An Improved Furnace-bridge for Economising Fuel and Preventing Smoke.
Year: 1890

page_text: Date of Application, 6th Mar., 1890
Complete Specification Left, 16th Oct., 1890-Accepted, 22nd Nov., 1890
PROVISIONAL
SPECIFICATION.
An Improved Furnace-bridge for Economising Fuel and Preventing
Smoke.
I WILLIAM AULD, Letterpress Printer Glasgow, and at present residing at 96 North
Hanover Street Glasgow in the County of Lanark, North Britain do hereby declare
the nature of this invention to be as follows:-
My said invention, relates to furnace bridges of every sort but chiefly relates to
steam boilers of the ordinary horizontal kind, and has for its object the economising
of the fuel used in said furnaces, and also the preventing of smoke from the same,
by the method of heating and applying the air, to the flame, gases, and smoke,
directly they have left the fuel, and while they are still in the end of the furnace.
I am perfectly well aware of the numerous patents that have been granted for
the above objects, but from whatever cause, the smoke still continues to be a source of
annoyance, and a positive evil, especially in large manufacturing cities and towns,
while the saving of fuel does not seem to have been such as to induce users of
power, to adopt them extensively. The suitableness of my invention to most of the
furnaces in use at the present time, I consider an important consideration; as well
as the ease with which it can be repaired, and kept in order, while the original cost
of the bridge, is so small, as to be a great recommendation for its use.
I will now describe my invention with the assistance of the accompanying sheet of
drawings, Fig. 1 is a front view, or elevation, in which two small auxiliary ports are
shown under the ends of the furnace bars a, a, a, to the right and left. Fig. 2 is a
vertical section, cut on the line A, B, D, F, Fig. 1, showing the air chamber, with a
side view of the centre port in the cover Fig. 4, and the angles of the same, by which
the air is directed, Fig. 3 is a plan on the line of the top of the furnace bars, a, a, a,
Fig. 4 is a plan of the cover G, that forms the top of the bridge, showing the
ports E, E, E, a side view of this cover, cut accross in the direction of the length of
the furnace is shown in the vertical section Fig. 2 at letter G, in which the side of
the centre port is seen; all the ports in this cover, have the same angle, only three
ports are shown in this cover, but I increase or reduce their number, to suit the size
of the furnace. In these drawings the same reference letters are used to mark the
same or similar parts, whenever they are repeated. I wish it to be understood that the
material of which this bridge is composed, is either all fire brick, and fire clay
mouldings, made to suit, which I consider preferable as best calculated to last, where
exposed to great heat, although parts of it might be made with iron, without injury
to my claim.
The object being to utilize the fuel, and also prevent smoke, I cause a thorough
combustion of all the gases given off the burning fuel on the furnace bars, without
lowering the temperature in the flues, by the following method. I make a bridge,
with an open port (B Fig. 1,) under the furnace bars, the air in passing along from
the front under the furnace door to the back part gets partly heated, entering the
port B, under the cover d (Fig. 3) which forms the roof of this port, the air
enters the chamber C, Fig. 3, which widens towards the top on either side, and
towards the front, as seen on the plan Fig. 3 e e and Fig. 2, ff, until it arrives at the
opening D Fig. 2, where the air erters the furnace immediately under the cover
(G Fig. 2) and over the end of the fuel on the fire grate a, Fig. 2, here the cover G
projects, from the front of the bridge, A A, to the inside edge of the port E Fig. 2,
about 4 inches (Figs. 1 and 2); at this point the air enters the ports E, (Figs. 2,
and 4,) confined by the deflecting front of the cover at F, which both directs the air,
and farther assists to heat the same, before entering over the cover G, where it passes
beneath the flame, which is running over the top of the cover, from the front of the

page_text: point F, and in the same direction, thoroughly mixing with the flame before it arrives
at the first tube b, by which the whole of the smoke and gases are kept in a state of
combustion; the tube might be supposed away without injury.
Having thus shown how the air is heated, before it arrives at the flame, I will now
explain the use of the two small auxiliary ports c, c, Fig. 1, shown to the right and
left under the bearer of the furnace bars. I find a very small supply of fresh air,
although not so highly heated, greatly assists in preventing any smoke, where the
flame is sufficiently strong, and this may be done without lowering the temperature of
the flues, so long as it is kept beneath the flame, which the hot air ports E, E, E, in
the cover G efficiently does: the small ports converge in the direction of the dotted
lines Fig. 1 c, c, so as to cause the air passing through them, to meet in the centre of
the flame, by which the flues are prevented from being cooled.
Dated this Fifth day of March 1890.
WILLIAM AULD,
Applicant.
COMPLETE SPECIFICATION.
An Improved Furnace-bridge for Economising Fuel and Preventing
Smoke.
I, WILLIAM AULD, Letterpress Printer, Glasgow, formerly residing at 96 North
Hanover Street, Glasgow, and at present residing at 120 Wellpark Terrace, Dennis-
toun, Glasgow, in the County of Lanark, North Britain, 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 :-
My said invention relates to furnace bridges of every sort, but chiefly relates to
steam boilers of the ordinary horizontal kind, and has for its object the economising
of the fuel used in said furnaces, and also the preventing of smoke from the same, by
the method of heating and applying the air to the flame, gases, and smoke, directly
they have left the fuel, and while they are still in the end of the furnace.
A furnace bridge made with my improvements is shown on the accompanying sheets
of drawings.
Fig. 1, is an elevation, (in my Provisional Specification, I showed on this elevation
two small auxiliary ports, c, c, which are not in these drawings, as I find they are not
required). Fig. 2, is a vertical section on the line A, B, D, Fig. 1, and Fig. 3, is a
plan on the line of the furnace bars; and at Fig. 4, the top part of the bridge, or
cover, made partly with iron, and partly with firebrick, is represented. In my
Provisional Specification I showed this cover made with fireclay, as "best calculated
to last where exposed to great heat;" but I find making part of this cover with iron
is more suitable to give strength. The remainder of the figures shows in detail the
different parts, which are fireclay mouldings made to suit," except that portion of
the cover made with iron, these I will use to describe how the bridge is put up; the
tube b is only to give clearness to the drawings.
The base of the port B, (Fig. 1), into which the air for combustion enters from
beneath the furnace bars, I make in one piece, but instead of building up the front of
this port level, I leave it with a steep incline towards the front, in order that it may
be easily kept clean. Fig. 5, 51, 51, shows three different views of this fireclay
moulding; Fig. 5, is a side view, 5 as seen from the back, and 5" is a plan of this;
there is a projection on each side about 2 inches at letter g, Fig. 5, and extends
from the back forwards about 6 inches, the angles shown at the upper part. of 5', is
made to suit the air chamber above, which gradually widens towards the top. This
moulding being placed on a previously prepared site, (A, Fig. 1), and built up behind,
and on each side, to the level of the highest edge, leaving a recess above letter g,
(Fig. 5), the same size as the projecting part, forms the bottom of the port B,
(Fig. 1). The cover Fig. 6, (an end view of which is seen at 6¹), rounded on the
under and inner edge, is now laid on the top front, of the building so made, forms
the upper part of port B, (Fig. 1), this gives a view of the bridge as seen at Fig. 3,

page_text: and shows the entrance to the air chamber at letter C. Figs. 7, 71, 71, forms the
left side of the air chamber, the point e of this moulding being inserted into the
recess, left above g. (Fig. 5"), with the projecting part resting on the cover 6, forms
one side, this inclines a little at the top at an angle, the edges of which is shown at
Figs. 71, 71, causes the air chamber to widen towards the top. Figs. 8, 81, 81, shows
the other side, with the angles as seen at Figs. 81, 81, two small catches shown on
the sides of these mouldings, about 3 inches from the front corners; these fit into
two grooves on the ends of Fig. 9, as seen at Figs. 91, 91, which are end views of
Fig. 9. Fig. 9, is now placed on the cover 6, (Fig 3), with the side mouldings a
little wide, to allow the catches to get into their grooves, the sides are then brought
close, and built on both sides and back, to keep them firm in their places; the
bridge is now ready for the cover G, Fig. 4, and shows the spaces at C, D, Fig. 2,
that contain the air before entering the furnace. In order to be easily handled,
have made Fig. 4, cover G, in several pieces. I will show how these are lifted on
to the bridge, so as to form one piece. Figs. 10, 11, are two side irons furnished
with a tail-piece about 5 inches long, to gripe the back part of the bridge, and are
laid on both sides, accross the bridge, in the direction of the length of the furnace ;
Figs. 10 and 11' are end views of these irons and shows the angles, that form the
outside edge of the cover, the centre portion of the cover is formed by the two
pieces 12 and 13, which, joined together at the middle by a catch that extends from
the one side, to the other side, an edge view of this is seen at Figs. 121, 13', the
portion of the cover 13 being lifted on to the front of the bridge first, and adjusted
in its place, the part that forms the back, is lifted up and moved over the front
portion until the catch falls into its place, when it makes one piece as seen at
12', 13¹.
The cover thus formed is now filled with firebrick previously made to fit, a rim
round the edge of the cover about in. by 3 inches deep, keeps these in their place.
The point of the cover, (F, Fig. 14), is now lifted into its place, which fits into
catches, shown at Figs. 10, 11, an end view of F, 14', shows the parts made to
fit these catches, the point F being made sufficiently long to give a bearing on each
end. The sides are now firmly built over, which finishes the bridge as seen at Fig. 1.
A slight curve upwards on the under side of the cover G, Fig. 131, I find useful in
keeping the port D, (Fig. 2), clean. The exterior of the point F is angular, but it
might be round, or any other convenient form, the interior, I make to suit the
direction of the flame. Having thus described how the bridge is made with fireclay
mouldings and iron,-but any other suitable material might do I will use Fig. 2 to
show how it acts in preventing smoke and saving fuel. The air passing from the
front under the furnace door and the fire bars, enters the port B, in the direction of
the arrows, rises through C into the air chamber and in passing on through D, is
exposed at this point to the strongest heat of the furnace; the projecting part of the
cover G, confining the air under the cover, and over the ends of the furnace bars,
arrived at the port E, it turns and strikes upwards, against the deflecting point F,
which is while the furnace is working-at a dull red heat, passing into the port E,
it becomes so rapidly hot, that it at once joins the flame, which is rising over the
front of F, and causes complete combustion of the smoke which is proceeding from
the furnace, so that nothing but the gases produced by the previous combustion is
allowed to enter the flues. It is very obvious that I will have to increase or diminish
the size of these mouldings to suit larger or smaller furnaces, as this bridge may
be made to suit any size of furnace, down to an ordinary washing house boiler-
when the cover might be in one piece-which I consider a thing very much wanted,
and would be a great benefit in some localities.
Having now particularly described and ascertained the nature of my said inven
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
The front port E, with or without divisions, by which the air entering the furnace,
from the front of the bridge, is prevented froin crossing the flame, and turned while

page_text: in the furnace, farther heated, and deflected by the point F, in the direction of the
flame, smoke, and gases. I claim none of the other parts separately, but the improved
construction and combination of the parts of a furnace bridge, as hereinbefore
described, and as shown in the accompanying drawings.
Dated this Fifteenth day of October 1890.
WILLIAM AULD,
Applicant.