Improvements in Steam Generators and Automatic Stokers therefor.
Year: 1890

page_text: Date of Application, 24th Dec, 1890-Accepted, 7th Mar., 1891
COMPLETE SPECIFICATION.
[Communicated from abroad by NATHANIEL WATERMAN PRATT AND THE
BABCOCK AND WILCOX COMPANY, of New York, in the United States
of America.]
Improvements in Steam Generators and Automatic Stokers
therefor.
I, WALLACE FAIRWEATHER, C.E., of 62, Saint Vincent Street, in the City of
Glasgow, Registered Patent Agent and Fellow of the Institute of Patent Agents,
do hereby declare the nature of this invention, and in what manner the same
is to be performed (as communicated to me), to be particularly described and
ascertained in and by the following statement :-
This invention relates to chain grate stokers, and it has for its object to adapt the
furnace wherein such a stoker is used, to exclude the access of cold air through
the interstices that are usually left between the moving sections of the grate and
the furnace walls or other parts of the furnace or ash pit; also to adapt the con-
struction of the furnace to obtaining a maximum efficiency of heat; also to promote
convenient access to the furnace where it is required to pull the fire, or to observe
or regulate the same independent of the feeder; also to separate the residue of the
fuel that has travelled the entire length of the furnace from the portions of fuel that
may fall through the grate at intermediate points and be but partly consumed; also
to crush and distribute the coal evenly upon the grate and apportion a sufficient
amount of the body of coal toward the sides of the furnace to form a seal against
the direct access of air above the grate; also to promote water circulation in the
boiler and to protect the walls of the furnace by the introduction of water pipes
that lie proximate to the sides of the fire; and in order to enable others skilled in
the art to which my invention appertains to understand and use the same, I will
proceed to describe its construction in detail, explain its operation, and point out in
the appended claims its novel characteristics.
Referring to the accompanying drawings
Figure 1, is a sectional elevation of a water tube boiler;
Figure 2, a transverse section of Fig. 1, on the line - shewn on an enlarged
scale;
Figure 3, a front elevation of the lower portion of the boiler front, on the same
scale as Fig. 2;
Figures 4 and 5, detail views of the feeder;
Figure 6, a detail view of the sprocket wheels and their shaft at the rear end
of the chain grate
Figure 7, a horizontal section on the line y-y, of Fig. 1:
Figure 8 a sectional elevation of the furnace and ash pit with the chain grate and
feeder removed; and
Figure 9, a transverse section on the line -, Figure 8.
A, A, are the inclined water tubes, and B, the steam drum composing a well
known type of sectional boiler which I have chosen to illustrate in connection with
the invention; it of course being understood that the said invention is applicable
likewise to any other type of boiler than the special form shewn. C, is the furnace
located beneath the front or elevated ends of the water tubes and to which the
draft is supplied froin the point D, through the sections of the grates.
E, E, are water boxes at each side of the furnace doors F and which form side
walls for the doors, and enclose the receiving space of the feeder above the doors.
To the water boxes E, I connect the water tubes 1, 1, which communicate with the
mud drum G, or any suitable lower portion of the boiler, and are slightly inclined
to promote circulation extending through the furnace adjacent to the walls thereof*

page_text: and just above the grate surface to form fire backs for the fuel. The hand holes 2,
(Fig. 3) afford access to these tubes for cleaning them. To the water boxes E,
I also connect the uptake pipes H, which deliver the up current of water
from the tubes 1, to the connecting box I, intermediate to the headers and
the steam drum of the boiler, or to any suitable upper portion of the boiler. The
pulverized coal or ashes at the sides of the furnace are banked up against the
tubes I, to seal the sides of the grate, and in order to effectuate this purpose, the
tubes are made to converge from the front of the furnace toward the rear as seen
in Fig. 7, so that as the fuel is moved rearward and becomes consumed and
diminished in bulk it is crowded toward the centre of the furnace to compensate for
the reduction and to maintain the depth at the sides.
The ledges J, J, of fire brick overhang the tubes 1, in the furnace and prevent
accumulation of ashes behind and around the said tubes, exposing only the sides of
the latter that are in direct contact with the moving fuel. 3, 3, are sleeves that
support the fire brick of the bridge wall K, at those portions which the tubes 1,
intersect, and the latter are thereby left free to their movements of lineal expansion
without rupture to the wall.
al
Land M, are overhanging radiating blocks composed of fire brick, and these
being placed at an angle to the fire are adapted to absorb and radiate the heat, so
as to intensify the temperature of the furnace. The radiating surface L is by its
inclined position adapted to receive the heat from the body of the fire, assuming
glowing temperature, and to transmit the same to the fresh fuel beneath it with
sufficient intensity to ignite the same at an earlier period than would be the
case should the direct heat of the fire be employed to ignite the incoming fuel.
The chain grate N, is composed of interlocking links having any well known or
suitable form of construction, and it is operated over sprocket wheels 4, 5, in the
usual manner, the power being applied to the shaft 6, of the wheels 4. The chain
grate travels over supporting rollers 7, that extend at suitable intervals beneath
the links between the, side frames 8, 8, that carry the sprocket wheel shafts and
form a carriage for the grate and its operating mechanism. The carriage 8, is
provided with truck wheels 9, that fit a flanged track upon which the grate may be
rolled out bodily from the interior of the furnace.
The upper edges of the side frames 8, 8, are inwardly flanged as shewn in
Figure 2, to close the spaces that would otherwise be left at the sides of the grate
links upon which-the-fire-rests,-and there are plates 10, built into the side walls,
overhanging the flanges 11, of the frame 8, adjacent to them and above-which-the
tubes I, are located. The plates 10, being parallel with the flanges 11, effectually
close the sides of the furnace from the spaces exterior to the side frames 8, and 1
here remark that the inclined position of the plates 10 and of the flanges 11,
permit their surfaces to be brought closely together when the grate truck is pushed
back affording a practically tight joint throughout the adjacent surface.
The rear sprocket wheel shaft 12, as more fully appears in Fig. 6, is furnished
with a cylinder 13, enveloping it and extending between the sprocket wheels so as
to fill the spaces as far as possible that would otherwise permit passage of cold air
into the furnace at the reversing point of the grate. The spaces exterior to the
frames 8, adjacent to the side walls and opposite the sprocket wheels 5, are also
filled by flanged caps 18, that abut against the counter surfaces (20, Fig. 7)
of the bridge wall, and have recesses 19, that enclose the hubs of the sprocket.
wheels.
Below the grate truck, I employ one or more ashpan trucks 14, (two being
shewn) that are withdrawn upon suitable tracks beneath and between the tracks of
the grate. There is a partition plate 15, that depends from the caps 18, of the
grate frame between the lower or returning links of the grate and the top of the
ash pan 14, and there is also a partition 16, beneath in the ashpan that corresponds
in position with the plate 15, when the ash truck is in place. A separation is
thereby formed between the body of the ash pit and the chamber 17, to prevent
passage of draft, and the ashes are precipitated into the chamber 17, as the grate

page_text: revolves; the perfectly consumed residue being received in a separate compartment..
from that of the imperfectly consumed coals that form a considerable percentage of
the ash dropping at intermediate points from the fire.
P, is the feeding hopper that is provided at its neck with a feeding and crushing
device 21. The casing 22, of the feeder forms the crown of the furnace door casing
and the furnace doors F, swing on a fulcrum at 23, Figs. 1, 3 and 5. The doors
are fixed to the shaft 24 having a suitable hand lever at the side by which the doors
are raised, and the weight of the doors is counterbalanced by a weight 29, connected
by a chain to the lever 28; the latter having a position relative to the draft of the
weight whereby the doors are held in either their open or closed position by the
gravity of the weight. Access is therefore obtained to the fire independently of
the feeding device and without the necessity of removing any of the parts pertaining
thereto, as has been the case with the forms of mechanisın used heretofore. The
interior of the casing 22, is cylindrical and the feeder 21, rotates therein in the
direction of the arrow Fig. 4. The feeder is composed of blades that form
pockets 25, which fill from the hopper by the gravitation of the coal into them..
Such lumps of the coal as may be larger than the intended size are caught between
the edges of the blades and the adjacent edges of the casing 22, and broken and the
portions are successively discharged or showered upon the grate as the pockets
come opposite the opening 26. It is to be observed that the neck of the hopper
and the opening 26, are sufficiently apart with relation to the blades of the feeder
to cut off ingress of air at all positions of the feeder. The blades moreover, are
arranged spirally as shewn in Fig. 4 whereby their rotation in the direction of the
arrow will tend to spread the fuel toward the sides of the furnace, since the bulk
would naturally tend to pass through the centre of the hopper. The spiral form is
however made of sufficient pitch to more than equalize the said tendency, inasmuch
as it is desired to apportion the coal largely in the side of the furnace for the pur-
poses herein before stated.
The rotation is imparted to the grate shaft 6, and also to the feeder 21, by
mechanism substantially alike. The said mechanism consists in each case of a worm
gear 30 having the teeth on the side of its periphery, a worm 31, engaging there-
with; a ratchet wheel 32, on the worm shaft; and a rock arm 33, fulcrumed on said
shaft, bearing a pawl that engages with a greater or less number of teeth of the
ratchet according to the length of stroke given to the rock arm. The actuating
stroke is derived from any suitable source of given speed as the eccentrics 34 and
said stroke is varied by the adjustment of the eccentric rods 35 at greater or less
distance from the fulcrum of the lever 33. The relative automatic speeds of the
feeder and the grate are thereby varied according to requirements of the fire.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, as communicated to
me, I declare that what I claim is :-
1. The combination with a chain stoker, of a furnace, the side walls whereof
converge in the direction of motion of the grate, whereby the fuel is concentrated
during its passage and combustion.
2. The combination with a boiler furnace, and a chain stoker, of water circulating
pipes extending longitudinally at the sides of the furnace adjacent the surface of the
grate, to form portions of the side walls for retaining the fuel, said pipes connecting
at their respective ends with a lower portion of the boiler and with an upper portion
thereof, to promote circulation substantially as described.
3. The combination with a chain stoker of water circulating pipes extending
longitudinally and adjacent to the furnace walls at or near the surface of the grate,
said pipes converging toward the direction of the lineal movement of the grate for
the purposes specified.
4. The combination with a boiler furnace, and a chain stoker, of the water
boxes E, forming side walls of the fuel receiving chamber, water circulating pipes
extending longitudinally and adjacent the furnace walls and the surface of the

page_text: grate, and connected to a rear and lower. portion of the boiler, and uptake pipe
as H, connecting with a front and upper portion of the boiler, adapted for the pur-
poses specified.
.
5. The combination of a furnace and a removable chain grate frame therein, the
adjacent surfaces whereof form joints inclined with reference to the direction
in which the grate is inserted or withdrawn from the furnace for the purpose set
forth.
6. In a chain grate, the combination of the side frames composing a grate truck
inclined at the upper edges toward the rear of the furnace and surfaces as the
plates 10, that incline correspondingly to the upper edges of the side frames and
project from the furnace side walls to form a joint that is closed by the backward
movement of the grate truck as described.
7. The combination with a chain stoker wherein a space is left as the reversing
point of the links adjacent the bridge wall, of an ash pan adapted to receive the
deposits from intermediate portions of the grate, and having a partitioned com-
partment beneath said reversing point of the links to receive the ashes precipitated
adjacent the bridge wall.
8. The combination with a chain stoker wherein a space is left at the reversing
point of the links adjacent the bridge wall, of a partition plate located vertically
beneath the reversing point of the links, an ash pan extending beneath the grate
and beneath the said space, and a partition plate within the ash pan adapted to
form a continuation of the first named partition plate when the grate and the ash
pan are in place, substantially as and for the purposes specified.
9. The combination in a chain stoker with the sprocket wheels and shaft a the
reversing point of the links, of cylinders enveloping the said shaft at the exposed
spaces of the same between the sprocket wheels, said cylinders having a diameter
whereby they occupy the spaces intervening between the shaft and the inner surfaces
of the links, adapted for the purposes specified.
Dated this Twenty-third day of November 1890.
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.

page_text: Date of Application, 24th Jec., 1890-Accepted, 2nd May, 1891
COMPLETE SPECIFICATION.
[Communicated from abroad by NATHANIEL WATERMAN PRATT and THE
BABCOCK AND WILCOX COMPANY, of New York, in the United States of
America.]
Improvements in Fuel Crushing and Feeding Devices for Rotary
Grate Furnaces.
I, WALLACE FAIRWEATHER, C.E., of 62 Saint Vincent Street in the City of
Glasgow, Registered Patent Agent and Fellow of the Institute of Patent Agents
do hereby declare the nature of this invention and in what manner the same is to
be performed, as communicated to me to be particularly described and ascertained
in and by the following statement :-
This invention is applicable to rotary grates wherein it is essential to apportion
the coal or other fuel in variable quantities upon the different circumferences of the
grate surface.
The invention consists of a combined crusher and feeder rotative upon an axis
located in a vertical plane coincident with a radius of the rotary grate; the spiral
blades of the crusher being inclined with reference to the direction of its rotation
whereby to apportion the fuel chiefly toward the outer circumference of the grate
surface.
Referring to the drawings
Figure 1 is a longitudinal sectional elevation of a furnace having a rotary grate
and to which the application of the crusher and feeder is illustrated.
Figure 2 is a front elevation of Figure 1 and
Figure 3 is an enlarged vertical cross-section showing a portion of the hopper and
the crusher therein.
The revolving grate is composed of sections which are designated by 1, 1, Figure 1,
and the revolving frame supporting the bars or sections is designated by 2, 2; such
frame rotating upon wheels 3. Upon a circular track 4, 5, is a central pier between
which and the circular walls 6, a pathway is formed for the fuel,
7 is a dome or crown of the furnace and 8, an opening therein through which the
fire issues to the space to be heated such as that beneath a tubular boiler 9. 10 is
an opening through which the fuel is supplied, the combustion taking place at one
side of the orbit of the grate beneath the opening 8. 11 indicates a portion of a
radial bridge (the same being broken away) which separates the incoming fuel from
the consumed part thereof that has completed the circuit.
The outer circumference of the grate requires to be supplied with the major
portion of the fuel owing to its excess of surface, and also for the purpose of sealing
the space between the upturned flanges 12, of the grate and the adjacent wall 6, it
becomes important to bank the coal chiefly toward the outer portion of the grate.
To accomplish this the present invention is especially adapted, and it consists as
follows:
39 is a hopper in which the coal is supplied, and 41 the crushing and feeding
device having its axis of rotation located in a vertical plane coincident with a radius
of the circular grate 1. 45, is the cylindrical case partly enveloping the crusher
and feeder and forming the neck of the hopper. The blades 41 of the crusher and
feeder form pockets 60, which are filled from the hopper by gravitation of the fuel
into them as the blades rotate in the direction indicated by arrows. Such lumps of
coal as may be larger than the intended size are caught between the edges of the
blades 41, and the adjacent rigid edges 40, of the casing 45, and broken, being
measured out in given quantities at every revolution and showered through the
opening 10, in the brick work, down upon the grate. The sides of the cylindric
case 45, enclose the pockets 60, as shewn in Figure 3 while the same pass through
Pain 27

page_text: an intermediate position between the upper opening at the throat of the hopper
and the lower opening 10, thereby excluding undue draughts of air above the
grate.
Owing to the helical form of the crusher the work is equalized at every point of
rotation, and the fuel is fed continuously and evenly distributed at each given
circumference of the grate. As indicated at Fig. 1, the spiral inclination of the
blades, and their direction of rotation with reference to such inclination tends to
move the bulk of the fuel outwardly from the portion of the crusher above the
smaller circumference of the grate to that above the larger. The opening 10, is
also diverged in increasing breadth toward its outer portion as indicated in Fig. 2,
providing for the passage of the bulk of the fuel, so disposed.
The speed of the feeder may be made variable with reference to the speed of the
grate to suit the requirements of the fire. To this purpose, suitable automatic
actuating devices may be employed for each.
The crusher and feeder is revolved by the worm gear 42, keyed to its shaft,
and the worm 43, upon the countershaft, engages with it; said countershaft bearing
also a ratchet wheel 45* that is operated by the pawl 46, on the lever 48, connected
at adjustable distances from its fulcrum with the reciprocating operating rod 47,
which receives its motion from an eccentric or other suitable device.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me, I
declare that what I claim is :-
The combination with a rotary grate, of a helical crusher and feeder above the
same, having its axis of rotation located in a vertical plane coincident or nearly so
with a radius of the grate, and having its blades inclined with reference to its
direction of rotation whereby to move and distribute the bulk of the fuel toward
the outer or greater circumference of the grate substantially as described.
Dated this Twenty-third day of November 1890.
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.