connected with cylinders c, e¹ of pump C that each cylinder may
be operated as a separate pump, or the suction of both cylinders may be applied to
one pipe. Thus in the former case valve is closed and valves 8, 9 are opened, and
in the latter case valve is more or less opened and valves 68, 69 are more or less
closed in proportion to the amount of suction which it is desired to apply to each
cylinder.
The liquid to be evaporated is first received and heated in tanks D¹ and D as
required, by maintaining a suitable supply in said tanks, the supply being preferably
arranged as a gravity flow from one tank to the other, although a pump or pumps
may be used for delivering the feed liquid from tank D2 to tanks D and D. This
constitutes a double effect apparatus. The evaporation in vacuum chamber A serves
to effect the evaporation in chamber A', and heat passing from the latter chamber
with the vapor is absorbed by the feed liquid in tank D².
The height of vacuum chambers A, A corresponds with the amount of vacuum
to be maintained, being also governed by the nature of the liquid which is to be
treated. Thus when the vacuum carried is high and the liquid has a tendency to
foam, chambers or cylinders of 30 feet and upward in height will be required, while
with low vacuum, and a liquid from which vapor separates readily, 10 to 15 feet in
height will be sufficient.
The vacuum chambers are preferably constructed of some form of masonry such
hard bricks or stones laid up with hydraulic cement and coated upon one or both
surfaces of the walls (inside and out) with sand and cement.
The best form of masonry for constructing the wall is that containing a large amount
of hydraulic cement, such as concrete, carefully made with the best Portland cement,
or béton made as in forming artificial stones.
When the walls are constructed of concrete or béton, and of several inches in
thickness, a moderate vacuum can be maintained within the chamber, but when built
of bricks or stone or when intended to maintain a high vacuum with the greatest
economy, I cover the ouside of the chamber or chambers with a thin coating of some
air proof material such as thin sheet metal with soldered or other air-tight joints, the
air proof coating enveloping the whole chamber and extending below the level of the
liquid in the open tank.
The masonry walls of the vacuum chamber require in any case to be made of
sufficient thickness to sustain atmospheric pressure. It is preferred to use masonry
in constructing a vacuum chamber, first on account of less cost for any given sized
chamber, and second because many liquids are injuriously affected by contact with
metallic surfaces, such as are now almost exclusively employed in constructing vacuum
evaporating apparatus.
In the case of large size vacuum chambers, the difference in cost. between metal
and masonry as materials of construction, is very great, and I am enabled to construct

page_text: with masonry larger vacuum chambers than are practicable when they are built of
motal.
The tanks D, D1, D2, D3 are supposed to be constructed of masonry and lined with
Portland cement, but may of course be built of wood or metal, and they may be
covered or not, as is most convenient.
D2,
Tank D³ is designed for an overflow tank, so that in the event of tanks D, D',
not being sufficiently large to hold the liquid in case the vacuum should suddenly fail
in chambers A, A', it may overflow into the said tank. Usually, however, the three
tanks, D, D', D2 will be made of sufficient size, so as not to overflow in case of failure
of vacuum in chamber A, A', to the extent of letting the contents of the chambers*
flow out into the said tanks.
When the apparatus is arranged for triple effect, tank D³ will be required for a.
condensing tank to be used the same as tank D2 in the double effect apparatus shown.
The two greatest advantages in placing the heating surfaces as in coils B, B' outside the
vacuum chambers A A', are accessibility for cleaning, so that the said surfaces may
be cleaned even while the process of evaporation is proceeding, and provision for
removal of solid deposits as fast as they accumulate at the bottom of the vacuum
chamber. To make such removal as easy as possible, the bottom of the chamber is
given the form of a hollow inverted cone, so that the current of liquid constantly
flowing out of the chamber may carry with it, within reach of the conveyor, all solid
matter deposited by the process of evaporation within the chamber. But when it is
not necessary to provide for such rapid removal by means of a conveyor, or when the.
liquid under treatment simply thickens by concentration, but does not precipitate
solid matter the bottom of the chamber may be made flat, and such number of
arched openings provided as will render the interior of the chamber sufficiently.
accessible, the top of the arched openings being of course below the liquid level in
the tanks.
For circulating the liquid between the vacuum chambers A A³ and coils B B¹, any
suitable form of pump may be employed.
In Figures 4, 5, 6 the belt or chain of the conveyor F, is carried around pulleys f
and driven by a pulley f¹. G, G², G³ are shafts or shoots made preferably of wood
and provided with numerous cross rods of wood or metal g, for dividing up the mass
of salt, and checking its fall.
F and F are conveyors constructed and operated in manner similar to F, but
differing from the latter in being tightly enclosed in wooden cases H, H¹.
I is a hopper in which the dried salt is received previous to being delivered
by the screw conveyor J into the blast pipe k, which is connected with the fan
blower K.
Another blower L is employed for forcing air through the steam pipe coil m, in
box M, and through pipe into hopper I. From the tightly enclosed hopper the
heated air proceeds upward through shaft G2 down through H₁ of elevator F' up
through shaft G', down through case H of elevator F', and finally upward through
shaft & into the atmosphere.
Arrows feathered on both sides indicate the circulation of brine, the large arrows
feathered on one side only the movement of salt, and the arrows without any feathering
give the direction in which the elevalor belts or chains move.
The basin having a comparatively large area, the current of brine from the
passage al becomes correspondingly slow, which allows the salt to settle out of the
brine and be taken up by conveyor F, which elevates and delivers it into the top of
shaft G. The elevator is driven at as slow a speed as is consistent with taking up
the salt as fast as made. The salt drains into tank D during the process of elevation,
and when discharged into shaft G is still in a very wet condition. As the salt falls
into the shaft it strikes upon the cross rods g which are set as near together as possible
without being liable to bridge over from one rod to another with salt, so as to block
up the shaft.
The cross rods may be made of non-corrosive metal or of hard wood such as
bickory, maple &c. The rods are preferably set in parallel, but not vertical rows,

page_text: each horizontal row breaking joints" with the row above and the row below it, so
that the salt shall fall from one rod to another, to the end that the mass may become
thoroughly divided, and all the crystals separately exposed to the action of the
current of hot air ascending through the shaft G. On reaching the bottom of the
shaft G the salt is taken up by conveyor F, and elevated and delivered into the top..
of shaft G¹ which is constructed similarly to shaft G only that the cross rods are set
nearer together.
In falling through shaft G₁ the salt loses a good deal of moisture by contact with
the ascending current of hot air. The air current is given as great a capacity for
moisture as possible by first forcing it by means of blower I through the coil of steam
pipes in contained in box M.
In falling through shaft G, the salt becomes so far dried that when lifted from the
bottom of said shaft by conveyor F2 and delivered into the top of shaft G2, it has much
less tendency than previously to cling together in a mass. The cross rods g can
therefore be set closer together in shaft F than in shaft F1 without danger of
clogging with salt. Also the lower portion of each of the shafts F, F1, F2 may have.
the cross rods y set closer both vertically and horizontally than at the tops, but it is..
more especially desirable to have them so set in the case of shaft G2, as the crystals of
salt move easily among themselves as they become nearly dry.
The elevation Figure 6 shows the position of the cross rods in shaft G2.
.
It is considered that the salt will be sufficiently freed of moisture when it has fallen
through shaft G2 into hopper I. More or less drying shafts may be employed,
depending upon the degree of dryness required, the height and other dimensions of
the shafts, and the arrangement of cross rods. I therefore do not confine myself to
the use of any specific number of drying shafts.
The sides of hopper I are made sufficiently sloping so that all salt falling into it
from shaft G2 shall slide down to the centre and into screw conveyer J which is.
driven by pulley j. This conveyer forces the salt into pipe k, in which is a current"
of air maintained by blower K, which current is sufficiently strong to carry the dry
salt to any desired point of delivery. When desirable to carry the drying process
further than is done in drying shafts F, F1, F' the blast from the blower K can be
heated, but the drying can be most economically completed in the shafts.
In order that the air blast conveyor may operate successfully it is necessary that
a seal of salt be constantly maintained in the pipe of screw conveyor J, as otherwise
the pressure of air in pipe k would force air out through the screw conveyor pipe.
The requisite seal is obtained by continuing the screw conveyor pipe a sufficient
distance beyond the delivery end of the worm or screw, to make sure that this portion.
of the pipe shall be always filled with salt; and it will be easier kept filled and the pipe
may be made relatively shorter if it is given an upward turn in joining pipe k. It
is obvious that a suction or exhaust current of air may be employed as the equiva-
lent of the forced blast, and also of the screw conveyor for drawing the salt out of
the hopper I and delivering it at any desired point.
In Figures 7 to 11 B is a boiler heated by the products of combustion proceeding
from furnace F which products pass through tubes 63 in the boiler and thence upward
to and along the bottom of, the evaporating pan E to discharge flue e. The shell of
the boiler is broken away at the upper portion to show the tubes referred to, and also
the level of liquid in the boiler. Steam for heating coil a in tank A is conveyed
through pipes 64, 6; and for air and liquid pumps and any other requirements.
through, branch pipe 6. Suitable valves 67, 68 in the respective pipes control the
supply of steam.
When the liquid to be evaporated or distilled requires previous heating to remove.
air which would otherwise collect too rapidly in vacuum chambers C, C, C and
condenser coils a, a', a² of tanks A, A1, A2 and necessitate the constant use of an air
pump or pumps of large size to secure its removal, or when it is found desirable to
heat the liquid for any other purpose, and the liquid is of such a nature that its
vapor can be used for heating the coil a, and for power, no additional boiler is
required. The liquid is delivered by a pump or sufficient head through pipe into

page_text: the recuperative heater H, and passes out of the upper end of the heater through
pipe to boiler B. A check valve ³ prevents constant reaction of the boiler pressure
on the pump or head of liquid. As the liquid becomes heated in boiler B.it rises and
finally passes out through pipe which traverses heater H and extends to the
common reservoir R. The valve controls the rapidity of delivery from boiler B,
and is opened or closed correspondingly with valve h³. As the heated liquid arising
from the boiler circulates downward in pipe r, through heater H, it gradually parts
with the excess of calorie which it contains as compared with the feed liquid which
otherwise fills the heater, until it passes out at the lower end of the heater at nearly
the temperature of the feed liquid entering through pipe h. This feature is more
particularly described in United States Patents Nos. 329,072 and 329073 dated
October 27th 1885.
When the liquid leaves a deposit of solid matter in boiler B its removal while the
boiler is under pressure is provided for by a lock chamber formed. by placing
valves b, b in an extension of the lower end of the boiler. The contents of the
chamber 62 is discharged into a hopper truck J by closing the upper valve 6 and
opening the lower valve b¹.
If the liquid is of such a nature that it cannot be used for heating and power
as described, a separate boiler is provided for the latter requirements.
The liquid to be evaporated or distilled is conducted from reservoir R by pipe 2
and branch pipes r³,, to the bottoms of the heater jackets K, K1, K2 in well W
and from the upper ends of said jackets by pipes 7-8, to tanks A, A1, A³, the
supply to each tank being regulated by valves 10, 10,
,
2.8
The vacuum portion of the apparatus in each tank consists of the cylinders C, C¹. C2;
the lower ends of which remain always submerged in the liquid to be evaporated.
The height of the cylinders must be from 30 to 40 feet for a liquid having the
specific gravity of water if it is intended to maintain a high vacuum, but may be
correspondingly less in height as the degree of vacuum is lowered. A practical
vacuum is created in each of the cylinders C, CC in commencing operations by
an air pump with which each of the cylinders and condensing coils a, a, a³ are
connected by pipe B, Figure 7, and branch pipes P1 P2 also shown in Figure 11.
After the apparatus is in full operation the vacuum is maintained by a slow or
an intermittent use of the air pump for removal of air which accumulates in the
cylinders and condensers derived from the liquid which is being evaporated. A
separate air pump may be provided for each cylinder, but in case of most liquids,
especially if prepared by previous heating, air collects so slowly that a single pump
may answer for more than one cylinder; the operation will, however, be more
satisfactory if not more than two cylinders are connected with one pump.
"When the apparatus is ready for operation the liquid to be treated is introduced
to each of the tanks A, A', A through pipe connected with reservoir R until
the bases of the cylinders c, c¹, care submerged when the air pumps connected
with the cylinders and with the condensing coils a, a, a² may be started and
operated until the desired amount of vacuum is produced in the cylinders and coils.
The liquid contained in the tanks rises in cylinders C, C, C in proportion to the
degree of vacuum which has been produced therein, and more feed liquid is supplied
to the tanks, or sufficient to make up for the quantity which has been forced
upward into the chambers by pressure of the exterior atmosphere and to insure
that the bases of the cylinders shall always remain immersed in the liquid. Each
tank is preferably made large enough to avoid overflow in case the amount of vacuum
should suddenly become largely reduced in the cylinders; and the level of liquid in
the tanks is kept at such a point as to allow of the cylinders being emptied without
overflowing the tanks. As the liquid in tank A becomes heated vapor passes off
rapidly from its surface in cylinder C in proportion to the degree of vacuum," the
temperature of the liquid and the rate at which the vapor is condensed in coil a
into which.it flows through pipe c. In condensing the liquid gives off its latent heat'
to the liquid in tank A', and as this liquid becomes heated the resulting vapor escapes
from its surface in cylinder and enters, through pipe c¹, the coil a² în -tank-A³

page_text: where in condensing it heats the liquid in the tank, and the same cycle of evaporating,
condensing and heating of liquid goes on through the whole number of tanks which
compose the series. At the end of the series the vapor from the last cylinder is
condensed in a tank provided with a coil but containing no vacuum cylinder.
Each of the tanks has a cover G, Figures 7 and 11, composed of two thicknesses
of plank, between which is a layer of felt. The lower surface of the cover is protected
by sheet metal. Any other suitable materials which are non-conductors of heat
may be employed for constructing the cover, the use of the cover being principally to
prevent escape of heat by radiation and evaporation from the liquid in the tank. The
cover does not fit so closely as to entirely exclude air from the interior of the tank,
but the air passages are made small so as to prevent much escape of vapor.
as as
The liquid of condensation flows away from the coils a, a', a² by pipes a³, a¹,
fast as it forms and collects in well W from which it is pumped or otherwise
discharged in any convenient manner. When desirable that the liquid of condensa-
tion formed in each of the coils shall not be mingled, each of the pipes a³, a', as is
made to discharge into a separate receptacle. As the first coil a is under pressure of
steam from boiler B the discharge of water of condensation has to be effected in a
different manner from that suitable for vacuum coils a¹ a². A head plate k, Figures 7
and 8 is secured to the heater jacket K forming a support for the three rods k¹, and
at the opposite or lower ends of the rods is a foot plate k², carrying an elastic seat ³
against which the tip a on discharge pipe a³ impinges as the heating of jacket K and
pipe a³ causes them to lengthen by expansion. A guide plate upon pipe a³ keeps
the ends in line with this pipe and jacket K. Screw nuts on the lower ends of the
rods provide for bringing the seat more or less closely to the tip as, and the adjust-
ment is so made that the discharge of the liquid of condensation shall be stopped by
contact of the two parts when the temperature of the liquid becomes so much higher
than that of the feed liquid as it enters the jacket as to occasion an appreciable and
objectionable amount of loss of caloric. After stopping the discharge from pipe a³ it
and the jacket soon become so much cooler that contraction in their length occurs,
and the seat and tip a separate until the pipe and jacket again become heated by
discharge of the water of condensation. The discharge of said water from the vacuum
coils a', a² is effected by the Torricellian tubes a, a which connect with the coils at
one end, and dip into the liquid in well W at the other end. The vertical length of
these tubes is made at least equal to the height to which the liquid in the well would
rise in the tubes with the degree of vacuum employed. In flowing downward through
pipes a³, a, a enclosed by jackets K, K', K2 the liquid of condensation gradually
parts with its excess of heat as compared with the temperature of the feed liquid which
fills the jackets, and the latter as it rises in the jacketted space, acquires the original
temperature of the said liquid of condensation, while the latter flows away at nearly
the original temperature of the feed liquid.
In treating the large class of liquids in which precipitates are formed as the degree
of concentration increases in continued evaporation the removal of solid matters as
fast as they are deposited is effected by means of screw conveyors L, m Figures 10
and 11. Each conveyor consists of a shaft on which is secured a helix formed of
plate metal or woven wire enclosed in a case or shell 12. The shaft is driven by
bevel gear . The lower end of the conveyor is fixed at that point in the tank where
the greatest amount of deposit occurs, namely under the centre of the vacuum
cylinder. The screw as it revolves takes up at its lower end the solid matter and,
carries it to the upper end of the shell where it falls into a suitable receptacle.
In the drawings Figures 10 and 11 show a second conveyor m employed for
removing solid substances discharged from a series of tanks. This conveyor has a
double bottom m', and between the two bottoms steam or any other suitable hot liquid
is circulated when it is desired to remove remaining moisture from the material which
is being handled. This heat of steam or hot liquid may be depended on for driving
off moisture, or the process may be assisted by attaching a fan blower to one end of
the conveyor and forcing or drawing air through the case or shell in opposite
direction to the movement of solid material. The helix of this second conveyor is

page_text: formed like that of the first conveyor, or it may consist of connected or unconnected
arms fixed spirally around the shaft depending upon the nature of the material being
handled. I do not confine myself to the screw form of conveyor, either in the caso
of conveyor m or of conveyor L, as scrapers or buckets attached to chains carried
around suitable driving pulleys can be made to do almost equally well, and, in some
cases, even better than screws.
The tanks A, A1, A2 and vacuum cylinders C, C, C and all connecting pipes are
well insulated by covering with non-heat-conducting materials. As the percentage of
heat lost by radiation is thus made small, and as that heat which is contained in the
liquid of condensation is mostly returned to the tanks by the feed liquid, it becomes
possible to convey the caloric imparted to the liquid in the first tank to a number of
tanks constituting a connected series. As the number of tanks is increased the
amount of condensing surface in each coil requires to be correspondingly increased in
order to obtain the same amount of liquid. of condensation in a given space of time.
This is a feature of the invention which is applicable to all multiple effect vacuum:
apparatus. In general it is found that an increase of condensing (or heating) surface
of twenty five per cent. for each effect gives economical and satisfactory results.
Although the apparatus described is designed primarily to be used in series, it is
equally well adapted for use as a single effect apparatus in substitution for the
ordinary vacuum pan. Among the advantages over the common vacuum pan are less
first cost; accessibility for removal of deposits without stopping the process of
evaporation; better opportunity for observing the condition of the liquid under
treatment; convenience in cleaning the heating surfaces, and the less diameter and
stronger form which can be given to the cylinder for a given capacity. The
apparatus described is suitable for evaporating all kinds of liquids where ordinary
vacuum pans would be employed, but in removing moisture from semi-solid substances
the process cannot be carried so far in the tanks A, A1, A2 as in vacuum pans for the
reason that the material treated must contain sufficient liquid to form a seal at
the bases of the cylinders C, C, C to prevent access of air to the interiors of the
cylinders; but by withdrawing from the tanks, by means of conveyors L, L', solid
matter as fast as deposited, and finishing the drying process in a secondary
conveyor m, the apparatus is made not only the equivalent of ordinary vacuum pans
but greatly superior to them in many uses.
The vacuum cylinders C, C, C are made of suitable diameter for the amount of
liquid to be evaporated in each; and the height is determined by the degree of
vacuum to be maintained.
By the arrangement of valves and pipes shown in Figures 7 and 10 any one or
more cylinders of a series can be cut off or detached from the remaining cylinders of
a series without stopping the process of evaporation in those cylinders which remain
connected.
I do not confine myself to the form of condenser coils made up of pipes as shown;
nor to any particular shape of tank, as these may be put in a variety of shapes having.
about the same effect. The most important point in connection with the condensing
surface is that it shall be sufficient in extent to condense the required weight of
vapor at the difference in temperature between the liquid in the tank in which it is
placed and that. in the tank which precedes it; and that which is most essential in the
tank is that it shall not have an air tight cover, and that it shall be sufficiently large
to contain the vacuum cylinder, the combined heating and condensing coil and the
necessary amount of liquid.
-
1
The apparatus described is especially suited for carrying on evaporation on a large
scale, as in evaporating brine in the manufacture of common, salt, and cane and beet
juice in making sugar; also in the distillation of petroleum, alcohol &c. As the
general description given is applicable for most liquids which require to be evaporated,..
it is not deemed necessary.to single out any particular one and trace the operation in
connection therewith.
The increased amount of heating or condensing surface, required in each succeeding,
tank of a series is not shown in plan in the drawings, but tank A³ is shown broken i

page_text: two in Figure 10, and the dotted or broken lines g, g' Figure 11, indicate respectively
the lengths of the tanks A and A' in order to give room for the amount of heating
surface required in each.
In Figures 12, 13, 14 and 15 of the drawings B represents symbolically a closed
tank or boiler in which the liquid to be evaporated is heated by any ordinary or well
known means. The form of this liquid heating apparatus is of secondary importance,
provided it is adapted to impart a high degree of heat to the liquid passing through
it, and is closed to the atmosphere.
The vacuum chamber V is shown as situated in an open sealing tank T which also
acts as a supply tank for the introduction of fresh brine or other liquid into the
circulation. But this sealing and supply tank T is not absolutely essential to the
carrying out of the process as far as the circulation between the closed heater B and
the vacuum chamber V is concerned, since both the injection pipe I and the return
pipe R may be connected directly with the vacuum chamber as shown in Figures 14
and 15, instead of having the return pipe R.connected with the sealing and supply
tank T as in Figure 12, the effect in either case being substantially the same as far as
the augmentation of evaporation by the circulation between the closed boiler B and the
vacuum chamber V is concerned.
This circulation of the liquid may of course be effected alone by the natural action
of gravity, the hot liquid passing upward through the injection pipe I into the vacuum
chamber V, and that which remains unevaporated finally returning to the boiler B by
means of the return pipe R.
But it is preferred in most cases to employ a forced circulation of the liquid under
treatment through and between the closed heater and the vacuum chamber.
The
This may be accomplished by the use of a force pump P or equivalent means.
injection and return pipes may each. be provided with a valve i and r for regulating
the flow of the liquid.
It is obvious that the liquid under treatment may be injected from the boiler B
into the vacuum chamber V at any angle; but it is preferred to inject it at an angle
which is substantially tangential to the inner walls of the vacuum chamber V, so as to
cause the liquid to rotate within the said chamber, thereby creating a vortex move-
ment which draws the more concentrated liquid and crystals by centripetal action to
the central portion of 'the 'chamber where the liquid is comparatively quiet, the
crystals descending gradually to the bottom of the vacuum chamber.
The upper portion of the vacuum chamber is connected with an exhaust apparatus
by the pipe E in the usual manner; and its lower extremity is provided with a
discharge passage through which the concentrated liquid and the crystals are
delivered preferably into a separating basin S.
In lieu of discharging the products of evaporation into a separating basin S-the
latter may be dispensed with and such products may be discharged directly into the
supply tank T,, or the discharge passage v may be provided with a valve vl, and
such products after the collection of a sufficient quantity in the bottom of the vacuum
chamber V may be discharged at suitable periods into any convenient receptacle as
heretofore.
When the separating basin is used, the discharge passage is made to enter it at an
angle which is substantially tangential to its sides as indicated in the drawings, thus
insuring a gyratory movement of the discharged products of evaporation within the
basin S, by which means the crystals are collected for removal centrally.
By the use of the closed heating apparatus B a higher temperature may be imparted
to the liquid to be evaporated as compared with my system of heating the liquid in an
open tank as hereinbefore set forth, and the rapidity and effectiveness of the process
will thereby be.increased:
By means of the tangential delivery. into the vacuum chamber and thereby creating
a whirling notion of the liquid under treatment within said chamber, I not only draw
the crystals as formed downward, but also favor the production of crystals of uniform
size by giving the liquid a steady, even motion in one direction, thus preventing the
agitation occasioned by opposing currents.

page_text: It will be readily understood that in so far as the gyratory movements of the liquid
in the vacuum chamber and separating chamber are concerned, it is immaterial
whether the heat for effecting the evaporation is imparted to the liquid in an open or
closed heater.
Having now particularly described and ascertained the nature of the said inven-
tion as communicated to me and in what manner the same is to be performed I
declare that what I claim is :-
1. In apparatus substantially such as described, the combination of a Vacuum
chamber, an exterior tank for heating the liquid under atmospheric pressure, and
apparatus for enforcing a circulation of the heated liquid through and between the
said vacuum chamber and heating tank, substantially in the manner and for the
purpose described.
2. In evaporating apparatus substantially such as described, the combination of a
vacuum chamber, an exterior tank for heating the liquid under atmospheric pressure;
apparatus for enforcing a circulation of heated liquid through and between the said
vacuum chamber and heating tank; and an automatic conveyor for removing the
solid products of evaporation, substantially in the manner and for the purpose
described.
3. In evaporating apparatus substantially such as described, the combination of a
vacuum chamber formed with converging side walls which concentrate the solid products
of evaporation at the bottom of the chamber; an exterior tank for heating liquid under
atmospheric pressure, apparatus for enforcing a circulation of heated liquid through
and between the said vacuum chamber and exterior heating tank, and an automatic
conveyor for removing the solid products of evaporation from the lower portion of the
vacuum chamber, substantially in the manner and for the purpose described.
4. A vacuum chamber constructed wholly of masonry for the purpose and sub-
stantially in the manner described.
5. A vacuum chamber constructed of masonry and coated on the outside surface
with thin sheet metal or other thin air-proof material, for the object and substantially
in the manner set forth.
6. In evaporating apparatus substantially such as described, the combination of a
vacuum pan, an exterior tank for beating liquid under atmospheric pressure, a heating
coil situated in the said liquid heating tank and communicating with the vacuum space
in the said vacuum chamber, and apparatus for exhausting the vapor from the said
vacuum chamber through the said heating coil, substantially in the manner and for
the purpose described.
7. In evaporating apparatus substantially such as described, two or more vacuum
cbambers, two or more exterior tanks for beating liquid under atmospheric pressure;
heating coils arranged in the said exterior heating tanks and each communicating with
the vacuum space in the next preceding vacuum chamber; and apparatus for with-
drawing the vapor from the vacuum chambers through the said heating coils in such
manner that the vapor from one vacuum chamber is utilized to heat the liquid for the
next succeeding vacuum chamber, substantially in the manner described.
8. In evaporating apparatus substantially such as described, the combination of
two or more vacuum chambers, two or more exterior tanks for heating liquid under
atmospheric pressure, heating coils situated in said exterior tanks and communicating
with the vapor spaces of the said vacuum chambers, and a duplex exhaust pump
connected with said heating coils and provided with valves by which the action of
the pump upon the respective coils may be varied, substantially in the manner and
for the purpose specified.
9. The process of manufacturing salt continuously, consisting in separating the
salt from the brine by evaporation, removing the salt from the evaporator auto-
matically, and drying it in the process of removal by keeping it in an agitated
state and passing a current of air through it-the air and the salt moving in opposite
directions, substantially in the manner herein set forth.
10. The process herein set forth of augmenting the evaporation of brine or other

page_text: . liquid in vacuum apparatus, consisting in heating the liquid under atmospheric
pressure and forcibly circulating it through and between the open heating tank and
the vacuum chamber, substantially in the manner described.
11. In the manufacture of salt and evaporation of liquids leaving solid residuum,
the process herein described of removing the solid products of evaporation from the
vacuum chamber by a forced circulation of the brine or other liquid being evaporated
through and between said vacuum chamber and a tank in which the brine or other.
liquid is heated under atmospheric pressure, substantially in the manner and for the
purpose set forth.
12. In vacuum apparatus the combination substantially as and for the purpose set
forth, of a tank open to the atmosphere for containing the liquid to be ovaporated, a
vacuum chamber opening at its lower end into the said tank and sealed by the liquid
therein, and a heater arranged to impart heat to the liquid in the tank to effect its.
evaporation within the said vacuum chamber.
13. The combination, substantially as set forth, of a series of separate evaporating
apparatus each consisting of a tank open to the atmosphere for containing the
liquid to be evaporated, a vacuum chamber opening at its lower end into the said
tank and sealed by the liquid therein, and a heater arranged to impart heat to the
liquid in the tank to effect its evaporation within the vacuum chamber, the upper
portion of the vacuum chamber in one tank being connected with the combined con-
densing and heating coil in the next succeeding tank or member of a series, for the
purpose described.
14. In a vacuum apparatus, the combination substantially as and for the purpose
set forth, of a tank open to the atmosphere for containing the liquid to be evaporated,
a vacuum chamber opening at its lower end into the said tank and sealed by the liquid
therein, a heater arranged to impart heat to the liquid in the tank to effect its
evaporation within the said vacuum chamber, a conveyor for removing solid matters
from the tank or tanks, and a second conveyor formed with a steam chamber for
heating the said conveyor and its contents.
15. In vacuum apparatus arranged in series for multiple effect substantially as
described, the tanks A, A' A², sufficiently open at the top to receive atmospheric
pressure, a vacuum chamber arranged in each tank and supplied therefrom, and a
condenser coil in each tank, except the first, connected with the upper portion of
the vacuum cylinder in the next preceding tank of the series, each condenser coil
having a greater surface than the next preceding one, substantially as described. ...
16. The process of evaporating liquids consisting in imparting the heat to effect
the evaporation in the vacuum chamber to the liquid in a separate heater and then
transferring such heated liquid into the vacuum chamber, substantially as and for
the purpose set forth.
17. The process of evaporating liquids consisting in imparting the heat to effect
the evaporation in the vacuum chamber to the liquid in a separate closed heater and
then transferring such heated liquid into the vacuum chamber, substantially as and
for the purpose set forth.
18. The process of evaporating liquids substantially as and for the purpose set
forth, consisting of imparting the heat, to effect the evaporation in the vacuum
chamber to the liquid in a separate closed heater, and causing the liquid to circulate in'
and between the said heater and the vacuum chamber.
19. The process of evaporating liquids substantially as and for the purpose.set
forth, consisting in imparting the heat to effect the evaporation in the vacuum
chamber to the said. liquid in a separate closed heater, and causing the liquid to
circulate in and between the said heater and vacuum chamber by means of a forced.
circulation.
purpose
20. The process of evaporating liquids substantially as and for the
herein set forth, consisting in imparting the heat to effect the evaporation in the
vacuum chamber to the said liquid in a separate heater, and injecting the said heated.
liquid into the vacuum chamber in a line which is substantially tangential thereto. in
such manner as to impart a gyratory motion to the liquid.

page_text: 21. The process of evaporating liquids substantially as and for the purpose herein
set forth consisting in imparting the heat to effect the evaporation in the vacuum
chamber to the said liquid in a separate heater, injecting the said heated liquid into
the vacuum chamber in a line which is substantially tangential thereto in such manner
as to impart a gyratory motion to the liquid to effect the collection of crystals, and
returning the unevaporated liquid to the exterior heater to be reheated and again
introduced into the vacuum chamber.
22. The process of evaporating liquids substantially as and for the purpose set forth
consisting in imparting the heat to effect the evaporation within the vacuum chamber
to the said liquid by means of an exterior heater, introducing the heated liquid into
the vacuum chamber, and discharging the products of evaporation therefrom into a
separating basin in such manner as to create therein a vortex movement by which the
crystals are separated from the liquid constituent.
23. The process of evaporating liquids substantially as and for the purpose herein
set forth, consisting in imparting the heat to effect the evaporation within the vacuum
chamber to the said liquid by means of an exterior heater, introducing the said liquid
into the vacuum chamber, discharging the products of evaporation therefrom into a
separating basin in such manner as to create therein a vortex movement by which the
crystals are separated from the liquid constituent, and returning the said liquid con-
stituent to the said exterior heating apparatus to be re-heated and again introduced
into the vacuum chamber.
24. The process of evaporating liquids substantially as and for the purpose herein
set forth, consisting in imparting the heat to effect the evaporation within the vacuum
chamber to the liquid by means of an exterior heater, injecting the said heated liquid
into the vacuum chamber at an angle substantially tangential thereto, to facilitate the
concentration of the products of evaporation, and discharging the said products of
evaporation from the vacuum chamber into a separating basin at an angle substan-
tially tangential thereto, to separate the crystals from the liquid constituent.
25. The process of evaporating liquids substantially as and for the purpose herein
set forth, consisting in imparting the heat to effect the evaporation within the vacuum
chamber to the said liquid by means of an exterior heater, injecting the said heated
liquid into the vacuum chamber at an angle substantially tangential thereto, to
facilitate the concentration of the products of evaporation, discharging the products
of evaporation from the vacuum chamber into a separating basin at an angle sub-
stantially tangential thereto to separate the crystals from the liquid constituent, and
returning said liquid constituent to the said exterior heater to be re-heated and again
introduced into the vacuum chamber.
26. The process of evaporating liquids substantially. as and for the purpose set
forth, consisting in imparting the heat to effect the evaporation within the vacuum
chamber to the liquid by means of an exterior heater, injecting the said heated liquid
into the vacuum chamber at an angle substantially tangential thereto to facilitate the
concentration of the products of evaporation, discharging the said products of
evaporation from the vacuum chamber into a separating basin at an angle substan-
tially tangential thereto to separate the crystals from the liquid constituent, and
returning said liquid constituent to the said exterior heater to be reheated and again
introduced into the vacuum chamber, the whole process and operation being effected
and maintained continuously by a forced circulation of the liquid under treatment
substantially in the manner described.
+000
J. C. MEWBURN.