Improvements in or relating to Furnaces for Steam Boilers.
Year: 1898

page_text: Improvements in or relating to Furnaces for Steam Boilers.
We, GEORGE WATSON and FRANK LESLIE WATSON, of 21, Springfield Mount, in
the City of Leeds, Engineers, do hereby declare the nature of this invention to be
as follows:-
:-
Our invention relates to furnaces for steam boilers in which combustion is pro-
noted or assisted by means of currents of air impelled by steam jet blowers, and
has for its object the more efficient combustion of fuel and the diminuition of
smoke, and as a means thereto to provide a method of heating such air before
it comes into contact with the fuel or partially burned gases by means of the
heat given off by the furnace gases.
We carry out our object principally by using a closed ashpit and forcing the
main supply of air into the ashpit by means of a steam jet blower or blowers placed
at or near the back end of the boiler and delivering air and steam mixed into
a tube or tubes formed preferably of cast iron and placed in one or more of the
flues by which the products of combustion are carried away from the furnaces.
This system besides providing a means of heating the main air supply has
amongst others the following advantages in comparison with the well known
method of placing the steam jet blower beneath the grate bars, for instance it
causes a more equal distribution of air to the different parts of the furnace, and
there is less inconvenience from the noise of the escaping steam.
The tube or tubes may discharge the heated air or steam into either the front
or back end of the ashpit. The discharge is through the bridge if the inlet open-
ing is at the back end of the furnace and through the front plate if it is at the
front end of the furnace.
For cases in which it is deemed advisable to provide a secondary air supply in
order to complete the combustion of the furnace gases, we provide a hollow metal
front to the furnace, above and at the sides of the firing door, and by means of a
steam jet blower we draw or force the secondary supply of air through the afore-
said hollow metal front, thereby heating it, and deliver it into the furnace above
the grate bars in such a manner as to cause such air to mix with the furnace gases.
The hollow front may be conveniently formed of ordinary front plates with box
baffles attached to them on the inside.
In addition to heating the secondary supply of air this arrangement has also
the advantage that it prevents the hollow metal front from becoming excessively
hot and thereby preserves it to some extent from damage by the action of the
fire.
As applied to Lancashire boilers when not provided with cross tubes or other
obstructions which would make it difficult to carry our air tube or tubes through
such flues, we pass our air tube or tubes along the bottom of each of the internal

page_text: boiler flues and through the fire-bridges into the ashpits, the air pipes being just
long enough to pass through the bridges and not projecting far under the grates.
As applied to a Lancashire boiler having cross tubes or other obstructions in the
internal flues as well as in all other cases wherein it is impracticable to carry our
air tube or tubes through the internal flues, we lay them instead along the external
flues, either the side flues or the bottom flue, as may be convenient.
000
1
1000
THOS. DALTON,
Solicitor, 65, Albion Street, Leeds,
Agent for the Applicants.
Improvements in or relating to Furnaces for Steam Boilers.
We, GEORGE WATSON and FRANK LESLIE WATSON, of 21, Springfield Mount, in
the City of Leeds, Engineers, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
Our invention relates to furnaces for steam boilers in which combustion is pro-
moted or assisted by means of currents of air impelled by steam jet blowers and
has for its object the more efficient combustion of fuel and the diminution of
smoke and, as a means thereto, to provide a method of heating by means of
furnace gases, such air before it comes into contact with the fuel or partially
burned gases.
First and principally we carry out our object by using a closed ash pit and
forcing the air required for combustion (hereinafter called the main air supply)
into the ash pit by means of a steam jet blower or blowers placed at or near the
back end of the boiler through a tube or tubes formed preferably of cast iron
and placed in one or more of the flues by which the products of combustion are
carried away from the furnaces.
This system besides providing a means of heating the main air supply has
amongst others the following advantages in comparison with the well known
method of placing the steam jet blower beneath the grate bars, namely, it causes a
more equal distribution of air to the different parts of the furnace and there is
less inconvenience from the noise of the escaping steam.
The tube or tubes may discharge the heated air or steam into either the front
or back end of the ashpit. The discharge is through the bridge if the inlet open-
ing is at the back end of the furnace, and through the front plate if it is at the
front end of the furnace.
Secondly and for those cases in which it is deemed advisable to make use of a
secondary air supply in order to complete the combustion of the furnace gases we
carry out our object by providing a hollow metal front to the furnace above and
at the sides of the firing door, and by means of a steam jet blower we draw or force
the secondary supply of air through the aforesaid hollow metal front, thereby
heating it, and deliver it into the furnace above the grate bars in such a manner as
to cause such air to mix with the furnace gases.
The hollow front inay be conveniently formed of ordinary front plates with box
baffles attached to them on the inside.
In addition to heating the secondary supply of air, this arrangement has also
the advantage that it prevents the hollow metal front from becoming excessively

page_text: hot and thereby preserves it to some extent from damage by the action of the
fire.
As applied to Lancashire boilers when not provided with cross tubes or other
obstructions so placed as to make it difficult to carry an air tube or tubes through
such flues we pass our air tube or tubes along each of the internal boiler flues and
through the fire bridges into the ashpits; the tubes being long enough to pass
through the bridges and not project far under the grates.
As applied to a Lancashire boiler having cross tubes or other obstructions in
the internal flues as well as in all other cases wherein it is impracticable to carry
our air tube or tubes through the internal flues, we lay them instead along the
external flues, either the side flues or the bottom flue, as may be convenient.
To enable our invention to be fully understood and readily carried into effect
we further refer to the accompanying drawings.
Fig. 1 is a front elevation of a Lancashire boiler fitted with our invention.
Fig. 2 is a longitudinal sectional elevation of the same.
a is a plate closing the front of the ashpit. a¹ are cleaning doors of any suitable
shape fitted in front of the ashpit. b, bare portions of the boiler shown broken
in length and c, c are the flues thereof. d, d are the firing doors. e is the dead
plate in front of the doors and f represents the grate bars. is the bridge. h, hare
the induction pipes or trumpets of steam jet blowers at the back of the boiler and
h¹, h are the horizontal tubes forming a continuation thereof conveying the
mixed air and steam therefrom to the outlet j in front of the bridge, & is a steam
pipe attached to the boiler through which steam is supplied to the blowers. I is
a stop cock. m is a continuation steam pipe therefrom with branches m', m³,
descending into the induction pipes h, h. n, n are branches from the steam pipe k
for the purpose of supplying steam to the secondary blowers in front of the furnace.
o, o are stop cocks, represents the hollow metal front of the furnace above and
around the firing doors and p³, 2 are holes in the front plate to admit air to the
hollow space. The steam pipes n, n terminate in nozzles q (preferably adjustable
as shown) in front of trumpets r of the secondary blowers secured to the inner face
of the hollow metal fronts p.
Fig. 3 is a front elevation and Fig. 4 a longitudinal section of a boiler on its
seat for the purpose of showing the application of our apparatus in the case of
the boiler being fitted with cross tubes or other obstruction.
In this case the horizontal tubes h¹, h¹ are laid in the side flues s, s external
to the boiler and are continued from back to front and are then turned upward
and enter the front plates at t, t. All other parts remain the same as in Figs.
and 2 herein before described. The method described in Figs. 3 and 4 is also
applicable with the necessary and obvious modification to every description of
boiler.
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;
1. The heating of the air required for combustion in the furnace of a steam
boiler by causing the same to pass through tubes laid in the flues (internal or
external) of such boiler substantially as herein before and in the drawings described.
2. The method of supplying heated air into the closed ashpit of a steam boiler
furnace through the bridge by means of tubes laid in the flues and of steam jet
blowers for the purpose and substantially as hereinbefore. and in the drawings
described.
3. The method of supplying heated air into the closed ashpit of a steam boiler
furnace through the front of such ash-pit by means of tubes laid in the flues and
of steam jet blowers for the purpose and substantially as herein before and in the
drawings described.
4. The method of heating air supplied by steam jet apparatus into the combus-
tion chamber of a steam boiler furnace above the level of the grate bars by passing

page_text: such air through a hollow metal front substantially as and for the purpose herein-
before described.
5. Apparatus substantially as represented by the annexed drawings for the
purpose of supplying heated air to the-furnaces of steam boilers.
Dated this 9th day of March 1899
THOS. DALTON,
Solicitor, 65, Albion Street, Leeds,
Agent for the Applicants.
THOS. DALTON,
Solicitor, 65, Albion Street, Leeds,
Agent for the Applicants.