EP1845189B1 - Method for controlling temperature of ceramic elements of a support or peel guide rail in a paper producing system and device and support or peel guide rail for carrying out this method - Google Patents

Abstract

In a method for controlling the temperature of the ceramic element (1b) of a supporting or wiping strip (1) aligned with sieve or felt belt(s) in a paper-making plant, the strip is formed with at least one channel (11, 12) through which heating or cooling medium is passed. Independent claims are included for: (1) corresponding apparatus for carrying the process, in which the supporting or wiping strip (1) is formed with the channel(s) (11, 12), connected with conduits (13, 14) for supplying and abstracting the heating or cooling medium respectively; and (2) corresponding supporting or wiping strips for carrying out the process, provided with the channel(s) (11, 12) for conducting the heating or cooling medium.

Description

The subject invention relates to a method for controlling the temperature of the ceramic elements of a support or squeegee, which is assigned in a plant for paper production to the located therein at least one screen belt or at least one felt belt. Furthermore, the invention relates to a device and a support or squeegee for performing this method.

Equipment for paper production have at least one screen belt and further at least one felt belt, which are assigned to the two bands in their direction of succession, aligned transversely to the bands supporting strips over which the screen belt and the felt belt are guided. In a first area of the paper-making plant, the support strips also serve as squeegee strips for the liquids emerging from the paper pulp and passing through the sieve belt. Since these Abstützleisten are exposed to large mechanical and corrosive loads, there is a need to provide these on their the Siebbändern or the felt tapes facing surfaces with plates of a ceramic material to which the screen belt or the felt belt to the plant.

On the one hand, the screen belt or the felt belt at very high speeds of e.g. Moved 40 m / sec over the Abstützleisten away. On the other hand, there are below the support strips means for sucking the emerging from the pulp liquids or for sucking air to dry the paper belt resting on the wire belt or for drying the felt belt, whereby the wire belt or the felt on the support bars with very high pressure rest. As a result, frictional forces occur, by which the ceramic elements can be heated strongly.

As soon as the plant for paper production is out of operation, the support strips cool down to the ambient temperature. As soon as the system is put into operation, the paper pulp is sprayed onto the sieve belt, which can have a temperature of up to 90 °. Furthermore, above the screen belt, a steam hood can be provided, within which superheated steam is located, which serves to dry the paper tape and through which the ceramic elements can be subjected to temperatures up to 150 ° C. It should also be noted that the ceramic elements of the support or squeegee have a very low thermal conductivity.

Due to the circumstances outlined above, the ceramic elements of the supporting or wiper strips are subject to very high thermal stresses, which can change within a very short time within a range of about 200 ° C.

As a result of these thermal stresses, there is a risk of cracks or breaks occurring in the ceramic elements. There is a need to replace the support or squeegee immediately, otherwise the screen belt or the felt belt are damaged, whereby the production process affected and operational failures can be conditional.
Due to the circumstances described above, damage to the ceramic elements caused by high temperature fluctuations must be avoided in such systems absolutely.

From the EP 1260633 A2 as well as from the EP 1382741 A2 It is known to equip the ceramic elements of support or squeegee in paper-making plants with temperature sensors. By means of these sensors, on the one hand, the existing temperatures are to be determined and, on the other hand, rapidly changing temperatures in the ceramic elements are ascertained. This makes it possible to control the operation of the system so that impermissible temperature values or rapid changes in the temperatures of the ceramic elements are avoided.

According to the EP 1382741 A2 This control of the operation of the system is characterized in that the support or wiper blades are assigned spray nozzles through which water is sprayed onto the support or squeegee, and that the trained with Abstütz- or squeegee suction boxes are provided with vacuum lines through which of the pressure with which the screen belts abut against the support or wiper strips, can be controlled.

However, these methods do not correspond to the existing requirements for such systems, since different thermal conditions occur in different areas of the plant for paper production and in particular in the individual support or squeegee, which is why by controlling the entire system and areas of the same unacceptable thermal loads the provided on the individual support or squeegee ceramic elements can not be avoided.

The subject invention is therefore based on the object to provide a method by which the individual located in a plant for paper production support or squeegee can be protected from being damaged due to occurring in these thermal stresses. this will According to the invention achieved in that the support or squeegee is formed with at least one channel through which a carrier medium for heat or for cold is passed.

According to a first preferred method, a mixing valve is provided in the line leading to the at least one channel, are connected to which lines for carrier media for heat or for cold and which is set to the temperature which should have the respective support or squeegee , In this case, a temperature sensor may be provided in the leading away from the support or squeegee line, by which the temperature of the effluent from the supporting or squeegee carrier medium is measured. In addition, a temperature sensor can also be provided in the line leading to the support or stripping bar, by means of which the temperature of the support medium flowing toward the support or stripping bar is measured.

In accordance with a second preferred method, the temperature of the carrier medium flowing in toward the support strip or scraper blade is controlled as a function of the temperature of the carrier medium flowing away from it. In this case, the carrier medium can be conveyed by means of a feed pump in a self-contained line circuit. Furthermore, the carrier medium flowing away from the supporting or wiper strip can either be conducted via a heating device or via a cooling device, and then the support or wiper strip can be supplied. The heating device or the cooling device can be controlled as a function of the temperature of the carrier medium flowing away from the supporting or wiping strip.
Alternatively, the power of the feed pump can be controlled as a function of the temperature of the carrier medium flowing away from the support strip or scraper blade. In addition, both the performance of the heating device or of the cooling device and the power of the feed pump can be controlled as a function of the temperature of the carrier medium flowing away from the support or wiper strip. Preferably, the carrier medium is passed continuously through the supporting or stripping bar, wherein it is in particular passed through the ceramic elements of the supporting or stripping bar.

In a system according to the invention for carrying out this method for controlling the temperature of the ceramic elements of a support or squeegee in a plant for paper production, the support or squeegee is formed with at least one channel, are connected to which lines for the support or squeegee inflowing carrier medium and for this flowing from the carrier medium.
According to a first embodiment, a mixing valve for carrier media of heat and cold is located in the line leading to the at least one channel. Furthermore, a temperature sensor may be located in the line leading to the support or stripping bar and / or in the line leading away from the support or stiffening bar.

According to the second embodiment, a line system is provided, in which there are a feed pump, a heater and a cooling device for the carrier medium, wherein at least one temperature sensor for determining the temperature of the effluent from the support or squeegee carrier medium and a control unit for controlling the Benefits of the heater and the cooling device and or or the feed pump are provided. In this case, at least one temperature sensor for determining the temperature of the supporting or stripping bar supplied carrier medium may be provided.

An inventive support or squeegee for carrying out this method is formed with at least one channel for conducting a carrier medium for heat or for cold. The channel can pass through the ceramic elements. Furthermore, the channel can be located between the ceramic elements and a carrier strip for the ceramic elements. In addition, the channel may begin at one end of the support strip and terminate at the other end thereof, or the channel may begin at one end of the support strip and be returned thereto to the same end. In this case, the leading channel can be connected to the returning channel within the support or squeegee. In addition, the leading channel can be connected to the returning channel via a piece of pipe located outside the support or wiper strip. Furthermore, both the ceramic elements and the carrier strip can be formed with at least one channel or channel pieces.

The inventive method, a system according to the invention and a support or stripping strip according to the invention are explained below with reference to embodiments shown in the drawing.

• Fig.1 eine Einrichtung zur Durchführung eines ersten erfindungsgemäßen Verfahrens, in schematischer Darstellung;
• Fig.2 eine Einrichtung zur Durchführung eines zweiten erfindungsgemäßen Verfahrens, in schematischer Darstellung;
• die Fig.3 und Fig.3a eine erste Ausführungsform einer erfindungsgemäßen Abstütz- bzw. Abstreifleiste, im Längsschnitt sowie im Schnitt nach der Linie A-A der Fig.3;
• die Fig.4 und Fig.4a, 4b, 4c sowie 4d zweite Ausführungsformen einer erfindungsgemäßen Abstütz- bzw. Abstreifleiste, im Längsschnitt sowie in Schnitten nach der Linie B-B der Fig.4;
• die Fig.5 und Fig.5a eine dritte Ausführungsform einer erfindungsgemäßen Abstütz- bzw. Abstreifleiste, im Längsschnitt sowie im Schnitt nach der Linie C-C der Fig.5;
• Fig.6 eine vierte Ausführungsform einer erfindungsgemäßen Abstütz- bzw. Abstreifleiste, im Längsschnitt;
• die Fig.7 und Fig.7a, 7b sowie 7c fünfte Ausführungsformen einer erfindungsgemäßen Abstütz- bzw. Abstreifleiste, im Längsschnitt sowie in den Schnitten nach der Linie D-D der Fig.7;
• die Fig.8 und Fig.8a sowie 8b sechste Ausführungsformen einer erfindungsgemäßen Abstütz- bzw. Abstreifleiste, im Längsschnitt sowie in Schnitten nach der Linie E-E der Fig.8;
• die Fig.9 und Fig.9a eine siebente Ausführungsform einer erfindungsgemäßen Abstütz- bzw. Abstreifleiste, im Längsschnitt sowie im Schnitt nach der Linie F-F der Fig.9; und
• die Fig. 10, 10a und 10b achte Ausführungsformen einer erfindungsgemäßen Abstütz- bzw. Abstreifleiste, im Längsschnitt sowie im Schnitt nach der Linie G-G der Fig.10 bzw. im Schnitt nach der Linie H-H der Fig.10.

Show it:

• Fig.1 a device for carrying out a first method according to the invention, in a schematic representation;
• Fig.2 a device for carrying out a second method according to the invention, in a schematic representation;
• the 3 and 3a a first embodiment of a support strip or strip according to the invention, in longitudinal section and in section along the line AA Figure 3 ;
• the 4 and 4a, 4b, 4c and 4d second embodiments of a support or stripping strip according to the invention, in longitudinal section and in sections along the line BB of the Figure 4 ;
• the Fig.5 and 5a a third embodiment of a support strip or strip according to the invention, in longitudinal section and in section along the line CC of Figure 5 ;
• Figure 6 a fourth embodiment of a support or wiper strip according to the invention, in longitudinal section;
• the Fig.7 and Fig.7a, 7b and 7c Fifth embodiments of a support or stripping strip according to the invention, in longitudinal section and in the sections along the line DD of Figure 7 ;
• the Fig.8 and Fig. 8a and 8b sixth embodiments of a supporting or stripping strip according to the invention, in longitudinal section and in sections along the line EE of FIG Figure 8 ;
• the Fig.9 and Fig.9a a seventh embodiment of a supporting or stripping strip according to the invention, in longitudinal section and in section along the line FF of Figure 9 ; and
• the Fig. 10, 10a and 10b eighth embodiments of a support or stripping strip according to the invention, in longitudinal section and in section along the line GG of Figure 10 or in section along the line HH the Figure 10 ,

Based on Fig.1 a first method for controlling the temperature of a support or squeegee 1 is explained. In this case, the supporting or stripping strip 1 consists of a carrier strip 1a with ceramic elements 1b fastened thereto, wherein the supporting or stripping strip 1 is formed with two channels 11 and 12. At one end of the support or squeegee 1 close to the mouths of the two channels 11 and 12 connecting pipes 13 and 14 at. At the other end of the support or

Squeegee 1, the two channels 11 and 12 are connected to each other by means of a piece of pipe 15.
To the connecting pipe 13, the output line 23 of a mixing valve 2 is connected, which is supplied via a first connecting line 21, a carrier medium for cold and a second connecting line 22, a carrier medium for heat. By means of a control device 20, the temperature of the dispensed from the mixing valve 2 via the output line 23 carrier medium is set to that value, which temperature value that support or stripping 1 in the system should have, which is fed via the mixing valve 2 with carrier medium.

During operation of the plant for paper production, it is determined which temperature a support or stripping strip 1 located in a certain area of the installation should have. Then the mixing valve 2 is set to this temperature. As a result, this strip 1 is brought to the desired temperature by means of the supporting or stripping 1 via the output line 23 of the mixing valve 2 supplied carrier medium. The effluent from the support or squeegee 1 via the pipe 14, heated or cooled by this carrier medium is discharged via a further line 24 either in a memory or in the channel.

In the lines 23 and 24 temperature sensors 25 and 26 are further provided, by means of which the temperatures of the carrier medium flowing through these lines are detected.

By this method, the temperature of the respective support or stripping bar 1 can be brought approximately to the desired value in the rule.

According to the basis of the Fig.2 explained second method, the support or squeegee 1 is associated with a self-contained line circuit 3 for a carrier medium for heat or cold, in which a memory 30 for the carrier medium, a feed pump 4, a control valve 5, a heater 6 and a cooling device 7 are located. Furthermore, a control unit 8 is provided, which are assigned to two located in the line circuit 3 temperature sensors 81 and 82 and which serve to control the feed pump 4, the control valve 5, the heater 6 and the cooling device 7.

• Mittels der Förderpumpe 4 wird Trägermedium für Wärme oder Kälte über eine Leitung 31 zum Steuerventil 5 geleitet, von welchem es entweder über eine Leitung 32 zur Heizeinrichtung 6 oder über eine Leitung 34 zur Kühleinrichtung 7 gefördert wird. Von der Heizeinrichtung 6 bzw. von der Kühleinrichtung 7 gelangt erwärmtes bzw. abgekühltes Trägermedium über Leitungen 33 bzw. 35 und über das Anschlussrohr 13 in den Kanal 11 der Abstütz- bzw. Abstreifleiste 1 sowie über das Rohrstück 15 in den Kanal 12. Der Rückfluss des Trägermediums erfolgt über das Rohr 14 und eine Leitung 36 zur Förderpumpe 4.

The operation of this device is as follows:

• By means of the feed pump 4 carrier medium for heat or cold is passed via a line 31 to the control valve 5, from which it is conveyed either via a line 32 to the heater 6 or via a line 34 to the cooling device 7. From the heating device 6 or from the cooling device 7 is heated or cooled carrier medium via lines 33 and 35 and via the connecting tube 13 in the channel 11 of the support or squeegee 1 and via the pipe section 15 in the channel 12. The reflux The carrier medium via the tube 14 and a line 36 to the feed pump. 4

By means of the first temperature sensor 81 located in the line 35 takes place a temperature measurement of the support or stripping 1 inflowing carrier medium and by means of located in the line 36 temperature sensor 82 is a temperature measurement of the effluent from the stripping or scraper 1 medium. The measured values output by the temperature sensors 81 and 82 are transmitted via control lines 83 and 84 to the control unit 8, by means of which the feed pump 4, the control valve 5, the heating device 6 and the cooling device 7 are controlled via control lines 85, 86, 87 and 88.

Once it is determined by the control unit 8 due to the output by the temperature sensor 82 measured value that the existing in the support strip 1 temperature must be increased, the control valve 5 is redirected to the effect that the carrier medium is supplied by means of the feed pump 4 of the heater 6, in which it is heated, whereupon it is passed via the connecting pipe 13 into the channel 11. This procedure is maintained until the support or squeegee 1 has the required temperature for the particular operating case.
Soferne contrast, it is determined by the control unit 8 that the existing in the support or stripping 1 temperature must be reduced, the control valve 5 is redirected to the effect that the carrier medium is fed by means of the pump 4 of the cooling device 7, in which it is cooled , whereupon it is also passed via the connecting pipe 13 into the channel 11.
This procedure is also maintained until the support or squeegee 1 has the required temperature for the particular operating case.

A further control with regard to the heating or cooling of the supporting or stripping strip 1 can also take place in that the power of the conveying pump 4 is increased or decreased by the control unit 8.
Soferne in operation of a plant for paper production by one of the support or squeegee 1 associated control unit 8 is determined that this support or squeegee 1 has a too low or too high temperature for the relevant operating case or too rapid a change in temperature this support or stripping 1 takes place, whereby in each case there is the risk of cracking or fractures of the ceramic elements 1 b of this support or stripping 1, this support or stripping 1 is supplied according to heated or cooled support medium, whereby the ceramic Elements 1b are not exposed to unacceptable thermal loads, thereby preventing damage caused thereby.

By means of this second method, a largely accurate control of the temperature of the respective support or wiper strip takes place, independently of the particular operating circumstances.

In the 3 and 3a . 4 and 4a to 4d . 5 and 5a, Fig.6 . Fig.7 and 7a to 7c . 8 and 8a, 8b . Fig.9 and 9a . Fig. 10, 10a and 10b Several embodiments of support or squeegee 1 are shown, which consist of support strips 1a with attached to these plates 1b made of ceramic material and which are formed with channels 11 and 12, which enforce this support or squeegee 1 in the longitudinal direction. These channels can begin at one end of the support or squeegee 1 and end at the other end of the strips 1. Alternatively, these channels may begin at one end of the squeegee 1 and be returned to that end. Furthermore, these channels can pass through the ceramic plates 1 b or be provided in the support bar 1 a or be located between the ceramic plates 1 b and the support bar 1 a. Furthermore, the channels may be formed with different cross sections.

Since the plates 1 b of ceramic material have a very low thermal conductivity, the arrangement of the channels within the support or squeegee or the formation of the cross section is of crucial importance to ensure that the targeted by the carrier medium flowing through this Temperature of the plates 1 b made of ceramic material is achieved in order to avoid their damage by thermal stresses.
As a carrier medium for cold or for heat in particular water is used.

Claims (25)

1. A method of controlling the temperature of the ceramic elements (1b) of a supporting or scraper bar (1), which is associated in a papermaking installation with the at least one screen belt or at least one felt belt located therein, characterised in that the supporting or scraper bar (1) is constructed with at least one channel (11, 12), through which a carrier medium for heat or cold is passed.
2. A method according to claim 1, characterised in that a mixing valve (2) is provided in the line leading to the at least one channel (11, 12), to which mixing valve (2) lines (21, 22) for carrier media for heat or cold are connected and which is set to the temperature which the relevant supporting or scraper bar (1) is intended to exhibit.
3. A method according to either one of claims 1 and 2, characterised in that a temperature sensor (15) is provided in the line (26) leading away from the supporting or scraper bar (1), which temperature sensor (15) measures the temperature of the carrier medium flowing away from the supporting or scraper bar (1).
4. A method according to any one of claims 1 to 3, characterised in that a temperature sensor (25) is provided in the line (23) leading towards the supporting or scraper bar (1), which temperature sensor (25) measures the temperature of the carrier medium flowing towards the supporting or scraper bar (1).
5. A method according to claim 1, characterised in that the temperature of the carrier medium flowing to the supporting or scraper bar (1) is controlled as a function of the temperature of the carrier medium flowing away therefrom.
6. A method according to claim 5, characterised in that the carrier medium is conveyed by means of a feed pump (4) in a continuous line circuit (3).
7. A method according to either one of claims 5 and 6, characterised in that the carrier medium flowing away from the supporting or scraper bar (1) passes either through a heating device (6) or through a cooling device (7) and is then fed to the supporting or scraper bar (1).
8. A method according to claim 7, characterised in that the heating device (6) or the cooling device (7) is controlled as a function of the temperature of the carrier medium flowing away from the supporting or scraper bar (1).
9. A method according to claim 7, characterised in that the output of the feed pump (4) is controlled as a function of the temperature of the carrier medium flowing away from the supporting or scraper bar (1).
10. A method according to claim 7, characterised in that the outputs of the heating device (6) or the cooling device (7) and the output of the feed pump (4) are controlled as a function of the temperature of the carrier medium flowing away from the supporting or scraper bar (1).
11. A method according to any one of claims 1 to 10, characterised in that the carrier medium is passed continuously through the supporting or scraper bar (1).
12. A method according to any one of claims 1 to 11, characterised in that the carrier medium is passed continuously through the ceramic elements (1b) of the supporting or scraper bar (1).
13. An installation for carrying out the method according to any one of claims 1 to 12, characterised in that the supporting or scraper bar (1) is constructed with at least one channel (11, 12), to which are connected a line (13) for carrier medium flowing towards the supporting or scraper bar (1) and a line (14) for carrier medium flowing away therefrom.
14. An installation according to claim 13, characterised in that a mixing valve (2) for carrier media for heat and cold is located in the line (23) leading to the at least one channel (11, 12).
15. An installation according to claim 14, characterised in that a temperature sensor (25, 26) is located in the line (23) leading towards the supporting or scraper bar (1) and/or in the line (24) leading away therefrom.
16. An installation according to claim 13, characterised in that a line system (3) is provided, in which there are located a feed pump (4) for the carrier medium and a heating device (6) and a cooling device (7) for the carrier medium and in that in addition there are provided at least one temperature sensor (82) for determining the temperature of the carrier medium flowing away from the supporting or scraper bar (1) and a control unit (8) for controlling the outputs of the heating device (6) and the cooling device (7) and/or the feed pump (4).
17. An installation according to claim 16, characterised in that at least one temperature sensor (81) for determining the temperature of the carrier medium fed to the supporting or scraper bar (1) is also provided.
18. A supporting or scraper bar (1) for carrying out the method according to any one of claims 1 to 12 or for an installation according to any one of claims 13 to 17, characterised in that it is constructed with at least one channel (11, 12) for conveying a carrier medium for heat or cold.
19. A supporting or scraper bar (1) according to claim 18, characterised in that the channel (11) passes through the ceramic elements (1b).
20. A supporting or scraper bar (1) according to claim 18, characterised in that the channel is located between the ceramic elements (1b) and a carrier bar (la) for the ceramic elements (1b).
21. A supporting or scraper bar (1) according to any one of claims 18 to 20, characterised in that the channel starts at one end of the supporting or scraper bar (1) and ends at the other end thereof.
22. A supporting or scraper bar (1) according to any one of claims 18 to 20, characterised in that the channel starts at one end of the supporting or scraper bar (1) and is returned therein to the same end.
23. A supporting or scraper bar (1) according to claim 22, characterised in that the outward channel (11) is connected to the return channel (12) within the supporting or scraper bar (1).
24. A supporting or scraper bar (1) according to claim 22, characterised in that the outward channel (11) is connected to the return channel (12) by means of a pipe piece (15) located outside the supporting or scraper bar (1).
25. A supporting or scraper bar according to any one of claims 18 to 24, characterised in that both the ceramic elements (1b) and the carrier bar (1a) are constructed with at least one channel or with channel pieces.

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