JPH0247679B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to long carbon products having a substantially uniform cross section, such as carbon electrodes used in electric melting furnaces or lining blocks, anode members and cathode members in aluminum production electrolyzers. The present invention relates to a firing furnace for continuously manufacturing. These elongated carbon articles may have a circular, rectangular or any other shaped cross-section.

A green carbonaceous electrode paste consisting of a carbon material and a carbonaceous binder is filled into a casing having a cross-section corresponding to the cross-section of the carbon article to be produced, and the casing is supplied with thermal energy. Methods of manufacturing elongated carbon articles are known in which the green electrode paste is continuously fired to obtain a solid carbon article by continuous or substantially continuous lowering through a firing furnace. It is also known to use perforated casings to allow the gases generated in the electrode paste by heating to flow from the electrode paste into a firing furnace where they are combusted.

The gases generated during heating of the electrode paste and flowing into the kiln through the perforations in the casing condense in the upper part of the kiln, where the cold electrode casing containing the cold electrode paste enters the kiln. It is recognized that there is a tendency. This condensate, consisting of a large number of different hydrocarbon fractions, is eventually carbonized in the upper part of the kiln, a layer of hard carbonized material gradually forms, and after a certain time the kiln and electrode The paste will completely fill the annular zone between the casings. As a result, after several weeks of operation of the furnace, it is no longer possible to move the casing and thus the electrodes within the firing furnace. It is therefore necessary to observe the growth of a layer of hard carbonized material in the upper part of the kiln more or less continuously, and after a certain time the kiln process must be stopped, and The kiln must be removed to remove the carbide layer.
During the removal of the carbide layer, the firing zone in the carbon article is cooled, resulting in non-uniformity in the long carbon article.

If the firing furnace is operated in direct connection with an electric melting furnace for manufacturing carbon electrodes used directly in the melting furnace, the operation of the melting furnace may be interrupted while the layer of carbonized material in the firing furnace is removed. Must be canceled. This results in a loss in the production capacity of the melting furnace and
Moreover, if parts of the electrode with such inhomogeneities as described above were inserted into the melting furnace, there would be a great risk that the electrode would break.

One of the objects of the present invention is to provide a firing furnace in which hard carbonized substances are not formed in the upper part of the firing furnace.

Another object of the present invention is to prevent gas leakage from the firing furnace to the surroundings by effectively sealing the gas between the electrode casing and the upper part of the firing furnace.

Accordingly, the present invention provides a firing furnace for continuously producing elongated carbon articles having a substantially uniform cross-section, the firing furnace comprising: in the context of the elongated article;
The present invention relates to a firing furnace that moves the elongated article continuously or substantially continuously at a speed corresponding to a preset firing speed.

According to the invention, the kiln consists of a steel shell and a refractory lining located inside the shell and forming a combustion chamber around the carbon article being manufactured. A cooling chamber is provided between the upper part of the refractory lining and the carbon article being manufactured, and the lower part of the cooling chamber extends into the combustion chamber, while the upper part of the cooling chamber extends into the combustion chamber. Extends above the refractory lining. A channel is provided in the lower part of the combustion chamber for exhausting gas from the combustion chamber.

Preferably, the cooling chamber has internal channels for coolant circulation. A guide ring for guiding the carbon article into the firing furnace and a gas sealing member for preventing gas leakage from the combustion chamber are provided above the cooling chamber. The gas seal is a flexible gas seal located between a vertically disposed lower flange fixed to the top plate of the cooling chamber and a vertically disposed upper flange fixedly attached to another plate. It is preferred to have a gasket, the distance between the upper and lower flanges and thus the tightness of the gasket to the carbon article being adjustable by a plurality of bolts.

The firing furnace according to the present invention will be further explained with reference to the drawings showing specific examples of the present invention.

In FIG. 1, a firing furnace 1 for producing long carbon articles 2 is shown. This kiln is arranged around a casing 3 for the carbon article 2. This casing 3 has a cross section that corresponds to the cross section of the carbon article.

The casing 3 is filled with an unfired carbonaceous electrode paste 4 made of a carbon material and a carbonaceous binder. By heating the electrode paste 4 in the firing furnace 1, the electrode paste is fired to form the solid carbon article 2. The casing 3 is preferably provided with perforations (not shown) in order to allow the gases generated during heating of the electrode paste to flow through the perforations into the firing furnace.

The kiln 1 consists of an outer shell 5 and a refractory lining 6 forming a combustion chamber 7 . The combustion chamber 7 is heated to the temperature required for firing by at least one burner 8 for solid, liquid or gaseous fuel.
Preferably, one or more burners 8 are arranged tangentially with respect to the combustion chamber 7.
The burner 8 has supply lines 9 and 10 for fuel and combustion air. Below the refractory lining 6,
A channel 11 is provided for the exhaust gas from the kiln 1. Exhaust gas is sucked out of the channel 11 through an exhaust gas pipe 12. The exhaust gas pipe 12 is provided with a valve 13 that adjusts the volume of exhaust gas from the firing furnace.

Channel 11 has a central opening with a diameter slightly larger than the diameter of the fired carbon article. There will therefore be a slot 14 between the channel 11 and the casing 3 for the carbon article 2. When the kiln 1 is in operation, ambient air is drawn in through the slot 14, thereby creating a seal so that gases from the combustion chamber 7 are prevented from escaping through the slot 14.

In the upper part 15 of the refractory lining 6 of the kiln 1, an opening for the casing 3 is provided. This opening has a cross section that is somewhat larger than the cross section of the casing 3. In the annular slot between the upper part 15 of the refractory lining and the casing 3 a cooling chamber 16 is provided for circulating the coolant.
This cooling chamber 16 has a supply pipe 17 and a return pipe 18 of coolant, preferably water. Cooling room 16
is divided into compartments, and each compartment supplies the coolant to a cooling chamber 16.
It may have an inner wall (not shown) to provide adequate flow therein.

The cooling chamber 16 is provided such that its lower end is approximately at the same level as the lower end of the upper part 15 of the refractory lining 6, as shown in FIG. The cooling chamber 16 includes at least the upper part 1 of the refractory lining 6.
The upper end of 5 extends upward to a certain level.

The cooling chamber 16 is fixed to the outer shell 5 via an annular plate 20, and this annular plate is fixed to the outer shell 5 by bolts 21.

When the firing furnace 1 is directly connected to an electric melting furnace and used for firing carbon electrodes, it is preferable to insert an electrically insulating part 25 between the outer shell 5 of the firing furnace 1 and the annular plate 20. .

Mounted above the cooling chamber 16 is a guide ring 22 made of iron rods or the like. The purpose of this guide ring is to guide the casing into the kiln. Guide ring 2
A gas sealing device 23 is provided in the upper zone of the casing 3 and the firing furnace 1 to prevent gas leakage between the casing 3 and the firing furnace 1.

Gas sealing device 23 is shown enlarged in FIG. This device 23 has a lower annular plate 24 fixed to the cooling chamber 16. Attached to the plate 24 are two vertical annular flanges 26, 27. A flexible gasket 28 made of a material with a high melting point is fixed between these flanges 26 and 27. The upper end of the gasket 28
Annular vertical flange 2 connected to annular plate 31
It is fixed between 9 and 30. Second annular plate 31
a plurality of threaded bolts 3 having handles 33;
2 to the flange 26. By manipulating the handle 33 to adjust the distance between the first plate 24 and the second plate 31, the flexible gasket 28 is tensioned or relaxed. Gasket 2
8 can be adjusted locally around the casing 3 by operating the handle 33.

In operation, the firing furnace 1 is moved continuously or substantially continuously with respect to the casing 3 at a speed corresponding to a predetermined firing rate for the carbon article 2. When the casing 3 filled with green electrode paste 4 enters the firing furnace 1, the electrode paste is heated and then becomes liquid.
The paste is then fired into a solid carbon article.

During firing, carbonaceous gas is generated in the electrode paste. These gases enter the kiln 1 through the perforations in the casing 3 and the majority of these gases are immediately combusted by the combustion air supplied to the kiln.

However, some of the gas condenses in the cooling zone 19 on the lower vertical part of the cooling chamber 16, which is maintained at a temperature below 400 DEG C. by the coolant circulating within the cooling chamber 16. The temperature of the firing chamber is 700℃
and 1300° C., the portion of the gas in contact with the cooling zone 19 will condense. However, the temperature in this zone of the cooling chamber 16 is so low that the condensed gas will not be carbonized. The condensed gas will therefore fall into the combustion chamber where it will be immediately combusted. The cooling chamber also ensures that the gas in the annular section between the casing 3 and the cooling chamber is kept at a lower temperature. Gasket 28 is thereby protected from exposure to high temperatures. Thus, the life of gasket 28 will be increased.

According to the invention, therefore, a kiln is provided which can be operated for a very long period of time without operational difficulties due to the formation of layers of carbonized material. Furthermore, the gas sealing between the carbon article and the kiln is very good, thereby minimizing the leakage of dangerous gases from the kiln to the environment.

[Brief explanation of drawings]

FIG. 1 shows a firing furnace according to the invention. FIG. 2 is a partially enlarged view of FIG. 1. DESCRIPTION OF SYMBOLS 1... Firing furnace, 2... Long carbon article, 3... Casing, 4... Electrode paste, 5... Outer shell, 6
...Refractory lining, 7...Combustion chamber, 10...
Tube, 11... Off-gas channel, 16... Cooling chamber, 23... Gas sealing device, 26, 27... Vertical lower flange, 28... Flexible gasket, 2
9, 30... upper flange, 32... multiple bolts.

Claims (1)

[Scope of Claims] 1. A firing furnace for continuously producing elongated carbon articles having a uniform cross section, the furnace continuously producing elongated carbon articles having a uniform cross-section, the furnace continuously producing elongated carbon articles having a uniform cross-section, and continuously producing elongated carbon articles in relation to a casing containing a green carbonaceous electrode paste. or a firing furnace of the type in which the carbon article is moved substantially continuously at a speed corresponding to a preset firing speed, the firing furnace comprising a steel shell 5 and an inner side of the shell 5; a cooling chamber 16 provided between the upper part 15 of the refractory lining and the casing 3; a gas sealing device 23 provided above the cooling chamber 16; and a gas sealing device 23 provided below the lining 6. A firing furnace for the continuous production of elongated carbon articles, characterized in that it comprises an exhaust gas channel 11 provided therein, and a combustion chamber 7 is formed by the lining 6. 2. A kiln according to claim 1, wherein the lower end 19 of the cooling chamber 16 is at substantially the same vertical level as the lower end of the upper part of the refractory lining 6. 3. The firing furnace according to claim 1, wherein a guide ring 22 for guiding the casing 3 is provided in an upper part of the cooling chamber 16. 4. Gas sealing device 23 consists of a flexible gasket 28 provided between vertical lower flanges 26, 27 fixed to plate 24 and vertical upper flanges 29, 30 fixed to plate 31; , 30 is adjustable. 5 Lower flanges 26, 27 and upper flange 2
5. The firing furnace according to claim 4, wherein the distance between the two bolts 9 and 30 can be adjusted by a plurality of bolts 32. 6. A kiln according to claim 1, wherein the kiln has at least one burner 8 for solid, liquid or gaseous fuel. 7. The firing furnace according to claim 6, wherein the burner 8 is provided in a tangential direction with respect to the combustion chamber 7. 8. The firing furnace according to claim 1, wherein the firing furnace 1 is provided with at least one pipe 10 for supplying combustion air to the combustion chamber 7.