Improvements in Mechanical Furnaces or Grates.
Year: 1894

page_text: PROVISIONAL SPECIFICATION.
Improvements in Mechanical Furnaces or Grates.
We CHRISTOPHER WILLIAM JAMES of South View Potternewton Lane
Engineer and GEORGE WATSON of 2 Woodsley Terrace Engineer both in the
City of Leeds do hereby declare the nature of this invention to be as follows:-
:-
Our invention is for improvements in what have been heretofore described as
mechanical furnaces or grates but is applicable to externally as well as internally
fired boilers to evaporators and to refuse and other furnaces. And our invention
relates more particularly to that class of furnace in which the travelling grate bars
are set transversely in the furnace.
In carrying out our invention so far as relates to furnaces we employ the grate
bars themselves without addition of any kind as fuel bearers or carriers and we
make use of a sufficient number to form when placed side by side a continuous grate
but we employ no endless chain as carrier nor are the grate bars coupled or tied
together in any way.
The grate bars are mounted upon suitable side frames and are actuated by any
suitable driving gear placed at or near one end of the furnace and operating in such
manner that each grate bar after it leaves the driving gear pushed forwards by
the grate bar immediately following it and so caused to traverse the complete
circuit that is to say the whole length of the furnace and back to the driving gear
to be again sent forward.
The grate bars are carried at the end on balls or rollers travelling in suitable
guides in the sides of the supporting frames. When balls are employed the ends
of the grate bars are grooved longitudinally in suitable shape to the depth of
about one half the diameter of the balls but the groove is to be slightly greater
than the diameter of the balls to enable the grate bars to travel freely on the
balls. A similar groove is formed in the sides of the supporting frame. This
groove extends from front to back of the furnace and back again bending round
at each end and is endless. When the grate bars are in position the balls employed
will be partly within the groove in the side frame and partly within the groove in
the ends of the grate bars so that the latter will ride freely on the balls with but
very little friction whilst the balls themselves are held in position by the bars.
When rollers are employed the rollers will be mounted ou axles formed on or
connected to the ends of the grate bars in such a manner and will be of such a size
as not to come into contact with each other but ride upon the paths prepared for
them. In either case that is to say whether balls or rollers be employed the paths
or guides formed in the sides of the frame to receive them may be and preferably
are perforated in such a manner that currents of air may be forced or induced to
pass through the perforations thus blowing away dust or other obstructions from
off the balls or roller paths without interfering with the free movement of the balls
or rollers and at the same time assisting the fire as well as tending to keep the
frame sides cool. When the travelling grate is employed in a boiler. flue the space
between the flue and the side of the grate bar frame may be used as an air way.

page_text: In other cases an air space may be constructed in the side of the furnace or in the
grate bar frames and preferably may be formed of a hollow iron casing or pipe.
The mechanism for actuating the grate bars may consist of toothed wheels driven
at a suitable speed and placed either inside or outside the endless band of grate
bars or of a worm or screw gearing into the grate hars or of the reciprocating or
intermittant motion of a pusher pawl or ratchet or of a chain with projections fitting
into or between the grate bars and having sufficient contact with them preferably
at a point outside of the furnace to cause them to go forward.
At the front or feeding end of the furnace we provide a hopper for the fuel in
connection with which is a pusher working horizontally at or near the bottom and
automatically driven for feeding or delivering the fuel on to the grate bars. The
pusher is preferably arranged so that the length of stroke may be varied so as to
deliver less or more fuel as may be required on to the grate bars. It is connected
with the same driving gear as the grate bars and in this way the supply of fuel is
proportioned to the rate of movement of the grate bars and to the thickness of fire
required. But any other know means may be employed for delivering fuel on to
the grate.
We place the feeding apparatus preferably at a sufficient height above the grate
to allow of a convenient fire door being placed in front of the furnace to permit of
stirring the fire by hand or of stoking by hand when desired and also to allow of
the withdrawal of any or all of the grate bars from the furnace. And preferably
we provide fire brick linings to the feeding end of the furnace (whether front or
otherwise) extending some distance into the furnace. We also sometimes protect
the side frames by fire brick quarries from exposure to fierce heat.
The removal of any grate bar is further provided for by making a portion of the
side or top or bottom of the ball or roller path or guide detachable so that any
grate bar together with the balls or rollers on which it is resting may be readily
lifted out. The grate bars and other mechanism are preferably so arranged that
the furnace can be worked with a closed front as well below as above the grate bars
and with forced draught but provision is made either at the front or side or back of
the furnace for clearing away the ashes.
When forced draught is used we prefer to introduce it through the sides of the
grate bar frame and into the space between the going and returning grate bars.
At the inner end of the furnace and between the end of the continuous grate
and the bridge or between some point near the end of the continuous grate and the
bridge but mounted in the same frame as the grate bars or mounted independently
thereof we use a form of tipping apparatus or else a trap door so arranged that
the ashes or clinker can fall off the grate bars at the far end of the furnace into
the ash pit without admitting a large inrush of air past the end of the continuous
grate or reducing the pressure below the grate bars. And the grate bar frame is
of such length and so constructed as to extend back close to the wall of the bridge
for the like purpose. The bridge is preferably built detached from the grate bar
frame and is preferably an overhanging bridge of fire brick.
When applied to internally fired boilers the whole grate mechanism including the
frames grate bars gearing hopper and tipping apparatus or trap door is preferably
supported upon wheels in such a manner that it can be moved into or out of position
at will. This arrangement is not new but in front of the furnace we now provide a
step in the form of an inclined plane to prevent any sudden drop on withdrawing
the mechanism from the flue as well as to assist in getting it into the flue.
A separate mechanism will be employed for each flue except that one driving
shaft may be common to two or more sets of mechanism and to guard against any
difficulty arising from imperfect alignment between two or more flues we break the
driving shaft between the different sets of mechanism and introduce flexible
couplings preferably consisting of coils of steel bolter or otherwise fixed on the
ends of the shaft.
In some cases jets of steam or water troughs into which the grate bars may be
made to dip during some portion or the whole of their backward journey may be

page_text: found of assistance in keeping the whole mechanism cool and thus preserving its
efficiency.
Dated this 19th day of December 1894.
We CHRISTOPHER WILLIAM JAMES of South View Potternewton Lane
Engineer and GEORGE WATSON formerly of 2 Woodsley Terrace but now of
21 Springfield Mount Engineer both in the City of Leeds, 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 :-
Our invention relates to improvements in what have been heretofore described
as mechanical furnaces or grates but it is applicable to externally as well as
internally fired boilers, to evaporators and to refuse and other furnaces, and our
invention relates more particularly to that class of furnaces in which the travelling
grate bars are set transversely in the furnace.
In carrying out our invention we employ the grate bars themselves without
addition of any kind as fuel bearers or carriers and we make use of a sufficient
number to form when placed side by side a continuous grate but we employ no
endless chain or carrier nor are the grate bars coupled or tied together in any way.
The grate bars are carried by suitable side frames and are actuated by any
suitable driving gear placed at or near one end of the furnace and preferably
operating in such manner that each grate bar after it leaves the driving gear is
pushed forwards by the grate bar immediately following it and so caused to
traverse the complete circuit that is to say the whole length of the furnace and
back to the driving gear to be again sent forward.
The grate bars are carried at their ends on balls or rollers travelling in or upon
suitable guides in the sides of the supporting frame. When balls are employed
the ends of the grate bars are grooved longitudinally in suitable shape to the depth
of about one half the diameter of the balls but the groove is to be slightly wider
than the diameter of the balls to enable the grate bars to travel freely on the
latter. A similar groove is formed in the sides of the supporting frame. This
groove extends from front to back of the furnace and back again bending round at
each end and is endless. When the grate bars are in position the balls employed
are partly within the groove in the side frame and partly within the grooves in the
ends of the grate bars so that the latter ride freely on the balls with but very little
friction whilst the balls themselves are held in position by the bars. When rollers
are to be employed they are to be mounted on axles formed on or connected to the
ends of the grate bars in such a manner and of such a size as not to come into
contact with each other but ride upon the paths prepared for them. In either case
that to say whether balls or antifriction rollers be employed the paths or guides
formed in or on the sides of the frame to receive them may be and preferably are
perforated in such a manner that currents of air may be forced or induced to pass
through the perforations thus blowing away dust or other obstructions from off the
balls or roller paths without interfering with the free movement of the balls or
rollers and at the same time assisting the fire as well as tending to keep the
frame sides cool and the balls or rollers from excessive heat. When the travelling
grate is used in a boiler tube or flue the spaces between the flue and the sides
of the grate bar frames may be used as an airway, In other cases an air space

page_text: may be constructed in the side of the furnace or in the grate bar frame and
preferably may be formed of a hollow iron casing or pipe.
At the front or feeding end of the furnace we preferably provide a hopper
furnished with a pusher for feeding or delivering the fuel on to the grate bars.
But any other known means may be employed for that purpose.
We place the feeding apparatus at a sufficient height above the grate to allow
of a convenient fire door being placed in front of the furnace to permit of stirring
the fire by band or of stoking by hand when desired and also to allow of the
withdrawal of all or any of the grate bars from the furnace-and preferably we
provide fire brick linings for the feeding end of the furnace (whether front or
otherwise) extending some distance into the furnace. We also sometimes protect
the side frames by firebrick quarries from exposure to fierce heat.
The removal of any grate bar is further provided for by making a portion of the
side or top or bottom of the ball or roller path or guide detachable so that any
grate bar together with the balls or rollers on which it is resting may be readily
lifted.
The grate bars and other mechanism are preferably so arranged that the furnace
can be worked with a closed front as well below as above the grate bars and with
forced draught but provision is made either at the front or side or back of the
furnace for clearing away the ashes.
At the inner end of the furnace and between the end of the continuous grate and
the bridge or between some point near the end of the continuous grate and the
bridge but mounted in the same frame as the grate bars or mounted independently
thereof we use a form of tipping apparatus or else a trap door (both common
methods) so arranged that the ashes can fall off the grate bars at the far end of
the furnace into the ashpit without admitting a large inrush of air past the end of
the continuous grate or reducing the pressure below the grate bars and the grate
bar frame may be of such a length and so constructed as to extend back close
to the wall of the bridge for the like purpose. But instead of or in addition to
such tipping apparatus and for the like purpose we may use a well known device
consisting of a door so arranged as to fill up the space under the grate bars at or
near the back or inner end of the grate and capable of being lifted or opened by
means of a chain or rod extending to the outer or front end of the furnace in order
to remove the ashes and clinker which fall over the end of the grate as the bars,
travel round.
The bridge is preferably built detached from the grate bar frame and is pre-
ferably an overhanging bridge of fire bricks. When applied to internally fired
boilers the whole grate mechanism including the frames, grate bars, gearing hopper
and tipping apparatus or trap door (if used) and doors for removing ashes or
clinker is preferably supported upon wheels in such a manner that it can be moved
into or out of position at will. This arrangement is not new but in front of the
furnace we now provide a step in the form of an inclined plane to prevent any
sudden drop on withdrawing the mechanism from the flue as well as to assist in
getting it into the flue.
In applying this invention to a boiler or a steam generator having two or more
flues as for example in applying it to a Lancashire boiler or to a cylindrical
marine boiler a separate mechanism will be used for each flue except that one
driving shaft may be common to two or more sets of mechanism and to guard
against any difficulty arising from imperfect alignment between two or more flues
we break the driving shaft between the different sets of mechanism and introduce
flexible couplings preferably consisting of coils of steel bolted or otherwise fixed on
to the ends of the shaft. In some cases jets of steam or water troughs into which
the grate bars may be made to dip during some portion or the whole of their
backward journey, may be found of assistance in keeping the whole mechanism cool
and thus preserving its efficiency.
In the accompanying drawings we show our invention applied to the type of
steam generator known as a Cornish boiler having a single flue or furnace tube but

page_text: it will be obvious that our invention is also applicable to boilers having two or
more flues, also to externally fired boilers and to refuse and other furnaces and
evaporators and except as hereinafter mentioned we also show our travelling grate
provided with balls to carry the grate bars.
The exceptions just referred to are contained in Figures 6 and 7 Sheet 5 and
Figures 12 and 13 Sheet 6.
Figure 1 Sheet 1 shows a partial side elevation Figure 2 Sheet 2 a longitudinal
section Figure 3 Sheet 3 a front elevation Figure 4 Sheet 4 a cross section and
Figures 5, 6, 7, 8, 9 and 10 Sheet 5 and Figures 11, 12 and 13 Sheet 6 show
various details more clearly than they can be shown in the more complete views of
our invention applied to such a boiler as aforesaid.
The same letters refer to the same parts in all the drawings.
A. B are the frame sides of the furnace held together at suitable distances apart.
by the bolts 35 (Figure 2). They are provided with endless grooves C.D. to
form paths for the balls G. G and these grooves may be conveniently cast in the
frames, E. E are grate bars of which only a few are shown in position to avoid
complicating the drawings. These grate bars are provided with grooves F, F, in
their ends Figures 4 and 5 and by means of these grooves they rest upon the
balls G. G Figures 2, 4 and 5 both in going and returning. The bars in travelling
round the curves at the ends of the ball paths in the frame sides turn over so that
they go along the upper path with their surfaces for the fuel at the top and come
back along the lower path upside down Figure 2. The balls may be of any
suitable material for example of cast iron and in that case they may be conveniently
cast in a metal mould or chill. The spaces H. I (Figure 4) between the frame sides
.and the inner surface of the boiler flue are utilised for the purpose of blowing in
air as herein before mentioned which escapes by means of the perforations J
Figures 4 and 5 into the ball paths for the purpose of blowing away any dust or
ash which may fall into the ball paths, also to prevent any clinker adhering to the
balls or the bar ends, to keep them from excessive heat and to assist in the
combustion of the fuel upon the grate. The spaces H. I may if preferred be
enclosed as hollow casings attached to the frame sides to prevent escape of air.
The perforations J are preferably placed at suitable intervals along the whole
length of the endless grooves.
The mechanism by which we prefer to actuate the grate bars and cause them to
travel forwards consists of two pawls K see Figure 2 mounted upon the shaft M
also shown in Figures 1 and 3 which engage the bars at or near the curve at the
outer end of the furnace.
The shaft M passes through both pawls and through slots 27 and 28 (Figures 1,
2 and 11) provided in the frame sides to allow of its proper movement and is secured
at its ends to the free ends of the two levers or radius arms N. O which cause it
and therewith the pawls K to oscillate in the arc of a circle. The levers or radius
arms N. O are provided with rollers L Figures 2 and 3 by which they bear upon
and are actuated by the two cams P. Q (see Figure 1) keyed or otherwise fastened
on a shaft R the cams being of such a size and shape as to move the ends of the
levers N.O through a certain distance which may preferably be about or a little
more than the width of one fire bar, so that when the cams operate the levers and
through them the pawls K the whole of the fire bars are driven forward through
the distance aforesaid. When this has been done the cams in the course of their
rotation allow the levers N. O and the pawls K to drop back to the bottom of their
stroke and engage with the next fire bar ready for the above action to be repeated.
The arms or levers N.O are attached to studs S. T Figures 1. 2. 3 and 11. fixed
upon the side frames preferably concentrically with the curve traversed by the fire
bars in passing the end of the frame so that the pawls K follow the same curve as
do the fire bars.
As the speed at which the fire bars and consequently the cams P. Q are required
to move is comparatively slow it is convenient to drive the cam shaft R by some
form of reducing gear and we have shown for this purpose (see Figures 1. 2

page_text: and 3) a ratchet wheel U driven by a ratchet V which ratchet V is attached to a
radius link W and is driven by an eccentric X attached to or forming part of the
speed cone Y.
The feeding gear which we prefer to use consists (see Figures 1. 2 and 3) of a
hopper 1, at the bottom of which is a broad pusher or plunger 2 this plunger is
driven backwards and forwards through a suitable distance and at a suitable speed
to give the requisite rate of feed. The fuel is placed in the hopper 1 and pushed
out at the bottom as required by the action of the plunger 2, when it falls on to
the grate and is carried forward and burned as in other travelling furnaces. The
plunger 2 may be driven by means of connecting rods 3, 4 and levers 5, 6 keyed
or otherwise fastened upon a shaft 7 to which is secured a lever 8 which is in turn
driven by a connecting rod 9 and a lever 10 attached to the cam Q or otherwise
secured to and rotating with the cam shaft R which drives the grate as before
described. The rate of action of the plunger 2 is thus proportioned to the speed
of travel imparted to the grate but the length of stroke of the plunger 2 may be
varied by altering the position of the connecting rod 9 upon the lever 10 which is
provided for that purpose with a slotted hole (see Figure 1) so that the connecting
rod 9 may be clamped to the lever 10 in any desired position within the limits
of the slotted hole and thus the thickness of fire upon the bars may be varied
at will.
Air may be blown or forced into the spaces H. I between the frame sides and
the inner surface of the flue by means of a fan or blowing engine or by one or
more steam jets or other common means if any.
We prefer to make use of steam jets for this purpose and when we do so two
trumpets 11, 12, (see Figures 1 and 3) may be provided attached to the frame
sides a steam jet being preferably placed to blow into each trumpet. We also
prefer to use one or more steam jets for a like purpose when using our travelling
grate with forced draught and in the drawings we have shown the place of
introduction of the blast by the trumpet 13 at one side of the frame. But one
source of air supply may be used both for forcing the fire and for blowing into the
spaces H. I. for the purposes hereinbefore mentioned, for example one or more
steam jets may be placed close together and blowing into one trumpet and the
stream of air be afterwards divided by suitable pipes as required. 14 (Figures 1. 2
and 3) is a door used to close the ashpit when the furnace is being used with forced
draught. It may be opened when required for the removal of ashes and clinker.
15 (Figure 2) is the trap door at the back or inner end of the furnace to prevent
the escape of air while at the same time allowing the clinker to drop over the end
of the grate. It swings upon knife edges 16 resting upon bearers 17 which are
preferably fixed to or forming part of the frame sides A. B but which may be
attached to the bridge or carried otherwise.
The trap door is so balanced that the weight of the clinker will readily cause it
to open downwards and afterwards when the clinker drops off it will return to its
proper position. We have not shown the alternative or additional common method
of a door under the fire bars. 18 is the bridge which we prefer to construct of
fire brick quarries or bricks so disposed as to protect the trap door 15 as far as
possible from the direct action of the flames. 19 is the combustion chamber which
we also prefer to line partly or wholly with fire brick and to provide with a fire
brick arch over the first or outermost portion of the grate to protect the boiler
plates at that part from the intense heat aud to maintain a high temperature for
the ready ignition of fresh fuel and the consumption of smoke. 20 (Figures 1. 2
and 3) is a fire door of good size so that access to the fire may be readily had if
required. For the removal of any or all of the bars when required we provide
two loose pieces 21 and 22 (one on each side) (see Figures 1 and 11) in the frame
sides which may be retained in place by screws or bolts 29 and 30. And the
position in which we prefer to place these loose pieces is that shown clearly in
Figure 11 Sheet 6.
We prefer to carry the whole mechanism including the feeding gear according to

page_text: the common method upon wheels one 23 at the inner end within the flue-and
two 24 and 25 at the outer end resting upon the firing floor see Figures 1. 2. 3
and 4. By these means the whole mechanism can be readily removed from the
flue. But for the purpose herein before mentioned we provide the sloping block 26
Figures 8, 9, 10 Sheet 5. upon which the wheel 23 may be run down when removing
the grate from or run up when replacing it in a boiler tube or flue.
It will be obvious that instead of balls as shown in cross section in Figures 4
and 5 rollers may be used as shown in Figure 6 Sheet 5. It will also be obvious
that instead of grooves in the side frames ribs may be used formed on and projecting
from the frames as shown in Figures 7 Sheet 5 and Figures 12 and 13 Sheet 6 and
that such ribs may be used in combination with rollers as shown in Figures 12 and 13
Sheet 6 or without rollers as shown in Figure 7 Sheet 5. In Figure 6 Sheet 5 the
fire bar E is shown with a roller mounted on an axle and running within a groove
in the side frame A. In Figure 12 Sheet 6 the fire bar E is shown with two
rollers 31 and 32 on the end mounted on axles and running one roller above and
the other below the rib 34 formed on the side frame. In Figure 13 Sheet 6 the
fire bar E is shown provided with a forked end and carrying a hollow pulley or
roller or runner wheel 33 whose axis is in a vertical plane travelling upon the
endless rib 34 of a size and shape to fit into the hollow edge of the pulley or roller
or runaer wheel in such manner that the flange of such pulley or roller or runner
wheel and therewith the fire bar may ride upon and be supported and guided by
such rib. And in Figure 7 Sheet 5 we have shown a method of mounting the fire
bar E upon the endless rib without the use of rollers.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what
we claim is:
1. In mechanical furnaces or grates in which the fire bars are placed transversely
in the furnace and made to travel continuously or intermittently along the length
of the furnace the use of balls running in grooves constructed partly in the side of
the supporting frame and partly in the ends of the fire bars for the purpose and
substantially as hereinbefore and in the drawings described.
2. In such mechanical furnaces as aforesaid the use of rollers mounted upon axles
attached to the ends or forming parts of the travelling fire bars and running in
endless grooves or upon endless ribs constructed in or on the side frames as herein-
before described for the purpose and substantially as hereinbefore and in the
drawings described.
3. In such mechanical furnaces as aforesaid the use of an endless rib or ribs
constructed on each side frame and projecting into the grooved or forked end of
each fire bar as a path upon which the fire bars may ride and be supported without
other support for the purpose and substantially as hereinbefore and in the drawings
described.
4. In such mechanical furnaces as aforesaid the formation of an endless grate or
fuel bearer by the use of fire bars placed side by side transversely to the direction
of travel but not connected with each other mounted and travelling upon balls and
not otherwise supported for the purpose and in the manner substantially as herein-
before and in the drawings described.
5. In such mechanical furnaces as aforesaid the formation of a continuous grate
or fuel bearer by the use of fire bars placed side by side transversely to the direction
of travel but not connected with each other mounted upon rollers travelling in
endless grooves constructed in the side frames but not otherwise supported for the
purpose and in the manner substantially as hereinbefore and in the drawings
described.
6. In such mechanical furnaces as aforesaid the formation of a continuous grate
or fuel bearer by the use of fire bars placed side by side transversely to the direction
of travel but not connected with each other each being provided at each end with
two axles (one above the other) formed on or connected thereto and a roller on

page_text: each axle travelling upon, (with one roller above and the other below,) an endless
rib constructed on and projecting from the inner side of each side frame and
supported by such rib without other support for the purpose and in the manner
substantially as hereinbefore and in the drawings described.
7. In such mechanical furnaces as aforesaid the formation of a continuous grate
or fuel bearer by the use of fire bars placed side by side transversely to the direction
of travel but not connected with each other each fire bar being made forked at each
end and fitted with a concave pulley or runner wheel having its axis in a vertical
plane all travelling upon endless ribs constructed (one or more) on the inner side of
each side frame of such size and shape as to fit into the hollow edge of the pulley
or runner wheel in such manner that the flanges of such pulleys or runner wheels
and therewith the fire bars may ride upon and be supported by such rib or ribs
without other support for the purpose and in the manner substantially as herein-
before and in the drawings described.
8. In such mechanical furnaces as aforesaid the formation of a continuous grate
or fuel bearer by the use of fire bars placed side by side transversely to the direction
of travel but not connected with each other and having grooved or forked ends in
combination with an endless rib or ribs constructed on each side frame such rib or
ribs fitting loosely into the grooved or forked ends of each fire bar in such manner
that the fire bars may ride upon and be supported by such rib or ribs without other
support for the purpose and substantially as hereinbefore and in the drawings
described.
9. In such mechanical furnaces wherein the fire bars are placed transversely in
the furnace and are mounted upon balls or rollers running in endless grooves or on
endless ribs formed as herein before mentioned and are not otherwise supported, the
method of operating or propelling such bars forward in the furnace by levers and
pawls and cam mechanism substantially as hereinbefore and in the drawings
described.
10. In such mechanical furnaces as aforesaid and in combination with hollow side
frames or spaces between the side frames and the boiler flue or furnace wall the use
of perforations through which air or air mixed with steam may be blown driven or
propelled for the purposes hereinbefore mentioned and in the drawings described.
11. The general construction and combination of parts to form a mechanical
furnace or grate substantially as hereinbefore and in the drawings described.
Dated this 19th do of Databox 1905
THOS. DALTON,
Solicitor,
65 Albion Street, Leeds, Agent for the Applicants.