Improvements in Apparatus and Appliances for Promoting More Perfect Combustion of Fuel in the Furnaces of Steam Boilers.
Year: 1889

page_text: Date of Application, 16th Nov., 1889
Complete Specification Left, 16th Aug., 1890-Accepted, 20th Sept., 1890
PROVISIONAL SPECIFICATION.
Improvements in Apparatus and Appliances for Promoting More
Perfect Combustion of Fuel in the Furnaces of Steam Boilers.
I, JAMES MELLAR of 34 Palmer Road, Darnall, near Sheffield, in the County of
York, Mechanical Engineer, do hereby declare the nature of my said invention for
"IMPROVEMENTS IN APPARATUS AND APPLIANCES FOR PROMOTING MORE PERFECT
COMBUSTION OF FUEL IN THE FURNACES OF STEAM BOILERS," to be as follows:-
The object of my invention is to economise fuel and minimise the production of smoke.
.I effect these objects in the following manner and although my invention is
applicable to various types of steam boilers a description of the same as applied to a
Cornish or one flued steam boiler will suffice.
In the furnace or flue tube of such a boiler I place a metallic air box or metallic
air boxes in the fire bridge, or I construct the fire bridge of fire brick or other
refractory material with air chambers, or a hollow bridge may be constructed partly
of metal and partly of refractory material such as fire brick.
Inside the Hue tube at the back of the fire bridge I place one or more metallic
pipes for conveying air from the back of the boiler; the inlet end of the pipe or pipes
being placed outside the flue, the other end of the same being connected with the air
box or boxes or chambers in the fire bridge of the furnace. Outlets, for the air
brought to the interior of the fire bridge through the last named pipes, are provided at
the back or the top or the front of the bridge or otherwise as may be found most
convenient.
By preference I place the air pipes last described at each side of the flue tube, in
line, or thereabouts with the centre of the furnace; in that position they are subjected
to the flame and heated gases passing from the furnace to the flue, and the air passing
through the interior of the pipe to the bridge is in consequence highly heated, and
emerges from the openings provided in the bridge in such a heated and rarefied con-
dition as to more readily amalgamate with the gases and other products generated in
the fire place, thereby contributing to more perfect combustion with the consequent
economy in fuel and reduction of smoke.
In some cases instead of the air pipe going direct from the back of the boiler
through the flue to the outer air, I connect it to a cross pipe or pipes by means of
which a larger amount of the waste heat from the flue of the boiler may be utilised for
heating the air passed through the pipes to the bridge. A connection or connections
being provided to such cross pipe or pipes to the outside of the flue.
In some cases where the natural draught is not sufficient to induce a current of air
through the pipe or pipes I employ a steam jet at the inlet end or ends of the pipe or
pipes or I force the air through the pipes by means of pressure from a blowing engine
or fan or by other suitable means.
I also where necessary provide a valve or damper by means of which the admission
of air through the bridge may be regulated.
As a modification in the construction of the fire bridge I make the lower part of the
bridge in the form of an air box entirely of cast iron and to the back of this portion of
the bridge I connect the air pipes previously referred to. The upper part of the
bridge 1 construct, of the necessary form, also in metal, so as to fit onto or into the
lower part of the air box, such upper part or lid being likewise inade hollow and pro-
vided with lips or flanges for the reception of the top or cover brick or bricks. In this
upper portion of the fire bridge or in the cover brick or bricks placed thereon I form
the holes or orifices by means of which the heated air from the air pipes and bridge is
passed into the furnace.
The lower part of my improved fire hridge may be provided with a dead plate or

page_text: bearer for carrying the back ends of the fire bars and for carrying the fire bricks for
protecting the front of the metallic air box or cover, such dead plate or bearer may
be either rivetted or cast on or otherwise attached to the said air box.
I am aware that there are many inventions for conducting and heating air through
the fire bridges of furnaces for the purposes herein described and 1 lay no claim to
novelty in this respect. The essential feature of my invention being the combination
of parts and appliances by means of which I conduct and heat a current or currents
of air from the back or rear end of a steam boiler to a hollow fire bridge such current
or currents of air being heated in its passage through a pipe or pipes partly in the
waste flue of the boiler, partly in the flue tube or furnace, and partly in the hollow fire
bridge in the manner and for the purposes herein set forth.
Dated this 15th day of November 1889.
R. HEBER RADFORD,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Apparatus and Appliances for Promoting More
Perfect Combustion of Fuel in the Furnaces of Steam Boilers.
I, JAMES MELLAR, of 34, Palmer Road, Darnall, near Sheffield, in the County of
York, Mechanical Engineer, do hereby declare the nature of my said invention for
"IMPROVEMENTS IN APPARATUS AND APPLIANCES FOR PROMOTING MORE PERFECT
COMBUSTION OF FUEL IN THE FURNACES OF STEAM BOILERS," and in what manner the
same is to be performed to be particularly described and ascertained in and by the
following statement :-
The object of my invention is to economise fuel and minimise the production
of smoke.
I effect these objects in the following manner and although my invention is
applicable to various types of steam boilers, a description of the same as applied to a
Cornish or one flued steam boiler will suffice.
In the furnace or flue tube of such a boiler I place a metallic air box or metallic
air boxes in the fire bridge, or I construct the fire bridge of fire brick or other
refractory material with air chambers, or a hollow bridge may be constructed partly
of metal and partly of refractory material, such as fire brick.
Inside the flue tube at the back of the fire bridge I place one or more metallic
pipes for conveying air from the back of the boiler, the inlet end of the pipe or pipes
being placed outside the flue, the other end of the same being connected with the air
box or boxes or chambers in the fire bridge of the furnace. Outlets for the air
brought to the interior of the fire bridge through the last named pipes, are provided at
the back, or the top, or the front of the bridge, or otherwise as may be found
most convenient.
By preference I place the air pipes, last described, at each side of the flue tube, in
line or thereabouts with the centre of the furnace in that position they are
subjected to the flame and heated gases passing from the furnace to the flue and
the air passing through the interior of the pipe to the bridge is in consequence
highly heated, and emerges from the openings provided in the bridge in such a
heated and rarified condition as to more readily amalgamate with the gases and other
products generated in the fire place, thereby contributing to more perfect combustion
with the consequent economy in fuel and reduction of smoke.
In some cases instead of the air pipe or pipes going direct from the back of the
boiler through the flue to the outer air, I connect it or them to a cross pipe or pipes
by means of which a larger amount of the waste heat from the flue of the boiler may
be utilised for heating the air passed through the pipes to the bridge. A connec-
tion or connectious being provided to such cross pipe or pipes to the outside of
the flue.
In some cases where the natural draught is not sufficient to induce a current of
air through the pipe or pipes I employ a steam jet at the inlet end or ends of the

page_text: pipe or pipes, or I force the air through the pipes by means of pressure.from a
blowing engine or fan or by other suitable means.
I also, where necessary, provide a valve or damper by means of which the
admission of air through the bridge may be regulated. As a modification in the
construction of the fire bridge I make the lower part of the bridge in the form of
an air box entirely of cast iron and to the back of this portion of the bridge
I connect the air pipes previously referred to. The upper part of the bridge I
construct of the necessary form, also in metal, so as to fit on to or into the lower
part of the air box such upper part or lid being likewise made hollow and provided
with lids or flanges for the reception of the top or cover brick or bricks. In this
upper portion of the fire bridge or in the cover brick or bricks placed thereon, I
form the holes or orifices by means of which the heated air froin the air pipes and
bridge is passed into the furnace.
The lower part of my improved fire bridge may be provided with a dead plate or
bearer for carrying the back ends of the fire bars and for carrying the fire bricks
for protecting the front of the metallic air box or cover, such dead plate or bearer
may be either rivetted or cast on or otherwise attached to the said air box.
I am aware that there are many inventions for conducting and heating air through
the fire bridges of furnaces for the purposes herein described and I lay no claim to
novelty in this respect, the essential feature of my invention being the combination
of parts and appliances by means of which I conduct and heat a current or currents
of air from the back or rear end of a steam boiler to a hollow fire bridge such
current or currents of air being heated in its passage through a pipe or pipes partly
in the external or waste flue of the boiler, partly in the flue tube or furnace, and
partly in the hollow fire bridge in the manner and for the purposes herein set
forth.
The object of my invention will be better understood on reference to the accom-
panying sheet of drawings in which,
Fig. 1. is a cross section of a Cornish or one flued steam boiler, such section being
taken through the fire bridge, on the line A. B.
Fig. 2. is a longitudinal section of the same taken through the centre of the flue,
on the line C. D.
Fig. 3. is a sectional plan of the same, taken through the line E. F.
The same letters refer to similar parts throughout the several views.
a, a, is the furnace or flue tube.
b, b, is the lower part of the metallic air box or air boxes,
bi, being the upper part of the same.
c, is the fire brick front of the fire bridge and,
c³, the fire brick top or cover of the same,
b, c, and forming a hollow bridge constructed partly of metal and partly of
refractory material.
d, d are the metallic air pipes for conveying air from the supply pipe or pipes g. 9,
or i, i, as the case may be to the metallic air box or air boxes b, b, below the fire
bridge b, c and c¹.
e, being one mode of arranging the inlet end of the supply pipe or pipes g,
leading to the same.
fff are outlets for heated air in the back of the hollow bridge, similar outlets may
likewise be provided in the top or front of the bridge or otherwise.
9, is an inlet pipe or pipes through which the air may be conveyed to the pipes d, d,
either direct or through the cross or branch pipe h, by natural or forced draught as
previously described,
i, being a similar inlet pipe or pipes which may be placed either in the main flue
between the boiler and the chimney stack, or in the external flue or flues either under
or at the sides of the steam boiler or both before they are connected to the cross or
branch pipe, h, or direct to the air pipes d, d.
The arrows indicate the direction of the currents of air from the supply pipes g, or i,
at the back of the boiler through the pipes d, d, into the air box or boxes b, b, and

page_text: hollow bridge ¹, and thence through the outlets f, f, into the furnace or flue
tube a, a.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed, i declare that what I
claim is ;
(1). In the furnaces or flue tubes and in the waste and external flues of steam
boilers the combination of parts and appliances comprising the pipes, fittings and
connections by means of which I conduct from the back or rear ends of such boilers
currents of air to one or more air boxes and hollow fire bridges and thence through
holes or orifices formed in the back or the top or the front of such bridges into each
of the furnaces or flue tubes of such steam boilers; such current or currents of air
being induced either by natural or forced draught and heated in passing through the
said pipes, fittings and connections partly in the waste flues or partly in the external
and waste flues and partly in the pipes and connections placed in the furnaces or flue
tubes and partly in the air boxes and hollow fire bridges of such boilers, substantially
as and for the purposes herein described and illustrated on the accompanying sheet of
drawings.
(2). Improvements in apparatus and appliances for promoting more perfect com-
bustion of fuel in the furnaces of steam boilers, substantially as and for the purposes
herein described and illustrated on the accompanying sheet of drawings.
Dated this 14th day or August 1050.
R. HEBER RADFORD,
Agent for the Applicant.
R. HEBER RADFORD,
Agent for the Applicant.