Improvements in Mechanical Stokers and Furnaces.
Year: 1895

page_text: Date of Application, 10th Oct., 1995
PROVISIONAL SPECIFICATION.
Improvements in Mechanical Stokers and Furnaces.
WILLIAM FRASER, Engineer 99 Anderton Road Sparkbrook, Birmingham do
hereby declare the nature of this invention to be as follows:-
To automatically supply a furnace with fuel and discharge the clinker at the
same time and also to utilize the furnace bars for superheating the air before
coming into actual contact with the fuel. In adopting my invention to a
Lancashire boiler the ordinary fire bars, bridges and furnace doors are removed.
An iron plate or platform about twelve or fourteen inches broad and about six or
seven feet long is fixed across the boiler a little above the centre line of the
furnaces. On the same platform rests two furnace hoods or covers, both projecting
to the outside edge of the plate or platform and making an airtight joint at the
back, i.e. round the circular or upper half of the furnace tube. Both hoods are
fitted with doors in the front for the purpose of firing by hand if necessary; the
top of the hoods are fitted with dampers or regulators for the supply and regulation
of the fuel, the same can either be delivered into the fuel receiver by means of
elevators or thrown into same by means of a shovel, or otherwise. Immediately
below-where the fuel drops into the furnace a horizontal sliding plate about two
inches deep and about half the breadth of the said platform plate and almost the
entire length of the inside of the hood or cover works backwards and forwards for
the purpose of pushing the fuel on to the furnace bars which lie at a slight angle
towards the bridge. ie. the bridge is several inches lower than the platform plate
and each alternate furnace bar is movable for the purpose of sending the fiel
forward. To facilitate same the moving bars are provided with teeth or notched
on the top or upper side.
The bridge for supporting the bars is hollow and kept full of water for the
purpose of keeping the end of the bars cool. All the air for combustion being
drawn through the furnace bars not only lengthens their life but add's greatly to
help combustion.
The ashole is fitted with a close fitting door to ensure the air passing through
the furnace bars. All the clinker or refuse is carried over the bridge and
accumulates there until removed. There is an aperture in the bridge and by
means of a revolving worm running horizontally along the bottom of the ashpit the
refuse or clinker is removed and drops outside the boiler; or it can be extracted
by using a shovel with a long handle to get behind the bridge, or otherwise.
The furnace bars and the horizontal feed plate and warm are worked by means
of eccentrics, cranks and levers, driven by a horizontal shaft attached to the
anderside of the platform plate in front of the boiler.
Improvements in Mechanical Stokers and Furnaces.
WILLIAM FRASER, Engineer late of 99 Anderton Road Sparkbrook Birmingham
now of Dovedale School Road Moseley Birmingham 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 :-
This invention relates to improvements in the construction, arrangement, and
[Pru 811

page_text: working of mechanical stokers and furunces, whereby the coat or fuel is first
automatically riddled or sorted, then fed on to the fire within the formee in
the best way for combustion, and when on the fire, kept in a constant at of
ngitation until burnt out, when finally its ashes are deposited into the ash pit ad
the clinker withdrawn therefrom by a suitable conveyor to the front of the boiler
or furnace for removal,
Furthermore, by my invention the bridge, at the back of the fire bars and
within the furnace, is kept cool, thereby preventing the ends of the fire bars being
burnt, and the construction of the said fire bars is such as to superheat the air for
promoting combustion before it reaches the fire within the furnace, thus ensuring
the very best results as regards economy and combustion, and lengthening the life
of the said bars.
Fig. 1 of the accompanying sheets of drawings represents, in side elevation with
parts in section, a portion of a Lancashire boiler fitted with a mechanical stoker
constructed according to my invention.
Fig. 2 is a part section and part elevation of Fig. 1 and clearly shows the means
of driving the various working parts of the mechanisms.
Fig. 3 represents side and edge views of one of the fire bars separately
whilst
Fig. 4 is a plan and Fig. 5 an end view of the slack receiver and its ejector
mechanism.
Fig. 6 represents a sectional view illustrating the hollow construction of the
bridge, and also the positions of the water supply pipes by which a circulation of
water is effected; holes being also provided in the walls of the said bridge for the
escape of any steam formned therein.
Figs. 7 and 8 show a modified form of bridge construction to form a bearing for
n screw conveyor us hereinafter described.
n
Fig. 9 is a section on a larger scale than Fig. 1 to more clearly illustrate the
working of the different parts of the mechanisms; whilst
Fig. 10 represents a modification of a duplicating movement of the fire bars.
The same letters of reference indicate like parts in the whole of the figures of
both sheets of drawings.
The boiler is provided and fitted with a hood surmounted by a hopper
wherein the fuel is placed to be automatically fed to the furnace. The shape of
this said hopper and also the shape of the hood is clearly shown in Fig. 2 the
former being provided with a swinging bottom connected by trunnions & and
supported upon cam plates & made fast upon a transverse shatt supported within
the sides of the upper parts of the hood 6. These cam plates constitute a
means for adjusting the angle of the swing bottom and the amount of feed of
the fuel is regulated to meet the requirements of the furnace.
Projecting within the metallic hopper and from the frout side is another cross
plate o connected movably to another plate e provided with a hinged lid and
upon this first mentioned plate e and the bottom as aforesaid the fuel is supported
a spare e being left between them for the passage of the same to the top of an
angularly disposed grid or riddled fulcrumed at its one end upon a bell-crank
lever connected to a rocking bar for the purpose of regulating the angular
adjustment of the said grid or riddle. This said riddle and its parts are contained
within the hollow interior of the hood and the free ends of the same rest upon a
pair of revolving four-sided dises mounted upon a shaft driven by a chain
wheel through a chain and a chain pinion which latter receives its motion
from a counter axis e through chain wheels ee and chain e. The continued
rotation of the four sided discs d' gives to the riddle da rising and falling
or shaking movement by which the fuel from the hopper is sorted the rough
portion of the same being retained upon the riddle until falling by its own
gravitation whilst the fine or slack part of the fuel falls through the spaces
of the riddle into an obliquely disposed receiver mounted upon trunnions
as shown in Figures and 9 affixed to the sides of the hood b. This

page_text: receiver is mounted within the hollow interior of the hood and fits the same
and is provided with a centrally disposed star wheel ƒ³ as shewn in Figures 1 and 4
built with a number of steel arms which come successively into contact in the
rotation of said wheel with an outstanding peg or projection as shewn in
Figure 4 causing each arm in its turn to be deflected until the same slip by the
said projection when a flirting or flinging movement is given to the fine slack in
front of each arm and the same is sprinkled upon the top of the live coal or rough
fuel which has previously fallen from off the grating or riddle d. The rotation of
the star wheel is effected by means of a bevel wheel and a pinion the former
being fast upon the axis of the star wheel and the latter mounted upon the axis
of the chain pinion d³ before described. The angular adjustment of the receiver
is effected by means of screwed bolts and nuts fpassing longitudinally through
the walls of the hood & and taking into screwed lugs 10 upon each side of the
said receiver.
7
The fuel as it respectively leaves the riddled and receiver falls upon the fire
bars and the dead plate i the former being at the one end supported upon the
furnace bridge and at the other end upon a transverse roller mounted within
the walls of the boiler a. These said fire bars g are cast hollow and are arranged
in stationary and movable series, that is to say, every alternate fire bar is intended
to be reciprocated back and forth and to have a rising and falling movement given
to it, the same being accomplished by means of mechanisms as hereinafter described
the object of these movements being to keep the whole of the fire in the furnace
in a constant state of movement or agitation which effectively increases the com-
bustion of the fuel. Each and every alternate fire bar is connected at its one end
to a link g³ connected to a long bar 3 of a pair of rocking levers g mounted upon
fulcrum pins the other arm of these said levers being connected to arms g
fast with eccentrics y mounted upon the main shaft which is driven through
bevel and worm gearings g¹º, g¹, g¹ and a speed pulley 9" which latter is driven
from some motive power.
The other end of each and every alternate fire bar is provided with a four-sided
cam plate g connected thereto by a joint pin . These four-sided cam plates
work against a
projection or within a groove 20 formed upon or within the top
side of the bridge and when the said bars are reciprocated by means of the
mechanisms described the said cam plates give a rising and falling movement to the
said fire bars.
Mounted to slide upon the dead plate i which extends across the front of
the furnace a is a pusher plate i connected at each of its ends to the long bar g
by a forked part and by which the said pusher plate is worked. The object of
giving a back and forth movement to this pusher plate is to force forward onto
the fire all fuel which may drop from the riddle d'and receiver f to a position in
front of the fire burs, and this forward movement is effected at the same time as
the fire bars are moved forward by the eccentrics and links g the parts giving
the movements being common to both the bars and the pusher plate.
The shaft g' upon which the eccentrics are mounted is rotated by bevel gearing glo
driven from a worm wheel gi receiving its movement from a worm the latter
being driven from the pulley " and the whole of the parts are mounted in bracket
bearings, A quadrant k is provided having a handle and fitted to the
rocking shatt d³ of the riddle d to aflix the latter when adjusted and the hinged
lide of the hopper is provided for the purpose of ascertaining the amount of
fuel contained in the hopper and to view the general working of the feed.
Upon the principal shaft. g is fixed a bevel wheel driving another bevel
wheel fast upon a short spindle suitably mounted and having another bevel
wheel adapted to drive a like bevel wheel made fast upon the end of a screw
conveyor m disposed longitudinally and centrally in bracket bearings attached to
the dead plate and bridge respectively.
This screw conveyor m is adapted to rotate and bring forward all clinker from

page_text: the back of the bridge to the front of the boiler when it can be rm and to
effect this the end of the conveyor will be made to extend through am! rear of
the bridge h.
Each and every fire bar which is made hollow as before described is open at its
front end n and also at the rear and the nir to be superheated passes into the
fire bars from the front end along to the back all the while increasing in temp riture
then from the back through the space into the ash pit in front of the age
where it diffuses itself through the spaces between the said bars and promotes
good combustion of the fuel.
The front of the ash pit is closed by an air tight door y connected to the furance
by hinging or otherwise which prevents the ingress of cold air and the egress of
hot air. This sealing of the front of the ash pit is for the purpose of creating an
increased current of air through the fire bars.
In the modification shown in Figure 10 where the whole of the fire bars are
constructed to move instead of only the alternate ones the movement is effected
from the eccentrics gas before described but independent arms oo are provided
whereby the one series of fire bars will be moved at the same time in an opposite
direction to the other series each series being independently supported at their
front ends by rollers p p.
The circulation of the water throughout the interior of the bridge is per-
formed by means of an inlet pipe running longitudinally along the side of the
fue and into the bridge as aforesaid the said pipe being connected to a vertical
pipe having an enlarged mouth into which a water supply is directed.
Longitudinally directed from the bridge at a little higher level than the pipe q
is an outlet pipe terminating in a bend situate at the front of the furnace
and by these said pipes a continued circulation of water within the bridge his
effected, the outlet pipe being practically a tell tale as to the amount of water in
the bridge. Furthermore besides keeping the bridge cool steam is generated
within the said bridge which escapes through the perforations into the ash pit and
keeps the ends of the bars from burning.
The front of the furnace is supplied with ordinary doors and a secondary door
is also provided hingedly connected to the hood and fitted with rack and pawl
means and for retaining the doors in an open position or in a partially open
position as may be required.
purpose
A secondary bridge is built behind the bridge shown in Fig. 1 for the
of forming a compartment 2 wherein the red hot clinker is deposited made during
a day's working of the furnace, and by this means the heat of the clinker is utilized
thus effecting considerable saving in fuel and labour.
Referring back to Fig. 10 the lever is provided with adjusting pins
whereby the movement of the fire bars is increased or diminished 8 may be
required.
The arms of the star wheel as before described are each constructed of
different strengths so that the fiue fuel can be distributed more evenly over
the fire.
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
clnim is:
1st. In a mechanical stoker for furnaces the combination with a hopper or fuck
supply of a shaking grid or riddle for the purpose substantially as described and
set forth.
2nd. In a mechanical stoker for furnaces the mounting working and adjustment
of the shaking grid or riddle substantially as described and set forth.
3rd. In a mechanical stoker the combination with a shaking grid or riddle d and
a hopper or fuel supply 6 of a swinging bottom and its adjustment means a
sliding plate c and n hinged cover or door o substantially as set forth.

page_text: 4th. The combination with a shaking grid or riddle of an adjustable and swinging
receiver fitted with a star or armed wheel with suitable gear substantially as and
for the purpose described and set forth.
Fth. In a combined mechanical stoker and furnace a dead plate i fitted with a
ading pusher plate operated by levers and eccentrics and the like substantially
13 described and set forth.
6th. In the hood of a mechanical stoker and furnace fitting the same with
an inside or secondary swinging door s made adjustable for the purpose as set
forth.
7th. In a combined furnace and mechanical stoker, the means for giving a rising
falling and shaking movement to the fire bars in combination with the mechanism
for reciprocating the same substantially as described and set forth.
Sth. In a furnace or boiler mounting the front ends of the fire bars upon.
anti-friction rollers for the purpose described and set forth.
9th. In the fire bars of furnaces or boilers the mechanisms for traversing and
the means for adjusting the same substantially as described and set forth in
Fig. 10.
10th. In furnaces or boilers the use of a conveyor screw extending to the
back of the bridge and the means for driving the same substantially as described
and set forth.
11th. In a furnace or boiler a hollow bridge fitted with inlet and outlet pipes
for the purpose substantially as described and set forth.
12th. The general arrangement fitting working and combination of the whole of
the parts as set forth.
Deted this 8th day of August 1806
WILLIAM FRASER.