IMPROVEMENTS IN KILNS FOR DRYING AND BURNING BRICKS, TILES, TERRA COTTA, SANITARY PIPES, AND OTHER POTTERY WARE, LIME AND CEMENT, AND FOR SALT GLAZING
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by Gilbert Tucker and George Hodson
at the Office of the Commissioners of Patents on the 7th February 1876.
GILBERT TUCKER, of Loughborough, in the County of Leicester, Brickmaker, and
GEORGE HODSON, of the said Loughborough, Civil Engineer. "IMPROVEMENTS IN
KILNS FOR DRYING AND BURNING BRICKS, TILES, TERRA COTTA, SANITARY PIPES,
AND OTHER POTTERY WARE, LIME AND CEMENT, AND FOR SALT GLAZING."
This Invention relates to improvements in down draught kilns or ovens, and the
ordinary form of continuous action kilns when laid out either in a straight line or
in a circular or oblong form for drying and burning bricks, tiles, terra cotta, sanitary
pipes, salt glazed and pottery ware, and for burning lime or cement; and consists
in arranging the flues and dampers so that the waste heat and products of com-
bustion are utilized by being passed from kiln to kiln or chamber to chamber,
either in an upward or downward direction, or into alternate kilns or chambers,
according as the condition of the goods or ware in any of the chambers may render
desirable, allowing only so much heat to escape to the chimney as may be necessary
to secure the proper draught of the fires.
The flues are also so arranged as to render each kiln or chamber independent of
its fellows, so that when the fluctuations of trade, accidents, or repairs require it
they can be burnt off as separate kilns.
Another feature of our Invention is that the system of firing can be reversed
from an up draught to a down draught, and vice versa, at pleasure, so that green
goods can be dried off from the bottom, and the steam made to ascend through the
goods, thus avoiding the serious loss of time and risk involved in the old dome
draught kiln where much loss is occasionally caused by the steam from the green
goods softening the bottom rows and causing the kiln to reel. To effect these
objects each kiln or oven of the series, or each chamber when the system is applied
to continuous chambers is provided with a continuous flue passing under each oven
or chamber, as the case may be, and having a connection to the chimney between
each pair of ovens, or between each chamber when applied to the continuous
chamber system, with dampers so arranged as to either send the current of heated
gases from kiln to kiln or chamber to chamber, or into the main chimney.

page_text: In addition to this main continuous flue we also provide vertical nues constructed
within the outer walls of such kiln or oven, or within the division walls of such
chamber, which vertical flues are connected at the top of the kiln or oven with a
circular flue running round the dome thereof with suitable openings through the
dome which act in two ways, viz., either for the admission of heat from the kiln
last fired, or at which the firing is still going on, or for the extraction of the steam
from the kiln or oven if the contents are not sufficiently dried and hardenend as to
be in proper condition for the downward firing. When the system is applied to a
continuous chamber kiln, these flues are carried along the top of the arch, and have
openings through the arch into the chambers.
Both the vertical flues and the top flues are provided with dampers, by which the
various draughts both upwards and downwards are under control.
The firing holes for the kilns or ovens and for the continuous chamber system
are in the external walls, and are fitted with fire-bars, dead plates, and closely
fitting doors, so that draughts of cold air into the kiln or chamber are prevented,
and in addition to these direct firing holes we provide between each firing hole
intermediate firing, or as we term thein drying off holes communicating between
the false bottom of the kiln or chamber, the object of such drying off holes being
twofold, viz.,
1st. To dry off the goods previous to the burning process when from any cause
the heat from the other kilns or chambers of the series is not available for the
purpose as at the laying down of a new plant, or when the production has to be
curtailed.
And, 2nd. For the more equal diffusion of the heat of the kiln either when the
draught is upward or downward.
In working these kilns or continuous chambers when that system is adopted, we
commence with, for example, No. 1 kiln, which may be any kiln or chamber of the
series, by lighting the fires in the drying-off holes, and allowing the heat to pass
upwards through the goods into the upper annular flue in the case of ovens, or into
the top flues in the case of the continuous chamber system, from whence it passes
downwards through the downward vertical flue and direct to the chimney. When
the steam has been driven off from the goods and the bottom rows thoroughly
hardened and partially burnt, the drying off holes are stopped up and the fires are
lighted on the fire-bars, and the dampers arranged for the downward process of
burning, and the heat passed into the bottom of the No. 2 kiln, where it again
ascends through the goods and passes out through the apertures in the dome in the
case of an oven, or through the apertures in the arch when applied to the con-
tinuous chamber system and into the downward vertical flue, and thence either to
the chimney or to No. 3 kiln when it again ascends through the goods, repeating
this process throughout the whole series as far as the goods are set and ready for
burning.
The kiln or chamber is now fired until the burning of the goods is completed, by
which time it will be found that the goods in No. 2 kiln or chamber are red hot
and probably half burnt, the fires are then lighted on the fire-bars of No. 2 kiln or
chamber, and the draught of that kiln reversed, and the burning completed in the
ordinary way, the waste heat from No. 1 kiln or chamber being now brought
into No. 2 kilu or chamber by means of the upward vertical fiue, and distributed
through the apertures in the dome or arch to aid the burning of No. 2 kiln so long
as the temperature is sufficiently high for that purpose. When the temperature in
No. 2 kiln has been raised by the direct firing from the bars to a higher pitch than
the heat coming from No. 1 kiln or chamber, the upward vertical flue dampers are
'closed and the continuous flue dampers opened, and the waste heat from No. 1 kilu
which is now in process of cooling is passed beneath the No. 2 kiln or chamber,
and forward to No. 3 kiln or chamber, where it is made to pass either up the
vertical flue and through the apertures of the dome or arch, and down through the
goods, or upwards from the bottom of the kiln through the goods and into the

page_text: downward vertical flue, according to the condition of No. 3 kiln and the judgment
of the burner; in this manner the kilns or chambers can be rapidly burnt off and
cooled, so that one kiln may be drawn every day, or the process can be so delayed
that if circumstances require it not more than one kiln need be drawn every third
day.