Improvements in Furnaces.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in Furnaces.
I, HOWARD MATRAVERS ASHLEY, of Ferrybridge, in the County of York,
Engineer and Ironfounder, do hereby declare the nature of this invention
to be as follows:-
-
In my Specification 16644% I describe an invention for improvements in fur-
nace bars and their frames and in the mode of fixing the same, also in the fire
bridges used in connection therewith and my present invention is an improve-
ment of this, especially in relation to the construction of the bridges, the elonga-
tion of the fluted blocks at the ends of the furnace bars and the means of regu-
lating or balancing the amount of air supplied to the front of the fire, so as to
agree with the amount of air that passes through the bars and through the said
bridges, and I carry out my invention in the following manner; -
Instead of chamfering or cutting away the blocks on the ends of the bars as
shewn in Figure 2 at a a in my specification above referred to, I now elongate
them so that the heated air shall have a longer distance to travel through the
hollows of the blocks before passing through the slots of the carrier bar C and
back plate B in the said specification.
I find, in practice, that the flue G in the double bridge shewn in the said speci-
fication, through being left open at the top, causes the flame to impinge irregu-
larly upon the crown plate immediately over it, thereby tending to damage the
plate. To obviate this I construct the bridge preferably of whole blocks instead
of loose firebricks so that the front bridge, or that nearest to the fire shall be
made with an arch all round its upper face, and wide enough to reach across
the flue between the two bridges, and also across the back bridge, and on the
under-side I provide two or more projections in such a position as to divide the
arch into three or more open divisions which allow the heated air that has passed
between the two bridges to pass out behind the back bridge in a direction parallel,
or nearly so with the tube in which the furnace is constructed. By this means
the flame coming over the front bridge mixes with the heated air after it has
passed over both bridges and produces combustion of the smoke without imping-
ing unduly upon any of the boiler plates.
I also make provision for the regulation of the air that is to be admitted to
the furnace by providing the ashes hole under the furnace with a door worked
upon a rack or other suitable provision, and also a valve in the firing door of the
furnace, which falls open each time the furnace is supplied with fuel, and is
closed by the stoker when the first smoke is burnt off. This valve is constructed
by fixing a frame to the usual firing door of the furnace and hinging to the
bottom edge of it another door which contains a hit-and-miss ventilator and a
balance weight at the top end. It is also provided with two horns at its lower
extremity in which are adjusting screws which are set to any position to allow
it to fall the required distance, by the action of the balance weight for the admis-
sion of air.

page_text: By means of the falling flap working on the rack to regulate the draught to
the ashes hole, and the falling valve attached to the firing door which regulates
the amount of air for the front of the furnace in combination with the bridges.
and bars as above described I am able to consume almost the whole of the smoke
that would otherwise be emitted from the chimney of the furnace, and also to
greatly economise the consumption of fuel.
Improvements in Furnaces.
I, HOWARD MATRAVERS ASHLEY, of Ferrybridge, in the County of York,
Engineer and Ironfounder, 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:-
In my Specification No. 16,644 of 1890, I describe improvements in furnace
bars and their frames and in the mode of fixing the same, also in the fire bridges
used in connection therewith, and my present invention relates to improvements
of this, especially in relation to the construction of the bridges, the elongations
of the fluted blocks at the ends of the furnace bars, and the means of regulating
or balancing the amount of air supplied to the front of the fire, so as to suit the
amount of air that passes through the bars, and through the bridges, I carry
out my invention as I shall describe referring to the accompanying drawings.
Fig. 1 is a part longitudinal section of the fire flue of a boiler with fire and
bearing bars and bridges arranged according to my invention.
Fig. 2 is a rear elevation of the bridge.
Fig. 3 is an elevation of the back bearing bar, Fig. 4 is an elevation, and Fig. 5
is a vertical section of the boiler front.
Instead of chamfering or cutting away the blocks on the ends of the bars as
shewn at a a of Fig. 2 of the drawings annexed to my Specification above referred
to, I now elongate them as shewn in Fig. 1 of the drawings accompanying the
present specification so that the heated air shall have a longer distance to travel
through the hollow of the blocks before passing through the slots of the bearing
bar I and back plate 6. I find in practice that by leaving open at the top the
flue G in the double bridge described in my previous specification the flame is
caused to impinge irregularly upon the crown plate immediately over it and
tends to damage the plate. To obviate this, I construct the bridge preferably
of whole blocks A and B instead of loose fire-bricks so that the front bridge A
or that nearest to the fire is made with an arch all round its upper face, wide
enough to reach across the flue between the two bridges, and also over the back
bridge B and I provide two or more partitions a dividing the arch opening into
three or more open parts so that the heated air that has passed between the two
bridges issues behind the back bridge in a direction parallel, or nearly so to the
boiler tube in which the furnace is situated. By this means the gases coming
over the front bridge A become mixed with the heated air after it has passed
along both bridges and thus is effected complete combustion of the smoke with-
out any flame impinging unduly upon any of the boiler plates.
I also make provision for the regulation of the air that to be admitted to
the furnace by providing the ash pit with a door G that can be held in any posi-
tion on a rack H. I also provide for the fire door a hit or miss ventilator valve

page_text: on a flap F which can be opened for a short time when the furnace is supplied
with fuel, and closed when the first smoke is burnt off. The flap is hinged to
a frame projecting from the fire door and has at its top a knob c which acts as
a tumbling weight. The flap has also two horns g at its lower edge having
adjusting screws which can be set so as to allow the flap to fall more or less open
for the admission of air.
By means of the flap G regulating the air admitted to the ash pit and the
valve on the fire door which regulates the amount of air admitted over the fire
and by the supply of heated air at the bridges to the combustion gases passing
over them, almost the whole of the smoke is consumed, and considerable economy
of fuel is effected.
Having now particularly described and ascertained the nature of this in-
vention and in what manner the same is to be performed, I declare that what
I claim is:
1. The construction of the bridges A and B substantially as described.
2. In combination with the fire door a flap F carrying a ventilator valve sub-
stantially as described.
3. The flap valve G for the ashpit with means of holding it in desired position,
substantially as described.