Improvements in Mechanical Stoking Apparatus for Furnaces.
Year: 1892

page_text: Date of Application, 24th June, 1892-Accepted, 3rd Sept., 1892
COMPLETE SPECIFICATION.
Improvements in Mechanical Stoking Apparatus for Furnaces.
I JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this invention (which has been com-
municated to me from abroad by Julien Belleville of St. Denis in the Republic of
France Engineer) 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 stoking apparatus in which the fire bars are
rocked or lifted at the front ends and at the back ends alternately some of the bars
being stationary and others being lifted at the front or back end only whilst others
are lifted at each end alternately as hereinafter explained. This apparatus enables
the clinkers to be readily detached and the spaces between the bars thoroughly
cleared of the cinder and scoria with which they are liable to be obstructed and
an unimpeded influx of air to the fuel is obtained at intervals regulated according
to the nature and quality of the fuel.
The fire bars employed in combination with this apparatus are preferably of the
form patented by my foreign correspondent and composed of bent plates connected
together in pairs. These bars are carried by transverse bearers and the mechanism
for moving the bars does not act upon them until they require to be moved and
being consequently not subjected to any continuous strain is enabled to be preserved
in working order for a long period of time.
And in order that the said invention may be fully understood I shall now proceed
more particularly to describe the same and for that purpose shall refer to the several
figures on the annexed sheets of drawings the same letters of reference indicating
corresponding parts in all the figures.
Figure 1 of the accompanying drawings illustrates in longitudinal and vertical
section a furnace provided with mechanical stoking apparatus according to this
invention and
Figure 2 represents the same in plan the greater portion of the fire-bars being
removed in order to expose the mechanism situated beneath the said bars.
Figure 3 represents the furnace in transverse section.
These drawings represent the apparatus in combination with the furnace of a
tubular steam generator of the Belleville type but the apparatus may be combined
with any other steam generator or furnace.
A are the fire bars made of bent iron plates coupled together in pairs being
represented as being of special form with trapezoidal undulations but the bars may
be of any other suitable shape. The bars marked 1 are immovable being retained
in position as hereinafter explained the other bars (marked 2, 3 and 4) are movable
and capable of being lifted either at the front or at the back.
Projections a placed at the front and at the back of the grate engage with the
forks at the ends of the bars 1 which are provided with pins 5 passing under the
projections a so as to prevent the bars 1 from rising when the other bars are rocked
or tilted but at the same time leave them entirely free to expand. The projections
maintain the bars 1 at suitable distances apart and divide the grate into a number
of equal sections each comprising four bars with sufficient play or space between
them to ensure the requisite freedom of motion.
In each of the spaces between the fixed bars 1 there are placed three movable
bars 2, 3, 4. All the bars whether fixed or movable rest upon bearers DD' at their
widest part where there is an opening between the two plates composing the bar
which are dressed or prepared at these points so as to enable each bar to stand
firmly upon the bearers. B is the dead plate, is a ledge at the back and sides of
the combustion chamber, c is the ashpit, D D' are the transverse bearers which

page_text: support all the bars at points about one quarter of their length from their ends the
distribution of the points of supports being as far as possible comprised between one
third and a quarter of the length of the bar. The bearers D D are supported at
the middle by trestles D₁!.
The mechanism for actuating the bars is supported by two girders E E' attached
to the bearers D'D at right angles to the latter These girders support a Hori-
-zontal shaft or rocker F carrying four longitudinal arms G supporting movable
plates which act upon the bars. The rocker F is provided with a lever K
connected by a link K' to a lever K" arranged outside the furnace working in
guides and made in two parts, one of which is removable.
The rocker F being constructed to present the requisite resistance to torsion works
upon knife edge bearings on the girders E and is prevented from being displaced by
stops 6.
A sheet metal screen or cover e" is placed over the rocker F in order to
protect it from the heat of the furnace.
The plates H H rest upon blocks' attached to the arms G. The blocks are
provided with notches for the reception of the plates H H and the latter are
hevelled and adjusted in the bottom of the recesses in the blocks has represented
in Figure 1 so as to limit the amplitude of their oscillation. Small counterweights
not shewn in the drawing are placed on the extremities of levers attached to these
plates H H in order to cause them to return automatically to their original position
(represented in Figure 1) directly they are out of contact with the bars after each
rocking motion.
The plates H H¹ are provided on their upper edges with rectangular recesses as
represented in Figure 3 so arranged that the projecting parts between the said
recesses in the plate H act upon the bars 2 and 3 only whilst the corresponding
projecting parts in the plate H act upon the bars 3 and 4 only.
When the apparatus is out of action the parts occupy the position represented in
full lines in Figure 1 the dotted lines in this figure indicating the position occupied
by the bars when raised. The fire bars are normally supported upon the bearers D
so as to leave a certain amount of play or space between these bars and the
plates and enable these plates to be returned to the position indicated in
Figure by the action of the levers and counterweights hereinbefore referred to.
By lowering the external lever K" the link K¹ pulls the lever K towards the
left hand in Figure 1 and by rocking the rocker F causes the arms G to assume an
inclined position. The front plates H are raised and the back plates H descend.
The projecting parts of the front plates H come in contact with the bars 2 and 3
Figure 3 but do not act upon the bars 4 which are situated over the recesses in the
said plates. The front ends of these bars 2 and 3 ouly are lifted these bars being
caused to oscillate upon the hinder bearer D' acting as a fulcrum. By this move-
ment the bars marked 2 and 3 are raised as indicated by dotted lines in. Figure 1
and on the left hand in Figure 3 but the bars 1 and 4 remain stationary.
By moving the lever K in the opposite direction the movement of the link K¹,
lever K and arms G is reversed the front plates H descend and the rear plates Hi
ascend. The rear ends of the bars 3 and 4 are now clevated being caused to
oscillate upon the front bearer D as represented on the right hand in Figure 3 but
the bars and 2 which are situated over the recesses in the plates H' remain
stationary.
The bars being grouped in sets of four, the effect of this arrangement is that the
bars marked I are permanently stationary the bars 2 and 3 are elevated simul-
taneously at the front end and the bars 3 and 4 are similarly elevated at the rear
end the bar 3 being clevated at the front and at the rear alternately.
When the bars are elevated at the front end the rear end is lowered to the extent
of say one third of the distance to which the front end is raised and in like manner
when the bars are lifted at the rear end the front end is lowered to one third of the
distance to which the front end has been raised..
It results from this combination that each bar is displaced relatively to the
adjacent bar with a shearing movement which is most favourable not only for

page_text: detaching and breaking up the clinkers but also for effectually clearing the spaces
between the bars. The bars are always lifted in pairs of two contiguous bars
thereby facilitating their descent by reducing the frictional resistance.
When the
front plates H for example oscillate with the arms G which carry them the laterally
oscillating movement of the upper edges of the plates is stopped directly these
edges come in contact with the bars to be raised after which the plates H rock in
the recesses in the blocks h which are made of sufficient width to provide for this
movement of the plates.
The plates H at the back work in the same way and it results from this com-
bination of arrangements that the resistance to the oscillating movement of the bars
is reduced to a minimum. The rocking movement of the plates H obviates the
sliding of the bars upon their supports or bearers which would otherwise inevitably
take place and create a corresponding resistance if these plates were not arranged
to act as connecting rods or links.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what 1
claim is :-
The combination and arrangement of mechanism for agitating or moving furnace
fire bars constructed and operating substantially as hereinbefore described and
illustrated in the accompanying drawings.
Dated the 9th da of Lun 1000
J. H. JOHNSON & Co.,
Agents.