Improvements in Continuous Kilns or Ovens with Travelling Hearths for Firing Ceramic Goods.
Year: 1898

page_text: Date of Application, 15th June, 1898
Complete Specification Left. 15th Mar., 1899-Accepted, 13th May, 1899
Date of Application, 15th June, 1898
Complete Specification Left. 15th Mar., 1899-Accepted, 13th May, 1899
Improvements in Continuous Kilns or Ovens with Travelling Hearths
for Firing Ceramic Goods.
I, CHARLES DENTON ABEL, of Birkbeck Bank Chambers, Southampton Build-
ings, Chancery Lane, in the County of London, Consulting Engineer and Chartered
Patent Agent, do hereby declare the nature of this invention (which has been
communicated to me from abroad by La Société Anonyme des Faienceries de
Creil et Montereau and Ernest Gabriel Faugeron, Engineer, both of Montereau,
Seine et Marne, France,) to be as follows:
The continuous kilns or ovens having travelling hearths which have been
proposed heretofore for firing ceramic goods do not sufficiently utilise the heat
of combustion of the fuel and are unsatisfactory both from the point of view
of the progressive and uniform heating and cooling necessary for ceramic goods
and from the point of view of the smooth conveyance of fragile articles, often
placed in a position of unstable equilibrium.
By this invention the first named desiderata are obtained by a special arrange-
ment of the arch and walls of the kiln and by refractory partitions which travel
with the goods to be fired, the general construction being such that the products
of combustion traverse successively and uniformly all the goods to be fired and
are followed in a similar way by the air necessary for cooling the said goods.
The last above named desideratum, namely smooth conveyance, is obtained by
rolling the waggons on continuous rails without stopping them. The rails are
preferably on a slight incline so that the waggons may travel in the kiln by
their own weight and need only be held back at the mouth of the kiln.
The kiln is a long, straight tunnel of which the arch is in places depressed
and the walls are traversed by flues, some of which. establish a communication
between the inside of the tunnel and the outside, others with the fire grates
and others with the chimney. The said fire grates are on each side of the tunnel
at about the middle of its length. The train of waggons travels through this
tunnel, say from left to right, each carrying a refractory partition at one end.
The form of these partitions is that of the reduced cross section of the tunnel
at its entrance and at the places where the arch is depressed, so that they act
as baffles at these places. The partitions may be constructed of one piece or of
separate pieces or may be constituted by the goods themselves or by saggers; in
the latter case the goods or saggers should rest directly on the waggon, not on
blocks. It is preferable to make the partitions of two pieces which can be
lightly supported against the piles of saggers.
The baffling function should be as perfect as possible at the entrance, so as
to hinder access of cold air and at the depression immediately to the right of
the fire grates, so as to divide the firing part of the furnace from the cooling
part. The entrance of the tunnel, being always cold, may be lined with plates

page_text: of sheet iron or of any other suitable material laid parallel with the interior
walls and sufficiently closing the space between the partitions and the walls. It
is desirable that the depression at this part of the furnace should be long enough
to allow several partitions to act as baffles, so as to diminish the chances of air
entering and reaching the chimney, which is at this end of the tunnel.
To form the depression which is immediately to the right of the fire grates
metal cannot be used on account of the high temperature. Here again the
depression is extended so as to multiply the number of partitions which act as
baffles for a purpose to be presently described. Otherwise the necessity for
complete baffling is not so necessary at this point as at the entrance, since the
small quantity of air which can pass, will do no harm because it will be heated
by contact with the fired goods.
The flames from the lateral fire grates enter the tunnel through ports on each
side placed at a level above the refractory platforms of the waggons. The saggers
or the goods are placed on blocks which are a little higher than the ports so
that the flames enter among the goods from beneath and travel upwards and
heat them. The products of combustion then pass over the partition to the
left, downwards among the goods on the next waggon, and out into a flue in
the wall of the furnace through ports opening thereinto at the level of the
waggon. They are drawn in this direction by the chimney draught; being pre-
vented from travelling along the arch of the tunnel by a depression which
of such a length that there is always a partition passing under it and thus forming
a baffle.
The flue in the wall conveys the products of combustion past the baffle-and
they then enter at the bottom of the next waggon through ports in the wall of
the tunnel. The same course is repeated, the gases gradually parting with their
heat to the goods or saggers, until the entrance is reached. Here the depression
of the tunnel which forms the baffles with the partitions is a plate which leaves
a passage between it and the arch of the tunnel; the gases pass along this passage
and down suitable flues in communication therewith and situated at the sides of
the tunnel, before they arrive at the chimney. Thus this portion of the tunnel
plays the part of a muffle through which the waggons pass as they enter the
furnace. For facilitating the transmission of the heat from the flues, the walls
are made of hollow bricks.
In that part of the tunnel where the waggons are most highly heated it is
necessary to provide plugged spy holes in the walls to permit of the course of
the firing being watched.
The cooling of the fired goods and the recovery of their heat are effected in
the following manner. Immediately to the right of the fire grates there is a
depression sufficiently long to form several baffles with the travelling partitions
and this portion of the tunnel has no communication with the flues in the walls,
so that it is in effect a closed chamber the contents of which can cool solely by
radiation and conduction, except in so far as circulation of air is possible owing
to the imperfection of the baffles. The cooling of the goods in the part of the
tunnel beyond the long depression occurs on exactly the same principle as that
underlying the heating of the goods described above. The end of the tunnel
has a depression which forms a baffle with the partition which happens to be
passing out. The air, drawn by the draught of the chimney, passes into flues
in the walls and thence through ports in the walls at the level of the waggons;
it then passes up through the goods becoming heated during its passage and cool-
ing the goods. The subsequent course of the air is precisely similar to that of
the products of combustion already described, the heated air being finally drawn
into the fire grates for the combustion of the fuel.
The details of the construction of the kiln, the number of waggons and the
number of the partitions are determined by the temperature to be attained, the
fragility of the goods to be fired and the daily out-put required.
The fire grates are closed as well as possible, either by doors or by an accumula-

page_text: tion of fuel in order that they may be fed only by heated air. A continuous.
stoking process may also be adopted and the grate closed like a producer.
The access of the heated air above, and below the bridge being capable of
regulation, the furnace becomes a gas producer and there can be obtained at
will an oxidising, neutral or reducing atmosphere, accordingly as much air is
admitted above the bridge and little to the ash pan and vice versa.
The grate is so constructed that the gases become intimately mixed before
their entry into the kiln; thus their combustion can be regulated as nearly as
possible to occur in the midst of the goods. The gases from the grate pass over
the bridge where they are met perpendicularly by the heated air escaping there-
from; the intermixture of gas and air is thus very perfect.
When it is found desirable to construct the kiln of such dimensions that owing
to friction and the fall of temperature of the gases the natural draught of the
chimney is insufficient, the draught can be increased by a fan or by a supple-
mentary furnace at the foot of the chimney.
The waggons are attached or not accordingly as the railway is inclined or
horizontal, as the waggons are held back at the entrance or at the exit and as
they are drawn or pushed. It is preferable to make the railway on an incline
and to hold back the waggons at the entrance of the tunnel by a suitable brake,
which may be worked by the fan which excites the draught. The brake may
consist of a chain and sprocket wheel on the shaft of the fan, the chain engaging
with sprocket wheels on the axles of the waggons.
The speed of the waggons may be varied with the degree of firing required
and the kind of goods being fired.
The railway consists of rails which are continuous from end to end; they are
firmly fixed by the end at the entrance and can slide in guides and expand in
length towards the exit; outside the furnace the rails are powerfully stretched.
As the waggons always more in the same direction they tend to push the rails
always towards the stretcher and dilatation is consequently not hindered.
The railway can also be constructed with hollow rails laid in the usual
manner and supporting smooth, stretched, continuous cables on which the waggons
roll.
The metallic parts of the waggons are allowed room for expansion at those
places where the temperature is high. The circulation of the hot gases is always
above the refractory platform. The joint between the refractory hearths of each
pair of waggons is in the form of a mortise.
Loss of heat by radiation between the walls of the kiln and the hearth is pre-
vented by a row of bricks projecting from the wall engaging in a mortise in
the side of the refractory hearth of each waggon.
To prevent access of cold air between the hearth and the walls, the waggons
carry on each side outside the wheels a metal plate which travels with its lower
edge in a ridge of sand placed on each side of the tunnel and fed by openings
in the sides.
D
C T
1000
ABEL & IMRAY,
Agents for the Applicant.
Improvements in Continuous Kilns or Ovens with Travelling Hearths
for Firing Ceramic Goods.
I, CHARLES DENTON ABEL, of Birkbeck Bank Chambers, Southampton Build-
ings, Chancery Lane, in the County of London, Consulting Engineer and Chartered

page_text: Patent Agent, do hereby declare the nature of this invention (which has been
communicated to me from abroad by La Société Anonyme des Faienceries de
Creil et Montereau and Ernest Gabriel Faugeron, Engineer, both of Montereau,
Seine et Marne, France) and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement:-
The continuous kilns or ovens having travelling hearths which have been
proposed heretofore for firing ceramic goods do not sufficiently utilise the heat
of combustion of the fuel and are unsatisfactory both from the point of view
of the progressive and uniform heating and cooling necessary for ceramic goods
and from the point of view of the smooth conveyance of fragile articles often
placed in apposition of unstable equilibrium.
By this invention the first named desiderata are obtained by a special arrange-
ment of the arch and walls of the kiln and by refractory partitions which travel
with the goods to be fired, the general construction being such that the products
of combustion traverse successively and uniformly all the goods to be fired and
are followed in a similar way by the air necessary for cooling the said goods.
The last above named desideratum, namely smooth conveyance, is obtained by
rolling the waggons on continuous rails without stopping them. The rails are
preferably on a slight incline so that the waggons may travel in the kiln by
their own weight and need only be held back at the mouth of the kiln.
Figs. 1 and 1 shew respectively the right hand end and the left hand end of
a longitudinal vertical section and Figs. 2 and 24 shew the corresponding parts
of a horizontal section of the kiln. Figs. 3, 4 and 5 are sections on the lines 3–3
(Fig. 2) 44 and 5-5 (Fig. 1^) respectively drawn to a larger_scale.
The kiln is a long straight tunnel of which the arch is in places depressed
and the walls are traversed by flues some of which establish a communication
between the inside of the tunnel and the outside, others with the fire grates A
and others with the chimney B. The said fire grates are on each side of the
tunnel at about the middle of its length. The train of waggons W1 W2 W³ &c.
travels through this tunnel, say from left to right, each carrying a refractory
partition at one end.
The form of these partitions is that of the reduced cross section of the tunnel
at its entrance and at the places T, U, V, X, Y, Z where the arch is depressed, so
that they act as baffles at these places. The partitions may be constructed of
one piece or of separate pieces or may be constituted by the goods themselves
or by saggers, in the latter case the goods or saggers should rest directly on the
waggon, not on blocks. It is preferable to make the partitions of two pieces
which can be lightly supported against the piles of saggers.
The baffling function should be as perfect as possible at the entrance, so as
to hinder access of cold air, and at the depression V immediately to the right of
the fire grates, so as to divide the firing part of the furnace from the cooling
part.
The entrance of the tunnel being always cold, may be lined with plates of
sheet iron, or of any other suitable material, laid parallel with the interior walls
and sufficiently closing the space between the partitions and the walls. It is
desirable that the depression at this part of the furnace should be long enough
to allow several partitions C, C1, C2, D3, D, D to act as baffles, so as to diminish
the chances of air entering and reaching the chimney, which is at this end of
the tunnel.
To form the depression V which is immediately to the right of the fire grates,
metal cannot be used on account of the high temperature. Here again the
depression is extended so as to multiply the number of partitions which act as
baffles for a purpose to be presently described. Otherwise the necessity for
complete baffling is not so great at this point as at the entrance, since the small
quantity of air which can pass will do no harm because it will be heated by
contact with the fired goods.
The flames from the lateral fire grates A A enter the tunnel through ports c c c

page_text: on each side placed at a level above the refractory platforms of the wagons WW
The saggers or the goods are placed on blocks which are a little higher than
the ports so that the flames enter among the goods from beneath and travel up-
wards and heat them. The products of combustion then pass over the partition
to the left, downwards among the goods on the next waggons, and out into a
flue in the wall of the furnace through ports c¹ cc opening thereinto at the
level of the waggons WW. They are drawn in this direction by the chimney
draught, being prevented from travelling along the arch of the tunnel by a
depression V which is of such a length that there is always a partition & passing
under it and thus forming a baffle.
The flue a in the wall conveys the products of combustion from the ports c¹ cl c¹
past the baffle and to the ports situated at the level of the bottom of the
next waggons WW through which ports they enter and ascend among the
goods. The same course is repeated the baffle E and the flues a serving the
same functions as G and a¹; the gases thus gradually part with their heat to
the goods or saggers until the entrance is reached. Here the depression of the
tunnel which forms the baffles with the partitions is a plate S which leaves a
passage R between it and the arch of the tunnel the gases pass along this passage
and down suitable flues a³ in communication therewith and situated at the sides
of the tunnel, before they arrive at the chimney. Thus this portion of the
tunnel plays the part of a muffle through which the waggons pass as they enter
the furnace. For facilitating the transmission of the heat from the flues, the
walls are made of hollow bricks, as shewn in vertical and horizontal section in
Figs. and 7 respectively.
In that part of the tunnel where the waggons are most highly heated it is
necessary to provide plugged spy holes z in the walls to permit of the course
of the firing being watched.
The cooling of the fired goods and the recovery of their heat are effected in
the following manner. Immediately to the right of the fire grates there is a
depression V sufficiently long to form several baffles with the travelling parti-
tions III 13 of waggons WW7 and this portion of the tunnel has no com-
munication with the flues in the walls, so that it is in effect a closed chamber
the contents of which can cool solely by radiation, and conduction, except in so
far as circulation of air is possible owing to the imperfection of the baffles. The
cooling of the goods in the part of the tunnel beyond the long depression V
occurs on exactly the same principle as that underlying the heating of the goods
described above. The end of the tunnel has a depression Z which forms a baffle
with the partition which happens to be passing out The air, drawn by the
draught of the chimney passes into flues bb in the walls and thence through
ports in the walls at the level of the waggons; it then passes up through the
goods becoming heated during its passage and cooling the goods. The sub-
sequent course of the air is precisely similar to that of the products of combustion
already described, the heated air being finally drawn by way of ports cloc³ &c
and flues 364 into the fire grates for the combustion of the fuel.
By appro-
priate valves the heated air is distributed to enter in part below the bridge at h
and in part above at 9.
The details of the construction of the kiln, the number of waggons and the
number of the partitions are determined by the temperature to be attained the
fragility of the goods to be fired and the daily output required.
The fire grates are closed as well as possible either by doors or by an accumula-
tion of fuel in order that they may be fed only by heated air. A. continuous
stoking process may also be adopted and the grate closed like a producer.
The access of the heated air above and below the bridge being capable of
regulation the furnace becomes a gas producer and there can be obtained at
will, an oxidising neutral or reducing atmosphere, accordingly as much air is
admitted above the bridge and little to the ash pan or vice versa.

page_text: The plates the former of which stands on the ground and the latter on
a bracket K close the furnace and prevent access of atmospheric air.
The grate is so constructed that the gases become intimately mixed before
their entry into the kiln thus their combustion can be regulated as nearly as
possible to occur in the midst of the goods. The gases from the grate pass
over the bridge where they are met perpendicularly by the heated air escaping
therefrom through the ports ii, and immediately mingle therewith the inter-
mixture of gas and air being perfected by their striking the arch and wall f of
the furnace.
When it is found desirable to construct the kiln of such dimensions that
owing to friction and the fall of temperature of the gases the natural draught
of the chimney is insufficient, the draught can be increased by a fan or by a
supplementary furnace at the foot of the chimney.
The waggons are attached or not accordingly as the railway is inclined or
horizontal as the waggons are held back at the entrance or at the exit and as
they are drawn or pushed. It is, preferable to make the railway on an incline
and to hold back the waggons at the entrance of the tunnel by a suitable brake,
which may be constituted by the fan which, excites the draught. This brake
retains the axles of the waggons by means of an endless chain working on a
sprocket wheel on the shaft of the fan, the chain having hooks or projections
which engage with the axles of the waggons.
The speed of the waggons may be varied with the degree of firing required
and the kind of goods being fired.
The railway consists of rails which are continuous from end to end; they are
firmly fixed by the end at the entrance and can slide in guides and expand in
length towards the exit, outside the furnace the rails are powerfully stretched.
As the waggons always move in the same direction they tend to push the rails
always towards the stretcher and dilatation is consequently not hindered.
The railway can also be constructed with hollow rails laid in the usual manner
and supporting smooth stretched continuous cables on which the waggons roll.
The metallic parts of the waggons are allowed room for expansion at those
places where the temperature is high. The circulation of the hot gases is always
above the refractory platform. The joint between the refractory hearths of each
pair of waggons is in the form of a mortise ooo.
Loss of heat by radiation between the walls of the kiln and the hearth is pre-
vented by a row of bricks m projecting from the wall engaging in a mortise n
in the side of the refractory hearth of each waggon.
To prevent access of cold air between the hearth and the walls, the waggons
carry on each side outside the wheels a metal plate which travels with its
lower edge in a ridge of sand placed on each side of the tunnel and fed by
openings in the sides t.
Having now particularly described and ascertained the nature of this
invention, and in what manner the same is to be performed, I declare that what
I claim is:
1. A continuous kiln with a travelling hearth for firing ceramic goods either
naked or in saggers, consisting of a tunnel the arch of which is depressed at
certain places, in combination with waggons which carry the continuous hearth
of the oven having vertical partitions, each of which partitions has a superficies
as nearly as possible equal to that of the reduced cross section of the tunnel at
the places where the arch is depressed, so that gases can pass freely round the
partitions only at those parts of the tunnel where the arch is not depressed,
the said tunnel having fire grates at about the middle of its length and a
chimney at one end and being arranged and operating substantially as and for
the purposes described.
2. In a kiln such as is referred to in Claim 1 a tunnel with horizontal flues
and with an arch depressed at certain places in combination with waggons carry-

page_text: ing vertical partitions the distance between which partitions is so related to the
length of the said depressions of the arch that at least one partition is beneath
each depression so that in passing along the arch of the tunnel the gases must
descend on one side of each depression travel horizontally beneath the depression
and ascend on the other side substantially as described.
3. In a kiln such as is referred to in Claim 1 the construction of the part
where the chimney is situated in the form of a muffle by depressing the arch of
the tunnel at this part for a length covering several partitions of the waggons
substantially as described.
4. In a continuous kiln heated by solid fuel a gas producer grate the air sup-
plied to which is heated by the fired goods and is distributed by means of flues
with regulators at the fire bridge and beneath the furnace grate substantially
as described.
5. In a continuous kiln such as is referred to in Claim 1 the use of continuous
rails, substantially as described.
6. In a kiln such as is referred to in Claim 1 a tunnel built on an incline
the gradient of which is such that the descending waggons are efficiently braked
by engaging them with a chain geared with a ventilating fan whereby a con-
tinuous and smooth travel of the waggons is insured, substantially as described.
Dated this 15th day of March 1899.
ABEL & IMRAY,
Agents for the Applicant.