EP3339507A1 - Heating group subsystem and method for operating a heating group subsystem - Google Patents

Abstract

The invention relates to a method for operating a heating group subsystem (1) of a machine for producing or treating a fibrous web, in particular a paper or board web, wherein the heating group subsystem (1) has a first heating group (HG1) and a last heating group (HG3) and at least a further heating group (HG2) with in each case at least one device (1.1, 1.2, 1.3, 1.4, 2.1, 2.2, 3.1.3.2) heated with a steam pressure, in particular a drying cylinder, for heating the fibrous web, wherein the fibrous web in Direction of the machine seen first through the first heating group (HG1), then through the at least one further heating group (HG2) and then through the last heating group (HG3) is performed.

According to the invention, it is provided that the vapor pressure of the heating steam of the at least one further heating group (HG2) is set lower than the respective vapor pressure of the heating steam of the first heating group (HG1) and the last heating group (HG3).

Description

The invention relates to a method for operating a Heizgruppenteilsystems a machine for producing or treating a fibrous web, in particular a paper or board web, said Heizgruppenteilsystem a first heating group and a last heating group and at least one further heating group, each having at least one having a vapor pressure Heating steam heated device, in particular a drying cylinder, for heating the fibrous web comprises, wherein the fibrous web is guided in the machine direction of the machine successively through the heating groups.
The invention also relates to a heating group subsystem of a machine for producing or treating a fibrous web, in particular a paper or board web.

Methods and heating systems of this type are known. The document WO 2014/180645 A1 discloses a cascade steam system for a dryer section of a paper machine in which the vapor pressure of the heating steam in the first heating group is higher than in the second heating group and higher than the vapor pressure in the third heating group. The heating system is arranged so that the vapor pressure of the heating groups in the machine direction increases. To reduce the energy consumption, a thermocompressor is provided, which increases the pressure of the vapor of the last heating group so that it can be supplied to the heating group system again as heating steam.

The document AT384254 B also describes a cascade steam system for a dryer section of a paper machine in which the vapor pressure of the heating steam in the first heating group is higher than in the second heating group and higher than the vapor pressure in the third heating group. The heating group system is arranged so that the vapor pressure of the heating groups in the machine direction increases. The vapor of the heating group with the lowest pressure level is deposited in a heat exchanger for heating the engine air and an auxiliary condenser.

The object of the invention is to propose a heating system with improved energy efficiency and more flexible operation, as well as reduced energy consumption for paper drying.

The object is solved by the features of method claim 1. The invention relates to a method for operating a heating group subsystem of a machine for producing or treating a fibrous web, in particular a paper or board web, wherein the heating group subsystem comprises a first heating group and a last heating group and at least one further heating group each having at least one with a vapor pressure Heating steam heated device, in particular a drying cylinder, for heating the fibrous web comprises, wherein the fibrous web is seen in the machine direction, first by the first heating group, then passed through the at least one further heating group and then through the last heating group. According to the invention, the vapor pressure of the heating steam of the at least one further heating group is set lower than the respective vapor pressure of the heating steam of the first heating group and the last heating group.

The object is also achieved by the independent device claim 7. A heating group subsystem of a machine for producing or treating a fibrous web, in particular a paper or board web, is proposed, wherein the heating group subsystem comprises a first heating group and a last heating group and at least one further heating group, each with at least one heating device having a steam pressure, in particular a drying cylinder, for heating the fibrous web comprises, wherein the fibrous web seen in the machine direction, first by the first heating group, then passed through the at least one further heating group and then through the last heating group. According to the invention, the vapor pressure of the heating steam of the at least one further heating group is lower than the respective vapor pressure of the heating steam of the first heating group and the last heating group.

The heating group subsystem preferably forms part of the overall heating system of a machine for producing or treating a fibrous web, in particular a paper or board web. Seen in the machine direction, therefore, further heating groups can be arranged after the heating group subsystem.

The heating group subsystem is advantageously used in a paper machine for drying the fibrous web in a dryer section. In some cases, for example, when the fibrous web is painted or glued, the dryer section is divided into a pre-dryer section and a post-dryer section. It is possible that that Heizgruppenteilsystem is used in the pre-dryer section and / or in the after-dryer section.

In a practical case, the heating group subsystem is arranged so that the first heating group of the heating group subsystem is the first heating group in the running direction of the machine. The Heizgruppenteilsystem is thus arranged at the beginning of the dryer section. The first heating group thus supplies the first or the first plurality of devices heated with a steam pressure having heating steam. This can also be applied correspondingly to a pre-drying section and / or a post-drying section. The vapor pressure of the heating steam of the at least one further heating group is, in contrast to the known state of the art of the cascade heating systems, lower than the vapor pressure of the first heating group. The at least one further heating group is arranged between the first heating group and the last heating group.

The heating group subsystem according to the invention preferably has three heating groups. The at least one further heating group forms in this case the second heating group seen in the direction of the machine.

It is also conceivable that the heating group subsystem according to the invention comprises four heating groups. So there are two more heating groups provided which form the second and the third heating group in this case. The vapor pressure of the heating steam of the two further heating groups is in each case lower than the respective vapor pressure of the heating steam of the first heating group and the last heating group.

Furthermore, it is also possible for the heating group subsystem according to the invention to have more than four heating groups. So there are provided according to more than two more heating groups. The vapor pressure of the heating steam of the other heating groups is lower than the respective vapor pressure of the heating steam of the first heating group and the last heating group.

In the production operation of the machine, all vapors accumulating in the heating groups of the heating group subsystem in this solution according to the invention are returned to specific steam supply lines for the heating groups and thus supplied to the corresponding heating steam for drying the fibrous web. Thus, all vapors, without condense them, reused directly for paper drying.

In a practical case, the vapor pressure of the heating steam of the first heating group is set equal to or higher than the vapor pressure of the heating steam of the last heating group. For the second case, the vapor pressure of the heating steam of the first heating group is thus the highest steam vapor pressure in the heating group subsystem. When viewed in the running direction of the machine, the fibrous web is exposed to high temperature at the beginning of the dryer section and is heated strongly.

In an advantageous embodiment, the vapor pressure of the heating steam of the at least one further heating group is set in the range between 50 kPa and 700 kPa above the ambient pressure, preferably between 50 kPa and 400 kPa. Conveniently, the vapor pressure of the heating steam of the first heating group is in the range between 200 kPa and 1000 kPa above the ambient pressure and the vapor pressure of the heating steam of the last heating group in the range between 300 kPa and 900 kPa above ambient pressure.

In a practical embodiment, the heating steam, after flowing through the respective steam-heated device, is fed to a heating group in each case to a separator for separating condensate and vapor. The broth steam of the first heating group and the broth steam of the at least one further heating group and the broth steam of the last heating group are fed to the heating steam of the steam-heated device at least one of the at least one further heating group.

Preferably, the vapor vapor of the at least one further heating group is fed via a thermocompressor to the heating steam of the steam-heated device of at least one of the at least one further heating group. The thermocompressor is preferably supplied with live steam of a steam supply system, wherein the vapor pressure of the live steam is higher than the vapor pressure of the heating steam of the heating groups.

Conveniently, the heating group subsystem, seen in the direction of the machine comprising a dryer section, is provided at the beginning of a dryer section of a paper machine.

The vapor pressure of the heating steam of the first heating group is set equal to or higher than the vapor pressure of the heating steam of the last heating group.

The respective heating group and thus the respective at least one device heated with heating steam is connected via a steam supply line to a steam supply line. Each heating group is assigned a separator for the separation of condensate and Brüdendampf. The respective separator is connected in each case via a discharge line with the respective heating group and the respective steam-heated device. The separator of the first heating group and the separator of the at least one further heating group and the separator of the last heating group are each connected via a vapor line to the steam supply line of the at least one further heating group.

The steam supply line is preferably connected to a steam supply system whose vapor pressure is higher than the vapor pressure of the heating steam of the heating groups.

In a practical embodiment, the vapor line for the vapor from the separator of the at least one further heating group for compression via a thermocompressor to the steam supply line is connected, wherein the thermocompressor is preferably connected to the steam supply line.

Furthermore, it is advantageous if the respective condensate line of the separator of the first heating group and of the separator of the last heating group is connected to the discharge line of one of the at least one further heating group.

According to a further advantageous development, the vapor line of the first heating group has a backflow prevention device, for example a non-return valve. This is advantageous when the Heizgruppenteilsystem, for example, in the production of certain types of paper, operated as a cascade heating system, in which case, as seen in the machine direction, the first heating group of the heating group subsystem has the lowest vapor pressure of the heating steam of all heating groups of Heizgrouppenteilsystems and the at least one further heating group of the heating group subsystem has the second lowest vapor pressure. This design of the heating system is a flexible mode of operation for the achieved different requirements in the production of different fibrous webs on one machine. The backflow prevention device prevents the heating steam of the at least one further heating group from flowing back into the separator of the first heating group via the vapor line.

In a further embodiment, a vacuum separator for generating or providing vapors of condensate in the vacuum region is provided, which is connected via a vapor line with a thermocompressor, wherein the vapor of the vacuum separator is compressed by the thermocompressor and the steam supply line of the first heating group is supplied. This is advantageous if the Heizgruppenteilsystem, for example, in the production of certain types of paper to be operated as a cascade heating system. This design of the heating system achieves energy-efficient and flexible operation with low energy consumption for the different requirements in the production of different fibrous webs on one machine. By this configuration, condensate can be converted from the process into steam and fed to the paper drying process.

It is also possible to provide further heating groups between the first heating group HG1 and the last heating group HG3, wherein these further heating groups also have a vapor pressure which is less than the vapor pressure of the first heating group and which is less than the vapor pressure of the last, ie in this Example of the third heating group is. The condensate lines and vapor lines can then be connected to the steam supply lines or the discharge lines of one of the at least one further heating group or the second heating group in accordance with the heating group subsystem according to the invention.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the drawings.

Figur 1a

eine schematische Darstellung eines Heizgruppenteilsystems nach dem Stand der Technik;

Figur 1b

den Dampfdruck des Heizdampfes der einzelnen Heizgruppen nach dem Stand der Technik

Figur 2a

eine beispielhafte Ausführungsform eines erfindungsgemäßen Heizgruppenteilsystems in schematischer und vereinfachter Darstellung;

Figur 2b

den Dampfdruck des Heizdampfes der einzelnen Heizgruppen eines erfindungsgemäßen Heizgruppenteilsystems

Figur 3

ein praktisches Ausführungsbeispiel eines erfindungsgemäßen Heizgruppenteilsystems

Show it

FIG. 1a

a schematic representation of a heating group subsystem according to the prior art;

FIG. 1b

the vapor pressure of the heating steam of the individual heating groups according to the prior art

FIG. 2a

an exemplary embodiment of a Heizgruppenteilsystems invention in a schematic and simplified representation;

FIG. 2b

the vapor pressure of the heating steam of the individual heating groups of a heating subset according to the invention

FIG. 3

a practical embodiment of a Heizgruppenteilsystems invention

The FIG. 1a shows a schematic representation of a heating group subsystem for a dryer section of a paper machine with drying cylinders according to the prior art, which is designed as a cascade heating system consisting of 3 heating groups HG1, HG2, HG3. The heating groups are heated with heating steam. The steam supply pipes 3, 4, 5 are connected to a steam supply pipe 2. The steam supply lines 2 are supplied by a steam supply system DV with heating steam. The heating groups HG1, HG2, HG3 are arranged successively with respect to the running direction of the paper machine. The heating group HG1 thus forms the first heating group and supplies the first drying cylinders with heating steam. The steam supply line 2 also supplies an after-drying section NTP with steam. The amount of heating steam for each heating group is adjustable by valves. After the heating steam of a heating group HG1, HG2, HG3 has passed through the drying cylinders, the mixture of saturated steam and condensate is fed via the discharge lines 6, 7, 8 to a respective separator S1, S2, S3 for the separation of the broth steam and condensate. In the condensate lines 9, 10, 11, the respective condensate is discharged. The Brüdendampf the heating group HG3 is supplied from the separator 3 via the vapor line 14 of the steam supply line 4 of the second heating group HG2. Accordingly, the Brüdendampf the heating group HG2 is supplied from the separator 2 via the vapor line 13 of the steam supply line 3 of the first heating group HG1. By contrast, the Brüdendampf the heating group HG1 is supplied from the separator 1 via the vapor line 12 a capacitor KS and condensed there. The latent heat of the Brüdendampfes the heating group HG1 is therefore not used directly for paper drying. Like in the FIG. 1b is shown, the vapor pressure PD of the heating steam in the heating groups HG1, HG2, HG3 are selected such that the first heating group HG1 has the lowest vapor pressure PD, the second heating group HG2 has the second lowest vapor pressure PD, and the third heating group HG3 has the highest vapor pressure PD.

The FIG. 2a shows an exemplary embodiment of a heating group subsystem according to the invention in a schematic and simplified representation for a dryer section of a paper machine with drying cylinders, comprising 3 heating groups HG1, HG2, HG3. The heating groups are heated with heating steam. The steam supply pipes 3, 4, 5 are connected to a steam supply pipe 2. The steam supply lines 2 are supplied by a steam supply system DV with heating steam. The heating groups HG1, HG2, HG3 are arranged successively with respect to the running direction of the paper machine. The heating group HG1 thus forms the first heating group and supplies one or more first drying cylinders with heating steam. The steam supply line 2 also supplies an after-drying section NTP with steam. The vapor pressure of the respective heating steam can be set independently for each heating group HG1, HG2, HG3 by means of valves. After the heating steam of a heating group HG1, HG2, HG3 has flowed through the drying cylinder or the cylinder, the mixture of broth steam and condensate via the discharge lines 6, 7, 8 to a respective separator S1, S2, S3 for the removal of vapor and condensate. The condensate of the heating group 2 is fed via the condensate line 10 to a condensate collector. The condensate of the heating group 1 is supplied from the separator 1 via the condensate line 9 of the discharge line 7. Accordingly, condensate of the heating group 3 is also supplied from the separator 3 via the condensate line 11 to the discharge line 7 of the heating group 2. The Brüdendampf the heating group HG3 is supplied from the separator 3 via the vapor line 14 of the steam supply line 4 of the second heating group HG2 and used again for the paper drying directly. Accordingly, the Brüdendampf the heating group HG1 is supplied from the separator 1 via the vapor line 12 of the steam supply line 4 of the second heating group HG2 and used again for the paper drying directly. By contrast, the broth steam of the heating group HG2 is returned through the vapor line 13 via a thermocompressor from the separator 2 into the steam feed line 4 of the second heating group HG2, and thus also used directly again for the paper drying. The thermocompressor 15 acts as a jet pump, steam being used from the steam supply line 2 as the driving jet. The vapor pressure of the Brüdendampfes from the separator 2 of the heating group HG2 is characterized at least to the pressure level of Heating steam placed in the steam supply line 4. Like in the FIG. 2b by way of example, in contrast to the cascade system, the steam pressure PD of the heating steam in the heating groups HG1, HG2, HG3 is selected such that the first heating group HG1 has the highest vapor pressure PD, the second heating group HG2 the lowest vapor pressure PD and the third heating group HG3 a vapor pressure PD which is between the vapor pressure of the first heating group HG1 and the second heating group HG2.

The FIG. 3 shows a practical, more detail comprehensive embodiment of a heating subset according to the invention after Figure 2a and 2b for a dryer section of a paper machine with drying cylinders 1.1, 1.2, 1.3, 1.4, 2.1, 2.2, 3.1, 3.2 comprising 3 heating groups HG1, HG2, HG3. The heating groups are heated with heating steam. The steam supply pipes 3, 4, 5 are connected to a steam supply pipe 2. The steam supply lines 2 are supplied by a steam supply system DV with heating steam. The first heating group HG1 comprises the drying cylinders 1.1, 1.2, 1.3.1.4, the second heating group HG2 comprises the drying cylinders 2.1, 2.2 and the third heating group HG3 comprises the drying cylinders 3.1, 3.2. The heating groups HG1, HG2, HG3 are arranged successively with respect to the running direction of the paper machine. The heating group HG1 thus forms the first heating group and supplies several first drying cylinders 1.1, 1.2, 1.3, 1.4 with heating steam. The steam supply line 2 also supplies a night dryer section NTP or another steam consumer with steam. The vapor pressure of the respective heating steam can be set independently for each heating group HG1, HG2, HG3 by means of valves. After the heating steam of a heating group HG1, HG2, HG3 has passed through the drying cylinder, the mixture of vapor and condensate is fed via the discharge lines 6, 7, 8 to a respective separator S1, S2, S3 for the separation of the steam and condensate. The condensate of the heating group 2 is supplied via the condensate line 10 to a condensate collection container, wherein previously heat for the Haubenzuluft HZL was removed for the hood of the dryer section. The condensate of the heating group 1 is supplied from the separator 1 via the condensate line 9 of the discharge line 7. Accordingly, condensate of the heating group 3 is also supplied from the separator 3 via the condensate line 11 to the discharge line 7 of the heating group 2. The Brüdendampf the heating group HG3 is supplied from the separator 3 via the vapor line 14 of the steam supply line 4 of the second heating group HG2 and used again for the paper drying directly. Accordingly, the Brüdendampf the heating group HG1 from the separator 1 via the vapor line 12 of the steam supply line 4 of the second Heating group HG2 fed and used again for the paper drying directly. The Brüddenampf the heating group HG2, however, is returned by the vapor line 13 via a thermocompressor 15 from the separator 2 in the steam supply line 4 of the second heating group HG2 again and thus also used again for the paper drying directly. The thermocompressor 15 acts as a jet pump, steam being used from the steam supply line 2 as the driving jet. However, it is also conceivable to supply the thermocompressor 15 with steam from another steam supply network, for example a steam supply network with a higher vapor pressure. The vapor pressure of the Brüdendampfes from the separator 2 of the heating group HG2 is thereby brought at least to the pressure level of the heating steam in the steam supply line 4. Like in the FIG. 2b by way of example, in contrast to the cascade system, the steam pressure PD of the heating steam in the heating groups HG1, HG2, HG3 is selected such that the first heating group HG1 has the highest vapor pressure PD, the second heating group HG2 the lowest vapor pressure PD and the third heating group HG3 a vapor pressure PD which is between the vapor pressure of the first heating group HG1 and the second heating group HG2.

It is also possible to provide further heating groups between the first heating group HG1 and the last heating group HG3, these further heating groups also having a vapor pressure which is less than the vapor pressure of the first heating group HG1 and which is less than the vapor pressure of the last, ie in this Example of the third heating group is HG3. The condensate lines 9, 10, 11 and vapor lines 12, 13, 14 can then analogous to the heating subset shown FIG. 3 be connected to the steam supply lines or the discharge lines of one of the at least one further heating group or the heating group HG2.

In the event of a paper web break in the paper machine, ie outside the normal production operation of the machine, valves and vapor lines 12, 13, 14 are provided, shown here with arrows to direct the vapors directly to a capacitor KS. In addition, with this condenser, vapor lines 17 from other heating groups, not shown here, may be connected. The condenser KS is connected to lines CW for the supply and discharge of cooling water.

The heating group subsystem 1 also includes a vacuum separator V in the condensate lines from a post-dryer section NTP open. The vacuum separator V generates from it vapor vapor, which will be passed directly into the condenser KS.

In the FIG. 3 an optional thermocompressor 16 is provided with which it is possible to operate the heating group subsystem 1 as a classic cascade heating system, for example in the production of certain types of paper. The thermocompressor 16 acts as a jet pump, with steam from the steam supply line 2 being used as the driving jet. However, it is also conceivable to supply the thermocompressor 16 with steam from another steam supply network, for example a steam supply network with a higher vapor pressure. In this case, as seen in the running direction of the machine, the first heating group HG1 of the heating group subsystem 1 has the lowest vapor pressure of the heating steam of all the heating groups HG2, HG3 of the heating group subsystem 1 and the second heating group HG2 of the heating group subsystem 1 the second lowest vapor pressure and the third heating group HG3 the highest Vapor pressure of the heating steam. This thermocompressor 16 is connected to the vapor line 18 and to the steam supply line 2. This makes it possible in the case of cascade operation of the heating subset 1 of the resulting in the separator S1 and V in the vacuum separator vapor back into the steam supply line 3 of the heating group HG1 and directly to use for paper web drying. In this case, the vapor line 12 of the first heating group HG1 has a non-return valve 19 in order to prevent a backflow of heating steam from the steam supply line 4 via the vapor line 12 into the separator S1 of the first heating group HG1 or into the vacuum separator V.

If the heating group subsystem 1 according to the invention and not operated in cascade operation, the thermocompressor 16 may be out of service. The thermocompressor 16 can also be operated with steam from another steam supply network, for example a steam supply network with a higher vapor pressure. The vapor pressure of the Brüdendampfes from the vacuum separator V can thereby be brought at least to the pressure level of the heating steam in the Dampfzuführleitung 3 and used directly for the drying of the paper web.

The valves in the steam supply lines 3, 4, 5 are connected to pressure control systems PIC for controlling the vapor pressure of the respective heating steam and the valves the discharge lines 6, 7, 8 are coupled to pressure difference control systems PDIC. The valves in the condensate lines 9, 10, 11 are equipped with leveling LIC.

LIST OF REFERENCE NUMBERS

1

Heizgruppenteilsystem

2

Steam supply line

3

steam supply

4

steam supply

5

steam supply

6

discharge

7

discharge

8th

discharge

9

condensate line

10

condensate line

11

condensate line

12

vapor line

13

vapor line

14

vapor line

15

thermal compressor

16

thermal compressor

17

vapor line

18

vapor line

19

check valve

DV

Steam supply system

NTP

Afterdryers

HG1

Heating group 1

1.1

drying cylinders

1.2

drying cylinders

1.3

drying cylinders

1.4

drying cylinders

HG2

Heating group 2

2.1

drying cylinders

2.2

drying cylinders

HG3

Heating group 3

3.1

drying cylinders

3.2

drying cylinders

S1

Separator 1

S2

Separator 2

S3

Separator 3

KS

capacitor

KSB

condensate tank

HZL

hood supply

V

vacuum separator

CW

cooling water

Claims (14)

Method for operating a heating group subsystem (1) of a machine for producing or treating a fibrous web, in particular a paper or board web, wherein the heating group subsystem (1) has a first heating group (HG1) and a last heating group (HG3) and at least one further heating group (HG3) HG2), each comprising at least one device (1.1, 1.2, 1.3, 1.4, 2.1, 2.2, 3.1.3.2) heated with a steam pressure, in particular a drying cylinder, for heating the fibrous web, the fibrous web being viewed in the machine direction first through the first heating group (HG1), then through the at least one further heating group (HG2) and then through the last heating group (HG3),
characterized in that.
the vapor pressure of the heating steam of the at least one further heating group (HG2) is set lower than the respective vapor pressure of the heating steam of the first heating group (HG1) and the last heating group (HG3). Method according to claim 1,
characterized in that
the steam pressure of the heating steam of the first heating group (HG1) is set equal to or higher than the steam pressure of the heating steam of the last heating group (HG3). Method according to claim 2,
characterized in that
the vapor pressure of the heating steam of the at least one further heating group (HG2) is set in the range between 100 kPa and 700 kPa. Method according to one of the preceding claims,
characterized in that
the heating steam after flowing through the respective steam-heated device (1.1, 1.2, 1.3, 1.4, 2.1, 2.2, 3.1.3.2) is fed to a separator (S1, S2, S3) for the separation of condensate and Brüdendampf and the Brüdendampf the first heating group (HG1) and the at least one further heating group (HG2) and the last heating group (HG3) the heating steam of the steam-heated device (1.1, 1.2, 1.3, 1.4, 2.1, 2.2, 3.1.3.2) at least one of the at least one further heating group (HG2) is supplied. Method claim 4,
characterized in that
the vapor of the at least one further heating group (HG2) via a thermocompressor (15) to the heating steam of the steam-heated device (1.1, 1.2, 1.3, 1.4, 2.1, 2.2, 3.1.3.2) of at least one of the at least one further heating group (HG2) is supplied. Method according to one of the preceding claims,
characterized in that
the heating group subsystem (1), seen in the direction of the machine comprising a dryer section or a pre-dryer section and an after-dryer section, is provided at the beginning of the dryer section or at the beginning of the pre-dryer section or at the beginning of the after-dryer section of the machine. Heizgruppenteilsystem (1) a machine for producing or treating a fibrous web, in particular a paper or board web, said Heizgruppenteilsystem (1) a first heating group (HG1) and a last heating group (HG3) and at least one further heating group (HG2), each with at least a device (1.1, 1.2, 1.3, 1.4, 2.1, 2.2, 3.1.3.2) heated with a steam pressure, in particular a drying cylinder, for heating the fibrous web, wherein the Fibrous web seen in the machine direction first through the first heating group (HG1), then through the at least one further heating group (HG2) and then through the last heating group (HG3),
characterized in that
the vapor pressure of the heating steam of the at least one further heating group (HG2) is lower than the respective vapor pressure of the heating steam of the first heating group (HG1) and the last heating group (HG3). Heating subsystem according to claim 7,
characterized in that
the vapor pressure of the heating steam of the first heating group (HG1) is selected to be equal to or higher than the vapor pressure of the heating steam of the last heating group (HG3). Heating subsystem according to one of claims 7 or 8,
characterized in that
the respective heating group (HG1, HG2, HG3) and thus the respective at least one device heated with heating steam (1.1, 1.2, 1.3, 1.4, 2.1, 2.2, 3.1.3.2) via a steam supply line (3, 4, 5) with a steam supply line (2) is connected and each heating group is a separator (S1, S2, S3) associated with the separation of condensate and Brüdendampf, each via a discharge line (6, 7, 8) with the respective heating group (HG1, HG2, HG3) and the respective steam-heated device (1.1, 1.2, 1.3, 1.4, 2.1, 2.2, 3.1.3.2) is connected and that the separator (S1) of the first heating group (HG1) and the separator (S2) of the at least one further heating group ( HG2) and the separator (S3) of the last heating group (HG3) via a vapor line (12, 13, 14) to the steam supply line (4) of the at least one further heating group (HG2) is connected. Heating subsystem according to one of claims 7 to 9,
characterized in that
the vapor line (13) of the vapor from the separator (S2) of the at least one another heating group for compression via a thermocompressor (15) with the steam supply line (4) is connected, wherein the thermocompressor (15) is preferably connected to the steam supply line (2). Heating subsystem according to one of claims 7 to 10,
characterized in that
the respective condensate line (9, 11) of the separator (S1) of the first heating group (HG1) and the separator (S3) of the last heating group (HG3) is connected to the discharge line (7) of the at least one further heating group (HG2). Heating subsystem according to one of claims 9 to 11,
characterized in that
the vapor line 12 of the first heating group (HG1) has a backflow prevention device, for example a non-return valve (19). Heating subsystem according to one of claims 7 to 12,
characterized in that
a vacuum separator (V) is provided which is connected via a vapor line (18) to a thermocompressor (16), and that the vapor of the vacuum separator (V) is compressed by the thermocompressor (16) and the steam supply line (3) of the first heating group (16) HG1) is supplied. Heating subsystem according to one of claims 7 to 13,
characterized in that
the heating group subsystem (1), viewed in the direction of the machine comprising a drying section or a pre-drying section and a after-drying section, is provided at the beginning of the drying section or at the beginning of the pre-drying section or at the beginning of the after-drying section of the machine.

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