Improvements connected with Mechanical Stokers and Furnaces.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements connected with Mechanical Stokers and Furnaces.
Wē, JAMES JONES MELDRUM, THOMAS-FREDERICK MELDRUM, JOHN WESLEY
MELDRUM, and FRED CLAYTON, all of Atlantic Works, City Road, Manchester, in
the County of Lancaster, Engineers, do hereby declare the nature of this invention
to be as follows:
-
This invention has reference, mainly, to mechanical stokers, that is, apparatus
and means for feeding solid fuel to, and burning it in furnaces of steam generators,
and other plant or apparatus in which fuel is similarly burned, and the type of
such apparatus to which the invention mainly relates, is that in which the fuel
is piled up and coked, at the front portion when it is first introduced. It has,
however, also reference in part to furnaces whether fired mechanically or by hand,
in which air supplied to the furnaces for the combustion of the fuel is artificially
supplied, that is, where the draft is forced.
The object and effect of the present invention is, mainly, to provide improve-
ments in connection with furnaces, by which the coking of the fuel piled up in front
near the point of introduction, is better performed, or its uniform combustion is
rendered more sure; to effect a more uniform and better combustion of the fuel
generally; to render the efficiency of mechanical stokers uniform and relatively
high under different conditions of working, and different degrees of care and
attention; and to generally improve the working of stokers as hereinafter described.
According to this invention, in a stoker of the coking type, in which the fuel is
first fed and piled up near the point of introduction, and coked in this position,
air is supplied to and passed through the pile of fuel, and such air is supplied
under a pressure exceeding that in the ashpit for burning the fuel on the grate
proper. If the pressure of air supplied to, or existing in the ashpit is above that
of the atmosphere, then that supplied to the front of the furnace to pass through
the pile of fuel being coked, will be at a pressure again exceeding this. The air
is supplied by any suitable means.
In some cases with coking stokers there is employed in connection with and
below a perforated coking plate on which the fuel being coked or ignited rests,
a dead plate with a chamber or space between them, this chamber or space being
supplied with air under pressure from the hollow front, or otherwise.
This or an equivalent arrangement or combination of a hollow chamber having
a perforated top and a closed bottom, and supplied with air under pressure, may
be applied with other types of stokers than coking stokers and with hand-fed
furnaces; and it is applicable where the ashpit is open to the atmosphere, as well
as where closed and supplied with air under pressure. It is also applicable where
artificially induced draught is employed, as by an exhaust fan, or other mechanical
apparatus.
In some cases, this chambered coking front or plate may be arranged and
adapted to move backward and forward in such a manner as to assist in feeding
the fuel forward on to the bars.
:
This chambered coking plate may, further, in some cases, be constructed to
rise and fall, in whole or in part, in addition to the backward and forward motion,

page_text: or instead of same. This vertical motion assists in breaking up or opening the
fuel.
:
In addition to the vertical motion above referred to, the upper or perforated
plate of these parts, arrangement, or combination, is preferably made so that it
may be raised from the lower or dead plate, to allow of the removal of any ash
or other matter falling through the slots or perforations. The lower or dead plate
of the combination will rest on or near the bars, whether moving or fixed.
According to a modification, in a mechanically fed coking stoker, there is pro-
vided in connection with the furnace front, below the ram or other fuel feeding
device, a separate or independent chamber or box, or chambers or boxes, into
which air of higher pressure to be forced through the fuel being coked, is supplied;
such air being supplied to the box or chamber either directly, or by way of the
hollow front; and this chamber will be provided with a door externally, such as
a hand firing door, and an internal upright grate or baffle, through which the air
for combustion is forced.
.
Further, in mechanical stokers of the coking type, as referred to, air under
pressure is supplied through the fuel, in the front of the furnace, being coked,
and into the ashpit and through the fuel bearers, independently; the pressure of
each service of supply being separately adjustable by suitable adjusting devices.
Thus in a stoker of the type in which air for the combustion of fuel is supplied
under a pressure greater than that of the atmosphere, that supplied to the fuel
in front, and being coked, is passed directly to it, and not first through or by way
of the ashpit, and then to the furnace front.
According to a further feature or modification in stokers of the coking type;' às
herein referred to, a furnace is provided with a hollow front, and into this hollow
front the air for combustion is forced; and from this air a portion is drawn and
passed through the pile being coked, inside the front; while another portion is
supplied over the fire, as secondary air for supporting or promoting combustion
of the unburnt, or partly burnt, gases, given off from the fuel.
And in connec-
tion with this feature, viz., in connection with a furnace having a hollow front,
this front is cooled, and kept at such a temperature, as will preserve the metal
against burning by the fire, inside, or prolong its life, by passing and forcing the
air used in the combustion of the fuel, into and through chambers or conduits' in
this front, and thence into a closed ashpit of the furnace. In some cases, when
desired, a part of this air is supplied as secondary air to the furnace, over the
fuel.
According to a further feature, in furnaces mechanically fired, or hand fired,
in which air for burning the fuel is artificially supplied or forced, the furnace
front is hollow, and a steam jet air supplying or forcing apparatus, of any known
suitable type (and arranged, say, parallel with the furnace front), is fitted by its
discharge or delivery end to the hollow front, and discharges or forces the air
supplied by it, into and through the front, and then downwards or into a closed
ashpit; or partly to the ashpit, and partly to the furnaces above the fuel. as
secondary air.
It is to be understood that the different novel features or characteristics of the
invention or improvements herein described, may be employed separately, in
connection with furnaces or stoking apparatus, as well as in different combinations,
accordingly as their application or employment may be serviceable or advantageous,
or as may be desired. And, as regards the forms and constructions of the parts,
these will be varied and modified, necessarily, in the application of the invention
to different types or kinds of furnaces, and to meet various requirements, or special
cases.

page_text: COMPLETE SPECIFICATION.
Improvements connected with Mechanical Stokers and Furnaces.
We, JAMES JONES MELDRUM, THOMAS FREDERICK MELDRUM, JOHN WESLEY
MELDRUM, and FRED CLAYTON; all of Atlantic Works, City Road, Manchester, in
the County of Lancaster, Engineers, 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;-
This invention-has-reference, mainly, to mechanical stokers, that is, apparatus
and means for feeding solid fuel to, and burning it in furnaces of steam generators,
and other plant or apparatus in which fuel is similarly burned; and the type of
such apparatus to which the invention mainly relates, is that in which the fuel is
piled up and coked, at the front portion,, when it is first introduced.... It has,
however, also reference in part to furnaces, whether fired mechanically or by hand,
in which air supplied to the furnaces for the combustion of the fuel is artificially
supplied, that is, where the draft is forced.
The objects and effects of the present invention are, mainly, to provide improve-
ments in connection with furnaces, by which the coking of the fuel piled up, in
front near the point of introduction, is better performed, or more rapidly effected,
or its uniform combustion is rendered more sure; to effect a more uniform and
better combustion of the fuel generally; to render the efficiency of mechanical
stokers uniform and relatively high, under different conditions of working, and
different degrees of care and attention; and to generally improve the working of
stokers, as hereinafter described.
'
1..
#
According to this invention, in a 'stoker of the coking type, in which the fuel is
first fed and piled up near the point of introduction, and coked in this position,
air is supplied to and passed through the pile of fuel; and such air is supplied
under a pressure exceeding that in the ashpit for burning the fuel on the grate
proper. If the pressure of air supplied to, or existing in the ashpit be above that
of the atmosphere, then that supplied to the front of the furnace to pass through
the pile of fuel being coked, will be at a pressure again exceeding this. The air
is supplied by any suitable means.
זי
**
In some cases, with coking stokers, there is employed in connection with, and
below a perforated coking plate on which the fuel being coked or ignited rests,
a dead plate with a chamber os, space between them, this chamber: or space being
supplied with air under pressure from a hollow front, or otherwise.
.
This or an equivalent arrangement or combination of a hollow.chamber, having
a perforated top and a closed bottom, and supplied with air under pressure, may be
applied with other types of stokers than coking stokers, and with hand-fed
furnaces;. and it is applicable where the ashpit is open to the atmosphere, as
well as where closed and supplied with air under pressure. It is also applicable
where artificially induced draught is employed, as by an exhaust fan, or other
mechanical apparatus.
In some cases, this chambered coking front or plate may be arranged and
adapted to move backward and forward in such a manner as to assist in feeding
the fuel forward on to the bars.
This chambered coking plate may. further, in some cases, be constructed to rise
and fall, in whole or in part, in addition to the backward and forward motion,
or instead of same. This vertical motion assists in breaking up or opening the
fuel.
In addition to the vertical motion above referred to, the upper or perforated
plate of these parts, arrangement, or combination. may be made so that it may be

page_text: raised from the lower or imperforate plate, to allow of the removal of any ash or
other matter falling through the slots or perforations.
According to a modification, in a mechanically fed coking stoker, there is
provided in connection with the furnace front, below the ram or other fuel feeding
device, a separate or independent chamber or box, or chambers or boxes, into which
air of higher pressure to be forced through the fuel being coked, is supplied; such
air being supplied to the box or chamber, either directly, or by way of the hollow
front; and this chamber will be provided with a door externally, such as a hand
firing door, and an internal upright grate or baffle, through which the air for
combustion is forced.
Further, in mechanical stokers of the coking type, as referred to, air under
pressure is supplied through the fuel, in the front of the furnace, being coked,
and into the ashpit, and through the fuel on the fuel bearers, independently;
the pressures of each service of supply being separately adjustable by suitable
adjusting devices. Thus, in a stoker of the type in which air for the combustion
of fuel is supplied under a pressure greater than that of the atmosphere, that
supplied to the fuel in front, and being coked, is passed directly to it, and not first
through, or by way of, the ashpit, and then to the furnace front.
According to a further feature or modification, in stokers of the coking type, as
herein referred to, a furnace is provided with a hollow front, and into this hollow
front the air for combustion is forced; and from this air, a portion is drawn and
passed through the pile being coked, inside the front; while another portion is
supplied over the fire, as secondary air for supporting or promoting combustion
of the unburnt, or partly burnt, gases, given off from the fuel. And in connec-
tion with this feature, viz., in connection with a furnace having a hollow front,
this front is cooled, and kept at such a temperature, as will preserve the metal
against burning by the fire, inside, or prolong its life, by passing and forcing the
air used in the combustion of the fuel, into and through chambers or conduits
in this front, and thence into a closed ashpit of the furnace. In some cases, when
desired, a part of this air is supplied as secondary air to the furnace, over the fuel.
According to a further feature, in furnaces mechanically fired, or hand fired, in
which air for burning the fuel is artificially supplied or forced, the furnace front
is hollow, and a steam jet air supplying or forcing apparatus, of any known
suitable type (and arranged, say, parallel with the furnace front), is fitted by its
discharge or delivery end to the hollow front, and discharges or forces the air
supplied by it, into and through the front, and then downwards or into a closed
ashpit; or partly to the ashpit, and partly to the furnaces above the fuel, as
secondary air.
It is to be understood that the different novel features or characteristics of the
invention or improvements herein described, may be employed separately, in
connection with furnaces or stoking apparatus, as well as in different combina-
tions, accordingly as their application or employment may be serviceable or
advantageous, or as may be desired. And, as regards the forms and construc-
tions of the parts, these will be varied and modified, necessarily, in the application
of the invention to different types or kinds of furnaces, and to meet various
requirements, or special cases.
In the drawings hereto annexed, which we will now describe, the constructive
characteristics hereunder are shewn applied; and in connection with these examples
the improvements, as regards the methods or modes of effecting the combustion
of the fuel, and other features, will be exemplified & set forth.
In these drawings, Figure 1 is a sectional elevation; and Figure 2 is a front
elevation, illustrating our improvements connected with the coking of fuel burnt
in furnaces, as it is introduced, and prior to the direct combustion of solid carbon
upon the grate proper; and also certain other improvements.
.
Figure 3 is a sectional elevation shewing a modified construction of parts for
carrying out the improvements referred to in connection with Figure 1.

page_text: Figure 4 is a plan in section taken at A. A Figure 1.
Referring, in the first instance, to Figures 1 and 2, these drawings shew a
mechanical coking stoker, in which the air supplied to the part of the fuel being
coked, and that supplied through the bars for direct combustion of the coke so
made at the back of the grate, are separately supplied; and this supply is effected
by steam jet air blowers. In the drawings, a represents the fuel hopper, and b is
a vibrating feeding plunger for supplying fuel from a to the front of the furnace;
being its operating engine or motor. c is the front plate of a steam generator,
and represents the furnace. d is one of the fire bars, which, in this case, are
movable, and d is the operating shaft for moving the bars.
The upper part of the apparatus, that is the part above the level of the bars d
fitted to the front, c, consists of a hollow cast box front e, with an aperture 6¹
through it from the front to the back, in front of the fuel feeder b; and an aperture
or doorway f. about the main door j; and there are openings through the metal
forming the front of the box e, as hereafter described, by which this front box
communicates with the doorway f, and air is admitted to it. The air is supplied
by the steam jet blower h, into the hollow front, through an opening at the top.
Then in the front of the doorway f, and in a part of the front box e. there is another
bax i which encloses the doorway f, and also the openings in the front plate of
the box e, which make the communications between e and f. In a line with the
openings in the back plate of the box e. are openings el, and also grid open-
ings in the plate e³. which is fitted on the inner face of the box e; and through
these openings e¹ and grids e, the air from e will pass through the fuel piled up
in front of the box, and being under the operation of coking.
Within the box e there is a door ; hinged at ¹, having a perforated face ³,
with a removable perforated inner face thereon and this projects inwards to a
point in line, or nearly in a line, with the face of the plate 3; and on the outside
of the box there is a door opposite the doorway f. and connected with the
door by a link. There are also openings covered by doors, on each side.
opposite the openings. Through the openings in the door j, the air passes from
the box to the pile of fuel in front of it, and effects the coking action; and
through this doorway, also, access to the interior of the furnace is obtained for
cleaning the grate, or other purpose; while by the doors, the openings can
be got at from the front for any purpose, and the fire attended to.
The dead plate or coking plate-which is designated on to which the fuel
from the feeder 6 is delivered, and on which it is coked, is perforated as shewn ;
and air at a pressure exceeding that in the ashpit is supplied through these perfora-
tions. To supply air to this pressure a chamber is formed below the plate k. by
the plate below it, extending from the bottom plate of the box i. to the front
end of k, and by having the inner end of the plate k, itself, standing above the
bottom of, so that air is admitted direct from the box i to this space or chamber
beneath k.
Hence both the air supplied through the perforated parts 73 and es into the fuel,
and that supplied through the perforated coking plate k, are at a pressure exceed-
ing that in the ashpit.
m generally designates the ashpit of the furnace c¹; and n is a hox enclosing
the end of this ashpit, and the ends of the fire bars d; and the front of this box
may be in about the same plane as the box i. In this box n there are open-
ings n to the edges of the metal about which the heads of the horizontally
disposed steam jet blowers o, supplying air to the ashpit, are attached; and an
opening below, normally covered by the door nt, for clearing out the ashpit of
ashes, etcetera.
Opposite the shaft and the ends of the fire bars there are openings n³, covered
by the doors n³, for gaining access to these parts.
The air supplied by the blowers o into the ashpit m, as stated, will be at a
lower pressure than that existing in the front e; and this air from the ashpit has

page_text: access only to the coked fuel which lies on the bars & beyond the end of the coking
plate k.
With regard to this chamber or space below the coking plate k, and the supply
of air at a pressure above the atmosphere, they may be applied to other types
of stokers than coking stokers, and also with hand fed furnaces; and it is
applicable where the ashpit is open to the atmosphere, as well as where closed
and supplied with air under pressure. It is also applicable where artificially
induced draft is employed, as by an exhaust fan or other mechanical apparatus.
This plate is also shewn in the drawings adapted to be moved up and down
automatically, and by which the fuel is broken up and opened, and the feeding
'from it on to the bars is assisted. This movement is effected by the employment
of a wedge or inclined plane on the under surface, at either side of the plate,
and oppositely inclined planes on certain of the bars d; whilst the front part
of the plate is provided with hinge pins , which rest in suitable sockets in the
box c. In action, as the bars bearing the inclined planes are moved backwards,
these inclines come in contact with ¹ and lift the plate k; and then in their
return motion, they move away from ¹, and allow the plate to again fall on to
the bottom plate 7. This plate 7 has a slot in it at parts where the inclines
come to allow this motion; or it may move with the bars d.
In Figure 3, the modification of the air chamber below the plate k, and the
mode of actuating this plate, are illustrated.
In this case, the fire bars d are provided with projections at one end, 'so that
they practically touch each other at these parts; and the plate p, and plate q—
which is hinged at gl-together with the fire bar supporting plate p', close the
space between the grids of the bars d, and the front part of the box n. The
air from the box e has access through the chamber thus formed, and so through
the bottom of the fuel on the coking or dead plate k.
The dead platek, in this case, is adapted to be moved longitudinally in order
to break up and open the fuel on it; and it is effected by providing a projection
on the upper side of say two of the bars d, and projections ³ on the underside
of k, so that the movements of the bars d, they will come in contact with the
projections ; and move the plate & to and fro. "The sockets in this case for the
pins are elongated to allow of this movement.
By the plate q being hinged at g¹, dust, etcetera, which may fall through the
opening of the plate k; may, by moving it about its hinge downwards; be dis-
charged into the ashpit below.
In some cases, the plate k may be adapted, by means of the inclined planes d³,
and (Figure 1) and the hinge pins 2, and slotted sockets, to receive both an
up and down, and also a longitudinal to and fro movement.
In the accompanying drawing, the ashpit is shewn provided with air supply-
ing means distinct from that for supplying air to the fuel above the bars on the
plate ; but in some cases, the air supplied to the ashpit may be taken from that
delivered by the air supplying means, delivering its air into the box e; such air
being conveyed by a suitable conduit connecting the box e, with the ashpit, and
having upon it a suitable regulating valve, by which the respective pressures in
the ashpit and the box can be regulated to those required.
A sight or poking hole. is provided through the hopper a, and above the fuel
feeding device b. This is effected by providing a bridge piece ŕ, extending through
the hopper, just above the fuel feeding device b, and a door-way and door !,
on the hopper front. A bridge piece passes through the front box e, and
separates it from the fuel inlet aperture 6'; and the space below the bridge
piece r.
'
Air—generally called "secondary air," may be supplied to the furnace above
the fuel from the box e, in regulated quantities, as through the poking hole
below the bridge.piece 2, or any openings in the inner plate of the box, having
regulating devices in connection with them.

page_text: Having now particularly described and ascertained the nature of this inven-
tion, and in what manner the same is to be performed, we declare that what
we claim is:-
1. The herein described method of effecting the combustion of fuel in mechani-
cally fed furnaces, consisting in effecting the coking of the fresh fuel supplied
to the grate or fuel bearers, by air supplied to it at a pressure exceeding that
supplied to the coked fuel for completing the combustion thereof, subsequently;
for the purposes set forth.
2. The herein described method of effecting the combustion of fuel in mechani-
cally fed furnaces, consisting in the coking of the fresh fuel supplied to the grate
or fuel bearers, by supplying air artificially to it, and by effecting the subsequent
combustion of the coked fuel by a distinct quantity of air artificially supplied to
it; for the purposes set forth.
3. The herein described method of effecting the combustion of the fuel in
mechanically fed furnaces, consisting in the coking of the fresh fuel supplied
to the grate or fuel bearers, by supplying air artificially to it at a pressure exceed-
ing that employed for the combustion of the coked fuel; and by effecting the
subsequent combustion of the coked fuel, by a distinct quantity of air artificially
supplied to it; for the purposes set forth.
4. The herein described improvement connected with the combustion of fuel
in mechanically fed furnaces, consisting in effecting the coking of the fresh fuel
supplied to the grate or fuel bearers by air separately supplied to it by suitable
artificial air supplying means; for the purposes set forth.
5. In a furnace stoking apparatus of the coking type, a chamber below the
surface onto which the fuel is fed, and separate from the ashpit; and from which
air at a pressure exceeding that in the ashpit is discharged into said fuel; sub-
stantially as set forth.
6. In a furnace, a perforated plate onto which the fresh fuel is fed, having a
chamber below it, open to said plate, said chamber being out of communication
with the ashpit below, and connected with a source of artificial air supply; for
the purposes set forth.
7. In a furnace in which the fuel is coked prior to complete combustion, a
perforated plate onto which the fresh fuel is fed, and a perforated front between
the fuel feeding device and said plate, having a chamber behind and below same,
respectively, to which air is artificially supplied, and being out of communication
with the ashpit of the furnace; substantially as set forth.
8. In a coking stoker in which the air for effecting the combustion of the fuel
is artificially supplied, supplying all the air used for combustion into and by a
hollow front (such as e), and conducting part of such air through apertures in the
front behind or below, or behind and below, the pile of fuel being coked, for
effecting the coking action, and the residue to the ashpit through a regulated
opening for effecting the combustion of the coked fuel; substantially as set forth.
9. In a furnace in which the fuel is coked prior to complete combustion, a
hollow box front e, connected with a source of artificial air supply; an opening f
below the front of fuel supply; a chamber i in communication with e; and a
perforated body in said opening, through which air from the chamber i passes to
the furnace; substantially as set forth.
10. In a furnace in which the fuel is coked prior to complete combustion, a
hollow box front e connected with a source of artificial air supply; a doorway f;
a chamber i communicating with e; a perforated door in the doorway f; and a
door oni in front of the door j; substantially as set forth.
11. In a furnace coking stoking apparatus, a coking plate k, onto which the
fuel is fed and piled in the front of the furnace, in combination with moving
fire bars d below, and adapted to be moved by said bars when moving; sub-
stantially as set forth.
12. The arrangement and construction of the parts constituting the air supplying

page_text: means to the fuel at the front of the furnace; as set forth with reference to and
shewn in the drawings.
13. The arrangement and construction of the parts constituting the chamber
below the coking plate as set forth with reference to and shewn in the drawings.
14. The arrangement and construction of parts constituting the means for
operating the coking plate; as set forth with reference to and shewn in the
drawings.
Dated this 24th day of October 1899
CHEESBROUGH & ROYSTON,
Applicant's Patent Agents, 15, Water Street, Liverpool.