Method and apparatus for producing a fibre web

Patent metadata

Field	Value
Publication number	US-10954632-B2
Application number	US-201716339476-A
Country	US
Kind code	B2
Filing date	Oct 4, 2017
Priority date	Oct 5, 2016
Publication date	Mar 23, 2021
Grant date	Mar 23, 2021

Abstract

According to an example aspect of the present invention, there is provided an apparatus and a method comprising a forming section for feeding an aqueous furnish of fibres on a moving surface to form a shape of a product and a pressing and heating section for removing water from the shaped product received from the moving surface. The pressing and heating section comprises a felt and metal belt that are set to run against each other for receiving the furnish from the moving surface and heating elements for heating the web in at least two pulses including at least one first pulse wherein the product is pressed for at least 10-200 ms on a first pressure and at least one second heating and smoothing pulse wherein the product is heated at least for 10-200 ms on a pressure that is higher than the first pressure, and at least one of the surfaces pressing the product being the smooth metal belt.

First claim

The invention claimed is:

1. An apparatus for forming a fiber web comprising:
a forming section for feeding an aqueous fiber furnish on a moving surface to form a fiber web; and
a pressing and heating section for removing water from the formed web received from the moving surface; wherein the pressing and heating section comprises a felt and a smooth metal belt that are set to run against each other for receiving the formed web from the moving surface,
heating elements for heating the web in at least two pulses including at least one first pulse wherein the web is heated and pressed for at least 10-200 ms on a first pressure and at least one second heating and smoothing pulse wherein the web is heated at least for 10-200 ms on a pressure that is higher than the first pressure, wherein at least one of the surfaces pressing the web is the smooth metal belt,
a forming apparatus having a narrowing nip formed of two moving permeable fabrics and a feeding apparatus comprising at least one guide surface that forms a gap together with at least one of the moving permeable fabrics, and at least one feeding opening for feeding furnish to the narrowing nip, and
a first feeding slot for feeding the furnish on the nip of the moving permeable fabrics as one central first flow to form a central layer of the web, second feeding slots for feeding the furnish as two secondary flows perpendicular to the moving permeable fabrics on both sides of the central flow to form second layers of the web, and third feeding slots for feeding two tertiary flows having speed lower than the moving permeable fabrics and being fed on both sides of the central flow, the feeding points of the second slots being upstream of the first slot and feeding points of the third slots being upstream to the second slots.

2. The apparatus according to the claim 1 , further comprising at least one vacuum box at the side of at least one of the fabrics that is opposite to the side facing the narrowing nip and the feeding apparatus.

3. The apparatus according to claim 1 , wherein the heating elements are arranged to heat the web to a temperature reaching at least 80° C. on at least one surface of the web at the end of the last pulse.

4. The apparatus according to claim 1 , comprising heating and pressing elements for heating the web in pulses comprising a first pulse of 10-200 ms at 0.01±0.01 MPa, a second pulse of 10-200 ms at 0.1±0.1 MPa, a third pulse of 10-200 ms at 0.1-1 MPa, and a fourth pulse of 10-100 ms at 0.1-10 MPa.

5. The apparatus according to claim 1 , wherein the heating elements for heating the web and the smooth metal belt comprise at least one of the following: a heated roll against the web and/or smooth metal belt, a heater on the back side of the smooth metal belt, a heater on the web side of the smooth metal belt.

6. The apparatus according to claim 1 , wherein the felt and smooth metal belt are arranged to be pressed against each other in order to provide the first pulse.

7. The apparatus according to claim 1 , wherein the web is arranged to run around at least one heated roll supported by the smooth metal belt for providing a second pulse.

8. The apparatus according to claim 1 , wherein the web is arranged to run around more than one heated roll supported by the smooth metal belt for providing a second pulse or pulses.

9. A method for producing fiber webs, comprising
a forming step for feeding an aqueous furnish of fibers on a moving surface to form a shape of a web; and
a pressing and heating step for removing water from the shaped web received from the moving surface; wherein
at the pressing and heating step the shaped web is received between a felt and smooth metal belt that are set to run against each other; and
the web is heated by heating elements between the felt and the smooth metal belt in at least two pulses including at least one heating pulse wherein the web is pressed for at least 10-200 ms on a first pressure and at least one heating and smoothing pulse wherein the web is heated at least for 10-200 ms on a pressure that is higher than the first pressure, and at least one of the surfaces pressing the web being the smooth metal belt, wherein
a narrowing nip is formed of two moving permeable fabrics and furnish of at least water and fibers is fed into the nip of the fabrics by a feeding apparatus comprising at least one guide surface that forms a gap together with at least one of the fabrics, and
the furnish is fed on the nip of the fabrics as one central first flow to form a central layer of the web-like web, as two secondary flows perpendicular to the moving permeable fabrics on both sides of the central flow to form second layers or the web and as two tertiary flows having speed lower than the fabrics and being fed on both sides of the central flow, the feeding points of the second flows being upstream of the first flow and feeding points of the third flows being upstream to the second flows.

10. The method according to claim 9 , wherein the temperature of the web entering to the pressing and drying step is gradually increased from incoming temperature of 30-60° C. to a drying temperature of 80-100° C.

11. The method according to claim 9 , wherein the furnish is fed on the nip of the moving permeable fabrics as a mixture of foam and fibers.

12. The method according to claim 9 , wherein water is removed from furnish by suction through the moving permeable fabrics.

13. The method according to claim 9 , wherein the felt and the smooth metal belt are arranged to be pressed against each other in order to provide the first pulse.

14. The method according to claim 9 , wherein the web is arranged to run around at least one heated roll supported by the smooth metal belt for providing a second pulse.

15. The method according to claim 9 , wherein the web is arranged to run around at more than one heated roll supported by the smooth metal belt for providing a second pulse or pulses.

16. The method according to claim 9 , wherein the web is heated by the heating elements to a temperature reaching at least 80° C. on at least one surface of the web at the end of the last pulse.

17. The method according to claim 9 , further comprising heating and pressing the web in pulses comprising a first pulse of 10-200 ms 0.01±0.01 MPa, a second pulse of 10-200 ms 0.1±0.1 MPa, a third pulse of 10-200 ms 0.1-1 MPa, and a fourth pulse of 10-100 ms 0.1-10 MPa.

18. The method according to claim 9 , wherein the side of the web that is against the smooth metal belt is heated to a temperature of about 80-110° C. and the felt side about 50-90° C. at the narrowing nip.

19. The method according to claim 9 , wherein the infeed DMC of the furnish is 0.1-3%, the DMC of the web is 20-30% after forming and 40-65% after the pressing and heating step.

Assignees

• Teknologian Tutkimuskeskus Vtt Oy

Inventors

• Pihko Riku
• Lehmonen Jani
• Rökman Kay

Classifications

• D21F11/00

  Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines · CPC title

• D21F9/00

  Complete machines for making continuous webs of paper · CPC title

• D21F5/04

  on two or more drying cylinders · CPC title

• D21F3/04

  Arrangements thereof · CPC title

• D21F3/02

  Wet presses · CPC title