Improvements in Apparatus for Evaporating or Distilling or Effecting Interchange of Heat.
Year: 1889

page_text: Date of Application, 15th July, 1889
Complete Specification Left, 7th May, 1890-Accepted. 7th June, 1890
Improvements in Apparatus for Evaporating or Distilling or
Effecting Interchange of Heat.
We, RICHARD CHARLES GARTON and CHARLES HENRY GARTON both of Southampton
Wharf, Battersea in the County of Surrey, Brewers, and WILLIAM LAWRENCE of
22 St. Mary Axe in the City of London, Brewer's Engineer, do hereby declare the
nature of this invention to be as follows:
This Invention has reference to apparatus for evaporating or distilling or effecting
interchange of heat. The improved apparatus comprises an arrangement or set of
vessels each containing one or more tubes or cylinders and so placed with regard
to each other that the liquid to be evaporated and the heat employed in the
evaporation may be dealt with in the most satisfactory or advantageous manner and
with great economy of fuel.
The vessels are arranged so that the tubes contained in thein are vertical or nearly
so, and the liquid to be evaporated flows down the tubes in a film on the one side,
while the steain or heating inedium is acting upon the reverse side.
In some cases it is intended that the vapour generated in one vessel shall form the
heating medium for the next, and so on throughout the series.
In other cases it is intended that the steam generated from a group of vessels
or from two or more vessels shall be the heating medium for the next group or
set of vessels and so on.
In other cases it is intended that one or more vessels shall be supplied singly or
separately with steam direct from the generator.
The steam or heating medium may be supplied to the apparatus at a pressure either
above or below that of the atmosphere, or it may be the waste steam from engines,
and in such case the apparatus would act as a surface condenser.
In some cases the liquid to be evaporated is intended to be supplied from one vessel
to another in succession. In other cases the liquid to be evaporated is intended to be
supplied from one group of vessels to another group of vessels in succession. lu
other cases also the liquid is intended to be supplied separately or to each vessel, and
not in succession.
The tubes or cylinders are fluted, grooved, corrugated or channelled spirally,
laterally or longitudinally, or they are spirally twisted, and they may have spiral
metal pieces combined or attached, or the tubes are plain cylinders or truncated
cones with internal or external spiral pieces attached, whereby the liquid, whilst
being evaporated is caused to traverse a greater distance than if traversing the
walls of a plain cylinder.
When the liquid to be distilled is intended to flow down the inside of the tubes
plain tubes are used having internal spiral metal pieces surrounding an internal per-
forated tube which will form a steam space, the perforations allowing the steam to pass
from the beating surfaces of the tubes into the steam space.
When the liquid to be evaporated is intended to pass down the tubes externally,
they may be either plain or corrugated or fluted, grooved or channelled spirally,
aterally, longitudinally or be spirally twisted, or they may be truncated cone shaped
or other shaped. They may also have spiral metal pieces attached externally.
It is intended to use a condenser attached to or in combination with the last
vessel of the set to condense the vapour from the last evaporation; such condenser
may be a surface condenser or an ordinary jet condenser or a condenser such as the
evaporating apparatus already herein described.
When only one evaporation is desired then the apparatus is made to consist of a
ingle evaporating vessel and a condenser as previously named and the necessary
attachments for steam and liquid and other requisites.

page_text: When the redistillation or more than one evaporation of the liquid or the economy
of heat is desired, then the apparatus is made to consist of a number of vessels in
which one or more vessels act as the condensers for one or more vessels of the previous
vessel or set. In such case a condenser is only needed to condense the vapour arising
from the last vessel or set. In this case the apparatus also includes an arrangement
of a liquor supply main or mains and a condensed liquor main or maius, so constructed
as to pass onwards to the next vessel or vessels in succession the liquid or the vapour
arising from such liquid. It must be borne in mind that the pressure and temperature
of the liquid and vapour in the first vessel will be higher than the next and so on, and
that the liquid on escaping from each vessel will give off vapour. This vapour must
not be lost, but must be passed on to the next vessel or vessels in succession; other-
wise during a great many transmissions the whole of the original heat units will be
lost. It will also form a part of this arrangement to employ cooling apparatus for
A suitable
both the condensed liquid and for the residuary liquid not distilled.
apparatus to cool the condensed liquid,--it not being of a corroding nature, is a
vessel identical with the evaporating vessel where only one tube is encased, the
condensed liquid would flow upwards between the jacket and the tube while the
liquor to be heated would flow inside the tube. To cool the residuary liquid
auy suitable refrigerator may be used, care being taken to provide against
corrosion.
In the construction of the apparatus the vessels containing the tubes are some-
times provided with a top and bottom tube plate and sometimes with a bottom
tube plate or one tube plate only, such tube plate or plates being affixed to a
suitable chamber or chambers for the reception of the vapours and the liquids that
are being condensed and distilled. The tubes may be fixed into the tube plate by an
expanding mandril or in any suitable way.
When the liquid flows internally, or inside the tubes, both a top and bottom
tube plate are needed. A distributing arrangement is also provided for supplying
the tube or tubes with a feed regulation. Removable doors and covers are also
provided for cleaning out and otherwise gaining access to the tubes. Sight holes,
man holes and steam traps are also provided.
When the liquid is arranged to flow externally either one plate or a bottom plate or
top and bottom plates are employed. If only one plate is used a removable cover may
form part of the jacket or chamber. In such case the liquid will be delivered to the
distributing feed arrangement attached to the top of the pipes by means of a stand
pipe through which the liquid will be conveyed through or from the bottom of the
vessel. If top and bottom plates be used, then the jacket or casing not being remov-
able will require to be of sufficient size and furnished with a man-hole to allow of a
man entering for cleaning or other purposes. Sight holes and steam traps should also
be provided.
When a single distillation is desired the action of the apparatus is as follows.--
The liquid traversing either the inside or the outside of the tubes, being acted
upon by the steam on the reverse side, becomes distilled or evaporated as it passes
down the tubes in a filin, the rate of the flow of the liquid being regulated by a valve.
The pressure and temperature being also under control the liquid may be evaporated
at any desired pressure and temperature varying from that of a vacuum or nearly
so to any desirable pressure above that of the atmosphere. The distillate is con-
densed by the condenser working in conjunction with the evaporator, and the
temperature at which the distillate is condensed may be regulated by the quantity and
temperature of the condensing water used. The condenser may be constructed like
the evaporator, a greater quantity of water being employed.
When the multiple system of evaporation is adopted and economy of heat is
desired then two or more evaporating chambers in conjunction with the condenser,
refrigerating apparatus and the necessary liquor and vapour mains and chambers
and other appurtenances may be worked in the tollowing manner :-The initial
steam being supplied from the boiler or generator to the stean passages of the
first vessel and the liquid to be distilled being fed to the evaporating surfaces of

page_text: the tubes, the steam becomes condensed on the steam side while a fresh evapora-
tion takes place on the liquor side as the liquid descends in a film on its passage
from the top to the bottom of the tubes, the steam generated from the liquor side
passing into the steam passages of the next evaporating vessel, and so on throughout
the series. The liquid remaining over may pass on to the next vessel or vessels
in succession when the number of distillations or evaporations is not very many, and
the pressure between vessel and vessel is more than sufficient to oppose the columnar
pressure exerted by the liquid in passing from the bottom of one vessel to the top of
the next. When a great number of distillations or evaporations are desired then
the liquid may be supplied as before explained to a group of vessels and thence
onwards to the other groups in succession, steam traps or pumps being supplied
to limit the escape of vapour to that contained in the fluid. The vapour from the
last vessel being condensed by the condenser and removed by a pump or other suitable
means the condensed liquid and the residuary liquid being cooled by the refrigerating
apparatus, the in-flowing liquor being the cooling medium, the heat is economized to
the full.
The construction of the vessels must obviously be modified to suit the purpose for
which they are intended, whether for water, fresh or salt, or for syrups, sugar liquors,
dyes, ammoniacal liquors, alkalies, acids or salts, the apparatus being also made of a
suitable material for the purpose for which it is to be used.
To provide against extraordinary cases or against radiation or loss of heat, or
to drive out the air in starting the apparatus, the steam should be connected or laid
on from the generator to the vessels. Drain cocks and other necessary appurtenances
may be provided for the vessels and mains; baffle plates may be used in the chambers
or suitable contrivances to deglobulate the vapour in case of priming or overboiling
and circulating pumps can be employed when necessary.
Although we have described our invention as applied to the evaporation or distilla-
tion of liquids it can also be applied to other purposes where the interchange of heat
is required such for example as refrigeration and condensation. When the apparatus
is employed as a condenser and is constructed with an internal tube (such as herein-
before described to act as a steam space) this tube need not be perforated; or it may
be dispensed with, and the jacketted tube may be a spirally twisted tube instead of a
plain tube with spiral metal pieces thereon.
Dated this 15th day of July 1889
J. C. MEWBURN,
55 & 56, Ohancery Lane, London, Patent Agent.
COMPLETE
SPECIFICATION.
Improvements in Apparatus for Evaporating or Distilling or
Effecting Interchange of Heat
Wo RICHARD CHARLES GARTON and CHARLES HENRY GARTON both of South-
ampton Wharf, Battersea in the County of Surrey, Brewers and WILLIAM LAWRENCE
of 22 St. Mary Axe in the City of London, Brewer's Engineer, 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 has reference to apparatus for evaporating or distilling or effecting
interchange of heat. The improved apparatus comprises an arrangement or set of
vessels each containing one or more tubes or cylinders and so placed with regard to
each other that the liquid to be evaporated, heated or cooled and the heat employed
in the evaporation or heating may be dealt with in the most satisfactory or
advantageous manner and with great economy of fuel.
The vessels are arranged so that the tubes contained in them are vertical or nearly
so and the liquid to be evaporated flows down the tubes, generally in a film,
on the one side, while the steam or heating medium is acting upon the reverse
side.

page_text: In some cases it is intended that the vapor generated in one vessel shall form the
heating medium for the next and so on throughout the series.
In other cases it is intended that the steam generated from a group of vessels or
from two or more vessels shall be the heating medium for the next group or set of
vessels and so on.
In other cases it is intended that one or more vessels shall be supplied singly or
separately with steam direct from the generator.
The steam or heating medium is supplied to the apparatus at pressure either above
or below that of the atmosphere, or it may be the waste steam from engines, and in
such case the apparatus may act as a surface condenser.
In some cases the liquid to be evaporated is intended to be supplied from one vessel
to another in succession. In other cases the liquid to be evaporated is intended to
be supplied from one group of vessels to another group of vessels in succession. In
other cases also the liquid is intended to be supplied separately or to each vessel and
not in succession.
The tubes may be cylindrical or truncated cone shaped and are spirally twisted or
they are grooved, corrugated or channelled spirally or laterally, so that the liquid
whilst being evaporated is caused to traverse a greater distance than if traversing the
walls of a plain cylinder, or they are fluted, grooved or channelled longitudinally so
as to facilitate the evaporation of the liquid under treatment.
It is intended generally to use a condenser attached to or in combination with the
last vessel of the set to condense the vapor from the last evaporation; such condenser
may be a surface condenser or an ordinary jet condenser, or a condenser such as the
evaporating apparatus herein described.
When only one evaporation is desired then the apparatus is made to consist of a
single evaporating vessel and a condenser as previously named, and the necessary
attachments for steam and liquid and other requisites.
When the redistillation or inore than one evaporation of the liquid or the economy
of heat is desired, then the apparatus is made to consist of a number of vessels in
which one or more vessels act as the condensers for one or more vessels of the previous
vessel or set. In such case a condenser is only needed to condense the vapor arising
from the last vessel or set. In this case the apparatus also includes an arrangement
of a liquor supply main or mains and a condensed liquor main or mains, so
constructed as to pass onwards to the next vessel or vessels in succession the liquid
together with the vapor arising from such liquid.
It must be borne in mind that the pressure and temperature of the liquid and vapor
in the first vessel will be higher than the next and so on, and that the liquid on
escaping from each vessel will give off vapor. This vapor must not be lost but must
be passed on to the next vessel or vessels in succession; otherwise during a great many
transmissions the whole of the original heat units may be lost. It will also form a
part of this arrangement to employ cooling apparatus for both the condensed liquid
and for the residuary liquid not distilled. A suitable apparatus to cool the condensed
liquid, it not being of a corroding nature, is a vessel identical with the evaporating
vessel where only one tube is encased; the condensed liquid would flow upwards
between the jacket and the tube, while the liquor to be heated would flow inside
the tube.
To cool the residuary liquid any suitable refrigerator may be used, care being taken
to provide against corrosion.
In the construction of the apparatus the vessels containing the tubes are sometimes
provided with a top and bottom tube plate and sometimes with a bottom tube plate or
one tube plate only, such tube plate or plates being affixed to a suitable chamber or
chambers for the reception of the vapors and the liquids that are being condensed and
distilled. The tubes may be fixed into the tube plate by an expanding mandril or in
any suitable way.
When the liquid flows inside, the tubes should have both a top and bottom tube
plate. A distributing arrangement is also provided for supplying the tube or tubes
with a feed regulation. Removable doors and covers are also provided for cleaning

page_text: out and otherwise gaining access to the tubes. Sight holes, man holes and steam
traps are also provided.
When the liquid is arranged to flow externally either one plate or a bottom plate
or top and bottom plates are employed. If only one plate is used a removable cover
may form part of the jacket or chamber. In such case the liquid may be delivered
to the distributing feed arrangement attached to the top of the pipes by means of a
stand pipe through which the liquid will be conveyed through or from the bottom of
the vessel. If top and bottom plates be used, then the jacket or casing not being
removable will require to be of sufficient size and furnished with a mau hole to
allow of a man entering for cleaning or other purposes. Sight holes and steam traps
should also be provided.
When a single distillation is desired the action of the apparatus is as follows, The
liquid traversing either the inside or the outside of the tubes being acted upon by the
steain on the reverse side becomes distilled or evaporated as it passes down the tubes
in a filin, the rate of the flow of the liquid being regulated by a valve. The pressure
and temperature being also under control the liquid may be evaporated at any
desired pressure and temperature varying from that of a vacuum or nearly so to any
desirable pressure above that of the atmosphere. The distillate is condensed by the
condenser working in conjunction with the evaporator, and the temperature at which
the distillate is condensed may be regulated by the quantity and temperature of the
condensing water used. The condenser may be constructed like the evaporator a
sufficient quantity of water being employed.
When the multiple system of evaporation is adopted and economy of heat is
desired then two or more evaporating chambers in conjunction with a condenser, a
refrigerator and the necessary liquor and vapor mains aud chambers and other
appurtenances may be worked in the following manner :-The initial steam being
supplied from the boiler or generator to the steam passages of the first vessel and the
liquid to be distilled being fed to the evaporating surfaces of the tubes, the steam
becomes condensed on the steam side while evaporation takes place on the liquor side
as the liquid descends in a film on its passage from the top to the bottoin of the
tubes, the steam generated from the liquor side passing into the steam passages of
the next evaporating vessel and so on throughout the series. The liquid remaining over
may pass on to the next vessel or vessels in succession when the number of distillations
or evaporations is not very many, and the pressure between vessel and vessel is more
than sufficient to oppose the columnar pressure exerted by the liquid in passing from
the bottom of one vessel to the top of the next. When a great number of distillations
or evaporations are desired then the liquid may be supplied as before explained to a
group of vessels and thence onwards to the other groups in succession, steam traps or
pumps being supplied to limit the escape of vapor to that contained in the fluid. The
vapor from the last vessel being condensed by the condenser and removed by a pump
or other suitable means the condensed liquid and the residuary liquid being cooled by
the refrigerating apparatus, the in-flowing liquor being the cooling medium. In this
way heat will be economized.
The construction of the vessels must obviously be modified to suit the purpose for
which they are intended, whether for water, fresh or salt, or for syrups, sugar liquors,
dyes, amoniacal liquors, alkalies, acids or salts, the apparatus being also made of a
suitable material for the purpose for which it is to be used.
To provide against extraordinary cases or against radiation or loss of heat, or to
drive out the air in starting the apparatus, the steam should be connected or laid on
from the generator to the vessels. Drain cocks and other necessary appurtenances
may be provided for the vessels and maius; baffle plates may be used in the chambers,
or suitable contrivances to deglobulate the vapor in case of priming, and circulating
pumps can be employed when necessary.
Although we have above described our invention as applied to the evaporation or
distillation of liquids it can also be applied to other purposes where the interchange of
heat is required, such for example as refrigeration and condensation. When the
apparatus is employed as a condenser means are adopted to control and regulate the

page_text: flow of water and there may be a limited orifice for each tube. When, however,
the tubes are small as may be the case for condensers where space is an object the full
bore of the tubes may be employed and then no special feed arrangement is required.
The position of the apparatus as a condenser is by preference vertical or nearly so but
it may be horizontal, though the tubes in such case become more readily coated with
sedimentary matters.
The accompanying drawings represent various forms of apparatus constructed
according to this invention.
Figures 1 and 2 are respectively an elevation and a plan both partly in section of a
still or evaporator in which spirally twisted tubes are employed, the liquid to be
distilled or evaporated being caused to flow in a thin film down the inside of these
tubes. is the outer vessel, g the inlet for the steam or heating medium to same, b the
inlet pipe for the liquid and the outlet pipe for that portion of the liquid which is
not evaporated; the liquid is drawn away by means of a pump or is regulated by a
valve if the distillation is carried on above the pressure of the atmosphere; is the
outlet for condensation water. a, a are the spirally twisted tubes connected to top
and bottom tube plates k, k¹. is a pipe for conducting to the upper chamber m of
the vessel such portion of the steam or vapor as issues from the bottom of the
tubes . 12 the outlet for the vapor to the condenser, which may be a vessel of
similar construction to the still as regards the tubes and tube plates or it may be of
other suitable construction.
Figure 3 shows on a larger scale the upper part of some of the twisted tubes a and
the means of feeding them with liquid in a film. The heads of the tubes above the
plate k have movable or fixed tabular continuations q open at top and having feed
slits d, & punched or cut in them so as to leave projecting baffle or guide pieces-
see the sectional view Figure 4; the liquid which is supplied by the pipe b,
Figure 1, surrounds these continuations 9 and flows through the slits d so as to enter
the tubes a.
Figure 5 represents an apparatus suitable as a surface condenser more especially
for marine purposes. The cold water enters through the pipe b into the space or box
between the plates k and 2 from which it flows through the slits d into the con-
tinuations of the spirally twisted tubes a. The steam to be condensed enters the
chamber or jacket i surrounding the tubes. Around the lower end of the water inlet
pipe is a stand pipe 12 open at both ends. When the pitching or rolling of the ship
is considerable the water passes up between the pipes b and b². In this way the
equal hollow flow of the condensing water is cusured on a rolling sea, the stand pipe b
being carried sufficiently high to maintain the water supply to the water box between k
and . The arrangement shown is, however, not always necessary in cases where
space is an object and the tubes must be of small diameter. The full bore of the tube
is required for supply where small tubes are placed vertically or nearly so and their
length is so proportioned to their diameter that the entire bore supplies only so much
water as is necessary either by natural flow or by a force pump. Feed tubes are also
unnecessary when the water is made to pass upwards and to flow out at the top; in
such case also the tubes need not be small, but the twists or corrugations or flutings
inust be so formed on them as to give the greatest mobility to the water against their
acting surfaces. Feed tubes are also unnecessary when the flow of water is downwards
and the outflow from the condenser is restricted or fitted with a regulating valve.
This downward flow is preferable as preventing sedimentary deposit; also with the
usual doors or covers provided it gives facility for brushing out the tubes. The
vertical form also is advantageous in supporting the tubes and taking off the weight
of the water from the tubes which in ordinary plain tube condensers placed
horizontally causes the breaking of the tubes. The spiral or corrugated tube con-
denser is not liable to this inasinuch as the elasticity given to the tubes prevents them
becoming strained. Another great advantage of this form of condenser is that the
inducing of the greatest possible mobility of the water against the surfaces permits the
use of condensing water at a higher temperature and gives facilities for obtaining a
high vacuum on tropical seas. The twisted tube condenser may be placed horizontally

page_text: when the twists are very sharp, but the tendency to sedimentary deposit interferes
with the action of corrugated or slower twisted tubes when they are horizontal. When
the condenser tubes are arranged vertically or approximately so, and the liquid flows
through the same in full bore, the corrugations can be lateral that is to say at right
angles to the plane of the axis of the tube instead of being spiral, in this case some
of the water in passing down the tubes will tend to flow round the corrugations and
to form eddies therein and the effectiveness will be thereby increased.
The arrangement shown in Figure 5 is also applicable as a refrigerator; in this
case the stand pipe 62 will not be required. The liquid to be refrigerated or cooled
is supplied to the outer case i while the refrigerating or cooling liquid is supplied
to the tubes a or vice um 806.
Figure 6 is an elevation partly in section of a distilling or evaporating apparatus
constructed according to our invention in which the liquid flows outside the tubes.
Figure 7 is a view on a larger scale showing some of the tubes and their feeding
arrangement. Similar letters to those in Figure 1 indicate corresponding parts. The
liquid is shown as entering the lower part of the evaporating vessel by the pipe b which
carries it up through the middle of the vessel so as to discharge into the trough c
above the tubes ; from this trough it passes in films through the annular openings d
so as to reach the exterior of the tubes down which the films flow.
3, are a series
of conical frustums surrounding the set of tubes for the purpose of baffling and
thereby deglobulating the steam or vapor evolved from the liquid. The steam is
supplied to the vessel i by the pipe g and entering the bottom of the tubes a passes
up the saine so as to heat them internally. The tubes are closed at top except that
there is an air pipe. The liquid which reaches the bottom of the tubes without being
evaporated collects on the bottom tube plate 1 and passes through the pipe f to the
next evaporating vessel (when there is one) while the steam or vapor evolved from
the liquid passes through the pipe g' for use in the next vessel on the multiple effect
system or to a coudeuser where there is not another vessel. The outer vossel i is
removable at the flangest without breaking the joint of the pipe g¹.
Figures 8 and 9 are respectively an elevation and a plan both partly in section of
an apparatus in which the liquid to be evaporated flows outside the tubes and which
differs from the apparatus shown in the previous figures in being rectangular and in
having a steam box at bottom from which the steam is admitted to the tubes, the
steam after passing upwards through some of the tubes traversing D-shaped con-
necting pieces or bends and then passing down others of the tubes, the tubes being
connected in pairs by the D-pieces. is the steam inlet, wo the steam box divided
by a vertical partition x with a hole x¹ cominunicating between the two compartiments
of the box. 3, y are the D-pieces connecting the tubes a, a in pairs. Other letters
indicate parts corresponding to those similarly lettered in the figures previously
described.
Figure 10 is a plan of an apparatus somewhat similar to that shown in Figures 8
and 9 but with the spirally twisted tubes a for the upflow of the steam arranged in a
circle and with the spirally twisted tubes for the downflow of the steam arranged in
a concentric circle (or it might be outside) the first circle of tubes. Each tube of
the one circle is connected at top by a bend or elbow piece y to the top of an adjoin-
ing tube of the other circle. The tubes of the outer circle connected at bottom to
in annular steam supply box to while the tubes of the inner circle are connected at
bottom to another annular box w¹.
When it is for any purpose required to employ spiral tubes of comparatively large
liameter it is difficult to spirally twist them, and in this case we can form what is
practically a twisted or spiral tube by arranging a number of plain tubes in a circle,
hese tubes being each given a spiral bend not on its own axis but on the axis of the
whole body or circle of tubes as shown in Figure 11; the combination of the tubes
produces a large tube or cylinder with spiral ways both externally and internally.
With this arrangement the liquid to be evaporated is caused to flow in a film down
both the outside and inside walls or down either the outside or the inside wall of this
arge tube or cylinder while steam is admitted to the tubes of which the large tube or

page_text: cylinder is composed. The combination shown in Figure 11 can be modified by making
the tubes a straight and of circular, oval or other section, that is to say a number of
straight tubes supplied with steam can be arranged in a circle so as to form a large
tube or cylinder which will have longitudinal channels formed between the surfaces
of the various tubes of which it is composed. The liquid to be evaporated would
flow in a film down these channels.
Figure 12 represents in elevation partly in section a quintuple effect apparatus in
which the liquid is evaporated on the outside of spirally twisted tubes and is fed
separately to each evaporating vessel while the steam or vapor evolved from the
liquid in one vessel passes on to serve as the heating medium in the next vessel.
Letters corresponding with those in the previous figures indicate corresponding parts.
The liquid to be evaporated is supplied from a main b¹ to the separate feed pipes b of
the five evaporating vessels and enters each of these vessels above the plate k from
which it flows in films through annular openings as in Figure 7 to the outside of the
spirally twisted tubes a. The steam is supplied to the top of the first vessel by
the pipe g and passes down through the interior of the tubes a in this vessel;
the condensation water passes off from the bottom of this vessel through an ontlet /
into the condensation main h'; the stean or vapor evolved from the liquid in the
first vessel passes by the pipe g' to the next vessel. Any liquid that reaches the
bottom tube plate unevaporated passes off through the pipe finto the main f¹.
In the arrangements hereinbefore described in which steam or vapor enters the
tubes at the one end and the other end of these tubes is closed, they should be fitted
with air pipes, and when the vapor evolved from the liquid in one vessel is not passed
to another vessel on the multiple effect system the air pipes from a number of tubes
may terminate in a common box from which a pipe is carried to the outside of the
apparatus. Or the tubes may have internal air tubes leading from near the closed
end to a general outlet.
In all the arrangements illustrated in Figures 1 to 12 the tubes are shown with
spiral twists, flutes, grooves or channels and this spiral form is what we prefer. Our
invention, however, includes the use of longitudinally fluted, grooved or channelled
tubes in apparatus working either above or below atmospheric pressure and whether
on the multiple effect system or not, and whether the film evaporation be produced on
the outside or the inside of the tubes. The grooves, flutes &c. whether spiral or
longitudinal possess a great advantage over plain or smooth surfaced tubes when used
for film evaporation. Liquids can be evaporated upon the thin film principle more
readily than when treated in the bulk, because aqueous liquids are bad conductors of
heat. Therefore, however good a conducting heating metallic surface may bo
employed, the aqueous liquid being acted upon, if not instantly and continuously
removed from the heating surface will obstruct and interfere with the conductive
If the act of ebullition is to be made the motive power for
power of the metal.
removing the heated liquid, then the liquid must become violently agitated by
ebullition before the conductive action can be fully set up. But when the descent of
the fluid by gravitation is employed as the agent for removing the heated liquid, then
the transmission of heat no longer depends for acceleration upon the action of
ebullition and it becomes possible to transmit the heat from one side of the metallic
But such result
surface to the other as fast as the heat will traverse the metal.
cannot be satisfactorily brought about by an ordinary plain tubular surface even with
film evaporation which was attempted before the date of our application for patent.
A plain surface will not fulfil the conditions required. In the first place it is not
practicable to secure evenness of flow down a plain surface. A twisted or spirally or
longitudinally grooved tube on the other haud meets the difficulty. In addition to
this the surface when spiral gives a greater distance of traverse for the liquid and
therefore a greater mobility upon the heating surfaces, thereby rendering them more
effective. Beyond these advantages there are others of great importance in the
evaporation of viscous liquids which overcome the difficulty arising from bubbles
forming upon and throwing out of use, the heating surface when evaporation is being
conducted upon the thin film principle. It will be readily understood that wherever

page_text: bubbles form upon the heating surface such surface becomes for the moment
inoperative and not only so, but the high temperature of the heating medium will
instantaneously affect the liquid, a fine film of which will remain upon the surface
and be left adhering to it and in the case of liquids such as saccharine solutions,
become charred more or less. In the employment of plain surfaces this difficulty
arises for the reason that the liquid in descending in a film becomes evenly heated
and commences to boil at a short distance from the top of the tubes, and a point is
soon reached where the bubbles or bladders that form upon the surface prevent the
descending liquid from touching the heating surface, a considerable portion of which
is thereby thrown out of use. Now by the substitution of spirally twisted or spirally
or longitudinally grooved tubes for plain tubes the act of ebullition does not throw
the surface out of use, because the whole of their heating surfaces are fed with liquid
which flows down the channels in a liquid form and small bubbles only form upon the
edges of the channels; thereby a perfect ebullition is set up from one end of the tubes
to the other (or from top to bottom of the tubes).
The diameter and the particular kind of channelling or grooving of the tubes can
be varied as thought best according to the purpose for which the apparatus is required
and the special form of the apparatus. We have found that when the liquid is very
viscons and liable to set up a bubbling action the spiral twists are best made at an
angle of about 45°, the indentations or channels being largest on the outside surface
of the tubes (like the grooves of a screw) for the outside flow of the liquid and that
when it is wished to retard the travel of the liquid a slower twist or one less than an
angle of 45° is preferable. The diameter of the tube should be chosen according to
the general considerations. We have found tubes of from one and a half to about
five inches to answer well for outside evaporation. The same observations are applicable
as regards deciding upon the most advantageous tubes for inside flow of the liquid,
but in this case the indentations or channels should be largest on the inside surface.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that we do
not claim as part of this invention anything that is claimed in either of our
Specifications Nos. 83 and 11350 of 1889 but what we claim is :-
:-
1. In distilling or evaporating apparatus working above or below atmospheric
pressure and not on the multiple effect system, the combination with an outer vessel
or jacket supplied with steam or vapor, of inner tubes which are spirally twisted or
spirally or longitudinally grooved or channelled and of means whereby the liquid to
be distilled or evaporated is made to flow down in films against the inner walls of the
inner tubes, substantially as set forth.
2. In distilling or evaporating apparatus working above or below atmospheric
pressure and not on the multiple effect system, the combination with tubes which are
spirally twisted or spirally or longitudinally grooved or channelled and are supplied
with steam or vapor, of means whereby the liquid to be distilled or evaporated is
made to flow down in films against the outer walls of the tubes, substantially as set
forth.
3. In distilling or evaporating apparatus working on the multiple effect systein, the
combination with outer vessels or jackets of inner tubes which are spirally twisted or
spirally or longitudinally grooved or channelled and are supplied with steam or
vapor, and of means whereby the liquid to be evaporated is made to flow down in
films against the outer walls of the tubes, substantially as set forth.
4. In distilling or evaporating apparatus working on the multiple effect system, the
combination with outer vessels or jackets supplied with steam or vapor, of inner
tubes which are longitudinally grooved or channelled and of means whereby the
liquid to be distilled or evaporated is made to flow down in films against the inner
walls of the inner tubes substantially as set forth.
5. The particular arrangements of apparatus whether worked above or below
atmospheric pressure, represonted respectively in Figures 1 to 4, Figures 6 and 7,

page_text: Figures 8 and 9, Figure 10, Figure 11 and Figure 12, in which the liquid to be
distilled or evaporated is caused to travel in thin films down spiral ways of evaporating
tubes as set forth.
6. In a condenser, an outer jacket for the steam or vapor in combination with
inner tubes for the condensing liquid which inner tubes are spirally twisted or spirally
grooved or corrugated, substantially as set forth.
7. In a condenser, an outer jacket for the steam or vapor in combination with inner
tubes for the condensing liquid which inner tubes have lateral corrugations substantially
as set forth.
8. In a refrigerator, an outer jacket for the liquid to be refrigerated or cooled or
for the refrigerating or cooling liquid in combination with inner tubes for the
refrigerating or cooling liquid or for the liquid to be refrigerated or cooled, which
inner tubes are spirally twisted or spirally or laterally grooved or corrugated,
substantially as set forth.
9. The particular construction of condenser substantially as represented in Figure 5
and hereinbefore described.
Dated this 6th day of May 1890
J. C. MEWBURN,
55 & 56, Chancery Lane, London, Patent Agent.