Improvements in and relating to Furnace Fire-grates.
Year: 1890

page_text: Date of Application, 25th Oct., 1890
Complete Specification Left, 24th July, 1891-Accepted, 29th Aug.,
1891
PROVISIONAL SPECIFICATION.
Improvements in and relating to Furnace Fire-grates.
I, ARTHUR CHARLES AUDEN, of the Unity Iron Works, Baker's Row, in the
County of London, Works Manager of the Hopcraft Furnace Company Limited,
do hereby declare the nature of this invention to be as follows:-
The object of this invention is to construct a furnace, with means of mechanical
stoking, which will effect more complete combustion of the fuel than in ordinary
furnaces, thus enabling small cual, slack, or coal dust to be burnt with good results.
The furnace also is so constructed as to be practically automatic in its action,
so far as the stoking, feeding, and cleaning of the clinker from the bars are
concerned.
The furnace is provided with reciprocating fire-bars constructed in such a manner
as to facilitate the introduction of fuel from below, and to provide for one or any of
them being taken away from the grate and a new bar substituted in a more con-
venient manner than heretofore. The fire-bar also is constructed so as to work the
incandescent fuel along its length in a more efficient and regular manner than with
the reciprocating bars at present in use. A further object in the construction of
these fire-bars is to provide means for lubricating their front ends, so as to minimise
the friction and wear of the parts.
The upper surface of the fire-bars is formed with steps upwards at the front and
bevelled off towards the rear. The front end of the bar is secured by a stud to a
short extension arm journalled on a cam-shaft, supported in brackets outside the
front of the furnace, which said cam-shaft is rotated by any suitable means. When
a bar is burnt or otherwise rendered useless, the stud nut, which is easily accessible
from the front of the ashpit, is unscrewed and the bar allowed to fall into the ash-
pit from whence it may be removed, and a new bar substituted and secured in
position on the short extension arm.
The furnace may be worked with forced, induced, or natural draught, as found
convenient, although I prefer to use forced draught distributed in the manner
described in the Specification of my application for Patent entitled "Improve-
ments relating to the distribution of forced draught in furnaces" of even date
herewith.
The fuel is fed by a screw conveyor or conveyors preferably constructed like
those employed in the Hopcraft furnace, a description of which will be found in
the Specification of a Patent granted to Lewis Hopcraft, numbered 2581 and dated
February 13th 1889 but working horizontally and actuated by the main shaft, from
which also motion is, by preference, transmitted by suitable gearing to the cam-
shaft working the reciprocating bars.
The fuel is deposited on the fire-bars which take it up and pass it along in a
regular manner to the rear where the clinker and other unconsumed products fall
through an aperture in front of the bridge into the ashpit below, whence they may
be removed when necessary. Each conveyor is provided with disengaging clutch
mechanism so that the feed may be discontinued at any time without stopping the
reciprocation of the bars. By this means when it is required to discontinue the
feed from any cause the conveyor tubes are left full of coal and hence are not liable
to be burnt by the fire on the grate while, at the same time the bars are kept moving
and prevent the formation of clinker.
Saaho 1000
CASTLE SMITH,
"Invention" Office, 54, Fleet Street, London, E.C.,
Agent for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in and relating to Furnace Fire-grates.
1, ARTHUR CHARLES AUDEN, of the Unity Iron Works, Baker's Row, in the
County of London, Works Manager of the Hopcraft Furnace Company Limited,
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:-
The object of this invention is to construct a furnace with means of mechanical
stoking, which will effect more complete combustion of the fuel than in ordinary
furnaces, thus enabling small coal, slack, or coal dust to be burnt with good results.
The furnace also is so constructed as to be practically automatic in its action,
so far as the stoking, feeding, and cleaning the clinker from the bars are
concerned.
The furnace is provided with moving fire-bars constructed in such a manner as
to allow for one or any of them being taken away from the grate and a new bar
substituted in a more convenient manner than heretofore. The fire-bar also is
constructed so as to work the incandescent fuel along its length in a more efficient
and regular manner than with the moving bars at present in use. A further object
in the construction of these fire-bars is to provide means for lubricating their front
ends, so as to minimise the friction and wear of the parts.
The fuel is fed by a screw conveyor or conveyors and deposited in the front of
the fire-bars which take it up and pass it along in a regular manner to the rear
where the clinker and other unconsumed products fall through an aperture in
front of the bridge into the ashpit below whence they may be removed when
necessary.
And in order that my invention may be more fully understood and carried into
practice, I will now proceed to describe the same with reference to the accompanying
drawings in which similar letters are used to indicate corresponding parts in all the
figures.
Figure 1 is a longitudinal section of a furnace made in accordance with this
invention;
Figure 2 is a front elevation and Figure 3 is a part side elevation of the
same.
I will describe the construction and manner of fitting and actuating one of the
moving fire-bars and as all are alike the description of one of them will answer
for all.
The upper surface of the bar is sloped upwards at the front as shown at A
Figure 1, and is bevelled off towards the rear in one or more steps B. The rear
end of the bar rests upon a fixed bearer C running transversely across the fire-
grate.
The front end of the bar is provided with a lug or projection D fitting into a
socket or recess in a short extension arm E to which the bar is secured by means of
a stud or bolt F fastened to the extension arm E and passing through a suitable
hole in the bar. The end of the stud or bolt F is provided with a nut G. When
a bar is burnt or otherwise rendered useless, the nut G, which is easily accessible
from the front of the ashpit, is unscrewed and the bar allowed to fall into the
ashpit, from whence it may be removed and a new bar of similar construction
substituted, and secured in position on the short extension arm E. The forward
end of the said exteusion arm E is bifurcated and hollowed or curved so as to fit
snugly round the semi-circumference of the cam shaft H, the cheek piece or
bearing J being curved to fit the other semi-circumference of the shaft, the whole
being secured together by the nuts K on the threaded ends of the bifurcations, the
faces of said nuts K bearing against the flat face of the cheek piece or bearing J
which is thus kept in position. The extension arm E is thus journalled on the cam

page_text: shaft H, lubrication being provided for by the oil duct or channel L in the bearing J.
The cam shaft, extension arm and bearing, are accessible from the outside of the
furnace through the sliding door M.
The cam shaft is supported by the end plates N (see Figure 3) or by suitable
brackets on the outside of the furnace and is preferably rotated in the following
manner-Keyed on each end of the cam shaft H is a worm wheel O gearing with
a worm P on a short shaft Q journalled in a bracket R bolted or otherwise secured
to the furnace front. Keyed on the forward end of the shaft Q is a worm wheel S
gearing with a worm on the main shaft T which is driven by any suitable motive
power. To avoid complication the means for supporting and actuating the cam-
shaft are not shewn in Figure 2. As before stated the cam-shaft is preferably
actuated by the gearing shewn in Figure 3 but equivalent means for transmitting
the motion from the main shaft T may be adopted or the rotation of the cam-shaft
may be effected independently of the main shaft as required by circumstances.
As shewn in Figure 2, the main shaft T is provided with two worms U. When
the power for rotating the cam-shaft H is transmitted from the main shaft these
worms U are loose on the main shaft to which they may be clutched by clutch
blocks sliding on feathers on the main shaft in the ordinary manner. The worms U
gear with worm wheels V keyed on the conveyor shafts W, and may be thrown
out of gear by the disengaging clutch mechanism so that the feed may be discon-
tinued at any time without stopping the movement of the bars. By this means
when it is required to discontinue the feed from any cause the conveyor tubes X
are left full of coal, and hence are not liable to be burnt by the fire on the grate,
while at the same time the bars are kept moving and prevent the formation of
clinker. It will be understood that this clutch mechanism is not required when the
cam-shaft is driven independently of the main shaft T.
If desired the upward and downward movement of the bars may be dispensed
with and the bars made to move longitudinally backwards and forwards only by any
suitable and well-known arrangement of mechanism, in which case the bars in long
furnaces may be supported by rollers fixed in suitable positions and running trans-
versely across the fire-grate.
The furnace may be worked with forced, induced, or natural draught as found
convenient although I prefer to use forced draught distributed in the manner
described in the Specification of my application for Patent entitled "Improvements
relating to the distribution of forced draught in furnaces" of even date herewith
and numbered 17087 of 1890.
To feed the fuel two conveyors are preferably used one at each side of the
hopper Y the conveyor tube X being curved slightly upwards so as to cause an
equal distribution of the fuel on to the front of the grate. The conveyors are
arranged beneath the hopper Y and .have a slight slope or curve upwards corre-
ponding to the curve of the conveyor tube X the screw being made in sections
articulated or jointed together like those employed in the Hopcraft furnace, a
description of which will be found in the Specification of a Patent granted to
Lewis Hopcraft numbered 2581 and dated February 13th 1889. The fuel as it
falls from the hopper Y is therefore worked along the slightly upward curved
conveyor tube X and deposited on the front of the moving bars, the motion of which
in conjunction with the feed of the conveyor causes the fuel to travel along towards
the rear of the grate.
The complete arrangement of the furnace fire-grate is such that should any of
the mechanical appliances get out of order, hand firing can be immediately resorted
to. To effect this it is only necessary to remove the hopper. Other mechanical
stokers at present in use do not allow of hand-firing in similar circumstances, but
require that the boiler should be stopped and the fire extinguished wherever any of
the mechanical appliances are out of working order.
By the sloping of the fire-bars upwards at the front there is less back heat
towards the fire door than in other furnaces worked with forced, induced, or natural
draught.

page_text: 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 I
claim is :-
(1) The manufacture and use of a furnace fire-bar detachably secured at its
forward end to a short extension arm allowing for the removal of the bar and the
speedy substitution of another bar substantially as described.
(2) A moving fire-bar made in two sections detachably secured together, the
rear section having steps or bevels B, and the front section being actuated by a
rotating cam-shaft whereby the movement of the bar is effected substantially as
and for the purposes hereinbefore set forth and illustrated in the accompanying
drawings.
(3) The combination of the various parts forming my improvements in and
relating to furnace fire-grates arranged and operating substantially as described
and for the purpose stated.
CASTLE SMITH,
Invention" Office, 54, Fleet Street, London, E.C.,
Agent for the Applicant.
CASTLE SMITH,
"Invention" Office, 54, Fleet Street, London, E.C.,
Agent for the Applicant.