IMPROVEMENTS IN FURNACES
Year: 1863

page_text: PROVISIONAL SPECIFICATION. left by John Hendry and William Coutts
at the Office of the Commissioners of Patents, with their Petition, on
the 4th September 1863..
We, JOHN HENDRY and WILLIAM COUTTS, both of the City and County of
Aberdeen, North Britain, Merchants, do hereby declare the nature of the said
Invention of "IMPROVEMENTS IN FURNACES," to be as follows,- that is to say :-
This Invention consists in new.and improved modes of constructing furnaces
for the more perfect combustion of coal, wood, and other fuels, and of their
gaseous products, to the extinction of all visible smoke and perfect utilization
of all the heat producible from such fuel.
Under one modification of these improvements, as applied to an ordinary
horizontal cylindrical steam boiler with an internal flue through the centre,
the furnace is constructed of a deep vertical rectangular tunnel shape; arched
over the top, and by preference for a boiler of the smaller class formed at the
front end in the brickwork. This tunnel-shaped furnace is formed by pre-
ference nearly in horizontal section at the top, tapering out wide as it descends
in its transverse section to the full width of the flue running underneath the
boiler, which it enters by an aperture or throat at the bottom on a level with
it. At the front end of the furnace three apertures are formed, the large one
at the top being the furnace mouth through which the furnace is filled up to ȧ
level with it, and having doors to regulate a supply of air through them, the
other two being narrow apertures: the full width of the furnace, which admit
of the fuel being stirred from without, the one near the bottom -being alsc

page_text: used for pushing forward the fuel where it is in the most perfect state of
combustion, and the other higher up or a little below the furnace door where
the fresh coals begin to ignite and cake into lumps. These apertures are also
formed with doors for the regulation and admission of air to the furnace, the
gases passing down from the fresh fuel through the hottest part of the fire to
the throat where they are ignited and consumed. But the greatest amount
of air is required where the gases are.formed and escape at a high temperature
from the incandescent fuel at the throat of the furnace where the flame runs
beneath the boiler, so that for the necessary supply of air at this part a
transverse duct or channel runs across near the throat, and by preference
above it, opening downwards through a narrow slit, and meeting the gases as
they escape from the face of the incandescent fuel, so as to ignite with them
and cause perfect combustion of all the ignitable products. The air is
supplied to this cross channel by two flues or ducts at both ends, running
along the sides of the furnace or of its hot flues, so as to heat the air on its
way from their mouths which open to the atmosphere at the front or sides of
the brickwork, and furnished also with doors for regulating the amount of air
required, that being easily seen through sight holes for watching the state of
combustion at the throat and lower part of the furnace, the flame and
heated gases acting on the bottom of the boiler as they pass to the back end,
where they ascend and return through the central flue of the boiler to a
channel over the throat and main air channel, from which they finally pass
off by the side flues round the boiler to the chimney. This furnace is much
simpler and cheaper in construction than those at present in use, it has no
furnace bars or ash-pit, the coals gradually falling down by their own
gravitation to the bottom or hottest part of the furnace, where the solid
matters or refuse are reduced to fine dust without clinkers, which flies off with
the draught, while all the combustible gases are ignited with the air at their
proper temperatures, so that no visible or black smoke passes off at the chimney,
and the greatest possible amount of heat is produced from the fuel consumed.
Many modifications of this system of constructing furnaces to suit particular
purposes may be adopted, but the one herein specified shows the distinguishing
features of this Invention, which is peculiarly applicable to all kinds of
furnaces for steam boilers for the prevention of smoke combined with great
economy in the combustion of fuel.