Improvements in Methods of and Apparatus for Evaporating Liquids.
Year: 1892

page_text: Date of Application, 13th Sept., 1892-Accepted, 12th Nov., 1892
COMPLETE SPECIFICATION.
Improvements in Methods of and Apparatus for Evaporating Liquids.
I, CHARLES WILLIAM COOPER, of 115 East Twenty First Street, in the City
of New York, County of New York, State of New York, United States of
America, Manufacturer, 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 :-
Generally stated the object of my invention is the practice of a method, and the con-
struction of an evaporating apparatus by the practice or use of which a very rapid
rate of evaporation in proportion to the heating surfaces can be effected, and in which
a high degree of concentration of such liquids as are ordinarily difficult to evaporate
to a thick consistency may be obtained.
In evaporating apparatus as heretofore constructed to evaporate liquids while
in transit through tubes, it has been found that the greater the required consistency
of the concentrated liquid the smaller must be the rate of supply of said liquid,
with the result that the amount of liquid which it has been possible in a given time
to supply to the tubes has been found too small to sufficiently scour their surfaces
and thereby bring about effective evaporation.
I have discovered that this difficulty can be overcome by the provision of an
apparatus and the practice of a method such as are hereinafter set forth, in which,
while the liquid may be fed into and discharged from the evaporator continuously, the
supply into the evaporator may yet be so limited and controlled as to ensure a high
rate of concentration, while at the same time the supply into the evaporating tubes
is only necessarily limited by the rate at which the liquid supplied to the evaporator
as a whole can be caused to circulate through said tubes.
By my invention provision is made for the continuous circulation of the same
liquid repeatedly from a tube supply chamber through evaporating tubes into a
separating chamber and thence again to the tube supply chamber, so that with
but a limited supply into the evaporator the pipes may have as much liquid
circulating through them as they would have in the case of a larger supply. In
my apparatus, moreover, as hereinafter explained, provision is made by which the
evaporating apparatus is composed of a series of associated and connected
evaporators, the distinction being that when a high degree of concentration is
desired the thinner liquor of one evaporating chamber is prevented from mixing
with the thicker liquid of a succeeding chamber, with the result that within the
apparatus as an entirety the average consistency is less than it is in the
final chamber, whereas if but a single chamber be employed the liquor circulating
within it would necessarily be of the consistency of the liquor discharged from
said chamber.
Of course a less average consistency of the liquor in a divisional or compartment
evaporating apparatus is conducive to a better rate of evaporation than
where the average consistency is greater as in the case of a single compartment
evaporator.
Whatever, however, be the arrangement of apparatus to which I resort, my
invention comprehends an evaporating apparatus into which the supply is continuous,
out of which the discharge is continuous, and within which the circulation of the
liquor is continuous, all as hereinafter explained.
In the accompanying drawings I have illustrated and herein I describe two forms
of evaporating apparatus alike embodying my invention so far as it is concerned
with apparatus, and alike adapted to effectuate my method of evaporation.
Of these views Figure 1 is an elevation (the left hand half being in section) of
an apparatus embodying my in provements in a simple and inexpensive form..

page_text: Figure 2 is a similar view of a modified form of the same apparatus, and
Figure 3 is a transverse section through the evaporating chamber of the apparatus
of Figure 2.
Similar letters of reference indicate corresponding parts.
Referring first to Figure 1,-A A' A' represent three vertical and conveniently
cylindrical evaporating chambers, all of the same construction and all applied in
connection with a common vapor chamber. It will, therefore, for the purpose of
this explanation, suffice, to describe the construction of the chamber A, and of such
parts of the apparatus as are associated and operative in connection with it :-it
being understood that counterparts of all such parts are employed in connection
with the other chambers.
Within the chamber A are a group of vertically disposed parallel open-ended
evaporating tubes B, respectively supported by being at their extremities tightly
connected with and caused to pass through a lower tube head E and an upper tube
lead F.
These tubes place a tube supply chamber C formed at the base of the evaporating
chamber A in communication with a separating chamber D shown here but not
necessarily of conical form and located above the upper tube head.
The tube heads, within which, as stated, the ends of the tubes are closely fitted
so as to be fluid tight, serve to separate the steam space of the evaporating chamber
from both the tube supply chamber and the separating chamber, and in connection
with its cylindrical walls constitute it a closed chamber.
The upper tube head is conveniently peripherally extended to form an annular
flange F, the outer edges of which extend so nearly to the walls d of the
separating chamber as to leave only an annular passage f between said flange
and walls.
G is an annular pocket surrounding the upper portion of the evaporating
chamber below the flange F', conveniently formed by the cylindric downward
extension d of the walls d and by the base plate g.
H is a vertical channel or conduit opening at its upper extremity through the
base plate g of the pocket G, and at its lower extremity opening into the tube
supply chamber C, and thereby serving to place the pocket in communication with
the tube supply chamber.
Supported above the upper tube head is a horizontal disk shield or deflector T,
between the outer edges of which and the walls d of the separating chamber, is an
annular opening t.
This deflector is conveniently supported from the flange Fl by a series of
brackets or angle irons t*, and it serves the purpose of a radiating device to
occasion radial deflection of the vapor and liquid. Other devices operative to a
kindred result may obviously therefore be substituted in its stead.
Above and in communication with each separating chamber, and common thereto,
is a vapor chamber I, having a vapor outlet J for the final discharge of the vapor
resulting from evaporation.
K is a steam-supply pipe, having three branches or pipes k k₁ k² leading
respectively into the respective evaporating chambers A A' A². This pipe is
conveniently arranged at the height shown. L is a discharging pipe, having three
branch pipes respectively leading out from the respective evaporating
chambers near their lower portions.
The steam-supply pipe is provided with a suitable cock * for controlling the
supply, and the discharge pipe is similarly provided with a cock /* for controlling
the discharge.
M is a feed pipe for supplying the liquid to be evaporated into the pocket of the
first evaporating chamber, and this pipe is also provided with a cock in to regulate
the feed.
N is an overflow passage from the pocket G into the pocket G' of the evaporating
chamber A¹, and O is a similar passage from the pocket G₁ into the pocket G³ of

page_text: P is a final discharge pipe from the pocket G for the concentrated liquid. In
practice these pipes are to be placed as close to the base plate g as possible.
It being, as already stated, borne in mind that the evaporating chambers A¹ A²
and their associated parts are similar to the chamber A and the parts as described
as in association therewith, the operation of the apparatus as an entirety will be
readily understood:-Steam being supplied to all of the evaporating chambers
through the steam supply pipe K and its branches, the liquid to be evaporated
is continuously supplied into the pocket G of the first chamber, from which it
descends through the conduit H into the first tube supply chamber C. From out
this last named chamber the liquid rises within the evaporating tubes B, and as it
ascends is subjected to the heat of the steam which surrounds said tubes within the
evaporating chamber A, with the result that much of the liquid is rapidly converted
into vapor which, partly by reason of the difference in specific gravity of the
column within the conduit H and the columns within the tubes B, ascends through
the tubes with great velocity, and, in escaping through their upper apertures,
carries with it a portion of the unvaporized liquid which strikes against the under
side of the deflector T and is, together with the ascending vapor, deflected
horizontally against the walls d of the separating chamber with the result that the
liquid, being heavier than the vapor and possessing such correspondingly greater
momentum as to be driven against the walls d with greater force, is deflected by
the inclination of the walls downward into the pocket G, while the vapor passes
upward through the passage t into the vapor chamber I whence it escapes through
the discharge outlet J.
The liquid falling into the pocket G again descends through the conduit H into
the tube supply chamber C, and again ascends through the evaporating tubes B in
a continuous circulation, the surplus liquid supplied through the feed pipe in
excess of the evaporation, escaping however, through the overflow passage N into
the pocket G' of the second evaporating chamber A¹.
There is thus continuously supplied to the second evaporating chamber the excess
of the unevaporated liquid from the first supply chamber, and into the third
evaporating chamber the excess of liquid from the second chamber, and the
operation already described with reference to the first chamber being repeated in
each of these chambers, the concentrated liquid is finally continuously discharged
from the third evaporating chamber through the final discharge pipe P.
In each of these last two chambers the evaporation proceeds under the same
conditions as in the first, except in so far as the conditions are modified by the
increased consistency of the liquid in each succeeding chamber.
The first evaporating chamber A with its connected appliances manifestly
constitute a complete evaporator without the other chambers, and when a series of
two or three or more chambers are employed they constitute but sub-chambers of a
single evaporating apparatus, the object of the succeeding chambers being merely
to occasion the evaporation of a portion of the thinner liquid before it becomes
commingled with the thicker liquid of a succeeding chamber, to the end that the
average consistency of the liquid under evaporation may be less than the con-
sistency of the liquid as finally discharged.
A further object of employing a series of evaporating chambers arises from the
fact that the thicker the consistency of the liquid in process of evaporation the
more the process of evaporation will become impeded; and from the further fact
that, in the case of the employment of but a single chamber the thinner liquid,
becoming as soon as it enters commingled with the thicker liquid that is being
discharged, the process of evaporation will be retarded and rendered less
satisfactory.
Under these circumstances it will be apparent that, in the case of many liquids,
the greater the number of the sub-divisions of the apparatus, the less will be the
average consistency of the liquid under evaporation. Where, however, the liquid
is not to be evaporated to a consistency materially impeding the operation, it is not

page_text: essential to have more than a single chamber containing any preferred number of
evaporating tubes.
In the practice of this invention, in which, as explained, the continuous
circulation of the liquid to be evaporated in each evaporating chamber forms the
most prominent feature,-I have discovered that the circulation and evaporation
in each individual evaporating tube does not go on with entire and continuous
uniformity, but that pulsations take place at intervals of a few seconds. For
example, the liquid entering one of the evaporating tubes ascends a certain
distance before becoming vaporized, and then at a certain level becomes instantly
converted into a vapor which expels itself from the tube with great velocity
carrying with it some of the liquid.
The upward passage of this liquid, moreover, sweeps from the interior walls of
the tube the lining of the thicker liquid from the preceding pulsation, that, in the
interval, has been evaporating upon said walls, and replaces it by a lining of thinner
liquid which in turn evaporates until driven off by the next pulsation. If, therefore,
any bubbles or other non-conducting coating be formed upon the heating surfaces,
they are being constantly swept off and replaced by the thinner liquid.
It is obvious that, if desired, two or more evaporators of the character
represented in Figure 1 of the accompanying drawings, may be coupled to produce
an effect of multiple evaporation, the vapor discharge pipe J of the first of these
evaporators being connected with the steam or vapor supply pipe of a second
evaporator, with the result that a double effect evaporator is obtained. In such
multiple arrangement, the supply pipe K of the second evaporator and its branches
should be enlarged so that the vapor from the vapor chamber I of the first
evaporator may pass into the evaporating chamber of the second evaporator
without loss of pressure. The series of evaporators, with a corresponding coupling
arrangement, may of course, be extended to three or more.
Referring now to the apparatus represented in Figures 2 and 3, which represent
a single evaporating apparatus of a modified construction,--susceptible however, of
such mechanical modification as to permit of its being used in multiple arrangement,
the evaporating chamber A is disposed horizontally and the group of evaporating
tubes B are led into it at the left hand end, through a lower tube head E in
connection with a tube supply chamber C. Springing from this tube head the
tubes, rising vertically to a given distance, are bent at right angles and carried
along horizontally to an upper tube head F at the right hand end of the apparatus,
through which they pass and discharge against a deflector or diaphragm T,
erected in a suitable separating chamber D formed at the right hand extremity of
the apparatus. An inclined diaphragm d corresponding to the deflecting walls d of
the separating chamber of the apparatus of Figure 1, stops short of the inner wall
of the separating chamber so as to leave a passage f correspondent to the annular
passage in the apparatus of Figure 1.
G is a pocket formed in the separating chamber, and J a vapor outlet from the
upper portion of said separating chamber, which upper portion in effect constitutes
a vapor chamber.
K is a steam supply pipe and L a discharge pipe for the condensed water, both
arranged in connection with the evaporating chamber A.
H is a return channel or conduit leading from the pocket G, into which conduit
leads the liquid pipe M for supplying liquor to the apparatus. The conduit H
leads into a liquid pump Px of any preferred character, a centrifugal device
answering the purpose, and out of said pump the conduit leads and continues, under
the designation of H*, to its discharge into the tube supply chamber C.
A belt Q and driving pulley R are shown as a driving device for the pump.
N is an overflow passage or discharge led from the pocket G.
The operation of this apparatus is essentially identical with that of the
evaporator A of the apparatus of Figure 1, and all of its parts perform the
same functions as the corresponding parts in said evaporator, the only distinction

page_text: being that the circulation between the pocket of the separating chamber,-the
discharge from which is below the level of the tube supply chamber,―and
the tube supply chamber, is occasioned by the action of the pump which sucks the
liquid from the pocket into its own casing and thence forces it into the liquid
supply chamber.
Of course in the operation of this apparatus the surplus of the liquid which is
continuously fed into the evaporator over that which passes off as vapor is con-
tinuously discharged from the overflow passage N in the form of a concentrated
liquid resulting from the evaporation. In this form of apparatus a rapid circulation
can be produced of many times as much liquid in a given time as the quantity
which in the same time is fed into the apparatus, and in the forced circulation
taking place in it a greater scouring effect upon the interior of the tubes can be
produced than in the natural gravitative circulation taking place in the apparatus
in Figure 1.
The modification represented in Figure 2 is to be understood simply as a type of
variation of the apparatus generically as such represented by the apparatus of
Figure 1.
Formal re-arrangement or modification in which however the retention of the
return channel or conduit which makes the continuous circulation possible, is a
feature, may obviously be resorted to without departure from the invention.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is :
1. The improvement in the art of evaporating liquids, which consists in con-
tinuously supplying the liquid to an evaporating apparatus and in causing it to
continuously and repeatedly circulate therein prior to and during its continuous
discharge therefrom, substantially as set forth.
2. The improvement in the art of evaporating liquids, which consists in con-
tinuously supplying the liquid to an evaporating apparatus and in causing it to
continuously and repeatedly circulate therein, and in continuously discharging it
from said apparatus into a second evaporating apparatus and in causing it to
similarly circulate therein prior to and during its continuous discharge therefrom,
substantially as set forth.
3. The method of evaporating liquid, which consists in continuously supplying
the liquid to an evaporator, in causing it to circulate continuously and repeatedly
therein through a tube supply chamber, evaporating tubes, a separating chamber,
and a return conduit, and in evaporating the liquid while it is in circulatory transit
through the evaporating tubes by the action of heat supplied to said tubes, and in
continuously discharging the concentrated liquid from the evaporator, substantially
as set forth.
4. The method of evaporating liquids, which consists in continuously supplying
the liquid to an evaporator, and in causing it to circulate continuously and
repeatedly therein through a tube supply chamber, evaporating tubes, a separating
chamber and a return conduit, and in evaporating the liquid while in circulatory
transit through the evaporating tubes by the action of heat supplied to said tubes
and in continuously discharging the concentrated liquid from the evaporator named
into a second similar evaporator in which a similar continuous circulation is set up
and a similar continuous discharge effected, substantially as set forth.
5. The combination to form an evaporator, of a tube supply chamber, a vapor
and liquid separating chamber, evaporating tubes leading from said tube supply
chamber to said separating chamber and passing through an evaporating chamber,
a return channel or conduit from said separating chamber to said tube supply
chamber, means for supplying liquid to the tube supply chamber, means for dis-
charging the concentrated liquid from the separating chamber, a vapor exit from
the separating chamber, and means for supplying a heating medium to the
evaporating chamber, substantially as set forth.

page_text: 6. The combination to form an evaporating apparatus, of a tube supply chamber,
a vapor and liquid separating chamber, evaporating tubes leading from said tube
supply chamber to said separating chamber, an evaporating chamber or casing
enclosing the evaporating tubes and provided with tube heads through which the
tubes pass, a return channel or conduit leading from the lower portion of the
separating chamber back to the tube supply chamber, a deflector or diaphragm
within the separating chamber, a liquid supply pipe, a discharge outlet from the
separating chamber, and means for supplying a heating medium to the evaporating
chamber, substantially as set forth.
7. The combination to form an evaporating apparatus, of a series of evaporating
chambers each composed essentially of a tube supply chamber evaporating tubes a
separating chamber and a return channel or conduit, and each provided with means
for supplying a heating medium to heat the evaporating tubes, all of the
separating chambers being in communication by means of liquid passages, the
first being provided with a liquid inlet for the liquid to be evaporated and
the last being provided with a liquid outlet for the condensed liquid, and all of
them being in communication with a common vapor outlet, substantially as set
forth.
Dated this 8th day of August A.D. 1892.
CHARLES WILLIAM COOPER.