Improvements in the Method of Burning Lime, and in Kilns therefor.
Year: 1889

page_text: Date of Application, 23rd Sept., 1889
Complete Specification Left, 19th June, 1890-Accepted, 2nd Aug., 1890
PROVISIONAL SPECIFICATION.
Improvements in the Method of Burning Lime, and in Kilns
therefor.
I, ALFRED BISHOP, of Brockham, Betchworth, Surrey, Secretary of the Brockham
Brick Company, Limited, do hereby declare the nature of niy said invention. for
"IMPROVEMENTS IN THE METHOD OF BURNING LIME AND IN KILNS THEREFOR
to be as follows:-
>>
My invention relates to certain improvements in burning lime whereby I am able to
combine some of the advantages obtained in the old fashioned "flare kilns" with
some of those obtained in kilns worked on the " continuous" system.
According to my invention I construct the kiln preferably of circular plan with its
largest diameter nearer the top than the bottom, and make the kiln taper downwards
towards the bottom where it terminates with fire bars and the usual arrangements
for the removal of the lime. The upper part of the kiln I make dome-shaped, and
prefer that the top of the dome should be just below the surface of the carth. From
the centre of the dome I provide a shaft which I prefer to carry up preferably with
brick work or the like, some little distance above the level of the ground. Into this
shaft the chalk, together with some fuel, is introduced, so that it is kept continuously
filled to about or nearly the level of the top of the shaft.
Round the central shaft, preferably at about equal distances, I construct a series of
feeding shafts, eight is a convenient number, but there may be more or less of them.
These feeding shafts are vertical, or nearly so, and enter the kiln through the dome
just above the part where its diameter is largest. Each of the feeding shafts may be
provided with a metal or other top projecting a short distance above the ground, and
a cap or cover or other means for closing the same, and to admit of the introduction
of fuel.
In burning lime in such a kiln as that just described, the fire being once
established, the process is continuous the chalk being introduced through the central
shaft in such quantity as to keep the shaft filled to the top, or nearly so, and such
chalk may have mixed with it, or inserted alternately with it, some, preferably a
small proportion of fuel. Fuel is also constantly added in small quantities through
the feeding shafts each shaft. being closed immediately after the introduction of each
quantity.
As the fuel is consumed and the chalk converted into lime it passes down the kiln
and is removed at bottom, the removal being so regulated as to keep the hottest part
of the burning mass in or near that part of the kiln having the largest diameter.
That portion of the fuel which is introduced through the small feeding shafts being
deposited near the circumference of the burning mass the flames from it are drawn
inwards towards the centre on their way towards the central shaft and become concen-
trated as they converge and produce a very high temperature with a very moderate
amount of fuel.
The burning of lime in this manner is effected very economically and the lime
produced is very clean and of superior quality.
Dated the 23rd day of September One thousand eight hundred and eighty-nine.

page_text: [
COMPLETE SPECIFICATION.
Improvements in the Method of Burning Lime, and in Kilns
therefor.
دو
I, ALFRED BISHOP, of Brockham, Betchworth, Surrey, Secretary of the Brockham
Brick Company Limited do hereby declare the nature of my said invention for
IMPROVEMENTS IN THE METHOD OF BURNING LIME, AND IN KILNS THEREFOR
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 certain improvements in burning lime whereby 1 am able
to combine some of the advantages obtained in the old fashioned flare kilns" with
some of those obtained in kilns worked on the "continuous" system.
From
According to my invention I construct the kiln preferably of circular plan with its
largest diameter nearer the top than the bottom and make the kiln taper downwards
towards the bottom where it terminates with draw-bars and the usual arrangements
for the removal of the lime. The upper part of the kiln I make dome shaped and
profer that the top of the dome should be just below the surface of the earth.
the central part of the dome I provide a shaft which I prefer to carry up, preferably
with brickwork or the like, some distance above the level of the ground. Into this
shaft the chalk, or limestone, together with some fuel is introduced so that it is kept
continuously filled to about or nearly the level of the top of the shaft.
Round the central shaft, preferably at about equal distances I construct a series of
feeding-shafts which constitute the most important feature of novelty in the kiln,
eight is a convenient number, but there may be more or less of them.
These feeding shafts are vertical, or nearly so, and enter the kiln through the dome
just above the part where its diameter is largest. Each of these feeding shafts may
be provided with a metal or other top projecting a short distance above the ground
and a cap or cover or other means for closing the same and to admit of the introduction
of the fuel.
In order that my invention may be fully understood I shall now proceed to describe
a kiln constructed in accordance therewith and for that purpose shall refer to the
accompanying drawings forming part of this my Specification and to the letters and
figures of reference marked thereon.
Fig. 1 is à plan taken on the level of the draw-bars. Fig. 2 is a vertical section
taken on the line C. D. in Fig. 1. Fig. 3 is a vertical section inken in a plane at right
angles to the preceding one viz. on the line A, B, in Fig. 1. Fig. 4, is a plan taken
above the upper ground-line, and Fig. 5 is a horizontal section taken on the line E, F,
in Fig.2, looking upwards. The foundations of the walls are not shown as they
present no feature of novelty and their structure and size depend chiefly on the usual
considerations of the nature of the soil &c. The line Grepresents the upper ground
level and G the lower ground level, that is to say the level at which the Time is
removed from the kiln. His the wall forming the kiln which attains its greatest
diameter at about the level of the dotted line E, F in Fig. 2, above which it is con-
tracted to form a dome J from the upper part of which is carried up the chimney-
like shaft K. Round the shaft Kare a series of small shifts. m carried up through
the dome to the surface of the ground G above. Each of the shafts m is provided
with a cover or other means of stopping it, this may, conveniently, be arranged by
fitting an iron ferrule or short piece of tubing of the size of the interior of the shaft
within the top of the shaft and so that it projects say 2 inches above the surface of
the ground. A cover is provided to fit loosely over this of such depth as to reach to,
or nearly to, the ground level when placed over the top of the shaft; when in use
some coal dust sand or the like is thrown round the mouth of the shaft so that the
edge of the cover, when the latter is placed over the shaft. dips into the dust and is
thereby, so to speak, trapped sufficiently closely to prevent the escape of the products of
combustion through such shaft and drive the flames up the centre of the kiln. L is a
retaining wall supporting the face of the bank of earth O, in which the kiln is built

page_text: or embedded. P and Q are arches through which access is gained to the bottom of
the kiln. S is set of draw-bars one or more or all of which may be drawn out to
allow the passage of the line into the space T beneath. v. v are two or more sight-
holes usually kept closed at top but enabling the man in charge of the operation from
time to time to inspect the interior of the kiln and thus to judge of and regulate the
heat. n. n. are shafts in the brick-work opening at their lower ends under the arch Q,
and at their upper extremities into the kiln at about half way between the level of the
draw-bars and the plane of greatest diameter of the kiln. These shafts may be con-
trolled by a butterfly or other valve and are generally kept closed but can be opened
when it is desired to increase the vigour of the combustion. W is a platform on
which the chalk and fuel is brought to the top of the kiln.
The kiln is started in precisely the same manner as an ordinary continuous or
draw-kiln and as soon as the fire has reached the level of the line E. F. (Fig. 2), and
the material there has become brightly incandescent the operation is fairly started,
some of the lime is drawn from the bottom, some of the bars S being drawn out to
allow it to pass, and as the whole mass sinks, more chalk and some fuel, preferably
coke or culin, is added at the top, say, about 30 pounds of broken coke of culm to
each yard of chalk or limestone keeping the kiln full to the top of the shaft K or
nearly so, and so that the chalk, after it is shot in, is gradually dried and heated as it
slowly finds its way down the shaft K. At frequent intervals, say about every fifteen
minutes, an attendant lifts the covers of the feeding-shafts one by one, and puts into
each a supply of fuel siftings of the best house-coal, in small quantities, say, about a
quart at a time, immediately closing each shaft with its cover. This fuel falling on
the incandescent mass is speedily brought into vivid combustion, the flames being
drawn towards the centre of the kiln and up towards the central shaft. By the time
the lime reaches the lower part of the kiln it is usually sufficiently cool to be handled,
and is removed in barrows or trucks, and as the lime is drawn away from below, the
contents of the kiln gradually sink bodily, its place being continually supplied by
additions at the top In this way the operation when once started is continuous, the
withdrawal at bottom and the supplying at top constantly going on.
Such a kiln as I have described and represented will produce about 100 yards of
lime per week, more or less, but the same principles of construction and similar
arrangement may be applied to kilns of larger or smaller capacity, and although 1
have given some general directions as to the supply of fuel in the kiln hereinbefore
described which I have found to be advantageous the same may be varied according
to circumstances, and I make no claim to any specific proportions of fuel to the chalk
or limestone operated upon.
The burning of lime, in this manner, is very economical and the lime produced is
very clean and of superior quality and colour.
Having now particularly described and ascertained the nature of my said inven-
ion and in what manner the same is to be performed I declare that what I
claim is:
1. Constructing lime-kilns with a series of feed-holes, or shafts, by means of
which fuel is supplied substantially in the manner and for the purpose set forth.
2. Constructing lime-kilns with a long shaft at top in which the chalk, or limestone,
s as it slowly descends, dried and warmed before being actually burned, and with
eed holes or shafts substantially as described and shown in the drawings.
3. The construction and use of lime-kilns substantially as described and shown.
4. The method of burning chalk, or limestone, into lime substantially as described
nd set forth.
5. The method of burning chalk, or limestone, into lime by means of a kiln having
ealing-holes for supplying fuel at or near the level of the most intense heat which is
bout that of the greatest diameter of the kiln substantially as described.
Dated the 19th day of June 1890.
ALFRED BISHOP.