IMPROVEMENTS IN POTTERY OR CALCINING OVENS OR KILNS, AND IN THE MEANS OF UTILIZING THE WASTE HEAT THEREOF, AND APPARATUS EMPLOYED IN CONNECTION THEREWITH
Year: 1876

page_text: LETTERS PATENT to Frederick Siemens, of Dresden, and Franz Hesse, of
Boehlen and Roetha, near Leipzig, both in the Kingdom of Saxony, for the
Invention of "IMPROVEMENTS IN POTTERY OR CALCINING OVENS OR KILNS,
AND IN THE MEANS OF UTILIZING THE WASTE HEAT THEREOF, AND APPARATUS
EMPLOYED IN CONNECTION THEREWITH."
Sealed the 23rd March 1877, and dated the 10th October 1876.
PROVISIONAL SPECIFICATION left by the said Frederick Siemens and Franz
Hesse at the Office of the Commissioners of Patents on the 10th October
1876.
FREDERICK SIEMENS, of Dresden, and FRANZ HESSE, of Boehlen and Roethia, near
Leipzig, both in the Kingdom of Saxony. "IMPROVEMENTS IN POTTERY OR
CALCINING OVENS OR KILNS, AND IN THE MEANS OF UTILIZING THE WASTE HEAT
THEREOF, AND APPARATUS EMPLOYED IN CONNECTION THEREWITH."
This Invention has reference to an improved construction of that description of
pottery or calcining ovens or kilns wherein the goods to be burnt are carried on a
inoveable floor made to travel slowly through a chamber wherein they are con-
secutively dried, fired, and cooled.
According to our present improvement we construct the oven or kiln of a long
straight tunnel-shaped chamber of brickwork, the travelling floor of which consists
of a number of short trucks running with wheels upon rails laid in the lower part
of the tunnel. The tunnel may be considered as being divided into three parts,
namely, first, a drying chamber at one end, into which the fresh goods are introduced;
secondly, a firing chamber in the middle, in which the goods are subjected to direct
fire heat; and third, a cooling chamber at the other end, where the fired goods are
cooled by the air passing through to the firing chamber. The drying chamber
communicates with a chimney, firstly, through lateral flues near the end; and
secondly, through a longitudinal flue extending along the roof of the entire length
of this part of the tunnel, openings being formed at certain distances apart in the
roof provided with valves or dampers, by which the watery vapours fromthe drying
goods may be made to pass directly from any part of the drying chamber to the
מ.

page_text: chimney instead of having first to pass right through the chamber, as is the case
with ovens of present construction.
The firing chamber has at one side a number of gas producers of well-known
construction for producing combustible gas, which is conducted thence through flues
provided with dampers to openings at each side of the chamber, so that the gas
issuing from such openings enters into combustion with the hot air passing in from
the cooling chamber, and thereby effects the firing of the goods on the travelling
floor. The air passes to the firing chamber partly direct through the cooling
chamber and partly through side flues communicating with the latter at certain
points through side openings and with the firing chamber through other side
openings above the gas inlets. Between the gas and air inlets on each side of the
chamber are outlets for the products of combustion provided with valves and
communicating by passages with a flue beneath the chamber communicating with
the chimney. This chamber has also a series of slides which can be lowered through
slits in the roof, so as to cut off the communication between the firing and drying
chambers at any point, whereby in conjunction with the before-mentioned side
escape flues we are enabled at any time to concentrate the heat at any desired part
of the firing chamber should the goods there situated require it.
In cases where steam power is. used on the works we place any required number
of steam boilers over the roof of the kiln, at about the inner end of the cooling
chamber, a certain portion of the highly heated air that has passed through the fired
goods being led through apertures in the roof provided with dampers into flues
surrounding the boilers, openings closed by dampers are also provided for introducing
cold air into the said flues when necessary.
The air required for combustion in the oven first enters the space below the
travelling floor at the end of the receiving chamber and after passing along the
entire length of such space, thus keeping the under framing and wheels of the
trucks cool; the air rises through passages into the end of the cooling chamber, in
traversing which it takes up heat from the fired goods there situated, thus arriving
in a highly heated condition at the firing chamber; here the air enters into combustion
with the gas, as before described, and the hot products of combustion pass through
the drying chamber, drying the fresh goods therein, and eventually escaping up the
chimney.
The trucks constituting the travelling platform are constructed of an iron framing,
between which are built flat fire-brick arches carrying fire-brick slabs constituting the
floor. In order to prevent the passage of cold air from the space below the floor to
that above it a double air-tight joint is formed between the sides of the oven and
the trucks, firstly, by iron troughs fixed on either side of the latter, filled with sand,
into which dip longitudinal plates fixed to the sides of the oven; and secondly,
below these are other iron troughs fixed to the sides of the oven filled with sand,
into which dip plates on the sides of the trucks. The trucks are coupled closely
end to end by latches, and the joints between their ends are also made air-tight by
placing fire-brick slabs upon projecting flanges on each truck and filling in the space
above the slabs with sand.
The two ends of the oven or kiln are also closed in an air-tight manner by flat
iron doors pressed by screws against an india-rubber facing let into the framing for
the door; the door at the end of the cooling chamber is extended down to the
bottom of the space below the floor, so as to close it, while that at the end of the
drying chamber terminates at the level of the floor, so as to let the cold air enter
the space below, as before described. The doors are arranged to slide up and down,
being hung by chains to counterweights for this purpose.
The rails upon which the trucks run are laid at a slight incline from the drying
chamber towards the cooling chamber, so that the loaded trucks introduced at the
end of the former will have a tendency to travel along the oven, and the necessary
power for overcoming the friction of the moving parts is supplied by a hydraulic
ram fixed at the receiving end of the oven, which ram is made to press against the
end of the truck to be introduced, thereby causing the whole line of trucks in the

page_text: oven to travel along until the truck with fresh goods has passed in, while the last
truck loaded with fired and cooled goods has at the same time been pushed out at
the other end.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Frederick Siemens and Franz Hesse in the Great Seal Patent Office on
the 10th April 1877.
FREDERICK SIEMENS, of Dresden, and FRANZ HESSE, of Boehlen and Roetha, near
Leipzig, both in the Kingdom of Saxony. " IMPROVEMENTS IN POTTERY OR
CALCINING OVENS OR KILNS, AND IN THE MEANS OF UTILISING THE WASTE HEAT
THEREOF, AND APPARATUS EMPLOYED IN CONNECTION THEREWITH."
This Invention has reference to an improved construction of that description of
pottery or calcining ovens or kilns wherein the goods to be burnt are carried on a
moveable floor made to travel slowly through a chamber wherein they are con-
secutively dried, fired, and cooled.
According to our present improvements we construct the oven or kiln of a long
straight tunnel shaped chamber of brick work, the travelling floor of which consists
of numbers of short trucks running with wheels upon rails laid in the lower part of
the tunnel. The tunnel may be considered as being divided into three parts,
namely: First, a drying chamber at one end, into which the fresh goods are intro-
duced; secondly, a firing chamber in the middle in which the goods are subjected to
direct fire heat; and third, a cooling chamber at the other end where the fired goods
are cooled by the air passing through to the firing chamber. The drying chamber
communicates with a chimney, firstly through lateral flues near the end, and
secondly through a longitudinal flue extending along the roof of the entire length
of this part of the tunnel, openings being formed at certain distances apart in the
roof, provided with valves or dampers by which the watery vapours from the drying
goods may be made to pass directly from any part of the drying chamber to the
chimney instead of having first to pass right through the chamber, as is the case
with ovens of present construction.
The firing chamber has at one side a number of gas producers of well known con-
struction for producing combustible gas, which is conducted thence through flues
provided with dampers to openings at each side of the chamber so that the gas
issuing from such openings enters into combustion with the hot air passing in from
the cooling chamber, and thereby effects the firing of the goods on the travelling
floor. The air passes to the firing chamber partly direct through the cooling
chamber and partly through side flues communicating with the latter at certain
points through side openings, and with the firing chamber through other side
openings above the gas inlets. Between the gas and air inlets on each side of the
chamber are outlets for the products of combustion provided with valves and com-
municating by passages with a flue beneath the chamber communicating with the
chimney. This chamber has also one or more slides which can be lowered through
slits in the roof so as to cut off the communication between the firing and drying
chambers at any point whereby in conjunction with the before-mentioned side
escape flues we are enabled at any time to concentrate the heat at any desired part
of the firing chamber, should the goods there situated require it.
In cases where steam power is used on the works we place any required number
of steam boilers over the roof of the kiln at about the inner end of the cooling
chamber, a certain portion of the highly heated air that has passed through the fired
goods being led through apertures in the roof, provided with dampers into flues
surrounding the boilers; openings closed by dampers are also provided for intro-
ducing cold air into the said flues when necessary.
The air required for combustion in the kiln first enters the space below the
travelling floor at the end of the receiving chamber, and after passing along the

page_text: F is the chimney of the kiln, it communicates firstly with the charging end of the
kiln through side flues G; and, secondly, with a flue H extending over the entire
length of the drying chamber A. Into this flue lead passages I, I, I, formed at
intervals apart in the roof of the kiln, so that the watery vapour rising from the
fresh goods may be allowed to escape directly through the passages I and flue H to
the chimney without having to travel right through the drying chamber to the
flue G for this purpose, whereby a more efficient and accelerated action of the
drying chamber is insured. Each of the passages I is provided with a hood or
damper which can be opened or closed through corresponding openings in the top
of the flue H, as shewn, in order to regulate the draught through the passages to the
exact extent that may be required. Other side flues K, K, establish a communication
between an intermediate point of the drying chamber and a flue L communicating
with the firing chamber for a purpose to be presently described. The firing
chamber A has on one side of it a number of gas producers M, M, of ordinary con-
struction enclosed in a side building M which also contains the fuel store.
The combustible gas passes from the producers into the main gas channel N,
whence it is conducted through flues N1, N2, provided with regulating. valves to
ports N³ on either side of the chamber, on issuing through which the gas enters
into combustion with the heated air passing into the chamber both directly from
the cooling chamber and through the ports 02, 02, situated immediately over the
gas ports to which the hot air is led through flues 01, 0', communicating with side
openings 0, 0, in the cooling chamber A². The heat produced by this combustion
effectually fires the goods in the chamber, and the hot gaseous products of combustion
escape either wholly through the entire length of the drying chamber A, imparting
their heat to the fresh goods therein, or partly or wholly through the side flues P
into the Blue L, and thence through the flues K into the chamber A.
In order to cause the whole of the products of combustion to pass in the last
named direction a slide is introduced through an opening at Q extending right
across the chamber so as to entirely cut off the direct communications between the
chambers A and A¹. By this means the heat may at any time be more directly
concentrated on the goods in the firing chamber should this be required. The
flues P are also provided with dampers by which communication with the flue L
may be cut off. Should the quantity of heated air coming from the cooling chamber
be more than is required for the combustion in the firing chamber, a portion thereof
may be utilised for raising steam in steam boilers R, R, placed on the roof of the
kiln should steam power be required on the works. For this purpose there are
formed a number of openings S in the roof of the kiln, each of which is provided
with a sliding damper so as to allow any desired quantity of the hot air to pass
through such openings into flues surrounding the boilers, whence after imparting its
heat to the latter the air escapes through flues T into the flue H, and thence to the
chimney. An opening is provided at U in the boiler flues closed by a slide, through
which, when required, cold air can be admitted into the flues in order to regulate
the temperature therein.
The space in the kiln below the platform of the trucks being separated hermeti-
cally from the space above the same in a manner to be presently described, and the
doors at the delivery end of the kiln being made to close the entire orifice as shewn
at Fig. 7, while those at the inlet end only extend down to the platform of trucks
as shewn in the detail at Fig. 11, it follows that the external air in being drawn
into the kiln by the chimney draught must enter through the opening left below the
door at the inlet end, and after passing through the entire length of the space below
the platforms of the trucks the air will rise through a space left between the end of
the last truck and the doors of the delivery end into the cooling chamber A² The
cold air in thus passing in contact with the wheels and framework of the trucks will
effectually keep these cool and preserve them from injury. On entering the cooling
chamber the air will pass through the hot fired goods contained therein, taking up
the heat therefrom and passing thence into the firing chamber A¹ in the manner
above described. The goods on the last of the trucks having become sufficiently

page_text: cooled by the passage of the cold air the door at the delivery end of the kiln is
opened and the said truck is drawn out. The door is then closed, and the door at
the receiving end being then opened a truck with fresh goods is pushed in causing
the whole line of trucks in the kiln to travel forward a stage. The fired and cooled
goods having been removed from the trucks in the enclosed space V at the delivery
end, the trucks are conveyed along the line of rails W to the enclosed space X at the
receiving end where they are again charged with fresh goods.
The construction of the trucks and the arrangements for forming double air-tight
joints between them and the sides of the kiln, as also between the contiguous ends
of the trucks will be understood on reference to Figs. 8 and 9, which shew
respectively a part transverse section of one of the trucks, shewing part of the kiln
and a part longitudinal section of a truck. The trucks are constructed of a wrought
iron skeleton framework a, a, filled in with flat fire-brick arches b, b, the thrust of
which is taken by tie bolts c, c, and above the arches one or two courses of fire-brick
are laid in order to form a level platform for receiving the goods and to interpose a
considerable thickness of refractory material between the highly heated chamber of
the kiln and the metal work of the truck.
A double air-tight joint is formed between the sides of the trucks and the kiln,
firstly by means of longitudinal troughs d fixed at the sides of the kiln, which are
filled with dry sand, ashes, or other pulverulent refractory material, and into which
dip plates e extending along the sides of the trucks, the plates of each truck being
made to overlap those of the next one; secondly, wrought-iron troughs fare fixed
against the sides of the trucks above the troughs & which are also filled with dry
sand or ashes, and into which dip plates g fixed to the sides of the kiln. The separate
lengths of the trough on the contiguous trucks are made to overlap each other so
as practically to form one continuous trough extending along the entire length of
the kiln.
The great advantage that the above described travelling trough possesses over
the fixed trough consists in the fact that the charge of sand for the former is con-
tinually being renewed, namely, every time a fresh section is added on by the intro-
duction of a new truck, and thus the sealing action of the joint is always maintained
perfect, whereas in the stationary trough the sand or ashes are liable to become
caked in course of time by the absorbtion of moisture from the kiln, and thus its
action is liable to become defective.
As it is very essential for the perfect working of the kiln that there should be a
perfectly air-tight separation between the space below the platform and the firing
chamber of the kiln so as to prevent the ingress of any cold air from the former into
the latter, an air-tight joint is also made between the ends of the continguous trucks,
as shewn at Fig. 9, by placing fire-brick slabs i upon the projecting flanges of the T
iron framing a and also closing in the spaces at the sides to a certain height with
fire-brick and then filling in the space between the platforms with dry sand or ashes.
This joint is readily made at the receiving end of the kiln at the time of introducing
cach separate truck as before described, the ends of the truck being in the first
The wrought-irou
instance locked together by latches h or other suitable means.
doors D are also made to fit more or less perfectly air-tight against the end openings
of the kiln in the manner shewn at Figs. 10 and 11, which shew respectively a
sectional plan and a part elevation of the door and framework at the receiving end.
The iron framing k fixed to the brickwork has firstly an india-rubber fillet 7 let into
an undercut groove; and secondly, a number of screws m carried by brackets, by
means of which the top and sides of the door D are pressed against the india-rubber
fillet. At the lower edge the door at the receiving end is made to fit as closely as
practicable against the end of the platform of the last truck as shewn at Fig. 11,
while the door at the delivery end fits against the ground. The doors are suspended
from chains passing over pulleys at top and provided with counterweights, and are
slid up and down vertically for opening and closing the kiln.
Having thus described the nature of our Invention and in what manner the same
is to be performed, we wish it to be understood that we do not claim generally the

page_text: construction of tunnel kilns with moveable floors formed by a number of separate
trucks that are gradually made to pass through the kiln, as we are aware that such
an arrangement was described in the Specification to Cliff's Patent, No. 1038, of
1868, but we claim in respect of such kilns,-
First. Providing a flue extending along the drying chamber of the kiln and com-
municating both with the chimney and through a number of openings with the said
chamber, so that the watery vapour may be led off from the fresh goods directly to
the chimney as they arise, substantially as herein described.
Second. Providing at the sides of the firing chamber ports and passages commu-
nicating with a flue leading to the chimney, so that a portion of the products of
combustion may be caused to pass away directly through such ports instead of
having to permeate through the whole body of fresh goods in the drying chamber,
substantially as and for the purposes herein described.
Third. In combination with the escape ports referred to in the preceding claim
the use of a slide for entirely separating the firing chamber from the drying chamber,
substantially as and for the purposes herein described.
Fourth. Providing ports and passages communicating at one end with the firing
chamber in close contiguity with the gas ports, and at the other ends with an inter-
mediate point of the cooling chamber, whereby a portion of the heated air passing
through the latter may be conducted directly to the entering currents of combustible
gas, substantially as herein described.
Fifth. Providing above the cooling chamber of the kiln one or more steam boilers
into the flues of which a portion of the hot air of the chamber may be admitted
through openings provided with regulating dampers, substantially as herein described.
Sixth. Providing for the more or less perfectly air-tight enclosure of the chamber
of the kiln excepting at the proper inlet for air at the cooling chamber by forming
air-tight joints firstly between the sides of the kiln and the trucks; secondly, between
the contiguous ends of the trucks; and thirdly, between the doors and the end open-
ings of the kiln, substantially as herein described.
Seventh. Providing at the sides of the trucks a trough filled with refractory
material in pulverulent form, into which dip plates fixed to the sides of the kiln, thus
forming a travelling air-tight joint, substantially as herein described.
Eighth. In combination with the travelling air-tight joint referred to in the pre-
ceding claim, the use of a trough fixed to the side of the kiln filled with pulverulent
refractory material into which dips a plate at the sides of the trucks, the two appli-
ances thus forming a double air-tight joint, substantially as herein described.
Ninth. Forming an air-tight joint between the ends of the trucks, substantially
as herein described with reference to Fig. 9 of the Drawings.
Tenth. Constructing the platform of the trucks of an iron skeleton framework
filled in with fire-brick arches, substantially as herein described with reference to
Figs. 8 and 9 of the Drawings.
Eleventh. The arrangements herein described with reference to Figs. 10 and 11
for closing the ends of the kiln in an air-tight manner.
Twelfth. So arranging the doors at the receiving and delivery ends of the kiln in
relation to the travelling floor that the air required for combustion in the firing
chamber is made to enter the space below the floor at the receiving end, and after
passing through the entire length of such space is made to rise at the delivery end
into the cooling chamber of the kiln, substantially as herein described.
In witness whereof, I, the said Frederick Siemens, have hereunto set my hand
and seal, this Third day of April, in the year of our Lord One thousand
thousand eight hundred and seventy-seven.