IMPROVEMENTS IN BOILERS AND BOILER. FURNACES
Year: 1866

page_text: PROVISIONAL SPECIFICATION left by Henry Fisher at the Office of
the Commissioners of Patents, with his Petition, on the 3rd October.
1866.
I, HENRY FISHER, of Kenyon Terrace, Devonshire Road, Claughton, near
Birkenhead, in the County of Chester, Civil Engineer, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN BOILERS AND BOILER.
FURNACES," to be as follows (that is to say) :-
The object of this Invention is to obtain a more perfect combustion of the
gases distilled from the fuel than is now done in ordinary furnaces.
In applying this Invention to say, an oblong boiler, in which the furnace door
or mouth is at one end, the construction is as follows:-The platform on which
the fuel rests may be of any suitable construction; the bridge or check piece
at the back of the furnace or fuel chamber may be of brick, or a water space
opening into the sides of the boiler; this check piece is carried up from the
fuel platform to the top of the fuel chamber, there being formed through it
one or more openings for the admission of air to the solid fuel on the platform,
and which air passages are connected with an air chamber formed between
the check piece and a water space about the height of the fuel chamber, and
in the rear of the check piece, and the said air chamber is continued to and
into the ash-pit, or elsewhere. The top or crown of the fuel chamber is a

page_text: brick arch, tiles, or horizontal or arched water space opening into the sides of
the boiler, and generally lined with brick as named herein-after, and extends
from the top of the transverse wall or check piece at the back of the furnace
to a given distance over the fuel bed, say, about two-thirds the distance over
the fuel, so as to leave between the said arch and the projection herein-after
named as being formed over the mouth, a sufficient space or up-take at the
door end to allow the gases to pass out of the fuel chamber upwards into the
gas chamber, which is formed immediately over the arch over the fuel chamber,
and between the top of the said arch and the water space at the top of the
boiler; the gases are then conveyed into a chamber at the rear of the water
space above described, as forming one side of the air chamber at the back of
the furnace, and thence forward in any required course. Where no ash-pit
is used, the air chamber at the back of the bridge or check piece opens out
below, or at the side of the boiler, and is supplied with air through a suitable
passage. The air passages formed through the check piece at the back as
herein-before described, and immediately entering the fuel chamber, are made
about two or three times longer than they are in height, and the opposite sides
are parallel to each other, and the upper and lower sides being inclined to
the horizon, whereby the air in passing through them will acquire a direction
which it will maintain until it reaches the fuel, without scarcely combining at
all with the surrounding gases, whereas were a deflector used of the ordinary
kind, namely, an inclined plate for the air to strike against, or a bent tube or
orifice whose height is about equal to or greater than the depth, the air
would be diffused in the fuel chamber, and combine too much with the gases
instead of falling wholly or nearly so on to the fuel. Through or over the
door there are formed air passages which enter the fuel chamber, similar to
those described in the check piece and for a similar purpose, and are set
therefore at an opposite angle to the back openings. In order to complete
the combustion of the gases after they leave the fuel chamber, and imme-
diately on their passing the up-take into the gas chamber, the gases are supplied
with air from air passages made through the front of the boiler, (or through
the brickwork above the door), and nearly in line with or a little higher than
the top of the arch or platform over the fuel chamber forming the bed or floor
of the gas chamber, and which air passages open into the gas chamber either
in an horizontal or inclined position. In all possible cases of admitting air to
the gases after they have passed over the bridge at the back of the fuel
chamber as is now done, the gases tend npwards from and above the air
orifices, and the air by its superior specific gravity tending downwards, there-
fore perfect combustion cannot take place. Carbonic oxide may be formed,

page_text: and thus render the gases invisible as they pass from the chimney, but
perfect combustion can only be formed to a small extent, and conse-
quently a great loss of heat is sustained; whereas by lighting the gases as
proposed in the front or door end, after they pass through the up-take into
the gas chamber from out of the fuel chamber a cold stream of air has only
to penetrate a constant sheet of flame, the thickness of such opening or up-take
between the two chambers, and as the flame by its inferior gravity with
relation to the stream of air must cross the latter, as it is evident that a more
perfect combustion will take place than in the present plan adopted at the
bridge, assisted by air over or through the door. In some cases in place
of forming the furnace door at the end of the boiler, it is preferred to
construct it on one side of the boiler, at or near the middle of the fuel plat-
form, and in which latter arrangement the air is admitted at one end through
the check piece as herein-before described, and again is admitted through an
opening or openings at one side of the furnace door, and immediately opposite
to the up-take between the fuel and gas chambers, and at a line a little above
the brick arch or water space described, as being over the fuel chamber.
Sometimes the gas chamber herein-before described over the fuel chamber is
dispensed with, in which case the gas in the fuel chamber is then brought
near to the front, and then returned through a gas chamber or chambers on
one or both sides of the furnace chamber or boiler on the same level, or
nearly so, as the fuel chamber, and continued to the back of the furnace
or boiler according as the lateral gas chamber or chambers are carried inside
or outside the boiler..
It will be seen from the foregoing that in case of, say, an ordinary oblong
boiler in which the furnace extends from the front to the bridge at the
back, that instead of having the outlet situated over the bridge for the escape
of the gases from the furnace according to this Invention, the outlet or up-take
for the gases from the furnace is formed in an horizontal position or nearly so,
and in line with the crown or top of the fuel chamber, so that when this outlet
or up-take is situated towards the door end of the furnace the gases on or
immediately after leaving the furnace are ignited in the gas chamber by a
stream of air, which has only to pass through-the thickness of the boiler water
space, say, through about six inches, instead of passing through long and
heated chambers, as heretofore, and the gases are then returned over a flue
or gas chamber extending from the front water space of the boiler over the
whole length of the crown or top of the furnace, and between the crown of
the furnace and the top water space of the boiler, whence the gases are con-
veyed downwards in the rear of the furnace and of the back air chamber. The

page_text: top of the door or mouth generally projects into the fuel chamber a short distance,
say a few inches; according to the length of the furnace. The air passages
described as formed through the check piece at the back of the furnace or fuel
chamber are sometimes dispensed with, and in such case any air that may be
required in the fuel chamber in addition to that supplied through the fuel
platform is supplied through the air passages described as as being over or
through the door and opening into the fuel chamber. Sometimes in place of
having the outlet or up-take for the gases from the fuel chamber into the
gas chamber formed at or near the door or front of the boiler, as before
described, it is preferred to have the said outlet or up-take at or near the back
of the fuel chamber, in which latter arrangement the brick arch or water space
over the fuel bed extends from the front of the boiler towards the above
described check piece a given distance, say, about two-thirds the distance over
the fuel, so as to leave between the said arch and the said check piece a suffi-
cient space or outlet for the gases to pass out of the fuel chamber into the gas
chamber before mentioned, and thence towards and up to the front water space
of the boiler, where the gases are again ignited in manner as herein-before
described, and the gases are thence conveyed through tubes formed in the top
water space of the boiler; and when the said outlet for the gases from the
fuel chamber to the gas chamber is situated, as last described, the check piece
at the back of the boiler, and also the air chamber in the rear thereof, are
carried up from the fuel platform to the under side of the water space at the
top of the boiler, and generally has a short projection towards and about in
line with the arch over the fuel chamber, and above which projection air
passages are formed through the check piece opening into the said gas
chamber.
When a water space is substituted for brickwork in either or both, the
check piece and or the platform of the gas chamber, which is also the top
of the fuel chamber, they may be connected by tubes or a feather with the
water space at the top of the boiler. The side water spaces of the boiler
against which the brick arch over the fuel chamber presses may be strength-
ened by light girders or double angle iron placed in a vertical position and
rivetted to each side of the water space.
When the arch over the fuel chamber is constructed of brick, in consequence
of the flame passing over both its lower and upper surfaces, it always retains
and reflects such a degree of heat as will greatly assist the distillation of the
fuel, and also the ignition of the gases on charging the fresh fuel in com-
bination with the air admitted, as herein-before described. *
When the arch over the fuel chamber is a water space it is generally

page_text: preferred to cover the upper or lower or both surfaces thereof with a layer or
ring of bricks, or both, for the purpose of assisting the combustion of the gases
in the fuel or gas chamber, or both, in combination with the air admitted
into each respectively, as herein-before described, and the ring of bricks on the
under side of said water space may be supported by the side water spaces of
the boiler alone, or on brick pillars from the fuel platform.