WO2017173161A1

WO2017173161A1 - Rotating belt filter automated self-cleaning assembly

Info

Publication number: WO2017173161A1
Application number: PCT/US2017/025169
Authority: WO
Inventors: Cornelius J. STRAIN
Original assignee: Nexom (Us), Inc.
Priority date: 2016-04-01
Filing date: 2017-03-30
Publication date: 2017-10-05

Abstract

Systems and methods are described for cleaning a sprayer or other cleaning device used to spray a fluid against a filtration medium such as a rotating belt filter. The systems and methods can be used with the cleaning device in-place, optionally without taking the filter out of commission. The cleaning may involve flushing the inside of the cleaning device with a fluid, physically scrubbing or abrading the inside of the cleaning device, or both. In some examples a brush rotates inside of the cleaning device. The systems and methods can be operated manually or partially or completely automated.

Description

ROTATING BELT FILTER AUTOMATED SELF-CLEANING

ASSEMBLY

TECHNICAL FIELD

[0001] The disclosure is related to rotating belt filters or other similar screening devices, and in particular to systems and methods for cleaning them. Such filters can be used, for example, to provide solid-liquid separation within the water, wastewater, mining, agricultural, oil & gas, manufacturing and other industries.

BACKGROUND

[0002] International Publication Number WO 94/26387, Apparatus for Cleaning Endless Filtering Bands, describes a cleaning device for endless filter belts. The filter belt passes over a series of rollers. Part of the filter belt is located within a container of contaminated water. Another part of the filter belt runs generally horizontally with solids retained on the filter belt hanging downwards. This part of the filter belt is provided with one or more tubes inside the belt traversing across the width of the belt. The tubes have holes or slots directed downwards toward the filter belt for blasting a cleaning fluid through the filter belt. The cleaning fluid may be pressurized air or water.

[0003] International Publication Number WO 01/56681 , Cleaning Device for Waste Water, describes an endless belt that is cleaned with an air knife. The air knife is a tube traversing across the inside of the belt. The tube has a continuous slit traversing the width of the belt to form the air knife and direct it towards the belt.

[0004] International Publication Number WO 2014/008512, Enhanced Momentum Cleaning Device for Rotating Belt Screens and Filters, describes cleaning devices for a filter belt. In one example, the cleaning device is a spray- bar with nozzles, injectors or a slot configured to direct a fluid stream through the belt. The fluid may be water or a mixed-phase (i.e. air and water) fluid. The fluid may be provided continuously or periodically.

[0005] The publications described above are incorporated herein by reference.

SUMMARY

[0006] Cleaning devices such as spray bars used for cleaning the belts of rotating belt filters are prone to fouling due, for example, to scale-forming contaminants and debris in the fluid being used for cleaning. When fouling occurs in conventional cleaning devices, the filter must be taken out of commission and disassembled to remove the cleaning device for de-fouling, cleaning or replacement. In some cases, since the cleaning device is located within the filter belt, a crane or forklift is required to remove a cartridge containing the filter belt and cleaning device from the filtration unit before the cleaning device can be removed for inspection, maintenance or replacement.

[0007] This specification describes systems and methods to clean the cleaning device in-place, optionally without taking the filter out of commission. The cleaning device may be de-scaled or have particulate foulants removed or both. In one example, the cleaning device is flushed with a fluid flowing along the length of the cleaning device. In another example, the inside of the cleaning device is physically scrubbed. Fluid flushing and physical scrubbing can optionally be used in combination. In some examples a brush scrubs the inside of the cleaning device.

[0008] The system can be manually operated. Alternatively, the system can include powered devices such as motors, pumps or valves, and optionally one or more sensors or timers, linked to a controller to allow for automated or semi- automated operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a sectional view of a filtration unit with an endless belt and a cleaning device.

[0010] Figure 2 is a front sectional view of the cleaning device of Figure 1 .

[0011] Figure 3 is a side sectional view of the cleaning device of Figure 2.

[0012] Figure 4 is a front sectional view of an alternative cleaning device of Figure 1.

DETAILED DESCRIPTION

[0013] A rotating belt filter, alternatively called a rotating belt sieve, includes an enclosure or channel for receiving a flow of water containing suspended solids. An endless (i.e. looped) belt is positioned within the enclosure such that at least some of the water must pass through the belt before leaving the enclosure. One optional use of a rotating belt filter is to provide primary treatment by separating suspended solids from wastewater. In some examples, a filter belt passes over a series of rollers that are configured to compose a mounting cartridge for the belt. Influent water can flow into the enclosure perpendicular or tangential to the rollers.

[0014] Cleaning devices, for example in the form of sprayers, air knives or other fluid distribution assemblies, are used to remove solids and possibly other contaminants to from the belt. The cleaning device may be mounted within the cartridge or elsewhere within the filter housing. The cleaning device is configured and oriented so as to spray a fluid at or through the belt.

[0015] A cleaning device as described herein has one or more brushes internal or external to the cleaning device. The one or more brushes may be aligned with the length of the cleaning device. The one or more brushes my have, for example, bristles, abrasive pads, abrasive fabric strips, or other appropriate scrubbing or abrasive media. [0016] In one example, the cleaning device is a spray bar with nozzles dispersed along the bar. A brush system is provided inside of the spray bar. The brush system typically operates intermittently, but could alternatively operate continuously. The brush system extends along at least a portion of the length of the bar, preferably including the nozzles. The brush system may rotate on a shaft extending through at least part of the spray bar. The shaft can be turned manually or the shaft can be connected to a motor. The motor is optionally connected to a controller. The system can be automatic, with the controller monitoring a signal such as pressure inside the spray bar or a timer, to determine when to operate the motor. Alternatively, the system may be semi-automatic. For example, an operator may determine when the cleaning device needs to be cleaned by reviewing meter and then instruct the controller to operate a predetermined cleaning protocol.

[0017] The cleaning device preferably has an opening with a valve, optionally connected to the controller, for venting fluid from the cleaning device other than though the nozzles. The opening can be at an end of the cleaning device opposite from where fluid to be sprayed through the nozzles enters the cleaning device. The opening thereby allows fluid to be flushed through the cleaning device to remove foulants released by the brush system to be removed from the cleaning device other than through the nozzles. The cleaning device can be flushed while or after the brush system is operated. Flushing the cleaning device reduces the possibility that dislodged scale or foulants plug the orifices of the cleaning device or become lodged in the filter belt.

[0018] The cleaning device can be flushed with water, air, or a two-phase flow. Optionally, the flushing fluid can include a solvent, anti-scalant, surfactant, or other cleaning agent to enhance the effectiveness of the brush or provide independent chemical cleaning. For sites with multiple filters, a centralized pump station can be used to provide flushing fluid to the multiple filters. For large multi- filter installations it will be preferable to automate the cleaning cycles to reduce operator effort. [0019] Figure 1 is a schematic sectional view of a rotating belt filter 500. The filter 500 includes a filter belt 502 positioned in an enclosure 508. The filter belt 502 may be mounted on a removable cartridge that includes a frame and rollers for supporting the filter belt 502. The enclosure 508 has a fluid inlet 550, a filtered fluid outlet 554, and an overflow trough 552.

[0020] A cleaning device 510 is located, for example, inside the filter belt 502. The cleaning device 510 shown has its nozzles close to or adjacent the inside of the belt 502. The cleaning device 510 is located over a solids handling system 536. The solids handling system 536 has an auger or other suitable device to remove solids that are dislodged from the belt 502 by the cleaning device 510. The cleaning device 510 may be a tube, for example, with a generally square or round cross-section. The cleaning device 510 may have, for example, one long slit, a series or holes or slits, or a series of nozzles to spray a fluid against the belt 502.

[0021] An example of a cleaning device 510 is shown in Figures 2 and 3. In this example, the cleaning device 510 has a cylindrical body 518 with a series of nozzles 516. A shaft 512 extends through the length of the body 518 on its longitudinal axis. The shaft 512 has a set of brushes 514 mounted to it. The brushes 514 shown are located over nozzles 516. Optionally, brushes 514 could be wider such that they cover nozzles 516 and part of the body 518 to the side of the nozzles 516. Optionally, brushes 514 may substantially cover the body 518 or at least be continuous between the first and last nozzle 516. The configuration of the brushes 514 is partially open so that fluids can flow past the brushes 514. The shaft 512 may be supported on bearings 520. A portion of the shaft 512 can extend outside of the body 518 to allow the shaft 512 to be turned. Alternatively, blades can be attached to the shaft 512 so that it turns when a fluid is flushed through the body 518 from an inlet 522 to an outlet 524.

[0022] Figure 4 illustrates an alternative cleaning device 510'. The alternative cleaning device 510' differs from the cleaning device 510 of Figures 2 and 3 primarily in that the shaft 512 is provided by a flexible cable rather than a rigid rod.

[0023] Specific embodiments of the invention have been described herein for purposes of illustration, but various modifications may be made without deviating from the scope of the invention. For example, a brush could be provided in another configuration. A brush could also move in a different manner, for example by oscillating rotationally or longitudinally or both, in place of or in addition to rotating. Scrubbing might also be provided by spherical brushes or abrasive balls entrained in a fluid flowing through the inside of the cleaning device. A flushing may be pulsed fluid or heated.

[0024] Although the invention has been described for use with a rotating belt filter, the invention may be adapted for use with a cleaning device for a drum filter, disc filter or other filter having a screening surface that air or water is sprayed against.

[0025] Optionally, a system or method of cleaning a cleaning device may be combined with pre-screening of the filter cleaning fluid before it passes through the cleaning device. For example, water or air used to clean a filter can be pre- filtered to remove some particulates that might otherwise plug orifices in a cleaning device.

[0026] Optionally, the cleaning device can be accessed through a removable access plate that allows the cleaning device to be removed while the filter belt remains installed in its enclosure. Although the systems and methods described herein inhibit fouling of the cleaning device, it may still be useful to access the cleaning device periodically without removing a belt cartridge from its enclosure.

Claims

CLAIMS I/We claim:

1 . A filtration device comprising: an endless filter belt; a cleaning device adapted to spray a fluid against the belt; and, a brush within the cleaning device.

2. The filtration device of claim 1 wherein the brush is movable.

3. The filtration device of claim 2 wherein the brush rotates.

4. The filtration device of any preceding claim wherein the brush comprises bristles.

5. The filtration device of any preceding claim wherein the brush comprises an abrasive surface.

6. The filtration device of any preceding claim wherein the brush comprises a shaft extending along the length of the cleaning device, wherein the shaft is rotatable.

7. The filtration device of claim 6 comprising a motor to rotate the shaft.

8. The filtration device of claim 7 comprising a controller in communication with the motor.

9. The filtration device of any preceding claim wherein the cleaning device has a flushing fluid outlet.

10. A method of cleaning a fluid sprayer comprising scrubbing the inside of the fluid sprayer, flushing the inside of the fluid sprayer, or both.

1 1 . The method of claim 10 comprising scrubbing the inside of the fluid sprayer.

12. The method of claim 1 1 comprising rotating a brush inside the fluid sprayer.

13. The method of any preceding claim comprising flushing the inside of the fluid sprayer while or after moving a brush inside the fluid sprayer.

14. The method of any preceding claim performed according to a predetermined schedule.

15. The method of any preceding claim performed according to a conditioned determined by one or more sensors.