US3489400A

US3489400A - Ceramic kilns with car and door

Info

Publication number: US3489400A
Application number: US734585A
Authority: US
Inventors: Herbert Spitzbart; Manfred Schmidt
Original assignee: Keller Ofenbau GmbH
Current assignee: Keller Ofenbau GmbH
Priority date: 1967-06-07
Filing date: 1968-06-05
Publication date: 1970-01-13
Anticipated expiration: 1987-01-13
Also published as: DE1558063B1

Description

1 Jan. 13, 1970 H. S|I=ITTZBART ET-AL 3,489,400

CERAMIC KILNS WITH CAR AND DOOR Filed June 5, 1968 2 Sheets-Sheet 1 Jan. 13, 1970 H. SPITZBART EI'AL 3,489,400

CERAMIC KILNS WITH CAR AND DOOR Filed June 5, 1968 2 Sheets-Sheet '2 TORNEY5 United States Patent 3,489,400 CERAMIC KILNS WITH CAR AND DOOR Herbert Spitzbart, Ibbenbiiren, and Manfred Schmidt,

Rheine, Germany, assignors to Keller Ofenbau GmhH,

Laggenbeck, Westphalia, Germany, a joint-stock company of Germany Filed June 5, 1968, Ser. No. 734,585 Claims priority, application Germany, June 7, 1967,

K 6 ,49 Int. Cl. F02m 37/00 U.S. Cl. 263-28 10 Claims ABSTRACT OF THE DISCLOSURE A furnace for coarse ceramic articles has provision for the movement of trolleys or trucks carrying the articles in one direction whilst the combustion gases move through the furnace in the opposite direction. At the outlet end for the combustion gases (inlet end for the trolleys carrying the articles) a flue is provided for the exhaust of the combustion gases and, in order to improve the distribution of hot gases through the charges of articles a vertically movable shutter is provided which blanks off the space between the uppermost portions of the charges on the trucks and the roof of the furance.

BACKGROUND OF THE INVENTION Field of the invention The invention relates to a kiln for the ceramic industry, in particular a tunnel kiln for the coarse ceramic industry with at least one kiln door arranged at the feed end of the kiln and mounted so as to be movable transversely of the cross-section of the kiln, there being provided in the region of the kiln roof at least one discharge device for discharging combustion and other gases from the tunnel kiln. The invention also relates to a process for exhausting flue gases from the feed end of a kiln.

Owing to the flow conditions of the combustion gases generated in the combustion chamber through the charge material, the shape of the individual ceramic pieces, their mode of support and their density, which factors are different over a section at right angles to the axis of the furnace, substantially differing temperatures are, in part, set up, as a result of which the rate of temperature variation is affected unfavourably. Particularly in the region of the marginal gaps between the kiln masonry and the charge, or the charge and the kiln roof, an intensified progression of the temperatures in the charge material may be observed, while the temperatures in the heart of the charge material or batch main remain relatively unchanged.

During the withdrawal of the flue gases from the combustion chamber adjacent the feed end of the kiln through flues arranged in the lateral furnace masonry, the divergence of the temperatures over the cross-section at right angles to the axis of the kiln is intensified, as the exhaust flues terminate in the lateral marginal gaps and increase suction in those gaps.

Description of the prior art To equalise the temperature distribution, it is known that the flow of combustion gas in the warming up zone of the kiln can be influenced by the fact that the tunnel kiln truck platform is also included in the suction, the exhaust flue openings being arranged roughly on a level with the platform, while in the tunnel kiln truck platform horizontal ducts at right angles to the axis of the kiln, communicate with the charge space. Since the flue apertures nevertheless end in lateral marginal gaps, the flow ice of combustion gas within the gaps in the charge material is influenced only to a slight extent, so that a considerably divergent distribution of temperature remains.

The further proposal has been made, by loosening the charge, to equalise the flow over the cross-section of the combustion chamber at right angles to the axis of the kiln, in order thereby to reduce the divergence of the temperatures. Even this process only renders possible an improvement of the temperature distribution within relatively narrow limits, since a loosening of the charge corresponding to the marginal gaps with their large free cross-sections of flow cannot be obtained by the gaps or only with an unacceptable loss of combustion space.

Even the incorporation of stoking slits provided in the charge with suitable firing in the combustion gas suction through a gas flue arranged in the lateral kiln masonry is not able appreciably to prevent the divergence of the temperatures over the section at right angles to the axis of the kiln, since here the roof gap between the roof of the kiln and the upper face of the charge is further included in the suction, whereby the temperature distribution in that zone is rendered more unequal. Apart from this, this process for influencing the flow of flue gas is only applicable in individual cases where owing to the kiln firing, stoking slits are provided in the charge material.

The prior proposals furthermore include a device in tunnel kilns for supplying or carrying off combustion gases from the combustion chamber. This device is formed essentially by the kiln door arranged at the feed or inlet end of a tunnel kiln, which in this known form of construction is formed in the shape of a hollow box and in the region of the part facing the kiln bed and the combustion chamber has apertures for the passage of the combustion gases. With this hollow kiln door, a suction fan is connected via ducts and it draws off the combustion gases that have flowed into the door.

Owing to the particular construction of this known device, the suction fan must first be switched off during the feed sequence. A further drawback of this known device resides in the fact that the kiln door must be given a relatively heavy and complicated form, and moreover no guarantee is furnished that the temperature in the region of the roof gap will not be higher than elsewhere in the kiln, which results in the temperature differences in the charge hereinbefore described.

An object of the invention is to provide a kiln for the ceramic industry, in particular a tunnel kiln for the coarse ceramic industry, in which even in the zone of the roof gap a temperature excess need not raise, and there is moreover no risk of a wedge of non-heated charge being formed, as is the case in those constructions where the removal of flue gases is effected by a lateral flue. It is a further object of the invention that the kiln door and the parts of the device serving to discharge the combustion gases should be given a simple form. It is a still further object of the invention to provide a suitable method for operating a kiln constructed in accordance with the invention, in particular a tunnel kiln for the ceramic industry.

SUMMARY OF THE INVENTION For the kiln these objects are achieved according to the invention by arranging within the kiln at a distance from the kiln door a movable shutter which blocks at least the free cross-section of flow in the region of the kiln roof or the upper portion of the charge, while there are allotted to the shutter on the side facing the kiln door, preferably guide vanes for the combustion and other gases. In this way the differential of the combustion gases and thus the differential of the temperature in the zone of the roof gap is avoided, which results in a corresponding temperature equalisation within the charge. Furthermore, by blocking the upper cross-section of flow or the roof gap, the combustion and/or other gases are compelled to find their way through the charge, and the shutter can be so arranged that the flow of combustion gases is directed downwards towards the door arranged at the feed end of the kiln.

Owing to the fact that the shutter is movable in the combustion chamber, it can be so adjusted during the feed sequence that it does not prevent the sliding of the kiln trolleys or trucks. Furthermore, the shutter can thus be moved into the most favourable position in each case.

The guide blades make possible a particularly low resistance to How of the combustion gases and the guide blades can without diificulty be adjusted so that they divert the combustion gases to the discharge device which is arranged in the region of the feed end of the kiln.

In a particularly advantageous form of carrying out the invention, the shutter is arranged between the kiln door and the first charge of the kiln truck or trolley nearest the kiln door. The result of this is that the combustion gases flow through all the charges. Since the free space, particularly adjacent the roof gap is blocked by the shutter, the still warm or hot combustion gases are forced to flow through the charges of the kiln trucks that have just been fed in and to pre-heat these.

According to a further characteristic of the invention, the shutter is movable in a substantially vertical plane. With this arrangement of the shutter, the roof .gap between the charge and the kiln roof can be blocked particularly readily and thus the undesirable temperature differential can be precluded.

At least one suction pipe for the combustion or other gases in which a suction fan is disposed preferably terminates in the region of the roof between the kiln door and the shutter.

A further characteristic resides in the fact that the guide blades are directed or curved towards the suction pipe.

In a preferred practical embodiment in accordance with the invention, the kiln door is provided with a sealing blade or flap adjustable in the longitudinal direction of the furnace and arranged to rest on a portion of a kiln truck or trolley platform. By means of such a sealing blade or flap the position of the truck or trolley can easily be corrected for instance in relation to the firing spaces and the firing holes, so that on the one hand the stroking slits lie exactly below the firing holes, and on the other hand the sealing flaps can be adjusted so that the seal between the kiln truck and the kiln door is in no way impaired.

Preferably the kiln door, its sealing flap and the kiln roof on the one hand and the shutter or the first part of the charge of the first furnace truck on the other hand, enclose a space of large cross-section, into which protrude the guide blades that are arranged in particular on a movable shutter component. This space serves to collect the combustion gases, the guide blades and shutters being capable of adjustment so that the combustion gases in the region of the feed end of the kiln flow through the lower end of the charges.

In embodiments where the kiln according to the invention is provided with a vertically movable door, there is produced a particularly advantageous form of execution according to the invention when the sealing blade or flap in the open position of the kiln door closes the mouth aperture of the suction pipe or at least throttles. down the suction. In this way, the suction fan does not have to be switched off during the feed sequence or during the opening of the kiln door.

According to a further characteristic in accordance with the invention, the angular positions of the guide blades are adjustable. The guide can in this way be given the most favourable position.

Since during the feed sequence or on opening of the kiln door, the shutter must also be moved into a position such that it does not impede the movement of the kiln trucks it is desirable to provide between the kiln door and the shutter or the guide blades, a coupling for moving these parts in the same direction. This coupling can for example take the form of a rod which can be actuated externally of the kiln and by which the shutter, the guide blades and the furnace door can be moved, it necessary at the same time.

The invention furthermore relates to a process for discharging flue gases in the region of the feed end of a kiln in particular a tunnel kiln of the ceramic industry. The method is characterised by the combination of the following features:

(a) The combustion gases are passed in the region of the feed end of the kiln in the direction of the kiln door downwards through the charges.

(b) In front of the kiln door the combustion gases are diverted approximately at right angles to the kiln roof.

(c) The flue gases are drawn off in the region between the kiln door and the first part of the charge of the first kiln truck or trolley.

This method renders possible on the one hand particularly gentle warming of the freshly inserted charges; on the other hand with this method, the temperature differential especially in the region of the roof gap is sub stantially eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of a tunnel furnace, for use, for example, in the coarse ceramic industry will now be described by Way of example, with reference to the accompanying diagrammatic drawing, in which:

FIG. 1 shows the green material inlet end of the tunnel kiln in longitudinal section; and

FIG. 2 is an end elevation of the kiln of FIG. 1, one half being illustrated with a door of the kiln raised and the other half in the closing position.

A tunnel kiln 1 of which, from the drawing, only the inlet end is shown in some detail is normally sealed by a vertically movable kiln door 2. The door 2 carries two

rotatable rollers

2b, 20 which are movable along respective

rectilinear guides

15, 16. As can be seen from FIG. 1, the guides extend vertically and parallel to the door itself but at their respective lower ends each guide has a short inclined section which enables the door to be located in its correct seating position relatively to the inlet and in particular against an upper horizontal support 25. The vertical movement of the door 2 is effected by cables 17 and an electric motor 18 mounted on a platform above the door. The cables 17 are secured to the door 2 and are arranged to be Wound around a drum (not shown) part for rotation with the motor shaft. In the longitudinal direction of the tunnel kiln 1, rails 4 run through a combustion chamber 3 on which kiln trolleys or

trucks

5a, 5b or other charge-carrying means can be moved.

The

trucks

5a, 5b carry the charge to be burnt, for example, stacks of green bricks 6, which bricks extend in a stack up to the region of the kiln roof 1a and leave merely a roof gap 7. Between the stacks 6 there are arranged firing spaces 8 Which lie below firing holes 9 (only one shown). One of the firing holes 9 contains a burner 24, for instance an oil burner for firing the kiln 1. The burner is disposed in the rear part of the kiln.

The

trucks

5a, 5b closely engage one another at the truck platforms, and seal the combustion chamber 3 from a passage (not shown) running below the tunnel kiln 1 in its longitudinal direction, and thus also from the atmosphere.

The feed direction of the

trucks

5a, 5b is indiciated by arrow X, while the combustion gases are drawn off in the direction indicated by arrow Y, in the opposite direction to the feed direction X, towards the feed end of the tunnel kiln 1.

As may be seen in particlar from FIG. 1, in front of the first stack 6 of the first truck 5a there is a space 10 of large substantially rectangular cross-section, which is bounded at its ends by the door 2 or the first charge 6 of the first truck or trolley 5a and by a shutter 11 or other obturating means and guide blades 12. The lower boundary of the space 10 is bounded by a sealing flap 2a which can be fixed in the horizontal direction, or else can be slid or adjusted.

The sealing flap 2a is rigidly connected with the lower end of the door 2 and, in its lower position as shown in FIG. 1 rests on a support 24 forming a part of the trolley 5a. The flap 2a forms a seal with the support 24. Upwards movement of the door 2 carries the flap 2a along and the guide blades 12 and the shutter 11 being in the path of the flap are carried upwardly. As a result of the friction between the shutter 11 and the guide blades 12 on the one hand and the guide 19 to 21, the shutter and blades remain in their upper positions.

A suction pipe 13 terminates within the space 10 adjacent the kiln roof 1a in which there is provided a suction fan 14 which is shown only diagrammatically and is driven by a motor 14a. The combustion gases are drawn by the suction fan 14 in the direction T from the space 10.

The shutter 11, is movable at least in a vertical plane in guides 19 and is adjustable so that the shutter 11 or the guide blades 12 during the movement of the trolley or on the opening of the door 2 can be moved upwards into a position such that these parts to not impede the movement of the trolleys. Moreover, the guide blades 12 are adjustably, secured in their angular position in relation to the flow of combustion gases. The guide blades 12 are slidably mounted in

vertical guides

20, 21 and limited pivotal movement is provided by semi-circular members 22 having an arcuate slot 22a and co-operating with the guide blades 12 by means of bolts and wing nuts (not shown). The members 22 are rigid with slides 23 which are slidably mounted in the

guides

20 and 21.

As may at once be seen, the roof gap 7 is closed by the shutter 11, so that the combustion gases cannot pass into this gap. The suction fan 14 draws the combustion gases through the space 10 and through the guide blades 12 through the stacks 6 and mainly through the lower third of the stacks 6.

The shutter 11 can if necessary, also be so formed that it covers not only the roof gap 7, but also the lateral marginal gaps between the change or tunnel kiln walls and in this zone also it hinders the advance of the combustion gases.

In the open position of the door 2, the sealing flap 2a closes the mouth orifice of the suction pipe 13 or shuts off the suction of the combustion gases, so that the suction fan 14 does not need to be switched oif during the feed sequence. As the sealing flap 2a can be adjusted in the horizontal direction, the trucks or

trolleys

5a, 5b can, without difliculty, be operated so that the holes 9 always occupy the desired position in relation to the firing spaces 8.

We claim:

1. In a kiln for use in firing ceramic articles,

means defining a combustion chamber,

means defining a roof of the kiln,

means for guiding charge-carrying means through the kiln,

a door arranged movably at the inlet end of the kiln for the charge-carrying means,

means for exhausting combustion gases from the kiln,

obturating means spaced from the kiln door, and serving to obstruct at least the flow of combustion gases adjacent the kiln roof whereby substantially uniform distribution of combustion gases through ceramic articles on charge-carrying means in the kiln is effected, and

a sealing flap, mounted on the kiln door and adjustable in the longitudinal direction of the kiln,

said sealing flap being arranged to rest on a portion of the last-inserted charge-carrying means.

2. A kiln according to claim 1 wherein the obturating means is disposed between the kiln door and the last said charge-carrying means to be loaded into the kiln.

3. A kiln according to claim 1 comprising means for moving the obturating means substantially in a vertical plane.

4. A kiln according to claim 1 wherein the obturating means is arranged to block the gap between the uppermost portion of the stacks of articles on the chargecarrying means and the kiln roof.

5. A kiln according to claim 1 wherein the kiln door, the kiln roof, the obturating means, the last-inserted charge-carrying means and the sealing flap together define a chamber, said chamber having guide blades mounted therein on the obturating means.

6. A kiln according to claim 5, comprising means for raising and lowering the kiln door,

said sealing flap in the open position of the door serving to close off the suction duct through which exhaust gases are drawn when the door is closed.

7. In a kiln for use in firing ceramic articles,

means defining a combustion chamber,

means defining a roof of the kiln,

means for guiding charge-carrying means through the kiln,

means for exhausting combustion gases from the kiln,

said means comprising a suction duct,

a fan disposed within the suction duct, and

means defining a chamber lying between the obturating means and the kiln door, said chamber communicating with the suction duct,

obturating means spaced from the kiln door, and serving to obstruct at least the flow of combustion gases adjacent the kiln roof whereby substantially uniform distribution of combustion gases through ceramic articles on charge-carrying means in the kiln is effected.

8. A kiln according to claim 7 comprising curved guide blades within said chamber and arranged to direct combustion gases upwardly towards the suction duct.

9. A kiln according to claim 7, comprising guide blades for deflecting combustion gases, and

means for adjusting the angular position of the guide blades.

10. A kiln according to claim 9, comprising means inter-connecting the kiln door, the obturating means and the guide blades whereby said parts can be moved in the same direction together.

References Cited UNITED STATES PATENTS 1,040,895 10/ 1912 Cowles 263-28 1,778,747 10/1930 Barnebey et al. 263-28 FOREIGN PATENTS 177,711 2/1954 Austria.

JOHN J. CAMBY, Primary Examiner US. Cl. X.R. 1 10173