Improvements in Furnace Grates.
Year: 1894

page_text: Date of Application, 12th July, 1894-Accepted, 18th Aug., 1894
Improvements in Furnace Grates.
1, MICHAEL FITZ-MICHAEL MULREADY, of 7 Wentworth Place, Newcastle-
on-Tyne, Engineer, 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 improvements in furnace grates whereby a more perfect
combustion of fuel is obtained than in furnace grates of ordinary construction.
It consists in an arrangement of furnace bars whereby each bar has a vertical
angular reciprocating motion imparted to it in such manner that each bar
reciprocates in the contrary direction to the adjacent bars, and that the extent of
motion of the bars at the inner end is greater than that at the front end, so that
y this means not only is an effectual breaking up of the fuel on the grate with a
gradually increasing motion towards the inner end effected, but also a gradually
increasing admission of air through the grate is effected towards such inner end,
thereby both preventing clinker and insuring a more intense combustion towards
the inner end and an excess in the supply of heated oxygen for burning the
unconsumed gases that may pass inwards from the front end of the furnace.
This gradually increasing activity of the combustion will take place in a
uniformly distributed manner over the whole grate surface, so that when a forced
draught is employed any such detrimental blow-pipe action as now frequently
occurs owing to the forced air passing with great rapidity through parts of the
fuel where it meets with the least resistance, will be prevented, thus doing
away with the only disadvantage that is at present attendant on the use of forced
draught.
The furnace grate may be constructed in various ways for carrying out my said
invention; thus according to one construction I employ a single set of fire bars,
arranged to rock on a fulcrum situated just below the inner end of the dead plate,
the bars having outward extensions below the dead plate, the ends of which project
outside the furnace and are there acted upon by cams on a revolving shaft
or by equivalent devices so as to impart to the bars the above described vertical
reciprocating motion.
Thus it will be seen that the bars will have a gradually increasing angular
motion from the fulcrum at the dead plate, to the inner end, producing the above
described result.
According to another construction, I provide two sets of bars in the direction
of the length of the furnace grate; the bars of the front set, which have their
fulcrum at the dead plate as above described, have their inner ends formed with
teeth which engage with corresponding notches in the front ends of the inner set of
bars, which have their fulcrum at a point considerably nearer to their outer end
than to their inner end, so that the outer set of bars will communicate the
reciprocating motion of their inner ends to the outer ends of the inner set, and
such motion will be imparted in a gradually increasing manner to the inner ends
of these bars.
In like manner three or more sets of bars may be arranged in the length of the
furnace, and the motion be transmitted from the one set to the other in such manner
that each set of bars has a greater amount of motion than the bars of the next
outward set.
Fig. 1 of the accompanying drawings shews a longitudinal section of a furnace
grate constructed according to my invention with a single set of bars; Fig. 2 shews
a part plan, and Fig. 3 shews a front view. The bars A which
be of any
may
suitable cross section, are carried at a point immediately below the inner end of

page_text: the dead plate B, by a cylindrical support C round which they fit with a semi-
circular hollow; beyond this point the extensions A¹ project to the outside of the
furnace where they are acted upon by a cam shaft D, the cams D' of which are
so formed as by their rotation to alternately depress the extensions A' of the
contiguous bars, thereby raising up the inner ends of the bars A to a proportionately
greater extent.
On the cams receding from the extension A' the inner ends descend again, the
extensions being kept up against the cams by the preponderance of the weight of
the parts A.
The support C is by preference constructed as follows:
A transverse bearer C' of a T section is supported at its ends upon brackets E
on the sides of the ashpit, and upon this bearer is slid a tubular sleeve C, having
an internal flat surface C' resting upon the flat top of the bearer, while externally
it has a number of collars C corresponding to the number of the furnace
each of which is consequently held in position by fitting with its rounded."
the space between the collars.
.
1
g
19
The sleeve C might also be made of semi-circular section instead of tubular.
In order to prevent larger particles of fuel from penetrating, into the spa
between the dead plate B aud the extensions A' of the bars, I construct the inne.
edge of the dead-plate with a chisel-edged rib B' which is situated close to
tops of the bars, immediately above the centre of the support C, whereby a
small particles of fuel that may possibly penetrate between the two will become
crushed by the action of the bars in moving slightly to and fro at that point, and
consequently such crushed particles will not interfere with such motion.
I prefer to arrange the furnace grate at some distance below the centre line of
the cylindrical fire box as shewn, in order to afford more space above the grate for
combustion of the gases.
As a certain amount of space must be left between the
end bars of the grate and the curved sides of the fire box, in order to allow of the
above described motion of the bars, I enclose such spaces with narrow dead plates F
having inclined top surfaces in order to prevent the fuel from lodging thereon.
The angular reciprocating motion of the bars is preferably made to extend from
about the horizontal position shewn by the front bar at Fig. 1, downward to the
point below such position shewn by the bar end the front one.
By this means the fuel, in being broken up, will have a certain tendency to travel
inward towards the fire bridge, and a certain space may be left between the ends
of the bars and the plate of the fire bridge, for the ashes that may travel
forward to fall through.
The cam shaft D is carried in brackets G fixed to the door-frame of the fire-
box, and it receives its rotary motion from any convenient source of power,
such as a mill shaft H carrying a worm I gearing with a worm wheel J on
the cam shaft.
Fig. 4 shews a longitudinal section of the arrangement in which there are
two sets of fire bars, namely an outer set A receiving reciprocating motion from
a cam shaft as before and an inner set K, receiving its motion from the outer
set. For this purpose the bars A are formed with teeth a and recesses a¹ with
which engage corresponding recesses and teeth of the bars K. As the
bars A have to impart the up and down motion to the bars K, it is preferred
to impart a positive upward motion as well as a positive downward motion to the
extensions A1; this is effected by providing two sets of cams D' L' on separate
shafts DL, the one set acting on the upper side of the extensions A' and the other
on the underside, the canis being suitably formed as shewn to "fit and fill."
By suitably weighting the bars however, a single cam motion might be used as in
the first arrangement.
The lower cam shaft is in this case driven by worm and worm wheel gear from
the driving shaft and imparts its motion to the upper cam shaft through equal spur
pinions.
In this case, as the bars A in having their extensions A' raised for depressing the

page_text: re
front ends of the bars K will meet with some resistance from the latter, it is
necessary to provide means for preventing the former from being lifted off their
support C by such action; this is effected by forming the bars A with an oblique
slot as shewn, so that when A¹ is raised, the inclined edge A' of the slot, in coming
in contact with the underside of the support C, will prevent the bar from being
raised from the latter.
The bars K have their support M at a short distance from the front end, so that,
as before described, the vertical reciprocating motion of the inner ends of the bars
will be correspondingly greater than the vertical motion of the inner ends of the
bars A.
With this arrangement it is preferred to place the support M of the inner set
of bars at a lower level than the support C of the front bars so that when the
latter are moved into the depressed position the inner bars K will be about
horizontal, while when the bars A are raised to the horizontal position, the bars M
nge their inner ends depressed, as shewn on the drawing.
Having now particularly described and ascertained the nature of this inven-
Y" on and in what manner the same is to be performed, I declare that what I
Paim is :-
ני
Constructing furnace grates with fire bars supported on fulcra near their front
s and receiving a vertical reciprocating motion upon such fulcra, in such manner
that the adjacent bars reciprocate in opposite directions and that the extent of
motion gradually increases from the front end to the inner end, substantially as
and for the purposes described.
2. In furnace grates constructed and operating as set forth in the first claim,
providing the fire bars with extensions projecting beyond the furnace front and
acted upon by cams upon a revolving cam shaft, substantially as described.
3. In furnace grates such as are referred to in the first claim, the combination
with a front set of vertically reciprocating bars A, mounted on a support C near
the front end, of a second inner set of bars K mounted on a support near their
front end and geared with the front set of bars A in such manner that the vertical
reciprocating motion imparted to the b A is imparted to a gradually increasing
extent to the inner end of the bars bstantially as described.
4. In furnace grates such as are referred to in the first claim, the combination
with a front set of vertically reciprocating bars A mounted on a support C near the
front end, of two or more sets of vertically reciprocating inner bars, in line with
the first set, each such inner set being geared with the next outer set so that the
angular reciprocating motion imparted to the front set of bars is transmitted in a
gradually increasing manner to the innermost set, substantially as described.
5. In combination with a vertically reciprocating set of furnace bars, such as are
referred to in the first claim, the use of a dead plate having a chisel edged rib at
its inner end situated immediately above the centre of the support of the front bars
and close to the upper surface of the latter, substantially as and for the purposes
described.
6. In combination with vertically reciprocating furnace bars such as are referred
to in the first claim a support for the bars to rock upon, consisting of a Tiron
transverse bearer C¹ on which is placed a tubular or semi cylindrical sleeve C
having collars C' between which the separate bars are held in position, substantially
as described.
7. In furnace grates with two or more reciprocating sets of bars such as are
referred to in the 4th and 5th claims constructing the front bars A with slots having
oblique sides fitting over the support C, substantially as and for the purposes
described.
1.
out
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T 1 1004
ABEL & IMRAY,
Agents for the Applicant.