Year: 1887

page_text: Date of Application, 11th July, 1887
Complete Left, 11th Apr., 1888
Complete Accepted, 25th May, 1888
FREDERICK WILFRID SCOTT STOKES of 13 Holland Street Kensington London W.
Civil Engineer do hereby declare the nature of this invention to be as follows:-
In the Specification of a former Patent No. 7,888 for which application was made
by me on June 12th 1886 I described certain improvements in the manufacture of
Cement in a powered State, and in the preparation of the "Slurry" material previous
to burning.
"
The object of my present invention is to produce cement by subjecting the dried
slurry" as produced according to the first part of my invention described in my
previous specification, to intense heat of combustion in a furnace contrived so as to
keep the pieces of slurry constantly exposed to the action of the intense heat due to
the combustion of coal gas or other Hydro carbon, or coal dust, while the fragments of
slurry are themselves kept relatively in motion. Such a furnace for instance as what is
now well known as a "Revolving furnace" which being mounted on rollers and set on a
slight incline gradually, as it rotates passes the slurry from the upper end, where it is
continuously fod in, to the lower end of the Cylinder, where it comes out cement
clinker in small fragments of great uniformity and excellence of character.
In order to produce the required temperature in the Cylinder or furnace I employ
what is known "
as the regenerative system" in which the gas or air or both is heated
before ignition.
For this purpose I either use chambers containing chequered brickwork for storing
up the heat, or parallel flues alternately for the passage of the products of combustion
after leating the furnace, and air or gas.
I also sometimes prefer to use a second revolving cylinder lined with fire brick into
which the highly heated cement clinker is fed as it leaves the first furnace. The air
necessary for combustion for burning the cement passes through this cylinder,
becoming heated as it passes through it, and thus cools the clinker, while at the
same time the clinker is delivered at a convenient place for grinding.
When it is necessary that the delivery should be at a higher level, the fire brick
lining is provided with helical projections for the
purpose.

page_text: Instead of using a revolving cylinder a conveyor may be used to convey the clinker
to the stones to be ground in the usual manner when cool.
This conveyor passes along a flue arranged so that air is allowed to pass freely along
it and thus cool the cement. The air thus heated is made use of either for the purpose
of drying the slurry as described in my previous patent or for heating the air or gas
for supporting combustion; or if preferred the hot cement clinker is made to pass
along a flue through which also travels the wet slurry, so that the heat from the
cement just burnt is utilized for drying slurry.
The further object of my present invention is the formation of thin strips or sheets
of the plastic slurry for the purposes of rapid and economical drying already described
in my previous Patent, by subjecting the plastic slurry delivered from the pug mill
to pressure produced by suitable mechanism in a closed chamber provided with a
movable piston or lid and contrived with openings of the required shape & size for
forming the strips or sheets of slurry so that they may be readily dried.
Dated this the 9th day of July 1887.

page_text: сеше,
I, FREDERICK WILFRID SCOTT STOKES, of 13 Holland Street, Kensington, 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 :-
My invention relates to the manufacture and burning of cement in a continuous
manner.
My said invention comprises an improved method of producing cement by first
forming the slurry into strips, sticks or sheets of regular transverse sectional area,
then drying the same and then subjecting them to the intense heat of combustion in
a furnace so contrived as to ensure the constant exposure of the pieces or fragments
of slurry to the action of the heat by keeping the said fragments of slurry relatively
in motion such a furnace, for instance, as what is now well known as revolving
furnace," which is mounted on rollers and set on a slight incline, so that, as it rotates,
the slurry passes gradually from the upper end, where it is continuously fed in, to
the lower end of the said revolving furnace, whence it is discharged in the form of
cement-clinker in small fragments of great uniformity and excellence of character.
My said invention also comprises various other improvements hereinafter set
forth.
In order to produce the required temperature in the aforesaid revolving furnace, I
prefer to employ what is known as the "regenerative system," that is to say, the gas
or air or both are heated, before ignition, by the waste products of combustion.
For this purpose either employ chambers containing chequered brickwork and
provided with valves so that they can be used alternately for storing up the heat and
for giving up the same to the air or gas, or I employ parallel or cross flues or tubes
for the passage of the products of combustion after leaving the furnace.
In the accompanying drawings, I have shown how my said invention may be con-
veniently and advantageously carried into practice.
Figure 1 is a vertical longitudinal central section of one form of my improved
apparatus.
Figure 2 is a plan of the said apparatus, a portion of the top being removed.
Figure 3 is a transverse section on the line a, a, Figure 1, and
Figure 4 is a transverse section on the line y, y, Figure 1, the revolving cylinder
or furnace being removed.
Figure 5 is a vertical longitudinal central section, and
Figure 6 a transverse section on the line, , Figure 5, showing a modification of
my said invention.

page_text: Figure 7 is a vertical longitudinal central section, showing a further modification
of my said invention.
Like letters indicate corresponding parts throughout the drawings.
A is the revolving cylinder or furnace, B is a gas-producer, is the regenerator
hereinafter described, D is the hopper for feeding in the slurry, E is the delivery
aperture for the cement.
The revolving cylinder or furnace A is provided with a fire-brick lining a having
projections a¹, and lips or flanges a² for retaining the slurry in the said cylinderr or
furnace. The said furnace is mounted on rollers carried in flanges or rings ₁
around the periphery of the said cylinder or furnace A, and forming what is usually
termed a live-ring of rollers, the said rollers & bear against rails or bearing surfaces.
The cylinder or furnace A is so arranged as to incline slightly from the hopper D,
through which the slurry is fed into the same, down-to the cement-delivery aperture E,
and is provided with air-tight joints at a³. The said cylinder or furnace A is, more-
over, provided with means for applying power to rotate the same, comprising a
worm-wheel or ring with which gears a worm d fixed on a shaft d' carried in suitable
bearings. This shaft has at one extremity a fast pulley e and a loose pulley el for
connection with a suitable motor. A thrust-roller is mounted upon a bracket and
adapted to bear against a plate or flange g on the cylinder or furnace and thus obviate
any tendency which the said cylinder or furnace would otherwise have to slip in the
direction in which it is inclined.
placed
above
The cylinder or furnace A is surmounted by a brick arch supported upon girders h¹
which are carried upon columns h or otherwise. The air heated by radiation from
the exterior of the said cylinder or furnace is intercepted by means of hoods
at each side of the latter, which form in conjunction with the arch ha space
the cylinder or furnace A, in which the heated air is collected and conveyed to the
regenerator Chereinafter described, which it enters through the aperture j.
The gases necessary for combustion for the purpose of burning the cement in the
revolving cylinder or furnace A, are produced by means of the gas-producer B,
which is fed with coal or other fuel through a hopper & having a sliding top or cover k¹,
and a second slide ², beneath which is a worm or screw-conveyor having a
pulley for driving the same. By means of the worm or conveyor 1, the coal or
other fuel is fed continuously in small quantities to the chamber beneath, thus
producing a continuous and regular supply of gas to the cylinder or furnace A. The
gas produced in the said gas-producer B passes into the cylinder or furnace A through
the passage m, and, mingles with the hot air delivered through the passage n from the
regenerator C hereinafter described; the combustion of this mixture of gas and air
takes place in the revolving cylinder or furnace, the lower part or portion of which
forms a combustion chamber. The products of combustion pass through the interior
of the cylinder or furnace A, burning the cement contained in the same, and pass
thence to the regenerator C, through which they slowly travel and whence they are
carried away by means of a suitable Hue to the chimney-shaft; or the said products
of combustion may be employed as herein described for drying the slurry.
The regenerator C is a passage or chamber extending the entire length of the
cylinder or furnace A and situated over the same. It has vertical cross tubes o, o',
03, 03, preferably made of fire-brick or other refractory material, and air-passages p, p'
below and above it. The hot air rising from the exterior of the cylinder or furnace A
is caught by the hoods and passing along the space is carried to the aperture j,
through which it passes into the regenerator C. As the said heated air is prevented from
passing through the passage p by the check q, it rises through the vertical cross tubes
and passes along the upper passage p', until stopped by the check g', when it descends
through the tubes o' to the lower passage p, along which it travels until it meets the
check 2, which forces it again to rise through the tubes o² to the upper passage p',
along which it again travels, finally descending through the tubes o³ to the lower
passage. The lower
passage and the upper passage are sometimes divided
longitudinally by partitions,³; the heated air in the regenerator C is thus.divided
V₁

page_text: into two currents, one of which is delivered by the passage n to the combustion-
chamber in the cylinder or furnace, and the other by the passage to the lower part
of the gas-producer B.
By causing the current of air to pass thus from the lower passage p to the upper
passage and rice versa through the tubes o, 01, 02, 0³, the said current of air is
thoroughly heated before being delivered respectively to the said combustion chamber
and gas-producer. The air necessary for combustion is drawn or sucked into the
regenerator through the aperture; in case, however, enough air cannot be obtained
by means of the current induced by the draught from the chimney, I provide pipes or
tubes s having stop-cocks s¹ and communicating with an air-compressor, blower or
other means for producing a jet or jets of air in the passages n, r'. I sometimes
introduce the said air under pressure through the aperture j.
The slurry is delivered by means of the elevator into the hopper D, by which it is
fed into the upper end of the cylinder or furnace A. The said hopper D is provided
at its lower extremity with a shaking or vibrating feed 1. The slurry passes from the
hopper D to the cylinder or furnace A through the passage w, the upper part of which
is fitted with a door or flap u so arranged that it opens automatically when a certain
weight of slurry presses against it from behind, and closes when the same has passed
into the revolving cylinder or furnace A.
I provide, moreover, suitable doors and sight-holes v', and also a conveyor or
series of trucks w for removing the hot cement.
The conveyor w passes along a flue el so arranged that either the products of com-
bustion or atmospheric air are allowed to pass freely along it and thus to some extent
cool the cement. The products of combustion or the air thus heated are made use of
either for the purpose of drying the slurry or for heating the air or gas for supporting
combustion or if preferred the hot cerent-clinker is made to pass along a flue
through which also travels the wet slurry; so that the heat abstracted from the cement
just burnt is utilized for drying the slurry.
Figures 5 and 6 show a modification of my said invention in which the regenerator C
is formed separately from the revolving cylinder or furnace A and is placed at one
side of the same; in this case the vertical cross tubes are dispensed with, and hori-
zontal partitions are provided forming passages a¹ for the products of combustion
and passages for the air to be heated by the same.
Figure 7 shows a further modification of my invention wherein I employ a
device for producing gas or vapour from mineral or other hydrocarbon oils for com-
bustion in the cylinder or furnace A. For this purpose I provide a convenient
chamber or receptacle y to hold the oil to be vapourized. This chamber or
receptacle y is fed with oil by means of the pipe or tube which is provided with a
suitable stop-cock 2, and communicates with a convenient tank or reservoir or other
supply of oil.
I sometimes prefer to use, instead of the conveyor w, a second revolving cylinder
or chamber lined with firebrick, into which the highly heated cement-clinker is fed as
it leaves the revolving cylinder or furnace A, and through which air may be passed
for the purpose of heating the same' by heat abstracted from the said clinker, which is
thus more or less cooled. When it is required to convey the cement-clinker to a
higher level, this revolving cylinder or chamber is provided with helical,
grooves
for feeding or carrying along the said cement-clinker. The products.of combustion,
after leaving the regenerator, are sometimes caused to pass through this cylinder,
so that they will be relicated and thus at the same time cool the clinker. The
clinker is, moreover, delivered at a convenient place for grinding. The reheated
products of combustion are then employed for drying the slurry.
I sometimes form the thin strips, sticks or sheets of slurry, by subjecting the plastic
slurry delivered from the pug-mill, to pressure in a cylinder or chamber which is
closed with the exception of numerous holes through which the plastic slurry is forced
by a movable piston or lid, thus forming strips, sticks or sheets of slurry of regular
or uniform,transverse, sectional area, so that they may be readily and uniformly dried

page_text: and burnt. Or I form the said sticks, strips or sheets of slurry in the manner
described in the specification of former Letters Patent granted to me and dated
12th June A.D. 1886 No. 7888.
It is obvious, moreover, that my improved apparatus may be further modified
if desired for instance, the rollers can be placed in brackets upon girders or
other suitable supports, and the revolving cylinder or furnace be provided with
rings to hear against the said rollers. The regenerator may be placed underneath
the revolving cylinder or furnace. The said revolving furnace may be made of
any suitable form in transverse section. The slurry may be fed into the revolving
cylinder or furnace through a pipe. Twin gas-producers, or single gas-producers
of any suitable description may be employed in combination with the said revolving
cylinder or furnace.
By the above described improved process of burning cement in strips, sticks, or
sheets of regular or uniform sectional area I secure great uniformity of burning,
and produce cement of a superior quality. I obviate, moreover, the defects arising
when lumps or pieces of cement of varying dimensions are employed some of the
larger lumps passing through the revolving furnace partially unburnt, and thus
spoiling the quality of the cement when ground. Moreover the cement, in my
process, is not carried away into the flues as is the case when it is burnt in the
form of powder. My improved process, moreover, greatly reduces the power
required for grinding.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I wish it under-
stood that I do not claim broadly or apart from my improvements herein described
the manufacture of cement by heating the slurry in a revolving furnace whereby it
is agitated or kept in motion, as I am aware that slurry has been thus treated while
in the form of powder or very small particles, and also that it has been proposed to
so treat slurry in the form of lumps of various sizes which would necessarily be
unequally burnt. The burning of the slurry while in the form of strips, sticks or
sheets of regular or uniform transverse sectional area, is, however, an important
feature of my present invention as I am thus enabled to effect the previous drying of
the slurry in a very rapid and economical manner and also to ensure the uniform
heating or burning of the same in the cylinder or furnace as above specified; and I
claim
First. The improved method or process of producing cement by first forming the
slurry into strips, sticks or sheets of regular or uniform transverse sectional area, then
drying the same and then subjecting them to intense heat in a revolving cylinder or
furnace, while they are kept relatively in motion, substantially as, and for the purpose,
set forth.
Second. The above described method or manner of simultaneously abstracting
some of the heat from the burnt cement and heating the waste products of com-
bustion or atmospheric air to be used for drying the slurry or for other purposes, as
herein set forth.
Third. The employment of a conveyor lined with fire-brick or other refractory
material and arranged to pass along a flue through which the waste products of
combustion or the wet slurry are caused to pass, substantially as, and for the
purposes, set forth.
Fourth. The conveyor consisting of a revolving cylinder lined with fire-brick or
other refractory material (with or without the helical grooves) and so arranged that
the waste products of combustion or atmospheric air will pass through the same,
substantially as, and for the purposes, set forth.
Fifth. In my improved apparatus for burning cement, the provision for utilizing
compressed air for inducing currents of air into the regenerative chamber, substan-
tially as, and for the purpose, above specified.
Sixth. The combination of a regenerative chamber, a revolving cylinder or furnace

page_text: and a hood or casing for collecting the heat radiated from the said cylinder or
furnace, substantially as described.
Seventh. The combination of an elevator, hopper and continuous feed with a
revolving cylinder or furnace, substantially as, and for the purposes, set forth.
Eighth. The improved method of forming the slurry into strips, sticks, or sheets
by forcing it in a plastic state through suitable apertures in an otherwise closed
cylinder or chamber by means of a piston, substantially as, and for the purpose, set
forth.
Ninth. The improved apparatus consisting of the parts constructed and combined
substantially as described with reference to Figures 1 to 4, or with reference to
Figures 5 and 6 or Figure 7 of the accompanying drawings, and operating as, and
for the purposes, specified.
Dated this 10th day of March 1888.
WILFRID STOKES.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.