Improvements in the Construction of Muffled and Semi-muffled Kilns for Burning Biscuit and Glazed Ware.
Year: 1896

page_text: Date of Application, 14th Nov., 1896
1007
PROVISIONAL SPECIFICATION.
Improvements in the Construction of Muffled and Semi-muffled Kilns
for Burning Biscuit and Glazed Ware.
We, J. DUCKETT AND SON LIMITED, of Sanitary Ware Works, Burnley, in the
County of Lancaster, JAMES DUCKETT of Woodleigh, Burnley aforesaid, Sanitary
Ware Manufacturer, and JOIN WHITAKER BULLOCK of 36, Accrington Road,
Burnley aforesaid, Manager, do hereby declare the nature of this invention to
be as follows:-
Our invention relates to improvements in the construction of muffled and semi-
muffled kilns for burning biscuit and glazed ware, and applies particularly to
kilns with two concentric arches or domes with an intervening space.
Instead of constructing the inner arch or dome of ordinarily sized radiated
solid fire bricks as heretofore, we construct it of large deeply panelled fire-clay
blocks, which we prefer to average about eighteen inches square on the soffitt,
four to seven inches at the beds and joints, and one or two inches thick in the
panels, the dimensions varying with the size and form of the kiln, and the
span of the arch or dome, the panels being at the soffitt of the arch or dome.
The blocks may, however, be of any desired dimensions, the larger the kilns,
the larger the blocks, and vice versa. The panelled blocks may also be used in
the construction of inner walls and floors of kilns.
It is manifest that this mode of constructing domes, arches, walls and floors
of kilns is sound and thoroughly practicable, and that the heat from the furnace
will pass much more readily through these panels, than as heretofore through a
solid dome, arch, wall or floor, of uniform thickness.
Muffled kilns have hitherto been built rectangular in plan, and in order to
secure sufficient firmness (the span of the inner arch is only about seven feet),
and the kiln is fired on one side only, which we call the front of the kiln. The
inner lining of the back wall of such kilns, is built so as to leave about three
inches space or cavity between it and the back wall, which space answers as a
flue to convey the heated gases or products of combustion between the inside
lining and the back wall of such kilns, thence under the floor, into the main
flue, and forward to the chimney.
The lining of these rectangular kilns as well as the arch may be built of
large panelled blocks of any reasonable dimensions.
The floors of these kilns may likewise be constructed of panelled blocks sup-
ported at each corner by pillars, or they may rest on the walls of the flues, where
there are no pillars.
We prefer both muffled and semi-muffled kilns round or circular in plan, and
constructed on what is known as the "Down Draught Principle," and with a
vertical flue in the centre.
For circular muffled kilns no opening or openings are formed either in the floor
or in the central vertical flue, and the products of combustion pass from the
furnace as follows:-First upwards through the narrow space between the inner
and outer domes, then downward through the said vertical flue, and then through

page_text: the spaces immediately under the thin floor of the kiln, circulating amongst and
between the pillars, which support the floor, which is formed of panelled or
other suitable thin tiles which are preferably supported at each corner by the
said pillars.
Immediately under the floor upon which the said pillars rest, we form say six
or any suitable number of flues, the internal section and dimensions of each of
which may be about fifteen inches square, but the size and number will vary
according to the size of the kiln. These flues all radiate from the outside, and
converge towards the centre of the kiln, where the products of combustion meet
and descend vertically into the main flue leading to the chimney.
At the outside end of each of the said six flues and in the cover thereof, we form an
opening, say about fifteen inches by ten inches, at the centre of the kiln we
form another small opening, and between the two said openings, we form two
more openings, the one being about fifteen inches by four inches, and the
other about fifteen by three inches, all of which are about uniform distances
apart.
Down these openings the products of combustion descend into each of the
said six flues, and pass forward to the main flue in the centre as before mentioned.
For semi-muffled kilns the said vertical central flue and the floor are perforated,
so that the products of combustion may pass freely through them, when on their
way to the chimney.
Near the bottom of the said vertical central flue and at about floor level we
fix a damper, by opening which during slow firing, a large percentage of the
steam, dust, et cetera, will pass out of the kiln without going through the chamber,
and injuring the goods therein. During full firing, this damper is closed so as
to cause the whole of the heat to pass through and under the kiln on its way to the
chimney.
A damper is placed in the main flue outside the kiln to regulate the draught.
In order to obtain still more heat in the chamber, one or more openings may
be made in any or all of the aforesaid panels in the dome or arch. These
openings may be covered with any suitable very thin fire resisting material. The
heat will then readily pass through these very thin parts of the dome or arch,
and the openings. will form convenient hand holes for removing dirt or droppings
from the top of outer arch or dome, when the said thin fire resisting cover is
temporarily removed.
In a modification of our invention, we construct domes, inner arches, and walls
of kilns of thin slabs of fire clay, on the underside of which we form a series of
narrow ribs, but we prefer the former plan as it secures comparatively broad beds
and joints. Or both ribs and panels may be dispensed with, and parallel blocks
may be used, each block having a lot of holes sunk into, but not quite through
it.
Improvements in the Construction of Muffled and Semi-muffled Kilns
for Burning Biscuit and Glazed Ware.
We, J. DUCKETT AND SON LIMITED, of Mitre Sanitary Works, Burnley, in the
County of Lancaster, JAMES DUCKETT of Woodleigh, Burnley aforesaid, Sanitary
Ware Manufacturers, and JOHN WINTAKER BULLOCK of 36 Accrington Road,
Burnley aforesaid, Manager, do hereby declare the nature of this invention, and

page_text: in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
Our invention relates to improvements in the construction of muffled and semi-
muffled kilns for burning biscuit and glazed ware.
We construct the inner dome of largely panelled fireclay blocks, which we
prefer to average about eighteen inches square on the soffitt, and about six inches
at the beds and joints, and one to two inches thick in the panels; these dimensions
may be varied if desired.
Our invention is for muffled or semi-muffled kilns circular in plan, and con-
structed on what is known as the down draught principle, and with a vertical
flue at or near the centre.
For circular muffled kilns, no opening or openings into the interior of the kiln
are formed either in the floor, or in the central vertical flue, and the products of
combustion pass from the furnace as follows: First upwards through a narrow
space formed between the inner and outer domes, then downward through the
said vertical flue, and then through the spaces immediately under the thin floor
of the kiln, circulating amongst and between the pillars which support the
floor.
For semi-muffled kilns the said vertical central flue and the floor are perforated,
so that the products of combustion may pass freely through them when on their
way to the chimney.
In order to obtain still more heat in the chamber, one or more openings may
be made in any or all of the aforesaid panels. These openings may be covered
with any suitable very thin fire-resisting material. The heat will then readily
pass through the very thin parts of the dome, and the openings will form con-
venient hand holes for removing dirt from the outside of inner dome, when the
thin fire-resisting cover is temporarily removed.
In a modification of our invention, we construct inner domes with parallel
blocks having holes sunk into but not quite through the blocks.
For the purpose of making our invention clear, we annex drawings:-
Fig. 1 is section of muffled kilu, Fig. 2 section of panelled block with loosa
stopper, Fig. 3. plan underside of same, Fig. 4. section of semi-muffled kiln,
Fig. 5. section of ordinary panelled block, Fig. 6. plan underside of same.
A is the furnace, B space between domes, C vertical fluc, D.D interior of
kiln, E panelled block, F loose stopper to same, H H holes in vertical flue.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is:-
The use of down draught muffled or semi-muffled circular kilns, with inner dome
constructed of deeply panelled blocks made of fireclay or other suitable fire-
resisting material, in the manner, and for the purpose substantially as described.
Dated this 12th day of August 1897.
F. RICHMOND,
12, Standish Street, Burnley, Agent for the Applicants.