Improvements in Revolving Furnaces for Burning, Calcining, or Roasting Cement, Lime, Ores, or similar Substances.
Year: 1888

page_text: Date of Application, 13th Nov., 1888
Complete Specification Left, 12th Aug., 1889-Accepted, 14th Sept., 1889
PROVISIONAL SPECIFICATION.
Improvements in Revolving Furnaces for Burning, Calcining, or
Roasting Cement, Lime, Ores, or similar Substances.
I, FREDERICK WILFRID SCOTT STOKES of 13 Hollond Street Kensington London W.,
Civil Engineer do hereby declare the nature of this invention to be as follows:-
In my previous Specifications Nos. 9694/87 & 9986/88 I described certain improved
apparatus for burning cement in a revolving furnace, and for the subsequent cooling
of the same by means of currents of air in a second revolving cylinder or conveyor.
The object of my present invention is to combine the burning & cooling operations
in one cylinder.
For this purpose I use a long cylinder made of cast or wrought iron or steel, set on
an incline.
The cylinder is lined with a highly refractory material such as the best fire brick or
ganister, and is mounted on a series of three or more fixed or "free" rollers, the
seatings for which are adjustable and provided with springs arranged to carry the
proper proportion of the weight of the cylinder.
Thrust rollers are provided to maintain the cylinder in position.
The upper end of the cylinder is in connection directly with the chimney with a
drying cylinder Specn. 9986/88, with drying table Specn. 10,764/87, or with drying
floors, or other arrangements for using the waste heat.
A feed incline or feed spout is contrived in the brickwork at the upper end through
which the cement materials, ore &c. in the form of powder, granules or small pieces
are introduced, either direct from the drying apparatus, or from a mechanical shaking
or other feed for delivery at a uniform rate.
The upper part of the cylinder is for heating & burning the material, the lower part
for cooling the burnt material & heating the incoming air & fuel.
For this purpose the lower portion of the cylinder is provided with an internal pipe
supported either at intervals or by continuous straight or spiral partitions terminating
about midway in the length of the cylinder. This pipe supplies the gaseous or liquid
fuel for the furnace. The roasted or burnt material passes along the chambers thus
formed between the pipe & cylinder & parting with its hent to the walls thus effectually
heating the air & gas or converting the liquid fuel into gas before reaching the point
of ignition. The upper end of the fuel pipe is arranged with suitable openings for
ensuring complete combustion of the gasses. The lower end of the pipe is provided
with a sliding moveable joint made tight by means of a gland & asbestos or other
packing.
Gas is obtained from a gas producer arranged to maintain the heat of the gas as
much as possible.
When liquid fuel is used the moveable joint is connected to a supply pipe fed either
by gravitation or by means of a small pump.
The burnt material falls from the lower end of the cylinder cool enough to be readily
handled, and removed by a conveyor, trucks, or otherwise.
The revolving furnace may be either truly cylindrical or formed of a combination
of truncated cones, and cylinders or it may be polligonal in cross section.
I sometimes prefer to form the lower or cooling part of the cylinder of three or
more smaller cylinders grouped round the centre fuel pipe.. Each cylinder is complete
in itself, but is secured to the rest and the whole mounted with roller paths running
on rollers.
In this case the fuel pipe projects into the burning part of the cylinder, and the
burnt material finds its way into the unner ends of the cooling cylinder.

page_text: I sometimes prefer to make this cooling group of cylinders distinct from the
burning cylinder, and revolving at a different speed.
The driving gear for the cylinder is either one or more worms & worm wheels fixed
to the cylinder, or driving the axles of the supporting rollers.
I also sometimes use ordinary toothed gearing, or chain gearing carried on arms
projecting from the cylinder.
In cases where no internal fuel pipe is provided in the lower part of the cylinder, I
arrange ports or openings in the skin & lining of the cylinder for the admission of the
gas or liquid fuel.
A hood & casing with gas tight joints, covers the cylinder at this point, and is
connected by a pipe with the supply. The ports may be made to close automatically
to prevent the burnt material falling into them, by means of a series of lumps mounted
on a band contrived so that the lumps fit the openings in the lower positions, but rise
clear in the upper. Perforated bricks may also be used for admitting the gas.
In order to control the passage of the material through the cylinder, the lining is
sometimes made of unequal thickness, forming a gentle spiral with sloping sides where
the heat is great.
The pitch of the spiral may be different in the upper & lower portions of the
cylinder.
The lining bricks of the cylinder are uneven on the inner face, and are sometimes 1
formed with air channels, through which air may be drawn & heated for the gas
producer, or for other purposes.
Another way of combining the burning & cooling operations in one cylinder is as
follows:-
A metal cylinder or truncated cone is mounted & driven as previously described.
An internal cylinder or truncated cone is formed of segments of fire brick or other
refractory material. The walls of this internal cylinder are supported by spiral
partitions extending to the skin of the outer cylinder. The lower end of the internal
cylinder stops short of the outer one, which is closed except for the, admission of
gaseous or liquid fuel. The upper end of the internal cylinder projects somewhat and
is conneeted with the chimney flue, and with an inclined feed through which the
material to be burnt enters.
The material enters the upper end of this cylinder, travels along it, and falls from
the end into the space left between it & the outer cylinder. It is then fully burnt, &
as the furnace revolves passes back along the spiral chambers formed by the lining.
On reaching the upper end of the cylinder it is cool & falls out onto a conveyor. The
air for combustion enters the spiral chambers & travels to the point of combustion,
becoming heated on it way.
The cylinders may be grouped in couples "Head and Tail" or side by side as most
convenient for feeding and collecting the materials.
Dated this 12th day of November 1888.
7
COMPLETE SPECIFICATION.
Improvements in Revolving Furnaces for Burning, Calcining, or
Roasting Cement, Lime, Ores, or similar Substances.
I FREDERIOK WILFRID SCOTT STOKES of 13 Holland Street Kensington London, W.
in the county of Middlesex 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 :-
In my previous specification No. 9694/87 & 9986/88 I described certain improved
apparatus for burning Cement in a revolving furnace, and for the subsequent cooling
of the same by means of currents of air in a second revolving cylinder or conveyor..
The object of my present invention is to combine the burning & cooling operations

page_text: in one cylinder, by arranging the point of combustion nearly mid way in the length of
the apparatus, so that the upper end is utilized as the furnace, while the lower portion
acts as the cooling and regenerative chamber, otherwise the operations are similar to
those described in the above mentioned specifications 9694/87 & 9986/88, relating to
burning and cooling drums.
For this purpose I use a long cylinder made of cast or wrought iron, or steel, set on
an incline.
The cylinder is lined with a highly refractory material such as the best fire brick,
organister, and is mounted on a series of three or more fixed or "free" rollers, the
seatings for which are adjustable, and provided with springs arranged to carry the
proper proportion of the weight of the cylinder.
Thrust rollers are provided to maintain the cylinder in position.
The upper end of the cylinder is in connection directly with the chimney, with a
drying cylinder Speen. 9986/88, with a drying table Specn. 10764/87, or with drying
floors, or other arrangements for using the waste heat.
A feed inclino, or feed spout, is contrived in the brickwork, at the upper end,
through which the cement materials, ore ele. in the form of powder, granules or small
pieces are introduced, either direct from the drying apparatus, or from a mechanical
shaking, or other feed for delivery at a uniform rate.
The upper part of the cylinder is for heating & burning the materials, the lower
part for cooling the burnt material & heating the incoming air & fuel.
For this purpose the lower portion of the cylinder is provided with an internal pipe,
supported either at intervals, or by continuous straight or spiral partitions, terminating
about midway in the length of the cylinder. This pipe supplies the gaseous or liquid
fuel for the furnace.
The roasted or burnt material passes along the chambers thus formed between the
pipe & cylinder, and parting with its heat to the walls effectually heats the air &
gas or converts the liquid fuel into gas before reaching the point of ignition.
The upper end of the fuel pipe is arranged with suitable openings for ensuring
complete combustion of the gases. The lower end of the pipe is provided with a
sliding movable joint made tight by means of a gland, and asbestos or other
packing.
Gas is obtained from a gas producer arranged to maintain the heat of the gas as
much as possible.
When liquid fuel is used the movable joint, is connected to a supply pipe, fed either
by gravitation, or by means of a small pump.
The burnt material falls from the lower end of the cylinder cool enough to be readily
handled, and removed by a conveyor, trucks or otherwise.
The revolving furnace may be either truly cylindrical, or formed of a combination
of truncated cones, and cylinders, or it may be polygonal in cross section.
I sometimes prefer to form the lower or cooling part of the cylinder of three, or more
smaller cylinders grouped round the centre fuel pipe. Each cylinder is complete in
itself, but is secured to the rest, & the whole mounted with roller paths running on
rollers.
In this case the fuel pipe projects into the burning part of the cylinder, and the
burnt material finds its way into the upper ends of the cooling cylinders.
I sometimes prefer to make this coofing group of cylinders distinct from the burning
cylinder, and revolving at a different speed.
The driving gear for the cylinder is either one or more worms, & worm wheels fixed
to the cylinder, or driving the axles of the supporting rollers. I also sometimes use
ordinary toothed gearing, or chain gearing, carried on arms projecting from the
cylinder.
In cases where no internal fuel pipe is provided in the lower part of the cylinder,
I arrange ports, or openings in the skin & lining of the cylinder for the admission
of the gas or liquid fuel.
A hood & casing with gas tight joints, covers the cylinder at this point, and is
connected by a pipe with the supply. The ports may be made to close automatically

page_text: to prevent the burnt material falling into them, by means of a series of lumps
mounted on a band contrived so that the lumps fit the opening in the lower
positions, but rise clear in the upper. Perforated bricks may also be used for
admitting the gas.
In order to control the passage of the material through the cylinder, the lining
is sometimes made of unequal thickness, forming a gentle spiral with sloping sides
where the heat is great.
The pitch of the spiral may be different in the upper & lower portions of the
cylinder.
The lining bricks of the cylinder are uneven on the inner face, & are sometimes
formed with air channels, through which air may be drawn & heated for the gas
producer, or for other purposes.
Another way of combining the burning & cooling operations in one cylinder, is
as follows:
=
A metal cylinder or truncated cone is mounted & driven as previously described. An
internal cylinder or truncated cone is formed of segments of fire brick, or other
refractory material.
The walls of this internal cylinder are supported by spiral partitions extending to
the skin of the outer cylinder. The lower end of the internal cylinder stops short of
the outer one, which is closed except for the admission of gaseous or liquid fuel.
The upper end of the internal cylinder projects somewhat and is connected with the
chimney Alue, and with an inclined feed through which the material to be burnt is
admitted.
The material enters the upper end of this cylinder, travels along it, and falls from
the end into the space left between it & the outer cylinder. It is then fully burnt,
& as the furnace revolves passes back along the spiral chambers formed by the lining.
On reaching the upper end of the cylinder it is comparatively coul & falls out on to
a conveyor or trucks.
The air for combustion enters the spiral chambers, & travels to the point of
combustion, becoming heated on its way.
The cylinders may be grouped in couples "Head & Tail" or side by side, as most
convenient for feeding & collecting the materials.
In the accompanying drawing I have shewn how my said invention may be
conveniently and advantageously carried into practice.
Fig. 1. is a vertical longitudinal central section of one form of my improved
apparatus.
Fig. 2. is a plan of the said apparatus.
Fig. 3. is a cross sectional view taken just below the point of combustion.
Fig. 4 is a longitudinal vertical part section of the apparatus arranged with the
cooling portion formed of four tubes and a central gas tube.
Fig. 5 is a cross sectional view takon through the cooling tubos.
Fig. 6 is a cross sectional view of the cooling portion arranged with three tubes
and a central liquid fuel pipe.
Fig. 7 is a longitudinal vortical central section shewing another form of the
apparatus in which the cooling operation takes place in spiral passages arranged
around the furnace.
Fig. 8 is a plan of the same.
Fig. 9 is a cross section of the same.
Like letters & figures indicate corresponding parts throughout the drawings.
Figs. 1, 2 & 3 shew one form of the apparatus. A, B is a long revolving cylinder
or drum, made of cast or wrought iron, or steel set on an incline and mounted
on bearing rollers 2, 3 & 4 so as to revolve freely. The upper portion B is the
burning chamber, & the lower portion A is the cooling chamber.
The cylinder is lined with a highly refractory material 1 such as firebrick or
ganister with spaces or cavities filled with silicate cotton or the like. The cylinder
is mounted on "free rollers" and carriages 2, 3, 4 of which 2 is mounted on fixed
pedestals, while 3 & 4 are provided with rollers allowing of longitudinal movement

page_text: of the cylinders. 3 is also provided with adjustable springs 5, fig. 3, arranged so
as to take the due proportion of the weight of the cylinder at all times.
A turning worm, & wheel 6, and thrust ring, & roller 7, 7¹ are also provided.
The upper end of the cylinder is built into the brickwork 8, forming the exit for
the burnt gases, and the inlet 9 for the materials to be burnt. Sufficient play is
left between the cylinder & the brickwork to allow for the increase in length
when the furnace is heated.
The lower portion of the cylinder A is provided with a gas tube 10 made of
refractory material, terminating at 11 with a length formed of plumbago, silica
asbestos or the like.
The gas tube is supported by radial projections 12, extending from the lining
inwards.
The lower end of the tube is provided with a fixed gland 13, arranged at the
end of the bent pipe 131 which dips into an anular joint 133, filled with tar or
the like, so as to form a gas tight joint with a certain freedom of movement, to
allow of inequalities in the adjustment of the tube in the centre of the cylinder.
Gas is admitted from the main 14, through the valve 15, from a gas producer
of convenient construction.
A movable gas ring 16, is provided for heating up the walls of the cooling
cylinder when starting.
The projections 12, are either occasional or continuous, & parallel with the axis,
or spiral forming shelves on which the material to be cooled is turned over & over.
The tube is formed in lengths, with socket joints arranged for the necessary
expansion & contraction.
Asliding damper 17, is arranged on the gas pipe for controlling the admission
of ar to the furnace.
A truck, or conveyor 17' receives the burnt material.
Figs. 4 & 5 shew another form of combined furnace & cooler in which the cooling
portion is formed of a number of smaller cylinders, or tubes 18, grouped round the
centre gas tube 19.
The gas tube is shown connected directly with the gas producer G, by means of
a gland 191, mounted on a sliding plate 192, carried on the face of the gas producer G ;
a sliding damper 17, & a conveyor 17¹, for removing the burnt material are also
provided.
A roller path 20, is arranged for supporting the cooling tubes, also other mountings,
turning gear etc. as in figs. 1, 2 & 3.
The burnt material enters the tubes & in its passage through them gets cooled
by the air for supplying the furnace.
Fig. 6 shews a cross section of a series of cooling tubes 21, arranged round a
pipe 22, supplying liquid fuel.
When a spray burner is used a steam pipe is also led along the centre, up to
the point of combustion, being arranged at the lower end with glands allowing of
the free movement of the joints.
Another form of apparatus is shewn in figs. 7, 8 & 9.
In this case B is the burning chamber, formed of fire brick segments 23, supported
on spiral partition walls 24, reaching to the outer lining 25, which is contained in the
metal cylinder or drum 26. The spaces between the spiral partition 24, form passages
for the supply of the air for combustion, & also for conveying the burnt material
to the conveyor, or truck 27, as the cylinder revolves.
The cylinder is mounted on free rollers 2 & 4 & with turning gear 6, & thrust
roller 7, as previously described.
The brickwork 8 forms the inlet for the materials to be burnt, and the egress for
the burnt gases. The gas producer G has a projecting gas tube 28, entering the
lower end of the cylinder where the ignition of the gas takes place.
A valve 29 regulates the supply of the gas.
Various man holes, sight holes, etc. 30 are provided for examination & access.

page_text: In the foregoing description, & in the accompanying drawings I have set forth
several ways in which my invention may be carried into practice with advantage, but
I wish it to be distinctly understood that I do not confine myself to the precise
arrangements shown or described, or the combination of the various modifications in
relation to the other parts of the apparatus shewn.
It is obvious that without departing from the nature of my said invention the
various parts may sometimes, with advantage be further modified.
For instance :-
The mounting of the cylinders may be on rollers revolving on axles carried by
fixed, or rocking carriages.
The provision for expansion may be by means of rocking supports in place of
rollers.
Portions of the cylinders may be utilized as a drying drum.
The requisite temperature may be produced by the combustion of Water gas,
crude creosote, or other cheap Hydro-carbon, either in the form of spray or otherwise,
in any of the well known methods; or by means of powdered fuel fed in with the
air necessary for combustion.
The burning chamber may be enlarged at its upper end, so as to hold a larger
quantity of the unburnt materials, or the upper portion of the furnace may be
provided with shelves reaching to the axis of the drum, and arranged so as to pick
up as much heat as possible, and impart it to the material thereon.
The cooling tubes may be polygonal, or rectangular, in cross section, & of larger
area at the end nearer the burning chamber.
Having now particularly described & 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 :-
1st. The improved apparatus consisting of a combined revolving furnaco, and
cooling chamber contained in a metal cylinder or drum substantially as, & for the
purposes set forth.
2nd. The modification of the aforesaid apparatus consisting of a revolving furnace
in connection with a series of cooling tubes or chambers, & a fuel pipe revolving
with it substantially as, & for the purposes set forth.
3rd. The improved apparatus consisting of a revolving furnace formed of refractory
material supported by spiral partitions and forming regenerative passages contained in
a metal cylinder or druin substantially as, & for the purposes described.
Dated this 12th day of Anơust 1889.
FREDERICK WILFRID SCOTT STOKES.
FREDERICK WILFRID SCOTT STOKES.