Improvements in Fire Grates for Furnaces for Steam Boilers.
Year: 1893

page_text: Date of Application, 3rd Mar., 1893
Complete Specification Left, 4th Dec., 1893-Accepted, 6th Jan., 1894
PROVISIONAL SPECIFICATION.
Improvements in Fire Grates for Furnaces for Steam Boilers.
We HENRY TAYLOR GRUNDY of Radcliffe near Manchester in the County of
Lancaster, Mining Engineer, and WILLIAM CRITCHLEY of Radcliffe near
Manchester in the County of Lancaster, Engineer, do hereby declare the nature of
this invention to be as follows:
Our invention has for its object the more complete combustion of fuel in furnaces
of steam boilers, and it is also applicable to other furnaces. We employ hollow
bars for the grate formed with longitudinal holes and constructed in one or more
pieces in any known manner, provided only that it is an important part of our
invention that the inlets and outlets of the said holes be champfered or bell-
mouthed. The front ends of the said bars rest in the ordinary way upon a hollow
dead plate of special construction. The said dead plate is formed as a shallow box
open at the back and front, and having a lid resting upon the sides and also upon
the front ends of the bars, a short length of which is cut down to the thickness of
the said lid so that the upper surface of the lid is level with the upper or fire
surface of the bars. The said lid is not necessarily loose from the dead plate box
but may be fastened to it or cast with it. Opposite to and central with the end of
each bar, a hole is formed in the bottom or floor of the dead plate box which holes
are controlled by a sliding plate working in grooves or otherwise suitably held
underneath and in contact with the said floor, and which can be operated by hand
from the front of the boilers. We place a block or casting having "through
air chambers corresponding with the bars in the dead plate box and within a short
distance of the fire bar ends. The passages through the said block are enlarged
towards the front so as to leave only narrow edges between the openings in the
block. A plate closes up the front end of the box with the exception of a hole
or holes for the introduction of air by natural or forced draught, and between the
Baid front plate and the block there is a space to allow for the distribution of air
to the various openings in the block.
"
The back bearer and bridge carrier is also of special form and is an important
part of our invention. The back ends of the bars which are of similar form to the
front ends, rest upon a cross bearer which is extended downwards thus closing up
the back of the ashpit with the exception of a hole which is left for the purpose of
cleaning-out the chamber beyond. A hinged door which can be opened by a chain
or rod or other suitable device closes up this aperture. At the back of the said
cross bearer a ledge is formed upon it which may be continuous or not and which
is preferably turned up at the edge to embrace a small flange formed on the under-
side of the bridge frame to be hereafter described. Resting upon the said ledge
we place an open horizontal frame, whose back edge rests upon a bearer of similar
construction but without the aperture for cleaning-out. The back and front
members of the said frame are connected by three or more ribs, but the openings
in the frame are made as large as possible to allow such clinker or ash as may be
carried over the bridge to drop freely upon a plate forming the floor of the space
between the two bearers before described, and which is level with the lower edge
of the cleaning-out hole in the bearer as described. The said plate or floor may
be curved approximately to the form of the flue and it is carried upon ribs or
ledges formed upon the bearers which are preferably turned up to embrace small
flanges or snugs formed on the under side of the floor plate. Upon the side and
intermediate ribs of the frame brackets are formed to carry an angle plate upon

page_text: which the brick bridge is built, and which while it rests upon the said brackets
projects also partially over the back end of the bars which are cut down similarly
to the front ends for the purpose. The brackets are formed with abutments to
prevent the bridge angle piece from being pushed out of place.
The front end of the ashpit is not closed but left free for the ingress of air
between the bars (which are provided with the usual distance pieces) in the
ordinary way.
It will thus be seen that we provide by the construction of the hollow front
dead plate for air to have access to the hollow bars either through the front plate
of the box by natural or assisted draught, or through the floor of the box at will,
or by both means simultaneously.
In some cases we heat the air supplied through the front plate of the box by
causing it to pass through a pipe carried along the upper part of the side flues or
by other means but this forms no part of our present invention.
It will also be seen that we provide for the efficient cleaning-out of the space
beyond the bridge as it is impossible for any clinker, ash, or unburnt fuel to fall
beyond the second bearer, and further that we construct the whole of the back
bearer frame and bridge carrier without the use of bolts.
The heated air emerging from the back of the hollow bars passes under the
brick bridge and mixing with the gases beyond promotes secondary combustion.
The arrangement of back bridge bearer projecting over the ends of the bars
renders it impossible for the discharge of air through the bars to become obstructed
by clinker, ash, or refuse which may be carried over the bridge, as such refuse
must fall direct upon the floor of the chamber between the two bars and can be
readily cleaned-out by the door described.
Dated this 24th day of February 1893.
EDGAR CONISTON MILLS,
Agent to the Applicants.
COMPLETE SPECIFICATION.
Improvements in Fire Grates for Furnaces for Steam Boilers.
We, HENRY TAYLOR GRUNDY of Radcliffe near Manchester in the County of
Lancaster, Mining Engineer and WILLIAM CRITCHLEY of Radcliffe near
Manchester in the County of Lancaster, 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 :-
Our invention has for its object the more complete combustion of fuel in
furnaces of steam boilers, and it is also applicable to other furnaces, and in order
that our invention may be more readily understood we refer to the accompanying
drawings.
Fig. 1 is a longitudinal sectional elevation taken through the centre-line of a
boiler flue having our improved firegrate applied to it.
Fig. 2, is a sectional plan taken just above the bars and having in its upper half
view the top plate of the dead plate removed, and a portion of the fittings
thereunder shown in section.
at xx
Fig. 3 is a cross section taken, in respect to its left half view, through the bars
Fig. 1. and in respect to its right half view through the line y y Fig. 1.
Fig. 4 is a detached sectional view of the front plate taken through the line z z
Fig. 3.
AA are the hollow bars formed with longitudinal holes a. a.
One or more
lengths of bars can be employed as desired. The inlets and outlets of the bars
are bell mouthed as shown at a' a'. The front ends of the bars rest upon the
hollow dead plate B which is formed as a shallow box open at the back and front

page_text: and having a lid b resting upon the sides and on the bar ends which are cut down
as shewn to allow the upper surfaces of the lid and bars to be level.
The lid 6 may if desired be cast or otherwise formed with the box B. Opposite
to and central with each bar a hole is formed in the floor of box B which holes
are controlled by a sliding plate C working in grooves or otherwise suitably
held in contact with the underside of the said floor and which can be operated by
hand from the front of the boiler by the handle c. We place a block D within
the box B having "through" air passages dd one corresponding with each bar.
The said passages are enlarged towards the front as shown both in Fig. 1
and Fig. 2. A plate or block E closes the front end of the box B'having one or
more inlets ee for air ingress by either natural or forced draught. Between E
and D a space is left or a groove e' cut in E for the distribution of the air to the
passages in the block D.
The back ends of the bars which are of the same form as the front ends, and
the orifices similarly bell-mouthed, rest upon a cross bearer F which extends
downwards as shown, thus closing up the back of the ashpit M with the exception
of the hole which is left for the purpose of cleaning out the chamber beyond.
A hinged door G which can be opened by a rod g or other similar device closes up
this aperture.
A second cross bearer or vertical plate H is placed beyond F and resting upon
the ledges or brackets and f' formed upon these bearers respectively a horizontal
open frame I is placed, formed with large openings as shown clearly in Fig. 2.
A floor K is provided on a level with the lower edge of the door opening and is
also carried by brackets f' and h¹ formed with the bearers F and H. These
brackets as well as the brackets f' and h are preferably formed with turned up
flanges as shown embracing ribs formed on the underside of the floor K and
frame 1 by which means bolts are avoided and the bearers are braced together.
The floor K may be curved as shown in Fig. 3 to suit the form of the flue. Upon
the longitudinal members of the frame I brackets k are formed to carry an angle
plate L upon which the brick bridge V is built and which also projects over the
back ends of the bars which at this end are cut down similarly to the front ends
for the purpose. The brackets k are formed with abutments k¹ to keep the angle
plate L in place. A deflector plate N is mounted upon the back part of the
hollow bridge to deflect the current of heated air coming through the bars
upwards so as to thoroughly mix them with the unconsumed gases passing over the
bridge, and in order to effect this more thoroughly the said deflector plate is
preferably fluted or corrugated.
The front end of the ashpit is not closed but left free for the ingress of air
between the bars (which are provided with the usual distance pieces) in the
ordinary way.
It will thus be seen that we provide by the construction of the hollow front
dead plate for air to have access to the hollow bars either through the front plate
of the box by natural or assisted draught, or through the floor of the box at will,
or by both means simultaneously. The object of allowing the current of cold air
from below the bars to pass by the holes 6' is to prevent clinker from adhering to
the bars and to provide a current of hot air to pass below the brick bridge.
In some cases we heat the air supplied through the front plate of the box by
causing it to pass through a pipe carried along the upper part of the side flues or
by other means but this forms no part of our present invention.
It will also be seen that we provide for the efficient cleaning-out of the space
beyond the bridge as it is impossible for any clinker, ash, or unburnt fuel to fall
beyond the second bearer.
The heated air emerging from the back of the hollow bars passes under the
brick bridge and mixing with the gases beyond promotes secondary combustion.
The arrangement of back bridge bearer projecting over the ends of the bars
renders it impossible for the discharge of air through the bars to become obstructed
by clinker, ash, or refuse which may be carried over the bridge, as such refuse

page_text: must fall direct upon the floor of the chamber between the two bars and can be
readily cleaned out by the door described. To the inside of the door of the
furnace we attach an air conducting box P for the purposes of guiding the
current of air admitted through the controllable orifice o in the door and directing
it downwards upon the first portion of the fuel on the bars as shown by the
arrows. It serves the further purpose of protecting the door O somewhat from
the heat of the furnace.
We preferably attach it without bolts and construct the slides or grooves o' on
the door to receive it.
We also attach a box plate R Figs. 1 and 4 to the inside of the furnace front
plate S for the purposes of guiding the current of air admitted through the
controllable orificer in the front plate and directing it also downwards upon the
nearest portion of the fuel by the inclined apertures Fig. 4.
The object of these air directing boxes is to promote primary combustion in the
front portion of the fire, which combined with the secondary air admitted as herein-
before described through the bars and bridge results in entire consumption of
smoke and considerable economy of fuel.
I
The object of forming the orifices of the bars bell-mouthed is to avoid eddying
of the draught and so to decrease resistance to the power of the chimney.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. The hollow firebars having enlarged or bell mouthed orifices at each end
substantially as and for the purposes herein before described and illustrated in the
accompanying drawings.
2. The hollow firebars having bell-mouthed orifices and cut down or stepped at
each end to allow the dead-plate at one end and the bridge-plate at the other to
project over the ends of the bars, substantially as and for the purposes hereinbefore
described and illustrated in the accompanying drawings.
3. The hollow dead plate having the cold air inlet holes controlled by a sliding
or other door or valve substantially as and for the purposes hereinbefore described
and illustrated in the accompanying drawings.
4. The hollow dead-plate having the conducting block D with the bell-mouthed
passages substantially as and for the purposes hereinbefore described and illustrated
in the accompanying drawings.
5. The hollow back bridge formed with two cross bearer plates and horizontal
top frame carrying a bridge plate projecting over the back end of the bars and
having the brick bridge built upon it, substantially as and for the purposes hereiu-
before described and illustrated in the accompanying drawings.
6. The hollow back bridge with open top frame and having the outlets of the
hollow fire-bars placed above the said frame and below the plate on which the
brick bridge is built substantially as and for the purposes hereinbefore described
and illustrated in the accompanying drawings.
7. The hollow back bridge with open top frame and having the brick bridge so
placed that any cinder or other material falling over it must fall through the said
frame into the hollow of the back bridge substantially as and for the purposes
herein before described and illustrated in the accompanying drawings.
8. The hollow back bridge with open top frame and provided with a false bottom
or floor to receive cinder or other refuse falling over the bridge and capable of
being cleaned by means of an opening in the front plate of the bridge closed at
will by a door, substantially as and for the purposes herein before described and
illustrated in the accompanying drawings.
9. The corrugated and angled deflector plate at the back of the hollow bridge
substantially as and for the purposes herein before described and illustrated in the
accompanying drawings.
10. The front air inlet conducting box having the downward angular delivery

page_text: and attached to the furnace door substantially as and for the purposes hereinbefore
described and illustrated in the accompanying drawings.
11. The front air conducting box or plate having the downward angular delivery
and attached to the inside of the furnace front substantially as and for the purposes
5 herein before described and illustrated in the accompanying drawings.
Dated this 2nd day of December 1893.
EDGAR CONISTON MILLS,
Agent to the Applicants.