APPARATUS AND METHOD FOR PROCESSING WHITE WATER IN A PAPER MACHINE

• US 20200131704A1
• Filed: 12/23/2019
• Published: 04/30/2020
• Est. Priority Date: 05/27/2015
• Status: Active Grant

• Current Assignee: Valmet AB
• Original Assignee: Valmet AB
• Inventors: Engqvist, Elin, Videgren, Leif
• Granted Patent: US 11,028,533 B2
• Time in Patent Office: Days
• CPC Class Codes: D21D 5/26 De-aeration of paper stock
• CPC Class Codes: D21F 1/66 Pulp catching, de-watering, or recovering; Re-use of pulp-water

Abstract

Aspects provide for a Whitewater processing system suitable for managing an ejected Whitewater spray during operation of a paper or board making machine. A de-air system may provide for improved removal of air from the Whitewater. A calming system may reduce turbulence in a liquid flow, reducing turbulence in the flume. The de-air system and calming system may be disposed together or separately. Certain aspects may be implemented with a turbine (e.g., used to generate electricity from the Whitewater spray). Some aspects may provide for improved handling of variable spray velocities.

Claims

1. A de-air system for processing a whitewater spray ejected through a forming wire of a paper machine having a frame and a machine direction, the de-air system comprising:

channels defined by walls shaped to direct a portion of the whitewater spray away from the machine direction, the channels open at entrances proximate to the forming wire and terminating at liquid outlets of the de-air system; and

air outlets providing for air evacuation from the channels;

wherein the channels are configured such that at least one of;

a) between the respective entrances and liquid outlets of the de-air system, and excluding the air outlets, there is no substantial fluid communication between the channels;

b) the walls comprise side walls for which a majority of the side walls is within 10 degrees of vertical;

or

c) less than 5% of a cross-sectional area of the channels is intersected by a free upstream end of a part.

2. The de-air system of claim 1, wherein the channels are configured such that:

a) between the respective entrances and liquid outlets of the de-air system, and excluding the air outlets, there is no substantial fluid communication between the channels; and

b) the walls comprise side walls for which a majority of the side walls is within 10 degrees of vertical.

3. The de-air system of claim 2, wherein the channels are configured such that:

c) less than 5% of a cross sectional area of the channels is intersected by a free upstream end of a part.

4. The de-air system of claim 1, wherein at least one air outlet is disposed in a ceiling of its respective channel.

5. The de-air system of claim 4, wherein each channel includes an air outlet, and each air outlet disposed in a ceiling of its respective channel.

6. The de-air system of claim 4, wherein at least one air outlet is located, with respect to the machine direction, closer to an upstream wall than to a downstream wall of its respective channel.

7. The de-air system of claim 1, wherein the channels are configured such that less than 1% of a cross-sectional area of the channels is intersected by a free upstream end of a part

8. The de-air system of claim 1, wherein the walls comprise side walls for which greater than 80% of the side walls is within 5 degrees of vertical.

9. The de-air system of claim 1, further comprising first and second air outlets in first and second channels, wherein the first and second air outlets have different sizes.

10. The de-air system of claim 1, wherein at least one air outlet has an adjustable size.

11. The de-air system of claim 1, further comprising a roof drain configured to collect mist or water external to the de-air system, the roof drain comprising:

a roof;

a gutter; and

a drain.

12. A paper machine configured to fabricate at least one of paper, board, and tissue, the paper machine comprising the de-air system of claim 1.

13. The paper machine of claim 12, further comprising a turbine disposed between the forming wire and the de-air system, the turbine configured to recover energy from the whitewater spray.

14. The paper machine of claim 13, wherein the entrances of the de-air system comprise one or more leading edges shaped to match a corresponding shape of the turbine.

15. The paper machine of claim 12, wherein the air outlets are disposed outside the frame of the paper machine.

16. The paper machine of claim 12, wherein an inner portion of the de-air system is disposed inside the frame of the paper machine, and an outer portion comprising the liquid outlets of the de-air system is disposed outside the frame.

17. The de-air system of claim 1, further comprising a calming station configured to receive liquid from the liquid outlets of the de-air system, the calming station comprising:

a liquid inlet configured to receive the liquid; and

a calming station liquid outlet configured to convey the liquid out of the calming station.

18. A paper machine configured to fabricate at least one of paper, board, and tissue, the paper machine comprising the de-air system of claim 17.

19. The de-air system of claim 17, wherein the calming station further comprises a gate disposed between the liquid inlet and the calming station liquid outlet, such that the liquid may flow through and/or around the gate, the gate the gate comprising an adjustable gate configurable among two or more different positions that alter the flow of the liquid in different ways.

20. The de-air system of claim 17, wherein the calming station further comprises a gate disposed between the liquid inlet and the calming station liquid outlet, such that the liquid may flow through and/or around the gate, the gate having a pattern of one or more holes, bars, slats, ridges, grooves, and/or pitches configured to modify the flow of liquid through and/or around the gate, wherein the pattern comprises a first portion having a first pattern and a second portion having a second pattern.

21. A method for removing air from a whitewater spray ejected through a forming wire of a paper machine, the method comprising:

providing the paper machine of claim 12;

operating the paper machine;

evacuating a gas phase from the air outlets of the de-air system; and

conveying a liquid phase out of the liquid outlets of the de-air system.