WO1991000388A1

WO1991000388A1 - Improved dewatering system with vortex valve

Info

Publication number: WO1991000388A1
Application number: PCT/US1990/003546
Authority: WO
Inventors: Thomas Stephen Fielding; Charles Richard Mc Call
Original assignee: Albany International Corp.
Priority date: 1989-06-23
Filing date: 1990-06-21
Publication date: 1991-01-10
Also published as: GB2233473A; BR9006817A; GB9013894D0; EP0433434A4; EP0433434A1; AU6030890A; GB8914438D0; CA2033210A1; FI905016A0; JPH04500395A

Abstract

A dewatering system is disclosed in papermaking machine for removing water from a web (P) such as a paper sheet made of pulp. The drainage system includes a vacuum or suction box (1), a separator (3) for separating solids and/or liquids from the drainage, and vortex valve (6) connecting the separator (3) to vacuum (5). Advantageously, the vortex valve (6) operates to maintain a substantially constant pressure at the separator outlet independently of the gas flow through the valve (6).

Description

IMPROVED DEWATERING SYSTEM WITH VORTEX VALVE

BACKGROUND OF THE INVENTION Field of Invention

This invention pertains to an improved web dewatering system for the papermaking industry, and more particularly to a dewatering system for a web or the like by applying vacuum thereto through a vortex valve. Description of the Prior Art

In conventional suction pipe systems in the papermaking industry a vacuum applying means such as a suction pipe or box with one or more slots is positioned in alignment with a web. The suction pipe is positioned so that the web passes over the slot and when the appropriate pressure differential is produced the web will be dewatered, the water being drawn into the suction pipe and directed to an appropriate collection location. A separator is used to separate water and solids from air in the system and the air is exhausted through a mechanical valve which may be operated either remotely or manually. One such system is disclosed in commonly assigned U.S. Patent No. 4,308,077.

One common problem with the prior art systems has been that the mechanical valve had moving parts which were subject to excessive wear and tear and this would break down. A further problem with mechanical valves has been that the suction pipe removed solid, semi- solid and liquid matter from the web and if the separator failed to remove all these impurities from the air in the system, these impurities tended to clog the valve and render it inoperable. Yet another disadvantage of the prior art system was that the mechanical valve could not be controlled precisely and could not be adapted to sophisticated, precise control schemes.

OBJECTIVES AND SUMMARY OF THE INVENTION In view of the above-mentioned disadvantages of the prior art, an objective of the present invention is to provide a dewatering system using a vortex valve whereby the need for the mechanical valve with its moving parts is eliminated.

A further objective of the invention is to provide a dewatering system with a vortex valve which is responsive and easily controlled to permit the use of sophisticated control schemes.

Other objectives and advantages of the invention shall become apparent from the following description of the invention. Briefly, a dewatering system constructed in accordance with the invention includes a suction pipe, a vacuum box, or other vacuum application means of removing water from a web by applying vacuum thereto. The term web is used generically to cover either the pulp from which a paper sheet is formed, or a felt used for drying a paper sheet. The vacuum necessary for this operation is applied to the vacuum application means through a control valve and separator means for separating solids and liquids from the gas suctioned through the web. Advantageously, the control valve comprises a vortex valve.

A vortex valve, known also as a vortex amplifier, is a fluidic device which does not have moving parts and seals prone to wear and corrosion during use, and it comprises a vortex chamber through which a main flow passes radially to emerge at an axial outlet. The main flow can be regulated and controlled by a control flow introduced tangentially into the vortex chamber, as disclosed for example in European Patent Specification No. 0089186 (corresponding to U.S. Patent No. 4,422, 476) . Importantly, the vortex valve provides a uniform pressure at the separator gas outlet substantially independently of the gas flow exiting from said separator.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be described further, by way of example, with reference to the accompanying drawing, in which:

Figure 1 is a schematic arrangement of a dewatering system for papermaking constructed in accordance with the invention;

Figure 2 discloses a first alternate embodiment of the invention;

Figure 3 discloses a second alternate embodiment of the invention; and

Figure 4 discloses a third alternate embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, in Figure 1, a vacuum box or suction pipe 1 in a papermaking machine is used to dewater a web P traveling over the box. The box communicates through conduit 2 with a separator 3. One end of the separator 3 drains into a vessel 4 and the opposite end of the separator 3 is connected to a vacuum header 5 by way of a vortex valve or vortex amplifier 6. The vortex valve or amplifier is basically a chamber having supply, outlet and control ports. One such vortex valve or amplifier is disclosed in European Patent Specification No. 0089186. In the present arrangement the outlet from the vortex valve 6 is connected to the vacuum header 5. The separator 3 is connected to the inlet of the vortex valve 6. The control port is connected to conduit 8 which in the embodiment of Figure 1 is open to the atmosphere. A vacuum gauge 9 can be included in the flow path from the separator 3 to the inlet of the vortex valve 6.

In use, web P passes over the vacuum box 1 during papermaking. Water drains into the box 1 and the water will contain some other drainage such as pulp which can clog and block conventional valves hitherto used to control the level of vacuum in the box 1. In the present invention, the water containing drainage is drawn along conduit 2 into the separator 3 to drain into the vessel 4. A fraction of the solid pulp particles can be drawn by the suction of the header 5 into the vortex valve 6. However, unlike a conventional valve, the vortex valve has relatively large orifices with no moving parts and hence the possibility of blockage by the solid particles and consequent performance degradation is reduced considerably. Valve 6 is designed to maintain a non-adjustable, relatively constant pressure at the outlet of separator 3.

If desired, the pressure set by valve 6 can be adjusted by including an adjustable valve 10 in conduit 8 as shown in Figure 2. This valve 10 can be adjusted manually by an operator to set the operating point of valve 6.

Alternatively, as shown in Figure 3 the valve 10 can be a motorized valve which adjusts air flow to the control port of the vortex valve 6 in response to signals from a remote location. For example, a pressure transducer 11 may be provided to measure the pressure upstream of valve 6. This pressure is then supplied to a control unit 12 to control the motorized valve 10.

Lastly, it may be desirable to apply positive pressure to valve 6, for example, by coupling an air source such as a fan 7 to conduit 8, as shown in Figure 4. It should be understood that while the drainage system was described as operating in the forming section of the papermaking machine, it will be equally as effective in the pressing section, for example, for dewatering a felt.

Obviously, other modifications may be made to the invention without departing from its scope as defined in the appended claims.

Claims

What is Claimed is:

1. In a papermaking machine, a dewatering system comprising: vacuum applying means for removing water from a web; separator means for removing drainage from said vacuum applying means and for substantially separating liquids and solids from said drainage; a source of vacuum for applying vacuum to said separator means; and vortex valve means connecting said source of vacuum to said separator means, said vortex valve means being constructed and arranged to provide a uniform pressure to said separator means independently of the gas flowing therethrough.

2. The system of claim 2 wherein said vortex valve means includes an control port.

3. The system of claim 2 wherein said control port is open to atmosphere.

4. The system of claim 2 wherein said control port is connected to a control valve, said control valve being constructed and arranged to adjust the pressure at said separator means.

5. The system of claim 4 wherein said control valve is open to atmosphere.

6. The system of claim 4 further comprising control means for adjusting said control valve.

7. The system of claim 6 wherein said control means includes a pressure sensing means for sensing •pressure upstream of said vortex valve, and control apparatus for controlling said control valve in accordance with said sensed pressure.

8. The system of claim 2 further comprising a source of air for applying positive pressure to said control port.

9. The system of claim 8 further comprising a control valve connected between said source of air and said control port for adjusting said positive pressure.

10. The system of claim 8 wherein said source of air comprises a fan.