IMPROVEMENTS IN FURNACES
Year: 1869

page_text: PROVISIONAL SPECIFICATION left by Thomas Joseph Leigh at the
Office of the Commissioners of Patents, with his Petition, on the
17th August 1869.
I, THOMAS JOSEPH LEIGH, of 24, Mostyn Road, Brixton, in the
County of Surrey, Civil Engineer, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN FURNACES," to be as follows:-
In the Specification of a Patent, bearing date the 12th June 1866,
No. 1594, granted to me for "Improvements in the Method of Burning
Coals, (whether Large or Small Coals), Coal Dust, Coke, Coke Dust,
Charcoal, Wood, and other.Combustible Substances, as also Hydrocarbons.
and Gases, and in the Arrangement of the Furnaces applicable thereto;"
also in the Specification of another Patent, bearing date the 5th December
1867, No. 3468, granted to me for "Improvements in Furnaces, and in
Effecting the Combustion of Fuel therein," I described furnaces
constructed according to my Invention having a fixed bottom to the
combustion chamber or gas generator, charged with a stratum of molten
matter which formed a liquid bed for the fuel. As I find that furnaces
of construction similar to those described in the said Specification can
operate without a liquid bed for the fuel, and as I find it convenient to.
.1

page_text: get access for cleansing or repair to the bottom of the chamber or
generator, one of my present improvements is so to construct the
bottoms of such furnaces that they can be readily opened and closed.
For this purpose tliey may be formed of metal plates or castings, coated
by preference with loam, clay, or other refractory material, one or more
of these plates or castings being fixed, and the others being hinged
thereto, so that they can be opened like doors for giving access to the
chamber.
In the Specifications above referred to I also described modes of feeding
or delivering fuel into the chamber or gas generator, my present Invention
applies to improved apparatus. For this purpose I arrange one or more
pairs of helically grooved or fluted rollers or cylinders in a box at the
base of the fuel hopper in a horizontal position. The two rollers of each
pair are placed side by side and are caused to revolve in opposite
.directions, motion being imparted to them from a shaft mounted across
their front ends by mitre or bevil gearing, or by means of right and left
worms on the shaft working into screw wheels on the axes of the rollers,
the shaft being turned by hand or any convenient power. The helical
flutes or grooves in the cylinders are by preference made to decrease in
depth from the end in the hopper or the feed end which receives the fuel
to the discharge end, or end from which it is delivered into the furnace.
Thus the fuel is reduced to pieces small and nearly uniform in size before
its delivery, and the power of the helices to propel the fuel and to
overcome the resistance and friction which may result from its coking
is increased. The portions of the helically grooved rollers which pass
through the sides of the furnace work in tubes or chambers which may
have internal helical grooves or ribs to assist in the crushing and delivery
of the fuel. The tubes or chambers in which the grooved rollers work
are by preference placed in a cold air chamber supplied from a fan or
other blowing apparatus. The air passing through this chamber and
thus keeping the feed apparatus cool is led to the tuyere box and into the
furnace. By arranging its outlets around or over the discharge ends of
the rollers these ends are kept cool and the fuel is prevented from
coking. Water might be introduced into the chambers around the rollers
instead of air, and supplied in a continuous stream for the purpose of
cooling. The area or depth of the helical grooves may be made to
diminish gradually from the feeding end to the discharge end by tapering
the rollers and mounting them with their axes inclined to one another
in tubes or chambers made to suit their forms and positions. The helically

page_text: fluted rollers are so adjusted that the edges of their helical ribs overlap
each other, and this most where the grooves are deepest, the effect being
to break up and press forward the fuel. Instead of the pairs of helically
grooved rollers I sometimes mount at the bottom of the fuel hopper a
spindle or a series of equidistant spindles which are kept cool and
caused to rotate in a manner similar to that described with reference to.
the grooved rollers. On these spindles I fix a series of propellers which
are sections of a screw or a series of knives, cutters, or blades arranged.
in a helical form. The spindles may be made to revolve in the same
direction and not in opposite directions as in the case of the pairs of
grooved rollers. At their discharge ends it is desirable to fix a few
counter blades in the tubes or chambers in which they work, such
counter blades alternating with sections of the screws on the spindles
or with some of the blades thereon. These fixed blades acting in
conjunction with the rotating blades serve to break up the fuel and
prevent it from coking and sticking at the discharge end. I sometimes
use complete screws for part of the length of each spindle near the
feeding end or base of the hopper, and near the discharge end I cut
away portions of the screws to clear the counter blades; or complete
screws may be used for the whole length, the discharge ends being
protected by an air box and delivering on an inclined plane, as described
in the Specifications of the Patents above referred to. The screw may
taper, the discharging end being the smaller, and in this case the pitch
of the screw is made to increase towards the smaller end. In all the
foregoing arrangements the tubes and chambers in which the propellers
or fluted rollers work are by preference placed in a horizontal position,
but they may be more or less inclined. Instead of one or more screws
or fluted rollers applied as above described, I sometimes mount a single
transverse shaft along the base of the hopper and cause it to rotate.
This shaft carries a series of knives, cutters, propellers, or cams, by
preference arranged helically so as to secure a more regular and continuous
feed. The knives or cams are fixed on the shaft at intervals, and at the
back of the hopper is fixed a comb or a series of knives, cutters, or blades,
projecting into the spaces between the knives on the shaft. This comb
serves to free the fuel from the rotating shaft, and to cause it to fall
through a longitudinal opening into the furnace, or by preference on an
inclined plate arranged with a cold air box and blast as I have formerly
described. The fuel falling on to the inclined plate is projected thence

page_text: into the furnace, its fall being assisted by the blast from the cold air
chamber which passes over the plate and keeps. it cool.
The several modes of feeding fuel herein described may be used in
conjunction with any of the various forms of gas furnaces, step grates
or step rosts, or inclined grates, as well as with the furnaces or gas
generators described in the Specifications of the Patents already referred
to, and may generally be applied to all furnaces.