Improvements in Mechanical Stokers.
Year: 1890

page_text: Date of Application, 13th Feb., 1890
Complete Specification Left, 13th Dec., 1890-Accepted, 17th Jan., 1891
PROVISIONAL SPECIFICATION.
Improvements in Mechanical Stokers.
I, THOMAS WRIGLEY, of Waterside House, Todmorden, in the County of
York, Mill Manager, do hereby declare the nature of this invention to be as
follows:-
My invention relates to mechanical stokers for boilers and consists in improved
arrangements or constructions, of said stokers, the object of my invention being to
feed the furnace with coal on the underside of the incandescent fuel and thus prevent
the formation of smoke.
In carrying my invention into effect, I feed the fuel into a hopper of the stoker
from which the coal drops into a horizontally reciprocating distributor or its
equivalent and is fed by the same into two shoots or pipes leading to troughs
arranged at each side of the grate. These troughs on channels extend along the
grate bars at each side and are closed at the top for part of their length and open for
the remainder the edges being level or approximately level with the top of the
grate bars.
The troughs may be of uniform depth throughout their length, or be
inade deeper at the front than at the back, so that with level grate bars the bottom
side of the troughs slopes upwards, and is level or approximately so when with grates
sloping downwards towards the back. The troughs extend in front of the boiler so that
the coal from the shoots or pipes before referred to can drop into them, and are each
provided with a reciprocating piston, pusher or other mechanical appliance which
forces the coal along the troughs. The latter may extend to the full length of the
grate bars or only to part of their length. The firebridge or the resistance of the fuel
on the grate stops the coal at the end of the troughs and causes it to rise up against
the sides of the boiler flue, which cause the coal when risen to a certain height to
fall over upon the grate bars at the sides of the trough. The fresh coal being forced
along the bottom of the trough is thus fed from below the already burning coal and
any gases rising from the fresh fuel are ignited thereby and consumed.
receive by preference a lifting and forwarding motion by any of the usual means
employed for this purpose, and may be so arranged that they convey the fuel towards
the bridge, which in that case is so arranged that the clinkers or ashes can drop down
before or behind it into the ashpit, or they may be arranged so as to convey the fuel
towards the front, arrangements being made in this case allowing the ashes or clinkers
to drop down into the ashpit at the front of the grate. In some cases where short
troughs extending only to part of the length of the firebars are used, the bars behind
the trough may be actuated so as to convey the fuel towards the bridge, and the
firebars between the troughs so that they convey the fuel towards the front.
The firebars
In some cases one or more intermediate troughs may be arranged between those at
each side of the grate, each trough being provided with a reciprocating piston, pusher
or other mechanical appliance for forcing the coal along, and a shoot or pipe for con-
veying the coal from the hopper to the troughs, the distributor being arranged to
supply these different shoots alternately. In some cases the distributor may be
omitted and the hopper with or without a feed roller or crusher arranged so as to
supply the different shoots and troughs.
The revolving and reciprocating parts of the stoker may be actuated by any
suitable means ordinarily used for these purposes.
10th day of Fahun 1900.

page_text: COMPLETE SPECIFICATION.
Improvements in Mechanical Stokers.
I, THOMAS WRIGLEY of Waterside House, Todmorden in the County of York,
Mill Manager, 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 statment :-
My invention relates to mechanical stokers for boilers and consists in improved
farrangements or constructions of said stokers, the object of my invention being to
eed the furnace with coal on the underside of the incandescent fuel and thus prevent
the formation of smoke.
In carrying my invention into effect, I feed the coal into a hopper of the stokér
from which the coal drops either into a reciprocating distributor or its equivalent,
delivering it into a shoot or shoots, or directly into said shoot or shoots leading to a
trough or troughs each provided with a reciprocating piston pusher or other mechanical
appliance by which the coal is forced along the trough or troughs: The latter extend
in the direction of the firebars to the firebridge and are closed for part of their length
and open at the remaining part. The firebridge or the resistance of the fuel on the
grate stops the coal at the end of the troughs and causes it to rise up and fall over
upon the grate bars at the back part of the grate. The fresh coal forced along the
trough is pushed up under the already delivered and burning coal and any gases
arising from the fresh fuel are ignited thereby and consumed. The firebars or
scrapers between the firebars receive a reciprocating motion in such a manner that the
coal is conveyed from the back part of the grate towards the front, where the clinkers
and ashes are removed either by a drop plate or through the furnace door.
On the three heets of drawings appended hereunto, Figures 1 to 5 show one
arrangement of my improved mechanical stoker applied to a double flued boiler;
Figure 1 showing a front view of the stoker for one flue and the driving
apparatus.
Figure 2 a cross-section through the same.
Figure 3 a longitudinal section through the furnace.
Figure 4 a longitudinal section through one of the troughs.
F güre 5 a partial plan of the grate and trough.
Figure 6 shows a modified arrangement of my iinproved stoker, partly in front view
and partly in section.
Figure 7 a sectional plan of the driving apparatus for the same.
Figure 8 a longitudinal section through the trough of the same.
Referring to Figures 1 to 5, the fuel is fed into a hopper of usual construction
placed above the shoots a a and not shewn on the drawing, from which hopper it
descends through said shoots a a and drops into the open front end of the troughs bb
behind the pushers or pistons c c. The latter receive a reciprocating motion froin thiè
cranks d¹ di on the cranked shaft d which cranks enter slots in the lugs c¹ c¹ cast
on the pushers c c. The troughs bb slope upwards towards the firebridge e and are
closed at the top for part of their length but open at the part nearest to the fire-
bridge, as shown on Figures 4 and 5, while the firebars f slope towards the bridge.
The pushers cc force the coal along the troughs till its progress is arrested at the
bridge; when the further forcing of coal along the troughs will cause the coal
to rise up against the bridge and the sides of the flue fi and to fall over upon
the back part of the grate bars f where it is ignited. The further supply of
fresh coal is pushed up from below under the already burning coal and the
gases evolved from the fresh fuel having to pass through the ignited fuel will
become burnt and the production of siroke prevented.
The coal is gradually
brought to the front of the grate by reciprocating scrapers g.
fixed upon cross bars g¹ g with distance pieces between them and the bars g¹¹ are
passed through and carried by horizontal bars 92 92 which are extended to the front
and formed with slots into which the cranks d d² of the shaft d enter and impart
These are

page_text: to the bars g² g² and scrapers g a reciprocating motion. The bars g² g² are formed
with projections or catches g g³ which catch behind one of the pegs h¹ on levers h
when the bars are in their most backward position. As they are pulled forward,
the catches pull the pegs h and thereby turn the shafts 2, on which the levers h are
fixed, in their bearers h, whereby the bars and scrapers g are lifted into the coal
and carry it forward. After passing over their top centres or the position shewn on
Figure 3, the weight of the bars and scrapers turns the levers h forward in the
direction indicated by the arrow and the scrapers drop out of the coal, the bars g²
resting upon both pegs in each lever h. The scrapers are moved backwards by the
cranks d² while the top of the scrapers is then below the level of the grate bars,
notches g being formed in the bars g² into which the front pegs h' can enter while
the hind pegs are depressed by the catches g³ moving backwards. In this manner
the scrapers gradually move the coal forward from the back end to the front end
of the grate, and the elinkers and ashes formed are removed by means of the drop
plate or through the door k.
The shaft is driven from the band pulley 1. The shaft of the band pulley has
a worm 2 fixed on it driving the worm wheel me on the vertical shaft m²; worm m²
on the latter drives the wornwheel m³ on the shaft d which thus receives a slow
rotation.
.
In the arrangement shown by Figures 6 to 8, a circular trough or pipe niš
arranged for each flue below the grate bars. The coal drops through the legs ör
shoots o¹ o from the hopper o into the enlarged ends 03 of the shoots. A worm or
conveyor in each trough wheti rotated as indicated by the arrow carries the coal
forward towards the bridge e, where the troughs n are widened out into funnels n¹
through which the coal rises up and is delivered upon the back end of the grate, the
fresh coal being pushed up from underneath the previously delivered and already
ignited coal, the gases evolved from the fresh coal thus passing through the ignited
fuel and being consumed. The coal is brought forward by scrapers, which may be
arranged similarly as herein before described with reference to Figs. 1 to 5, or as
shewn by Figs. 6 to 8. The scrapers are mounted as before upon rods g' passing
through bars g. These bars run on rollers 3 held between collars g' on a shaft g
and are held at the front end by the cranks si of a cranked shaft s arranged in front
of the shoots, o¹. As the crank 8 rotates in the direction indicated by the arrow the
front end is first depressed and moved forwards, and then allowed to rise and moved
backwards in consequence of which the scrapers g are first lifted into the coal and
at the same time moved forward, and then allowed to drop out of the coal below the
surface of the grate bars and moved backward in this position. The coal is thus
moved forward. to the front of the grate.
The driving conveyors and crank shafts may be arranged as shewn in the
drawings. The band pulley t on shaft t being driven, rotates through the mitre
wheels 23 the vertical shaft . A worm to on the latter rotates the two worm-
wheels and 82 on the shaft u and 83. The two shafts run in bearings in the
bracket bolted to the hopper front. The shaft 3 is connected to the shaft s on
each side by coupling boxes 84, and thus rotated. The shaft u carries worms u² at
end, gearing with worm wheels p1 on the spindles p2 of the conveyors p, which are
thus rotated at a slow speed. The amount of fuel supplied can be varied by varying
the speed of the band pulley which contains several grooves for this purpose.
I do not confine myself to the details of the two arrangements of mechanical stokers
shewn on the drawings. The driving may be varied to suit different localities and
circumstances of the general boiler plant. The arrangements of scrapers are shewn
and described only as examples how the coal may be brought forward from the back
end of the grate towards the front end, and instead thereof any suitable known or
used, arrangement of reciprocating moveable firebars may be employed for this
purpose. The troughs extending along each side of the grate as shewn by Figs. 1 to 5
may be fitted with conveyors for forwarding the coal instead of reciprocating pushers.
Two troughs with conveyors similar to those described with reference to Figs. 6 to 8
may be arranged for each grate and the conveyors rotated by similar arrangement of

page_text: wheels, shafts and worms, or pushers may be used in connection with them for
forwarding the coal. For wide grates intermediate troughs may be arranged between
the troughs at each side of the grate, to which intermediate troughs the coal is
supplied from the hopper and in which it is forwarded in a similar manner as herein-
before described. The troughs may extend to the fire bridge or only to within a
short distance from the bridge. The hopper may be fitted with feed rollers and
crushers of any suitable known kind to supply the different shoots and troughs. The
revolving and reciprocating parts may be actuated by any suitable means ordinarily
used for this purpose.
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:
Firstly. In mechanical stokers the arrangement of one or more troughs extending
from the front of the grate to or nearly to the back end of the same, into which
troughs the fuel is fed from a hopper through shoots and which are fitted with
reciprocating pushers, rotating conveyors or equivalent means for forcing the fuel
along the covered front part of said troughs and discharging the fuel from the open
back part of said troughs upon the back part of the grate in such a manner, that the
fresh supply of fuel is pushed up from below under the previously supplied fuel,
substantially as hereinbefore 'described and illustrated by the drawings.
Secondly. In mechanical stokers the arrangement of one or more troughs extending
from the front of the grate to or nearly to the back end of the same, into which
troughs the fuel is fed from a hopper through shoots and which are fitted with
reciprocating pushers rotating conveyors or equivalent means for forcing the fuel
along the covered front part of said troughs and discharging the fuel from the open
back part of said troughs upon the back part of the grate in such a manner that the
fresh supply of fuel is pushed up from below under the previously supplied fuel, in
combination with reciprocating scrapers or firebars or their equivalents arranged, and
actuated so as to convey the fuel delivered upon the back part of the grate towards
the front end of said grate, substantially as herein before described and illustrated by
the drawings.
Dated this 10th day of December 1890