IMPROVEMENTS IN CALCINING KILNS
Year: 1874

page_text: LETTERS PATENT to Charles William Siemens, of No. 12, Queen
Anne's Gate, Westminster, in the County of Middlesex, and Andrew
Stein, of Betchworth, in the County of Surrey, for the Invention of
“IMPROVEMENTS IN CALCINING KILNS."
PROVISIONAL SPECIFICATION left by the said Charles William Siemens
and Andrew Stein at the Office of the Commissioners of Patents,
with their Petition, on the 9th October 1874.
We, CHARLES WILLIAM SIEMENS, of No. 12, Queen Anne's Gate,
Westminster, in the County of Middlesex, and ANDREW STEIN, of
Betchworth, in the County of Surrey, both do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN CALCINING KILNS," to be as
follows:-
:-
Our Invention relates to kilns for calcining lime, cement, plaster, ores,
or other analogous materials by the combustion of gaseous fuel, and
consists in improvements in the construction and working of such kilns,

page_text: one form of which was described in the Specification of a Patent granted
to the said C. W. Siemens on the 21st August 1867, No. 2395.
According to our present improvements the kiln is made conical
throughout its height tapering to a larger diameter at the bottom, so
that the materials fed into it at the top can freely descend by gravity as t
portions are withdrawn from below. The taper of the upper part is
however very slight until at or about the level of the apex of an
internal cone or pyramid which will be hereafter described, below
which level the expansion is made much more rapid, in such manner
that as the descending mass of material is penetrated and broken up by :
the cone or pyramid the increasing annular space round the cone or
pyramid affords room for the expansion and spreading out of the
material so broken up. The top of the kiln may be domed over or
otherwise covered leaving a contracted opening for feeding, and this
opening is provided with a slide or damper whereby the draught through :
the kiln can be regulated. Sight holes are also provided at different
heights through which the character of the heat and the draught can be
observed.
The internal cone or pyramid is made of metal or other refractory
material, or its lower part may be of metal with an apex of fire-clay.
Through the sloping sides of the cone or pyramid separate passages are
formed for the air and combustible gas, these passages being so arranged
that each current of gas has on each side of it a current of air. The gas
passages radiate from a chamber in the middle of the cone or pyramid,
which chamber is supplied by a pipe or flue from an ordinary gas
producer, or it may be with the waste gases from a blast furnace. The
air passages open from a chamber surrounding the gas chamber, air
entering the said chamber by an aperture controlled by a valve or
damper. A door is provided in the gas chamber by which access can be
obtained for clearing out the gas passages without stopping the working
of the kiln. The cone or pyramid is kept comparatively cool by the
passage of the air and gas through it, their mixture and combustion not
taking place till after they have issued into the body of the kiln.
For discharging the calcined materials a number of openings are
provided at the bottom of the annular space surrounding the internal
cone or pyramid. These openings are provided with sliding doors or
flaps at some distance, above which are sliding bars supporting the

page_text: contents of the kiln. The door or flap being closed the bars above it are
withdrawn, whereupon a portion of the calcined material drops on the
door or flap, and the bars being replaced and the door or flap opened
this portion is withdrawn.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles William Siemens and Andrew Stein in the
Great Seal Patent Office on the 9th April 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, CHARLES
WILLIAM SIEMENS, of No. 12, Queen Anne's Gate, Westminster, in the
County of Middlesex, and ANDREW STEIN, of Betchworth, in the County
of Surrey, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Ninth day of October, in the year
of our Lord One thousand eight hundred and seventy-four, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs, and successors,
give and grant unto us, the said Oharles William Siemens and Androw
Stein, Her special license that we, the said Charles William Siemens
and Andrew Stein, our executors, administrators, and assigns, or such
others as we, the said Charles William Siemens and Andrew Stein,
our executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN CALCINING KILNS," upon the condition (amongst others)
that we, the said Oharles William Siemens and Andrew Stein, our
executors or administrators, by an instrument in writing under our or
their hands and seals, or under the hand and seal of one of us or them,
should particularly describe and ascertain the nature of the said Inven-
tion, and in what manner the same was to be performed, and cause
the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that we, the said Charles William Siemens and
Andrew Stein, do hereby declare the nature of the said Invention, and

page_text: in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement thereof, reference
being had to the accompanying Sheet of Drawings, and to the figures
and letters marked thereon, that is to say :-
Our Invention relates to kilns for calcining lime, cement, plaster,
ores, or other analogous materials by the combustion of gaseous fuel,
and consists in improvements in the construction and working of such
kilns, one form of which was described in the Specification of a Patent
granted to the said C. W. Siemens, on the 21st August 1867, No. 2395.
We will describe our present improvements referring to the accom-
panying Sheet of Drawings, of which Fig. 1 represents a vertical section
of the improved kiln on the line A, B, of Fig. 2, and Fig. 2 represents a
sectional plan half on the line C, D, and half on the line E, F, of Fig. 1, a
modified construction of the lower portion of the kiln being shewn at
Fig. 3 in vertical section taken on the line G, H, of Fig. 4, which is a
sectional plan on the line I, K, of Fig. 3.
The upper part of the kiln is domed over or otherwise nearly covered,
leaving a contracted opening' for feeding, which is provided with a slide
or damper or a couple of slides 8, as shewn in Fig. 1, whereby the
For some distance down-
draught through the kiln can be regulated.
wards the interior surface of the kiln is cylindrical or nearly so, and then
it tapers somewhat outwards so as to afford free descent for the contents.
At the bottom is a central pyramid or cone c for the supply of com-
bustible gas and air, as will hereafter be described; the kiln wall from e
somewhat above the apex of this pyramid or cone expands rapidly in
such manner that as the mass of material descending in the kiln is
penetrated and broken up by the cone or pyramid ȧ the increasing
annular space around the latter affords room for the expansion and
spreading out of the material so broken up. Sight holes are provided
in various positions, through which the character of the heat and
draught can be observed.
The internal cone or pyramid c is made of metal or other refractory
material, or its lower part may be of metal with an apex of fire-clay, as
shewn in Fig. 3. Through the sloping sides of the cone or pyramid
separate passages a and 9 are formed for the air and combustible gas
respectively, the orifices of these passages being so arranged that each
The gas
current of gas g has on each side of it a current of air a.

page_text: passages radiate from a chamber 6 within the cone or pyramid, which
chamber is supplied by a pipe or flue ƒ with combustible gas from an
ordinary gas producer, or it may be with the waste gases from a blast
furnace. A portion of the gas may for auxiliary heating be conducted
by an ascending flue / and circular flue / to orifices m opening into the
kiln at the periphery thereof, as described in the Specification above
referred to. The gas supply is regulated by a damper ", and the
auxiliary supply to the orifices m is regulated by a separate damper o.
The air passages a of the cone or pyramid open from a chamber p
underneath, the supply of air being regulated by valves or dampers q.
A. door (of which there may be several when the construction shewn
in Fig. 1 is adopted) is provided to give access to the gas chamber b
from the air chamber p, so that the gas passages and orifices g can be
inspected or cleared out while the kiln remains charged. The cone or
pyramid o is kept comparatively cool by the passage of the air and gas
through it, their mixture and combustion not taking place till after they
have issued into the body of the kiln.
t
For discharging the contents of the kiln a number of openings are
provided at the bottom of the annular space surrounding the cone or
pyramid. These openings are provided with sliding doors or flaps u at
some distance, above which are sliding bars w supporting the contents of
the kiln. The door u being closed the bars 10 above it are withdrawn,
whereupon a portion of the calcined material drops on the door; the
bars to being then replaced the door u can be opened and the portion of
the calcined material withdrawn.
Having thus described the nature of our Invention and in what
manner the same is to be performed, we claim,—
First. The construction of calcining kilns to be worked by gaseous
fuel, in such manner that the combustible gas and air are supplied thereto
in alternate currents through a central cone or pyramid, substantially as
herein described.
Second. In kilns of the kind referred to above, providing a chamber
under the central cone or pyramid for giving access to the orifices
through which the gas and air issue into the kiln, for cleansing or
inspection while the kiln remains charged, substantially as herein
described.

page_text: Third. Constructing kilns of the kind above referred to with an
adjustable opening at the top and with the lower part expanding so as to
afford increasing annular space around the central cone or pyramid,
substantially in the manner and for the purposes herein set forth.
In witness whereof, we, the said Charles William Siemens and 5
Andrew Stein, have hereunto set our hands and seals, this Eighth
day of April, in the year of our Lord One thousand eight hundred
and seventy-five.
Witness,
C. WILLIAM SIEMENS.
ANDW. STEIN.
(L.S.)
(L.S.) 1
JNO. P. M. MILLARD,
20, Southampton Buildings.