Year: 1887

page_text: Date or Application, 19th Jan., 1887
Complete Left, 19th Nov., 1887
Complete Accepted, 20th Dec., 1887
[Communicated from abroad by PETER SMITH SWAN, of Calcutta, in the Empire of
India, Jute Manufacturer.]
I, SAINT JOHN VINCENT DAY of 115 St. Vincent Street, Glasgow, in the County
of Lanark, North Britain, Engineer and Patent Agent do hereby declare the nature
of this invention to be as follows :-
This Invention, which relates to improvements in furnaces used for heating air and
in the apparatus connected therewith, has for its object to increase the efficiency of
such furnaces by diminishing the loss of heat and thereby effecting economy in the
fuel employed.
In the improved furnaces the air used for combustion of the fuel is not drawn in
by the action of a tall chimney as hitherto, but it is drawn or forced thereinto by one
or more jets of steam or by the action of a blowing fan or the mechanical equivalent
thereof and thus the loss of heat due to the heating of the chimney and to the gases
therein is prevented.
In the improved furnaces the fuel is carried on the fire bars in an enclosed fire
chamber situated at the front or at one side of the air heating chamber and a short
chimney at the upper part of which has a damper at the bottom for the purpose of
making direct communication between the short chimney and the fire chamber when
starting the fire therein, and so soon as such fire is properly ignited this damper is
again closed.
The hot products of combustion from this fire are passed either
through a series of tubes, Alues or passages over which the air to be heated travels, or
they may be passed over the outside of such tubes, flues or passages through which
the air to be heated travels. The arrangement is such that the hot gases from the
fuel pass backwards and forwards through the said air heating tubes or air heating
spaces a sufficient number of times and at different levels to ensure the absorption of
the heat by the air which traverses into or through the heating spaces or tubes in the

page_text: opposite direction. Hinged dampers are provided to regulate the direction of flow of
the hot gases as well as the number of times they pass through the aforesaid flues or
spaces.
By this arrangement the air as it passes in is always getting gradually hotter
whilst the gases going out are always becoming gradually cooler.
The air heated in the improved apparatus hereinbefore described after it has done
its work in imparting its heat to rooms or other chambers or spaces is wholly or in
part returned by a pipe to the fire-place in which the combustion of the fuel takes
place and thus a continuous supply of hot instead of cold air is delivered to the
fuel.
T
For the purpose of protecting the tubo plates in which the air heating tubes are
held perforated slabs of fire-clay are placed over them whilst for modifying the action
of the intensity of heat from the furnace a fire clay screen or its equivalent is placed
between the fire bridge and the front tube plate.
The doors of the smoke box are lined with fire clay or equivalent refractory
material to prevent as much as possible the loss of heat by radiation.
The pipe through which the hot air is returned to the fuel in the furnace is
provided with one or more dampers for the purpose of preventing the escape of the
hot air when the furnace door is opened as such hot air might otherwise scorch the
attendant.
When the air used for combustion is drawn into the furnace a jet of steam from
any convenient source may be turned into the lower part of the short chimney or in
cases where a source of steam is not conveniently situated for being so used then a
sinal boiler is placed in the upper part or side of the fire place for generating steam
for this purpose.
Dadah 10L
CT
1007

page_text: Apparatus Connected therewith.
I, SAINT JOHN VINCENT DAY of 115 St. Vincent Street, Glasgow, in the County of
Lanark, North Britain, Civil Engineer and Patent Agent 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, which relates to improvements in furnaces used for heating air and
in the apparatus connected therewith has for its object to increase the efficiency of
such furnaces by diminishing the loss of heat and thereby effecting encomy in the fuel
employed.
In the improved furnaces the air used for combustion of the fuel is not drawn in
by the action of a tall chimney as hitherto but it is drawn or forced thereinto by one
or more jets of steam or by the action of a blowing fan or the mechanical equivalent
theroof and thus the loss of heat due to the heating of the chimney and to the gases
therein is prevented.
In the improved furnaces the fuel is carried on the firo-bars in an enclosed fire
chamber situated at the front or at one side of the air heating chamber and a short
chimney at the upper part of which has a damper at the bottom for the purpose of
making direct communication between the short chimney and the fire chamber when
starting the fire therein, and so soon as such fire is properly ignited this damper is
again closed. The hot products of combustion from the fire are passed either through
a series of tubes, flues or passages over which the air to be heated travels, or they may be
passed over the outside of such tubes, flues or passages through which the air to be heated
travels. The arrangement is such that the hot gases from the fuel pass backwards and for-
wards through the said air-heating tubes or air-heating spaces a sufficient number of times
and at different levels to ensure the absorption of the heat by the air which traverses into
or through the heating spaces or tubes in the opposite direction. Hinged dampers are
provided to regulate the direction of flow of the hot gases as well as the number of
times they pass through the aforesaid flues or spaces.
By this arrangement the air as it passes in is always getting gradually hotter whilst
the gases going out are always becoming gradually cooler.
The air heated in the improved apparatus herein before described after it has done
its work in imparting its heat to rooms or other chambers or spaces is wholly or in
part returned by a pipe to the fire-place in which the combustion of the fuel takes
place and thus a continuous supply of hot instead of cold air is delivered to the
fuel.
For the purpose of protecting the tube plates in which the air heating tubes are
held, perforated slabs of fire clay are placed over them whilst for modifying the
action of the intensity of heat from the furnace a fire-clay screen or its equivalent is
placed between the fire bridge and the front tube plate.
The doors of the smoke box are lined with fire clay or equivalent refractory material
to prevent as much as possible the loss of heat by radiation.
The pipe through which the hot air is returned to the fuel in the furnace is provided
with one or more dampers for the purpose of preventing the escape of the hot
air when the furnace door is opened as such hot air might otherwise scorch the
attendant.
When the air used for combustion is drawn into the furnace a jet of steam from
any convenient source may be turned into the lower part of the short chimney or in

page_text: cases where a source of steam is not conveniently situated for being so used then a
small boiler is placed in the upper part or side of the fire place for generating steam
for this purpose.
In order that this Invention may be properly understood and readily carried into
effect, I will now proceed to describe the drawings hereunto annexed.
Figure 1, of the annexed drawings, is a vertical section of an apparatus for heating
air constructed according to this Invention.
Figure 2, is a transverse section of the same.
Figure 3, is a horizontal section on the line a, b, Figures 1 and 2.
Figure 4, is a part transverse section on the line c, d, Figure 1, and,
Figure 5, is an elevation of the smoke-box end of the apparatus.
As shown by these Figures. the furnaco for heating the air consists of an outer
casing of fire-brick or other material marked A.
The fire-grate on which the fuel for generating the heat rests is marked B, Figures 1
and 3, and the hot gases escaping from the fire grate B, pass over the bridgo C, and
through the openings in the screen D, into the upper series of tubes E. On arriving
through the upper series of tubes E, the hot gases pass downwards into and through
the next set of tubes marked F, thence downwards and again through the next set of
tubes marked G, on leaving which they pass through the lowest set of tubes marked H,
escaping into the side flues I, thenco into the chimney marked L. The chimney L, is
provided with a sliding damper M, which, when opened by drawing the damper out-
wards permits a free communication between the fire grate B, and the chimney L,
and when shut closes that communication. Freo communication between the
chimney L, and fire-grate takes place when the fire is lit from the grato B, and is
allowed to continue until the said fire thereon is well lit or burning when the commu-
nication by means of the damper M, is closed. In the upper part of the furnace B,
a small boiler N, is or may be placed for the purpose of creating a steam blast in the
chimney 1, the cock O, in the pipe O, being opened to any degree required to
regulate the force of such blast.
In place of using the boiler N, for generating the steam for this last mentioned
purpose steam may be supplied to produce a jet or blast in the chimney from any
suitable source or instead of the vertical boiler N, a small horizontal boiler P, as
shewn in horizontal section at Figure 3, may be substituted, a flue P¹, being taken off
from the furnace B, for conveying heat to the said boiler E.
The air to be heated traverses over the exterior of the pipes H, G, F, and E, at right
angles to the direction of the length of the said pipes as shewn by the arrows in
Figure 2, entering cold at the bottom of the chamber through the openings Q, and
traversing gradually upwards by a backwards and forwards ascending motion as in-
dicated by the arrows in Figure 2. From this arrangement it will be seen that
whilst the gases escaping from the fire on the grate P, in descending the several sets
of flues E, F, G, and H, become gradually cooler, the cold air passing in through
passage Q, and ascending over the outside of the said pipes becomes gradually
hotter until it reaches its point of escape at R, whence it is taken away for the pur-
pose for which the air so heated is to be used, whether it be for heating a building
or other purposes.
On referring to Figure 1, it will be observed that the hollow spaces outside the
front and back ends of the tubes E, F, G, and H, are fitted with hinged dampers S, by
which the motion of the heated gases through the pipes is regulated. Being fitted
with hinges the proportion of gases passing through the tubes and their direction of
motion there-through may be varied from time to time as desired. It will also be
observed with reference to Figure 2, that the direction of motion of the air to be
heated is regulated by the horizontal dividing plates T.
From what has been hereinbefore stated the gases escaping from the furnace B,
for heating the air are caused to pass through the heating apparatus from its upper
part downwards and the air to be heated is caused to pass from the lower part of
the apparatus upwards. It is to be understood however that these directions of
motion both of the heating gases and the air to be heated may be reversed.

page_text: After the air to be heated has done its work either in heating rooms or chambers
or as otherwise applied for heating purposes the whole or portion of it is returned into
the space beneath the fire-grate B, by the discharged flue being connected to the
flue U, Figure 1. This flue U, is connected by an ascending passage to the hollow
hinged joint V, of the fire-door V, whence it is discharged into and escapes through
perforations in the inner part of the said chamber to the fuel into the spaces both
below and above the fire-grate B, and thus air more or less heated is or may be
supplied to the fuel burning on the fire-grate B.
In place of causing the circulation of the hot gases and air through the apparatus
to be effected by the drawing or inducing action of the steam jet in the chimney L,
the circulation may be effected by force draught, such as that of a drawing air fan
or compressed air pump.
As shewn at Figure 5, the smoke-box end of the heater which is the end W, in
Figure 1, is provided with doors W₁, Figure 5. These doors are preferably hinged and
provided with latches at the centre for operating them in sections as shewn by
transverse lines at Figure 5, a latch and catch W³, being applied to each such section
of doors. These doors are provided for the purpose of obtaining access to the several
tubes E, F, G. and El, in order that a brush or other instrument may be inserted for
cleaning out the tubes in the manner well understood. The interior of the door W,
is lined with slabs of fire clay for the purpose of conserving heat in the air heater, and
the tube-plate, whereinto the ends of the tubes nearest the furnace are fixed, is
protected by a perforated fire-clay screen D, to prevent the heat from the fire on the
grate D, from acting too fiercely upon the said tubes.
In place of using plain cylindrical tubes as hereinbefore described, flange tubes may
be used as shewn at Figure 6, with the view of increasing the heating surface.
At Figure 7, of the annexed sheets of drawings, I have shewn how my air heater
may be combined with an ordinary multitubular boiler of the locomotive type which
may be either portable or stationary, and at Figure 8, a plan of the same. In these
Figures the part marked A, is the fire grate whereon the fuel is burnt for heating the
air-heater. The fire box of the boiler is not shewn in these Figures but the tube-plate B,
in Figure 7, represents the end of the boiler with the tubes leading from the fire-box
into the smoke-box C. In starting this apparatus into operation the heated products
of combustion pass through under the flue D, of the heater and up through an
opening in the end thereof through the lower tubes E, on escaping from which the
heated products pass through the tubes G, thence returning by the tubes H, and
again successively backwards and forwards through the tubes I, J, and K, (the
directions of flow being regulated by hinged dampers as shewn more particularly in
Figure 1) whence they are discharged into the flue L, leading into the chimney M.
A plate leads from the upper part of the flue L, and closes over the top of the smoke-
box B, as shewn at Figure 7. This plate is provided with a damper or valve N, which
open until steam is raised in the boiler so that the products of combustion from the
fire-box of the boiler on escaping from the tubes in to the smoke-box C, pass directly
through the open valve or damper N, up into the chimney M. When steam however
is raised in the boiler the valve or damper N, is closed and the waste products of
combustion escaping through the heater from the fire box of the boiler escape directly
into the lower flues E, and follow together with the products of combustion from the
fire-grate A, through the tubes G, H, I, J, and K, backwards and forwards to the
flue L, whence they pass into the chimney M. In this way the waste heat escaping
from the flues of the boiler is utilized for heating the air passing through the air heater
and the economy of fuel is effected. A hinged or equivalent door O, is provided for
the purpose of opening or closing communication between the smoke box C, and the
air heater.
is
To enable the tubes both of the boiler and the heater to be directly got at for being
cleaned by tube brushes or their equivalent on the opening of the door P, of the smoke
box C, which is hinged at Q, for the purpose of being opened and closed this door is
by preference placed at an angle so that when opened the tubes of both the boiler and
the heater are at once accessable for cleaning purposes. The chimney M, of the boiler

page_text: is or may be provided with the usual binged arrangements for folding it down over
the top of the boiler as is usual with portable engines. Of this arrangement a plan is
shewn with the hinge at Figure 9, and in elevation at Figure 10, with the usual
damper slide R, fitted thereto.
In Figures 7 and 8, I have not thought it necessary to shew the wholo construction
of the air heater as that will be understood from the description hereinbefore given in
reference to the preceding Figures and it is to be understood that the direction of the
passage of the air through the heater is similar to that hereinbefore described. The
air may be either forced through the fire grate A, up through the heater by a fan or
pump not shewn in the drawings or it may be drawn therethrough by a steam jet S,
in the chimney as desired.
At Figure 11, I have shewn a vertical boiler A, combined with the air heater B, for
the purpose of utilizing the waste heat escaping from the boiler after steam has been
raised therein.
I have not shown the heater B, in full as its construction and arrangement will be
obvious and is similar to that of the heater hereinbefore described.
A door or damper C, or the mechanical equivalent thereof is fitted in the chimney D,
which whilst steam is being raised in the boiler A, is allowed to lie vertical so that
there is free communication for the products of combustion of the boilor up through the
chimney D, but as soon as steam is raised the door C, is shut into the position shewn
at Figure 11, so as to close the chimney, in which case the products of combustion
pass backwards and forwards through the heater B, as indicated by the arrows and
thence escape into the chimney D, at a higher level, namely at the opening E.
Figure 12, is a horizontal section of the arrangement through the heater B. In the
chimney D, there is provided a steam jet F, for drawing the products of combustion
through the heater but in place of this arrangement, force draught may be used by
means of a fan or pump coupled to the pipe G, leading to the fire-grate contained
within the enclosing chamber H, which is provided with a light fire or feeding
door I.
Having now particularly described and ascertained the nature of the said Inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
First. The air heater in which economy of fuel is effected by making the air heating
flues, pipes or chambers of large area or heating surface relatively to the size of the
furnace, so that the said flues, pipes or chambers may be capable of absorbing the
whole of the heat of the products of combustion passing through or around them, and
in which heater the draught which would otherwise fail under such circumstances is
maintained artifically by means either of a steam jet in the furnace or by air forced
into the furnace, the said air upon being utilized for heating rooms or other chambers
being wholly or partly returned to the furnace by a fan or blower or by the induced
draught caused by the steam jet in the funnel, the whole constituting a regenerative
system of air heating substantially as herein before described and shown upon the
annexed drawings.
Second. The combination of the air heater with a steam boiler so that the waste
heat escaping from the steam boiler becomes partly or wholly the source of heat
for heating the air substantially as described and shewn on the annexed sheets of
drawings.