IMPROVEMENTS IN KILNS FOR CALCINING LIME, CEMENT, ORES, AND SIMILAR MATERIALS
Year: 1878

page_text: LETTERS PATENT to Edward Crosland, of Leeds, in the County of York, Civil
Engineer, for the Invention of "IMPROVEMENTS IN KILNS FOR CALCINING
LIME, CEMENT, ORES, AND SIMILAR MATERIALS."
Sealed the 13th June 1879, and dated the 20th December 1878.
PROVISIONAL SPECIFICATION left by the said Edward Crosland at the
Office of the Commissioners of Patents on the 20th December 1878.
EDWARD CROSLAND, of Leeds, in the County of York, Civil Engineer. "IM-
IN KILNS FOR CALCINING LIME, CEMENT, ORES, AND
PROVEMENTS
MATERIALS."
دو
SIMILAR
My Invention relates to kilns for calcining lime, cement, plaster, ores, and similar
materials by the combustion of gaseous fuel, and consists in improvements in that
class of kilns described in the Specifications of Letters Patent granted to Charles
William Siemens, the 21st day of August, A.D. 1867, No. 2395, and Letters Patent
granted to Charles William Siemens and Andrew Stein, the 9th day of October,
A.D. 1874, No. 3457.
But my Invention affords the means for working such kilns to much greater
advantage than has heretofore been practicable.
According to my said improvements, the gaseous fuel is consumed within the
kiln without any cooling whatever, but on the contrary, at the highest degree of
heat at which it is possible to generate it, the advantages being as follows, that is
to say, I save or economize the heat necessarily extracted before passing through
the valves and cones described in the aforesaid Specifications; and I dispense with
the flues connecting the kiln with the gas producer, also with the metal work and
valves throughout the kiln.
I carry my said improvements into practice as follows, that is to say :-
The general construction of the kiln is somewhat similar to that of an ordinary
lime kiln, but instead of feeding solid fuel along with the lime, I provide a gas-
producer or close fire near the bottom and within the kiln. The gas generated has

page_text: therefore only to pass through holes provided in the wall dividing the gas-producer
from the kiln proper, a distance not necessarily more than a few inches. The said
gas-producer may be built at one side of the kiln, or may be built in the centre,
the roof forming a dividing bridge for the lime as the latter descends, causing it to
be divided into two or more channels. In the first case, that is to say, if built
at the side, access to the said gas-producer would be obtained either opposite the
discharging door, or immediately on either side of that point. And in the second
case, that is to say, if built in the centre, the gas-producer may be formed to extend
through the kiln, access being obtained on either side, and the body of material to
be calcined being divided into two main channels with exit or discharging doors on
either side of the said gas-producer.
'
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edward Crosland in the Great Seal Patent Office on the 19th June
1879.
EDWARD CROSLAND, of Leeds, in the County of York, Civil Engineer. "IM-
PROVEMENTS IN KILNS FOR CALCINING LIME, CEMENT, ORES, AND SIMILAR
MATERIALS."
My Invention relates to kilns for calcining lime, cement, plaster, ores, and similar
materials, by the combustion of gaseous fuel, and consists in improvements in that
class of kilns described in the Specifications of Letters Patent granted to Charles
William Siemens, the 21st day of August, A.D. 1867, No. 2395, and Letters Patent
granted to Charles William Siemens and Andrew Stein, the 9th day of October
A.D. 1874, No. 3457.
,
For the heating or calcining of the materials manufactured, I use gas of a similar
nature to that used in iron works' furnaces, but with the difference that the gas as
generally used in the iron and steel processes is of low temperature when entering
the furnace, while as used by me, it is introduced directly into the shaft or kiln at
a temperature equal, or very nearly so, to that at which it is produced. Thus, a
saving is effected by a minimum length of gas passage; consequently, there will be
a minimum loss of heat by conduction and radiation therefrom, and for the same
reason, the gas is delivered into the kiln at a maximum temperature. A further
saving of time and fuel is effected by this maximum temperature preventing the
condensation and deposit of any of the hydro-carbons as would otherwise occur,
therefore there is no necessity for so frequent cleaning of the passages, and con-
sequently the stopping of the process while such is effected, the only deposit being
a little dust-ash which can be rolled out of holes provided for the purpose without
much interference with the operation of the kiln.
The gas producer I place at no greater distance from the kiln than the thickness
of a wall, only sufficiently substantial to stand the wear and tear from the materials

page_text: treated, and the heat necessary for the process at a height some distance from the
bottom, and in a position as much under the charge as possible to ensure the flame
passing through every portion of the material under treatment, thus the kiln may
be symmetrically vertical; it may have an inclining annular space above the gas-
ports, or the whole may lean over the producer as shewn in the Drawing. The
lower part of the upper portion of the shaft just above the belt is by preference
made sloping for two reasons; firstly, to cause the descending materials to roll
and change place, and, secondly, to cause the draught and flame to cross the kiln
on its ascent, thus insuring a thorough intermixture of the materials and distri-
bution of the heat throughout the charge as it descends, and causing great
perfection of work.
From the gas chamber or producer I form ports or openings through the wall,
dividing it from the kiln for the gas to pass through. A flue also may be carried
from the top of this gas-chamber partially or entirely around the kiln, forming a belt
in such a way as to allow of ports or openings being made for the passing of the
gas into the kiln at any point of the circumference desired. The ash-pit of the gas-
producer may be fitted with doors so as to regulate the supply of air thereto either
for checking the production of gas by limiting the supply of air, or for increasing
the production by applying a forced draught as circumstances may demand.
In further description of my Invention, and referring to the accompanying
Drawing, Figure 1 is a vertical section through the kiln and gas-producer, of an
arrangement with a single or inclined shaft. Figure 2 is a half horizontal section
or plan through the discharging door at the bottom of the shaft, shewing how the
air may be introduced either by the natural or forced draught. Figure 3 is a half
horizontal section or plan through the gas-producer below the fire-bars, shewing the
doors by which the generation of gas may be regulated, and the air-passages by
which air, may be forced, and the generation of gas increased. Figure 4 is a
horizontal section or plan through the belt, shewing the gas passages and upper
part of producer.
The same letters indicate corresponding parts throughout the Drawing.
T is the top of the shaft or kiln into which the materials to be calcined are
tipped or dropped. S is the upper portion of the shaft in which the materials are
heated. B is the belt of gas-ports, about and above which the materials are
brought to their maximum heat, and the consumption of gas and air takes place.
O, O, are the openings or ports for the passage of the gas, and F is the flue in
which it is conveyed from P the producer; D', D', are the feeding doors of the
producer. C, C, are clearing holes for the purpose of clearing the dust from the
flues and ports, and watching the process, but are closed as a rule. B are the fire-
bars, and A is the ash-place into which are introduced the blast flues F if necessary.
D³, D2, are the ash pit doors for regulating the generation of gas as before described.
Lis the lower portion of the kiln-shaft in which the calcined material is cooled in
its descent by the ascending air. D is the discharging door through which the
finished materials are drawn from the kiln. B³ is the bottom blast flue used for the
introduction of the air to the kiln, either by the natural draught or a forced blast,
but which may not be necessary in some cases, the discharging door being available
where the natural draught is sufficient. P¹, P¹, are the air ports connecting the
bottom blast flue with the shaft of the kiln.
The process of calcining and working of the kiln is as follows, namely:-The raw
material is put in at the top of the kiln, preferably at constant and regular intervals.
As it descends the upper portion of the shaft, it absorbs the waste heat, ascending
from the hotter materials below, so that little or no heat is emitted and lost at the
top.
The material having arrived near the belt comes to the most active part of the
kiln, and there undergoes the finishing heat obtained as described in the following
clause. Descending down the lower part of the shaft, it is cooled by the ascending
draught, and may be drawn out at the bottom comparatively cold.
The air entering at the bottom absorbs the heat of the calcined material, and

page_text: arrives at the belt at a very high temperature. The gas as before described being
introduced at this point also at a high temperature, and the materials also being at
a high temperature when arriving near this point, the result under such circum-
stances of the combustion of the gas and air is the creation of a very intense heat, and
a very perfect combustion not hitherto attainable by the "Hoffman," the "Siemens,"
or any other kiln designed with the same object, with the same degree of economy
and perfection of work.
Having thus stated the nature of my Invention, and described the manner of
performing the same, I wish it to be understood that I do not intend to limit
myself to the details given, so long as the peculiar character of the Invention be
retained, and I claim,--
The improvements comprising the arrangement whereby I provide the kiln with
the gas producer which is separated from the kiln by only a comparatively thin
partition or wall, through openings in which the gas flows, at or near the temperature
at which it is made, and which arrangement may be employed either in combination
or not with the non-vertical form of part of the shaft of the kiln at or above the
belt, as and for the purposes above set forth.
In witness whereof, I, the said Edward Crosland, have hereunto set my hand
and seal, this Seventeenth day of June, in the year of our Lord One thousand
eight hundred and seventy nine.
EDWARD CROSLAND. (L.S.)
Witness,
JOHN A. CROSLAND.