Improvements in and connected with Furnaces for Steam Generators and for other purposes.
Year: 1892

page_text: Date of Application, 9th Aug., 1892-Accepted, 10th Sept., 1892
COMPLETE SPECIFICATION.
Improvements in and connected with Furnaces for Steam Generators
and for other purposes.
1 ALFRED WILKINSON of Bridgeport in the County of Montgomery State of
Pennsylvania United States of America Mechanical Engineer 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 the construction of the grates for steam boiler and other
furnaces and also to means for governing the operation of steam boiler furnaces-so
as to insure the maintenance of a substantially uniform pre-determined pressure in
the boiler.
The grate is especially designed for effecting the through combustion of fine coal
or culm, although it is capable of general use. I will describe the invention with
reference to the accompanying drawing
--
Figure 1 of which is a longitudinal section of a sufficient portion of a steam boiler
furnace to illustrate the invention;
Figure 2 is a part plan and part horizontal section on the line 1-2 Figure 1;
Figure 3 is a sectional view illustrating a modified form of ash discharger;
Figures 4 and 5 are enlarged views of a device forming part of the invention and
intended for operating the ash discharging section of the improved grate;
Figure 6 is a front view of a series of boilers and their furnaces, illustrating the
means employed for governing the operation of the said furnaces; and
Figure 7 is an enlarged view of a regulating valve forming part of the furnace
governing mechanism.
In Figure 1A represents part of the masonry of a steam boiler furnace, and
B the front plate of the same. Upon the upper portion of this plate is a hopper a for
containing the fuel, this hopper having (in the lower portion in the present instance)
a vaned wheel a' intended to be rotated in the direction of the arrow by any of the
usual forms of mechanism adopted for the purpose, although such feed wheel need
not be used in all cases.
Projecting from the front plate of the furnace below the hopper are two hollow
bearing blocks or brackets D and F which form bearings for the upper ends of the
grate bars G, each of these grate bars being hollow and being inclined throughout
the greater portion of its length at an angle corresponding to the natural angle of
repose of a mass of granular material, the upper portion of each bar, however, being
horizontal so as to fit between and be supported by the brackets D and F, some of
the bars being also free to move forward and backward between the brackets, as
explained hereafter.
The lower portion of each grate bar is turned downward so as to form a vertical
foot resting upon a hollow transverse beam or girder H suitably mounted in the
masonry of the furnace, the lower ends of the grate bars and the upper face of the
said beam or girder forming a reasonably tight fit.
From the front of the hollow girder H projects a pipe I which is open at the
front end and is provided with a steam blast or injector nozzle b whereby a flow of
air and steam is caused to pass through the pipe I into the hollow girder H.
In the upper portion of the hollow girder Hare formed ports d and in the bottom
of the grate bars G are formed like ports f so that the air forced into the hollow
girder has free access to each of the hollow grate bare.
The inclined portion of each of the hollow grate bars is stepped, as shewn in
Figure 1, and in the front of each of these steps is formed a tuyere like opening i,
through which a stream or jet of air is injected into and through the mass of fuel

page_text: resting upon the grate bars, these jets being thus distributed throughout the mass
of fuel so as to insure effective combustion thereof.
A space or well J is formed between the bridge wall of the furnace and the
hollow girder H and downwardly extended portions of the foot of the grate as
shown in Figure 1, and jets of air are projected into this well through openings in
a perforated plate g which is adapted to the slotted front of the hollow girder H as
shown in Figure 1, so that any fuel which escapes combustion in its passage
downward over the grate bars G is exposed to these air currents in the well J and
combustion of the same is thereby insured.
The bottom of the well J is closed by a rotating ash discharger K consisting in
the present instance, of a series of discs m secured to a hollow shaft M which is
adapted to turn in suitable bearings in the side walls of the furnace and projects
beyond one of said side walls for the application of power whereby it can be
rotated.
Each disc m has side lugs or distance pieces n whereby the discs are separated to
the desired extent, and in each disc are formed recesses s, (segmental in the present
instance, although they may be of any desired form) which recesses are successively
brought under the well J by the rotation of the ash discharger and form longitudinal
troughs or channels for receiving the ashes and conveying the same forward in the
direction of the arrow Figure 1, so as to dump them into the ash pit, the adjacent
face of the girder H being preferably concaved so as to permit the discs m to work
in close proximity thereto.
Although in most cases it is preferred to use the rotary ash discharger consisting
of a number of discs strung on a shaft in the manner described, other forms of
rotary discharger may be used without departing from the nature of the invention,
for instance in Figure 3 is shown one consisting of a hollow cylinder, having
recesses s in its opposite sides, the said cylinder having if desired hollow trunnions
so that a circulation of steam or air through the cylinder may be maintained for
the purpose of keeping the same cool.
Some of the grate bars G, for instance, those marked with a star in Figure 2, are
stationary, but the alternate grate bars are movable to and fro on their bearings on
the hollow girder H and bracket F such to and fro movement being imparted to
the said grate bars from a crank shaft N which is mounted in suitable bearings
depending from the bracket F, and slowly rotated by any suitable means, as for
instance, by means of a sprocket wheel receiving a chain belt adapted to a sprocket
wheel on the shaft of the distributer a¹ of the fuel hopper as shown by dotted lines
in Figure 1.
The shaft N has one crank for each of the moveable grate bars G, the crank pin
being embraced by the outer end of a link p the inner end of which is connected to
a pin p' carried by a stud or lugs on the underside of the grate bar.
The forked outer end of the link p which embraces the pin of the crank shaft N
is provided with a follower t adjustable by means of a set screw t¹ so as to provide
either a snug fit upon the crank pin or for permitting any desired amount of lost
motion in order to regulate the extent of reciprocation of the moveable grate
bars.
The rotating shaft of the discharger K may if desired be driven by a belt
adapted to sprocket wheels on the shaft M of the said ash discharger, and on the
crank shaft N as shown for instance by dotted lines in Figure 1, but in cases in
which this method of driving is not available the said ash discharger may be
rotated by means of ratchet lever mechanism such as shown in Figures 4 and 5, in
which figures P represents a ratchet wheel secured to the shaft M of the ash dis-
charger, and S S represent a pair of levers loosely hung to the said shaft and
carrying between them a weighted pawl w for engagement with the teeth of the
ratchet wheel, as shown in Figure 4.
The upper portions of the levers S are connected by transverse pins x which form
a socket for the reception of the butt ¹ of the operating handle T whereby the
levers may be conveniently vibrated so as to rotate the ash discharger by a series

page_text: of intermittent movements, a transverse pin y being used if desired to prevent the
accidental withdrawal of the handle from engagement with the levers.
It is preferred to use the steam jet or injector b as a means of causing inflow of
air through the pipe I, but other forms of blast mechanism may be substituted
for the steam jet if desired, or with some fuels, natural draught may be relied
upon.
When steam is mixed with the air, however, it serves to keep the grate bars cool
and thereby prevents warping or other distortion of said bars. The fuel supporting
faces of the grate bars need not in all cases be stepped although it is considered to
be the preferable plan, as the tuyere openings are then not so likely to be clogged
up by the fine portions of the fuel.
The means for regulating the operation of the furnace, so as to maintain a
uniform or substantially uniform pressure in the boiler in connection with which the
furnace is used is shown in Figures 6 and 7.
In Figure 6, is represented a series of four boilers, which are provided with
automatic stokers, and with furnace grates of the character before described,
although it should be understood that the invention is applicable to any furnace
having an automatic stoker, or draught apparatus operated by a steam blast, and
also to single furnaces as well as to multiple furnaces.
In the drawing a represents the hoppers of the series of automatic stokers, a' the
shaft which carries the feed wheels in the said hoppers, N the shaft which carries
the grate bar operating devices, I the air pipe in the ash pit of the furnace, and
61 the pipe for supplying steam, to the injector head b, in the said air pipe, the air
from the latter pipe being delivered into the hollow bars of the grate. This part
of the invention is also applicable to furnaces having an ash pit blast operated by a
steam jet, or to furnaces in which a steam jet is located in the up-take for the
purpose of increasing the draught.
The shafts a' and N are, in the present instance connected for joint operation,
and the shaft a¹ is driven by an engine W, which receives steam through a pipe k
from a main h, the latter having also branch pipes h¹ from which extend valved
branches 0, for supplying the injector pipes b¹.
The main his connected to the main n which communicates with the steam domes
of the stack of boilers, and in the said main his located a governing or regulating
valve X as illustrated in Fig. 7 of the drawing.
That chamber of the valve communicates with the main steam pipe of the
boilers, and is separated from the chamber ', communicating with the main h, by
means of a cross partition q which carries a cylinder q' with two sets of ports, 1,
the ports being located in the chamber of the valve, and the ports r¹ in the
opposite chamber z¹.
32
Fitting snugly in the ported cylindrical chest q' is a cylindrical valve R closed
at both ends, but having ports similar to the ports rr, the said valve R
having a depending stem R¹ which passes through a stuffing box at the bottom
of the valve casing, and carries a series of weights R³, as shewn in Figure 6, the
valve casing being suspended by a rod R3, from a ceiling joist or other suitable
support, so that the weight of the valve and its appurtenances does not exert any
strain upon the pipe h.
The normal position of the valve R is about that represented in Figure 7 of
the drawing, on reference to which it will be observed that the ports of the
valve only partially uncover the ports of the cylinder q'.
When the normal or predetermined pressure of steam is maintained in the
boiler, the pressure beneath the valve R counterbalances the pressure above the
same, plus the downward influence exerted by the weight R and the valve is
maintained in the position shewn in Figure 7, the flow of steam through the
valve in this case being sufficient to run the engine Wat a rate of speed
sufficient to effect the normal operation of the stokers and to provide for the
normal operation of the injectors in the blast pipes which govern the draft. If
there should, however, be any decrease in the pressure in the boiler main u there

page_text: will be a downward movement of the valve R and a further opening of the
ports so as to provide for an increased flow of steam to the engine and
injectors, with consequent quickening of the feed of the stokers, and augmenting
of the blast in the draft apparatus, while, on the other hand, should the pressure
in the boilers rise above the normal, there will be a raising of the valve R, and
a further closing of the ports, thus limiting the flow of steam through the
valve with the effect of decreasing the speed of the engine, lessening the feed of the
stokers and decreasing the force of the blast in the draft apparatus, in other
words, the tendency on the lowering of pressure in the boiler is to quicken the
fire in the furnace, and on the raising of pressure in the boiler to restrain the fire,
so that the action of the furnace is directly dependent upon the pressure in
the boiler and the fires are so regulated as to maintain the said pressure practically
-uniform.
Although it is preferred in carrying out this invention, to provide the
cylinder 9' and valve R with ports both at top and bottom, in order to insure
the desired accuracy in the operation of the valve, yet a reasonably accurate
valve could be made even if one or other of the sets of ports were dispensed
with. For instance the valve may be constructed with the lower set of ports only
and may be open at the top, or on the other hand, the cylinder q' and valve R,
may be ported at the top only, the valve being open at the bottom, with the
exception of an open frame or spider for the connection of the stem R¹ or the
ported valve may be used in connection with a cylinder 9' having straight edges
instead of ports.
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 :-
First. A grate for furnaces, consisting of hollow inclined bars, each of which
has a series of tuyere openings in the inclined fuel supporting face of the bar,
and means for supplying air to the said hollow grate bars, substantially as
hereinbefore described.
Second. A grate for furnaces consisting of a series of hollow inclined bars,
in combination with means for supplying air to the said bars, each of the bars
being stepped on the fuel supporting face, and the said steps having in the
fronts of the same tuyere openings for the discharge of air into the bed of the
fuel, substantially as hereinbefore described.
Third. A grate for furnaces, consisting of a series of hollow inclined bars, some
of which are movable to and fro past the others, the bars having tuyere openings
in their fuel supporting faces in combination with means for supporting the grate
bars at top and bottom, means for moving the moveable bars of the grate, and
means for forcing air into the bars, substantially as herein before described.
Fourth. The combination in a grate for furnaces, of hollow inclined grate bars
having tuyere openings in their fuel supporting faces, a hollow transverse beam or
girder supporting the said bars, and communicating with the interiors of the same,
and means for forcing air into the said hollow beam or girder, substantially as
hereinbefore described.
Fifth. The combination in a grate for furnaces, of hollow inclined grate bara
having tuyere openings in their fuel supporting faces, a hollow transverse beam or
girder supporting the said bars and communicating with the interiors of the same,
an air inlet pipe communicating with the said hollow beam or girder, and a steam
jet or injector for causing a flow of air and steam into and through the said pipe
and into the girder, substantially as hereinbefore described.
Sixth. The combination in a grate for furnaces, of hollow inclined grate bars
having tuyere openings in their fuel supporting faces, a hollow beam or girder
serving as a support for the said bars, and communicating with the interiors of the
same, means for forcing air into the said hollow beam or girder, and a perforated
air distributer in front of the said girder, substantially as hereinbefore described.

page_text: Seventh. The combination in a grate for furnaces, of inclined grate bars, with
a rotary ash discharger, at the bases of the said bars, substantially as hereinbefore
described.
Eighth. The combination in a grate for furnaces of inclined grate bars, with a
rotary ash discharger at the base of the grate, the said ash discharger comprising
a series of recessed discs mounted side by side upon a shaft, whereby the parallel
recesses of the series of discs form an ash receiving chamber, substantially as
hereinbefore described.
.
Ninth. The combination in a grate for furnaces, of inclined grate bars, with a
rotary ash discharger at the base of the grate, the said ash discharger consisting of
a series of discs mounted upon a shaft and each having laterally projecting lugs
for bearing upon the adjacent disc, each disc also having one or more recesses
for receiving, conveying and discharging the ashes, substantially as hereinbefore
described.
Tenth. The combination in a grate for furnaces, of inclined grate bars with the
rotary ash discharger at the base of the grate, the said ash discharger consisting of
a series of recessed discs mounted upon a shaft having a projecting end provided
with a ratchet wheel and a loosely swinging lever or levers carrying a pawl for
engagement with the said ratchet wheel, substantially as herein before described.
Eleventh. The combination in furnaces for steam boilers, of a mechanical stoker,
a motor for operating the same, a pipe for conveying steam from the boiler to said
motor, and an automatic regulating valve in said pipe opening against the pressure
in the boiler, substantially as herein before described.
Twelfth. The combination in steam boiler furnaces, of draft apparatus operated
by an injector, a pipe for conveying steam from the boiler to the said injector, and
an automatic regulating valve in said pipe opening against the pressure in the
boiler, substantially as hereinbefore described.
Thirteenth. The combination in a steam boiler furnace, of a mechanical stoker,
a motor for driving the same, draft apparatus operated by an injector, a pipe for
conveying steam to said motor and injector, and an automatic regulating valve in
said pipe, opening against the pressure in the boiler, substantially as herein before
described.
Fourteenth. The combination of the valve casing, its fixed cylinder and moving
valve, one or both ported as described, said valve being acted on by the boiler
pressure to close the ports, and by pressure in the delivery pipe to open the ports,
substantially as hereinbefore described.
Fifteenth. The combination of the valve casing, its fixed cylinder and the
movable valve, one or both ported as described, said valve having a projecting
weighted stem, and being actuated by boiler pressure to close the ports, and by
pressure in the delivery pipe added to the weight upon the stem to open the ports,
substantially as hereinbefore described.
Sixteenth. The combination of the valve casing having the valve with depending
weighted stem, and a suspending rod for supporting said valve, whereby the pipe
with which the valve is connected is relieved from the strain due to the weight of
the valve and its appurtenances, substantially as hereinbefore described.
Dated this 9th day of August 1892.
J. H. JOHNSON & Co.,
Agents.