Improved Methods of Firing Kilns for Burning Bricks and analogous Materials with Gaseous Fuel, and in Plant therefor.
Year: 1895

page_text: Date of Application, 12th Mar., 1895-Accepted, 7th Mar. 1896
COMPLETE SPECIFICATION.
Improved Methods of Firing Kilns for Burning Bricks and analogous
Materials with Gaseous Fuel, and in Plant therefor.
We, BENJAMIN HOWARTH THWAITE of 95 Finsbury Pavement in the City
of London, Civil Engineer and WILLIAM JOHNSON of Castleton Foundry
Armley near Leeds, Mechanical Engineer do hereby declare the nature of this
invention and 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 an improved method of firing kilns for burning bricks
and analogous materials with gaseous fuel, by which not only is economy of fuel
secured, but the bricks are burnt more uniformly and more thoroughly.
The character of our invention will be best understood by reference to the two
figures shewn on the accompanying drawings, Sheet 1 and Sheet 2.
Figure 1 represents a vertical section of the kiln, half of which section is taken
through line A to A, the other half being taken through B to B, marked on
Figure 2, which represents a plan in section of the kiln, half of which is taken on
line C to C and half on line D to D marked on Figure 1.
The chambers in which the goods are placed to be burnt are marked E 1, E 2,
E 3, and E4, on one side of the kiln, and F 1, F 2, F 3, and F 4, on the other side.
The division between the two groups of kiln chambers being effected by the
central wall G, and the longitudinal and main flue H. The gas generator chambers
in which the gaseous fuel is generated are constructed so as to form the two end
walls of the kiln, these generator chambers are marked J 1, J 2, and K 1, K 2. In
the example shewn by the Figures 1 & 2, two gas generating chambers are provided
at each end of the kiln, having a central gas take-off and downcomer flue L, by
which the gas from the gas generater chambers enters at each end of the longitudinal
gas flue H.
The gas from the gas flue H, can flow into the several brick-burning cham-
bers, E1, E2, E3, E 4, F 1, F 2, F3, and F 4, when the regulating mushroom
valves N 1, N 2, N 3, N 4, and N 5, are opened.
The gas is however preferably only turned into one or two chambers at the same
time. The gas valves N 1, N 2, N 3, N 4, and N 5, are regulated by the spindles O,
that terminate in wheel standards P, formed at the top of the kilns.
The regulating mushroom valves sit on a valve plate Q resting on the circular
outlets R, built in arch formed over main gas flue H.
The gas flows into the transverse flues S, that in a way separate the brick burning
chambers or compartments from each other.
gas
The transverse flues S, bave well distributed orifices T, by which the is made
to flow evenly into the brick burning chambers.
The transverse gas flues S, act also as chimney flues, in a manner to be herein-
after described, and when acting as such, the chimney dranght is regulated by
vertically acting valves U.
The procedure when burning is as follows:-
is
Assuming all the chambers to be filled with the goods to be burnt, the gas
turned into one of the transverse flues, say for example the one in the kiln chamber
marked F 3, at the same time that its corresponding gas valve is opened, all the
chimney valves except the one marked U¹, which is either the fourth or sixth
removed from the chamber in which the gas is ignited, are closed, the result of
this arrangement of actuating the valves, is as follows the flame from the kiln
.
.

page_text: chamber F 3, flows through the whole of the goods filled chambers, until it reaches
the chamber the fourth or sixth removed, as the case may be, and of which the
chimney valve or damper is open. From this last chamber the residual gases
escape by the curved flues V, into the chimney flue X.
Chimney flues X are provided on each side of the kiln as shewn in Figure 2.
Now the goods in the chamber where the gas is ignited are the first to be burnt to
the full extent and after they are completely burnt the gas is turned off from its
transverse flue, and turned on into the next and following chamber which has
already become highly heated with the flame produced in the first chamber in
which the gas was ignited. In order to cool down the fully burnt bricks rapidly
and in a manner that will enable the heated store in the bricks to be fully recovered
air is allowed to enter in the well distributed openings in the roof over the chambers
and marked Y, as well as into the flue that forms the gas flue, by valve openings Z
formed in the outside wall opposite the gas flue, mushroom air valves already
referred to, are provided to control this supply of air.
The air flowing through the newly burnt stack of goods becomes highly heated
before it reaches the line of gas inlet passages.
It will therefore be realised that practically there is no heat lost.
After the second chamber contents have been fully burnt the gas is turned off
from its feeding transverse flue and turned into the next and immediately following
chamber. On each change of the gas valve there is a corresponding change in the
chimney flue valves or dampers in such a way to compel the flame and heated gases
to flow through the full and desired complement of brick filled chambers.
We may provide a secondary distributing gas flue 2 with transverse gas flues 3,
built on the top of the kiln, by which a secondary and distributed supply of gas is
supplied to the centre of the brick burning compartments.
Figures 3, 4, 5, and 6, on Sheet 2, of drawings, represent an alternate and
preferable arrangement of our invention.
Figure 3, is a longitudinal section taken half through the central gas conduit on
line FF of Figure 4 and half through the brick burning chambers and gas
producer on line E E of Figure 4.
Figure 4, is a plan of kiln, half in section through line A, B, partly in section
through gas distributing and initial combustion flues, the remainder of plan
shewing the top of gas generator and the method by which the gas and air valves
are simultaneously opened.
•
Figures 5 and 6, are details shewing the construction of the brick kilu floors.
Figure 5, being a vertical section and Figure 6 a plan of the floor of perforated
tiles.
In this arrangement the flue gas flows to the different parts of the kiln as before.
The gas is also led by distributing cross flues 2, from the central gas conduit 3 as
before, but instead of the combustible gas ascending through perforations in the
arch of the distributing gas flue into the brick burning chambers; it is partially
supplied with air; and in a state of incomplete or primary combustion, the
partially inflamed gases flow into the under floor chamber 4, of the kiln. To
effect this partial combustion, we provide air flues 5, beneath each of the gas
flues 2, the air entering into the upper gas flue by and through well distributed
openings in the roof of the said air flue.
The regulation of the air flow is effected by means of an external mushroom or
sliding valve 6.
A chain Y, attached to an air valve passes to the upper part of
the kiln and to the corresponding gas valve standard 8. By this chain, the action
of the lifting of the gas valve serves to lift the corresponding air valve. The
inflamed gas under the floor of the kiln enters such kiln through well distributed
perforations 9, so that an equal distribution of heat is provided over the entire area
of the kiln floor.
The secondary supply of air to effect the complete combustion of the gas jets,
already in a partial state of combustion, is supplied by the air flowing through the
bricks that are being cooled down, so that such air is highly heated and as it meets

page_text: the gas jets in a partial state of combustion, the flame is completely supplied with
heated air, and combustion, of a rather intense character, is the consequence.
The under floor chambers, beneath the kiln floor, are covered with perforated
rebated tiles 10 (see Figures 5 and 6) each tile having one or more perforations 9, of
such a form and of such a number as to permit the establishment of a jet of flame
spread over the entire floor area of the kiln.
These perforated and rebated tiles 10 are supported by checker brick walls 12,.
that allow the gases in a partial state of combustion to flow freely under the floor
of the kiln. The chimney connections 13, are arranged in the centre of the kiln,
the chimney draught is regulated by means of a mushroom shaped valve 14, or by
means of a vertical sliding valve as may be found most convenient.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same may be performed, we declare that what we
claim is included in the following statement:-
First. The method of constructing as part of the kiln structure, one or more
gas-generators in the two end walls of each kiln, substantially as shewn and
described.
Second. The method of distributing the gaseous fuel to the different chambers
or divisions of the kiln by means of a central flue.
Third. The valvular arrangement for regulating the gas distribution.
Fourth. The chimney flue connections to the various portions of the kilns.
Fifth. The general disposition of both the gas and chimney flues, and the
arrangement of chimney valves.
Sixth. The method of introducing the gas by distributing flues, on the top of
the kiln.
Seventh. The method of obtaining equal diffusion of heat through the kiln
chambers.
Eighth. The sequential method of heating the bricks and utilising the cooling
of the burnt bricks for adding to the heat of combustion in combination with our
invention.
Ninth. The gas fired brick kiln substantially as herein shewn and described.
Tenth. The method of forming the gas orifices over the gas distributing flue,
substantially as shewn and described.
Eleventh. The method of establishing a uniform combustion of gas over a
rectangular or other form of floor for the burning of earthenware, pottery or brick
goods.
Twelfth. The general arrangement of gas and air flues as shewn on Figures 3
and 4, substantially as shewn and for the purpose described.
Thirteenth. The arrangement of gas air and chimney valves, substantially as
shewn and for the purpose described.
Fourteenth. The perforated flooring tiles and method of constructing such floor
as shewn in Figures 5 and 6, substantially and for the purpose described.
Dated this Eleventh day of March 1895.
B. H. THWAITE.
WILLIAM JOHNSON.