IMPROVEMENTS IN EVAPORATION
Year: 1826

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
WILLIAM CLELAND, of the City of Glasgow, Gentleman, send greeting.
WHEREAS His most Excellent Majesty King George the Fourth
did, by His Letters Patent under the Great Seal of the United King-
dom of Great Britain and Ireland, bearing date at Westminster, the
Twenty-fourth day of July, One thousand eight hundred and twenty-
six, in the seventh year of His reign, give and grant unto me, the said
William Cleland, my exors, adññiors, and assigns, His especial licence,
full power, sole privilege and authority, that I, the said William
Cleland, my exors, adñiors, and assigns, during the term of years therein
mentioned, should and lawfully might make, use, exercise, and vend,
within England, Wales, and the Town of Berwick upon Tweed, and
also in all His Majesty's Colonies and Plantations abroad, my Inven-
tion of "IMPROVEMENTS IN EVAPORATION," in which said Letters Patent
there is contained a proviso, that if I, the said William Cleland, shall
not particularly describe and ascertain the nature of my said Invention,
and in what manner the same is to be performed, by an instrument in
writing under my hand and seal, and cause the same to be inrolled in
His Majesty's High Court of Chancery within six calendar months
next and immediately after the date of the said Letters Patent, that

page_text: then the said Letters Patent, and all liberties and advantages whatsoever
thereby granted, shall utterly cease, determine, and become void, as in
and by the same, relation being thereunto had, will more fully and at
large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the
said William Cleland, do hereby declare that the nature of my afore-
said Invention of improvements is herein-after particularly described
and set forth (that is to say):
It consists of two separate parts or processes, the first of which
may be used separately or conjointly with the second, or not, as circum-
stances will permit or require. The first part of my Invention consists
in a certain manner of causing a rapid current of heated or cold air to
pass over the surface of the fluid or solution which is required to be
evaporated, in such manner as to cause a more than ordinary quantity
of such fluid or solution to come into contact with such air, which will
thereby become charged or loaded with the steam or vapour of such
fluid, and will thereby be considerably heated whenever such air is
admitted at a temperature much below such fluid. And the second part
of my said Invention is the use that I make of such current of air after
it has been so heated, and has combined with the hot vapour as afore-
said, for heating or raising the temparature of a second or other quantity
of fluid for the purpose of evaporating it, or for any other purpose, by
which means the caloric so obtained by the air is not wasted or dis-
sapated, but is communicated to such second portion of fluid, and is
thus made to perform two or more successive useful and economical
operations.
From the nature of my Invention it is applicable to boilers of
various forms and dimensions, and I do therefore not restrict myself
to any particular form, shape, or dimensions of boiler or furnace for
heating the same, either for the first or second parts of my Invention;
I shall therefore describe the principles upon which my said improve-
ments depend, and the circumstances which must be attended to
for producing the full effect of my Invention, and I shall afterwards
explain one of the many forms or constructions of which those
principles when conjoined are susceptible. For example, suppose an

page_text: evaporating pan or copper of any kind (but the more surface it exposes
the better) to be set in the usual or accustomed manner with a fire
place underneath it, or any of the usual and customary means of supply-
ing heat for boiling or evaporating fluids according to the temperature
they may require or be able to sustain; this will be the usual and
accustomed apparatus for evaporation, in which the surface of the fluid
is generally exposed to the open air to promote the effect. So far,
therefore, I make no claim to the apparatus and process above mentioned,
(except only so far as the same is used in combination with my Inven-
tion and improvements about to be described); instead, however, of using
the said apparatus or evaporating pan in its usual open and exposed
state, I box in or enclose the upper part of the said pan in a close
case of wood or metal in the nature of a chest, which by preference I
make square, tho' any other form will do. This casing must be toler-
ably air and steam tight in every part except its front, where I form an
opening of six or eight inches in height, and extending quite across the
front of the said chest or covering from one side to the other in an
horizontal direction, for admitting the air that is to produce the evapora-
tion of the fluid; and on the opposite side of the said chest or covering
a similar hole is made for the escape of such air into a flue or pipe of
sufficient height to produce a rapid draft after it has performed its
office. This flue is not, however, in all cases necessary, as will afterwards
appear, and when it is constructed in the simple form above mentioned
it may be made of boards, there being no fear of its ignition, since
nothing but heated air and steam ever passes up it. I likewise fit a
door which slides up and down, or some other similar contrivance, to the
front opening by which the air enters, and by means of which I can
regulate the stream of air to any thickness from the full heigth of the
opening to half an inch or less, while such stream of air is always left.
of the full width or extent of the casing, and thus any quantity of air
may be admitted which experience proves to be best for the operation.
On the top of the casing I construct a water-tight reservoir formed by
the perpendicular extension of its own sides above the top; such reser-
voir will consequently be of the same dimensions as the horizontal
section or plan of the casing, and need only be a few inches deep, or if

page_text: the pan is small it may be larger or less to suit convenience, and it may
be open or exposed to the air above or otherwise; and across the central
or other part of the bottom of this reservoir, and extending from one side
to the other in the same direction as the air passages, I bore a number of
small holes, or let in a metal plate pierced with small holes, which plate
may be from six to twelve inches or more wide, thus forming a part of the
bottom of the reservoir into a kind of cullender. I moreover fix a pump
of the common construction for hot liquors, and of a sufficient stroke and
diameter to suit the magnitude of the apparatus, either through the
bottom of the said reservoir or by the side of it, on the outside, in such
manner that the said pump when worked may draw the hot liquor out
of the ordinary boiler or copper below, and deliver it into the reservoir,
from which it runs away through the holes or cullender back into the
first boiler again, being first minutely divided into a kind of shower by
the holes or cullender, and in which divided state it passes through
the perpetually changing sheet or current of air produced as aforesaid.
It will therefore be evident that by this improved process I not only
obtain the usual quantity of evaporation that would take place from a
common boiler, but a greatly increased evaporation, from the very large
surface of fluid that is exposed in the shower to a more than ordinary
quantity of fresh air brought in and kept in motion by the means before
described. If, however, I find it necessary to produce a still greater
rapidity of evaporation, I do this by constructing a cast iron r other
air chamber round the fire that heats the boiler below, and I supply
this chamber with fresh air from below, and carry the air when it is so
heated and dried by a close tube or tubes to the long opening or orifice
herein-before described, by which the air enters the chest or inclosure,
or I heat such air by a separate fire or by steam, or in any of the well
known and accustomed methods; but I do not consider such heating
of the air as any part of my Invention, air having been heated before
in many ways; and all that I claim is, therefore, the introduction as
aforesaid of air heated and dried by any process into the chamber or
casing, as before described, to produce the effect aforesaid.
In the above description the heated air so introduced into the case or
chamber, or the cold air that will become heated by contact with the hot

page_text: fluid and admixture with its steam is described as being dissapated and
thrown away by passing up a flue. But the second part of my Inven-
tion relates to the economy of that heat, and the conversion of it to a
useful and beneficial purpose. To produce this end instead of letting
the said hot and moist air and steam pass away up the flue or chimney
herein-before described as being contiguous to the back opening of the
chest or covering of the boiler, I cause such back opening to commu-
nicate with an horizontal or other fluc or tube, which will be best made
of metal on account of its power of conducting heat rapidly, and I
conduct this last-mentioned tube or flue either through or underneath
the bottom or round the outside of one or more boilers or pans placed
or set in a convenient position for such purpose, and I cause the
extreme end of such flue to turn upwards for a sufficient distance to
produce the requisite draught and consequent motion of the sheet of
air. In this way sufficient heat will be communicated to such lateral
boilers or pans to commence the process of evaporation, or to prepare
the fluids they contain for removal into the first-mentioned main evapo-
rating pan, instead of introducing them in a cold state into the same,
whereby much fuel will be saved. Where still more heat may be
required than can be obtained by the last described process I cause
the flue or chimney of the fire-place or furnace, herein-before men-
tioned as being placed under the first or main evaporating pan, to run
and be continued either in an horizontal or other more convenient
direction under the bottoms of, or in contact with, or turning round the
sides of one, two, or more boiling or evaporating pans (the number of
such pans being limited by their magnatude and the heat required in
them), and I make the end of such flue or chimney to point upwards to
a sufficient heighth to produce the draft that should be necessary to
cause the fire to burn with proper activity under the first or principal
pan; and I moreover cause the back air opening of my aforesaid chest
or cover for the said principle pan to turn downwards and communicate
by means of a brick or other tube or funnel (which should be formed of
materials which conduct heat badly) into the said smoak flue of the
said fire-place, so that the sheet of air heated and combined with steam
as aforesaid may pass off and mix with the smoak and hot air coming

page_text: from the fire, by which a rapid current or draft of such air through the
chest or covering of the first or principal pan or boiler will be insured,
and the heat which such air has derived from the fluid under evapo-
ration in such pan or boiler will go in aid of the heat produced by the
fire for heating the secondary pan or pans, and the fluid or materials
they may contain, either for evaporating them, preparing them for
evaporation, or any other purpose.
In the several modifications above described of my said Invention,
it will appear that the current of air through the covering chest
of the first or principle boiler is produced by the agency of a particular
flue in which such air will rise on account of its specific levity pro-
duced by its being heated and mixed with steam, or else by carry-
ing that air and steam into the smoak flue of the fire, and taking
advantage of the stronger draft which will there exist to produce a
more rapid motion. But inasmuch as the main principle of the first
part of my Invention is the exposure of a more than ordinary portion
of the surface of the fluid under evaporation to the action of a con-
stantly changing stream or current of air, either its common or in a hot
and dry state, and the division of the fluid into a shower of drops or
minute streams, by the means aforesaid, or by letting the hot fluid run
from one level to another without the use of a pump or pumps, and
permitting it to pass through one or more cullenders or reservoirs
pierced with holes as aforesaid, and leaving a current of air passing
under the bottom of each of them, so I hereby claim and consider the
production and use of that current of air, whether the same be produced
in the nature and form of a sheet, which I consider the best, or in any
other form, so that it meets with and comes in contact with the shower
of fluid, or that the two mutually incorporate and pass each other, to be
the essence and spirit of the first part of my Invention; and I therefore
claim every form and modification of apparatus and machinery by which
the said effect may be brought about, whether such current of air be
produced by bellows or other blowing machinery, or by mechanical
exhaustion or rarification of the air to be carried away, instead of
removing it by a natural draft, as herein-before described. The height
of the shower, or, in other words, the height of the cullender or strainer

page_text: above the surface of the liquid under evaporation in the pan, must be
regulated by the size of the pan and the nature of the fluid under
operation; but in all cases it should be as high as it can be made
without producing inconvenience by splashing. Lastly, I hereby
declare that I do not claim the application of heated air, or of air.com-
bined with steam, or of steam alone, to the purpose of heating the
secondary pans above described, or for any other purpose of producing
heat, as any part of my Invention, unless when such heated air is
produced by the use and application of the said first part of my In-
vention, the spirit and essence of the second part of my Invention
being that of appropriating the hot air mixed with steam which is
produced by the first part of my Invention to a useful and beneficial
purpose, by causing it to give back the heat or caloric which it has
imbibed from the fire and liquid under evaporation, instead of per-
mitting that heat to be dissipated in a useless manner in the at-
mosphere, and by which means the same quantity of caloric is made
to perform two or more successive operations, as before mentioned.
In the construction of my aforesaid apparatus, I avail myself of all
necessary dampers, valves, or other contrivances for regulating or
shutting in part or wholly the said chimneys or air passages, and thereby
regulating the strength of the fire or the velocity of the currents of
air, but as these form no part of my Invention, and their use and appli-
cations will be obvious to every one, I do not think it necessary to
describe them.
In witness whereof, I, the said William Cleland, have hereunto
set my hand and seal, this Twentieth day of January, in the
year of our Lord One thousand eight hundred and twenty-
WILLIAM CLELAND. (L.S.)
Signed, sealed, and delivered by the within-
named William Cleland, in the presence of
Tuo. WATSON,
Sol, Bristol,

page_text: AND BE IT REMEMBERED, that on the Twentieth day of
January, in the year of our Lord 1827, the aforesaid William
Cleland came before our said Lord the King in His Chancery, and
acknowledged the Specification aforesaid, and all and every thing
therein contained and specified, in form above written. And also the 5
Specification aforesaid was stamped according to the tenor of the
Statute made for that purpose
Inrolled the Twenty-fourth day of January, in the year of our
Lord One thousand eight hundred and twenty-seven.