IMPROVEMENTS IN KILNS OR OVENS FOR BURNING BRICKS, LIME, CEMENT, POTTERY WARE, BONES, ANIMAL CHARCOAL, AND THE LIKE, AND FOR BAKING BREAD, BISCUITS, AND OTHER SUBSTANCES
Year: 1871

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn
Fields, in the County of Middlesex, Gentleman, for the Invention
of "IMPROVEMENTS IN KILNS OR OVENS FOR BURNING BRICKS, LIME, CEMENT,
POTTERY WARE, BONES, ANIMAL CHARCOAL, AND THE LIKE, AND FOR BAKING
BREAD, BISCUITS, AND OTHER SUBSTANCES."-A communication from
abroad by Charles Eugène Emile Muller, of Paris, in the Republic
of France.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition,
on the 6th December 1871.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
of Middlesex, Gentleman, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN KILNS OR OVENS FOR BURNING BRICKS, LIME,
CEMENT, POTTERY WARE, BONES, ANIMAL CHARCOAL, AND THE LIKE, AND FOR
BAKING BREAD, BISCUITS, AND OTHER SUBSTANCES," a communication to me

page_text: 'from abroad by Charles Eugène Emile Muller, of Paris, in the Republic
of France, to be as follows:—
This Invention relates to a peculiar construction and arrangement of
kiln or oven for burning or baking various substances, and consists
essentially in the construction of a number of firing or baking chambers
separated from each other by perforated sides and bottoms, and disposed
either horizontally, vertically, or obliquely across the path of the flame.
Through these chambers the articles or substances to be burned or
baked, whether exposed or enclosed in muffles or cases, are caused to
pass along in a continuous manner by pushers or pistons worked by
levers, hydraulic cylinders, or other mechanical means so as to be
gradually brought towards and into the hottest part of the chambers,
and then by passing onwards to be as gradually conducted to the cooler
end of the said chambers; a small surface only of the bulk of the articles
or substances so traversed through the chambers being exposed to the
action of the flame, the process being thus progressive and continuous.
The said chambers are heated by gas generated in a gas generating
furnace, the flames of which play freely through the perforations in the
chambers, and after passing transversely through or across the said
chambers enter a heat regenerator of any well-known construction,
which serves to heat the air for supporting the combustion of the
gases.
The length of the chambers, and the speed at which the articles or
substances are caused to traverse through them will depend of course on
the nature of the substances under treatment.
Kilns or ovens constructed and worked on the principle above set
forth may be employed for the burning of ceramic goods of all kinds,
bricks, tiles, pottery, porcelain and enamelled ware, lime, cement,
plaster; also for the calcination of bones, the reburning of animal
charcoal, the carbonising of wood and peat, and the baking of bread and
biscuits.
In some cases the kiln may be heated by a furnace similar to a
metallurgical furnace built at one end, and the otherwise waste heat
after traversing across the heating chambers may be utilized for the
generation of steam or otherwise. Or any of the well-known systems of
generating heat may be applied to the improved kiln or oven.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Seal Patent
Office on the 6th June 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixth day of December, in the
year of our Lord One thousand eight hundred and seventy-one,
in the 35th year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said John Henry Johnson,
Her special license that I, the said John Henry Johnson, my
executors, administrators, and assigns, or such others as I, the said
John Henry Johnson, my executors, administrators, or assigns, should
at any time agree with, and no others, from time to time and at
all times thercafter 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 KILNS OR OVENS FOR
BURNING BRICKS, LIME, CEMENT, POTTERY WARES, BONES, ANIMAL CHARCOAL,
AND THE LIKE, AND FOR BAKING BREAD, BISCUITS, AND OTHER SUBSTANCES,” a
communication to me from abroad by Charles Eugene Emile Muller,
of Paris, in the Republic of France, upon the condition (amongst others)
that I, the said John Henry Johnson, my executors or administrators,
by an instrument in writing under my hand and seal, 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 John Henry Johnson, do hereby
declare the nature of the 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 accom-

page_text: to say :-
The said Invention relates to a new system of kiln or oven for the
baking or burning of ceramic products of every description, bricks, tiles,
paving tiles, special products of every form for buildings and ornaments,
crockery ware, china, decorations, enamelling, cement, plaster, lime, and
other substances. The principles on which this kiln is constructed have
never hitherto been applied for that purpose.
In order to set forth the features of novelty and the advantages of
this system, I shall, before enunciating the principle on which it is
based, describe one arrangement of kiln, and in order to enable the
system to be more fully understood shall take its application to a given
product, say bricks and tiles, as an example, reference being had to the
several Figures on the accompanying Sheets of Drawings.
Sheet 1 shews a kiln of this description with a tubular heat rege-
nerator, and Sheet 2 shows the application to the same kiln of a
regenerator on Ponsard's system.
Figures 1 and 2 show a vertical hopper disposed at the front of the
kiln into this hopper the fuel is charged which by an arrangement
similar to that of all gas generators is converted into carbonic oxide.
The fuel may be supplied at long intervals, which is a considerable
advantage. The surface of the fire-grate is so calculated that a slow
draft is obtained, and the combustion of the fuel being slow ashes only
are formed instead of scoria; the attention required by the fire is thus
reduced to a minimum. The fire-grate is also so arranged as not to
admit of the ingress of air into the passage until it has traversed a great
thickness of fuel. Carbonic oxide therefore only passes into the conduit
marked with an arrow in the section. O are the openings for the outlet
of the carbonic oxide from this passage.
Figure 4 is a transverse section which shows the passage for the
carbonic oxide and the openings O through which it escapes.
At each
side of this passage there is another passage, which is shewn rectangular
in the Drawing, whence heated air passes (as herein-after described)
through oblique conduits a which correspond to the openings O; a
mixture of air and carbonic oxide is produced; the combustion is
continuous when once the kiln is in operation, and in order to start it

page_text: it
may be readily fired. The blue arrows shew the admission of air. The
space above serves for the expansion of the flame. 6 are the dampers
on each side for regulating the admission of air. The admission of the
carbonic oxide from the passage may also be regulated with facility by
means of a damper. A damper R¹ either vertical or horizontal could be
readily applied.
Figure 4 illustrates the operation of the kiln which I shall now proceed
to describe, omitting from consideration for the present the heating of the
air. The products to be baked or burned are disposed on small carriers
composed of refractory clay, which are in contact with each other, and
are propelled by any suitable apparatus a distance of three to four inches
at a time. As the products advance towards the centre of the kiln
(which is perforated at the centre of the passage, leaving at each side an
edge on which the carriers slide) they are prepared to be subjected to
the intense baking or heating produced by the flames which are formed
at O, a, and which traverse the kiln from the bottom to the top by
passing through the openings formed immediately above. The flames
then pass into the upper flue c which extends along the kiln, dampers d
(Figure 4) being provided for the purpose of regulating the egress of
the flames. Each vertical row of passages thus becomes an oven into
which the products to be baked or heated pass, and the flame of which
is regulated at will at both its admission and outlet. The time for
traversing the passage is varied according to the nature of the materials
to be baked. As soon as the zone of flames is traversed it is required
that the cooling should commence, which is only possible on the con-
dition of being able to carry off the caloric radiated from the burnt
products. This caloric is transmitted to the partitions and to the soles,
and in order to utilize the heat thus absorbed the latter portion of the.
partitions is made hollow, as shewn in Figure 3. The iron flooring
which carries the lower sole of the kiln admits of passing beneath in
order to attend to the dampers 6 (Figure 4) and of the air being conducted
to the heat regenerator as herein-after explained. The iron flooring is
so arranged as to admit of air readily passing into the partitions. The
perforated soles also cause a draft, which in conjunction with the
absorption by means of the current of air in the partitions of the
caloric radiated admits of the successive cooling of the burnt or baked
products.

page_text: I shall now proceed to describe the heat regenerator. At the end of
the upper passage which receives the flames proceeding from the ovens
the flames are separated into two and descend through vertical flues.
On arriving at the bottom of the kiln the flames circulate in two
passages at the side of those for the carbonic oxide. These passages
which are formed in two tiers in which the circulation is in the down-
ward direction but the tubes through which the air passes upwards. It
will be readily understood that any other system of hot air stove or heat
regenerators would answer the same purpose. The regenerator on
Siemens' or Ponsard's system may be applied to this kiln with the
greatest simplicity.
Figures 5 and 6, Sheet 2, shew in detail the application thereto of a
regenerator on Ponsards' system, but a different arrangement may also
be employed. The longitudinal passage under the kiln in lieu of
receiving only the carbonic oxide gas may receive directly the mixture
of gas and air, and thus become the direct source of the flames to be
distributed throughout the kiln.. It is simply necessary to form as
before in the vault of the passage apertures corresponding to those made
in the whole of the upper soles, dampers being provided for the purpose
of regulating the distribution. The extremity of this flue is closed; the
whole of the flames which circulate therein necessarily traverse the kiln
and pass to the upper flue.
In the arrangements herein-before described the products to be baked
or burnt traverse horizontally a sheet of flames passing upwards; they
are carried by small carriers, which slide along the soles which separate
the kiln into several tiers or stories. It is evident that the reverse
arrangement might be adopted, videlicet, a limited space extended
having a current of flames passing therein horizontally as in a rever-
beratory furnace, through which flames the products to be baked or burnt
are caused to pass either in an upward or downward direction. In this
case the preparing and cooling passages would be vertical in lieu of
being horizontal as in the preceding example. The articles or sub-
stances to be baked or heated may also be caused to traverse the flame
in an oblique direction, in which case their weight would be sufficient to
effect their motion. The products to be baked or heated may be caused
to traverse the kiln vertically either in a downward or upward direction
without any difficulty; they are placed on moveable tables which

page_text: remain under the kiln completely outside, so that they are not exposed
'to the action of the heat. After each limited stroke of the table or
tables in the vertical direction the products placed on the top in a
column are maintained by a horizontal slide in order to admit of the
table descending again and being charged, or of discharging a portion of
the products. The vertical traverse. possesses the advantage that it
forms an oven without a casing for each pile of materials, which renders
possible the baking or heating of certain products without corroding,
wearing, or deteriorating the casing, as is the case in all kilns. In
order better to estimate the value of this arrangement it will be suffi-
cient to assume its application to the baking of superburnt blocks
(Portland cement for example). The consequences of this system of
baking may be readily appreciated; small portions of the materials or
articles to be baked or heated are successively heated. The baking or
3 heating and the cooling are progressive and successive. The heated
materials or articles are introduced successively with the precautions
which their nature may require into a limited space maintained at
an elevated temperature.
The duration of the passage of the materials or articles through the
kiln will necessarily be varied according to their nature. The burning
will be effected more rapidly according as a more elevated temperature
is maintained in the kiln, it being understood that the heating chamber
is to be so arranged as to admit of the products being rapidly exposed to
a high temperature without their being liable to be injured.
There are other considerable advantages resulting from the use of this
system of progressive and continuous baking or heating which has nothing
in common with those hitherto tried, among which advantages I may
enumerate the following, videlicet, the dispensing with the operation of
arranging or adjusting the articles in the kiln with the difficulties and
mishaps with which it is frequently attended. The great facility with
which the progress of the baking may be watched, since the attendants
can constantly inspect every part of the kiln. The preventing all loss of
heat, as the kiln never cools, and moreover requires less attention and
maintenance than any other kiln, from the fact of its being constantly
3 maintained at a uniform temperature. It is possible to bake or heat to
a greater or less degree in the same kiln and with the same constant

page_text: temperature, and that with the greatest varieties of baking, simply by
causing the articles which traverse it to pass more or less rapidly through
it. Enamels or glazing may be treated in a kiln of this nature with
every facility, since it is possible to follow them by the eye separately and
withdraw them as soon as they are suitably fused. In this case, as also
in that of the baking of china and crockery ware, the passages form in
fact retorts around which the flames in the central portion circulate,
along which passages the products to be baked pass successively, being
carried on suitable supports.
When the passages do not serve as retorts it is evident that economy
is effected in the construction of the kilns of a manufacturing establish-
ment by the fact of the arrangement of the kiln, and the continuity of
the baking or burning, piece by piece, brick by brick, tile by tile, and so
on. Large close and covered spaces, which involve considerable expense,
are not necessary for preparing large charges to be introduced or adjusted
in the kiln. All that is required is to provide for the drying of the daily
production, since the kiln is capable of delivering each day that which
has been manufactured during the same day, by which considerable
economy may be effected in the cost of erecting works, and in capital
,and interest. In short, the kiln constructed on this system consists of a 2
powerful and never failing source of heat, which may be varied at will in
intensity, and even in its nature if desirable, from which source exactly
what is required to make a given product may be derived, such source
of heat being so disposed that there exists, either on the sides or above
and beneath, means for transmitting heat, which the special arrangement 2
of the kilns admits of being varied according to the nature of the
products to be baked or heated.

page_text: saving over that herein-before described the following may be men-
tioned; two of them are shewn in the Drawings:-The kiln may be
heated by the combustion of heavy oils or of gases produced in any gas
generator, or by the application of fires on Siemens', Ponsard's, Böctias',
and similar systems with a heat regenerator.
Another condition to be fulfilled in the baking or burning of certain
products, and which the gas generators on Siemens' and Ponsard's systems
meet better than other furnaces is the necessity for having some pressure
in the kiln for any delicate product which will not sustain a sudden
change of temperature. It will be readily understood that if the draft
of the chimney be such that this internal pressure cannot take place,
the air would enter through the passages for the materials to be baked
and interfere with the successive heating and cooling. It is more par-
ticularly when an arrangement of kiln is adopted in which the products
are traversed in the vertical direction, that the introduction of the
external air would impede the working of the apparatus, the horizontal
traverse offers less inconvenience. This may be remedied by certain
special arrangements, but in principle in the case of the products referred
to it is preferable to employ a heat generator which admits of maintaining
internally a pressure of the gas variable at will but constant.
'
It is necessary to observe that the application of the Siemens' system
to the baking or burning of ceramic products, especially china, has
already been proposed and tried, but in such trials the essential features
which constitute my said Invention were not applied, the ordinary
apparatus for utilizing heat being employed whilst changing the mode of
heating, whereas on the contrary I employ a peculiar kiln and mode of
heating which may be varied according to circumstances. This Inven-
tion therefore relates to the kiln, and to the combination with this
arrangement of kiln of any of the before-mentioned systems of heat
generators.
I have before stated that even the nature of the heat may be varied at
will. This fact, however, is not of importance for many manufacturers,
but it is one of the features which I intend to apply to the kiln con-

page_text: specially constructed with a view to carrying out of my improved
system of progressive and successive heating or baking, as herein-before
described.
In witness whereof, I, the said John Henry Johnson, have to this
my Specification' set my hand and seal, the Sixth day of June,
One thousand eight hundred and seventy-two.
J. HENRY JOHNSON. (L.S.)