EP0969259A2 - Dryer with air circulation - Google Patents

Abstract

The dryer for textile piecegoods, using recirculating air, has a shaft (31) for the bypass flap (30) in the lower half of the bypass opening (29). The bypass flap (30) has a longer (32) and a shorter (33) leg. The length of the longer leg (32) is at least equal to the gap between the shaft (31) and the upper edge (34) of the deflection plate (24). To set the flap (30) into the bypass setting, the bypass opening (29) is divided into two sections. One part is a flow section (37) linked to the pressure chamber (25) and a suction section (38) is connected to the distribution chamber (26). The dimensions of the opening of the flow section (37) to the opening of the suction section (38) are in a ratio of 2.5 to 5.0. The bypass flap (30) is at an acute angle to the vertical, with its upper end offset towards the distribution chamber (25). The shaft (31) for the bypass flap (30) is higher than the upper edge (34) of the deflection plate (24). Limit stops (40,41) with spring plates (42,43) are at the upper and lower ends of the bypass opening (29).

Description

The invention relates to a circulating air dryer according to the preamble of claim 1.

This application is an additional application to the main application DE 198 29 134, in which the subject matter of the invention is described.

In such continuously operated circulating air dryers there is the at standstill Web or in the case of similar faults the problem of over-drying the Goods web. To avoid overdrying, it is known that Treatment agent instead of through the nozzle boxes onto the web via one Lead bypass directly into the return flow rooms of the circulating air dryer.

DE-A 40 33 637 describes a bypass valve as prior art, through which a circulating air flow with closed regulating flaps in the nozzle bodies, also called nozzle boxes, can be directed past the nozzle bodies.

In addition, from DE-A 40 33 637 distribution elements for an adjustable Treatment agent flow known in the nozzle body or in the bypass openings. The distribution elements are at the inlet for the circulating air on the upper nozzle body or on lower nozzle body arranged. The distribution organs can, depending on the position Close the bypass openings or the inflow openings.

Similar elements arranged on the nozzle boxes, through which optional Bypass openings or inflow openings to the nozzle boxes are closed can be known from DE-C 33 36 331 and from DD 208 210.

In the main application DE 198 29 134 there is a central, rotatably mounted one Bypass valve shown. The bypass flap closes in the normal position, i. H. in vertical position, a bypass opening. In the case of DE 198 29 134 vertically arranged sheet, in the following called baffle, in one Pressure chamber and a distribution chamber divided, the pressure side of the Recirculation fan is connected to the pressure chamber, the baffle on the the recirculation fan opposite the end of the pressure chamber an opening leaves through which the distribution chamber is connected to the pressure chamber, and Supply air openings of the nozzle boxes open into the distribution chamber.

The bypass opening is at the level of the distribution chamber with the Pressure chamber connecting opening and connects the distribution chamber with a backflow space above the upper nozzle boxes.

In bypass position, i.e. in a horizontal position, it protrudes into the area of a Top edge of the baffle. In this area there is turbulence an uneven flow to the bypass opening and the risk of Adjust the bypass flap. Part of the treatment agent flow will between the baffle plate and the bypass flap to the nozzle boxes. For Prevention of contact of hot treatment agent with the web this places high demands on the tightness of the closed Distribution flaps of the nozzle boxes provided.

The object of the invention is a circulating air dryer according to the preamble of Claim 1 to develop so that the turbulence on the bypass valve can be reduced or avoided and thus safe bypass operation is guaranteed.

The object is achieved by the characterizing features of claim 1.

Instead of a bypass flap rotatably mounted in the center, one can be rotated off-center stored bypass valve provided. For this purpose, the bypass valve has an off-center arranged shaft on that the bypass valve in a longer and in one shorter leg divides. The shaft of the bypass valve is in the lower half of the Bypass opening arranged. The length of the longer leg corresponds at least the distance between the shaft and the top edge of the Baffle plates.

The shaft of the bypass valve is rotatably supported at its ends and with means for Turn the shaft and thus to rotate the bypass flap about an axis of rotation of the Shaft.

Instead of with a while, the bypass valve can be provided with means by which the Bypass valve is rotatable about an eccentrically arranged axis of rotation. Essential is the off-center position of the axis of rotation.

In bypass operation, the bypass flap is turned so far that the end of the longer leg ends with the upper edge of the baffle (Bypass position). The treatment agent flows out of the pressure chamber along the Bypass valve in the backflow chamber. The bypass flap closes the area the distribution chamber into which the supply air openings of the nozzle boxes open the treatment agent flow. The hot treatment agent is from the Material web kept away, i.e. safe bypass operation is guaranteed.

Because of the eccentric shaft and the smaller lower leg the bypass flap remains next to an upper flow section of the Bypass opening through which the treatment agent flows, a lower one Suction section of the bypass opening is free. This lower suction section connects the distribution chamber with the backflow space. By the flow pressure of the flowing through the upper flow section of the bypass opening Treatment agent arises below the lower suction section of the Bypass opening, and thus in the distribution area in front of the nozzle boxes Vacuum. This negative pressure causes treatment agents from the Distribution room and, if necessary, is sucked out of the nozzle boxes. This arrangement increases the safety with which an overheating of the material web at standstill is avoided.

Another advantage of the negative pressure generated in the distribution space is that Bypass valve does not have to be sealed on its contact edge on the sheet.

If the bypass flap, e.g. when the web is at a standstill, in the bypass position rotated, the pressure of the treatment agent in the Nozzle boxes and thus dismantled on the web. Bypass operation continues faster. The bypass valve is highly effective.

A ratio of the openings of the flow section to the suction section of the Bypass opening from 2.5 to 5 to 1 according to claim 2 represents the generation of a Vacuum in the distribution chamber in front of the nozzle boxes.

An arrangement of the bypass valve in normal operation at an acute angle to Vertical, with its upper end offset from the distribution chamber is equalizes the flow cross-section in the area of the deflection from the Pressure chamber through the opening in the distribution chamber and thus improves the Flow of treatment agent. The bypass flap also acts higher flow pressure, which simplifies safe closing in normal operation. The acute angle to the vertical can be 10 to 40 °.

According to claim 4, the shaft and thus the axis of rotation of the bypass valve is higher arranged as the upper edge of the baffle. In bypass position Bypass valve arranged at an acute angle to the horizontal, being her front end facing down This has the advantage that when closing the Bypass valve closing by the flow pressure of the treatment agent is supported as soon as the bypass flap has exceeded the horizontal position. The acute angle to the horizontal can be 10 to 40 °.

Stops with spring plates at the top and bottom of the bypass opening according to claim 5 ensures safe closing in normal operation. The The bypass valve is pressed against the spring plates by the flow pressure.

The invention is illustrated schematically in the drawing Example further explained.

Figure 1 shows the cross section through a field of a circulating air dryer with a Bypass valve in normal position. Figure 2 corresponds to Figure 1, with the bypass valve is shown in the bypass position. The flow directions of the treatment agent are represented by arrows.

Figure 3 shows an enlarged view of the bypass valve in the bypass position.

Reference numerals 1 to 28 except 23 denote the same Items as in the main application, to which express reference is made here is taken.

A circulating air dryer according to the invention has several in the transport direction consecutive fields, for example six fields and one Transport device for a web 1, namely with a plane tenter frame a tension chain 2 leading horizontally through the fields of the circulating air dryer.

The circulating air dryer has a cuboid, insulated housing with side Housing walls 3, 4, a housing base 5 and a housing cover 6 Mistake. The fields are separated by partitions, not shown in the drawing Openings for the web 1 and the tension chain 2 and possibly with flaps, separated from each other.

In each field there is a recirculation device with at least one above and at least one nozzle box 7 arranged below the web 1 a circulating air fan 8, a suction chamber 9 on the suction side of the Air circulation fan 8 and a supply air chamber 10 on the pressure side of the Air circulation fan 8 arranged. In this example there are two top fields in each field and two lower nozzle boxes 7 arranged one behind the other in the transport direction. The Nozzle boxes 7 extend at least over the maximum in their length Web width and about 70% of the width of the circulating air dryer.

The nozzle boxes 7 are designed as cuboid sheet metal boxes. You point evenly distributed pipe sections 11 for backflow of the exhaust air, which the Material web 1 facing walls 12 with the opposite walls 13 of the Nozzle boxes 7 connects. The walls 12 facing the web 1 Nozzle boxes 7 are circular, not shown in detail with the Pipe sections 11 provided discharge openings. Feed openings 14 the nozzle boxes 7 of a field are all on one side, namely in this example on the side facing the housing wall 3, and extend almost over the entire height and width of the nozzle boxes 7. On this page the nozzle boxes 7 protrude somewhat beyond the tension chain 2.

Starting from the housing cover 6, one extends to the housing wall 3 facing ends of the nozzle boxes 7 which have the feed openings 14 arranged, parallel to the housing wall 3 intermediate wall 15 to Housing base 5. It separates the supply air chamber 10 from the interior of the field from. On this intermediate wall 15 one of the opposite Housing wall 4 outgoing intermediate floor 16, which the suction chamber 9 from Separates interior. The height of the suction chamber 9 is about a quarter of the Overall height.

Above, below and on the side of the housing wall 4 facing the nozzle boxes 7 arranged centrally along the dryer width remain from the Partition wall 15, the housing cover 6, the housing wall 4 and the Intermediate floor 16 limited backflow spaces 17, 18, 19 free. Below the lateral backflow space 19 is at least one filter 20 in the intermediate floor 16 admitted. Through the filter 20 are the backflow spaces open to each other 17, 18, 19 with the through the intermediate floor 16 and the housing base 5th limited suction chambers 9 connected. Below the filter 20, for example in the middle of the field length is a heater on the housing wall 4, here a Burner 21, for example a gas burner, is arranged. The one as a radial fan trained recirculation fan 8 is on the opposite burner 21 Side, also in the mine of field length at the end of the suction chamber 9 in the Supply air chamber 10 is arranged so that its pressure side is in the supply air chamber 10 located. Its suction side is through an opening 22 in the intermediate wall 15 with the Suction chamber 9 connected. The intermediate floor 16 is to improve the Inflow of the air circulation fan 8 angled upwards before it is directly above the opening 22 abuts the intermediate wall 15.

In the supply air chamber 10 there is a baffle plate 24 forming an intermediate wall arranged. At least in the upper area parallel to the housing wall 3 Running baffle 24 divides the supply air chamber 10 into two large ones Areas of the dryer height extending chambers in a Pressure chamber 25 and a distribution chamber 26. This is the Pressure side of the air circulation fan 8 in the pressure chamber 25. The deflection plate 24 ends at a distance from the housing cover 6, as a result of which the deflection plate 24 formed partition at the end opposite the air circulation fan 8 the pressure chamber 25, an opening 27 remains free through which the distribution chamber 26 is connected to the pressure chamber 25. Open into the distribution chamber 26 successively from top to bottom, the feed openings 14 of the top Nozzle boxes 7 and those of the lower nozzle boxes 7. The horizontal width of the Pressure chamber 25 in the upper area, the vertical height of the opening 27 and the horizontal width of the distribution chamber 26 in the upper region are the same size. The baffle plate forming the intermediate wall has, beginning at the height of the Material web 1 has a tapering the distribution chamber 26, which the Width of the distribution chamber 26 approximately at the center of the feed openings 14 on the Half reduced so that it corresponds to the height of the feed opening 14. By a 90 ° bend of the sheet 24 at the level facing away from the web 1 Walls 13 of the lower nozzle boxes 7, the distribution chamber 26 is down limited. The end of the baffle 24 is on the intermediate wall 15 on this Fixed height. Behind the feed openings 14 of the nozzle boxes 7 are in the Nozzle boxes 7 distribution flaps 28 are provided.

The intermediate wall 15 has at least one above the upper nozzle boxes 7 Bypass opening 29. The bypass opening 29 connects the distribution chamber 26 with the return flow chamber 17 located above the upper nozzle boxes 7 extends from the upper nozzle boxes 7 to the housing cover 6.

A bypass flap 30 is arranged in the bypass opening 29. The bypass valve 30 has an eccentrically arranged shaft 31 and therefore a longer one Leg 32 and a shorter leg 33. The shaft 31 is in the lower Half of the bypass opening 29 arranged so that the longer in the normal position Leg 32 upwards and the shorter leg 33 downwards and the Bypass flap 30 closes the bypass opening 29.

The length of the longer leg 32 corresponds at least to the distance between the shaft 31 and an upper edge 34 of the deflection plate 24.

The shaft 31 extends across the entire width of the field and is on both Sides rotatably supported The two legs 32 and 33 are on the shaft 31 attached. You can, as shown in Figure 3, from a common, rectangular sheet 35 exist that 31 bends for receiving the shaft having. One can also on the opposite side of the folds folded mounting plate 36 may be arranged.

The legs 32 and 33 of the bypass valve 30 can also each have one the shaft 31 attached rectangular sheet.

In the bypass position, the bypass opening 29 is in one through the bypass flap 30 divided upper flow section 37 and a lower suction section 38. The ratio of the openings of the flow section 27 and the Suction section 38 is 2.5 to 5 to 1. It is determined by the ratio of Lengths of the legs 32 and 33 and any additional sheet metal determined. In this For example, the ratio of the leg lengths is approximately 3.2 to 1.

In the normal position, the bypass opening 29 and the bypass flap 30 run in one acute angle to the vertical from 10 to 40 °, for example from 26 °, the upper End of the bypass valve 30, i.e. of her longer leg 31, for Distribution chamber 26 is arranged offset.

The shaft 31 of the bypass valve 30 is located above the upper edge 34 of the Deflection plate 24, whereby the bypass valve 30 in bypass operation in one acute angle is arranged down to the horizontal from 10 to 40 °. The Angle can also be 26 °, so that normal position and bypass position form a right angle to each other.

The upper edge of the deflection plate 24 projects beyond the upper nozzle boxes 7. At the front, upper edge of the upper nozzle boxes 7 there is an additional one Sheet metal, namely a spacer sheet 39 ending approximately with the upper edge 34, attached.

On the housing cover 6 and on the spacer plate 39 of the upper nozzle boxes 7 stops 40, 41 with spring plates 42, 43 are arranged. The profile of the Spring plates 42, 43 can have the shape of a triangle, one side only a small part is made of sheet metal and the rest of the page is Travel forms.

The arrangement of the air circulation fan over the field length is variable; he can in the middle, be arranged at the beginning or end of the field.

In normal operation, the treatment agent, i.e. H. the drying air through which Nozzle boxes 7 fed via the outflow openings of the web 1. The Drying air takes the moisture of the web 1 while releasing its heat and flows as exhaust air through the pipe sections 11 through the nozzle boxes 7 and to the side of the nozzle boxes 7 into the return flow spaces 17, 18, 19. Part of the exhaust air of a field, for example with countercurrent flow in the circulating air dryer, into the previous field and a corresponding part of the exhaust air from the one behind Field directed into the backflow spaces 17, 18 or 19 of this field. The from the Backflow spaces 17, 18, 19 coming exhaust air is cleaned in the filter 20, in the Intake chamber 9 heated to drying air by means of the burner 21, through the Recirculated air fan 8 sucked in via the pressure chamber 25, the opening 27 and the Distribution chamber 26 of the feed chamber 10 pressed into the nozzle boxes 7. On on its way through the divided feed chamber 10, the flow of the Drying air evened out. The flow path of the drying air, in particular to the lower nozzle boxes 7 is enlarged up to 5 times. It finds a conversion of dynamic pressure and static pressure in the Flow instead. Turbulence is prevented. Missing flow obstacles allow a uniform loading of the nozzle boxes 7 at one low energy consumption.

The oblique course of the bypass opening 29 and the bypass flap 30 equalizes the flow of the treatment path from the pressure chamber 25 through the opening 27 into the distribution chamber 26. The bypass valve 30 is thereby pressed against the spring plates 42 and 43 by the flow pressure.

For the bypass operation, the bypass flap 30 is rotated into the bypass position. The Treatment agent flows evenly out of the pressure chamber 25 through the opening 27 in the deflection plate 24, along the bypass flap 30, through the Flow section 37 of the bypass opening 29 into the return flow space 17 the flow pressure of the treatment agent is in the suction section 38 Bypass valve 30 and in the distribution chamber 26 below generated a negative pressure. Thereby treatment agent from the distribution space 26 and possibly from the Extracted nozzle boxes 7. The distribution flaps 28 are not closed necessary. The pressure is within a very short time, for example of 1 second of the treatment agent in the nozzle boxes and on the web.

Reference list

1.

Goods web

2nd

Tension chain

3rd

Housing wall

4th

Housing wall

5.

Case back

6.

Housing cover

7.

Nozzle box

8th.

Air circulation fan

9.

Suction chamber

10th

Supply air chamber

11.

Pipe section in the nozzle box

12th

Wall of the nozzle box

13.

Wall of the nozzle box

14.

Feed opening of the nozzle box

15.

Partition wall of the dryer field

16.

Intermediate floor of the dryer field

17th

Upper backflow space

18th

Lower backflow space

19th

Lateral return flow space

20th

filter

21.

burner

22.

Opening in the partition

23.

-

24th

sheet

25th

Pressure chamber

26.

Distribution chamber

27.

opening

28

Distribution flaps

29.

Bypass opening

30th

Bypass valve

31

wave

32.

Longer leg

33.

Shorter thigh

34.

Top edge

35.

sheet

36

. Mounting plate

37.

Flow section

38.

Suction section

39.

Spacer plate

40.

attack

41.

attack

42.

Spring plate

43.

Spring plate

Claims (5)

Circulating air dryer with one or more fields arranged one behind the other, with a horizontal transport device for one web, in each field with a recirculation device with at least one above and at least one below the web Nozzle box, with a fan, with an intake chamber, the Suction side of the fan is connected to the suction chamber, and with a supply air chamber, the supply air chamber being on one side of the web the recirculation fan is located at the lower end of the supply air chamber, the supply air chamber through a substantially vertically arranged baffle is divided into a pressure chamber and a distribution chamber, the pressure side of the air circulation fan is connected to the pressure chamber, the baffle at the end of the pressure chamber opposite the recirculation fan Leaves opening through which the distribution chamber with the pressure chamber is connected, supply air openings of the nozzle boxes into the distribution chamber open out at the level of the distribution chamber and the pressure chamber connecting opening is a bypass opening that the distribution chamber connects with a backflow space above the nozzle box and through a bypass flap can be closed with a shaft, characterized in that that the shaft (31) of the bypass valve (30) in the lower half of the Bypass opening (29) is arranged and the bypass flap (30) a longer one Has leg (32) and a shorter leg (33), the length of the longer leg (32) at least the distance between the shaft (31) and corresponds to an upper edge (34) of the deflection plate (24). Circulating air dryer according to claim 1, characterized in that at Bypass position of the bypass flap (30), the bypass opening (29) in one with the Pressure chamber (25) connected flow section (37) and one with the Distribution chamber (26) connected suction section (38) is divided and that Ratio of the openings of the flow section (37) to the suction section (38) 2.5 to 5 to 1. Circulating air dryer according to claim 1 or 2, characterized in that the Bypass valve (30) at an acute angle to the vertical and with its upper End is arranged offset to the distribution chamber (25). Circulating air dryer according to one of claims 1 to 3, characterized in that the shaft (31) of the bypass flap (30) higher than the upper edge (34) of the Deflection plate (24) is arranged. Circulating air dryer according to one of claims 1 to 4, characterized in that stops (40, 41) at the upper and lower ends of the bypass opening (29) with spring plates (42, 43) are arranged.

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