TWI866396B - Fabric drying device - Google Patents

Abstract

A textile web drying device (1) having a plurality of drying cylinders (3-12), the surfaces (17) of which form part of a textile web path, wherein a first drying cylinder (3-10) is arranged in a first section of the textile web path, a second drying cylinder (11, 12) is arranged in a second section of the textile web path following the first section, and each drying cylinder has a steam inlet (13) and a condensate outlet (14) connected to a steam supply device (20) and an inner space (15) of the drying cylinder, in order to make the best possible use of the available energy. To this end, the condensate outlet of the first drying cylinder is arranged to be connected via a condensate separator (23) to a discharge container (22), which has a steam outlet (33) and a liquid outlet (38), wherein the steam outlet is connected to a pressure increasing device, the outlet of which is connected to the steam inlet of at least one second drying cylinder.

Description

Fabric width drying device

The invention relates to a textile web drying device having a plurality of drying cylinders, the surfaces of which form part of a textile web path, wherein a first drying cylinder is arranged in a first section of the textile web path and a second drying cylinder is arranged in a second section of the textile web path following the first section, and each drying cylinder has a steam inlet connected to a steam supply device and the interior space of the drying cylinder and a condensate outlet.

EP 3 339 507 A1 describes a method for operating a heating group subsystem and a heating group subsystem, wherein the heating group can have a drying cylinder. The drying cylinder is heated with different steam pressures. When waste steam (Abdampf) escapes from the working group, the pressure can be increased in order to supply this steam with increased pressure to the following working group. The device is used for heating fiber webs, in particular paper webs or cardboard webs. In paper machines, processing speeds of more than 2000 m/min are achieved with a drying cylinder diameter of more than 1500 mm.

The textile web can be in the form of a continuous textile, such as a woven or knitted fabric, or in the form of a yarn. Regardless of the form of the textile web, it is often necessary to load the textile web with a dye liquor during the production process, whereupon the textile web must be dried again. However, textile webs generally have a much lower speed than fiber webs, i.e. in most cases up to 200 m/min, which is generally a factor of ten lower than the speed for paper or cardboard webs. As a result, the drying cylinder can be operated at a relatively low rotational speed, so that the steam condensing in the interior of the drying cylinder is subjected to relatively low centrifugal forces and no liquid film can be formed on the inside of the drying cylinder or only a liquid film with a relatively small thickness can be formed. On the contrary, at such low rotational speeds, condensate accumulates in the lower area of the drying cylinder and forms a condensate pocket there. This results in good heat transfer from the steam fed into the drying cylinder to the circumferential wall of the drying cylinder. The textile web to be dried rests against the outer side of the circumferential wall.

The present invention is based on the following task, which is able to promote the drying process with as little energy as possible.

This object is achieved in a textile web drying device of the type mentioned at the outset in that the condensate outlet of the first drying cylinder is connected via a condensate separator to a discharge container having a steam outlet and a liquid outlet, wherein the steam outlet is connected to a pressure increasing device, the outlet of which is connected to the steam inlet of at least one second drying cylinder.

The condensate separator ensures that the condensate reaches the discharge container and practically prevents the transfer of steam into the discharge container. Small leaks may occur but are not critical. The condensate separator thus also ensures a pressure decoupling between the drying cylinder and the discharge container, so that the pressure in the discharge container can be kept at a relatively low level. The energy content of the condensate, which is always still at a relatively high temperature level, can thus be better utilized. Due to the lower pressure in the discharge container, at least part of the condensate can evaporate again there. The steam formed in this way can then be supplied to the second drying cylinder via a pressure increase device, so that at least part of the energy content of the condensate can be used to heat the second drying cylinder.

In a preferred design, the pressure increasing device is configured as a steam jet pump, the suction side of which is connected to the unloading container. The steam jet pump uses steam as a propellant in order to bring the steam obtained from the condensate back to increase the pressure. Therefore, it is possible to use the same medium as the medium whose pressure is to be increased for increasing the pressure.

It is also preferred that the steam jet pump is connected to the same steam supply as the first drying cylinder. Thus, no additional steam source is required, but steam from the steam supply which also heats the first drying cylinder can be used. This keeps the total cost low overall.

Preferably, the condensate separator has a condensate collection space in which a float is arranged, which float cooperates with a valve at the condensate flow outlet. The float always floats on or at the surface of the condensate accumulated in the condensate collection space. The valve thus opens depending on whether condensate is present in the condensate collection space. The valve is only opened if condensate is present there. If the condensate level drops too far, the float-controlled valve is closed, so that practically no steam can escape through the condensate separator. The valve thus automatically causes a pressure separation between the drying cylinder and the unloading container.

It is also advantageous if the float opens the valve in the case of a first fill level of condensate in the condensate collection space and closes the valve in the case of a second fill level of condensate which is different from the first fill level. Thus, a certain hysteresis is produced. For example, the valve opens only when the condensate in the condensate collection space reaches a first level and closes when the condensate reaches a second level which is lower than the first level.

It is also advantageous if the condensate flow outlet is arranged downward in the direction of gravity. This is an additional measure to increase safety against steam escaping from the condensate separator.

Preferably, the number of first drying cylinders is greater than the number of second drying cylinders. Thus, the number of drying cylinders operating at a higher temperature is greater than the number of drying cylinders operating at a lower temperature. The second drying cylinders can then be used for a kind of "follow-up drying (Nachtrocknung)".

Preferably, the condensate outlet of the drying cylinder is connected to a channel having an inlet which is arranged at a position in the interior space which is located downward in the direction of gravity. For example, the channel can be constructed in a siphon or in a hose line or a pipe line, the entry of which is immersed in a condensate well which is constructed in the interior of the drying cylinder in a region located downward in the direction of gravity. Due to the pressure existing in the drying cylinder caused by the steam supply device, the condensate is then transported through the channel to the condensate outlet and from there to the condensate separator.

In a preferred embodiment, it is provided that steam with a pressure in the range of 3.5 bar to 6.0 bar is present at the steam inlet of the first drying cylinder. Thus, a temperature of the drying cylinder in the range of 147° C. to 164° C. can be achieved, which is sufficient for drying the textile material web.

It is also advantageous if the difference between the pressure in the interior of the first drying cylinder and the pressure in the unloading container is at least 2.0 bar, for example to about 4.3 bar. When a pressure of 0.2 bar to 1.2 bar is present in the unloading container and the condensate in the drying cylinder has a temperature of about 147° C. to 164° C., part of the condensate in the unloading container evaporates. The low-pressure steam thus produced can be supplied to the second drying cylinder. Taking into account the energy required for the pressure-increasing device, a good utilization of the total energy can thus also be achieved.

Advantageously, the pressure increasing device causes a pressure increase in the range of more than 0.5 bar. Depending on the pressure increasing device, a pressure increase of 0.8 bar to 1.0 bar or even 0.5 bar to 1.8 bar can be achieved. This is sufficient to supply the second drying cylinder with the necessary temperature.

1: Fabric width drying device

2: Fabric width

3-12: Drying tank

13: Steam inlet

14: Condensate outlet

15: Internal space

16: Circumferential wall

17: Surface

18: Channel

19: Pipeline

20: Steam generator

21: Regulating valve

22: Unloading container

23: Condensate separator

24: Entrance

25: Condensate accumulation space

26: Condensate flow outlet

27: Valve

28: Float

29: Condensate

30: Operating equipment

31: The first manipulative geometry structure

32: The second manipulative geometry structure

33: Steam outlet

34: Steam jet pump

35,36: Sensor

37:Transport pump

38: Liquid outlet

The present invention is described below according to a preferred embodiment in conjunction with the accompanying drawings. Among them: Figure 1 shows a schematic diagram of a fabric web drying device, Figure 2 shows a schematic diagram of the guidance of steam and condensate in the fabric web drying device, Figure 3 shows a schematic diagram of a condensate separator, and Figure 4 shows a schematic diagram of a drying cylinder.

FIG. 1 shows very schematically a textile web drying device 1 through which a textile web 2 runs. The textile web 2 runs over a plurality of drying cylinders 3 to 12. The textile web 2 rests against the surface of the drying cylinders 3 to 12. The surface of the drying cylinders 3 to 12 forms part of the path of the textile web.

The drying cylinders 3 to 12 are divided into at least two groups, wherein the drying cylinders 3 to 10 form the first drying cylinder and the drying cylinders 11, 12 form the second drying cylinder. Accordingly, the textile web 2 first travels on the first drying cylinders 3 to 10 and then on the second drying cylinders 11, 12.

As shown in FIG. 4 with respect to the drying cylinder 3, each drying cylinder 3 to 12 has a steam inlet 13 and a condensate outlet 14. The other drying cylinders 4 to 12 are also constructed in principle in the same way. The steam inlet 13 is connected to the interior 15 of the drying cylinder 3. The interior 15 of the drying cylinder 3 is surrounded by a circumferential wall 16, the outer surface 17 of which forms a circumferential surface against which the textile web 2 rests during drying.

The condensate outlet 14 is connected to the channel 18. The channel 18 can be constructed in a line or pipe 19, the opening of which is arranged at a region of the inner space 15 that is above and below in the direction of gravity. The condensate accumulated in this region is then squeezed to the condensate outlet 14 by the steam pressure existing in the inner space 15 and can flow out from there.

FIG. 2 schematically shows the supply of drying cylinders 3 to 12 with steam for heating. The steam is provided by a steam generator 20 (e.g. a steam boiler). In this embodiment, the steam is provided here with a pressure of about 4 bar. The steam is supplied to the drying cylinders 3 to 10 via at least one regulating valve 21. The temperature of the drying cylinders 3 to 10 can be adjusted by means of at least one regulating valve 21. To this end, at least one regulating valve 21 can, for example, adjust the flow rate of steam to the drying cylinders 3 to 10. It is also possible to divide the drying cylinders 3 to 10 into a plurality of groups and to have each group or each drying cylinder 3 to 10 be equipped with its own regulating valve 21. Thus, different temperatures can be set in the drying cylinders of each group.

In the drying cylinders 3 to 10, the steam transfers at least part of its heat to the circumferential wall 16 and thus heats the surface 17 of the drying cylinders 3 to 10, so that the textile web 2 resting against the surface 17 of the drying cylinders 3 to 10 is heated and the liquid contained in the textile web 2 can evaporate. The steam introduced into the drying cylinders 3 to 10 then partially condenses. Due to the low rotation speed of the drying cylinders, this condensate accumulates essentially in the lower region of the interior 15, from where it can be discharged via the channel 18 and the condensate outlet 14.

The drying cylinders 3 to 10 are connected to the unloading container 22, wherein at least one condensate separator 23 is arranged between the drying cylinders 3 to 10 and the unloading container 22. The condensate separator 23 of the drying cylinder 10 is only provided with a reference numeral here. However, the corresponding condensate separator is arranged here at the condensate outlet 14 of each of the drying cylinders 3 to 10. The condensate separator 23 is connected to a common line, which in turn is connected to the inlet 24 of the unloading container 22.

FIG3 shows a schematic diagram of a condensate separator 23. The inlet 24 of the condensate separator is connected to the condensate outlet 14 and leads into the condensate accumulation space 25. The condensate accumulation space 25 has a condensate flow outlet 26 at its upper and lower ends in the gravity direction, which is controlled by a valve 27. The valve 27 can be constructed in a simple manner as an on/off valve, i.e. it opens and then allows the condensate 29 to flow out of the condensate accumulation space 25, or it closes and prevents the medium from flowing out of the condensate accumulation space 25.

A float 28 is arranged in the condensate accumulation space 25, which has a smaller specific weight than the schematically shown condensate 29. When the liquid level of the condensate 29 in the condensate accumulation space 25 rises, the float 28 moves upward in the direction of gravity. When the liquid level of the condensate 29 drops, the float 28 moves downward in the direction of gravity. The float 28 works together with the operating device 30 of the valve 27. The operating device 30 has a first operating geometry 31 and a second operating geometry 32. When the float 28 moves upward in the direction of gravity, the float acts on the first operating geometry 31 and thus opens the valve 27. When the level of the condensate 29 drops, then the float 28 acts on the second operating geometry 32 and closes the valve 27. Therefore, the valve 27 has a certain hysteresis, because it opens in the case of a first level of the condensate 29 in the condensate accumulation space 25 and closes in the case of a second level of the condensate 29 in the condensate accumulation space 25, wherein the first level is higher than the second level in the direction of gravity. The illustration in FIG. 3 is purely schematic.

The condensate separator 23 ensures that only condensate can reach the discharge container 22 from the drying cylinders 3 to 10 and that steam is virtually prevented from entering the discharge container 22. Small leaks, for example due to the valve 27 not being closed, are not critical here. The condensate separator 23 thus also causes the pressure in the interior 15 of the drying cylinders 3 to 10 to be decoupled from the pressure in the discharge container 22.

Since steam is supplied to the drying cylinders 3 to 10 via the steam inlet 13, the pressure in the drying cylinders does not drop significantly despite the condensation. However, a pressure loss occurs at the corresponding condensate separator 23, so that the condensate in the discharge vessel has a pressure of only about 0.3 bar to 0.9 bar, so that steam is generated due to the relatively high temperature of the inflowing condensate until the condensate is in thermal equilibrium again, i.e. no longer superheated. Depending on the actual pressure level in the discharge vessel, the condensate will then have a temperature of only about 107° C. to 115° C. The steam formed here is supplied from the steam outlet 33 of the discharge vessel 22 via a line to a pressure increasing device, which in this case is designed as a steam jet pump 34. The propellant inlet of the steam jet pump 34 is connected to the steam generator 20, so that the drying cylinders 3 to 10 and the steam jet pump 34 are supplied with steam from the same steam source, namely the steam generator 20.

The steam jet pump 34 increases the pressure of the steam from the unloading container by preferably more than 0.5 bar, for example 0.8 bar to 1.0 bar, so that the temperature of the steam input into the second drying cylinder 11, 12 is higher than the temperature of the condensate at the condensate flow outlet 26.

The condensate from the drying cylinders 11, 12 can be conveyed back into the discharge container 22, wherein here again the condensate separator 23 is arranged between the drying cylinders 11, 12 and the discharge container 22.

The unloading container 22 can have sensors 35, 36 which are connected to a delivery pump 37 which is connected to a liquid outlet 38 of the unloading container 22. The sensor 35 defines a maximum fill level for the condensate in the unloading container 22. When the condensate level reaches the sensor 35, the delivery pump 37 is put into operation and discharges the condensate, for example back to the steam generator 20. The sensor 36 defines a minimum fill level for the condensate in the unloading container 22. When the condensate level reaches the sensor 36, the delivery pump 37 is then switched off. The condensate outlets of the drying cylinders 11, 12 can also be connected directly to the liquid outlet 38 of the unloading container 22.

3-12: Drying tank

20: Steam generator

21: Regulating valve

22: Unloading container

23: Condensate separator

24: Entrance

33: Steam outlet

34: Steam jet pump

35,36: Sensor

37:Transport pump

38: Liquid outlet

Claims (11)

A textile web drying device (1) comprising a plurality of drying cylinders (3-12), the surfaces (17) of the drying cylinders forming part of a textile web path, wherein a first drying cylinder (3-10) is arranged in a first section of the textile web path, and the second drying cylinders (11, 12) are arranged in a second section of the textile web path following the first section, and each drying cylinder (3-12) has a steam supply device (20) and an internal air connection to the drying cylinder. The invention relates to a steam inlet (13) and a condensate outlet (14) connected to a first drying cylinder (3-10) via a condensate separator (23), wherein the condensate outlet (14) of the first drying cylinder (3-10) is connected to an unloading container (22), wherein the unloading container has a steam outlet (33) and a liquid outlet (38), wherein the steam outlet (33) is connected to a pressure increasing device, and the outlet of the pressure increasing device is connected to the steam inlet of at least one second drying cylinder (11, 12). The fabric web drying device as described in claim 1 is characterized in that the pressure increasing device is constructed as a steam jet pump (34), and the suction side of the steam jet pump is connected to the unloading container (22). The fabric web drying device as described in claim 2 is characterized in that the steam jet pump (34) is connected to the same steam supply device as the first drying cylinder (3-10). The fabric web drying device as described in any one of claims 1 to 3 is characterized in that the condensate separator (23) has a condensate accumulation space (25), a float (28) is arranged in the condensate accumulation space, and the float cooperates with a valve (27) at the condensate flow outlet (26). The textile web drying device as claimed in claim 4 is characterized in that the float (28) opens the valve (27) when the condensate (29) in the condensate accumulation space (25) reaches a first filling level, and closes the valve (27) when the condensate (29) reaches a second filling level different from the first filling level. The fabric web drying device as described in claim 4 is characterized in that the condensate flow outlet (26) is arranged downward in the direction of gravity. The fabric web drying device as described in claim 1 is characterized in that the number of the first drying cylinders (3-10) is greater than the number of the second drying cylinders (11, 12). The textile web drying device as claimed in claim 1 is characterized in that the condensate outlet (14) of the drying cylinder (3-12) is connected to a channel (18), the channel having an inlet, and the inlet is arranged at a position arranged downward in the direction of gravity in the internal space (15). The textile web drying device as claimed in claim 1 is characterized in that steam having a pressure in the range of 3.5 to 6.0 bar is present at the steam inlet (13) of the first drying cylinder (3-10). The textile web drying device as claimed in claim 1 is characterized in that the difference between the pressure in the inner space (15) of the first drying cylinder (3-10) and the pressure in the unloading container (22) is at least 2.0 bar. The textile web drying device as claimed in claim 1 is characterized in that the pressure increasing device causes a pressure increase in a range exceeding 0.5 bar.