DE102005007276A1 - Two-roll press system for dewatering paper, cardboard or tissue in a paper machine, comprises a flexible press roll, a larger mating roll and a conduit positioned so that expressed water runs over its wall and into the conduit - Google Patents

Abstract

A two-roll press system for dewatering paper etc. in a paper machine, in which the diameter of the flexible press roll is smaller than that of the mating roll and the water conduit is located with its boundary wall in such a position that the water thrown off at a tangent from between the rollers runs without hindrance over the wall and into the conduit. A press system for dewatering paper, cardboard or tissue etc. (1) in a paper production or finishing machine, comprises a press gap between two rollers (9, 13) with an angle of not more than 45[deg] between the press plane (17) and the horizontal, and with a continuous dewatering belt (2) passing through the gap along with the fibrous sheet (1); the roller (9) which is in contact with the belt (2) has a flexible sleeve (11) which is pressed against the mating roll (13) by a concave element (10), and there is a water drainage conduit (15) after the gap in the angle between the roll (9) and the belt (2), with a guide channel (16) formed by the roll (9) and the boundary wall (5) of the conduit (15). In this system, the diameter of the press roll (9) is smaller than that of the mating roll (13), while the boundary wall (5) is at such a distance from the roll (9) and extends only so far in the direction of rotation that the water thrown off at a tangent after the transition (14) from the concave to the convex shape of the roller sleeve (11) runs without hindrance over the wall (5) into the conduit (15).

Description

The The invention relates to a pressing arrangement for dewatering a paper, cardboard, Tissue or another fibrous web in a machine for Production and / or refinement thereof, consisting of one of two press rolls formed, extended press nip, whose Press plane with the horizontal forms an angle of maximum 45 ° and by the next to the fibrous web at least one endlessly circulating dewatering belt is guided, being with the drainage tape contacting press roll has a flexible roll shell, that of a pressing element with concave pressing surface to the cylindrical counter-pressure roller depressed is, after the press nip in the gusset between the press roll and the drainage tape one extending substantially along the pressure roller gutter to accommodate the thrown off water is present, the gape-side Boundary wall forms a guide channel with the press roller.

Press arrangements with a gully are for example from DE 102 22 432 A1 known. In this case, the efficiency of the drainage and thus the extent of rewetting of the dewatering belt is not satisfactory, especially in such an inclined or even horizontal press plane.

The The object of the invention is therefore to provide the removal of water to improve such pressing arrangements.

According to the invention was solved the task by that the diameter of the press roll is smaller than the diameter the counterpressure roller is and the gusset side boundary wall so far from the press roller and only so far in the direction of rotation that extends after the transition tangential from the convex to the concave shape of the roll mantle thrown off water largely unhindered over this Boundary wall enters the gutter.

To the press nip is the roll shell of the press roll of, from the concave pressing surface of the pressing element forced concave shape to one of the approximately cylindrical Form of the roll mantle embossed convex shape over.

Of the radius of curvature at this transition much smaller than the radius of the press roll, which is very high centrifugal entails.

By these high centrifugal forces will be a big one Part of the adhering to the roll shell water against the boundary wall or hurled a deflector. Due to the relatively high kinetic energy the thrown-off water easily passes through the guide channel in the gully.

This transition includes to the press nip and extends more than 20 °, preferably no more than 15 ° and in particular more than maximum 10 ° of the Roll circumference.

To the transition to the concave shape, the remaining water is substantially tangential from Thrown roll roll. The relatively large radius of the roll shell also results in lower centrifugal forces. As this thrown off Water but unhindered over the boundary wall can get into the gutter, affect the lower centrifugal forces not negative.

in the Result reaches a larger water content even without the use of, on the roll shell in the area of the gutter attached scrapers in the gully.

This reduces rewetting of the drainage tape considerably and protects the roll shell. The dewatering belt preferably runs over the Dewatering belt.

Of the smaller diameter of the roll shell of the press roll does not increase only the centrifugal forces acting on the adhering water or centrifugal forces, but also allows the closer approach of the Gully in the gusset. The gully can be so thrown off Catch water much more comprehensively.

Preferably Therefore, the diameter of the press roll should be at least 10%, preferably at least 25% and in particular at least 40 % smaller than the diameter of the counter-pressure roller.

Besides that is It is advantageous if at the gusset end of the gully a substantially along the pressure roller extending deflector located at the beginning of the guide channel forms with the upper press roll. This can be the beginning of the guide channel be placed relatively close to the Pressspaltende, so that possible much thrown off water can be led to the gully.

It is also advantageous if the deflector bar is in light contact with the drainage tape. The deflector bar can be so water strip from the dewatering belt and into the guide channel, from where it is dragged into the gutter.

It But it can also be advantageous if the deflector bar a small distance to the drainage belt having.

Around the effectiveness of the deflector as far as possible in the gusset should be able to shift into it they have an acute-angled end projecting into the gusset.

In the guide channel so gets the stripped from the deflector ledge from the drainage band as well that from the roll jacket to the deflector bar and to the boundary wall the gully flung water. This water should not to the drainage tape drip back and as possible comprehensive through the guide channel led into the gully become.

Reached This is especially due to the fact that between the deflector bar and the boundary wall of the gully compressed air into the guide channel is blown in the direction of rotation. This compressed air rips that in the guide channel came with water.

in the The area of the deflector bar produces this away from her Compressed air a negative pressure in the guide channel, the water from the area of the gusset towards the gully sucks.

The in the convex region of the roll shell after the transition tangentially thrown off water causes a deflection of the entrained by the compressed air water towards the catchment area of the gully.

Around Minimizing the formation of water mist is in the catchment area the gutter a Luftabsaugeinrichtung available.

Because of the usual problematic water drainage the use of the inventive solution is particularly suitable for a Press arrangement whose press rolls about a horizontal press plane form.

she is with advantages but also applicable to Pressanordnungen whose Press plane with the horizontal an angle of a maximum of 30 °, preferably maximum 15 ° forms.

there should inclinations of the press plane to the horizontal in both directions be detected, d. H. that the amounts of tilt angle are considered here.

following the invention is based on an embodiment be explained in more detail.

In the attached Drawing shows:

1 : A schematic cross section through a press arrangement and

2 : an enlarged section of it.

The press arrangement is of two juxtaposed press rolls 9 . 13 formed, wherein the press roll 9 a flexible roll shell 11 possesses, to the formation of an extended press nip with horizontal pressing plane 17 from a pressing element 10 with concave pressing surface to the cylindrical counter-pressure roller 13 is pressed.

Through this press nip is next to the fibrous web 1 one with the press roll 9 coming in contact, endless and water-absorbing drainage tape 2 guided. The drainage tape 2 serves to accommodate the in the press nip from the fibrous web 1 pressed water and runs over the fibrous web 1 ,

To increase the water absorbency, the roll shell has 11 the press roll 9 Grooving and blind holes on. The inside of the drainage tape 2 absorbed water must come back from the roll jacket after the press nip 11 be removed.

Essentially, this is done by the centrifuging of the roll shell 9 sticking water in a gusset between drainage tape 2 and press roll 9 existing gully 15 ,

This gully 15 has a boundary wall directed to the gusset 5 , which with the roll shell 11 the press roll 9 a guide channel 16 forms.

After, by the pressing element 10 forced in the press nip concave shape of the roll shell 11 closes a transition 14 at, which extends beyond the press nip over 15 ° of the roll circumference. In this transition 14 the roll shell approaches 11 more and more of the cylindrical roller shape.

In this transition 14 is the radius of curvature of the roll mantle 11 significantly, for example, 10 times smaller than the radius of curvature in the subsequent cylindrical, convex shape.

But the smaller radius of curvature has Also larger centrifugal or centrifugal forces result, during rotation on the roll shell 11 sticky water act. That's from this transition 14 Thrown off water therefore has sufficient kinetic energy to after impact on the opposite boundary wall 5 or a deflector bar 4 in the gully 15 to get.

After the transition 14 The remaining water is then tangential to the roll shell 11 over the boundary wall 5 out directly into the gully 15 spun. Since this is done directly, the reduced centrifugal or centrifugal forces of the water had an effect due to the larger radius of curvature after the transition 14 not negative.

In the gully 15 there is a water drain 8th for the collected water.

At the gusset end of the gully 15 is one, essentially along the press roll 9 extending deflector bar 4 that marks the beginning of the guide channel 16 with the press roll 9 forms.

This deflector bar 4 has one, in the gusset between press roll 9 and drainage tape 2 protruding, acute-angled end. This acute-angled end is connected to the drainage belt 2 in contact and so wipes water from the drainage tape 2 from.

To this stripped and that on the deflector bar 4 from the roll shell 11 Thrown off water as comprehensively as possible in the guide channel 16 to the gully 15 To be able to guide is between deflector bar 4 and boundary wall 5 via a blow-in channel 3 Compressed air in the guide channel 16 in the direction of rotation of the press roll 9 blown.

This compressed air travels in the guide channel 16 and at the boundary wall 5 water to the upper edge of the boundary wall 5 and beyond into the gully 15 With.

Even after the transition 14 from the roll shell 11 Tangentially thrown off water causes a guided by the compressed air entrained water to the gutter 15 out.

In addition, this compressed air generates in the guide channel 16 in the area of the deflector bar 4 as well as in the gusset itself a negative pressure, that of the deflector bar 4 stripped and thrown to this water in the guide channel 16 dissipates in the direction of rotation.

To protect the environment from water fog is the gully 15 with an enclosure 6 connected, extending over a substantial peripheral area of the press roll 9 extends. This enclosure 6 has an air suction device 7 which not only suppresses the propagation of water mist, but also prevents overpressure due to the compressed air supply.

At the inlet of the roll mantle 11 in the press nip is a water scraper 12 that the roll mantle 11 finally drain. Because of the deflection of the press roll 9 is the water scraper 12 in a peripheral region perpendicular to the press plane 17 of the pressing element 10 ,

Claims (12)

Press arrangement for dewatering a paper, board, tissue or other fibrous web ( 1 ) in a machine for the production and / or refinement thereof, consisting of one, of two press rolls ( 9 . 13 ), extended press nip the press plane ( 17 ) forms an angle of maximum 45 ° with the horizontal and by the next to the fibrous web ( 1 ) at least one endless circulating dewatering belt ( 2 ), with the dewatering belt ( 2 ) coming in contact press roll ( 9 ) a flexible roll shell ( 11 ) possessed by a pressing element ( 10 ) with concave pressing surface to the cylindrical counter-pressure roller ( 13 ) is pressed, after the press nip in the gusset between the press roll ( 9 ) and the drainage tape ( 2 ) substantially along the press roll ( 9 ) extending gutter ( 15 ) is present for receiving the thrown off water whose gland-side boundary wall ( 5 ) with the press roll ( 9 ) a guide channel ( 16 ), characterized in that the diameter of the press roll ( 9 ) smaller than the diameter of the counter-pressure roller ( 13 ) and the gusset-side boundary wall ( 5 ) far from the press roll ( 9 ) and extends only so far in the direction of rotation that after the transition ( 14 ) from the convex to the concave shape of the roll shell jacket ( 11 ) tangentially thrown water unhindered over this boundary wall ( 5 ) into the gully ( 15 ). Press arrangement according to claim 1, characterized in that the diameter of the press roll ( 9 ) is at least 10% smaller than the diameter of the counter-pressure roller ( 13 ). Press arrangement according to claim 1 or 2, characterized in that the diameter of the press roll ( 9 ) at least 25% smaller than the diameter of the counterpressure roller ( 13 ). Press arrangement according to one of the preceding claims, characterized in that the diameter of the press roll ( 9 ) is at least 40% smaller than the diameter of the counter-pressure roller ( 13 ). Press arrangement according to one of the preceding claims, characterized in that at the gland end of the gully ( 15 ) substantially along the press roll ( 9 ) extending deflector bar ( 4 ), which is the beginning of the guide channel ( 16 ) with the press roll ( 9 ). Press arrangement according to claim 5, characterized in that the deflector strip ( 4 ) with the dewatering belt ( 2 ) is in contact or has a small distance to this. Press arrangement according to claim 5 or 6, characterized in that the deflector strip ( 4 ) has an acute-angled, projecting into the gusset end. Press arrangement according to one of claims 5 to 7, characterized in that between deflector strip ( 4 ) and the boundary wall ( 5 ) of the gully ( 15 ) Compressed air in the guide channel ( 16 ) is blown in the direction of rotation. Press arrangement according to one of the preceding claims, characterized in that in the collecting area of the gutter ( 15 ) an air suction device ( 7 ) is available. Press arrangement according to one of the preceding claims, characterized in that the transition ( 14 ) extends over at most 20 °, preferably at most 15 °, in particular over a maximum of 10 ° of the roll circumference. Press arrangement according to one of the preceding claims, characterized in that the press plane of the press rolls ( 9 . 13 ) runs horizontally. Press arrangement according to one of the preceding claims, characterized in that the press plane of the press rolls ( 9 . 13 ) forms with the horizontal an angle of a maximum of 30 °, preferably a maximum of 15 °.