Improvements in Smokeless Boiler Furnaces.
Year: 1893

page_text: Date of Application, 21st Mar., 1893-4ccepted, 12th Aug., 1893
COMPLETE SPECIFICATION.
Improvements in Smokeless Boiler Furnaces.
I, ALBERT BARBER CROWDER, Gentleman, of Room 22, Larlede Building,
St. Louis, in the State of Missoma, United States of America, 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 :-
My invention relates to endless-grate stoking mechanism for furnaces, and
consists in the improved apparatus for and mode of subjecting the fuel to the heat
of the furnace itself, in a coking or heating chamber beneath the boiler, and
continuously feeding a thin layer of previously prepared fuel from said coking-
chamber into the fire to the combustion-chamber, all as hereinafter set forth and
claimed.
In the drawings:
Fig. 1 is a vertical longitudinal section through a boiler furnace having my
invention applied thereto.
Fig. 2 is a vertical transverse-section, on line X X of Fig. 1.
Fig. 3 is an elevation of the rear-end of the furnace, with parts broken away.
Referring to the drawings:
My invention exhibits several peculiar points, in that the extreme rear-wall 1 is
constructed to form an opening 2, unobstructed from side-wall to side-wall in which
is located the rear portion of a flat dead-plate 3, a roof-plate 4, and the continuously
moving endless-grate 5, which latter is of such length and construction as to
extend from end to end of the furnace walls and project beyond same at opposite
ends.
6 indicates an arched wall under the front end of the horizontal-boiler 7.
8 indicates an opening formed beneath the arched-wall 6, in which is located the
forward portion of the endless-grate 5. A swinging door 9 is hinged at its upper
edge to the boiler-front, so that it will gravitate downward and normally tend to
close the passage above said endless grate.
10 indicates the side walls of the furnace; 11 the bridge-wall: 12 the combustion-
chamber and 13 a wide-coking-chamber located in rear of said bridge-wall and
beneath the boiler 7. The coking-chamber 13 preferably consists of a rectangular
chamber having a clear width several times greater than its height, and in excess
of the width of the grate, and having fiat imperforate lower and upper dead-
plates 3 and 4, respectively, extending from the rear of the furnace beneath
the boiler to, and under the arched bridge-wall 11, terminating forward of the
front side of said bridge-wall, and extending trausversely the full width of the
furnace.
It will be observed that the forward end of the coking-chamber 13 opens into
the combustion-chamber, at the bridge-wall, and that the rear end of same opens
into a hopper 14, which latter is located exterior of the rear wall 1, but with its
lower end above the rear portion of the endless-grate, so that fuel placed in said
hopper may be discharged upon said grate and carried into the coking-chamber.
This hopper may be of any ordinary construction, or it may be dispensed with entirely
and fuel thrown upon the projecting-portion of the endless-grate as fast as
combustion necessitates.
The endless-grate may be formed of grate-bars of any known style. It is
mounted upon suitable sprocket-wheels 15 and 16, placed respectively at the front
and rear of the furnace upon suitable shafts journaled in bearings. A number of
supporting wheels 17 are mounted beneath the slack-side of the endless-grate, and
serve to support same during operation, and prevent contact thereof with the flor

page_text: and walls of the furnace. The tight side of the endless-grate 5 rests in contact
with, and is supported by, the lower dead-plate 3 throughout the length of said
plate, and extends in a direct line from end wall to end wall of the furnace, the
forward portion of said tight-side extending forward of said dead-plate and
forming the grate-surface in the combustion-chamber.
An important portion of my invention lies in the relative direction of travel of the
endless grate, and the direction of draft in the combustion-chamber and in the
space beneath the boiler, or other thing to be heated. These relative directions
are clearly shown by the arrows--the direction of draft in the combustion chamber
and in the space beneath the boiler being from front to rear, and the direction of
travel of said endless-grate being from rear to front through the coking-chamber
and the combustion-chamber.
As the arrangement of mechanism for imparting a continuous movement to the
endless-grate does not involve invention, and can be devised by any skilful
mechanie, I do not show or describe any complete mechanism for such purpose,
except that in Fig. 3, I show a gear or worm-wheel 18 mounted on the shaft which
carries the sprocket-wheel at the rear of the furnace, and which may of course be
engaged by driving mechanisin in any known manner,
The amount of fuel permitted to enter the coking chamber can be regulated in
various well known manners-for instance, in case no hopper is employed the amount
can be controlled by throwing more or less fuel on to the projecting-portion of the
endless grate at the rear of the furnace.
The
Another construction is that which I here show, consisting of a vertically-
adjustable feed-gate 19 mounted within suitable guides within the hopper 14, with
its opposite ends projecting on opposite sides of said hopper and provided with a
toothed-rack 20, which latter is engaged by a pinion mounted on a transverse
shaft 21. This shaft is mounted to revolve in bearings fixed to the rear of the
fornace, or to some other adjacent support, and is provided with a hand-wheel, or
other device by means of which it may be revolved in either direction.
function of this foed-gate is to admit no more fuel than its determinate height above
the endless-grate will permit, and to level and smooth the fuel upon the grate.
also acts to exelle air from the coking-chamber to a more or less degree.
The upper and lower dead-plates of the coking-chamber may be constructed of
iron boiler-plate, or of fire-clay or of other material suitably supported in the
positions before described.
It
It is essential to the coking operation that the upper dead-plate of the coking-
chamber be constructed quite thin of good heat-conducting material, if such a plate
is used at all, otherwise the object of such chamber will be defeated and the fuel
that is being continuously passed to the fire will not receive a previous heating
and coking in the coking-chamber.
In practice have found, that in some cases the upper dend-plate 4 of the
coking-chamber may be discarded, leaving said chamber open on its upper side, so
that the fuel carried into it by the forwardly moving endless-grate will immediately
upon its entrance into said coking-chamber be subjected to the direct action of the
heat and flame issuing from the combustion-chamber. Such construction will cause
the fuel to be more rapidly heated and coked than if the upper dead-plate were
employed.
In some cases 1 may discard the bridge-wall 11, ordinarily built of brick, and
utilize the forward end of the coking-chamber as a bridge-wall. It is essential,
however, that the lower dead-plate be utilized, whether it be in the form here
shown, or whether it consist of a dead wall of brick or fire-clay, as otherwise the
fuel would ignite and burn from front to rear of the furnace.
22 indicates an open space between the forward end of the lower dead-plate and
the passage 8 in the front wall of the furnace, the function of which is obviously to
permit free passage of air upward from the ash-pit through the grate to the
combustion-chamber. Although the furnace will operate satisfactorily with this
opening, or spree, fixed in length and area, yet I have found it desirable in some

page_text: cases to enlarge and diminish this space. For instance, in situations where the
furnace is being worked to its full capacity said space should be enlarged to the
greatest extent, while if there be but slight demand made upon the furnace, then
said space may be diminished in area. Diminishing or enlarging the space 22 acts
to diminish the grate-surface, as is readily observable, and with results well-known
to these skilled in the care of furnaces.
To accomplish the enlargement of the space 22 I have provided a sliding
plate 23, which is here shown provided with slots 24 and held in position beneath
the forward portion of the lower dead plate 2 by means of bolts 25 gaging said
slots and securing said plate in said position.
The operation is as follows: The hopper 14 heing supplied with fuel in the form
of small lump bituminous coal, or "slack" or wood saw-dust or shavings, such fuel
gravitates downward into the endless-grate, and as said grate continuously travels
towards the forward end of the boiler said fuel is carried first into the rear portion
of the coking-chamber, and passing slowly therethrough is thoroughly heated and
coked and prepared for introduction to the combustion chamber, into which latter
its previously heated body is then carried in the form of a charred thin layer or
mass of a temperature near to that of the combustion-chamber. In this prepared
condition the charred mass of fuel is in condition to become quickly ignited, and to
burn without the production of smoke, all of which it docs. After reaching the
combustion-chamber the fuel is carried slowly but continuously, in a state of
combustion, toward the front of the furnace (in a direction opposite to that of the
draft) and the residue is deposited in the forin of ashes upon the ground or floor in
front of the furnace, having automatically elevated and swung outward (as shown
by dotted lines) the swinging-door 9. The coking-operation is constant, being
accomplished by the heat of the furnace in its passage above the coking-chamber.
There will be no intervals of smoking, so long as fuel is in the hopper and is fed as
above described.
I am aware that a furnace having a bridge-wall arched across it and an endless-
grate travelling beneath said bridge-wall, is not broadly new. But in such
arrangements having an arched bridge-wall, the endless-grate does not extend from
end to end of the furnace-walls and project beyond same at opposite ends; and
said grate did not travel continuously over and in contact with a dead-plate or
through a chamber arranged to coke or char the fuel; in some of such arrangements
there was no coking-chamber; and in others there was no endless-grate travelling
therein.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. A furnace having a combustion-chamber in which the draft is in a given
direction, & coking-chamber constructed with a lower dead-plate or wall, to coke
and expose fuel to the heat of this combustion-chamber, and an endless-grate
arranged to travel in contact with said dead-plate or wall of the coking-chamber
and carrying raw fuel thereinto, and coked fuel from same into the combustion-
chamber, substantially as specified.
2. A furnace having a combustion-chamber at its front-end in which the direction
of the draft is fixed, à coking-chamber constructed with a dead-plate to coke and
expose fuel to the heat of the combustion-chamber in rear of said combustion-
chamber, beneath the object to be heated and having a width equal to or in excess
of the width of the grate in the combustion-chamber, and an endless grate arranged
to travel in a direction opposite to the direction of draft in said combustion-
chamber and to carry fuel from the rear end of the furnace first into said coking-
chamber and then into the combustion-chamber, substantially as and for the purpose
set forth.
3. A furnace having a feed-hopper at its rear, a combustion-chamber at its
front in which the direction of the draft is in a certain direction, a coking-chamber

page_text: constructed with a dead-plate to coke and expose fuel to the heat of the combustion-
chamber and located intermedinte of said combustion chamber and the rear of the
furnace beneath the object to be heated, and an endless-grate mounted to travel
from rear to front of said furnace in said coking and combustion-chambers, and
carry raw-fuel into the coking-chamber and remove coked-fuel from same,
substantially as set forth.
4. A furnace having a combustion-chamber, a dead-plate or wall approximating
in width the width of and located in rear of said chamber and arranged to travel in
close contact with said dead-plate and carry fuel to said combustion-chamber, the
direction of movement of said grate and the fuel carried thereby being opposite to
the direction of draft in said combustion-chamber, substantially as set forth.
5. The mode of continuously treating and feeding fuel in a furnace, which
consists in first preparing a uniform thin layer of raw fuel approximating in width
the width of the furnace-grate, subjecting this uniform thin layer of fuel to direct
heat of the furnace in a cuking-chamber beneath the object to be heated, heating
and coking it in said coking-chamber, and continuously conveying the thin layer of
fuel as fast as prepared uninterruptedly toward said combustion-chamber and into
the same in a direction opposite the direction of draft in said combustion-chamber,
substantially as set forth.
Buch der of March 1892
ALLISON BROS.,
Agents for the Applicant.