IMPROVEMENTS IN LIME AND OTHER KILNS
Year: 1869

page_text: LETTERS PATENT to Henry Young Darracott Scott, of Ealing, in the
County of Middlesex, Lieutenant-Colonel Royal Engineers, for the
Invention of "IMPROVEMENTS IN LIME AND OTHER KILNS."
Sealed the 2nd July 1869, and dated the 30th March 1869.
PROVISIONAL SPECIFICATION left by the said Henry Young Darracott
Scott at the Office of the Commissioners of Patents, with his
l'etition, on the 30th March 1869.
1, HENRY YOUNG DARRACOTT SCOTT, of Ealing, in the County of
Middlesex, Lieutenant-Colonel Royal Engineers, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN LIME AND OTHER KILNS,"
to be as follows:-
The objects of this Invention of improvements in lime and other kilns
are the calcination of such minerals as limestone, chalk, cement, stones,
and cement mixtures, iron and zinc ores, and other analogous substances
by an economical and efficient process. The production of the material
known as "Scott's cement," is also effected by means of this Invention
in a more direct and economical manner than is now practised.
1

page_text: In carrying out my Invention I arrange any convenient number of
vertical compartments side by side. Each compartment consists of three
divisions or chambers situated vertically one above the other, and com-
prises, 1st, a cooling chamber at the lower part of the kiln, into which
the mineral after it has been calcined by the heat is made to descend
preparatory to being withdrawn from the kiln; 2nd, a chamber in which
the calcination of the substance is effected; 3rd, a chamber in which
the mineral is subjected to a preparatory heating, and is raised to a
fitting temperature before its descent to the calcining chamber. The
division walls between the compartments, and also the containing walls
at each end of the series are perforated with openings, through which
the products of combustion from the fires which supply the heat are
made to traverse horizontally across the vertical compartments through-
out the whole length of the kiln in its central zone, between the levels of
the tops of the cooling chambers, and the bottom of the upper or heating
chambers. The fires are arranged at one end of the series of calcining
chambers, and are adapted for burning thick layers of fuel and for the
production of combustible gases therefrom. 1 employ by preference a
form of fire-place which admits of the separate treatment of those
constituents of the fuel which admit of volatilization and those which
are fixed.
I sometimes consume the latter in part by the oxygen
derived from the decomposition of vapour of water, and sometimes mix
the coke which results from the volatilisation of the gases of the coal
with the mineral to be calcined. A chimney stack is placed at the
opposite end of the series of calcining chambers to create a draught
through the chambers when required. In order to consume the com-
bustible gases produced from the fires inlet holes are made in the cheeks
of the openings of the division and containing walls so as to admit fresh
air into the kiln as may be required to calcine the contents of one or the
other of the compartments composing the series. Each vertical com-
partment is furnished with an orifice at the top, which may be opened or
closed at will, and through these orifices fresh mineral is introduced into
the several vertical compartments. The cooling chamber of each com-
partment is also provided with a draw hole or holes at the bottom
through which the calcined mineral is to be withdrawn at proper
intervals. The firing doors are sometimes perforated to admit fresh air
for consuming the gaseous fuel used for the calcination of the contents
of the first compartment next the fires. Spy holes are employed to
watch the temperature and regulate the progress of the calcination.

page_text: In the preparation of "Scott's cement," after each period of firing,
and when a charge has just been withdrawn, sulphur or sulphur ores, or
brassy coal, or other substances capable of yielding sulphurous acid by
ignition in the air are consumed beneath the cooling chambers, and by
means of suitable passages and a proper draught the sulphurous acid
thus formed is led up through the heated lime and acts upon it so as to
convert it into "Scott's cement" in the well-known manner. The heat
of the mineral of which the calcination has been completed is made
subservient to drying and heating the fresh mineral introduced into the
upper chambers.
This is effected by stopping the draught of the
chimney stack and opening the upper orifices of the various compart-
ments at suitable intervals. Indraught holes are at the same time also
opened in the cooling chambers. I sometimes introduce coal intermixed
with the mineral at the orifices at the tops of the compartments, and I
may then dispense with the fire-places. Inlet holes at proper parts of
the compartments, as above described, admit fresh air to assist in the
combustion of the fuel. The process may also be carried out with two
compartments only, one of which contains the mineral and the fuel
intermixed, and the other containing generally mineral only, or mineral
with a much smaller proportion of fuel is used in lieu of the chimney.
The first is kept closed, excepting when the kiln is being loaded, and the
two compartments communicate below, so that the volatile products
distilled from the coal may be forced through the second compartment,
and be made to encounter streamlets of fresh air introduced as described,
which consume both them and the fixed constituents of the fuel. One
compartment of the kiln may be enclosed within the other, instead of
their being arranged side by side, and that which acts as chimney may
with advantage be higher than the other.
30
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Young Darracott Scott in the Great Seal
Patent Office on the 30th September 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
YOUNG DARRACOTT SCOTT, of Ealing, in the County of Middlesex,
Lieutenant-Colonel Royal Engineers, send greeting.

page_text: .
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirtieth day of March, in the year of
our Lord One thousand eight hundred and sixty-nine, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Henry Young Darracott Scott, Her
special licence that I, the said Henry Young Darracott Scott, my
executors, administrators, and assigns, or such others as I, the said
Henry Young Darracott Scott, my 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 LIME AND OTHER KILNS,"
upon the condition (amongst others) that I, the said Henry Young
Darracott Scott, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should
particularly describe and ascertain the nature of the said Invention,
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 I, the said Henry Young Darracott Scott,
do hereby declare the nature of my said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the Drawing
hereunto annexed, and to the letters and figures marked thereon (that is
to say):-
My Invention consists of improvements in the construction and
arrangement of kilns or ovens for burning lime, cement, bricks, and
other substances of analogous character, whereby a larger quantity of
heat as compared with the fuel consumed is made available than by
the processes now used.
«
In the following description of the Invention I wish it to be under-
stood that by the term compartment" I mean one whole section of
the kiln situated between the containing walls of such section, and
that by the term "chamber" I means a portion of one of the com-
partments having a perfectly definable office though not separated from
the contiguous portions by any material boundary.

page_text: "
In carrying out my Invention I arrange any convenient number of
compartments in a series, side by side. Each compartment consists of
three divisions situated vertically one over the other, and comprises
first, a cooling chamber at the bottom into which the substances
operated upon descend after their calcination, and whence they are
finally withdrawn; second, a middle chamber in which the substances
to be operated upon are subjected to the degree of heat necessary for
their calcination; third, a chamber in which these substances are
subjected to a preparatory heating to expel moisture and raise them to a
fitting temperature before they descend to the central chamber for
calcination. These chambers will hereafter be termed for brevity's' sake
the "cooling," calcining," and "smoking " chambers. A chimney
provided with a damper terminates the end of the series of compart-
ments. The division walls between the compartments and also the
end wall next the chimney are perforated with openings through which
the gaseous products of combustion traverse the compartments through
the calcining chambers in a generally horizontal direction between the
levels of the tops of the cooling chambers and the bottoms of the
smoking chambers. Where the mixture of the fuel with the minerals
is objectionable the furnaces or fire-places are placed at one end of
the series of calcining chambers, and are so constructed and fed as
to yield for the most parts carbonic oxide and hydrocarbon gases which
may be burned in each compartment in succession or simultaneously.
The furnace best adapted for this form of treatment is shewn in
Figs. 7, 8, and 9 of the accompanying Drawing in which the volatile
gases are expelled in an upper chamber 1 and are led through proper
flues 2 to exits below the exit 3 for the other products of combustion
from the fire-place a. The coke resulting from the expulsion of the
gases.of the coal is drawn down from the chamber 1 into the furnace a,
where its combustion will be completed. Or instead of this arrange-
ment the coke may be withdrawn altogether from the coking chamber 1
and be introduced through the opening d and mixed with the mineral
to be calcined. This method of treating the fuel in itself effects a
considerable saving and is applicable even to kilns consisting of one
chamber only..
In order to consume the combustible. gases produced
by the fires in. each compartment in succession inlet holes are made
as at.b, for a supply of atmospheric air at each of the division walls,
and also at various parts of the kiln as at o, o, o, in the Drawings, par-

page_text: licularly at the bottom of the cooling chamber, so that the air may
be warmed before it comes in contact with the combustible gases
produced by the fires a, and at the same time (and by its means) the
fully calcined mineral will be cooled. Each compartment consisting
of the chambers X, Y, Z, is furnished with an orificed at the top,
which may be opened or closed at will, and through these orifices fresh
substances to be operated upon are introduced. The cooling chamber Z
of each compartment is provided with a draw hole or holes c (at the
sole of the kiln) through which the substances that have been operated
on are withdrawn at proper intervals. The heat of the mineral of
which the calcination has been completed, is made directly sub-
servient to drying and heating the fresh minerals introduced into the
smoking chambers X.
This is effected by stopping the draft into the
chimney stack and opening the orifices d of the smoking chamber X,
and the holes cat the bottom of the cooling chambers Z at proper
intervals. By this means the draught will be made from time to
time to set upwards carrying the heat from the cooling and cal-
cining chambers Z and Y through the mineral to be dried in X. In
ordinary cases of lime burning (and where the admixture of the fuel
with the mineral has not been considered so objectionable as to induce
manufacturers to use the flare principle of burning lime and bricks)
the process of charging is carried out very much as with an ordinary
tunnel or running kiln. The draught, however, is not allowed to take the
direct upward course out at the openings at the top of the kiln excepting
during the smoking process, so as to get rid of superabundant moisture.
At all other times the orifices d at the top of each compartment are
closed with their moveable lids or covers, and the general direction
of the draught then becomes horizontal throughout the whole series
of calcining chambers to the chimney which terminates them. The
draught may, however, manifestly have given to it (in this as in the
other cases I have to describe) a direction somewhat inclined to the
horizon without departing from my Invention. The first compartment
of the series is supplied with more fuel than the others, the excess being
placed chiefly on the side farthest away from the chimney, and when
coals rich in hydrocarbons are employed the alternate compartments
are charged with a less proportion of fuel than their neighbours, or if
the compartments are shallow in the direction of the series the alternate
compartments are charged with mineral only. The kiln above referred
to is shewn in vertical section at Figures 1, 2; Figs. 3, 4, and 5 are

page_text: The
horizontal sections of the same taken in different planes as indicated
in the Drawings. The process may be carried out (though with some
loss of efficiency) with two compartments only, one of which is heated
by external fires, or may contain the mineral and the fuel intermixed.
The other compartment (containing generally mineral only or mineral
with a much smaller proportion of fuel) is used as a chimney, and with
this object such a greater height than the other compartment is given to
it as may be necessary to secure proper draught. The chimney can also
of course be placed beyond the second compartment. Ordinary kilns of
the inverted cone pattern may be made available for the process by
dividing them with a partition wall as shown at b, Fig. 10; the first
compartment shewn at the left hand of Fig. 10 (and in which the fuel
is wholly or mainly introduced along with the mineral) is kept closed
at top by the lid d, excepting during the loading and whilst the excess
of moisture from the mineral is being driven off. The second or right
hand compartment is gathered up into a chimney as shewn.
partition b extends only part way down or is perforated at bottom so as
to allow the volatile products of the fuel from the first compartment to
pass over into the second. The system of a horizontal series of calcining
chambers is here reduced to its minimum, but still possesses the advantage
of making the volatile products of the coal (which in the ordinary
system of tunnel burning are all lost) subservient to the process.
Inlet holes 5, 5, are made in order to introduce the atmospheric air
which is necessary for the complete combustion both of the volatile
and fixed portions of the fuel. In the preparation of Scott's cement
the arrangement of chambers being as already described (as shewn
in Figures 7 and 9) sulphur, or sulphur ores, or other substances capable
of yielding sulphurous acid by ignition with access of air are consumed
or roasted at the bottom of the cooling chambers, and by suitable
passages 6, 6, the sulphurous acid thus obtained passes in amongst the
lime after it has been calcined, and acts upon it so as to convert it into
Scott's cement in the well-known manner. The calcined substance then
only requires to be ground to a powder to be fit for the market.
The
chambers can also be arranged in series around a central chimney
with which they can be put into communication or not as may be
required by means of dampers. And in all cases steam may be used
in the well-known manner in order to increase the flare at the expence
of glow fire in the fire-places.

page_text: Having now described my Invention, and the best means of carrying
the same into effect, I wish it to be understood that I claim,―
First. The combination and arrangement herein-before described of
compartments, chambers, and flues, and the mode of operating the
same in the calcination of minerals.
Second. For the adaptation of the above described kilns to the pro-
duction of Scott's cement as herein set forth.
In witness whereof, I, the said Henry Young Darracott Scott, have
hereunto set my hand and seal, the Thirtieth day of September,
in the year of our Lord One thousand eight hundred and sixty-
nine.
HENRY Y. D. SCOTT. (L.s.)