Improvements in Steam Generator and other Furnaces, and in Apparatus for Supplying Dust or Pulverulent Fuel thereinto.
Year: 1892

page_text: Date of Application, 14th May, 1892
Complete Specification Left, 14th Mar., 1893-Accepted, 13th May, 1893
PROVISIONAL SPECIFICATION.
Improvements in Steam Generator and other Furnaces, and in
Apparatus for Supplying Dust or Pulverulent Fuel thereinto.
I CHARLES CROFTON BLACK of Hill House, Buckhurst Hill in the County of
Essex, Salesman, do hereby declare the nature of this invention to be as
follows:-
This invention relates to the construction of steam generator and other furnaces
in which pulverulent fuel, such as coal dust and the like is employed, and of
apparatus whereby the said fuel is conveyed, either automatically, or by other
means from a suitable source of supply and delivered by means of jets of air or
steam, or of both combined into the said furnace and there burned, and has for its
object to more effectually utilize the heat of combustion; to admit of readily
collecting the residual products of such combustion; to regulate the supply of fuel
according to the working requirements and to deliver it into the furnace in a
condition most favourable for its complete combustion.
In a furnace constructed according to this invention the grate consists of a basin
shaped structure of fire clay, fire brick or other refractory material sloping down-
wards from the rear part to the front of the furnace to facilitate the withdrawal of
deposit, and being. fitted with a suitable opening for this purpose.
In an apparatus for supplying the fuel to the furnace the pulverulent fuel is
first conveyed by any ordinary means such as a creeper band, helical worm, or
other conveyer to a hopper and thence to an injecting apparatus by which it is
delivered into the furnace.
The mode of conveying the fuel from the above mentioned hopper to the
injecting apparatus is by means of an endless ribbed creeper band, rotary helical
worm, rotary screw blade or other suitable conveyer. When a creeper band.
conveyer is employed rotary brushes are provided for removing the fuel from it on
its arrival at the injecting apparatus, and the amount of the feed is regulated by an
adjustable damper placed in the path of the band. When a helical worm conveyer
is employed the worm is constructed with variable pitch increasing from its initial
or starting end, and is encased in a cylindrical rotary sleeve or casing having blades
on its extremity for the purpose of agitating the fuel in the feed hopper and
throwing it upou the feed worm. This sleeve or casing is capable of being slidden
axially along the conveyer to any required extent, and by this means the initial or
receiving end of the conveyer is uncovered at any point of the variable pitch of the
worm, thereby regulating the amount of fuel taken up by the conveyer at each
revolution, and consequently the amount fed forward to the furnace. When a rotary
screw blade conveyer is employed the blades are mounted on a hollow cylinder with
their axes perpendicular to the axis of the said cylinder and capable of rotation
to a limited extent about their axes in order to vary their angle of inclination, and
This rotation is effected by
consequently the feed of the fuel to the furnace.
means of toothed racks sliding in the beforementioned hollow cylinder and gearing
with teeth or pinions on the screw blade axes, the said racks being actuated by a
sliding screw or other suitable means.
For the purpose of discharging the fuel into the furnace a specially constructed
injecting apparatus is employed. The fuel on leaving the conveyer falls or is drawn
through a channel or conduit, and is joined by one or more currents of air, and
ultimately met by a current of steam by which it is forced in a stream through a
suitably shaped nozzle into the combustion chamber of the furnace. The steam
supply is controlled by a regulating valve which is connected to the fuel feed

page_text: regulating mechanism in such a manner that, on reducing the supply of fuel the
supply of steam to the injector is proportionately reduced and vice versa.
Dated this 14th day of May 1892.
WHEATLEY & MACKENZIE,
40, Chancery Lane, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in Steam Generator and other Furnaces, and in
Apparatus for Supplying Dust or Pulverulent Fuel thereinto.
I, CHARLES CROFTON BLACK, of Hill House, Buckhurst Hill, in the County
of Essex, Salesman, 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 relates to the construction of steam generator and other furnaces
in which pulverulent fuel, such as coal dust and the like, is employed, and of
apparatus whereby the said fuel is conveyed, either automatically or by other
means, from a suitable source of supply and delivered by means of jets of air or
steam, or of both combined into the said furnace and there burned, and has for its
object to more effectually utilize the heat of combustion; to admit of readily
collecting the residual products of such combustion; to regulate the supply of fuel
according to the working requirements and to deliver it into the furnace in a
condition most favourable for its complete combustion.
:-
In the accompanying 10 sheets of illustrative drawings
Figure 1 represents a sectional elevation of one arrangement of furnace and fuel
feeding apparatus constructed according to this invention as applied to a steam
boiler and
Figures 2 and 3 are left and right side elevations respectively of the same.
Figure 4 is a cross section to an enlarged scale of steam chamber with adjustable
plate for regulating the steam jet, and Figure 5 is a sectional elevation of the same.
Figures 6 and 7 are side and front elevations to an enlarged scale of travelling
fuel feed band, and drums for carrying the same, and Figure 8 shows the method
of securing the component parts of the said band together.
The dust fuel to be burnt is fed into the hopper a through a pipe b connected to
the supply and is carried by the endless travelling feed band c passing over a
supporting plate d and from which it is removed by rotating brushes e and falls into
the chamber whence it is carried by gravity and the current of air induced by
means hereinafter described through the orifice g and into the furnace h.
The thickness of the layer of dust fuel carried forward by the feed band is
regulated by the adjustable sliding shutter or damper i, and the layer is further
regulated, and any lumps reduced by a slowly revolving rotary comb or distributor /
provided with coarsely pitched stiff wires or bristles.
The feed band, comprising a number of laths m (Figures 6, 7, 8) flexibly connected
together by links n, is stretched around drums o, p. mounted on suitable spindles
working in bearings in the frame or casing 9 as shown, the upper and driving ones o of
which are provided with stud pins engaging in corresponding holes & in the laths m.
The feed band is operated intermittently by means of a double pawlt which engages
with a ratchet wheel v mounted on the drum spindle wo, and which is connected by
an open slotted lever and connecting rod y with a crank z forming either part of
the driving pulley a a or mounted on the spindle a b, on which is also mounted the
driving pulley a a connected by the band ac to any suitable driving source.
A detent ad engaging with the ratchet wheel ae prevents any back motion of
the feed drums o. The travel of the feed band is varied within certain limits by
adjusting the free end af of the connecting rod y in the slot ag of the lever x, as
will be clearly understood from the drawing. The rotary brushes e and distributing
comb are driven from the spindle ab through suitable spur wheels a h, ai, al.

page_text: On leaving the chamber the dust fuel meets, and intermixes with, a
stream of air and steam issuing from the nozzle a m and is carried into the furnace h
in a fine state of subdivision or cloud. The air chamber or passage an is provided
with a hinged damper a o to regulate the supply of air, and is secured in any
desired position by the hinged rack ap engaging with a pin ag on the said
damper.
The steam is led from the boiler ar or other generator through pipes as into the
furnace where it is superheated or dried, and from thence to the chamber at from
which it issues through openings avand passage a wo into the nozzle a m the
passage a w being regulated by means of the adjustable regulating plate a r, all as
clearly shown.
The plate a being set, the passage of steam can be further regulated or throttled
by the valve a y in the steam pipes a s.
In order
Some portion of the fuel falling into the chamber f may not always remain in a
state of suspension or cloud, but may fall upon the inclined surface a z.
that this fuel may be kept evenly distributed the surface a z (Figures 9 and 10) is
provided with a number of parallel ribs or corrugations b b to prevent the dust
working to the sides or middle, as the case may be, when being carried down to the
opening g by the induced draught passing down the back of the brush shield b c
and through the chamber f.
In a modification shown in Figure 9 air under pressure is admitted to the
cavity bd under the brush e and is directed in a continuous stream along the
surface to prevent the lodgment of fuel.
The feed apparatus is mounted on the furnace frame be as shown.
The furnace is constructed of fire brick or other refractory material and comprises
a crown piece bf having a curved indent and arch bh and against which the
flame and inflammable gases impinge and by which they are deflected and thereby
thoroughly mixed, and a curved base bi sloping downwards towards the mouth and
provided with a bridge piece blat a short distance inwards from the arch bh.
Beneath the base bi are two air inlets 6 m, b n controlled by hinged dampers bo, bp
connected together by the rod bq and held in any position by the rack lever br
At the back of the
engaging with a corresponding pin in the damper plate bo.
bridge wall bis arranged an air flue or conduit bs which conveys the current of
air from the openings bm, bn and projects it against the crown of the flue bt.
will thus be seen that the combustible gases are first mixed and burnt in the
chamber, after which the unconsumed products of combustion pass over the
bridge band are met by and thoroughly mixed with a current of air from
the flue bs by which means the process of combustion of the fuel is completed.
It
Figure 11 represents a modified form of furnace, in which the crown bf and
arch 6 h in Figure 1 are retained, but in place of the curved base structure bi an
inclined grate is substituted. Beneath this grate is a hinged double damper or
shutter bw, by which is capable of being turned into the position indicated by
dotted lines. In the position shown the air is admitted through the grate, the air
passagen being closed, but on turning the dampers, by means of the connecting
rod by, into the position shown in dotted lines the passage through the fire grate is
closed, and the passage bn opened to the air as will be readily understood. On
starting the apparatus an ordinary fire of wood or coal is lighted on the grate bv,
the dampers being in the position shown, and the draught, passing through the
grate, while the passage b n is closed. After the furnace has acquired a sufficient
temperature to ensure ignition of the dust fuel while in suspension the positions of
the dampers are changed to those shown in dotted lines so as to divert the draught
from the grate to the passage b n at the back of the bridge b l.
In a modification of the air supply apparatus shown in section in Figure 12, the
damper and air passage b X,
bn (Figure 11) is replaced by an injector appliance
comprising an air passage bz in which a steam nozzle ca is placed. Superheated
steam is passed through the said nozzle which induces the required current of air

page_text: through the passage bz to complete the combustion of the unconsumed gases
escaping from the first combustion chamber.
In the arrangement of apparatus shown in Figures 13 to 15 inclusive, Figure 13
is a sectional elevation, Figure 14 a side elevation and Figure 15 a front elevation
of a modified fuel feed apparatus.
The feed band comprises a band cb of cotton or other fibrous or woven material
having secured to its face one or more strips of corrugated metal c c. A continuous
motion is imparted to this band by the driving pulley cd, the supply of fuel being
regulated by the speed of the said band and also by the position of a damper ce.
The brushes e (whose number may be increased if desired) are driven from the feed
band driving spindle cf through spur wheels cg, ch, ci, cl.
Steam and air under pressure are admitted through the passages cm, cn, and
converge into one continuous stream at the point co where it passes across the path b b
of the falling fuel and injects it into the furnace, and at the same time draws air
from the upper air opening cp, thus inducing a down draught which mingles with
the falling fuel. The feed of the fuel and steam is regulated to suit require-
ments by means of the worms c q, cr gearing with pinions cs, et operating
the damper ce and steam valve c through the cranks cw, cx so as to simul-
taneously open or close them as desired.
Figure 16 represents a sectional side elevation and Figure 17 a front sectional
elevation of a further modified arrangement of this invention.
Figure 18 is a longitudinal section to an enlarged scale of a part of a variable
screw blade conveyor showing regulating rack and screw blades.
'
Figures 19 and 20 are cross sections of conveyor barrel with blade operating
racks and Figure 21 is a plan of a part of the said racks.
Figure 22 is a longitudinal section of feed tube with feed blades and regulating
device, and Figure 23. is a cross section of the same.
Figures 24, 25 and 26 represent cross section and elevations respectively of
rotary perforated screening disc.
The dust fuel is fed into a hopper a in the conveyor casing or tube cy'in which
the conveyor rotates. The conveyor comprises a tube cz working in a sleeve
bearing da and driven by a pulley db mounted thereon. Inside, and fittting
loosely, the said tube slides a compound toothed rack dc whose teeth are
set in short lengths alternately at right angles to one another and facing
inwards, so that each facing pair gear with the corresponding pinion ends d d
of two rotary screw blades de formed with conical projections df bearing in
corresponding seatings in the conveyor tube cz, the two blades being capable
of independent rotary motion, but being secured together axially by means of a
projecting pin or spigot dg fitting in a socket or faucet in the other, where it
is secured by a pin pins d and groove all as clearly shown.
or
The inner end di of the rack dc works in a bearing dl, and on its reduced end d m
is loosely mounted a screw threaded sleeve dn secured in position, axially, by a screw
and washer do. The said sleeve dn is prevented from turning by a feather key in
the bracket d which slides in a groove or way in the screwed sleeve dn.
On the
screwed sleeve dn works a corresponding nut dp with screw toothed periphery
gearing with a worm dy on the spindle dr, so that as the latter is rotated in either
direction the rack is caused to slide axially through a corresponding distance
forwards or backwards in the tube cz and thereby rotate the screw blades de in a
forward or backward direction to vary the pitch of the generating screw and, with
it, the rate of feed of the fuel along the barrel or casing cy. On the inner
extremity of the tube cz is mounted a perforated screen disc ds with projecting
teeth to ensure the thorough separation of the fuel, and an even and regular flow
into the passage dt. The passage or chamber dt is supplied through the pipe dr
with air under pressure, which passes down the passage de carrying the fuel
with it in a stream and is met at the orifice dw by a stream of steam issuing from
the steam orifice dx and thereby injected into the furnace,

page_text: The sliding steam valve cv is secured to a screw dy working in a threaded worm
pinion de gearing with the worm ea on the spindle dr. Thus the rotation of the
pindle dr simultaneously, through the worm pinions dp, dz, valve cv and rack dc,
varies and regulates the supply of steam and fuel as desired.
p.
Figure 22, shows a modified arrangement for regulating the fuel feed, in which a
hand wheel eb working between brackets ec is substituted for the worm wheel d
In this case the steam valve is also operated by hand directly, and independently
of the fuel feed.
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. An apparatus for feeding dust fuel to steam generator and other furnaces
comprising an endless travelling feed band for removing the dust fuel from a hopper
having a regulating shutter or damper, a rotary regulating or distributing comb,
and clearing or taking off brushes working in a casing or chamber, a combined
steam and air injector for extracting the fuel and intermixing the said steam and
air with it and conveying the whole combustible mixture in a suspended or cloudy
condition into the furnace substantially as described.
2. In apparatus for feeding dust fuel to boiler and other furnaces: the con-
struction of an endless feed band of laths flexibly connected together by links and
stretched around rotary drums and being provided with holes engaging with pins on
the driving drum substantially as described.
3. In apparatus for feeding dust fuel to steam generator and other furnaces: the
employment of a rotary regulating or distributing comb substantially as described
and for the purpose specified.
4. In apparatus for feeding dust fuel to steam generator and other furnaces:
regulating the feed of fuel to the feed band by means of an adjustable shutter or
damper in the feed hopper substantially as described.
5. In apparatus for feeding dust fuel to steam generator and other furnaces:
operating the feed band by means of a double pawl engaging with a ratchet wheel
mounted on the driving drum or spindle and operated by a lever connected to the
driving shaft substantially as described.
2'
6. In apparatus for feeding dust fuel to steam generator and other furnaces: the
combination of the ratchet wheel double hinged spring pawl t, open adjusting link
lever and connecting rod y substantially as described and for the purpose
specified.
7. In apparatus for feeding dust fuel to steam generator and other furnaces: the
combination of the ratchet wheel r, double hinged pawl t and open adjusting link
lever with the stop ratchet and detent a e, ad substantially as described.
8. In apparatus for feeding dust fuel to steam generating and other furnaces: the
combination of the endless feed band c, rotary distributing comb and rotary
brushes e operating substantially as described and for the purpose set forth.
9. In apparatus for feeding dust fuel to steam generator and other furnaces: the
combination of the superheating steam pipes as, and steam chamber at having
openings a v, with adjustable regulating plate a substantially as described and for
the purpose set forth.
10. In apparatus for feeding dust fuel to steam generator and other furnaces: the
combination of the superheating steam pipes as, steam chamber at having
openings a v, and adjustable plate ax with the air chamber an and fuel chamber f
substantially as described and for the purpose specified.
11. In apparatus for feeding dust fuel to steam generator and other furnaces:
forming the inclined side az of chamber f with ribs or corrugations bb to prevent
the lodgment of fuel substantially as described with reference to Figures 19
and 10.
12. In apparatus for feeding dust fuel to steam generator and other furnaces:
forming a cavity bd under the brush shield bc and admitting air under pressure

page_text: thereto to blow the fuel off the surface bb and induce a downward current sub-
stantially as described with reference to Figures 9 and 10.
13. In apparatus for feeding dust fuel to steam generator and other furnaces:
the combination of the cavity bd, deflecting shield bc and corrugated surface bb
substantially as described.
14. In steam generator and other furnaces: the combination of a crown piece of
having curved indent bg, and arch bh, with a curved sloping basepiece b i having a
bridgepiece substantially as described.
15. In steam generator and other furnaces, and in apparatus for supplying dust
or pulverulent fuel thereto the combination of the crown piece bf and base bi
with the air inlets b m, bn, and air flue or conduit bs substantially as described
with reference to Figure 1 of the drawings.
16. In steam generator and other furnaces and in apparatus for supplying dust
or pulverulent fuel thereto the general arrangement and combination of parts
constructed and operating substantially as described with reference to Figures 1
to 10 inclusive of the drawings.
17. In steam generator and other furnaces: the employment, for the purpose
specified, of an inclined grate bv, bridge bl and air passage bn in combination
with a hinged double damper or shutter bw, bx substantially as described with
reference to Figure 11 of the drawings.
18. In steam generator and other furnaces as represented in Figure 11: the
combination of the crown bf with the grate bv, air passage bn and double
damper b 10, bx substantially as described and for the purpose set forth.
19. In steam generator and other furnaces: the combination of the air passage bz
with the steam nozzle c a substantially as described and for the purpose set forth.
20. In apparatus for feeding dust fuel to furnaces: the employment of an
endless feed band of fibrous or woven material faced with corrugated plate, in
combination with a feed hopper for containing the fuel to be burnt, a damper for
regulating the feed, and brushes for taking the fuel off the said band, the whole
arranged, constructed and operating substantially as described.
21. In apparatus for feeding dust fuel to furnaces, as illustrated in Figures 13
to 15 inclusive: the feed band c b, c c with corrugated face, hopper a, regulating
damper ce, taking off brushes e, and air inlet passage c p, in combination with the
steam chamber cm, air chamber c n and regulating valve cv constituting an injector
device, the whole arranged and constructed substantially as described.
22. In apparatus for feeding dust fuel to steam generator and other furnaces:
simultaneously regulating the feed of the fuel and of the steam by means of
worms gearing with pinions connected to and operating the fuel damper ce and
steam valve c r. substantially as described.
23. The arrangement and construction of apparatus for feeding dust fuel to
furnaces, combined and operating substantially as described with reference to
Figures 13 to 15 of the annexed drawings inclusive.
24. In apparatus for feeding dust fuel to steam generator and other furnaces:
the construction of a rotary fuel feed conveyor comprising a screw blade carrier
tube cz carrying adjustable screw blades de and rotating in a cylindrical feed
casing cy and having mounted on its inner extremity a rotary perforated screening
disc ds through which the fuel is forced into the fuel passage dt substantially as
described.
8
25. In apparatus for feeding dust fuel to steam generator and other furnaces:
the combination of the rack dc sliding in the tube c z and gearing with the screw
blades de, screw threaded sleeve dn mounted loosely on reduced end d m, and
threaded worm pinion dp substantially as described and for the purpose set forth.
26. In apparatus for feeding dust fuel to steam generator and other furnaces: the
combination of the rotary fuel feed device described in Claims 24 and 25 with a
combined air and fuel passage or conduit d t and steam chamber at all arranged
substantially as described.
27. In apparatus for feeding dust fuel to steam generator and other furnaces:

page_text: simultaneously regulating the feed of fuel and steam by means of the worms ea, dq
and pinions d z, d p, operating screw blades de, and steam valve cv substantially as
described.
28. In apparatus for feeding dust fuel to steam generator and other furnaces :
securing each pair of opposite screw blades together by means of a pin on one
blade fitting into a socket on the opposite one, and the two being secured together
axially by a pin or pins substantially as described and for the purpose set forth.
29. The arrangement construction and combination of apparatus for feeding dust.
fuel to steam generator and other furnaces substantially as described with reference
to Figures 16 to 26 inclusive of the drawings.
30. The arrangement and combination of parts constituting my improvements in
steam generator and other furnaces and in apparatus for supplying dust or
pulverulent fuel thereto, the whole constructed and operating substantially as
described in the foregoing Specification and illustrated in the drawings hereunto
annexed.
Dated this 14th day of March 1893.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.