Improvements in Process and Apparatus for using Pulverized Fuel and in Rotary Roasting Furnaces for Use therewith.
Year: 1898

page_text: Date of Application, 4th Feb., 1898-Accepted, 23rd Dec, 1898
COMPLETE SPECIFICATION (AMENDED).
Improvements in Process and Apparatus for using Pulverized Fuel
and in Rotary Roasting Furnaces for Use therewith.
We, EDWARD HENRY HURRY, of Bethelem, County of Northampton, State of
Pennsylvania, Engineer, and HARRY JOHN SEAMAN, of Catasauqua, County of Lehigh,
State of Pennsylvania, U.S.A., Chemist, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
The process and apparatus forming. the subject of the present invention are more
especially applicable to the manufacture of Portland cement, and may be used in
connection with an invention for which we have made application for Letters Patent
No. 2896 of even date herewith, but such process and apparatus are also applicable
for other purposes.
A practical embodiment of the improvements is illustrated in the accompanying
drawings in which Figure 1 is a sectional elevation of a roasting apparatus adapted
to the burning of pulverized fuel according to these improvements and so arranged
that it may form a part of the apparatus for the automatic and continuous process
for the manufacture of Portland cement described and illustrated in the specification
and drawings accompanying our, application for Letters Patent herein before referred
to. Figure 2 is a longitudinal sectional elevation of the improved pulverized fuel
burner or injector; Figure 3 is an end elevation of a portion of the burner; Figure 4
is a cross section of the burner on the line 5 of Figure 2; Figure 5 is a longitudinal
sectional elevation of the fuel feeder shewing a rear view of the burner and the
changeable speed driver for the primary feeder; Figure 6 is a like section of a
modified form of the primary feeder; Figure 7 is a cross section of the same;
Figure 8 is an enlarged elevation of the gearing for driving the primary feeder;
Figure 9 is a cross section of a further modification; and Figure 10 is an enlarged
section of the delivery end of the rotary roasting furnace shewing a means of cooling
the same.
Referring now to Figures 1 to 9 inclusive A is the rotary furnace which consists of
an exterior metallic shell or casing lined with fire brick and mounted in a horizontally
inclined position having tracks a which bear upon the roller bearings 6; rotary motion
being imparted to the furnace by a pinion c meshing with a toothed wheel d on the
furnace shell, the pinion being driven in any proper manner, as from a driven worm
shaft e and worm.f..
The upper or entrance end of the furnace A projects into the upper end of the
vertical chamber B forming at its lower portion an ash pit and having connection
with the stack C for the escape of the waste heat and such solid products of com-
bustion as may be carried by the draft; while the opposite or exit end of the furnace
projects into the exit chamber D having an inclined floor or chute G for leading off

page_text: the hot clinker falling from the furnace. The two chambers B and D) are formed by
masonry with fire-brick to withstand great heat. The chamber D has an opening h
closed by a door directly opposite the entrance end of the furnace to view, if need be.
the interior of the furnace and the lower portion of the clamber below the entrance
of the furnace forms the ash pit to which access may be had through a lower opening i
closed by a door; the communication of the chamber with the stack being had
through an opening preferably at the side of the chamber. This chamber D also
has a conduit m, water jacketed if need be, leading. from top of the chamber to the
entrance end of the furnace for the feed thereto of the raw material to be roasted from
any suitable source of supply.
The chamber 1) is formed with an opening 10 in line with the open end of the
rotary furnace A, which opening is continued by a cylindrical fire brick lined
chamber 12 supported by a. trolley 13 adapted to travel on the track 14 with the
chamber longitudinally away from the chamber opening 10 for access to the end
of the furnace. Normally this combustion chamber 12 will be bolted to the extreme
wall of the chamber D as shown, to prevent accidental movement and to stop the
ingress of cold air to the furnace. The outer end of the chamber 12 is closed by a
plate 15 to which the end of the burner E is secured which, when in operation, as
will be presently described, injects the powdered fuel with the small volume of high-
pressure air to form and maintain a long intense heating flame through the rotary
furnace A.
The inclined floor or chute G of this exit chamber D leads the red hot and freshly
made clinker directly into the entrance end of a conduit F consisting of a horizontally
inclined rotatable cylinda, through which the hot clinker is more or less slowly
conducted to its exit end, against a natural draft of air there-through- and which is
thereby intensely heated, to pass upward into the furnace to aid and support the
combustion of the fuel injected by the burner E. The cylindrical conduit Fis
mounted like the-furnace A to revolve on roller bearings n. and rotated by a pinion o
meshing with a toothed wheel on the cylinder, the pinion being driven in any
proper manner not necessary to describe.
The more or less open connection between the cylindrical conduit F and the exit
from the chamber D is closed against ingress of cold air by a fixed shield 16 closely
fitting the periphery of said conduit; and in like manner the connection between the
exit end of the furnace A and the chamber D is closed by a shield 17; these shields
permitting the complete utilization of the very hot air which under a natural- and
induced draft passes onward from the conduit F through the rotary furnace to support
the combustion of the fuel, injected by the burner into such furnace.
A portion of this heated air is diverted from passing directly into the chamber 1)
and is conducted by a pipe 18 connected one end to the shield 16 and the other end
detachably connected coincident with an opening in the bottom of the chamber 12, so
that a portion of the heated air needed to support the combustion of the fuel
injected by the burner meets such fuel somewhat earlier than the remainder of the
heated air to become more or less intimately mixed with the fuel before it enters the
furnace.
i
An improved form of burner E capable of practically carrying out the improved
process of injecting and burning pulverized fuel with a limited volume of high
pressure air as the injecting fluid, is shown in detail in Figures 2, 3 and 4. Said
burner consists of a fuel receiving chamber 20, a high pressure air conduit 21, leading
to said chamber, and a mixture directing tube 22 leading from said chamber, the
longitudinal axis of the tube being coincident with the axis of the air conduit. The
chamber 20 as shown is of cylindrical contour with vertical heads and having at its
upper end a spout 23 forming a portion of the vertical passage for the fuel from the
feeding device; see Figure 5. Its front wall or head has an opening 24 in which is
fitted the rear end of the directing. tube and in its rear head an opening in which is
fitted the forward end of the air conduit. The mixture directing tube 22 has its rear
end projecting a short distance into the fuel receiving chamber, the opening of said
tube slightly contracting and then gradually enlarging toward the furnace into the

page_text: full diameter of the tube. The rear portion of this tube has a flange 25 for bolting
to the front wall of the chamber 20. The front end of the tube is screw-threaded
into an enlarged conical or bell-shaped head 26 whose front end is screw-threaded
into a plate 27 secured to the end plate 15 of the chamber 12. The larger rear end
of the bell-shaped head is formed with air openings 28 surrounding the front end of
the tube 22. through which openings a limited quantity of atmospheric air is
drawn into the bell-shaped head to pass onward with the fuel injected into the
chamber 12.
The air conduit 21 consists of a tubular shell 30, terminating within the fuel
chamber in a contracted nozzle or nose piece 31 screw-threaded to the end of the
conduit and the opposite end of the conduit has a smaller central perforation 32
partially screw-threaded to receive a central spindle 33 forming a needle valve with
its forward portion having radially projecting guides and its end controlling the size,
of the orifice through the nose piece 31 and its outer end passing through a stuffing
box 35 in the outer end of the air conduit and having a handle 34 for adjusting said
valve.
The air conduit is supported by a casing 36 that is flanged at its forward end and
bolted to the rear head of the fuel chamber 20. Intermediate between said end of
the casing and the chamber is interposed the flange of an internally screw-threaded
ring or nut 37, the threads of which are engaged by the forward threaded end of the
air conduit, the outer end of the shell 30 forming said conduit passing through a
gland 39 in the casing and having grasping projections 38 to adjust the shell within
the casing with respect to said nut to vary the extent of projection of the nose piece
endi thereof within the chamber 20.
The casing 36 is formed with an annular chamber 40 in communication with the
high pressure supply pipe 41, whose end is screwed into the side of the casing, see
Figure 3, and said chamber communicated with the air conduit 21 through
openings 42 in the shell 30. In addition to the outer stuffing box or gland 39 which
is located at one side of the annular chamber 40 there is provided another packing 43
on the opposite or inner side of said chamber, the two packings being separated by a
spacing ring 44 so that both packings may be tightened by the single outer gland 39,
to prevent the escape of the high pressure air in either direction along the shell 30.
The spacing ring has lantern openings which permit free passage of the air from the
annular chamber to the air conduit 21.
In addition to the air admitted through the openings 28 to the bell-shaped
head 26, the fuel-receiving chamber is provided in its rear head or wall with a
plurality of openings 45, see Figures 2 and 4, to admit a limited quantity of atmo-
spheric air to said chamber to intimately mix with the fuel being injected forward
through the tube 22. These openings are capable of being varied in size by an
adjusting ring 46 supported on the rear head of the chamber 20 concentric with the
axis of the air conduit 21 and having openings 47 adapted to register with said
openings 45 in the chamber. The ring may be turned in any desired manner as by a
worm 48 engaging worm teeth 49 on the periphery of the ring.
The fuel feeder before referred to and shewn clearly in Figure 5 consists of a
hopper or source of supply 50, a primary feeder or conveyor 5.1 for positively feedin
a predetermined quantity of fuel from the hopper, and a secondary feeder or con-
veyor 52 for receiving the fuel from the primary feeder and delivering the fuel in an
agitated cloud to the burner E.
The hopper or bin 50, see Figure 5, may be of any desired form and capacity and
having a closed bottom. Just above the bottom is mounted the primary feeder 51
consisting in this instance of a horizontal worm mounted in suitable bearings and
rotated by a belt 3 passing around a pulley 4 fast to the shaft of the worm. The worm
passes through a passage 5 (preferably longer than shown), which extends from the
hopper to a vertical chamber 6, that communicates with the secondary conveyor 52
In the rotations of this small worm conveyor 51, a small compact body of pulverized
fuel is positively and continuously conveyed from the hopper to the chamber 6, down
which it falls by gravity into the secondary conveyor. This secondary conveyor 52

page_text: consists of a closed horizontal and longitudinally arranged chamber or tube 7 and a
longitudinal worm 8 extending the length of the chamber 7 and mounted to rotate
in suitable bearings in the end walls of the chamber with a pulley 9 fast to the worm
shaft to rotate it. The diameter of this worm 8 is say six inches, to one and one-half
inches, the diameter of the worm conveyor 51, and with a much quicker spiral than
said worm 51, and much faster rotated, so that immediately the small continuous
supply of fuel is received in the chamber 7 it is subjected to a violent tossing action
as it is carried along the chamber, with the result that when the agitated fuel arrives
at the mouth 2 of the chamber it has been tossed into a thick cloud and in such
condition descends the tube 1 and spout 23 into the fuel chamber 20 of the burner.
such descent being materially aided by the partialvacuum induced in the chamber20
by the injected high pressure air.
The agitation of this cloud of fuel discharged from the mouth of the conveyor 52
is so great that it is requisite to provide a vertical open-ended shield 53 above the
discharge end of the conveyor to prevent waste of the fuel.
The speed of the primary conveyor 51 may be varied by driving from a pair of cone
pulleys 60. while the speed of the secondary conveyor may be invariable.
In the modified form of the primary feeder shown in Figures 6 and 7 such feeder
consists of a chamber of worm conveyors 54 projecting vertically into the lower
portion of the hopper 50, each conveyor being enclosed by open-ended tubes 55 which
serve to direct a continuous compact body of fuel fromthehopper into the chamber 7
of the secondary conveyor 52. These tubes and worm-conveyor may be of different
heights so as to feed from different levels of the fuel in the hopper and thus prevent
bridging of the fuel therein. These vertical worm conveyors have their shafts
extending through the chamber 7 and are driven by bevel gears 56 from a pair of
horizontal shafts 57, two of the worm conveyors rotated by one shaft and the other
two by the other shaft. Each of the bevel gears on the shafts are adjustable thereon,
see Figure 8, to disconnect any one or more of the worm conveyors therefrom so as
to vary the quality of fuel fed to the conveyor 7, and for this purpose the gears
may be splined to the shafts and each moved thereon by a forked shifting lever 58 of
ordinary form. Each shaft will be driven by beks passing around pulleys 59 secured
to the end of the shafts.
It is, of course, apparent that the vertical forms of primary worm-conveyors maybe
combined with the horizontal form, as is indicated in Figure 9; so, too, the fuel in
the hopper may be independently stirred and kept from packing by a rotating arm or
blade 61.
With the apparatus thus constituted a continuous uniform quantity of pulverized
fuel in the form of a cloud is fed to the burner E. The high pressure air is supplied
by an air compressor H, see Figure 1, to the air conduit 21 of the burner, say at
about the pressure of twenty pounds to the square inch, the volume issuing from the
nozzle thereof being limited and may be still further lessened by the adjustment of
the valve 33. From practical use of this apparatus we have found that somewhat
less than two per cent. of the air necessary to support complete combustion of the
pulverized fuel injected is only needed to cause the fuel to be carried fully into the
roastingfurnace. The use of thislimited volume of high pressure air for the injecting
fluid causes the fuel to be injected in a long compact body, the particles of which are
held suspended in the blast comparatively close together, so that during combustion
a long concentrated intense flame is produced capable ofmost thoroughlymaintaining
the lining of the furnace at the white heat necessary to form a high grade of cement.
The fuel thus being injected into the furnace with simply enough fluid to suspend
its particles and carry the fuel onward, the vacuum induced by the force of the jet
may cause independent supplies of atmospheric air to move onward with the fuel,
such supplies being added at separate points along the travel of the injected fuel
until finally when the fuel reaches the furnace and is in the presence of the natural
draft of heated air therethrough, sufficient air will be present to support perfect
combustion. The vacuum produced in the fuel chamber by the jet of high pressure
air passing from the nozzle 31 into the tube 22 is such as to carry every particle of

page_text: fuel fed to the fuel chamber by the feeding device described into said tube so that
after long use no fuel has been found to remain in the bottom of said chamber. This
vacuum, which has been found to be equal to from 5 to 6 pounds, serves to hasten the
feed of the fuel down the feed tube 1 into the fuel chamber, prevents clogging in said
tube,and also serves to draw in such air behind the fuel as will be permitted to enter.
through the openings 45. The air, it should be understood, admitted by the
openings 45 and 28, is only a small per centage of the total amount of air needed to
support.combustion of the quantity of fuel injected by the burner into the furnace, it
being preferred to rely upon the natural current of heated air passing from the
conduit Finto the rotary furnace for sufficientair to support combustion. In addition
to the effect of this limited volume of high pressure air in forming a long intense
flame, it is apparent that in the use of the burner there is at all times insufficient air
combined with the pulverized fuel while in the burner and its adjuncts to form an
explosive mixture, so that its use is never unsafe.
The force of the injected fuel together with the natural draft through the roasting
furnaces toward the chamber B is such that we have found practically all of the solid
residue of combustion to be carried into said chamber B to either escape up the
stack Cor to fall into the ash pit, and hence no change in proportions of the cement
materials fed to the furnace has been found necessary. The carbonaceous fuel is also
injected into the roasting furnace so that the flame of combustion does not impinge
on the walls of the furnace or against the cement materials being roasted to drive
the solid residues of combustion into the material to adulterate the same.
Without the use of some cooling means adjacent the end of the furnace subjected
to the greatest heat, the exterior metallic shell of the furnace, usually of considerable
diameter and more or less expensive, quickly burns away, with the liability of the
falling-away of the unsupported fire brick lining, and thus requiring the frequent
addition of new shell portions or sections to replace the burned portions, and the
enforced idleness of the furnace during the renewing operation. In addition to the
obvious expense entailed in the work of removing or cutting away the burned-out
shell portions, and the adding of the new shell, greater expense or less and large waste
of time is had by reason of having to entirely stop the manufacture carried on by the
furnace to be repaired, to allow it to cool off sufficiently to permit its shell being
handled by the workman, as well as the time required to again get the furnace in
operation. Practice has demonstrated that by the use of the improved cooling
means now to be described the burning off of the cylinder end may be wholly
prevented.
The rotary cylindrical furnace A, see Figure 10, may be of the form shown in
Figure 1, set in a slightly inclined position and mounted to rotate and rotated in any
suitable manner.
In the present instance the exit end of the furnace is provided with an end shell .
the outer end of which is inclined slightly inwardly as shown, to prevent accidental
displacement of the fire brick lining.
The furnace end is provided with the improved cooler C, consisting of a cylindrical
jacket, of comparatively short dimension and extending with the furnace end
through the opening into the chamber D. The jacket is of sufficiently greater
diameter than the furnace shell to leave an annular space between the two for the
introduction of water thereto. The one end of the jacket is closed by an end wall k.
rigidly attached to the furnace shell, while the other end is open. The jacket, of
course partakes of the inclination of the surface, so that if a supply of water be
introduced into the open end of the jacket at its highest point at the upper side of the
furnace as by a feed pipe m, it will meet the end wall of the jacket and pass in
opposite directions around and down the outer surface of furnace shell, accumulating
more or less on the low part of the jacket below the underside of the furnace according
as the degree of inclination of the furnace may permit; the excess of water dripping
off the open end of the jacket. As the feed pipe has no connection with the furnace
or the jacket its support need not be shown.

page_text: The furnace may be additionally cooled by employing another-cylindrical jacket i¹
likewise supplied with water from a feed pipe m², which in both jackets may terminate
in two or more nozzles so that a sufficiency of water is provided for cooling
purposes.
To prevent the ingress of air past and around the jacket through the opening e,
said opening is closed byan annulus n,fittingthe exterior of thejacket and firmlybolted
to the horizontal flange of a surrounding bracket o, bolted to the wall structure D;
the surface joint between the jacket and the annulus of course permitting the free
rotation of the furnace and its jacket.
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:-
First. 1st. The herein described process of burning pulverized carbonaceous fuel in
the presence of the material being roasted, which consists in injecting the pulverized
fuel with a limited volume of high pressure air inducing a limited current of air at
atmospheric pressure with the injected fuel and supplying the air necessary to
support combustion of said fuel by a natural draft independent of the injected
mixture.
Second. 2nd. The herein described process of burning pulverized carbonaceous
fuel in the presence of the material being roasted, which consists in injecting the
pulverized fuel with a limited volume of high pressure air inducing a limited current
of air at atmospheric pressure with the injected fuel and supplying the volume
of air to support combustion by a heated natural draft independent of the injected
mixture.
Third. The-herein described method-of-burning--pulverized--earbonaceous fuel-in
the-presence-of-the-material being roasted, which consists in injecting the fuel with
a limited volume of high-pressure-air in the presence-of-a-natural draft--of-air
sufficient-to-support-combustion of said fuel and allowing-the-air-to-carry-the-solid
residue of combustion--away without impingement--against the material being
ronsted.
Fourth. 3rd. The herein described method of feeding pulverized fuel to an
injector, which consists in subjecting uniform quantities of pulverized fuel to violent
agitation to form a fuel-cloud and then presenting said fuel-cloud to the injector.
Fifth. 4th. The herein described method of feeding pulverized fuel to an injector,
which consists in subjecting the fuel toviolent agitation and simultaneously conveying
it forward in a cloud to the injector.
Sixth. 5th. The combination of a rotary roasting furnace, a stationary chamber
extendingfrom the endof the furnace,apulverized fuel injector leading to saidchamber,
a chute from the discharge end of the furnace, a rotary conduit extending from the
chute forming a natural draft from the conduit through the furnace, a shield closing
the connection between conduit and the chute, and a pipe leading from the hot air
space enclosed by the shield to the combustion chamber, as set forth.
Seventh. 6th. The combination of the rotary roasting furnace, the fixed chamber at
each end thereof, a removable chamber extending from one of said fixed chambers
and a fuel burner connected to said chamber, as set forth.
Eighth. 7th. The combination of the rotary roasting furnace, the fixed chamber at
each end thereof, a suspended chamber extending from one of said fixed chambers, an
elevated track supporting said chamber, and a fuel burner connected to said chamber
as set forth.
Ninth. Sth. The combination of the rotary roasting furnace, the fixed chamber at each
end thereof, a removable chamber extending from one of said fixed chambers, a fuel
burner connected to said removable chamber, a passage for a natural draft of air
through the furnace and a branch passage leading from said passage to the removable
chamber, as set forth.
Tenth. 9th. In a pulverized fuel burner, the combination of the fuel-receiving

page_text: chamber, an air pressure conduit terminating in a nozzle extending into said chamber,
atmospheric air orifices opening into said chamber in rear of the nozzle for an induced
current of air, and an air and fuel directing pipe leading from the chainber, as set
forth.
Eleventh. 10th. In a pulverized fuel burner, the combination of the fuel-receiving
chamber, an air pressure conduit of limited area extending into said chamber, and
atmospheric air orifices surrounding said air pressure conduit in rear thereof for an
induced current of air into the chamber, as set forth.
Twelfth 11th. In a pulverized fuel burner, the combination of the fuel-receiving
chamber, an air pressure conduit extending into said chamber, a plurality of orifices
in the chamber open to the atmosphere for an induced current of air, an air and fuel
directing pipe leading from one, chamber, and other orifices at the end of said pipe
for a further induced current of atmospheric air, as set forth.
Thirteenth. 12th. In a pulverized fuel burner, the combination of the fuel-receiving
chamber, a compound air conduit extending into said chamber and having a needle
valve for varying the volume of air admitted, a plurality of orifices to the chamber
open to the atmosphere for an induced current of air, an air and fuel directing pipe
leading from the chamber, as set forth.
Fourteenth. 13th. In a pulverized fuel burner, the combination with the high
pressure air conduit, a fuel chamber, and a directing pipe, of a plurality of orifices
leading from the chamber to the atmosphere and means for adjusting the area of the
orifices, as set forth.
Fifteenth. 14th. In a pulverized fuel burner, the combination with the high pressure
air conduit, a fuel chamber and a directing pipe, of a plurality of orifices leading from
the chamber to the atmosphere, and an adjustable ring having orifices to coincide
with the orifices of the chamber to vary their area, as set forth.
Sixteenth. 15th. In a pulverized fuel burner, the combination of the fuel chamber,
the air pressure conduit leading thereto, a chambered casing surrounding and support-
ing said conduit having communication with the air pressure supply and with said
conduit, and an air and fuel directing pipe leading from the fuel chamber, as set
forth.
Seventeenth. 16th. The combination with a pulverized fuel burner, of a pulverized
fuel feed therefor, consisting of a small primary conveyor for continuously feeding
limited compact quantities of fuel, a secondary conveyor receiving the fuel from the
primary conveyor and positively conveying it to the burner, and means for rotating
the secondary conveyor at a speed to violently agitate the fuel and deliver it in a
cloud to the burner, as set forth.
•
Eighteenth. 17th. The combination with a pulverized fuel burner of a fuel feed
therefor, consisting of a hopper having a vertical opening, a worm conveyor mounted
vertically in said opening to convey a limited compact quantity of fuel from the
hopper, a secondary conveyor to receive such fuel to positively carry it forward to the
burner and means for rotating the secondary conveyor at a speed to violently agitate
the fuel as it is carried forward, as set forth.
Nineteenth. 18th. The combination with a pulverized fuel burner, of a fuel feed
therefor, consisting of a hopper having a plurality of vertical openings, a worm con-
veyor mounted vertically in each opening to convey limited compact quantities of
fuel from the hopper, driver for said worm conveyors having means for connecting
and disconnecting one or more of the worm conveyors therefrom, and a secondary
conveyor receiving the fuel from said worm conveyors to carry it forward to the
burner, as set forth.
Twentieth. 19th. The herein described downwardly inclined and rotary furnace pro-
vided adjacent its lower and exit end with a surrounding water jacket having one
end closed and the other open, and a water feed pipe for delivering water into the
open end of the jacket.
Twenty-first. 20th. The combination with a rotary cylindrical furnace, a water
jacket surrounding its end and having one of its ends closed and the other open, and

page_text: a water feed pipe independent of and leading to the open end of the jacket, of a
chamber into which the furnace end and jacket projects, and a surrounding air-
excluding annulus fixed to the walls of the chamber, as set forth.
Dated this 3rd day of February, 1898.
E. H. HURRY.
H. J. SEAMAN.
Per. W. H. Beck,
Agent, 115, Cannon Street, London, E.C.