Improvements in Steam Boiler and such like Furnaces.
Year: 1898

page_text: Improvements in Steam Boiler and such like Furnaces.
I, ROBERT BAIRD, Engineer, 12, Percy Street, Paisley Road West, Glasgow, do
hereby declare the nature of this invention to be as follows:-
My invention relates to the better consumption of fuel in furnaces such as are
placed in the flues of marine, Lancashire and Cornish boilers, also in other
furnaces built in horizontal flues.
I accomplish this by constructing a chamber over a portion of the fire bars at
the back end of the furnace. This chamber is preferably in the form of an arch
composed of fire brick or other suitable material, and open to the firing end but
enclosed at the back, and extending to a convenient height above the fire grate
to admit of being charged with fuel and otherwise attended to; leaving sufficient
room for the draught to pass between the roof of the arch and the crown of the
furnace.
My improvements are effected by the gases from under the arch being baffled
and retarded by meeting the more direct draught from the front and uncovered
portion of the fire, whereby they are greatly heated by their proximity to the live
coal and hot brick work, so that when they mingle with the colder gases from the
front they light up and consume particles of carbon that would otherwise go to
the chimney in the form of black smoke.
Another advantage is gained by the inrushes of cold air at the back and more
inaccessible part of the furnace being brought to a useful heat by passing under
and over the heated brickwork of the chamber and making the combustion more
complete than it otherwise would be.
In this chamber I may leave openings at the back or sides by which a small
portion of the hotter gases may pass and join the main body of the draught.
This may be for the purpose of further promoting combustion or increasing the
area by which the gases are admitted to the flues.
Dated this 28th der of February 1808

page_text: performed, to be particularly described and ascertained in and by the following
statement:-
-
My invention relates to the better consumption of fuel in steam boiler and other
furnaces, such as are placed in horizontal flues where the draught leads in a
direction parallel with and over the fire grate, as in types of marine, Lancashire,
and multitubular boilers, also in flues for heating and drying purposes, and does
not relate to furnaces in which the gases are drawn in a vertical direction from
the fuel, as in types of deep fire-box boilers.
I obtain a better and more complete consumption of the light carbons and com-
bustible gases that are drawn from the fuel by causing them to pass through and
over a chamber which I construct at the back end of the fire grate.
Preferably I make this chamber by forming an arch of fire-brick over a portion
of the back end of the fire bars, or it may extend over a brick or iron bottom
which would be an extension of the line of firegrate surface, and open to the front
so as to be accessible for the supply of fuel or for cleaning purposes.
Between the crown of the furnace and the top of this arch, I leave a space large
enough to allow the main body of the gases to pass, but under the arch I retard
the gases by partly closing the back end of the chamber. The great heat from the
burning fuel and hot brick work of the chamber raises the temperature of the
gases passing through the chamber, far above the temperature of the gases that
have given off a part of their heat to the steam producing or heat absorbing
surface of the flue, so that when the hotter and colder gases mix, a renewed and
better combustion takes place.
Besides leaving an opening for the gases to pass from the chamber at the back
end, I leave openings in the arch which forms the roof of the chamber, whereby
they may pass through and mix with the colder gases passing between the roof of
the chamber and the flue.
In order to somewhat reduce the extreme heat of the fire bricks forming the
roof of the chamber, I make provision for admitting a supply of cold air which
enters the chamber and mixes with the gases, thus also supplying elements
required for their more complete combustion, and re-igniting exhausted particles
that would otherwise go as deposit or black smoke.
So that my invention may be more clearly understood, I will now describe it
with reference to the accompanying drawings, which illustrate it as applied to the
horizontal flue of a steam boiler.
Fig. 1, is a longitudinal section at b, b, Fig. 2, of part of a boiler flue in which
my invention is shown, built at the end of a grate on which fuel is burned for
steam raising or heating purposes.
Fig. 2 shows a cross section at a, a, Fig. 1.
The same letters of reference indicate corresponding parts in Figs. 1 and 2.
The lines on each side of K, Fig. 1, cover the extent of the fuel burning or grate
surface.
F, Fig. 1, is the fire door and what is referred to as the front of the furnace,
through which the fuel is passed and cleaning effected.
E, E, Fig. 1 are the fire bars between which air is admitted to the fuel.
1, Fig. 1 is section of front dead plate which is also a bearer for one end of
the front set of fire bars.
2, Fig. 1 is section of back dead plate, the front side of which bears one end
of the back set of fire bars. At the back of this dead plate and between the brick
work M is an opening, H, Fig. 1, preferably of from one half inch to one inch
wide, and extending across the section to the extent of the lines on each side of H,
Fig. 2, by which air is admitted from the ash pit. This air passes into the
chamber shown in longitudinal section C 1, C 1, Fig. 1 and cross section C 1,
Fig. 2, and has for its object the modifying of the heat of the fire bricks C, C,
Fig. 1, and C, C, C, Fig. 2, and also that of promoting the combustion of the gases
at the point where they leave the furnace and pass to the flues.

page_text: P, Fig. 1, shows a space between the fire bricks C, C, which allows a portion of
the gases from the chamber to mix with the gases passing from the furnace to
the flues by the opening O.
M, Figs. 1 and 2, is section showing brick work, part of which forms bottom
and back wall of chamber.
0, Figs. 1 and 2, shows the space by which part of the gases from the furnace
passes between the flue and the top of the arch, to the chimney, the other space
being under the arch at N, Figs. 1 and 2.
I, Fig. 1, shows the centre bearer for one of the ends of the front and back
rows of fire bars.
E, E, Fig. 2, shows the cross section of fire bars.
The lines on each side of L, Fig. 1 show length of ash pit.
L, Fig. 2 shows cross section of ash pit extending upwards to fire bars E, E.
C, Figs. 1 and 2 shows fire bricks forming roof of chamber. The bottom of
this chamber may be made hollow instead of being solid brickwork as shown, and
the bottom of said chamber may he composed entirely of bars with air spaces
between, or a perforated plate of any suitable material may be used. The
chamber may be quite closed all round except the front, when any gas generated
therein from burning fuel, would have to return and pass by the space marked
0, Figs. 1 and 2.
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
Better and more complete combustion of fuel and combustible matter arising
therefrom, in steam boiler and such like furnaces, by constructing a chamber at
the back end of such furnaces, in which fuel may be burned and gases reheated
so as to consume combustible particles or inflamable gases, that might otherwise
form deposit in the flues, or go out at the chimney as black smoke, substantially
as described and illustrated.
000