Year: 1873

page_text: emptied in succession. By constructing and arranging the kiln in this
manner the burning operation is always being carried on in one or other
of the compartments while others are cooling so as to be ready to have
their contents removed and fresh articles introduced. It has however
been found that in such circular kilns there is great difficulty in causing
the heat to diffuse itself uniformaly through the goods in the kiln or
rather in the separate compartments thereof, and as there is always
a tendency for the heated gases and air to take the shortest cut to the
chimney there is a liability that some of the goods will be overburnt
while others in the same compartment will not be burned enough. I
obviate this difficulty by constructing my kiln in the form of one long
straight chamber or tunnel with an arched roof. Firing holes are
placed at one end of this tunnel and exit flues at the other. In one of
the side walls (at regular distances apart) are other firing holes and also
openings to obtain admission to the tunnel or long chamber at different
part. In the other walls are constructed (also at regular distances
apart exit flues which are provided with dampers so that the draught
may be regulated or altogether cut off when required. In the arched
roof of the tunnel are made a number of holes for the purpose of
allowing steam to escape from the green goods while they are being
dried. These holes are provided with stoppers so that they may be
closed while the burning operation is being carried on.
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My improved kiln may be made of any length, but it will be found
most convenient in working not to make it more than 100 feet long, and
to have a lateral firing hole and corresponding flues on the opposite side
at about every 20 feet besides the firing holes and exit flues at each
end. It will be found convenient in practice and economical in
construction to arrange these kilns in pairs, side by side, so that the
central wall (between the two tunnels) will serve to receive the flues of
both kilns. The two tunnels should also be made to communicate
at both ends by means of lateral passages which however may be
temporarily closed when required.
The operation of the kiln is as follows:-The beginning or one end
of the tunnel (to the length of say 20 feet) is filled with goods and is
temporarily closed in at back by means of a sheet-iron, wooden, or other
partition made air-tight by daubing all the crevices with clay. Fires
should then be lighted in the end holes and the holes in the arched roof
opened to allow the steam to escape. When the goods are dry the firing

page_text: may be increased in order to burn the goods, and the gases may be
allowed to escape up the first lateral flue. In the meantime a second
20 feet length of the tunnel will have been charged with goods and
closed in behind by means of a partition. The first partition may then
be removed and the gases from the first 20 feet allowed to pass among
the goods in the second 20 feet and thereby dry them, the damper of
the lateral flue having been closed to prevent the heat and gases from
escaping in that direction. A third 20 feet of the tunnel is charged in
the same manner and supposing the goods in the first division to
have been sufficiently burned the fires connected with that part are
extinguished and air allowed to pass in and among the goods so as to
cool them down ready for removal. The hot air thus obtained passes to
the 2nd division and assists the combustion in that part.
The fires are ignited and kept up in the lateral fire-places as the
tunnel is gradually filled with goods, and when the divisions that were
first charged are sufficiently cool the goods may be removed therefrom
and a fresh charge introduced, and so on continuously. If the kilns are
arranged in pairs as above mentioned the lateral openings at each end may
be used to allow the heated gases from the one kiln to pass through
the goods in the other so as to utilize as much as possible of the heat.