Improvements in and relating to the Supplying of Air to Steam Boiler and other Furnaces.
Year: 1899

page_text: Camalaka
Date of Application, 9th Mar., 1899
PROVISIONAL SPECIFICATION.
Improvements in and relating to the Supplying of Air to Steam Boiler
and other Furnaces.
I, JAMES MUNRO, of Tillanburn, Holytown, Lanarkshire, Engineer, do hereby
declare the nature of my invention to be as follows:-
-
This invention has reference to and comprises improvements in and relating
to the supplying of air to steam boiler and other furnaces and which consist
essentially in appliances for admitting and regulating the supply of air and of an
improved blower by which air currents may be induced by the action of steam
jets, for supplying air to steam boiler or other furnaces.
In carrying into practice the improvements of this invention as applied to a
horizontal steam boiler furnace, a closed ashpit is used fitted with a closing hinged
door lying at an angle, so as to keep the ashpit closed by its own weight. Above
this closing door a valve plate consisting of a plate formed with rectangular
openings towards its centre part, and an opening at each end is fitted transversely
across the ashpit and a covering plate lying at a reverse angle is bolted on
outside, the whole forming an air chamber or casing in communication with the
outer air or with the air duct from any source of supply of pressure air, the air
being preferably led down from above and on each side of doorway, the main duct
being provided with a sliding door.
The openings, towards the centre of valve plate allow air to pass into the closed
ashpit under the grate bars to feed the fire and form gas, while the end openings
allow the air to pass into chambers formed on each side of the fire whence it is
discharged above the incandescent fuel to burn the gas and so effect perfect com-
bustion of the fuel.
An opening is formed at each end of covering plate, covered in the inside by a
flap valve which may be simply a piece of asbestos cloth or the like. These
openings allow air to enter and cool the side air passages when the forced blast. is
shut off.
The proportionate regulation of the admission of the air to the under side
of the grate bars, and to the side air chambers.. is effected by two sliding valves.
each formed with a rectangular opening and sliding on the face of the inclined
valve plate.
These sliding valves can be moved to and fro so as to open and allow more
air to pass through the centre openings and at same time less through side
openings by closing these, or vice versa, to close the one set of openings and open
the other by the following means. A lever within the air chamber is actuated
by a spindle secured to its centre and passing to the outside, in some cases in
an inclined position, and has a pendent arm secured to its outer end which engages
with a toothed quadrant to hold it in any desired position. The ends of this lever
are each connected to one of the sliding valves by a connecting rod engaging
with a pin on same. The pin of one sliding valve being near the top and of the
other near the bottom, so that any movement of the lever moves the sliding valves
In opposite directions.

page_text: The side air chambers which lead the air to ton of fire are formed by fitting
cast iron box plates one on each side of the fire and extending back to the
bridge formed at the lower sides with a recessed part and a turned over edge at
top, and having a projecting part at one end which fits below the dumb plate of
the furnace. The recessed parts of these plates form the air chambers when boxed
in by the covers to be described. These covers are plates which have a turned
over edge at top by which they are suspended on the turned over edges of the
box plates and which are formed with a number of studs to keep them apart from
the box plate and also act as baffles to retard or break the force, of the air current
while their lower ends rest against lower Hat portions of the box plates. The
cover plates have each a transverse rib or projection on its outer face near the
bottoni, so that the side bars of the grate hold them in position by means of these
ribs and have also a transverse rib on the inner face at the bottom and are further
formed with a series of small openings at top by which the air passes within the
furnace to mix with the products of combustion above the fire.
In this arrangement the air may be supplied or induced by means of any air
propelling appliance or when a long chimney is available sufficient natural draught
will be developed to induce the required current of air.
In a furnace fed with air below the bars and from the sides as described the
door if of ordinary form would become red hot from the want of a sufficient
draught of air through it to keep it cool. The door is therefore made hollow and
formed with studs on its inner wall to act as baffles and has openings formed at
the upper part of its inside wall, while a small hole fitted with a very short tube
is formed at the lower part of its hinged side. When the door is shut this short
tube connects with a hole leading from the air duct when pressure air is used so
that a constant stream of air passes through the door. When the supply of
pressure air is shut off a sliding grid fitted at the bottom of the door in front
can be opened to allow air to enter.
The door has an eyehole formed in it by which the state of the fire can be
ascertained without opening it and the supply of air regulated accordingly.
The improved blower which is used to supply pressure air to the furnace as
above arranged and which is also applicable to other furnaces is formed as a
cylindrical casing in two parts screwed together at one end and which has an
annular steam chamber around it between the two wall parts a branch pipe being
fitted to supply the steam, from any source of supply. A cylindrical liner is fitted
within this casing and is formed with a flange making a steam tight joint with
the end of the casing.
A hopper shaped mouthpiece is screwed on to the top of the liner and retained in
position by a pinching screw. The bottom of the mouthpiece rests on a short
spiral spring within an annular recess formed around the inside of casing at the
same end and this recess is partly filled with packing and a washer over same.
The liner is thus held in steam tight contact with the casing end by the action
of the spring.
Holes, preferably three in number, which number may be increased for large
sizes, are formed longitudinally through the end of casing forming outlets for the
steam from the annular chamber, and holes of the same size and at distances to
coincide, with those in the casing are formed in the flange of the liner. A series
of holes of gradually decreasing size are formed at spaced distances apart from the
larger holes, any set of three of which may be made to coincide with the holes in
the casing end by turning the liner around by means of its mouthpiece acting
as a hand wheel so that the volume of steam allowed to issue may be varied. at
pleasure. A small clip hinged to the mouth piece engages with notches on a
raised edge of casing to hold the liner in any desired position. This blower is or
may be inserted within a larger air duct or pipe and held there by any ordinary
supporting means such as radial-webs. The steam passing through the holes at
a high speed acting on the annular current of air outside and the cylindrical
volume inside of the blower induces a strong blast.

page_text: A tube of less diameter with bevelled or trumpet mouth ends is secured within
the larger air pipe or duct to reduce its diameter at the part where the steam
and air from the blower enters it.
A blower somewhat similar to that already described may be inserted in the
ordinary flue or it may be a special flue leading from the furnace to the chimney
which may be a short one to cause a draught through the furnace by suction
action, and this blower may be used alone or in combination with a blower or
other source of supply of pressure air forcing air in at front of furnace. This
secondary blower may be formed as an annular steam chamber placed within the
flue and supplied with steam from the boiler by a side branch and having a series
of steam outlets formed in its face and a regulating ring plate pierced by series of
holes decreasing in diameter fitted to work on its face so that the holes of the
desired' diameter may be brought in front of the steam outlets. This may be
effected by a handle working through a slot in the flue or by quadrant and pinion
mechanism.
Dated the 8th dow of March 1800
W. R. M. THOMSON & Co.,
96, Buchanan Street, Glasgow, Agents.
COMPLETE SPECIFICATION.
Improvements in and relating to the Supplying of Air to Steam Boiler
and other Furnaces.
I, JAMES MUNRO, of Tillanburn, Holytown, Lanarkshire, Engineer, do hereby
declare the nature of my invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement in writing, reference being made to the accompanying drawings.
This invention has reference to and comprises improvements in and relating
to the supplying of air to steam boiler and other furnaces, and which consist
essentially in appliances for admitting and regulating the supply of air, and of an
improved blower by which air currents may be induced by the action of steam
jets, for supplying air to steam boiler or other furnaces.
And in order that my said invention may be properly understood I have here-
unto appended three sheets of explanatory drawings in which the same reference
letters are used on the same or equivalent parts in all the figures where shown.
Figure 1, on Sheet 1, is a front elevation partly in section of a double flued
Lancashire boiler as fitted with my improvements, Figure 2, is a side sectional
elevation of the furnace end of same and Figure 3, is a plan of one of the furnaces
shown to an enlarged scale.
Figure 4, a detail view of the box plate B
Figure 5, is a detail view of one of the studded cover plates B'.
Figures 6 and 7, are respectively a sectional elevation of my improved air
blower or propeller and an inverted plan of the perforated plate G
Figure S, is a sectional view of my improved blower in a modified form.
Figures 9 and 10, are two views at right angles illustrating the method of
rotating the plate G6, by worm screw mechanism.
Figure 11, is a view of part of a blower designed for use where the steam jets
required are constant in volume but capable of adjustment to any desired volume.
Figures 12 and 13, on Sheet 2, are respectively a side sectional elevation and
a front elevation partly in section of a well known type of water tube boiler, while
Figures 14 and 15, are respectively a sectional elevation of an upright boiler and
a plan of the furnace of same as fitted with my improvements.

page_text: Figures 16 and 17, on Sheet 3, are respectively a sectional side elevation and a
sectional plan of the firebox of a boiler of the locomotive type while Figure 18,
is a side sectional elevation of an egg-ended boiler and its flue shown broken away
and Figure 18 is a partial sectional plan of the furnace all as fitted with my
improvements, and Figure 19, is a side sectional elevation of a small furnace for
use for heating water in an open boiler or a kettle or for such like purposes
arranged with part of my improved appliances.
Figure 20, on Sheet 1, is a detail view of a furnace door.
Referring to Figures 1 to 5, of these drawings:-
In carrying into practice the improvements of this invention as applied to each
of the furnaces B, of a horizontal steam boiler A, such as is illustrated by
Figures 1, 2, and 3, a closed ashpit C, is used fitted with a closing hinged door C¹,
preferably lying at an angle, so as to keep the ashpit closed by its own weight.
Above this closing door C', a valve plate consisting of a plate D, formed with
rectangular openings D¹, towards its centre part, and an opening D², at each end,
as shown in Figure 3, is fitted transversely across the ashpit C, and a covering
plate E, lying at a reverse angle is bolted on outside, the whole forming an air
chamber or casing E', in communication with the outer air or with the air duct F,
from any source of supply of pressure air, that shown being my improved blower G,
the air being preferably led down from above and on each side of furnace door H,
the main duct F, being provided if necessary with a sliding door, not shown in the
drawings, or the air may be led in any suitable manner into the chamber E¹.
The openings D', towards the centre of valve plate D, allow air to pass into the
closed ashpit C, under the grate bars B', to feed the fire and form gas, while the
end openings D², allow the air to pass into chambers 6, formed on each side of the
fire whence it is discharged through openings b. above the incandescent fuel.
to burn the gas and so effect perfect combustion of the fuel, which may be solid,
liquid or gaseous or a mixture of these.
An opening E, is formed at each end of covering plate, covered in the inside
by a flap valve E³, which may be simply a piece of asbestos cloth or the like.
These openings allow air to enter and cool the side air passages when the forced
blast is shut off.
The proportionate regulation of the admission of the air to the under side of
the grate bars 11, and to the side air chambers b, is effected by two sliding
valves d, d, each formed with a rectangular opening . and sliding on the face of
the inclined valve plate D.
These sliding valves d can be moved to and fro so as to open and allow more
air to pass through the centre openings D¹ and at same time less through
side openings 12, by closing these or vice versa, to close the one set of openings
and open the other." As illustrated, the side openings D, are both closed and all
the openings D are open, but by moving the sliding valves the side openings De
may be fully opened and the openings D¹, closed, or any mid position may be
obtained, by the following means. An oscillating lever, within the air
chamber E, is actuated by a spindle secured to its centre and passing to the
outside, in some cases in an inclined position, and which has a pendent arm
secured to its outer end which engages with a toothed or notched quadrant d to
hold it in any desired position. The ends of this lever are connected to the
sliding valves d, d, by connecting rods d, engaging with pins on same. The pin
of one sliding valve is near the top and of the other near the bottom, so that
any movement of the lever de moves the sliding valves d, d in opposite directions.
The side air chambers which lead the air to top of fire are formed by fitting
cast iron box plates which may be of the form shown at B2 Figure 1 and by
Figure 4, or of the form shown at 133 Figure 1 which obviates the space left
between the plate B and the shell of the furnace, and these plates B2 or B³ may
be formed all in one piece or in sections. one being placed on each side of the fire,
extending back to the bridge B and formed at the lower side with a recessed
part. The recessed parts of these plates form the lower part of air chambers b

page_text: when boxed in by the covers to be described. These covers are plates which may
be of the form shown at B and by Figure 5, or of the form shown at B5 and
which have a turned over edge at top by which they are suspended on the top
edges of the box plates and are formed with a number of studs B to keep them
apart from the box plates and also act as baffles to retard or break the force of
the air current and so heat it, while their lower ends rest against lower flat portions
of the box plates B or B. When the form of cover plate shown at B5, Figure 1
is used the concavity is preferably filled in with ganister or fireclay as indicated in
the drawing. Each of these cover plates B or B has a transverse rib 18 or
projection on its outer face near the bottom, so that the side bars of the grate
hold the series in position by means of these ribs and has also a transverse rib B
on the inner face at the-bottom. They are further formed with a series of small
openings at top by which the air passes within the furnace B to mix with the
products of combustion above the fire.
In this arrangement the air may be supplied or induced by means of any air
propelling appliance or when a long chimney is available sufficient natural draught
can be developed to induce the required current of air, in which case the duct F
and the covering plate E can be dispensed with.
as
In a furnace fed with air below the bars B' and from the side openings
described, the door H if of ordinary form would become red hot from the want
of a sufficient draught of air through it to keep it cool. The door H is therefore
made double, hollow, and formed with studs Hi Figure 2 on its inner wall to act
as baffles and openings H2 are formed at the upper part of its inside wall, while
a small hole. fitted with a very short tube H³ is formed at the lower part of its
hinged side. When the door is shut this short tube H³ connects with a hole H5
leading from the air duct F, when pressure air is used so that a constant stream
of air passes through the door all as illustrated more particularly by supple-
mentary Figure 20. When the supply of pressure air is shut off a sliding grid,
not shown in the drawings, but which may be fitted at the bottom of the door H
in front can be opened to allow air to enter and circulate upwards to the
openings H³.
The door has an eyehole H formed in it fitted with any ordinary cover by which
the state of the fire can be ascertained without opening the door and the supply
of air regulated accordingly.
The improved blower G one form of which is illustrated by Figures 6 and 7
and which may be used to supply pressure air to the furnace B as above arranged
through the duct F and which is also applicable to other forms of furnaces. or
purposes is formed as a cylindrical casing in two parts G1, G2, screwed together
at one end and which has an annular steam chamber G3 around it between the
two wall parts, a branch pipe G, being fitted to supply the steam from any
source of supply. A cylindrical liner G is fitted within this casing and is formed
with a flange G making a steam tight joint with the end of the casing.
A hopper shaped mouthpiece G is screwed on to the top of the liner-G³ and
retained in position by a pinching screw g. The bottom of the mouth piece G
rests on a short spiral spring or springs gl within an annular recess formed around
the inside of casing at the same end and this recess partly filled with packing g
and a washer g³ over same. The flange G of the liner G is thus held in steam
tight contact with the casing end by the action of the springs gl.
Holes preferably three in number, but which number may be increased for
large sizes, are formed longitudinally through the end of casing forming outlets
for the steam from the annular chamber G³, and holes of the same size. and at
distances to coincide with those in the casing are formed in the flanges of the liner.
A series of holes of gradually decreasing size are formed at spaced distances
apart from the larger holes g any set of three of which may be made to coincide
with the holes in the casing end by turning the liner around by means of its
mouthpiece acting as a hand wheel. so that the volume of steam allowed to issue
may be varied at pleasure while always passing at the full pressure. A small

page_text: of
clip hinged to the mouth piece G engages with notches on a raised edge
casing, to hold the liner in any desired position. This blower Gis or may be
inserted within a larger air duct or pipe such as shown at F Figures 1 and 2
and held there by any ordinary supporting means such as radial webs or rods
the steam inlet branch acting as one support. The steam passing from the
boiler by the pipe F3 and through the holes of the blower at a high speed acts
the annular current of air outside and the cylindrical volume inside of the
blower and induces a strong blast.
1
on
A tube. F¹ of less diameter with bevelled or trumpet mouth ends is secured so, as
to be adjustable in position within the larger air pipe or duct F to reduce its
diameter at the part where the steam and air from the blower enters it.
This duct F may be carried to, or be connected to a branch pipe from, any
part to carry off bad smells, vapour, or noxious gases and deliver them within the
furnace to be destroyed, or carry air previously heated, it may be by waste heat.
Figure 8 illustrates another form of my improved blower in which the annular
steam chamber is formed as a casting having the holes formed through its lower
face and the series of holes are formed in a disc plate Go secured to the
lower end of a spindle passing up through the centre of the annular steam
chamber G and caused to hold the disc plate G6 in steam tight contact with the
lower face of the steam chamber by the screw nut secured to the spindle by a
pinching screw and resting on packing material or a spring in the recess on top
of steam chamber. A conical cap g' is secured to the top of the spindle G8 and the
catch holds it in position by engaging with notches on the top edge of the
steam chamber G³. In this figure nipples g10 are shown as inserted in the disc
plate Go for the better direction of the steam jets.
Figure 7 illustrates an arrangement in which square holes are formed in the
face of steam chamber G³, and in the plate or flange Go instead of a series of
holes of various sizes and the opening for the passage of steam is regulated by the
rotation of the plate G enlarging or decreasing the size of same.
Figures 9 and 10 illustrate a method of rotating the flange or disc plate G which
for large sizes may be an annular plate by means of a worm screw I carried by
brackets I and working into notches or teeth cut in the edge of the plate G³,
Is being one of a series of supporting pulleys which hold the annular perforated
plate G against the lower face of steam chamber G.
Figure 9 illustrates a bulbous form of blower, having an internal steam
chamber G and regulating plate G which may be connected to a steam pipe and
used in the same manner as the other forms described.
Figure 1 illustrates a form of annular steam chamber G³ suitable for large
sizes and when the volume of steam desired to issue therefrom is constant. In this
case nipples g10 of the dimensions to give the desired volume are inserted in the
lower face of the steam chamber and are interchangeable with others so as to
regulate the volume of steam as desired.
=
Figures 12 and 13 on Sheet 2, being respectively a side sectional elevation and
a front elevation partly in section of a well known type of water tube boiler
illustrate the application of my improvements to the furnaces of such boilers.
Part of the current of air induced within the air duct F by the blower G
supplied with steam from the steam drum of the boiler by the pipe F2 passes down
the duct enters the side passage which is carried round the back of the
furnace and along the other side and issues to mix with the gases of the fire
through the series of openings 61 to effect complete combustion, while part of the
air enters the closed ashpit C by the passage D¹ to feed the fire from below.
The regulation of the proportionate amount of air admitted above and below the
fire is regulated by the valve plate d which may be suspended by the rod de in
a balanced manner from a counterweighted chain passing over a pulley, or any
other suitable device may be adopted to hold it in the desired position, the raising
of the valve plate acting to close the upper passage band proportionately open

page_text: the lower one D or vice versa. The furnace door H is preferably of the same
construction as that previously described in reference to Figures 1 and 2.
Figures 14 and 15 being respectively a sectional clevation and a plan of an
upright boiler show the application of my improvements to this class of boiler.
In this case the furnace B is preferably formed square and fitted with studded
cover plates B such as described in reference to Figures 1, 2, and 3, hung by their
turned over upper edges on three sides of a box frame B32 forming the upper
part of the air chamber receiving air from a duct leading an induced current
of air partly to this air chamber and partly to the closed ashpit C below the
furnace, and this air current may be induced by means of my improved blower
fitted within the duct F. The proportionate regulation of the amount of air
admitted above and below the fire is effected by means of the grid or valve plate ])
formed with openings D1 and D2 and the sliding valve plates d d actuated by the
arm and spindle all in a manner similar to that described in reference to
Figures 2 and 3.
The partitions C² separates the closed ashpit from the air
chamber b.
Figures 16 and 17 illustrate the application of my improvements to the
furnace of a boiler of the locomotive type, Figure 16 being a sectional elevation
of the fire box end and Figure 17 a sectional plan of the furnace. The arrange-
ment of the parts is in this case practically the same as that described in reference
to Figures 14 and 15 and the reference letters denote the same or equivalent parts.
The cover plates 13* in this case are hung on the top of a plate B2 bolted or
rivetted to the shell of the furnace.
A
Figure 18 shows my improvements applied to an egg-ended boiler, the arrange-
ment of the furnace and air directing passages being similar to that described
in reference to Figures 12 and 13 and the reference letters denote the same or
equivalent parts. Figure 18 shows the arrangement of the air exits the tapered
openings being preferably formed by using bevelled bricks. Figure 18 also
illustrates the application of my improved blower for the purpose of inducing a
draught for drawing off the products of combustion from the furnace flue.
blower G being in this instance inserted in a flue leading from the furnace
flue to the chimney K or it may be in the ordinary flue or chimney, and supplied
with steam from the boiler by the tube FX, and this blower may be used alone
or in combination with a blower or other source of supply of pressure air forcing
air in at the front of the furnace. This secondary blower may be of any of the
forms shown and described and the regulation may be effected by a handle g
working through a slot in the flue or by quadrant and pinion mechanism or
the worm screw mechanism shown and described in reference to Figures 9 and 10.
Dampers or sliding doors J, K, are inserted in flue and at the entrance to
chimney K for the regulation of the draught.
Figure 19 illustrates an appliance which may be portable fitted with my
improvements for heating a boiler, kettle or for other boiling or heating purposes
and which consists of a casing L containing a furnace 1 formed with duplex
walls LL, the inner wall L being formed with projecting studs L and air
exit holes b¹ and so forming the equivalent of the cover plates B. Pressure air from
a fan or other source of supply enters by the duct F and passes into the closed
ashpit C and to the air circulating chamber b. The proportionate quantity of air
admitted being regulated by the valve plate d raised and lowered by the spindle d³
to open and close the passages D¹ De.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
First. In steam boiler and other furnaces the construction or arrangement
and combination of the parts of appliances for inducing air currents and supplying
air in a regulated manner above and below the furnace bars and fuel to produce

page_text: J
perfect combustion of the gases, substantially as herein described and illustrated
by the accompanying drawings.
Second. In steam boiler and other furnaces the construction and arrangement
of air ducts, leading air by a series of air exits to the furnace above the fuel, and
to the closed ashpit beneath, regulated by the movements of valves, substantially
as herein described and illustrated by the accompanying drawings.
Third. In steam boiler and other furnaces the construction and arrangement
or combination of box plates B2 or 13 cover plates B or B grid or valve plates D
and sliding valves d for the purpose of supplying air in a regulated manner above
and below the furnace bars, substantially as herein described and illustrated
by Figures 1 to 5 and 14 to 17 of the accompanying drawings.
Fourth. In combination with a system such as described for supplying air in
a regulated manner to steam boiler and other furnaces the formation within the
brickwork of air chamber or passages with tapered outlets 61, substantially as
described in reference to and by way of example illustrated by Figures 12, 13;
and 18 of the accompanying drawings.
Fifth. In steam boiler and other furnaces in combination with a system of
supplying air in a regulated manner above the fuel and below the furnace bars
the use of steam air blowers or propellers constructed and arranged substantially
as herein described and illustrated more particularly by Figures 6 to 10 of the
accompanying drawings.
Sixth. The construction and use of steam air blowers or propellers having
annular or central steam chambers with outlet orifices and perforated covering
plates or discs also perforated for the regulation of the volume of steam emitted,
substantially as herein described and illustrated by Figures 6 to 10 of the accom-
..panying drawings.
:
Seventh. Steam air blowers or propellers constructed and arranged, substantially
as herein described and illustrated by Figures 6 and 7 of the accompanying
drawings.
Eighth. Steam air blowers or propellers constructed and arranged substantially
as herein described and illustrated by Figure 8 of the accompanying drawings.
Ninth. In steam boiler and other furnaces the construction of a double furnace
door with an inner air circulating chamber in communication with pressure air
duct, substantially as herein described and illustrated more particularly by
Figure 20 of the accompanying drawings.
Tenth. For the purpose of regulating the supply of air above and below the
fuel in steam boiler and other furnaces the construction and arrangement of the
grid or valve plate D, and sliding valve plates actuated by lever mechanism
substantially as herein described and illustrated by Figures 1, 2, 3, 15, and 17 of
the accompanying drawings.
Eleventh. Portable furnaces in which the supply of air above and below the fire
grate is regulated to effect complete combustion constructed and arranged sub-
stantially as herein described in reference to and illustrated by Figure 19 of
the accompanying drawings.
Twelfth. In steam boiler and other furnaces the regulation of the proportionate
admission of the air both above the fuel and below the grate to produce perfect
combustion by one movement of a lever or handle, substantially as herein described
and by way of examples shown in Figures 1 to 3 and 12 to 19 of the accompanying
drawings.
DX