IMPROVEMENTS IN THE CONSTRUCTION OF KILNS FOR BURNING BRICKS AND OTHER GOODS
Year: 1875

page_text: LETTERS PATENT to William Bull, of Portswood, in the County of
'
Hampshire, Civil Engineer, for the Invention of " IMPROVEMENTS
IN THE CONSTRUCTION OF KILNS FOR BURNING BRICKS AND OTHER GOODS."
Scaled the 20th July 1875, and dated the 31st May 1875.
COMPLETE SPECIFICATION filed by the said William Bull at the Office
'
of the Commissioners of Patents, with his Petition and Declaration,
on the 31st May 1875, pursuant to the 9th Section of the Patent
Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
BULL, of Portswood, in the County of Hampshire, Civil Engineer, send.
greeting,
WHEREAS I am in possession of an Invention for "IMPROVEMENTS
IN THE CONSTRUCTION OF KILNS FOR BURNING BRICKS AND OTHER GOODS," and
have petitioned Her Majesty to grant unto me, my executors, admini-
strators, and assigns, Her Royal Letters Patent for the same, and

page_text: the cross chamber; p, p, cross chamber; ", ", narrow longitudinal flucs
on floor of kiln; 8, 8, coal pockets over flues j, j.
I now proceed to describe the peculiar and novel features of, and the
methods to be used preferably in working the improved kiln.
The said kiln is represented by a structure or an excavation, as the
case may be, with parallel vertical sides of any convenient width or
length, but with a sloping floor or bottom at an inclination of one in
seven and a half (more or less) to the horizon. It may be found of
advantage to arch it over in order to avoid the necessity of covering it
with earth or ashes and fixing the pipes for the feed holes as hereafter
described every time tho kiln is fired. If, however, the kiln bo open at
the top the bricks must be covered with four inches, more or less, of
carth, ashes, or rubbish, in which the pipes or feed holes k, k, through
which the fuel is fed are set. If it be arched over, corresponding feed
holes must be left as required. At the lower end of the kiln a low wall
is to be built, with openings n (Figs. 1, 2, 4) for firing, similar to thoso
of an ordinary flame kiln. For a length of four feet, more or less, insido
these openings, and running in the direction of the length of the kiln,
rows of fire-bars i (Figs. 1 and 2) are to be set, made of any suitablo
material, with an ash-pit m (Figs. 1 and 4) below each row. Theso
openings n, n, should be about 2 feet apart from centre to centre. Over
the fire-bars flues j, j, should be set of unburnt bricks to form a series
of combustion chambers for getting up a sufficient heat in the bricks
beyond to enable the firing from the top to commence, as it is by the
latter that the bricks or other goods are really burnt, the firing below
being merely a preparatory arrangement. The kiln, as before stated,
may be simply an excavation, open or arched over, as the case may be,
where ground with the proper slope is available. On level ground it
may be partly excavated and partly built, or it may be entirely built and
the interior floor raised or dressed to the proper inclination. In any case
it may be roofed over on any convenient plan.
The "setting "of the bricks which has been found to give the best
result is shown by the plans and sections in the Drawing, but other
methods of setting may be found applicable to this form of kiln. Tho
bricks in the courses a, a, and b, b, between the coal-receiving courses
0.9, are set one inch (more or less) apart, and it is through the spaces

page_text: so left and the small flues p, p, that the smoke, heat, and waste products
of combustion are carried forward.
The firing is carried on as follows:-For a length of time, which will
vary according to circumstances, but generally will be about 36 hours,
firing is continued in the flues j, j, below with coal, wood, or any other
suitable fuel, until the whole section of the load up to the first cross
chamber p, p, shall be red hot. This being the case each pipe in the
first line of feed holes k, k, is to be fed with six ladles of small coal,
each ladle for a kiln of the height shown in the Drawing containing
onc lb: (more or less) of coal, or an equivalent of other fucl, so that all
the bricks o, o, spanning the combustion chamber p, p, may receive each
a quantity or portion, the rest falling to the bottom of the cross chamber
on the floor of the kiln. Allowing this an hour to be well burnt regular
feeding of one ladleful of coal every succeeding quarter of an hour
should be carried on.
About three hours after the first line or row has
been started a second and following line or row may be commenced in
precisely the same way, and so on until six lines or rows are working,
which in practice has been found sufficient. No more feed holes k, k,
should be opened until by the settlement of the goods there is reason to
believe that those in front of the line of feed holes first fired are
sufficiently burnt or baked when the feed holes in it should be finally
closed by a dab of clay, and another line of feed holes fired as before,
and so on throughout the entire length of the kiln. For covering the
feed holes k, k, light cast-iron cups, plugs, caps, or lids 1, 1, with a
recessed or sunk handle on the top for lifting them off are best, but well-
burnt carthenware caps will answer. The holes which are being fed are
of course only uncovered for the purpose of introducing the fuel, and six
or eight holes in front of the feeding should be kept covered over to keep
in the heat as much as possible. When starting the firing below all tho
feed holes above should be left open until the steam be completely driven
off, and after this has taken place each row should be closed as far as the
eighth row, by which time firing at the top will probably have com-
menced. In no case is it of advantage to close more than eight rows in
advance of the firing, and sometimes a lesser number may be closed to
increase the draught. On closing the first row or line of feed holes
finally tho firing into the flues j, j, below should be slackened down,
but if possible a gentle fire should be kept up until about six rows of

page_text: feed holes have been finally closed, and then be entirely stopped, the
flue apertures n, n, being left quite open to supply sufficient draught.
From the first there is a very strong draught which carries the heat
away from the bricks over the flues j, j; sufficient coal or other fuck
should therefore be put in the pockets 8, 8, (as shown in the Drawing)
to burn them. The waste heat from this also goes forward. All the
lower pockets in 9, 9, courses may with advantage also be filled with
coal, as shown in the Drawing.
As soon as the lower end becomes sufficiently cool the bricks should
be unloaded, and this should be done regularly and consecutively, so that
the draught may not have to pass through or permeate a greater length
in the rear than is necessary.
Two kilns constructed side by side will be found to work advan-
tageously, and may be roofed over on any desired plan.
Having thus described the nature of my Invention and the manner in
which the same is or may be carried into effect, I claim,---
1stly. The form of kiln. This being constructed on an inclined planc,
such a draught is caused as shall not only effect a thorough combustion
of the fuel fed first in the flues below and afterwards through the feed
holes above, but also carry off the waste heat through the unburnt
goods in front of the firing without the addition of any chimney with its
flues, dampers, and other complications; in other words, making the kiln
its own chimney.
2dly. The method or plan of wholly or partly excavating the ground
to form the kiln, thereby saving expensive brickwork or wall.
3dly. The adaptation of the principle of firing from the top to a form
of, kiln in which the power to induce a sufficient draught, to utilize the
heat from the bricks already burnt, to effect a thorough combustion of
the fuel, and gently to force the waste heat and other products of
combustion through the unburnt bricks is inherent in itself.
4thly. The method of starting the firing by treating the lower end as
an ordinary flame kiln with flues and fire-bars, and after a sufficient
length is heated utilizing the waste heat by taking the draught through
this length.
5thly. The method of setting the bricks and form of combustion or
cross chambers p, p, described, which extending as they do the whole

page_text: width and height of the kiln, give a perfect diffusion of heat over the
entire section.
6thly. The process or combination resulting from the whole of the
above features taken together, or any parts taken by themselves.
In witness whereof, I, the said William Bull, have hereunto set my 5