Improvements in the Means of Consuming Smoke in Mechanical or Hand Stokers with Moving Fire Bars.
Year: 1891

page_text: Date of Application, 31st Oct., 1891
Complete Specification Left, 2nd Aug., 1892-Accepted, 30th Nov., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Means of Consuming Smoke in Mechanical or
Hand Stokers with Moving Fire Bars.
I, ISAAC SHIMWELL MCDOUGALL, of High Bank, Didsbury, in the County of
Lancaster, Manufacturing Chemist, do hereby declare the nature of this invention
to be as follows:-
:-
My invention relates to hand or mechanical stokers for land and marine boilers,
and to furnaces generally, in which moving fire bars are used, and it consists of
improved arrangements for directing air into the furnace at or near the fire bridge
in such manner as to effectually consume smoke and at the same time present an
arrangement which cannot be readily deranged by ash or clinker.
In one mode of carrying my invention into effect as applied to hand stoking, I
construct a brick bridge wall upon a suitable plate and above this plate within
the brickwork I bolt or secure a casting with a recess or hollow opening to the
furnace side of the bridge.
Perforations, slits or openings are made which lead into this hollow, and air is
passed under the fire bars from the ash pit by a movable deflecting plate closing the
space between the lower part of the bridge and the bottom of the flue. The air
enters the said perforations, slots or openings and passes into the end of the furnace
by the recessed plate forming part of the bridge wall. The air is thus directed
to the inner end of the fire and consumes the gases still remaining unburned
and so prevents smoke.
The air supply is controlled by a swinging door connected to the boiler front
by a chain or rod which serves for its adjustment, and the door is constructed so
as not to close entirely. It always kept sufficiently open to allow ash or dust
falling over the ends of the moving fire bars to pass freely to the bottom of
the flue.
In another mode of carrying my invention into effect, a space is left between
the upper edges of the fire bar ends and the underside of the carrying plate of
the fire brick bridge; this space is not a continuous open space but is divided
into small air spaces by suitable ribs or castings, and air finds its way from the
regulating door through these spaces also. The moving fire bars may be operated
in any convenient known manner, and the motion may be reciprocating or pro-
gressive as desired.
The plates having the air discharging recess are made removable in order to
conveniently renew them when burned out, and the aperture facing the furnace
is protected by projections which may or may not be covered by fire brick to form
a series of slots through which air passes to the inner end of the furnace.
In another mode of carrying my invention into effect as applied to mechanical
stoking, instead of passing the air as above described, I construct a hollow casting
to carry the inner ends of the reciprocating fire bars and I control the passage
formed by this hollow casting, by a suitable swinging door controlled by rod or
chain from the boiler front. "I pass air through this hollow casting and cause it to
discharge at its external end, so consuming the gases from the furnace and preventing
smoke. Under this swinging door is provided a larger swing door for withdrawing
of clinkers.
This arrangement has the advantage that ash and clinker is simply pushed over
the hollow casting by the advancing fuel and drops to the bottom of the flue whence
it may readily be withdrawn by the door already described.
The casting is preferably shaped so that the air apertures at the discharge end
are protected and the air is turned up through the flames leaving the furnace to
travel along the flue.

page_text: The admission of air to the hollow casting may also be controlled by a suitable
chain or rod actuated swinging door.
Dated this 29th day of October 1891.
CLERK & MARKS,
13, Temple Street, Birmingham, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Means of Consuming Smoke in Mechanical or
Hand Stokers with Moving Fire Bars.
1, ISAAC SHIMWELL MCDOUGALL, of High Bank, Didsbury, in the County of
Lancaster, Manufacturing Chemist, 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 :-
My invention relates to hand or mechanical stokers for land or marine boilers,
and to furnaces generally, in which moving fire bars are used, and it consists of
improved arrangements for directing air into the furnace at or near the fire bridge
in such a manner as to effectually consume smoke, and at the same time present an
arrangement which cannot be readily deranged by ash or clinker.
In carrying my invention into effect, a space is left between the upper edges of
the fire bar ends and the under side of the carrying plate of the fire brick bridge;
this space is not a continuous open space but is divided into small air spaces by
suitable ribs or castings, and air finds its way from the regulating door through
these spaces also. The moving fire bars may be operated in any convenient known
manner, and the motion may be reciprocating or progressive as desired.
The plates having the air discharging recess are made removable in order to
conveniently renew them when burned out, and the aperture facing the furnace is
protected by projections which may or not be covered by fire brick to form a series
of slots through which air passes to the inner end of the furnace.
In another mode of carrying my invention into effect as applied to mechanical
stoking, instead of passing the air as above described, I construct a hollow casting
to carry the inner ends of the reciprocating fire bars and I control the passage
formed by this hollow casting, by a suitable swinging door controlled by rod or
chain from the boiler front. I pass air through this hollow casting and cause it to
discharge at its external end, so consuming the gases from the furnace and
preventing smoke. Under this swinging door is provided a larger swing door for
withdrawing of clinkers.
This arrangement has the advantage that ash and clinker is simply pushed over
the hollow casting by the advancing fuel and drops to the bottom of the flue
whence it may readily be withdrawn by the door already described.
The casting is preferably shaped so that the air apertures at the discharge end
are protected and the air is turned up through the flames leaving the furnace to
travel along the flue. The admission of air to the hollow casting may also be
controlled by a suitable chain or rod actuated swinging door.
The invention is clearly shown by referring to the accompanying drawing.
Figures 1, 2 and 3 are respectively a front elevation, longitudinal section, and
cross section through one flue of a Lancashire boiler fitted with moving fire bars,
fired by hand combined with the improved arrangement of bridge wall..
Figure 4 is a detail sectional view of the arrangement of improved bridge wall as
applied to the moving bars of mechanical stokers.
Figures 5, 6, 7 and 8 are details of the moving bar arrangement shown in Figures 1
and 2.
The method I use to obtain motion of the fire bars in arrangement shown on
Figures 1 and 2 is briefly as follows. On the front plate of the boiler, Figure 1,
three pedestals A, A, A, are bolted. A strong square wrought iron or steel

page_text: shaft B, suitably journalled, revolves in these pedestals and it is placed just
underneath the fire bars. On the square part of this shaft B, a number of eccentric
cams C, C, C, are placed and there is one of these cams to each fire bar. The
fire bar end D is suitably forked to embrace the cam and each cam is (preferably)
arranged alternately and at right angles to the next one, so that the differential
motion between the adjacent fire bars may loosen the clinker. This arrangement
of cam and fire bar end is clearly shown in detail in Figures 7 and 8. On each end
of the shaft B are keyed ratchet wheels E, E, and from bosses on those wheels
swing arms F, F, are carried, which in turn support pawls G, G, gearing into the
ratchet wheels. The ratchet wheel, pawl and swing arm are clearly shown in
detail, Figures 5 and 6. The ratchet wheel and pawl are actuated from the
overhead countershaft H by the eccentrics I, I, and. connecting rods K, K, and
This arrangement
power is given to the countershaft from any convenient source.
gives a regular steady movement of the fire bars, thus keeping the air spaces clear
of any clinker and ensuring combustion.
The arrangement of bridge wall as applied to the hereinbefore described moving
bar furnaces is clearly shown in Figures 2 and 3. The fire bar ends L, L, L, rest
on the cross bearer M. A strong cast iron dead plate N, is placed a short distance,
above the fire bars and it is prepared for and filled in on its upper surface with
the fire bricks or tiles 0, 0, 0. This dead plate N rests on a short brick bridge
wall P of the usual type. On the under part of the bar bearer M is fixed a small
swing door Q controlled by a chain or other suitable means. A cast iron plate R
projecting from the underside of the dead plate N meets this door Q as shown in
Figure 2. The brick wall P prevents the passage of air in that direction and the
only passage left is up and round the end of the fire bars and over the bridge wall
as shown by arrows in Figure 2, and this passage is fully controlled by the opening
and shutting of the door Q. Immediately over the fire bar ends and fixed to the
underside of the dead plate N is a small cast iron angle plate S. This plate S is
perforated all along its side with small slots T, T, T, clearly shown in Figure 3.
The function of these slots is to divide the air passing up and over the fire bar
ends into thin streams so that they may more readily mix with and promote the
combustion of the gases immediately over the bridge wall. This arrangement
thus provides a means of admitting air at the bridge wall to assist combustion when
the fires are heavily pressed and also by causing a stream of cold air to pass over
the fire bar ends prevents them being quickly burnt out at this part, which is a
common occurrence in present practice.
The arrangement of bridge wall I propose applying to mechanical stokers is
shown in the longitudinal part section through the flue of a Lancashire boiler at
Figure 4. The dead plate U consists of a strong hollow box casting left open at
both the front and back end. This dead plate U tapers away to the back end and
the opening there V is reduced to a shallow slot the full width of the box. At the
front end the opening W is nearly the full depth of the box. Pivotted on the
front end and closing against the opening W is a small swing door X controlled by
a chain or other suitable means. The space underneath, between the box dead
plate and the flue is made up by the ash door Y and its framing so that the only.
passage for the air at this end is through the box dead plate in the direction shown
by the arrows; and this passage is controlled by the swing door X. This
arrangement thus provides a means for admitting a flat thin stream of air behind
the bridge wall when the fires are heavily pressed thus ensuring complete
combustion and prevention of smoke.
This description of dead plate U may in like manner be applied to moving fire
bars for the working of hand fired boilers or furnaces.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be carried into effect I declare that
what I claim is :-
:―
1. The arrangement of bridge wall and air box with serrated slot or long

page_text: aperture as applied to moving bars as hereinhefore described and illustrated on
Figures 1, 2 and 3.
2. The combination of the bridge wall as applied to moving fire bars with the
special form of moving bar arrangement as hereinbefore described and illustrated
in the drawing on Figures 1, 2, 3, 5, 6, 7 and 8.
3. The arrangement of bridge wall and air box with discharge slot as applied to
moving bars of mechanical stokers or moving fire bars as hereinbefore described
-and illustrated in drawing on Figure 4.
Dated this 29th day of July 1892.
CLERK & MARKS,
13, Temple Street, Birmingham, Agents for the Applicant,