IMPROVEMENTS RELATING TO THE APPLICATION OF ATMOSPHERIC AIR FOR PREVENTING THE WASTE OR LOSS OF HEAT IN PROCESSES AND APPARATUS WHEREIN HEAT IS GENERATED OR UTILIZED, AND FOR PREVENTING THE ENTRANCE OF HEAT INTO PROVISIONAL SPFICATION
Year: 1875

page_text: LETTERS PATENT to Edwin Maw, of Liverpool, in the County of
Lancaster, Civil Engineer, for the Invention of "IMPROVEMENTS
RELATING TO THE APPLICATION OF ATMOSPHERIC AIR FOR PREVENTING THE
WASTE OR LOSS OF HEAT IN PROCESSES AND APPARATUS WHEREIN HEAT IS
GENERATED OR UTILIZED, AND FOR PREVENTING THE ENTRANCE OF HEAT INTO
PROVISIONAL SPECIFICATION left by the said Edwin Maw at the
Office of the Commissioners of Patents, with his Petition, on the
25th October 1875.
I, EDWIN MAW, of Liverpool, in the County of Lancaster, Civil
Engineer, do hereby declare the nature of the said Invention for
" IMPROVEMENTS RELATING TO THE APPLICATION OF ATMOSPHERIC AIR FOR
PREVENTING THE. WASTE OR LOSS OF HEAT IN PROCESSES AND APPARATUS WHEREIN
HEAT IS GENERATED OR UTILIZED, AND FOR PREVENTING THE ENTRANCE OF HEAT
INTO APPARATUS USED FOR REFRIGERATING OR SIMILAR PURPOSES," to be as
follows:-
-
fax the

page_text: economical production and utilization of heat, and for applying heat and
abstracting it from fluids used for heating and cooling, and for pre-
venting access of heat to fluids for refrigerating, cooling, or condensing,
and to apparatus for such purposes.
It is well known that a great portion of the heat which should be
produced or generated by the proper combustion of a given quantity of
coal or other fuel in steam boiler and other furnaces in manufacturing
processes and apparatus for burning, heating, cooling, or similar purposes,
and in all cases where fuel is burned for obtaining its equivalent in
motive power or otherwise is now wasted by imperfect combustion of
the fuel, and that there is in all such furnaces, apparatus, and processes
great loss or waste of the heat that is generated or produced by reason
of the imperfect construction and arrangements existing in all furnaces,
boilers, and other apparatus wherein heat is generated or utilized.
By my Invention I utilize a large portion of the heat now wasted in
manufacturing and other operations or processes in which coal or other
fuel is used; and the said Invention is applicable to all processes,
apparatus, or machinery wherein it is necessary or desirable to use heat
economically.
According to the said Invention I heat atmospheric air by drawing or
forcing it by means of fans, exhausters, blowing cylinders, air pumps,
bellows, or any other suitable apparatus through spiral passages and
other spaces or chambers enclosed in, encasing, or surrounding the
apparatus to which the said Invention is applied, such as the metallic
or other heated surfaces of chimneys, flues, blast pipes, evaporators,
boilers, receivers, steam and gas condensers, heaters, superheaters, pipes,
tubes, mains, conducts, and other similar apparatus.
I make use of cold atmospheric air for condensing, cooling, and
refrigerating purposes, and I apply the heat absorbed by the air so used
for the purposes of heating water and other fluids for boilers and the
like superheating steam evaporating, warming, burning, calcining,
drying, and raising the temperature of air and gases in the furnaces of
steam and other boilers, evaporating pans, furnaces, cupolas, kilns,
ovens, stoves, retorts, and other fire-places and apparatus.
I obtain a double result in most instances with the same quantity of
atmospheric air by applying it, first, to purposes in the effecting of which

page_text: it absorbs heat; and, secondly, to processes in which the heat is abstracted
from it and utilized.
In all cases an important feature of my Invention is the arrangement
of the parts of the apparatus to which my Invention is applied, so that
there is a continuous circulation of the steam, water, gas, or other fluid
to be cooled or heated, preferably in a direction opposite to that of the
movement of the atmospheric air for cooling or heating the same.
Another important feature of the said Invention is that I can without
inconvenience make the cooling and heating surfaces of sufficient extent
and length to condense steam or gas produced or used in any apparatus,
and to permit the atmospheric air to absorb nearly the whole of the heat
contained in them.
I prevent the loss of heat by conduction or radiation from any vessel
or apparatus containing water, steam, gas, or other fluid by surrounding
or encasing the outer metallic or other surfaces and spiral spaces or
chambers applied to the exterior of the said apparatus with closed
metallic casings formed with cavities or spaces.
This part of my Invention may be advantageously applied to
chimneys, flues, steam and hot-air cylinders, steam and other boilers,
evaporators, salt pans, receivers, tanks, steam and gas condensers,
heaters, superheaters, furnaces, cupolas, coke and other burning or
calcining ovens, kilns, stoves, retorts, and beds of retorts, and other
similar apparatus and pipes, tubes, mains, conducts, and apparatus for
conducting or containing water, steam, gas, or other fluids. By pre-
ference I have two or more of theso cavities, one outside of or enclosing
the other, so that there will be little or no loss of heat by conduction or
radiation from within the apparatus or vessel so protected into the inner
cavity, the outer cavity or cavities preventing the access of the cooler
external atmospheric air to reduce the temperature in the said inner
cavity, and in like manner in apparatus for producing cold I prevent the
penetration of heat from without.
This part of my Invention is advantageously applicable to the
covering of open evaporating pans and similar vessels for preventing
the loss of heat therefrom and retaining it to be utilized for any desired
purpose.
I use joints for these cavity casings and the apparatus to which
they are applied that can be easily connected and disconnected, and I

page_text: other fluids, superheating steam, or for similar purposes. It may be
also used for raising the temperature of furnaces, and will greatly increase
and economize the heat produced therein.
My Invention will also effect great economy in apparatus for conden-
sation, cooling, and refrigerating by preventing the penetration of heat
to the cold atmospheric air used for these purposes.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said Edwin Maw in the Great Seal Patent Office on
the 24th April 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWIN
Maw, of Liverpool, in the County of Lancaster, Civil Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fifth day of October, in the
year of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and successors
give and grant unto me, the said Edwin Maw, Her special licence
that I, the said Edwin Maw, my executors, administrators, and
assigns, or such others as I, the said Edwin Maw, my executors,
administrators, and assigns, should at any time agree with and no others
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS RELATING
TO THE APPLICATION OF ATMOSPHERIC AIR FOR PREVENTING THE WASTE OR LOSS OF
HEAT IN PROCESSES AND APPARATUS WHEREIN HEAT IS GENERATED OR UTILIZED,
AND FOR PREVENTING THE ENTRANCE OF HEAT INTO APPARATUS USED FOR
REFRIGERATING OR SIMILAR PURPOSES," upon the condition (amongst others)
that I, the said Edwin Maw, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said Inven-
tion, and in what manner the same was to be performed, and cause the
same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters
Patent.

page_text: NOW KNOW YE, that I, the said Edwin Maw, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement, reference being had to the accompanying Drawings
forming a part of this Specification :-
My Invention relates to the application of atmospheric air for the
economical production and utilization of heat for supplying heat to and
abstracting it from fluids used for heating and cooling purposes, and
for preventing the access of heat to fluids for refrigerating, cooling, or
condensing purposes, and to apparatus for effecting these objects.
It is well known that a great portion of the heat which should be
produced or generated by the proper combustion of a given quantity of
coal or other fuel in steam boiler and other furnaces in manufacturing
processes, and apparatus for burning, heating, cooling, or similar
purposes, and in all cases where fuel is burned for obtaining its equi-
valent in motive power or otherwise, is now wasted by imperfect
combustion of the fuel, and that there is in all such furnaces, apparatus,
and processes great loss or waste of the heat that is generated or
produced by reason of the imperfect construction and arrangements
existing in all furnaces, boilers, and other apparatus wherein heat is
generated or utilized.
By my Invention I utilize a large portion of the heat now wasted in
manufacturing and other operations or processes, in which coal or other
fuel is used. And the said Invention is applicable to all processes,
operations, apparatus, or machinery wherein it is necessary or desirable
to use heat economically.
According to the said Invention I heat atmospheric air by drawing or
forcing it by means of fans, exhausters, blowing cylinders, air pumps,
bellows, or any other suitable apparatus through spiral passages and
other spaces or chambers enclosed in, encasing, or surrounding the
apparatus to which the said Invention is applied, such as the metallic or
other heated surfaces of chimneys, flues, blast pipes, evaporators, boilers,
receivers, steam and gas condensers, heaters, superheaters, pipes, tubes,
conduits, and other similar apparatus.
I make use of cold atmospheric air for condensing, cooling, and
refrigerating purposes, and I apply the heat absorbed by the air so used
for the purposes of heating water and other fluids for boilers, and the

page_text: like superheating steam evaporating, warming, burning, calcining,
drying, and raising the temperature of air and gases in the furnaces of
steam and other boilers, evaporating pans, furnaces, cupolas, kilns,
ovens, stoves, retorts, and other fire-places and apparatus.
I obtain a double result in most instances with the same quantity of
atmospheric air, by applying it first to purposes in effecting which it
absorbs heat, and, secondly, to processes in which the heat is abstracted
from the air and utilized.
In all cases an important feature of my Invention is the arrangement
of the parts of the apparatus to which the said Invention is applied, so
that there is a continuous circulation of the steam, water, gas, or other
fluid to be cooled or heated preferably in a direction opposite to that of
the movement of the atmospheric air for cooling or heating the same.
Another important feature of the said Invention is the peculiar
construction whereby I can without inconvenience make the cooling and
heating surfaces of sufficient extent to condense steam or gas produced
or used in any apparatus, and to permit the atmospheric air to absorb
nearly the whole of the heat contained in them, while all portions of the
passages and other parts of the apparatus employed are made in such a
manner, that though the metal is of very slight thickness the structure
will be of great strength, so that there is no danger of the bursting or
collapsing of any part of the same.
I prevent the loss of heat by conduction or radiation from any vessel
or apparatus containing water, steam, gas, or other fluid, by surrounding
or incasing the outer metallic or other surfaces, and the spiral spaces or
chambers applied to the exterior of the said apparatus with closed
metallic casings formed with cavities or spaces, and which I term cavity
casings.
This part of my Invention may be advantageously applied to
chimneys, flues, steam and hot-air cylinders, steam and other boilers,
evaporators, salt pans, receivers, tanks, steam and gas condensers,
heaters, superheaters, furnaces, cupolas, coke and other burning or
calcining ovens, kilns, stoves, retorts, and beds of retorts, and other
similar apparatus, and mains, or other pipes or tubes, conduits, and
apparatus for conducting or containing water, steam, gas, or other fluids.
By preference I have two or more of these cavities one outside of or

page_text: enclosing the other, so that there will be little or no loss of heat by
conduction or radiation from within the apparatus or vessel so protected
into the inner cavity, the outer cavity or cavities preventing the access
of the cooler external atmospheric air to reduce the temperature in the
said inner cavity; and in like manner in apparatus for producing cold,
I prevent the penetration of heat into the said apparatus from any source
external to the same.
This part of my Invention is advantageously applicable to the
covering of open evaporating pans and similar vessels for preventing
the loss of heat therefrom and retaining it to be utilized for any desired
purpose.
I use joints for these cavity casings and the apparatus to which they
are applied, that can be easily connected and disconnected, and I provide
them with distributors, guides, branches, and connections to facilitate
the continuous and uninterrupted circulation of air, steam, gas, water,
or other fluid, and I provide for expansion and contraction of the
said casings by expansion joints, springs, friction,rollers, and similar
devices.
Another feature of my Invention, which is very important, is the
manner of its application to large pans, boilers, tanks, or receivers that
have to be partially uncovered during their working by the opening of
doors, lids, or covers. I prevent the escape of steam, vapour, or heat
from the other parts of these vessels while they are thus open or un-
covered by providing them with vertical ribs or partitions dipping into
the liquid contained in them, as herein-after more fully described.
Another part of my said Invention relates to the novel construction
of apparatus, as herein-after described, for heating or cooling water and
other liquids, condensing or heating vapours or gases, and for analagous
purposes, and this apparatus may be adapted to serve either as a con-
denser, refrigerator, or superheater. Various forms, modifications, and
applications of this part of my Invention are shown in the accompanying
Drawings.
Another application of my Invention is for the production of a
vacuum or partial vacuum in steam cylinders and evaporators by the
action of cold air surrounding and circulating through condensers con-
nected with them, and I utilize the heat absorbed by the atmospheric

page_text: air for heating water and other fluids, superheating steam, or for similar
purposes, instead of allowing it to be lost or wasted, as heretofore. It
may be also used for raising the temperature of furnaces, and will greatly
increase and economize the heat produced therein.
My Invention will also effect great economy in apparatus for con-
densing, cooling, and refrigerating, by preventing the penetration of heat
to the cold atmospheric air used for these purposes.
In the accompanying Drawings I have illustrated the application of
my Invention to apparatus constructed for some of the various purposes
above enumerated and analagous-purposes, and I will now proceed by
the aid of these Drawings to more fully and clearly explain the manner
in which the said Invention may be advantageously carried into practice
in connection with any apparatus in which heat is generated, utilized,
or stored, or into which it is desired to prevent its entrance. The form,
construction, and arrangement of the spiral passages, chambers, or
spaces, whereby I provide for a continuous circulation of the fluids, with
only a very thin substance of metal between them, while ensuring the
required strength to the various parts of the passages and casings and
their connections, and prevent the loss or waste of heat by radiation or
conduction, are clearly illustrated in the Drawings; but it will be
readily understood that these Drawings do not include all of the appli-
cations of which my Invention is capable, and that the precise
arrangement of these spiral passages, and other applications of my
Invention, in any particular case will vary according to the construction
of the apparatus, machine, utensil, vessel, or structure to which they are
applied, and to the nature of the work or operation to be performed
therehv

page_text: Figure 5 is an end view of smaller apparatus for the same purpose;
Figure 6 is a longitudinal section of Figure 5.
Figure 7 is a side view of vertical apparatus with part of my In-
vention applied, which will serve either as a condenser, refrigerator, or
warm water (of condensation) heater.
Figure 8 is an end view of an apparatus for carrying my Invention
into practice as a superheater, water heater, evaporator, condenser, or
refrigerator; Figure 9 is a longitudinal section of Figure 8.
Figure 10 is a side elevation of a flue and chimney for a steam boiler
or other furnace or fire-place, with my Invention applied to the same;
Figure 11 is a top view of Figure 10.
Figure 12 is a plan of a locomotive or portable engine boiler, shewing
the application of my Invention to the chimney, horizontal superheater,
horizontal hot water heater, vertical condensers, and warm water (of
condensation) heater.
Figure 13 is a horizontal section of the ascending pipe of a gas
retort.
Figure 14 is a transverse section of a hydraulic main; Figure 15 is a
horizontal section of a gas condenser; and Figure 16 is a plan of a gas
holder and tank, illustrating the application of my Invention to such
apparatus; Figure 17 is a vertical section of Figuro 16.
Figure 18 is a section of a pipe for steam, water, air, gas, or any other
fluid.
Figure 19 is an end view of apparatus comprising horizontal cylin-
drical superheaters, water heaters, and evaporators, condensers or refri-
gerators, with their receivers underneath, and vertical condensers or
refrigerators supported on suitable framing, illustrating the application
of my method of economising heat by the circulation of fluids in con-
tinuous passages, and by the employment of cavity or hollow casings on
the radiating or conducting surfaces.
Figure 20 is an end view of six horizontal flat or oval vessels to be
used as evaporators, condensers, refrigerators, or warm water (of con-
densation) heaters with receivers underneath, and two vertical condensers,
refrigerators, or warm water (of condensation) heaters, or receivers
mounted on suitable framing, also illustrating the application of my said

page_text: Invention Figure 21 is a plan of Figure 20; Figure 22 is a side
elevation of Figure 20.
Figure 23 is a transverse section of part of one of the said oval
evaporating pans, shewing a clip and cotter applied to the flanges of said
pan and its cover, or used for analogous purposes, and the mode of con-
necting two of such pans, whereby I ensure the tight connection
between all parts of such apparatus necessary for the purpose of my said
Invention Figure 24 is an end view of the clip and cotter shewn in
Figure 23; Figure 25 is a plan of the same.
Figure 26 illustrates the method of attaching india-rubber or other
packing to the flanges of the evaporating pans, or the like or analagous
purposes to form tight joints for the same which may be varied to suit
the appliances they are used for; Figure 27 is a side view of Figure 26.
Figure 28 is a side view illustrating the construction of a circular
cavity casing with distance piece between cylinder, forming spiral
space.
Figure 29 is a section of one of these distance pieces in the cavity
casing.
Figure 30 is a section of joint or distance picces for air and steam
spaces, and also for the cavity casing of evaporating pans and the like.
Figure 31 is a side view of a modification of these joint or distance
pieces.
Figure 32 is a plan of joint distance pieces with screw bolts, nuts,
and washers for cavity casings; Figure 33 is a plan illustrating the
mode of connecting the same.
Figures 34, 35, and 36, shew the said washers and bolt or screw
detached.
Figure 37 is a section of the end joint of one of the aforesaid spiral
cylinders.
Figure 38 which illustrates the application of my Invention for the
production of a vacuum or partial vacuum, is a plan partly in section of
apparatus consisting of four circular evaporating pans provided with
passages of a volute form, and with cavity casings and central dis-
tributors and connections, whereby I ensure the continuous circulation
of the fluids throughout their entire length of the surfaces of said
apparatus, and prevent the loss of heat by radiation or conduction

page_text: Figure 40 is a side elevation of salt pans with my Invention applied
to the same as herein-after described; Figure 41 is a plan partly in
section of Figure 40; Figure 42 is an end view of the same.
Figure 43 is a side elevation illustrating the application of my Inven-
tion in a similar manner to sugar or chemical pans; Figure 44 is a
plan; and Figure 45 an end view of the same.
In Figures 1 and 2 I have shewn an apparatus of entirely novel con-
struction, which is based upon the employment of the aforesaid spiral
passages, and which construction may be adapted to either a condenser
or refrigerator, heater or superheater, but which is here shewn as a con-
denser. The body a of this apparatus is composed entirely of concentric
series of cylinders, and spiral passages, chambers or spaces separated
from each other by thin metal. The ends of the said apparatus are
provided with distributors c, c', and their guides are connected by their
branches and apertures c³, c', with the spiral air passages or chambers a¹,
and the distributors d, d', are connected by similar branches and aper-
tures d', d', with the steam passages or spaces a². The steam and air
passages are arranged alternately, that is to say, each steam passage is
between two air passages. The thin metal cylinders f' whereby the air
and steam passages are separated from each other have their spiral
spaces or passages also separated from each other by thin sheet metal,
and of a size and inclination or pitch varied in proportion to the
diameters of the different circles of these spaces. The said apparatus
is also provided with a receiver a* which collects the water of condensa-
tion from the spiral steam passages in which suitable openings are left,
and outlets provided for the flow of the water of condensation. The
distributor c receives the air through the inlet c from a fan or other
blowing or draught producing apparatus, and distributes the same
through the said branches to the said spiral passages a' through which it
passes in the direction indicated by the arrows 1 in its passage from one
end to the other of the apparatus, passing many times around the same.
The steam is at the same time entering at the aperture d' of the dis-
tributor d, and passing through the branches d³ and spiral passages a³ in
a direction opposite to that of the air as indicated by other arrows. I use

page_text: expansion joints where the same are necessary or desirable for any of
the connections of my apparatus.
One important advantage arising from the peculiar construction
above described, is that in an apparatus which is very compact, that is
to say, which is not of inconvenient length or diameter I have a very
large area of surface over which the steam is exposed to the cooling or
heating action of the air, and I therefore obtain a result which with any
other known method of construction could only be obtained with an
apparatus whose great length would render its employment extremely
inconvenient, and in most cases totally impracticable, and I wish it
clearly understood that in the application of atmospheric air for the
various purposes above cnumerated or any of them or other like
purposes, any advantages I obtain are due to this principle of the above
described peculiar construction and arrangement of the passages by
which within the dimensions of ordinary apparatus for any of such
purposes the fluids or gases are exposed to each other's action over such
an area of heating or cooling surface as will permit the whole or nearly
the whole of the heat to pass from one to the other of the said fluids or
gases, as may be desired. But in combination with this peculiar con-
struction of spiral passages I employ the aforesaid cavity casings which
form another very important feature of my Invention.
These cavity casings or hollow or chambered coverings which I employ
in various forms for the prevention of the loss of heat by radiation or
conduction from any vessel, utensil, structure, or apparatus, or the
penetration of heat into any vessel, utensil, structure, or apparatus, are
shewn in various Figures of the Drawing.
The apparatus shewn in Figures 1 and 2 is provided on the outside
with these peculiar casings, as shewn at g. I have shewn this casing as
composed of one inner and one outer cavity or chamber, but although I
never use or construct them with less than two cavities, chambers, or
spaces, one enclosing or surrounding the other, yet I may construct
them with three or more of such cavities, spaces, or chambers, if I find
it necessary or convenient to do so. Figures 32 to 36 illustrate a
convenient manner of securing these casings upon a cylindrical or other
utensil, vessel, structure, or apparatus, such as that shewn in Figure 1,
or a steam boiler or the like; h is the outer shell of the said boiler or
other vessel; ' is the first cavity or space which is enclosed within the

page_text: thin metal casing or shell g³; 9' is the second or outer cavity or space
enclosed between the shell g³ and the outer thin metal shell g³. It will
be understood that these casings may be applied to the entire surface of
the boiler, cylinder, or other vessel, utensil, structure, or apparatus to be
protected, or to such portion or portions thereof as require protection.
The thin metal shells or casings g², 9, are supported by and attached to
hollow rings or annular chambers g', g', of which any required number
may be used.
It will be observed that in these rings or annular chambers the
principle of construction involving the inner and outer cavities or
chambers is adhered to, so that these rings are as effective as any other
part of the casing for the purpose above specified. These rings are
provided with junction pieces g³, 9, to secure them to the thin metal
casings. The said junction pieces are formed of thin metal bent or
folded in the proper shape. The inner ring is secured to the shell of
the round or flat surface of any boiler or other vessel or apparatus by
screws 10, which are accessible through holes of the peculiar shape
shown at g".
It will be seen by referring to Figures 33 and 34 that the said holes
arc of such a form as to permit a screw head to pass through one
portion of them, but not through the other portion. Therefore to
secure the outer cavity or chamber upon the inner one I pass the screw
head 2 having the smaller washer 5 under it through the large part of
the hole in it through the washer 3 with a hole of the same shape, and
placed over it in the position shewn in Figure 33, and then slido the
head under the small part thereof. Then after turning washer 3 a
quarter round, as shewn in Figure 34, so as to cover the said hole, I
tighten the nut 1. I provide a similar hole on the outside of the outer
cavity or chamber to allow access to the said nut and washer, and this
outer hole is also covered with a plate or washer secured by a screw nut
or otherwise, and completely closed by turning the washer 3 round as
above described.
In Figures 1 and 2 I have illustrated another feature of my improve-
ments which I adopt in the construction of large apparatus or vessels.
The inner portion of this apparatus is made separate from the outer
portion, and is so fitted therein that it may be readily removed or
replaced when necessary for repairing or other purposes. It is obviously

page_text: not practicable to fit these two portions so accurately as to leave no
space between them. I therefore form the one to enter freely into the
other and provide the exterior periphery of the first or inner portion and
the adjacent interior periphery of the second or annular portion sur-
rounding the same with a cavity chamber, these two cavities, with the
space between them, forming an additional cavity around the two
portions of the apparatus in addition to the cavities encasing or
surrounding the outer sides and ends of the apparatus, and I may
also construct the said apparatus with a third portion surrounding the
said second portions, or with any greater number of portions or parts
surrounding each other, with similar spaces or cavities at ; between the
two portions, as above described.
The construction of the apparatus shewn in Figure 3 is substantially
similar to that shewn in Figures 1 and 2, except that it is of smaller
diameter, and has a smaller number of spiral passages or chambers a¹, a²,
for the currents of air and steam or other fluids. The small number
of these passages permits the use of distributors of simpler form, as
shewn. The air and steam or other fluids whose heat is to be taken
from one to the other enter the distributors and pass through them to the
spiral passages a¹, a², and are conducted away from the same in opposite
directions, as above described.
In Figures 4, 5, and 6 I have shewn an apparatus of similar con-
struction, but with a blast pipe or tube passing through its centre
with or without spiral passages. This apparatus may be used at the same
time for heating the air of the blast, condensing the exhaust steam of the
engine, and improving the combustion of furnaces, cupolas, or other
vessels, or for other like purposes. In addition to the air passing through
the blast pipe or tube steam and air enter the distributors c, d, at
opposite ends of the apparatus, and pass through the same and the
spiral passages a, a, in opposite directions, as above described. The
steam heats the blast, and is in turn cooled and condensed by the
action of the air while the latter is being heated before it escapes from
the apparatus, and is conducted to the furnaces, cupolas, or other
vessels, or utilized for any other purpose, while the water of conden-
sation in a heated state flows or is pumped up or drawn into a tank or
other vessel to be supplied to the boilers or to be used elsewhere as
required.

page_text: A very important application of my said Invention is for saving
the heat, which is ordinarily allowed to escape into the atmosphere
from locomotive, marine, and stationary engines, and other chimneys
and flues. This application of the said Invention is illustrated in
Figures 10 and 11, and may be modified when necessary. The chimney
is surrounded by spiral passages at m connected with an inlet aper-
ture m' and outlet aperture m³. A current of cold atmospheric air is
forced or drawn downward by a fan or other suitable means through
these apertures and passages, passing many times around the chimney
and flue, and absorbing the greater portion of the heat ascending with
the vapour and smoke through the same. The heated air as it issues
from the spiral passages at the bottom of the chimney is conducted to a
superheater, condenser, or feed water heater, or to a furnace, fire-place,
or other apparatus to improve combustion, or is distributed into any or
all of these parts, or used for any other purpose.
Figure 12 shews a portable engine provided with two vertical con-
densers n, n, a horizontal superheater n', and horizontal feed water
heater 1, and with a chimney provided with my improved heat-saving
device.
Figure 19 is an end elevation of apparatus which may be used for
either evaporating, refrigerating, superheating, or similar purposes.
A is a framework of iron or other suitable material; p, p, are vertical
condensers, tubes, or cylinders; and p', p³, p³, p', p³, pº, are horizontal
tubes or cylinders provided with my cavity casings and with spiral
passages constructed and arranged as above described. The cold or hot
air is admitted into the said apparatus at one end of one of these
cylinders and forced or drawn through the same in one direction, while
the fluid to be cooled or heated passes through the said apparatus in the
opposite direction. The horizontal tubes or cylinders and vertical con-
densers or vessels are provided at the bottom with receivers p' for a
collecting the condensed liquid, the said receivers being surrounded with
double hollow chambers or cavity casings, as above described.
In Figures 20, 21, 22, I have shewn an apparatus consisting of an
arrangement of evaporating pans, condensers, or refrigerators in com-
bination with vertical condensers.
The framework A is similar to that shewn in Figure 19, and the
vertical condensers q, q, are similar in construction to those shewn
8

page_text: therein q', q, q, q', 9, 9º, are long flat pans surrounded with passages
for currents of air or steam, and with my cavity casings or doublo
hollow chambers for preventing the loss of heat by radiation or con-
duction therefrom. Communication between these pans is effected
through the pipes or tubes q', which are arranged at the ends of tho
said pans, so that they do not interfere with the fitting on or removal of
the covers q. The contents of these pans pass from one to the other
through inlet apertures at q³ and ontlet apertures at qº.
Figures 23, 24, 25, 26, and 27 illustrate devices for securing the said
covers tightly in their place on the said pans, or other utensils, struc-
tures, vessels, or apparatus. The said pans and covers have projecting
rims or flanges as shewn extending all round them, and between these
rims or flanges I enterpose a packing 5 of india-rubber or other suitable
material, as most clearly shewn in Figure 23. This india-rubber or
other packing is attached to the lids or covers q* by small flanged metal
cups 6, which are fitted into recesses formed in the said packing, as
shewn in Figures 26 and 27, and secured to the cover by screw bolts or
other fastenings. The said covers when in place on the pans are secured
by the clips 7, which are tightened, and cause the aforesaid flanges of
the pan and cover to form a close joint with the india-rubber or other
packing by means of keys or cotters 8 driven in between the said clip
and the flange, as shewn in Figures 23, 24, and 25.
In Figures 8 and 39 I have illustrated the adaptation of my
Invention to a set of four evaporating pans to be used with or without
a vacuum or partial vacuum, and constructed with passages of a volute
spiral form, whereby the steam and air or other fluids used for heating
and cooling travel many times around the said pans in passing from the
centre to the perimeter, or vice versa, exerting their heating and cooling
effects upon the fluid to be evaporated or steam to be condensed
throughout the entire extent of the volute or spiral surfaces. In this
apparatus 7, 8, are two central distributors; 11, 72, 73, 7, are the four
evaporating pans connected to the said distributors by pipes ³, &¹; tis
a central receiver connected to the said pans by pipes ', . The pans
are constructed with covers *, which are fitted with tight joints upon
pans as above described. The lower part of the pipes is attached
to the covers, and made to slide telescopically in the upper part of the
said pipe to allow the said covers to be raised and lowered when required.
Chains and weights are provided for balancing and supporting the said
B

page_text: '
covers. The body or central portion of these pans is filled with the
liquid to be heated or evaporated. The hot air or steam for evaporating
this liquid is admitted into the distributor 8, and thence conducted by
the pipes to the inner volute steam passage, and passes therefrom
through the various coils and the pipes to one compartment of the
receiver; at the same time cold air supplied to the distributor » passes
through the pipes,,, to the inner volute air passage, and thence
around the intermediate coils to the outside of the pan, and through the
pipe to the other compartment of the receiver. The air being heated
and the steam or hot air cooled in passing through the apparatus both
will enter the distributor at, or nearly at, the same temperature,
and may be supplied from the said receiver to any apparatus to be
utilized.
The condensers shewn in Figures 3 and 7 may be used in common
with these pans.
The volute air passages a' and steam passages &² are arranged as
shewn, and as the metal forming these passages is very thin the heat
will pass rapidly from one fluid to the other while the air and steam are
travelling through the said passages.
The aforesaid distributors, pipes, pans, and receivers are provided with
my hollow or cavity casings on all portions of their radiating or con-
ducting surfaces.
In Figures 40, 41, and 42, I have shown a very advantageous
application to salt pans of my Invention for economizing heat. Ordinary
salt pans are so constructed that in using them every time it is necessary
to remove the lids the greater portion of the heat escapes and is wasted.
I prevent this waste of heat by providing the pans u with vertical
longitudinal, and transverse partitions, shewn in dotted lines, which
dip into the liquid in the pans and separate the same into compartments
of sufficient size to allow the salt to be removed, so that when any one
of the covers u¹ is raised only a small portion of the contents of the pan
is in communication with the opening thereby exposed. I economize
the whole, or nearly the whole, of the heat of the steam produced in
these pans by connecting with them an arrangement of pipes as shewn;
all the compartments or divisions of the pan are connected. by vertical
pipes to with two main pipes to. The steam ascends through the said
vertical pipes into the mains wo, and is thereby conducted to the

page_text: evaporating pans or other apparatus before described, or to any other
receptacle or apparatus where the heat is to be stored or utilized. These
pans and pipes are provided with my hollow or cavity casings, as clearly
shown in the Drawings. The covers a² are suspended on chains provided
with counterbalance weights, whereby their raising and lowering is
rendered easy and convenient. The flue and chimney are provided with
the cavity casings and spiral air passages for economizing the heat, as
described with reference to Figures 10 and 11; and when desirable a
vacuum or partial vacuum may be produced in these paus by means of
the condenser shewn in Figures 3 or 7.
Figures 43, 44, 45, shew a similar application of my Invention to
sugar or chemical pans.
Having thus fully described my said Invention, and shewn how the
same may be conveniently and advantageously carried into practice, I
wish it understood that I claim,-
First. The application of atmospheric air for heating or cooling
purposes by drawing or forcing it through spiral passages whose surfaces
arc in contact with the fluid to be heated or cooled, and which are
so formed and arranged that the action of the hot or cold air upon the
fluid to be heated or cooled will be sufficient to effect the heating or
cooling of the same to the desired degree before it leaves the said spiral
passages.
Second. Preventing the escape of heat by radiation or conduction
from any vessel, utensil, apparatus, or structure in which heat is
generated, stored, or utilized; or the entrance of heat into any vessel,
utensil, apparatus, or structure in which it is desired to maintain a
refrigerating, cooling, or condensing action, by the employment of
closed casings with two or more cavities or spaces, one within the other,
on the exterior or radiating or conducting surfaces of the said vessel,
utensil, apparatus, or structure, as herein set forth.
Third. The application of my Invention to the apparatus shewn in
Figures 1 and 2, consisting of a series of concentric cylinders with spiral
passages connected at their ends with distributors which have inlet and
outlet apertures, and are supplied with air and steam or other fluids,
as herein set forth and for the purposes specified.
Fourth. The combination of parts comprising my internal spiral
conducting passages and external cavity casings arranged upon or in

page_text: connection with a locomotive, portable, traction, marine, stationary, or
other engine or boiler furnace or fire-place, for economising the heat
passing up the chimney, and utilizing the same for superheating,
warming, condensing, and other purposes, as herein set forth.
Fifth. The peculiar construction of the joints for the said cavity
casings and other parts of my improved apparatus for economizing or
utilizing heat or cold, or for similar purposes, as herein set forth.
Sixth. An evaporating pan or similar vessel for boiling or heating |
liquids constructed with double chambers or cavity casings, and provided
with has vertical ribs or partitions which dip into the liquid in the said
pan or vessel, as herein set forth and for the purposes specified.
Seventh. An evaporating pan constructed with passages or spaces for
the circulation of air or steam around the same, and with the aforesaid
cavity casings or double chambers, and with devices for securing the
lids or covers tightly and securely upon the same, as herein set forth.
Eighth. Securing the cavity casings or chambers upon the vessels,
utensils, structures, or apparatus to which they are applied by means of
joints, hollow rings, or annular chambers, and fastening devices, as
illustrated in Figures 32 to 36, and as herein specified.
Ninth. The construction of the spirally chambered condenser, illus-
trated in Figures 1 and 2, in two or more concentric parts, consisting
of spiral passages and fitted together with cavities or chambers sur-
rounding the adjacent surfaces of the said concentric parts, as herein
set forth and for the purposes specified.
0
In witness whereof, I, the said Edwin Maw, have hereunto set my a
hand and seal, this Twenty-second day of April, in the year of
our Lord One thousand eight hundred and seventy-six
Witness,
EDWIN LISTER MAW.
EDWIN MAW. (L.S.)