IMPROVEMENTS IN KILNS FOR CALCINING LIMESTONE
Year: 1868

page_text: LETTERS PATENT to John Russell Swann, of 21, Leith Walk,
Edinburgh, for the Invention of "IMPROVEMENTS IN KILNS FOR
CALCINING LIMESTONE."
Sealed the 11th May 1869, and dated the 4th December 1868.
PROVISIONAL SPECIFICATION left by the said John Russell Swann
at the Office of the Commissioners of Patents, with his Petition,
on the 4th December 1868.
I, JOHN RUSSELL SWANN, of 21, Leith Walk, Edinburgh, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN KILNS FOR
CALCINING LIMESTONE," to be as follows:-
This Invention has for its object improvements in kilns for calcining
limestone.
In order to obtain a more perfect combustion of fuel without smoke
and with economy of labour I apply to kilns moveable or travelling
fire-bars. The fire-bars are received into a chamber at the bottom of
the kiln, over which a dry limestone arch is turned, through the
openings or crevices in which the heat from the fire passes up into the

page_text: kiln. Machinery is provided for driving the fire-bars, and doors are
provided in connection with such fire-bars for admitting air. The fire-
bars can be drawn out of the kiln while it is cooling and being emptied,
and the same bars may be put immediately into another kiln. The
contents of the kiln after firing and when cool are drawn by removing
the arch, which allows the charge to descend, and the dry arch is rebuilt
before recharging the kiln. A blast of heated air may advantageously
be used to dry and heat the charge before firing. A further advantage
is gained by using such fire-bars, as the kilns can be more rapidly arched
in filling and emptying. One set of such fire-bars arranged in the
manner proposed will be sufficient for working two or more kilns.
I prefer to arrange the kilns at different levels in such manner that the
waste heat from the top of the lower kiln may be passed into the bottom
of the upper kiln without its being necessary to-lead the draft down-
wards, as would be requisite if the kilns were on the same level. The
kilus will usually be constructed in two sets at upper and lower levels,
and in such manner that two kilns of the upper row can receive the
heat from one kiln of the lower row. In some cases instead of supplying
thic fires of the lime kilns-with-cold air, as is now universally the practice,
I supply them with heated air in suitably regulated quantity to maintain
combustion.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Russell Swann in the Great Scal Patent
Office on the 4th June 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JONN
RUSSELL SWANN, of No. 21, Leith Walk, Edinburgh, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourth day of December, in the year of our
Lord One thousand cight hundred and sixty-eight, in the thirty-second
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said John Russell Swann, Her special licence that
I, the said John Russell Swann, my executors, administrators, and
assigns, or such others as I, the said John Russell Swann, my execu-
tors, administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term

page_text: and provided with a feeding hopper with a regulating door or slide. No
detailed description of these fire-bars and the parts connected therewith
is requisite, as they are such as are known as Juckes' fire-bars; they
have heretofore been employed in combination with steam boilers; other
arrangements of travelling fire-bars mounted on a carriage may also be
employed. d is the flue of the kiln; it is provided with a damper to
regulate the draft, or by closing this damper the heated gases may be
turned into the side flues e, e, and passed into other kilns, as herein-after
described. ff, are pipes or flues which may be built in the sides a, a,
of the kiln, and air may be forced through them by a fan driven by a
steam engine; the same power may drive the re-bars, so as to cause
them to travel at a slow speed by means of the driving band g and
suitable gearing. It will be observed that small limestone is sa
distributed over the surface of the charge in the kiln-as-to cause every
part, as far as possible, to be exposed to the same degree of heat, and care
is taken in firing the kiln to maintain a proper heat as has heretofore
been requisite. The air heated in the pipes f is led away to another
kiln by suitable pipes, and is there used in drying the charge in such
kiln before firing; it is introduced under the arch to receive the fire-bars,
which is then temporarily enclosed at the front where the firc-bars arc
introduced by a rough wall. I prefer to arrange the kilns at different
levels in such manner that the waste heat from the top of the lower kiln
may be passed into the bottom of the upper kiln without its being
necessary to lead the draft downwards as would be requisite if the kilns
were on the same level. The kilns will usually be constructed in two
sets at upper and lower levels, and in such manner that two kilns of the
upper row can receive the heat from one kiln of the lower row.
Figure 2 is a front view of a series of kilns thus arranged; they
may be fitted with travelling fire-bars as above described or otherwise.
It will be seen that the side flues (e, Figure 1) of the kilns of the lower
row pass to the bottoms of kilns of the upper row. The side flue is
inserted into the fire space or chamber of the upper kiln, which is
temporarily closed up at the front by a wall when the draft is thus
directed. In this way the heated gases from the lower kiln may be
directed into one or other of the two upper kilns with which it is con-
nected, and this is done when such upper kiln has been newly charged to
dry the charge before the firing is commenced.
In some cases instead of supplying the fires of lime kilns with cold

page_text: air, as is now universally the practice, I supply them with heated air
in a suitably regulated quantity to maintain combustion.
Figure 3 is a vertical section of a pair of kilns of the construction
known as draw kilus arranged to be worked with heated air, as above
described.
a, a, is the brickwork or masonry of the kilns with the usual arches
at the bottom for drawing the lime and an opening or mouth at the
top for charging, which, however, I prefer to cover with a boiler plate
hood with a damper at the top in order the better to regulate the draft.
The hood has a door or doors in it at the side for charging in the lime-
stone, and the fuel and the hood may for convenience be made to turn
on rollers. Between the kilns is a chamber b, which will be to some
extent heated by the kilns, and is further heated by a furnace at the
bottom, over which an open arch is turned. The products from the
furnace after heating the chamber bare led into the kilns by passages or
flues b, b, having dampers so that the workman may direct this hicat
into one kiln or the other, as the working of the kilns at the time may
render desirable. c, c, are pipes into which air is forced by a fan; they
arc built into the brickwork or masonry, and are to some extent heated
from the kilns; from them the air passes into pipes c¹ in the heated
chamber b, and these again lead the air which is now highly heated into
pipes c, which encircle the bottom of each kiln with two coils, which
are perforated to allow the hot air to escape from them into the kiln to
support combustion therein.
In place of heating the air as above described it may be heated by a
separate stove or otherwisc.
Having thus described the nature of my said Invention, and the
manner of performing the same, I would have it understood that what I
claim is,―
First. The constructing kilns for calcining limestone with travelling
fire-bars, as described.
Second. The constructing kilns for calcining limestone in scts at
different levels in such manner that the heat and products of combustion
may be led from a kiln at a lower level into a kiln at a higher level to
dry the charge therein, as above described.
Third. The combining with kilns for calcining lime apparatus for

page_text: supplying such kilus with heated air in such manner as to support the
combustion of the fuel in the kilns, as above described.
In witness whereof, I; the said John Russell Swann, have here-
unto set my hand and seal, this First day of June, in the year
of our Lord One thousand eight hundred and sixty-nine.