Improvements in Mechanical Chain Grate Stokers for Steam Boiler or other Furnaces.
Year: 1898

page_text: Date of Application, 29th Dec., 1898-Accepted, 18th Mar., 1899
COMPLETE SPECIFICATION.
Improvements in Mechanical Chain Grate Stokers for Steam Boiler
or other Furnaces.
We, BABCOCK & WILCOX, LIMITED, of 147, Queen Victoria Street, in the
City of London, Steam Boiler Manufacturers, and GORGE WILLIAM Thode,
Engineer with said company, 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 mechanical stokers of the kind referred to in the
Specification of Letters Patent No. 21005 of 1890 wherein a revolving endless chain
oi chains composed of stoker links is carried on a wheel frame and forms the fine
grate of a furnace, and it has for its object to render such stokers more efficient
in action by improving the construction and arrangement of various parts as
hereinafter set forth
In the accompanying diawings which illustrate the invention Figure 1 18 a
sectional elevation of a water tube boiler of the Babcock & Wilcox type showing
the improved chain giate stoker applied thereto, Figure 2 is a front elevation,
and Figure 3 a plan of the same, Figures 2 and 3 shewing two sets of the geal
for driving the stoker Figure shows a modified method of carrying the chain
stoker
As shewn by these drawings the improved chain giate stoker is composed of the
usual wheel frame A carving upon sprocket wheels a revolving endless chain B
composed of stohei links b supported on rollers a, as shewn at Figure 1, or on
double rollera as at Figure 4, which are more closely spaced at the rear than at
the front of the furnace to better regulate the admission of air through the chain
grate, less an being required at the rear owing to the fuel resting on that part
of the grate being partially consumed and the fine being thinner
The chain giate B is slowly revolved by the rotation of the shaft C calving the
sprocket wheels & the said shaft having keyed on it a worm wheel D with which
geais a woim D on a spindle 12 which may be turned by a hand crank D³, but
which is also fitted with a ratchet wheel E keyed upon said spindle D and a
ratchet pawl e operated through a bevel sector f centied loosely on the spindle D³
and gearing with a sector f¹ on an aum connected by a link F and reciprocated by
a 1otating eccentric F1, the link F being adjustable as to length by means of a
nut f to regulate the extent of feeding motion The extent of the feeding motion
may be varied and it is regulated by means of a wheel loose upon the spindle D
provided with a number of teeth or notches and with a raised portion 3 over which
a roller on the actuating pawl e tavels, the pawl e thereafter acting on the
teeth of the keyed ratchet wheel E to turn the spindle Ds to the desired extent, a
pawle being provided to prevent the turning back of the ratchet wheel The
regulating wheel may be turned by hand to bring the raised portion ³ into such a
position that the roller e will act to a greater or less extent upon said portion
and to a proportionately greater or less extent on the teeth of the ratchet E, that
is to say, to engage from one to seven teeth at every stroke of the sector aim fª.

page_text: A pawl is provided which engages the teeth on the regulating wheel e³ to secure
this wheel in any desired position and prevent movement of the sanie
The fuel hopper G instead of forming part of on being secured on the movable
wheel frame of the stohei as is usual, is secured to the boiler or furnace front H
or to a projecting part thereof as shown at Figure 1, so that leakage of air between
the hopper and boiler front is obviated whilst the fuel in the hopper Gresting
on the cham grate closes off ingress of air above the fire The chain giate with
its diving gear is thus self contained and independent of the hoppei as indicated
a Figure 3
The arched furnace 100f I extending through the boiler front is fitted with a
lifting dom J for adjusting the depth of the fuel on the grate This door 19
aised or lowered by means of a lever aim and link from a lock shaft having on
it a worm wheel gealing with a worm on a spindle furnished with a hand
wheel This door also serves to keep the fuel from kindling outside
The side framing composed of the plates K sunk into the brickwork K' forms
part of the furnace instead of being formed on the wheel frame, and thus &
close fit is ensured between the framing and sides of the chain stoker to exclude air,
the setting of the side fiaming or brickwork K¹ being recessed to prevent clinker
adhering to the brickwork
A dumping plate L is fitted at rear of the stoker and rests at its lower edge on a
cross bai L o bickwork support, whilst its forward edge almost touches the chain
giate links so as to exclude ingress of air but allowing fine ash to pass over into
the pit M below Large and hard elinkei passes over the dumping plate L and
through the space into the pit The dumping plate is free to tilt or lift
upwards to allow of hard clinker passing under it should it tend to jam, the plate
immediately dropping to its noimal position after the passage of such clinker.
An ash seal is formed by the plate N dipping into the collecting ash, thereby
avoiding the use of doors which are liable to become twisted or not close tight
owing to ash getting between the doors and their frumes
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim 1.—
1 A chain giate stoker constructed and arranged to operate substantially as
described
2 The combination with a chain grate stoker of a boiler or other furnace
furnished with a fuel hopper and otherwise fitted as described to accomodate the
stoke and to exclude admission of air except through the fire grate.
3 In combination with a chain grate stoker a feed regulating device constructed
and arranged to operate substantially as described
In combination with a chain grate stoker and its furnace, a lifting door fitted
and operated as described to adjust the depth of fuel on the grate
5 In combination with a cham giate stoker and its furnace a dumping plate or
plates fitted at rear of the grate to prevent air leak and arranged to direct the ash
and clinker into the ash pit as described.
Dated this 28th day of December 1898
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents,
62, Saint Vincent Street, Glasgow, Agent for the Applicants