Vacuum box, belt filter, methods for servicing a vacuum belt filter, method for liquid-solid separation of a slurry, and filter element

Patent metadata

Field	Value
Publication number	US-10653982-B2
Application number	US-201615771540-A
Country	US
Kind code	B2
Filing date	Nov 2, 2016
Priority date	Nov 3, 2015
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

A vacuum belt filter including a belt with a plurality of vacuum boxes, filter means being arranged to the vacuum boxes, drive means for moving the belt, and a suction station for creating an underpressure to the vacuum boxes at the suction station. In order to enable liquid-solid separation at low energy costs and long service interval of the vacuum belt filter, the filter means is in the form of a capillary filter, each vacuum box being provided with such a filter and each vacuum box being provided with an outlet having a check valve enabling a fluid flow from the inside space of the vacuum box to the outside of the vacuum box for creating an underpressure in the vacuum box when the suction station is connected to the vacuum box.

First claim

The invention claimed is:

1. A vacuum box configured to form a part of an endless belt of a vacuum belt filter, the vacuum box comprising:
a vacuum body defining an inside space configured to receive a filtrate;
a capillary filter disposed on the vacuum body to form an upper surface of the vacuum box, the capillary filter being configured to collect residue in the form of a filter cake on the upper surface of the vacuum box; and
an outlet coupled to the vacuum body and having a check valve configured to enable a fluid flow from the inside space of the vacuum body to an outside of the vacuum body for creating an underpressure in the vacuum body, the vacuum body being configured to maintain the underpressure within the inside space without being connected to a vacuum source, and the check valve being configured to prevent a fluid flow to the inside space, wherein the check valve includes a blocking member disposed in a blocking position when there is underpressure within the inside space of the vacuum body, enabling maintaining the underpressure in the inside space of the vacuum body when the vacuum body is not connected to a vacuum source, and opened from the blocking position when the vacuum body is connected to the vacuum source to enable the fluid flow from the inside space of the vacuum body to the outside of the vacuum body for creating the underpressure in the vacuum body.

2. The vacuum box according to claim 1 , wherein the check valve of the outlet comprises a mechanical actuator for closing the blocking member of the check valve.

3. The vacuum box according to claim 1 , wherein a pore size of the capillary filter is 0.03 μm to 5 μm.

4. The vacuum box according to claim 1 , wherein the capillary filter is a ceramic filter.

5. The vacuum box according to claim 1 , wherein the vacuum box is provided with an inlet for feeding wash fluid to the inside space of the vacuum box and on the clean side of the capillary filter.

6. The vacuum box according to claim 5 , wherein the inlet comprises a check valve comprising a mechanical actuator for resiliently biasing a blocking member of the check valve toward a closed position to inhibit fluid from flowing into the inside space via the inlet, the mechanical actuator keeping the blocking member of the check valve and the check valve in a closed position when a pressure acting from the outside of the vacuum box against the blocking member and against a force of the mechanical actuator is smaller than the sum of the force of the mechanical actuator and the pressure acting from the inside of the vacuum box on the blocking member wherein the check valve opens when the pressure acting from the outside of the vacuum box against the blocking member and against the mechanical actuator is bigger than the sum of the force of the mechanical actuator and the pressure acting from the inside of the vacuum box on the blocking member.

7. The vacuum box according to claim 1 , wherein the vacuum body includes:
a bottom having first and second short sides and first and second long sides, the outlet extending from the bottom;
first and second opposing long walls extending upwardly from the respective first and second long sides of the bottom; and
first and second opposing end walls extending upwardly from the respective first and second short sides of the bottom, wherein the capillary filter, the bottom, the first and second long walls, and the first and second end walls together define the inside space.

8. The vacuum box according to claim 7 , wherein the first and second end walls taper towards the bottom.

9. The vacuum box according to claim 7 , further comprising first and second lateral shields extending upwardly from the respective first and second end walls and terminating above the upper surface of the vacuum box.

10. The vacuum box according to claim 7 , wherein the capillary filter is suspended above the bottom such that the inside space is defined between the capillary filter and the bottom.

11. The vacuum box according to claim 7 , wherein the capillary filter includes:
a first permeable filter surface; and
a second surface opposite the first permeable filter surface.

12. The vacuum box according to claim 11 , further comprising a replaceable filter element including:
the capillary filter; and
a first support structure supporting the second surface of the capillary filter.

13. The vacuum box according to claim 12 , wherein the replaceable filter element further includes an intermediary layer permanently attached to the second surface of the capillary filter for coupling the first support structure to the second surface.

14. The vacuum box according to claim 13 , further comprising a second support structure fixed to a top of each of the first and second long walls and the first and second end walls.

Assignees

• Outotec Finland Oy

Inventors

• Vänttinen Kari
• Illi Mika
• Ekberg Bjarne

Classifications

• B01D33/15

  with rotary plane filtering surfaces · CPC title

• B01D29/50

  with multiple filtering elements, characterised by their mutual disposition (B01D29/39 takes precedence) · CPC title

• B01D33/056 Primary

  Construction of filtering bands or supporting belts, e.g. devices for centering, mounting or sealing the filtering bands or the supporting belts · CPC title

• B01D33/155

  the filtering surface being parallel to the rotation axis · CPC title

• B01D29/09 Primary

  with filtering bands, e.g. movable between filtering operations · CPC title