6 IMPROVEMENTS IN THE CONSTRUCTION OF KILNS FOR BURNING " LIMESTONE
Year: 1883

page_text: LETTERS PATENT to John Briggs of Buxton in the County of Derby for an
Invention of
"6
IMPROVEMENTS IN THE CONSTRUCTION OF KILNS FOR BURNING
"
LIMESTONE
PROVISIONAL SPECIFICATION left by the said John Briggs at the Office
of the Commissioners of Patents on the 13th October 1883.
JOHN BRIGGS of Buxton in the County of Derby
CONSTRUCTION OF KILNS FOR BURNING LIMESTONE
"
"IMPROVEMENTS IN THE
The kiln is open at the top and is made with a contraction or neck at or near
the centre and with a door at the lower end.
On each side of the neck is an arched passage provided with rolled plate glass
windows to admit light.
These arched passages are entered by an archway from the outside.
From these passages air pipes pass through the walls into the neck of the
furnace to admit air and between the air pipes are a series of retorts for the
conversion of slack coal into coke, the gas driven off in the process passing into
the furnace direct from the retorts. At the bottom of the neck are steam pipes
for the admission of dry superheated steam.
The limestone to be burnt or calcined is brought in tram-wagons and poured
into the top of the kiln, no levelling setting or packing being required, and the
limestone then descends without any fuel whatever being mixed with it, thereby
producing good clean lime.
When the limestone arrives at the neck of the furnace, flame is produced by the
admission of air, gas, and dry superheated steam, from the pipes and retorts
respectively.
The retorts are filled with coal or slack by the firemen working in the arched
passages, after which the mouth of the retorts is tightly screwed up, and the heat
of the material in the kiln drives off the gas out of the coal or slack in the
retorts, and the gas thus produced passes into the neck of the kiln and rising
upwards amongst the red hot limestone which causes it to burst into flame, and
the air entering at the points where the combustion takes place increases the heat,
Dine S71

page_text: owing to the oxygen of the air being a far better supporter of combustion than
carbonic oxide which is produced when all the air enters at the bottom of the kiln
as in those ordinarily employed. The air pipes also act as sight holes for the
fireman so that he may inspect the state of the fire in the kiln and regulato it
accordingly.
This arrangement is of great value as the amount of fuel required is much less
than if all the air entered at the bottom of the kiln as in the old system.
When all the gas has been driven off the slack or coal in the retorts, coke
remains, which can be removed and sold at market value:
The archways are supplied with ventilating pipes passing out through the walls
of the kiln to carry away foul heated air.
The dry superheated steam will be found much superior, for lime burning
purposes, to steam in its ordinary state as it will not burst or crack the lime as
steam at 212 degrees Fahrenheit will do if admitted into the kiln. The steam
may be dried and superheated for this purpose in any suitable manner, but I prefer
to effect this by conveying the steam through a serpentine pipe passing the boiler
and leading to the steam pipes in the neck of the kiln.
The lime gradually descends to the bottom of the kiln cooling as it falls and as
the distance between the neck (where the greatest heat is) and the bottom is some
yards the lime is always cold when drawn from the kiln."
"cobs
At the bottom of the kiln is the kiln door through which the lime is drawn off
over a screen and the large pieces or
pass down slides direct into the
railway trucks which are placed beneath.
The small lime falls through the screen into a chamber formed beneath it for
that purpose. This chamber will hold from ten to twelve tons of small lime and
is provided with doors through which it can be emptied from time to time as may
be required.
Space is provided on each side of the small lime chamber for unburnt limo or
"bull heads" and when these spaces are full they can be emptied in the same
manner.
In constructing this kiln the space between the fire brick lining and the outside
of the kiln must be well puddled and rammed with clay or fox earth which the
heat of the kila will burn into a solid mass so that in case of a few fire bricks
being burnt out or otherwise damaged the backing will remain in its proper place
and the work can be repaired without difficulty. In addition to which the clay
and fox earth when once heated will save a great amount of fuel, as it does not
allow any heat to make its way outwards through the sides of the kiln but forces
it to escape upwards in the direction required.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Briggs in the Patent Office on the 10th April 1884.
JOHN BRIGGS of Buxton in the County of Derby
CONSTRUCTION OF KILNS FOR BURNING LIMESTONE
"
"IMPROVEMENTS IN THE
The object of this invention is to construct a kiln for burning limestone (which
is also applicable for other calcining purposes such as for calcining ores or cement)
by means of a gas evolved from slack coal during its conversion into coke whereby
a considerable economy in the consumption of fuel is effected, and the lime thereby
produced is in large lumps or pieces and better and cleaner than can be produced
by the usual method of mixing the fuel with the limestone.
Such being the nature and object of my said invention I will now proceed to
describe in detail the manner in which the same is to be or may be performed or
carried into practical effect and in order that the same may be clearly understood
I have annexed hereunto a sheet of drawings illustrative thereof and have marked
the same with figures and letters of reference corresponding with those in the
following explanation thereof.
Fig. 1. in the annexed drawing is a longitudinal section taken vertically through
a kiln constructed according to my invention and Fig. 2. is a transverse section of
the same taken through the line A. B.
The kiln is open at the top a, a and is made with a contraction or neck b, b at
or near the centre and with a door or doors c, c at the lower end.
On each side of the neck b, b is an arched passage d, d provided with rolled plate
glass windows to admit light. These arched passages are entered by an arch way
from the outside.
From these passages d, d air pipes e, e pass through the walls into the neck b, b
of the furnace to admit air, and between or beneath the air pipes are a series of
retortsff for the conversion of slack coal into coke the gas driven off in the
process passing into the furnace direct from the retorts. The air pipes are
preferably cast or made in one piece with the retorts. At the bottom of the
neck b, b may be placed steam pipes g, g for the admission of dry superheated
steam.
The limestone to be burnt or calcined is brought in tram-wagons and tipped or
poured into the top of the kiln, no levelling, setting or packing being required,
and the limestone then descends without any fuel whatever being mixed with it
thereby producing good clean lime. On first firing a kiln however it is necessary
to mix fuel with the limestone in the lower chamber h, h in the ordinary manner
and when the combustion reaches the central chamber b, b calcination is retained
at that point so long as the kiln remains in use.
When the limestone arrives at the neck b, b of the kiln, flame is produced by
the admixture of air and gas (with or without dry superheated steam) from the
pipes e, e and retorts f, f respectively
The retorts f, fare filled with coal cannel 'burgy' or slack by the firemen
working in the arched passages d, d after which the mouths of the retorts f, f are
tightly screwed up and the latent heat of the material in the kiln drives off the
gas out of the coal or slack in the retorts f, f and the gas thus produced passes into
the neck b, b of the kiln and rising upwards amongst the red hot limestone which
causes it to burst into flame, and the air entering at the points where the combus-
tion takes place increases the heat, owing to the oxygen of the air being a far
better supporter of combustion than carbonic oxide which is produced when all
the air enters at the bottom of the kiln as in those ordinarily employed. The air
pipes e, e also act as sight holes for the fireman so that he may inspect the state of

page_text: the fire in the kiln and regulate it accordingly i, i are openings (provided with
covers) to admit fuel should the kilns be allowed to go out at any time and also to
get up extra heat should the same be found necessary.
This arrangement of kiln is of great value as the amount of fuel required is
much less than if all the air entered at the bottom of the kiln as in the old
system.
When all the gas has been driven off the slack or coal in the retorts f, f, coke
remains which can be removed and sold at market value.
The archways d, d are supplied with ventilating pipes k, k passing out through
the walls of the kiln to carry away foul heated air.
The dry superheated steam will be found much superior for lime burning
purposes, to steam in its ordinary state as it will not burst or crack the lime, as
steam at 212 degrees Fahrenheit will do if admitted into the kilo.
The steam may be dried and superheated for this purpose in any suitable manner
but I prefer to effect this by conveying the steam through a serpentine pipe
passing through the boiler and leading to the steam pipe in the neck b, b of
.the kiln.
The lime gradually descends to the bottom of the kiln cooling as it falls and as
the distance between the neck d d (where the greatest heat is) and the bottom is
some yards the lime is always cold when drawn from the kiln.
"
At the bottom of the kiln is the kiln door or doors c, c through which the lime
is drawn off over a screen 1, 7 and the large pieces or cobs" pass down slides m, m'
direct into the railway trucks which are placed beneath.
The small lime falls through the screen into a chamber n, n formed beneath it
for that purpose. This chamber will hold from ten to twelve tons of small lime
and is provided with doors through which it can be emptied from time to time as
may be required.
A
Space may be provided on each side of the lime chamber (see dotted lines o, o
in Fig 2.) for unburnt lime or "bull heads" should any happen to be found among
the burnt lime, and when these spaces are full they can be emptied in the same
manner.
In constructing this kiln the space between the fire brick lining and the outside
of the kiln must be well puddled and rammed with clay or fox earth, which the
heat of the kiln will burn into a solid mass, so that in case of a few fire bricks
being burnt out or otherwise damaged, the backing will remain in its proper place
and the work can be repaired without difficulty. In addition to which the clay'
and fox earth when once heated will save a great amount of fuel, as it does not
allow any heat to make its way outwards through the sides of the kiln but forces
it to escape upwards in the direction required.
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 to be
understood that I claim.
The general construction and arrangement of the kiln as hereinbefore described
and illustrated by the drawing annexed, whereby I am enabled to use the latent
heat of the burning lime after passing the calcination point, to heat retorts charged
with coal, cannel burgy, or slack, and to utilize the gas evolved from the latter as
fuel to effect the calcination of the lime.
In witness whereof I the said John Briggs have hereunto set my hand and
seal this eighth day of April in the year of our Lord one thousand eight hundred
and eighty four.