WO2010025999A1

WO2010025999A1 - Heating system for treating a fibrous material web

Info

Publication number: WO2010025999A1
Application number: PCT/EP2009/059703
Authority: WO
Inventors: Martin Dauner
Original assignee: Voith Patent Gmbh
Priority date: 2008-09-08
Filing date: 2009-07-28
Publication date: 2010-03-11
Also published as: CN102149871A; EP2329077A1; DE102008041860A1

Abstract

Means (72, 74) are provided in a heating system for treating a fibrous material web, particularly a paper, cardboard, or tissue web, comprising one or more heating groups, each having one or more heating levels (54-58), which include one or more drying cylinders (60-66, 80) heated by steam, in order to compress the residual exhaust vapor remaining after the last heating level or group of the heating system as viewed in the flow direction of the steam, and to return the same to the heating system.

Description

Heating system for treating a fibrous web

The invention relates to a heating system for treating a fibrous web, in particular paper, board or tissue web, with one or more heating groups, each comprising one or more heating stages, each containing one or more steam-heated drying cylinders. It also relates to a machine for producing and / or treating a fibrous web, in particular paper, board or tissue web, with one or more dry sections, each of which comprises one or more such heating systems.

One or more heating systems of this kind may for example be associated with the dryer section of a paper and / or coater. 1 shows a schematic representation of the first heating group 10 of a conventional heating system viewed in the web running direction L. In this case, the broth steam 12 from the second heating stage or group 14, viewed in the direction of web travel L, is directed to the first heating group 10 at a lower pressure level, which is associated with or arranged downstream of the latter in the vapor flow direction F. Mixture with live steam 18 produces mixed steam (heating steam) 20, which is used to heat the drying cylinder (s) 22-30 of the first heating group 10 viewed in the web running direction L. After this considered in the web running direction L first heating group 10, which is the last group in the heating system, the Restbrüdendampf 33 from one of the first heating group 10 associated or downstream separator 32 is passed into a vapor condenser 34 and with cooling water. completely condensed. The condensate is subsequently returned to the separator 32 assigned to the first heating group 10.

As can be seen from FIG. 1, steam and condensate from the second heating group 14 are fed to the separator 16 assigned or connected downstream of the second heating group 14. Condensate from the two separators 16 and 32 is discharged into a condensate collection tank. The first heating group 10 associated or downstream separator 32 is supplied via a line 38, steam, condensate and air, for example, leakage air to flanges. The residual vapor 33 coming from the separator 32 and supplied to the vapor condenser 34 may contain an air / vapor mixture. The drying cylinders 22 - 28 are acted upon by control valves 42 with pneumatic control with mixed steam 20, which are each controlled via a pressure regulator 44. Between the vapor condenser 34 and the separator 32, an air separator 40 is provided. A pressure control valve 48 with pneumatic control, which can be controlled again via a pressure regulator 46, serves to set the operating parameter of a vacuum pump 50, wherein the operating parameter may be, for example, the pressure Pv. Alternatively, a speed control can be provided. In the separator 32 there is no stratification air / steam, since no air is sucked out.

A disadvantage of such known heating systems is that the residual steam is no longer used. The energy contained therein is transferred in the vapor condenser 34 to the cooling water 36 and is thus lost. Heat energy in the steam is no longer used economically. This results in a relatively high consumption of cooling water. The invention has for its object to provide an improved heating system of the type mentioned, in which the heat energy in the residual steam used economically and correspondingly less live steam is needed.

This object is achieved in that means are provided to compress the Restbrüdendampf, which remains after the last viewed in the flow direction of the steam last heating stage or group of the heating system, and returned to the heating system.

Due to this training primary energy is saved in the heating of the drying cylinder. The heat energy in the residual steam is used economically in an optimal way, so that less live steam is needed. The energy costs are thus significantly reduced overall. In addition, the cooling water consumption is reduced.

The residual vapor is expediently removed from one of the last heating stage or group assigned or downstream separator.

According to a preferred practical embodiment of the heating system according to the invention, a steam jet pump is provided for compressing the residual steam, the residual steam in the steam jet pump preferably being compressed with live steam.

To compress the residual steam, a mechanical compressor may alternatively be provided in particular.

Preferably, the drying cylinder (s) of the last heating stage or group can be heated with mixed steam, the residual broth steam passing through Compression is compressed to the pressure of the mixture vapor and assigned to this.

It is advantageously possible to supply missing live steam via a live steam line.

According to a further preferred practical embodiment, vacuum pumps are provided for discharging non-condensable gases which penetrate into the heating system under vacuum from the separator assigned to the last heating stage.

In a practical embodiment of the heating system according to the invention, the temperature of the drying cylinder generally increases in the web running direction.

Conveniently, the heating system is in particular also designed so that in each heating stage of a heating group pressure is reduced and according to the flow direction of the heating steam is opposite to the web running direction. This applies in particular to heating groups connected in series.

The heating system can advantageously be designed so that steam of a respective heating group or stage is completely recirculated in the manner of a thermocompressor system.

According to an advantageous alternative embodiment, the heating system is designed such that, in the manner of a cascade system, steam of a respective preceding heating group or stage is used in a respective subsequent heating group or stage. The vapor pressure level of a subsequent heating group or stage is lower than that of respective preceding heating group or stage. Depending on the desired vapor pressure or temperature profile along a drying section, these heating groups or stages do not necessarily have to be next to each other spatially. The heating steam can be passed, for example, from the fourth heating group directly into the first heating group. This may be useful in this example if the temperature in the second and third heating group is higher than that in the fourth heating group and the temperature of the first heating group is lower than that in the fourth heating group.

Means are preferably provided to produce by mixing the Brüdendampfes from the penultimate heating stage or group of the heating system with live steam mixture steam (heating steam) for heating the last heating stage or group.

The machine according to the invention for producing and / or treating a fibrous web, in particular a paper, board or tissue web, is characterized in that it comprises one or more dry sections, each comprising one or more heating systems according to the invention.

Preferably, at least one drying section is provided, each with only one heating system according to the invention. In particular, all dry sections can each have only one such heating system according to the invention.

According to a further advantageous embodiment of the machine according to the invention, at least one drying section is provided with a plurality of independent heating systems according to the invention. It is thus possible for the residual-charge steam, which remains after the first heating stage or group at the beginning of the respective drying section in the drying process, to be compressed by means of, for example, a jet pump or a mechanical compressor and fed back into the system, whereby its thermal energy is utilized. which leads to the reduction of the live steam demand. The residual vapor can be compressed by compression to the pressure of the mixture vapor. About the main steam line, the missing live steam can be supplied. The non-condensable gases which penetrate into the system under vacuum can be continuously removed from the separator assigned to the first heating stage or arranged downstream by means of the vacuum pumps.

Due to the reuse of the residual steam, less or even no longer cooling is required during operation, which reduces the cooling water requirement.

The heating system according to the invention and the machine according to the invention thus bring, inter alia, the advantage that the consumption of live steam is reduced by the use of the residual steam of the family, which entails a corresponding reduction of the energy costs. In addition, the cooling water consumption is reduced.

The invention can be used, for example, in the dry sections of a paper and / or coater, which can comprise, for example, a pre-blank section, a surface finishing station comprising, for example, a size press and / or a coater, a post-dryer section, a coater, and a further after-dryer section. The invention is applicable, for example, to a thermocompressor system or to a cascade system. The heating system is used Heating the drying cylinders with steam. It may comprise one or more heating groups, each of which may have one or more heating stages. A respective heating stage may comprise one or more drying cylinders. A drying section, for example pre-drying section or after-dryer section, may comprise one or more heating systems according to the invention. Preferably, the dry sections each comprise exactly one heating system according to the invention. The temperature of the drying cylinder increases substantially in the web running direction. Consequently, the flow direction of the heating steam is opposite to the web running direction, since pressure is reduced in each heating stage.

In particular, the following two types of heating systems are conceivable, to which the invention can be advantageously applied:

- Thermocompressor system in which the steam of a heating group or

completely recirculated,

Cascade system in which steam of a heating group or stage is used in the next heating group or stage.

The invention will be explained in more detail below with reference to exemplary embodiments with reference to the drawing; in this show:

Fig. 1 is a simplified schematic representation of in

Web running direction regards first heating group of a conventional heating system,

Fig. 2 is a simplified schematic representation of in

Web running direction regards first heating group of an exemplary embodiment of the heating system according to the invention, Fig. 3 is a simplified schematic representation of in

Web running direction regards first heating group of an exemplary embodiment of the invention applied to a thermal compressor system

heating system

Fig. 4 is a simplified schematic representation of in

Web running direction regards first heating group of an exemplary embodiment of the invention applied to a cascade heating system according to the invention and

5 shows a simplified schematic representation of a paper and / or coating machine with a pre-drying section, a surface finishing station comprising, for example, a size press and / or a coating unit, a post-dryer section, a coating unit and a further after-dryer section.

2 shows, in a simplified schematic representation, the first heating group 52, viewed in the web running direction L, of an exemplary embodiment of the heating system according to the invention. The heating system is used for example for the treatment of a fibrous web, in particular paper, board or tissue web and comprises one or more heating groups, each comprising one or more heating stages, each containing one or more steam-heated drying cylinders.

As can be seen with reference to FIG. 2, the first heating group 52 comprises, for example, three heating stages 54-58. The first two comprise the first Heating stages 54, 56, for example, only one drying cylinder 60 and 62, while the third heating stage 58 in the present case, for example, two drying cylinders 64 and 66 includes.

Means are provided for compressing the residual vapor steam 68 remaining after the last heating stage or group 52 of the heating system, viewed in the flow direction F of the steam or heating steam, and returning it to the heating system.

The residual vapor steam 68 is removed from one of the last heating stage or group 52 associated or downstream separator 70.

For example, a steam jet pump 72 may be provided for the thermal compression of the residual vapor steam 68. In this case, the residual steam 78 can be compressed in the steam jet pump 72, in particular with live steam. However, for example, a mechanical compressor 74 may also be provided for compressing the residual-charge steam 68.

The drying cylinder (s) 60 - 66 of the last heating stage or group 52 can be heated with mixed steam 76. The residual vapor steam 68 can be compressed by compression to the pressure of the mixture vapor 76 and supplied thereto.

The Restbrüdendampf (68) can also by compression on the

Compressed pressure of the mixture vapor in the respective supply lines to the heating stages 56 and / or 54 are compressed and fed only this or in addition. Non-condensable gases entering the vacuum heating system can optionally be removed via one or more vacuum pumps 78 from the separator 70 assigned to the last heating stage or group 52.

As can be seen in particular from FIG. 5, the temperature of the drying cylinders 60 - 66, 80 in the web running direction L can generally increase.

Since pressure is released in each heating stage 54-58 (compare also FIG. 5) of a heating group, the flow direction F of the heating steam is correspondingly opposite to the web running direction L in series heating groups.

As can be seen from FIG. 2, an air / vapor mixture stratification results in the separator 70. Condensate from the separator 70 is fed to a condensate collector 84.

On the right side of Fig. 2, the remaining in the first heating group 52 in the other elements are further specified.

The required extraction of air may, for example, take place to a condenser 86 and / or via a line 88 leading to the vacuum pump or pumps 78. Between the condenser 86 and the separator 70, an air separator 87 may be provided.

FIG. 3 shows, in a simplified schematic representation, a first heating group 52, viewed in the direction of web travel L, of a comparable exemplary embodiment of the thermal compressor system. used inventive heating system in which steam of a heating group is fully recirculated.

In the present case, too, this first heating group 52 again comprises, for example, three heating stages 54-58. To compress the residual-boiling steam 68 from the separator 70, a steam jet pump 72 or a mechanical compressor 74 can again be provided.

The required air extraction can, for example, be made again to the condenser 86 and / or via the line 88 leading to the vacuum pump or pumps 78. Between the condenser 86 and the separator 70, an air separator 87 may again be provided.

On the right side of FIG. 3, the elements still contained in the last heating group 52 are again denoted in more detail.

FIG. 4 shows, in a simplified schematic representation, the first heating group 52, viewed in the web running direction L, of a comparable exemplary embodiment of the heating system applied to a cascade system according to the invention. In the present case, for example, the first heating group 52 again comprises three heating stages 54-58. In order to compress the residual-boiling steam 68 from the separator 70, a steam-jet pump 72 or a mechanical compressor 74 can again be provided in the present case.

The required air extraction, for example, again to a condenser 86 and / or via a line 88, which leads to the one or more vacuum pumps 78. Between the condenser 86 and the separator 70, an air separator 87 may again be provided. On the right side of Fig. 4, the remaining in the first heating group 52 in the other elements are further specified.

Also in the two embodiments according to FIGS. 3 and 4, the residual-charge steam 68 can in each case be compressed again by compression to the pressure of the mixed steam 76 and supplied thereto.

However, the residual-charge steam 68 can also be compressed by compression to the pressure of the mixture steam in the respective supply lines to the heating stages 56 and / or 54 and supplied thereto only or additionally thereto.

The pressure values contained in the figures as well as the respective number of heating stages and drying cylinders within the first heating group 52 are purely exemplary.

FIG. 5 shows, in a simplified schematic representation, a paper and / or coater 90 with a pre-drying section 92, as seen in the web running direction L, a surface finishing station 94, for example a size press and / or a coater, a post-dryer section 96, a coater 98 and another night dryer section 100.

As can be seen from FIG. 5, the pre-drying section 92 comprises, for example, four heating groups, the after-dryer section 96, for example two heating groups, and the further after-drying section 100, for example a heating group. For example, the first heating group (heating group 1) can have three heating stages (HS1 .1-HS1.3), the second heating group (heating group 2) can have two heating levels (HS2.1, HS2.2), the third heating level group (heating group 3), for example, two heating levels (HS3.1, HS3.2), the fourth heating group (heating group 4), for example, a heating level (HS4.1), the night dryer section 96 associated fifth heating group (heating group 5), for example, three heating levels (HS5 .1 - HS5.3), the sixth heating group (heating group 6) also assigned to the after-dryer section 96, for example two heating stages (HS6.1, HS6.2) and the seventh heating group (heating group 7) assigned to the further after-dryer section 100, for example three heating stages (HS7.1 - HS7.3). In this case, one or more of the drying sections formed by the pre-drying section 92 and the after-drying sections 96, 100 can each be assigned one or more heating systems according to the invention, the respective drying sections preferably being provided in each case only with such a heating system according to the invention. For example, it is also possible to provide at least one drying section with a plurality of independent heating systems according to the invention.

As can be seen from the middle part of FIG. 5, the vapor pressure in the pre-drying section 92 in the web running direction L initially rises generally from the first drying stage HS1 .1 to the next-to-last drying stage HS3.2, whereas it starts from the penultimate drying stage HS3. 2 until the last dry stage HS4.1 falls again slightly. In the case of a cascade system of the heating group 4, the heating group 1 is followed by a lower pressure and temperature level. In the after-dryer section 96, the vapor pressure generally increases from the first drying stage HS5.1 to the last drying stage HS6.2. The same applies to the vapor pressure curve in the after-dryer section 100.

As can be seen from the lower part of FIG. 5, the dry content of the paper web within a respective drying section decreases from 92 to 100 the first drying stage continuously up to the last drying stage.

In FIG. 5, the drying cylinders are each designated 80.

LIST OF REFERENCE NUMBERS

10 first heating group

12 brothers steam

14 second heating group

16 separators

18 live steam,

20 mixture steam, heating steam

22 drying cylinders

24 drying cylinders

26 drying cylinders

28 drying cylinders

30 drying cylinders

32 separators

33 residual steam

34 vapor condenser

36 cooling water

38 line

40 air separators

42 control valve

44 pressure regulator

46 pressure regulator

48 control valve

50 vacuum pump

52 first heating group

54 heating level

56 heating level

58 heating level

60 drying cylinders

62 drying cylinders 64 drying cylinders

66 drying cylinders

68 residual steam

70 separators

72 steam jet pump

74 mechanical compressor

76 mixed steam

78 vacuum pump

80 drying cylinders

84 condensate collector

86 capacitor

87 air separator

88 line

90 paper and / or coating machine

92 pre-drying section

94 surface finishing station

96 night drying section

98 coating unit

100 night drying section

F flow direction of the heating steam bzv

L Bahnlaufrichtune

Claims

claims

A heating system for treating a fibrous web, in particular paper, board or tissue web, having one or more heating groups, each comprising one or more heating stages (54-58) each having one or more steam-heated drying cylinders (60-66, 80), in that I mean that means (72, 74) are provided for determining the residual vapor (68), the last heating stage or group (54, 52) of the last heating stage or group, as viewed in the flow direction (F) of the steam Heating system remains to compress and due to the heating system.

2. Heating system according to claim 1, characterized geke nnze ichne t that the residual steam (68) from one of the last heating stage or group (54 bzw.52) associated or downstream separator

(70) is discharged.

3. Heating system according to claim 1 or 2, characterized geke nnze ichne t that for compressing the Restbrüdendampfes (68) a steam jet pump (72) is provided, wherein the residual steam in the vapor jet steam pump is preferably compressed with live steam.

4. Heating system according to one of the preceding claims, characterized geke dnze tne that for compressing the residual steam (68) a mechanical compressor (74) is provided.

5. Heating system according to one of the preceding claims, characterized geke nnze ichne t that the drying cylinders or the (60-66, 80) of the last heating stage or group (54 bzw.52) are heated with mixed steam (76) and that the Restbrüdendampf (68) by compression on the

Pressure of the mixture vapor (76) is compressed and supplied to this.

6. Heating system according to claim 5, characterized geke nnze ichne t that missing live steam can be supplied via a main steam line.

A heating system according to any one of the preceding claims, characterized in that one or more vacuum pumps (78) are provided for introducing non-condensable gases entering the under vacuum heating system from the last heating stage or group (54 and 52 respectively) ) assigned or downstream separator (78) lead off.

8. Heating system according to one of the preceding claims, characterized in that the temperature of the drying cylinders (60-66, 80) in the web running direction (L) generally increases.

9. Heating system according to one of the preceding claims, characterized geke nnze ichne t that in each heating stage (54-58) of a heating group pressure is reduced and according to the flow direction (F) of the heating steam to

Web running direction (L) is opposite.

10. Heating system according to one of the preceding claims, characterized geke dnze tan that in the manner of a thermocompressor system steam of a respective heating group or stage (54 bzw.52) is completely recirculated in this.

A heating system according to any one of the preceding claims, characterized in that steam of a respective preceding heating group or stage is used in a respective subsequent heating group or stage in the manner of a cascade system.

12. Heating system according to one of the preceding claims, characterized geke nnze ichne t that means are provided to mix by mixing the Brüdendampfes from the penultimate heating stage or group of the heating system with steam fresh steam mixture for heating the last heating stage or group (54 bzw. 52).

13. Machine for producing and / or treating a fibrous web, in particular paper, board or tissue web, with one or more drying section (92-100), each one or more Heating systems according to one of the preceding claims.

14. Machine according to claim 13, characterized in that at least one drying section (92-100) is provided, each with only one heating system according to one of claims 1 to 12.

A machine according to claim 13 or 14, characterized in that at least one drying section (92-100) is provided with a plurality of independent heating systems according to any one of claims 1 to 12.