Improvements in Furnaces and Furnace Feeding Apparatus for Utilizing Small Coal and the like as Fuel.
Year: 1895

page_text: Date of Application, 14th Sept., 1895-Accepted, 19th Oct., 1895
COMPLETE SPECIFICATION.
Improvements in Furnaces and Furnace Feeding Apparatus for
Utilizing Small Coal and the like as Fuel.
I, FRANZ FORST, of No. 28, Judengasse, Strassburg, Alsace, in the Empire of
Germany, Manufacturer, 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:-
-
"
The object of the present invention is a coal dust furnace, comprising mixing and
feeding apparatus arranged in such a manner that the coal dust fed into a hopper
is rapidly conveyed or projected by the action of a screw or similar feeding device
in the shape of a cone revolving within the lower orifice of the said hopper, into a
vertical cylinder, wherein such coal dust is intercepted by a current or jet of air,
introduced into the apparatus tangentially, and forced or driven downwards by
the tangential blast, over a continuous surface preferably fitted with helical ribs.
This not only causes the coal dust to thoroughly mix with the blast or air
employed in promoting combustion, but also ensures the separation or removal of
comparatively large particles or pieces of coal or incombustible impurities. These
objectionable admixtures, on being separated, descend to another hopper arranged
at the bottom of the cylinder, and may thence be eventually discharged.
The mixture of coal dust and air, however, is conducted by suitable flues or
pipes to a smokeless fireplace consisting of a bed or sole. built up of firebricks in
the shape of a flight of rearwardly descending steps, behind which, but in front
of the fire bridge, there is provided a pit or shoot, fitted with means for closing
it, and adapted for the double purpose of the discharge of the slag and the starting
of the fire.
The invention will be best understood by reference to the accompanying drawing
in which-
Figure 1 is a longitudinal section of the fireplace or furnace proper fitted with
the improved mixing and feeding apparatus ;
Figure 2 is an horizontal section of the mixing and feeding apparatus taken on
the line of Figure 1.
Figure 3 is an elevation of a slightly modified form of conveyor screw serving
both for feeding and dividing the material; and
Figure 4 is a front view of the furnace proper.
As will be best seen from Figures 1 and 2, the apparatus mainly consists of
a vertical cylinder a. supporting the hopper 6 and serving for the reception of
coal dust.
Within the orifice of this hopper, there is fitted a screw c of a peculiar conical
shape. It is firmly secured to a shaft g supported in the lower cross piece or
bridge d and driven at the top through the medium of bevel gearing and shaft f.
As it revolves it throws off the coal dust, in the shape of a hollow cone, into the
vertical cylinder a and, in so doing, crushes any coal dust which may,-through
moisture for example,-have conglomerated into lumps.
The conical screw c, Figure 1, may, if preferred, be replaced by the distributing
cone h shown in Figure 3. This may be a case hardened casting, or it may be
made of steel; and it is provided with ribs or grooves varying in size, and
gradually narrowing down as they descend.
In order to avoid too rapid wear and actual breakages, the said distributing
cone is supported by the point of the screw. k adjustable within the bent spring
(or spring-controlled yoke) i, and is adapted to move within the casing / internally
grooved or ribbed.

page_text: The object of this arrangement is to grind small coal and pit coal (mineral coal)
or coal dust, so as to prevent comparatively large pieces of coal from entering the
cylinder a.
"
Within the casing a, at the top, there is arranged a fan m through which a
current or blast of air is tangentially produced; other means, however, may be
employed for the same purpose if desired. The blast intercepts the coal dust
projected by the distributing screw c into the cylinder a, and conducts it over the
helical surface n preferably consisting of ribbed plates. The material thus takes
a spiral downward course and, in so doing, thoroughly mixes with the air, while at
the same time comparatively large pieces of coal or impurities are separated.
These, accordingly, drop into the hopper o, whence they are discharged through
the orifice p adapted to be closed by means of a slide or damper r.
The current of air charged with coal dust is now conducted to the fire by the
pipes branching off tangentially from the cylinder a. The fireplace or furnace
proper, to which this blast, together with the coal dust, is carried, consists, as
shown in Figure 1, of a block of masonry or fireproof brickwork wherein the
usual grate is substituted by a rearwardly sloping sole or flooring t of firebricks,
having a series of steps extending across it. At the end of this structure, and in
front of the fire bridge u, there is provided a shoot or shaft v leading to another
shoot or channel w, and serving both for discharging the slag and for starting
the fire.
For the temporary removal of the slag, collecting in the said channel,-
without any interference with the draught, the shaft v is adapted to be closed by
means of a sliding lid or damper x.
The fire is controllable through two apertures 2. provided next to the dust
conveying pipe or flue s, and it is started by means of a kind of slow match
soaked with petroleum, which is inserted through the lower shoot, underneath
the upper shoot or shaft, after the coal dust feeding apparatus has been set in
⚫operation.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that
what claim is :-
1. A coal dust furnace consisting of a mixing and feeding apparatus, wherein
the coal dust charged into a suitable receptacle, such as a hopper b, through the
medium of a conveying or distributing cone, such as c h, or the like,-which may
also be adapted for crushing or dividing comparatively large particles or lumps of
the combustible material, the material being rapidly transferred or projected into
a vertical cylinder, such as a, in the shape of a hollow cone, and there intercepted
by a tangentially inflowing air current or blast, which, in taking a spiral downward
course, takes such material along with it to the fireplace or furnace proper; while
at the same time the coal dust is thoroughly mixed with the air, and the coarser
lumps of material and impurities are separated.
2. A furnace with a firebrick bed or flooring, such as t in the shape of a
rearwardly descending gradient having a series of steps, in the rear of which, but
in front of the fire bridge, such as u, a channel such as v, leading down to another
channel such as w, is provided for the discharge of the slag and for starting
the fire.
.
3. A hopper, such as o, arranged within the cylinder a of the feeding and
mixing apparatus and having an orifice p. fitted with means for closing it and
serving for the discharge of the coarser lumps of coal or the like.
Dated this '14th day of September 1895.
"
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.