Improvements in Apparatus for Heating Air.
Year: 1888

page_text: Date of Application, 8th Sept., 1888
Complete Specification Left, 8th June, 1889-Accepted, 31st Aug., 1889
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Heating Air.
We, PETER LITTLER of 22 Hackins Hey, Cotton Merchant, THOMAS HASLAM of
77 Regent Road, Engineer, and, JOHN MOORCROFT of 77 Regent Road Engineer, all
of Liverpool in the county of Lancaster, do hereby declare the nature of this
invention to be as follows:-
According to our present invention we construct apparatus for heating air as
follows :- -We provide a metallic vessel having an inner chamber, which vessel will
hereinafter be termed the air heater, preferably of that shape which is obtained when
two concentric cylinders are cut by a plane which is parallel to their axis; herein-
after that part of the vessel formed by the cutting plane will be called the base of
the vessel. Two stacks of tubes are placed within the inner chamber, the tubes
being parallel to the axis thereof, and the ends of the tubes passing through the ends
of the said chamber, which will hereinafter be called the tube plates, so as to make
steam-tight connections therewith.
At each end of the air heater the base, and the shell of the outer vessel, are
prolonged some distance beyond the tube plates, and covers or doors are attached
thereto, so forming a pocket at each end of the vessel. One of these pockets is
divided into two compartments by a vertical diaphragm extending from the tube
plate to the cover or door.
At one side an air inlet is formed by an opening in the base of the annular space
between the outer vessel and the inner chamber, and the said space communicates at
the opposite side with one of the compartments of the pocket hereinbefore described,
and an opening is made in the base of the other compartment of the pocket, which
will hereinafter be termed the outlet.
The form of the air heater is such that it may be readily combined or incorporated
with a vertical boiler of the ordinary type, an opening of sufficient diameter being
made in the base of the inner chamber which is attached to the boiler a little above
the crown of the firebox, the inner chamber thus forming the steam chamber of the
boiler, and the stacks of tubes being so disposed as to permit of the flue of the boiler
passing between them and up through the top of the air heater.
We either force or draw a current of the air to be heated through the annular
space, and the tubes in the following manner :-The current of air enters the inlet
in the base and passes through the annular space, then through the opening in the
end of the annular space into one of the compartments of the double pocket, it then
passes through that stack of tubes whose ends open into this compartment into the
single pocket, then back through the remaining stack of tubes into the remaining
compartment of the double pocket, and so to the outlet by which the current of air
leaves the air heater.
The temperature of the air is raised during its passage through the air heater by
the heat which has been transferred to it from the steam, first through the shell of
the inner chamber, and second through the tubes.
Any other form of boiler may bo substituted for the vertical boiler; in the case of
a horizontal boiler the air heater may be placed as a steam chamber or dome on the
top thereof; or the air heater may be detached from the boiler, and suitable pipe
connections provided.
We do not limit ourselves to the particular form of air heater described, which may
be modified in various ways, the essential feature being the passage of the current
1

page_text: of air round the shell of the inner chamber before it passes through the tubes, and
the passage of the air through two or more stacks of tubes so as to traverse the length
of the air heater two or more times.
Dated this 7th day of September 1888.
SLOAN & LLOYD BARNES,
26, Castle Street, Liverpool, Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Apparatus for Heating Air.
We, PETER LITTLER of 22 Hackins Hey, Cotton Merchant, THOMAS HASLAM of
77 Regent Road, Engineer and JOHN MOORCROFT of 77 Regent Road, Engineer, all
of Liverpool in the county of Lancaster, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
:-
According to our present invention we construct apparatus for heating air as
follows: We provide a metallic vessel having an inner chamber, which vessel will
herein-after be termed the air heater, preferably of that shape which is obtained when
two concentric cylinders are cut by a plane which is parallel to their axis; herein-
after that part of the vessel formed by the cutting plane will be called the base of
the vessel.
Two stacks of the tubes are placed within the inner chamber, the tubes being
parallel to the axis thereof and the ends of the tubes passing through the ends of the
said chamber which will hereinafter be called the tube plates, so as to make steam-
tight connections therewith.
At each end of the air heater, the base and the shell of the outer vessel are prolonged
some distance beyond the tube plates, and covers or doors are attached thereto, so
forming a pocket at each end of the vessel.
One of these pockets is divided into two compartments by a vertical diaphragm
extending from the tube plate to the cover or door.
At one side an air inlet is formed by an opening in the base of the annular space
between the outer vessel and the inner chamber and the said space communicates at
the opposite side with one of the compartments of the double pocket hereinbefore
described, and an opening is made in the base of the other compartment of the
double pocket, which will hereinafter be termed the outlet.
The form of the air heater is such that it may be readily combined or incorporated
with a vertical boiler of the ordinary type, an opening or openings of sufficient
diameter being made in the base of the inner chamber, which is attached to the boiler
a little above the crown of the firebox, the inner chamber thus forming the steam
chamber of the boiler, and the stacks of tubes being so disposed as to permit of the
chimney or uptake of the boiler passing between them and up through the top of
the air heater.
•
We either force or draw a current of the air to be heated through the annular.
space and the tubes in the following manner :-
The current of air enters the inlet in the base and passes through the annular space,
then through the opening in the end of the annular space into one of the compart-.
ments of the double pocket, it then passes through that stack of tubes whose ends
open into this compartment, into the single pocket, then back through the remaining
stack of tubes into the remaining compartment of the double pocket, and so to the
outlet by which the current of air leaves the air heater.
The temperature of the air is raised during its passage through the air heater by
the heat which has been transferred to it from the steam, first through the shell of the
inner chamber, and second through the tubes, and by gradually heating the air, as

page_text: described, before it reaches the tubes, the prejudicial effects of a current of cool air
on the connections between the tubes and tube plates are avoided. If it be desired
to raise the air to a still higher temperature before reaching the tubes it may be led
to the air heater through an annular passage surrounding the chimney or uptake of
the boiler.
Where the steam is of high pressure, the use of flat surfaces exposed to steam
pressure is objectionable, and in such cases, we slightly modify the construction by
completing the cylindrical shell of the inner chamber, and of the outer vessel so far
as may be necessary to form the attachment to the boiler, the flat base hereinbefore
described being thus dispensed with.
Any other suitable form of boiler may be substituted for the vertical boiler; in the
case of a horizontal boiler the air heater may be placed as a steain chamber or dome
on the top thereof, or the air heater may be detaclied from the boiler and suitable pipo
connections provided.
In order that our invention may be more readily understood, reference is made to
the accompanying drawings which form part of this specification, in which Figs. I
to X inclusive show our invention as applied to a vertical boiler, Figs. I and II
showing a form suitable where steam of moderate pressure is used, and Figs. III to X
inclusive showing a form suitable where steam of higher pressure and therefore
higher temperature is used.
Figs. XI,. XII, and XIII show diagrammatically our invention as applied to a
horizontal boiler.
Throughout the drawings similar parts are indicated by similar reference figures
and in the case of sections, the direction in which they are viewed is denoted by the
small arrows placed adjacent to the letters indicating the plane of section.
Plates and tubes in section are shown by thick lines. Referring now to the form
shown in Figs. I and II, Fig I is a sectional elevation on the line A A of Fig. II,
and Fig. II is a sectional plan on the line B B of Fig. I.
1 is the shell of the boiler, 2 is the firebox and 3 is the firedoor, the firebars and
minor details being omitted; 4 is the chimney.
5 is the cylindrical shell of the inner chamber, the ends of the chamber being
formed by the tube plates 6 and 7. This chamber communicates with the interior
of the shell 1 by the openings S in the base 23, so that the space within the chamber
forms part of the steam space of the boiler.
Two stacks of tubes 9 and 10 pass steam-tight through the tube plates: the ends
of each stack open into the pocket 12, the stack 9 connecting the pocket 12 to the
compartment 11, and the stack 10 connecting the pocket 12 to the compartment 13.
14 is the cylindrical outer shell of the air heater which is concentric with the
inner shell 5 and forms the annular space 15 between the said shells.
The outer shell 14 and the base 23 are carried beyond the shell 5, and the ends
are closed by the covers or doors 16, 17, and 18, so forming the pocket 12 and the
compartments 11 and 13.
The space 15 communicates with the compartment 11 but is separated from the
pocket 12 by the annular division plate 19, and from the compartment 13 by
the annular division plate 20. The compartments 11 and 13 are separated by the
vertical diaphragm or division plate 21.
22 is the air inlet, and the air outlet is at the bottom of the compartment 13
which is open, the base being here cut away for this purpose; the air pipe or trunk,
which is not shown, for leading the heated air to its destination is slipped into the
air outlet.
The action of the apparatus is as follows:-
The boiler being filled to the proper level with water and steam being raised till
a sufficient pressure is attained, we either force or draw a current of the air to be
heated through the air heater.
The air enters at 22 and passes through the annular space 15 into the compart-
ment 11, then through the stack of tubes 9 into the pocket 12, then through the

page_text: stack of tubes 10 into the compartment 13 and finally leaves the air heater by the air
outlet.
4
If necessary the tubes may be divided into three or more stacks and the pockets
subdivided so as to cause the current of air to traverse the length of the air heater
more than twice, after the manner well understood in surface condensers and the
like.
As many of the tubes 9 and 10 as may be thought necessary are fitted as stay-tubes
to support the tube plates.
The steam stop valve for withdrawing steam and the safety valve, (which together
with other obviously necessary fittings are not shown) are placed as high as possible
on the shell 5.
Referring now to the form of the apparatus suitable for steam of higher pressure
shown in Figs. III to X inclusive.
Fig. III is an elevation, Fig. IV is a plan, Fig: V is a sectional elevation on the
line of Fig. VI, Fig. VI is a sectional plan on the line D D of Fig. V, Figs. VII
and VIII are sectional elevations on the lines E E and F F respectively of Fig. V,
and Figs. IX and X are sectional elevations on the lines H H and K K respectively
of Fig. VI. In Figs. VII and VIII, and in Figs. IX and X with the exception of
the tube plates, parts behind the plane of section are not shown.
This form very closely resembles that already described and as most of the parts
are analogous to, and figured correspondingly to those already mentioned, they will
not be further referred to.
In this form the inner shell is a complete cylinder and the outer shell 14 as far as
it is required is also cylindrical, these shells being attached directly to the shell 1,
and the base 23 so dispensed with.
The cover or door 18 being now semi-circular it is not convenient to form the
air outlet in the manner already described in the case of Figs. I and II, and an air
outlet branch 24 is therefore provided.
In this arrangement as the steam is of high temperature, means are shown for
heating the air by the waste heat of the chimney gases before it enters the annular
space 15.
The air enters by the annular air inlet 2 surrounding the chimney 4 and is led to
the annular space 15 by the passage 26 formed on the outer shell of the air heater.
The inlet 25 is carried as high as may be thought desirable and, where necessary, .is
provided with a hood to prevent sparks passing into the air heater.
Referring now to Figs. XI, XII, and XIII, Fig. XI is an elevation, Fig. XII is
a plan and Fig. XIII a sectional elevation on the line L L of Fig. XI.
With the exception of the air outlet 24, the air heater is similar to that shown in
Figs. I and II.
27 is a connecting piece for attaching the air heater to the boiler; it communicates
with the interior of the boiler and the interior of the inner chamber of the air heater
by the openings 8.
We are aware that prior to our invention, air has been heated by being passed
through or over tubular or other heating surfaces heated by steam and we make no
broad claim to apparatus in which air is so heated, but :-
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is:
First. In a tubular air heater the combination of an inner chamber containing
steam as the heating medium, through which chamber pass a number of tubes divided
into stacks, with an outer shell forming an annular space or passage which partially
surrounds the said chamber, and covers or doors and division plates to direct a current
of air entering the annular space so that it passes through the same and then in
succession through each stack of tubes; substantially as and for the purposes set
forth,

page_text: Second. In apparatus for heating air the combination in one structure of a
steam generator with a tubular air heater, the latter consisting of an inner chamber
which forms part of the steam space of the steam generator, through which chamber
pass a number of tubes divided into stacks, an outer shell forming an annular space
or passage which partially surrounds the said chamber, and covers or doors and
division plates to direct a current of air entering the annular space so that it passes
through the same and then in succession through each stack of tubes; substantially
as set forth.
Third. The improved apparatus for heating air substantially as described and
illustrated in Figs. I and II.
Fourth. The improved apparatus for heating air substantially as described and
illustrated in Figs. III to X inclusive.
Fifth. The improved apparatus for heating air substantially as described and
illustrated in Figs. XI, XII and XIII.
Dated this 7th day of Juna 1880
SLOAN & LLOYD BARNES,
26, Castle Street, Liverpool, Agents for Applicants.
SLOAN & LLOYD BARNES,
26, Castle Street, Liverpool, Agents for Applicants.