IMPROVEMENTS IN FURNACES FOR STEAM BOILERS AND OTHER PURPOSES
Year: 1872

page_text: PROVISIONAL SPECIFICATION left by William Campbell at the Office
of the Commissioners of Patents, with his Petition, on the 2nd
October 1872.
I, WILLIAM CAMPBELL, of No 29, Ashfield Terrace West, New-
castle-upon-Tyne, Civil Engineer, do hereby declare, the nature of the
said Invention for "IMPROVEMENTS IN FURNACES FOR STEAM BOILERS AND
OTHER PURPOSES," to be as follows:—
The object of this Invention is to construct steam boiler and other
furnaces in such a manner that the coal is heated before it passes on
to the fire-grate, and the gases given off from the coal whilst being
thus heated perfectly consumed. For this purpose I construct furnaces
for heating steam boilers and other furnaces in such a manner that
the coal to be burnt is fed into the furnace at one end from a hopper
on to a plate inclining downwards towards the opposite end of the
furnace, where the ordinary grate bars are placed. The furnace is
constructed so that the draught shall pass from the grate bars to the
hopper end of the furnace, whereby the coals as they are from time
to time moved forward along the inclined plate become heated by
"

page_text: the heated gases from the fire on the grate bars, and in order that
the gases so driven off from the coal may be consumed I make provision
for admitting to these gases a sufficient admixture of air; this I do by
preference by dividing the plate into four or other number of steps one
below the other, so that the coal as it is moved towards the grato bars
drops from one step to the other, and the spaces between the steps
form openings for admission of air. I also divide the steps with
longitudinal slits, up through which air will also pass to the burning
gases; along the edge of the slits I form the plates with flanges
standing up from them to serve as guides for the tools by which the
coals are pushed down from one step to the other. By this means the
coal can be kept evenly spread upon the inclined steps during the
time it is being heated, and thereby coked. The coal hopper is open
at the bottom, excepting a bridge in the middle, so that the coals
within it rest upon the uppermost step, and at the back of the furnace
is a stoking hole through which a tool can be introduced to push the
coal towards the fire grate. The hopper at its upper end can be closed
by an air-tight cover, and the side of the hopper in the furnace may
be formed of grating to allow the draught to heat the coal as it is
cntering the flucs.
In place of the flame bed being made in steps as above described,
it may be of level brickwork, and there may be openings in the brick-
work sides of the furnace to admit air upou the flame bed to consume
the gases given off from the coal upon it. I however prefer to make
the flame bed of flat plates of cast iron, placed so that there shall be
a drop from one to the other, so that air may be admitted at the
drops.
Pokers are to be introduced into the furnace at the drops, and thero
is a trough cast across the end of the lowest plate at each drop to
catch coal; the coal can be pushed into the drops by a raker so as to
diminish the draught after coals have been stoked. The coal after
being thus pushed along the flame bed can be drawn off the end of
such bed on to the grate bars by a rake introduced through the
front door, and the ashes driven down into the ash-pit which is
underneath.
An ordinary cylindrical boiler may be set above, and so.form the
roof of a furnace arranged as above described, and the draught as it

page_text: leaves the hopper end of the furnace may be conducted by flues along
the sides of the boiler, or if the boiler is made with internal flues then
the draught may be conducted from the hopper end of the furnace
through these flues. Or the furnace itself might be within the tube
or flue of an ordinary Cornish boiler, in which case the hopper would
be at one end and the grate at the opposite end, the draught being
made to leave the furnace at the end where the coal hopper is placed.
When the furnace cannot be stoked from both ends, then the coal
hoppers in place of being at one end of the furnace may be placed
at the two sides of the furnace or introduced through the boiler into
the furnace, and the coking plates he then shortened.