Improvements in and connected with Means for Preventing Smoke in Boiler and similar Furnaces.
Year: 1890

page_text: Date of Application, 1st May, 1890
Complete Specification Left, 20th Aug., 1890-Accepted, 20th Sept., 1890
PROVISIONAL SPECIFICATION.
Improvements in and connected with Means for Preventing Smoke
in Boiler and similar Furnaces.
I, THOMAS THORNLEY of Ash Villas, Tottington Road, Bury, in the County of
Lancaster, Manager, do hereby declare the nature of this invention to be as follows:-
This invention relates to the means employed for preventing smoke in boiler and
similar furnaces by which air is admitted at or beyond the bridge to produce and
promote secondary combustion, and it has for its object to regulate the admission of
the air in such a manner that the maximum amount is admitted when most required,
that is to say, immediately upon stoking, and is thereafter gradually cut off so that
by the time the fire has burnt up brightly and smoke no longer passes the bridge, the
supply of air is cut off automatically.
In proceeding according to these improvements, I control the opening or openings
(preferably below the bridge) by a damper or dampers weighted or arranged to
close the opening or openings unless forcibly opened or restrained from closing. The
damper or dampers is or are connected by rods chains or suitable means to a rack in
gear with a pinion, but so arranged that the rack may easily he lifted out of gear.
The pinion is mounted upon a slowly rotating shaft which may be driven by any
suitable means.
The damper or dampers is or are normally closed, but upon firing up, the stoker
lifts the rack out of gear and pulling it outwards, opens the damper or dampers. The
rack is then dropped into gear with the pinion and the damper or dampers can only
close as permitted by the rotation of the pinion. The air will thus be admitted in
full volume for secondary combustion as soon as fresh fuel has been added and this
volume will be gradually diminished by the closing of the dampers as the fire gradually
brightens and less smoke passes the bridge.
I prefer to lift the rack out of gear with the pinion as herein before described, but
if this is objected to, the pinion may be free upon the shaft and geared by a pawl to
a ratchet wheel fixed upon the shaft so that the pinion may rotate free of the shaft,
when the rack is drawn back, but will be rotated by the shaft in the opposite
direction.
Where there is no convenient driving power for the pinion, it may be rotated by
the weight of the dampers, in which case its motion may be retarded to the required
extent by a brake or by a weight and pulley or by other suitable means.
Dated this 30th day of April A.D. 1890.
WILLIAM E. HEYS,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in and connected with Means for Preventing Smoke
in Boiler and similar Furnaces.
I, THOMAS THORNLEY of Ash Villas, Tottington Road, Bury, in the County of
Lancaster, Manager, 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 means employed for preventing smoke in boiler and
similar furnaces by which air is admitted at or beyond the bridge to induce and
promote secondary combustion, and it has for its object to regulate the admission of
the air in such a manner that the maximum amount is admitted when most required,
that is to say immediately upon stoking, and is thereafter gradually cut off so that by

page_text: the time the fire has burnt up brightly and smoke no longer passes the bridgo, the
supply of air for secondary combustion is entirely and automatically discontinued.
In proceeding according to these improvements I control the opening or openings
(preferably below the bridge) by a damper or dampers weighted or arranged to close
the opening or openings unless forcibly opened or restrained from closing. The
damper or dampers is or are connected by rois chains or suitable means to a rack in
gear with a pinion, but so arranged that the rack may easily be liited out of gear.
The pinion is mounted upon a slowly rotating shaft which may be driven by any
suitable means.
The damper or dampers is or are normally closed, but upon firing up, the stoker
lifts the rack and pulling it outwards, opens the damper or dampers. The rack is
then dropped into gear with the pinion and the damper or dampers can close only as
permitted by the rotation of the pinion. The air will thus be admitted in full volume
for secondary combustion as soon as fresh fuel has been added and this volumo will
be gradually diminished by the closing of the dumpers as the tire gradually brightens
and less smoke passes the bridge.
I prefer to lift the rack out of gear with the pinion, as hereinbefore described, but
if this he objected to, the pinion may be free upon the shaft and geared with a pawl
to a ratchet wheel fixed upon the shatt so that the pinion may rotate free of the
shaft when the rack is drawn back but will be rotated by the shaft in the opposito
direction.
Where there is no convenient driving power for the pinion, it may be rotated by the
weight of the damper or dampers alone, in which case its motion may be retarded
to the required extent by a brake or by a weight and pulley or by other suitable
means.
I will more particularly describe my said invention with reference to the accoin-
panying drawings in which Figure 1 represents a longitudinal view of the flue of a
boiler having these improvements adopted thereto; Figure 2 a front end view of
Figure 1 and Figure 3 an elevation of one form of device which may be employed
for retarding the rotary motion of the pinion shaft.
A is the boiler flue; B is the bridge at the back of the furnace; C is an air-way
through the bridge; D is a door or damper closing the ashpit entrance to the air-
way C; D' is a chain or flexible metallic means for connecting the door 1) with the
rack E and F is a pinion capable of gearing with the rack and mounted upon the
shaft G.
The rack E is cut or cast upon a slide I which is provided with a handle I by
means of which the stoker immediately upon supplying fresh fuel to the furnace,
pulls the slide and rack outwards and thus opens the door D, admitting a fresh
supply of air from the ashpit through the airway in the bridge. Having pulled out
the slide, the stoker drops the rack thereon into gear with the teeth of the pinion F.
If the pinion or the shaft G upon which it is mounted were free to rotate, the weight
of the door D would at once close it, but if the pinion is compelled to rotate at a slow
speed, the closing of the door will obviously be effected slowly and the period during
which the closing is offected will be determined by the speed of revolution of the
shaft G. I prefer that this speed should be such that the door is completely closed
in about two or three minutes after opening but the actual time must he determined by
the local conditions in each caso.
The shaft G may be driven from any suitable source as for example from the
economiser engine or it may be rotated by the pull exerted by the weight of the door
through the chain and rack in which ease some means is adopted to retard the motion
or to regulate the speed of rotation of the pinion to the required extent. A brake
may be employed for this purpose, but since the action of a brake is uncertain
especially under such unfavourable conditions, I prefer to use some more positive means
such as an escape motion or a cataract cylinder. The application of an escape motion
is simple, it being necessary only to mount the escape wheel upon the shaft G, the
pallets being pivoted above the shaft, and the pendulum swinging beyond the end of
the shaft. In the case of the cataract cylinder or dash-pot, the arrangement shewn

page_text: in Figure 3 may be utilised. Here, H is an excentric mounted on the shaft G on
which the pinion F is also mounted; I is the connecting rod; K is the piston rod;
Lis the piston; and M is the cylinder. The cylinder is filled with glycerine, oil, or
other suitable fluid, and through the piston thero is formed a port or way which may
be contracted or opened by means of the set screw L'. By the rotation of the
shaft G the piston will be reciprocated in the cylinder and the liquid therein will be
caused to pass from one side to the other of the piston through the port. It will
therefore be obvious that the amount of retardation exerted against the rotation of the
shaft will be proportionate to the area of the port and that this may be regulated by
the screw L.
It will be understood that the brake, escape motion, cataract cylinder, or other
means for retarding or regulating the motion of the shaft G is applied only when the
shaft is rotated by the pull of the closing door D, and that it is not needed when the
shaft is driven by an engine or from any steadily moving mechanism.
In pulling out the rack in the act of opening the door D it will be necessary either
to lift the teeth of the rack out of gear with the teeth of the pinion or to so arrange
the pinion that while it is compelled to rotate with the shaft in one direction, (i.e. in
the direction tending to close the door) it is free to rotate freely on the shaft in the
other direction. I prefer as the simpler arrangement to arrange that the rack shall
be lifted and put into gear with the pinion in opening the door or damper, and I may
effect this by the means indicated in Figure 1 where N is a slot in the rack slide ;
O is a fixed pin passing through the slot N ; and P is a pin capable of being moved
vertically in a short slot Q in the fixing R and passing also through the slot N. Both
the pins O and P are held by the fixing R which acts as a support to the slido. With
this arrangement, when the handle I is lifted, the rack may be drawn forward with
its teeth clear of the teeth of the pinion, and when it has been withdrawn, the rack
may be dropped into gear and the door or damper will be gradually closed as herein-
before described.
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 1
claim is,
(1) In apparatus for preventing smoke in boiler and similar furnaces, the com-
bination and arrangement of an airway through the bridge, a door controlling the
airway, a rack connected to the door, a pinion on a rotary shaft capable of gearing
with the rack, and means for regulating or retarding the motion of the rotary shaft,
constructed and operated substantially as hereinbefore described and as illustrated by
the accompanying drawings.
(2) In apparatus for preventing smoke in boiler and similar furnaces, the com-
bination and arrangement of an airway through the bridge, a door controlling the
airway, a rack connected to the door, and a pinion mounted on a shaft rotated con-
tinuously at a slow speed, substantially as and for the purpose herein before described
and as illustrated by the accompanying drawings.
Dated this 19th day of August A.D. 1890.
WILLIAM E. HEYS,
Agent for the Applicant.