Improvements in Furnaces.
Year: 1890

page_text: Date of Application, 4th Dec, 1890
Complete Specification Left, 2nd Sept., 1891-Accepted, 3rd Oct., 1891
PROVISIONAL SPECIFICATION.
Improvements in Furnaces.
I, GEORGE FLETCHER, of Masson Works, Litchurch, Derby, in the County of
Derby, Engineer, do hereby declare the nature of this invention (which is, partly
my own invention and has partly been communicated to me from abroad by Donald
Skekel, of Demerara, British Guiana, Engineer) to be as follows:-
This invention relates to improvements in furnaces, and more particularly to
those furnaces which are intended for the consumption of damp fuel, such as sugar
cane megass, or the waste chips from diffusion vessels.
Hitherto, this class of furnace as at present constructed has been ill adapted for
its purpose, by reason of unsuitable design and construction, the fuel being unevenly
distributed over the fire-grate and the supply of air to the burning fuel being so
irregularly distributed that the bulk of the fuel smoulders away, or is carried into
the boiler flues or tubes in the form of soot, so that not only is part of its value-lost
as fuel, but it also clogs the heating surface of the boiler and so retards the trans-
mission of heat. In addition to this defect air passes in large volumes through that
part of the fire-grate upon which there happens to be little or no megass lying, and
this also effects the combustion of the gases evolved from the fuel and necessarily
acts detrimentally upon the boiler itself by reason of the cold air impinging upon
the heated plates.
In order to obviate these defects I propose to make the furnace fire-grate conical
or pyramidal in shape. In the roof or top of the furnace I place the charging
shoot or hopper; the fuel thus introduced into the furnace falls upon the apex or
crown of the fire-grate and being scattered equally upon all sides of the grate
gradually finds its way down the slope towards the base of the cone, the air in the
meantime passes freely through the air-spaces between the bars and thus inter-
mingles with the fuel and allows a thorough combustion to go on. I prefer using
what is known as the "step grate" fire bar in this design of furnace, but the incline
of the cone or pyramid may be altered to suit any pattern of fire-bar that is desired
to be used to suit any particular description of fuel.
The furnace may either be fixed or it may be arranged to revolve slowly. In
this latter case, the fire-grate and the fuel lying thereon are exposed equally and in
turn to the intense heat generated in the hottest part of the furnace and the cooler
gases in the other part, so that the fuel may be evenly and equally consumed on all
Bides of the fire-grate and the iron-work of the same is maintained at a uniform
temperature, the result being that the fuel is economically consumed and the furnace
does not sustain damage through the ironwork being burned.
The charging hopper may be either rectangular or circular in the orifice, and I
prefer to fit the same with valves or doors so arranged and balanced that when a
definite weight of fuel rests upon the doors or valves, the latter open and so
permit the fuel to fall upon the fire-grate, and the doors being thereby relieved of
the load close automatically.
By means of this arrangement the hopper mouth is always closed except when a
charge of fuel is being admitted into the furnace, so that no cold air passes into the
furnace excepting that which is admitted through the fire-grate. The hopper may,
however, be arranged in such a manner that the door or valve is manipulated by the
attendants instead of by the automatic arrangement.

page_text: COMPLETE SPECIFICATION.
Improvements in Furnaces.
I, GEORGE FLETCHER, of Masson Works, Litchurch, Derby, in the County of
Derby, Engineer, do hereby declare the nature of this invention (which is partly
my own invention and has partly been communicated to me from abroad by Donald
Skekel, of Demerara, British Guiana, 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 furnaces, and more particularly to those which are
intended for the consumption of damp fuel such as sugar cane megass or waste
chips from diffusion vessels. This class of furnace, as at present constructed, has
been ill adapted for its purpose by reason of unsuitable design and construction
the fuel being unevenly distributed over the fire grate and the supply of air to the
burning fuel being so irregularly distributed that the bulk of the fuel smoulders
away or is carried into the boiler flues or tubes in the form of soot, so that not only
is part of its value lost as fuel, but it also clogs the heating surface of the boiler,
and so retards the transmission of heat. In addition to this defect air passes in
large volumes through that part of the fire grate on which there happens to be
little or no megass lying, and this also effects the combustion of the gases evolved
from the fuel and necessarily acts detrimentally upon the boiler itself by reason of
the cold air impinging upon the heated plates.
In order to obviate these defects I make the furnace fire grate conical or
pyramidal in shape, the charging shoot or hopper being placed in the roof or top of
the furnace.
I prefer using what is known as the step grate fire bar in this design of furnace
but the incline of the cone or pyramid may be altered to suit any pattern of fire bar
that is desired to be used to suit any particular description of fuel.
The furnace may be arranged to revolve slowly or it may be fixed.
The charging hopper may be either rectangular or circular in the orifice and I
prefer to fit the same with a flap valve or doors, so arranged and counterweighted
that when a definite weight of fuel rests upon the doors or valve, the latter open or
opens and the fuel is thereby allowed to fall upon the fire grate, and the doors
being relieved of their load close automatically. The hopper however may be
arranged in such a manner that the doors or valve are or is manipulated by the
attendant if preferred, instead of by the automatic arrangement.
To enable the invention to be fully understood I will describe how it can be
carried into practice. by reference to the accompanying drawings, in which:-
:-
Figure 1 is a vertical section of a furnace constructed according to my invention,
the fire grate, fitted with ordinary fire bars, being arranged to revolve.
Figure 2 is a plan of the fire grate.
Figures 3 and 4 are similar views to Figures 1 and 2 but shewing my furnace
provided with a stationary fire grate.
Figures 5 and 6 are also similar views to Figures 1 and 2 but shewing a revolving
furnace of my construction in which the fire bars are arranged after the manner of
steps.
Figure 7 is a vertical section of an alternative arrangement of hopper for charging
the furnace.
Similar letters in all the figures indicate similar parts.
a is the fire grate which I make of conical or pyramidal shape as shewn, and
b, bare the fire bars; c is the charging shoot or hopper placed in the roof or top d
of the furnace so that as the fuel is introduced into the furnace it falls on the apex
or crown of the fire grate a and being scattered equally upon all sides of the grate
gradually finds its way down the sides of the slope towards the base of the cone;
the air in the meantime passes freely through the air spaces between the bars, and
thus intermingles with the fuel and allows a thorough combustion to go on.

page_text: When constructing my improved furnace with a revolving fire grate as shewn in
Figures 1 and 2, I provide a spindle e adapted to revolve in a foot step bearing f
Upon this spindle rests and is fixed the centre piece b' of the fire grate with which
the spindle consequently revolves. The centre piece b' supports the upper ends of
the grate bars. g is a hollow circular box or rim which carries the lower end of the
grate bars and which is connected to the spindle e by means of radial arms a¹;
is a circular frame containing rollers i, i upon which the rim g revolves. j is a
pulley or wheel fixed on a shaft k which transmits motion to the fire grate a by
means of a toothed wheel gearing into teeth m fixed on the underside of the
revolving rim g. n represents an air space left all round the furnace; o is a damper
for regulating the supply of air to the underside of the fire grate a. By thus
constructing the furnace to revolve, the fire grate, and the fuel lying thereon are
exposed equally and in turn to the intense heat generated in the hottest part of the
furnace and the cooler gases in the other part, so that the fuel may be equally and
evenly consumed on all sides of the fire grate, and the ironwork of the same is
maintained at a very even temperature, the result being that the fuel is economically
consumed and the furnace does not receive any damage through the ironwork being
burned.
p, p, Figure 1, are the flaps or doors with which I prefer to provide the charging
hopper c, the said doors being hinged to the hopper at 7, 7. r, are the counter-
weights of the flaps or doors p, p which are so regulated as to open under a given
weight of fuel introduced through the top of the furnace and to close automatically
directly the fuel is discharged onto the fire grate a. By this arrangement the
hopper mouth is always kept closed except when a charge of fuel is being
admitted into the furnace, so that no cold air passes into the furnace except that
which passes through the fire grate.
The hopper may, if desirable, be placed much higher in the furnace roof than it
is shewn in the drawing, in order to keep it clear of the fierce heat generated in the
furnace.
When constructing my furnace with a fixed or immovable fire grate, as shewn in
Figures 3 and 4, I support the central pillar e, which in the furnace with a revolving
grate formed the spindle, and upon which the fire grate rests, upon a beam or
girders having its ends embedded in the sides of the furnace. The upper ends of
the fire bars, which are shewn of ordinary construction, are supported by the centre
piece carried by the pillar a, and the lower ends are carried on a fixed ring c¹
connected to the pillar a by means of radial stays d¹.
The charging hopper c, Figure 3, is shewn fitted with a valve t designed to be
opened and closed by hand for the purpose of excluding the air when fuel is not
being introduced into the furnace.
26
Figures 5 and 6 shew my revolving furnace having the bars b, b of the
fire grate arranged in steps as shewn in Figure 5 and made in segments as
shewn in Figure 6, which segments are bolted to plates extending radially
from and supported at their upper ends by the centre piece b¹ of the
furnace, their lower ends resting upon the hollow circular box or rim 9,
constructed and arranged to be operated similarly to the rim of the revolving
furnace shewn in Figure 1. The charging hopper c is shewn without the valve or
doors hereinbefore described but fitted with a helical screw v, driven by bevel-
gearing for the purpose of giving a continuous and regular feed of the fuel.
Figure 7 represents a modified arrangement of the feeding hopper c in which
rollers , are employed to facilitate the feeding of the fuel.
These rollers may
be arranged to be adjusted by means of a set screw . P is the hinged and counter-
weighted flap or door for automatically closing the hopper.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what I
claim is :-
1. A furnace having a conical or pyramidal revolving or fixed fire grate and a

page_text: charging shoot or hopper in the roof or top of the furnace, substantially as herein-
before described.
2. A circular revolving furnace having a conical or pyramidal fire grate, the
said fire grate being fitted with a spindle and with a centre piece for supporting
the upper ends of the grate bars, and a circular box or rim driven by: gearing
and serving to support the lower ends of the grate bars, substantially as herein-
before described and illustrated in Figures 1 and 2 of the accompanying
drawings.
3. A furnace having a conical or pyramidal fire grate fitted with a supporting
pillar and centre piece for carrying the upper ends of the grate bars, the lower
ends of the bars being carried on a fixed ring, substantially as described.
4. A furnace having a conical or pyramidal fire grate of stepped bars, sub-
stantially as hereinbefore described.
5. The construction and use of the improved furnaces herein before described
and illustrated in Figures 1 and 2, Figures 3 and 4, and Figures 5 and 6 of
the accompanying drawings.
6. The combination with a furnace having a conical or pyramidal fire grate,
of a charging hopper fitted with automatically closing flaps or doors or with
valves designed to be opened and closed by hand for the purpose set forth and
substantially as hereinbefore described with reference to Figures 1 and 3
respectively of the accompanying drawings.
7. The combination with a furnace having a conical or pyramidal fire grate
of a charging hopper fitted with a helical screw driven by gearing for the
purpose set forth and substantially as hereinbefore described and illustrated in
Figure 5 of the accompanying drawings.
8. The combination with a furnace having a conical or pyramidal fire grate
of a charging hopper having rollers fitted beneath an automatically closing flap
or door, substantially as hereinbefore described and illustrated in Figure 7 of
the accompanying drawings.
Dated the 2nd day of September 1891.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.