WO2018084701A1 - System for filtering a liquid, method for operating such a system and roll replacement method - Google Patents

System for filtering a liquid, method for operating such a system and roll replacement method Download PDF

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Publication number
WO2018084701A1
WO2018084701A1 PCT/NL2017/050703 NL2017050703W WO2018084701A1 WO 2018084701 A1 WO2018084701 A1 WO 2018084701A1 NL 2017050703 W NL2017050703 W NL 2017050703W WO 2018084701 A1 WO2018084701 A1 WO 2018084701A1
Authority
WO
WIPO (PCT)
Prior art keywords
filter medium
roll
receptacle
guide
side wall
Prior art date
Application number
PCT/NL2017/050703
Other languages
French (fr)
Inventor
Roger Johannes Alexander WENSINK
Original Assignee
R & R Holding B.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by R & R Holding B.V. filed Critical R & R Holding B.V.
Publication of WO2018084701A1 publication Critical patent/WO2018084701A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/09—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with filtering bands, e.g. movable between filtering operations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/09—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with filtering bands, e.g. movable between filtering operations
    • B01D29/096—Construction of filtering bands or supporting belts, e.g. devices for centering, mounting or sealing the filtering bands or the supporting belts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/04—Filters with filtering elements which move during the filtering operation with filtering bands or the like supported on cylinders which are impervious for filtering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/056—Construction of filtering bands or supporting belts, e.g. devices for centering, mounting or sealing the filtering bands or the supporting belts

Definitions

  • the invention relates to a system for filtering a liquid.
  • the liquid which can be any kind of liquid, may contain contaminants that need to be filtered out, so that for instance the liquid can be re-used or can environmentally be disposed of.
  • a known filtering system makes use of a flexible filter medium, e.g. a cloth-like filter medium, provided on a roll. The filter medium is drawn from the roll into a receptacle, whereafter the liquid is provided on the filter medium. While passing the filter medium, contaminants in the liquid remain in or on the filter medium depending on the size of the pores in the filter medium.
  • the filter medium Over time the filter medium will become clogged due to the build up of contaminants.
  • the clogging can be easily dealt with by moving the filter medium through the receptacle so that a new fresh part of the filter medium takes over the filtering.
  • the dirty filter medium can e.g. be deposited in a bin.
  • An advantage of the flexible filter medium is that no backwash of the filter medium is required.
  • the filter medium including contaminants is easily removed from the system and replaced by new filter medium.
  • a system for filtering a liquid comprising: a support for a roll with filter medium;
  • a substantially rectangular receptacle having a bottom with one or more through- holes for the passage of filtered liquid and four side walls which in use extend obliquely upwards and away from the bottom, said four side walls including a filter medium entering side wall, a filter medium leaving side wall opposite the filter medium entering side wall, and two guiding side walls extending on opposite sides of the bottom between the filter medium entering side wall and the filter medium leaving side wall;
  • a filter medium drawing device arranged at or near the filter medium leaving side wall of the receptacle to draw filter medium through the receptacle;
  • the support is able to support a roll with filter medium having a width that is larger than a width of the bottom
  • the support is arranged at or near the filter medium entering side wall of the receptacle
  • first and second guide are moveable between an operational position, in which they are able to guide filter medium in close proximity over the bottom and the guiding side walls, and a non-operational position at a distance from the receptacle, in which filter medium can be introduced through the receptacle to the filter medium drawing device without interference from the first and second guide,
  • first and second guide are configured to keep the filter medium in close proximity of the bottom and the guiding side walls when the filter medium drawing device draws filter medium through the receptacle.
  • the receptacle being substantially rectangular also includes a square shaped receptacle and shapes that closely resemble a rectangular shape.
  • the corners of the receptacle may be rounded, and the four side walls do not necessarily have to be straight, but may be curved.
  • a side wall may have a radius of curvature which is larger than a length of the corresponding side wall.
  • the system is configured such that in use the filter medium is drawn from the roll by the filter medium drawing device in a transport direction from the filter medium entering side wall to the filter medium leaving side wall, which transport direction is substantially parallel to the guiding side walls.
  • the width of the filter medium and the width of the bottom of the receptacle are dimensions in a transverse direction perpendicular to the transport direction. Using these directions, it is possible that a length of the bottom, which length is the dimension of the bottom in the transport direction, is smaller than the width of the bottom.
  • the feature that the support is arranged at or near the filter medium entering side wall is another way of saying that the support is arranged on the filter medium entering side wall side of the receptacle in order to allow filter medium from the roll to be supplied to the filter medium entering side wall.
  • the filter medium drawing device is arranged at or near the filter medium leaving side wall of the receptacle.
  • the filter medium drawing device is arranged on the filter medium leaving side wall side of the receptacle in order to allow the filter medium drawing device to draw filter medium through the receptacle.
  • the phrase "in close proximity" includes the possibility that the filter medium at least partially, possibly entirely engages with the bottom and/or guiding side walls, but also includes the possibility that the filter medium follows the contour of the bottom and guiding side walls at a relatively small distance from the bottom and guiding side walls, which relatively small distance is preferably at most 2cm, more preferably at most 1cm, and most preferably at most 5mm.
  • the receptacle having a bottom and four side walls extending, in use, obliquely upwards and away from the bottom allows the receptacle to hold a predetermined amount of liquid before overflowing in case the filter medium gets clogged.
  • An advantage of the filter medium drawing device being arranged at or near the filter medium leaving side is that no complex conveyor belt is required.
  • the filter medium only needs to be provided from the roll with filter medium to the filter medium drawing device to allow the filter medium drawing device to move the filter medium through the receptacle.
  • the first and second guide are provided to ensure that the filter medium follows the contour of the bottom and guiding side walls and to substantially counteract filter medium movement in a direction perpendicular to the bottom and guiding side walls that may be caused by the filter medium drawing device when drawing the filter medium through the receptacle.
  • An advantage of the configuration of the first and second guide is that they can be moved away to allow a new roll with filter medium be placed on the support and to allow the introduction of filter medium in the receptacle to the filter medium drawing device.
  • An advantage of the support being able to support a roll with filter medium having a width that is larger than a width of the bottom of the receptacle is that the filter medium can be drawn through the receptacle such that the filter medium also follows the contour of the guiding side walls.
  • the filter medium forms a collecting volume allowing the receptacle to hold a certain volume of liquid such that the liquid level is below an edge of the filter medium on the guiding side walls, thereby ensuring that no liquid can undesirably get around the filter medium without being filtered.
  • the filter medium drawing device is operated manually by an operator to regularly, i.e. with a substantially constant time interval between operating the filter medium drawing device, or based on a liquid level in the receptacle, move the filter medium through the receptacle so that filtering is performed using a new fresh piece of filter medium.
  • Such a system can be referred to as being manually controlled.
  • the system comprises a control unit to control the filter medium drawing device.
  • the control unit may comprise a timer to regularly move the filter medium thereby preventing that the level of liquid in the receptacle gets above a desired level to ensure that liquid is able to get around the filter medium without being filtered.
  • This has the advantage that no level sensor is required.
  • the timer of the control unit can easily be set when the liquid to be filtered is relatively constant in terms of pollution/contamination and amount and thus the clogging of the filter medium can be predicted with a significant degree of certainty.
  • Such a system can be referred to as being passively controlled.
  • the system comprises a level sensor to measure a liquid level in the receptacle.
  • the liquid level in the receptacle can be used as an indication of the amount of clogging of the filter medium in the receptacle.
  • the level sensor can be used in a manually controlled systems by indicating the liquid level to an operator or by providing a warning signal when the liquid level reaches a predetermined value.
  • An advantage of the level sensor is that this indication or warning signal can be easily provided remote from the system, so that the operator does not have to be near the system to receive the indication or warning signal.
  • the level sensor can also be used in a so-called actively controlled system.
  • the system then comprises a control unit configured to receive an output signal of the level sensor and to control the filter medium drawing device based on the output signal of the level sensor.
  • the control unit may for instance be configured to move the filter medium when the liquid level in the receptacle reaches or increases to above a first value and to stop moving the filter medium when the liquid level reaches or decreases to below a second value, where the second value is less or equal to the first value.
  • the level sensor may alternatively or additionally be used for overflow protection purposes.
  • the liquid level may rise to a level such that the receptacle starts to overflow.
  • the level sensor can be used to detect this abnormal liquid level and may indicate this or provide a warning signal to an operator. The operator is then able to stop or at least lower the supply of liquid to the receptacle in order to prevent further overflow and damage, and to determine and remove the cause of the overflow. This can also be done actively.
  • the level sensor may output a signal to a control unit, which control unit is able to determine whether an overflow is imminent or occurring based on the signal and to stop or at least decrease the supply of liquid to the receptacle, for instance by stopping the operation of a pump or by closing a valve.
  • the level sensor is a float switch providing two discrete signals, one signal indicating that the liquid level is below a predetermined value, and a second signal indicating that the liquid level is above a predetermined value. The presence of the second signal or the absence of the first signal can then be used to operate the filter medium drawing device or as a warning signal.
  • the system comprises a sensor configured to detect an amount of filter medium still present on the roll. This can be done in various ways, including but not limited to:
  • the output signal of the sensor can be used to determine how much filter medium is still present on the roll;
  • the diameter of the roll is a measure for the amount of filter medium still present on the roll;
  • a marker may be introduced at a location where the detected presence of the marker indicates that a predetermined amount of filter medium is still present on the roll;
  • the filter medium drawing device uses the filter medium drawing device to determine the length of filter medium that has passed the filter medium drawing device, e.g. by counting the number of revolutions of a driving shaft.
  • the output of the sensor can be used as an indication that a 'new' roll with filter medium is needed.
  • a warning can thus be given to an operator, but alternatively or additionally, the signal can be used to automatically stop the supply of liquid to the receptacle, so that the liquid level in the receptacle reduces to zero, i.e. the receptacle is emptied, thereby allowing the Old' filter medium and/or 'old' roll to be removed and to replace the Old' roll by a 'new' roll with filter medium and to subsequently introduce the 'new' filter medium in the receptacle and to the filter medium drawing device after which filtering can be resumed.
  • the first and/or second guide can be locked in the operational position to keep the filter medium in close proximity of the bottom and the guiding side walls.
  • the first and/or second guide then first needs to be unlocked to allow them to be moved towards the non-operational position.
  • the first and/or second guide are biased towards the operational position, wherein the biasing force is sufficient to keep the filter medium in close proximity of the bottom and the guiding side walls when the filter medium drawing device draws filter medium through the receptacle, but low enough to allow the first and/or second guide to be moved against the biasing force towards the non-operational position.
  • the first and/or second guide are temporarily lockable in the non- operational position to keep the first and/or second guide in the non-operational position. This has the advantage that when moving the first and/or second guide towards the non- operational position is done manually, the operator can lock the first and/or second guide into the non-operational position to have his hands free to carry out other steps or actions without the first and/or second guide automatically moving back to the operational position in which the first and/or second guide could interfere with the other steps or actions.
  • the first guide comprises a plate arranged parallel to the filter medium entering side wall in the operational position, which plate has a similar shape and dimensions seen in the width direction as the portion of the filter medium entering side wall it faces to force the filter medium towards the bottom and the guiding side walls in the operational position.
  • the plate of the first guide comprises an extension at the bottom side of the plate which extends parallel to the bottom of the receptacle in the operational position. This aids in guiding the filter medium over the bottom of the receptacle.
  • the plate of the first guide comprises extensions at the guiding side walls sides of the plate which extend parallel to the corresponding guiding side walls. This aids in guiding the filter medium over the guiding side walls.
  • the second guide comprises a plate arranged parallel to the filter medium leaving side wall in the operational position, which plate has a similar shape and dimensions seen in the width direction as the portion of the filter medium leaving side wall it faces to force the filter medium towards the bottom and the guiding side walls in the operational position.
  • the plate of the second guide comprises an extension at the bottom side of the plate which extends away from the bottom of the receptacle in the operational position.
  • the plate of the second guide comprises extensions at the guiding side walls sides of the plate which extend away from the corresponding guiding side walls.
  • the first and/or second guide comprise guiding rolls provided respectively at the transition from filter medium entering side wall to bottom and the transition from bottom to filter medium leaving side wall to force the filter medium towards the bottom in the operational position.
  • the first and/or second guide comprise guiding rolls provided respectively at the transition from filter medium entering side wall to guiding side wall and the transition from guiding side wall to filter medium leaving side wall to force the filter medium towards the guiding side walls in the operational position.
  • the first and/or second guide are pivotable about a respective pivot axis for movement between the operational and the non-operational position.
  • the pivot axis of the first guide coincides with a rotation axis provided by the support for the roll with filter medium.
  • the system comprises a bin for disposal of the filter medium after being used for filtering the liquid.
  • the system may further comprise a cutter, e.g. between the filter medium drawing device and the bin, so that the filter medium in the bin can be separated by the cutter from the filter medium still in the receptacle, e.g. for emptying the bin.
  • the filter medium drawing device comprises a second support for supporting a second roll, wherein the filter medium drawing device draws the filter medium through the receptacle by winding the filter medium on the second roll on the second support thereby unwinding the filter medium from the roll on the other support, which roll and support may then also be referred to as first roll and first support to distinguish them from the second roll and second support.
  • the filter medium drawing device comprises two drive rolls in opposite arrangement, wherein the filter medium is to be clamped in between the two drive rolls in order to be moved due to friction with the drive rolls, and wherein at least one roll is rotationally driveable by a respective actuator or motor, preferably an electric actuator or electric motor.
  • At least one of the two drive rolls is provided with teeth for better grip between the drive rolls and the filter medium.
  • one of the two drive rolls is removable to allow filter medium to be positioned on the other one of the two drive rolls after which the removed drive roll is returned into its original position to provide the filter medium in between the two drive rolls. Removing in this context means moving the drive roll such that sufficient space is provided between the two drive rolls for introducing the filter medium on the other drive roll.
  • the second guide and the removable drive roll are coupled such that moving the second guide from the operational position to the non-operational position also moves the removable drive roll away from the other drive roll.
  • the pivot axis of the second guide coincides with a rotation axis of one of the two drive rolls of the filter medium drawing device.
  • the system includes the roll with filter medium supported by the support, wherein the width of the filter medium is larger than the width of the bottom.
  • the roll with filter medium is supported on the support such that a center line of the filter medium on the roll is aligned with a center of the bottom.
  • the filter medium will extend substantially as much on one of the guiding side walls as on the other one of the guiding side walls.
  • the system comprises a supply conduit or at least a support for such supply conduit to supply liquid to the receptacle.
  • the invention further relates to a method for operating the system according to the invention, said method comprising the following steps:
  • driving the filter medium drawing device is carried out until the liquid level is below the predetermined level.
  • the invention also relates to a method for replacing an empty or nearly empty roll by a new roll filled with filter medium in a system according to the invention, said method comprising the following steps:
  • the filter medium drawing device comprises two drive rolls in opposite arrangement, wherein the filter medium is to be clamped in between the two drive rolls in order to be moved due to friction with the drive rolls, and wherein at least one roll is rotationally driveable by a respective actuator or motor, wherein one of the two drive rolls is removable to allow filter medium to be positioned on the other one of the two drive rolls after which the removed drive roll is returned into its original position to provide the filter medium in between the two drive rolls, and wherein the sub-steps include the steps of removing the removeable drive roll, position the filter medium on the other drive roll, and returning the removed drive roll back to its original position.
  • FIG. 1 depicts a perspective view of a system for filtering a liquid according to an embodiment of the invention in an operational configuration
  • FIG. 2 depicts a top view of the system of Fig. 1 ;
  • Fig. 3 depicts a cross sectional view of the system of Fig. 1 along line A-A;
  • Fig. 4 depicts a side view of the system of Fig. 1 ;
  • Fig. 5 depicts a front view of the system of Fig. 1 ;
  • Fig. 6 depicts a perspective view of the system of Fig. 1 in a non-operational configuration
  • Fig. 7 depicts a top view of the system of Fig. 1 in the non-operational
  • Fig. 8 depicts a side view of the system of Fig. 1 in the non-operational
  • Fig. 9 depicts a top view of a system for filtering a liquid according to another embodiment of the invention.
  • Fig. 10 depicts a side view of the system of Fig. 9.
  • Figs. 1-8 depict a system for filtering a liquid according to an embodiment of the invention
  • the system has at least two different configurations, namely an operational configuration as shown in the Figs. 1-5, and a non-operational configuration as shown in the Figs. 6-8.
  • the operational and non-operational configurations will be elucidated in more detail below.
  • the liquid can be any type of liquid, including but not limited to waste water, contaminated water, contaminated oil, etc.
  • the system may in particular be suitable to be used in combination with a filtration unit that uses backwashing to carry out preventive maintenance in order to reuse the filter media.
  • the dirty backwash water can then be filtered by the system according to the invention so that the backwash water can be reused or can be thrown away without the risk of contaminating the environment.
  • the system comprises a rectangular receptacle 1 having a bottom 3 with a plurality of through-holes 4 to allow the passage of filtered liquid.
  • the through-holes 4 may also be called openings.
  • the through-holes 4 allow filtered liquid to flow from the receptacle into a reservoir or other kind of container/holder (not shown).
  • the through-holes do not have any functionality with regard to filtering the liquid, therefore the size of the through-holes is not critical.
  • the total cross-sectional area of the through-holes only needs to be sufficiently large to allow liquid to quickly leave the receptacle once it has passed a filter medium in the receptacle.
  • the bottom is provided with a plurality of through-holes, but an embodiment with only one through-hole also falls within the scope of the current invention.
  • an advantage of the plurality of through-holes in the shown embodiment is that the bottom is still able to support the filter medium when necessary, e.g. when the liquid level in the receptacle increases and the liquid above the filter medium applies a load to the filter medium.
  • other measures, such as tensioning the filter medium, to counteract the load are not required per se.
  • the through-holes are made such that all edges are rounded to prevent any cutting or tearing action on the filter medium moving over the through-holes.
  • the four side walls can best be seen in Fig. 7.
  • the four side walls are straight and make an angle of about 45 degrees with the horizontal.
  • the four sides do not necessarily have to be straight, may also be curved, e.g. in the form of a circle segment in cross section or oval portion. This may provide a smooth transition from the bottom to the four side walls. This smooth transition may also be provided by a rounded edge.
  • the support 8 and roll 9 are visible in all figures where possible.
  • the filter medium 10 has been omitted in some figures for clarity reasons and is only shown in Figs.
  • the support 8 supports the roll 9 at both ends of the roll 9.
  • the support 8 comprises an opening for each end of the roll 9, which openings are open at the upper end to receive a respective shaft portion 11 a, 11 b of a shaft 1 1 of the roll 9 and to define a rotation axis RA1 for the roll 9.
  • the filter medium drawing device 20 comprises in this embodiment a first drive roll 21 with a rotation axis RA2 and a second drive roll 22 with a rotation axis RA3 in opposite arrangement with respect to each other.
  • the distance between the first and second drive roll 21 , 22 is small enough to clamp the filter medium 10 in between the two drive rolls 21 , 22 to be moveable due to friction with the drive rolls 21 , 22.
  • the second drive roll 22 is provided with rings of teeth 23 that are pressed into the filter medium for grip.
  • the first drive roll 21 may alternatively or additionally comprise teeth for improved grip on the filter medium.
  • the teeth of the first drive roll may mate with the teeth of the second drive roll, e.g. like gears.
  • the first drive roll 21 comprises a rotational drive, actuator or motor for rotating the first drive roll 21 and thus to draw the filter medium 10 through the receptacle 1.
  • the second drive roll 22 will also rotate due to the friction between the moving filter medium and the second drive roll 22.
  • Both the support 8 and the filter medium drawing device 20 are arranged above the receptacle substantially in line with the respective filter medium entering side wall 5 and filter medium leaving side wall 6, so that filter medium is smoothly supplied from the roll 9 to the filter medium entering side wall 5 and smoothly provided from the filter medium leaving side wall 6 to the filter medium drawing device 20.
  • the filter medium will extend above the receptacle 1 between the roll 9 and the filter medium drawing device 20. This will not result in an effective filtering action and also includes a high risk of liquid not being received in the receptacle or liquid entering the receptacle without having passed the filter medium.
  • the system comprises a first guide 30 arranged at the filter medium entering side wall 5 and a second guide 40 arranged at the filter medium leaving side wall 6.
  • the first and second guide 30, 40 are moveable between an operational position as shown in Figs. 1-5, in which they are able to guide filter medium 10 in close proximity over the bottom 3 and the guiding side walls 7a, 7b, and a non-operational position as shown in Figs. 6-8, in which they are at a distance from the receptacle 1.
  • the first guide 30 can even be removed entirely.
  • the first guide 30 is pivotably attached to the shaft 11 of the roll 9, so that when replacing the roll 9, the first guide has to be attached to the new roll 9.
  • the second guide 40 is pivotably attached to a shaft of the second drive roll 22.
  • Filter medium 10 from the new roll 9 can then be introduced into the receptacle and to the filter medium drawing device 20 without interference from the first and second guide when they are in the non-operational position.
  • the first and second guide 30, 40 are so close to the respective filter medium entering side wall 5 and filter medium leaving side wall 6, that it is not easy to introduce new filter medium between the guides and respective side walls.
  • the first drive roll 21 may be removable or moveable to provide sufficient space between the first drive roll and the second drive roll to introduce filter medium in between the two drive rolls.
  • the first guide 30 and the second guide 40 can be locked in the operational position.
  • the support 8 comprises a hole 31 and the first guide comprises a pin 32 at each side of the first guide that can be received in the respective hole 31 in the operational position to lock pivotal movement of the first guide about the rotation axis RA1.
  • a support for the second roll 22 comprises a hole 41 and the second guide comprises a pin 42 at each side of the second guide that can be received in the respective hole 41 in the operational position to lock pivotal movement of the second guide about the rotation axis RA3.
  • the first guide 30 comprises a plate 33 arranged substantially parallel to the filter medium entering side wall 5 in the operational position as can be best seen in Fig. 3.
  • the plate 33 has a similar shape and dimensions seen in the width direction as the portion of the filter medium entering side wall 5 it faces as can be best seen in Fig. 2 where the plate 33 blocks the view towards the filter medium entering side wall 5 almost completely.
  • the plate 33 of the first guide 30 further comprises an extension 34 at the bottom side of the plate 33 and extensions 35 at the guiding side walls sides of the plate, which extensions 34, 35 extend parallel to the respective bottom 3 and guiding side walls. This aids in guiding the filter medium along the bottom and guiding side walls of the receptacle.
  • the plate 43 of the first guide 40 further comprises an extension 44 at the bottom side of the plate 43 and extensions 45 at the guiding side walls sides of the plate, which extensions 44, 45 extend away from the respective bottom 3 and guiding side walls. In this way the filter medium cannot catch on the extensions 44, 45 or the plate 43.
  • the system shown in the figures is an actively controlled system including a level sensor 50, a sensor 60 and a control unit CU.
  • the sensor 60 is only schematically depicted in Fig. 3.
  • the control unit CU is only schematically depicted in Figs. 1 and 3.
  • the level sensor 50 is configured to provide a low signal when the liquid level in the receptacle is below a predetermined level and to provide a high signal when the liquid level in the receptacle is above the predetermined level.
  • An output of the level sensor carrying the low or high signal is connected to the control unit CU.
  • the control unit CU is configured to drive the first drive roll 21 upon receiving the high signal from the level sensor to draw fresh new filter medium into the receptacle as a result of which the flow through the filter medium will increase and the liquid level will drop.
  • the level sensor will output the low signal to the control unit and driving of the first drive roll 21 is stopped until the filter medium gets clogged again and the liquid level rises above the predetermined level again.
  • the sensor 60 is a sensor configured to detect when the roll 9 is nearly empty and needs to be replaced. In this embodiment, the sensor 60 detects this by monitoring the diameter of the roll 90 including filter medium. As the filter medium is drawn from the roll 9, the diameter will decrease. Upon reaching a predetermined value, the control unit connected to the sensor 60 is able to indicate that the roll needs to be replaced and may stop the supply of liquid to the receptacle to allow an operator to remove the old roll and filter medium and install a new roll with filter medium.
  • the sensor 60 may also be of the type that a low (or high) signal is outputted when the diameter of the roll is above a predetermined value and a high (or low) signal is outputted when the diameter of the roll is below the predetermined value.
  • the system may further comprise a bin 70 as shown in Fig. 4 to receive filter medium 10 from the filter medium drawing device allowing to dispose of the dirty filter medium 10.
  • Figs. 9 and 10 depict a system for filtering a liquid according to another embodiment of the invention.
  • Fig. 9 depicts a top view while Fig. 10 depicts a side view of the system.
  • the system according to the embodiment of Figs. 9 and 10 is similar in function as the embodiment of Figs. 1-8 with differences that will be highlighted below. To avoid the unduly repetition of features, the features that have already been described in relation to the embodiment of Figs. 1-8 and are similar or even identical will only be described briefly.
  • the system comprises a rectangular receptacle 1 having a bottom 3 with a plurality of through-holes 4 to allow the passage of filtered liquid.
  • the bottom 3 of this embodiment is embodied like a grid or grate in which the combined areas of the through-holes 4 is more than half of the total area of the bottom 3.
  • the width of the elements forming the grid lines is smaller than the width of the through-holes 4. and/or the length of the through-holes 4.
  • through-holes 4 have been depicted in the shown embodiments in a certain pattern and size, it is envisaged that other patterns and sizes are also possible.
  • the pattern and sizes of the through holes 4 are such that the bottom is able to let filtered liquid pass as quickly as possible.
  • the through-holes occupy at least 50% of the bottom area, preferably at least 70% of the bottom area, more preferably at least 80% of the bottom area and most preferably at least 90% of the bottom area.
  • the filter medium 10 is only depicted in Fig. 10.
  • the support 8 supports the roll 9 at both ends of the roll 9.
  • the support 8 comprises an opening for each end of the roll 9, which openings are open at the upper end to receive a respective shaft portion of a shaft 1 1 of the roll 9 and to define a rotation axis RA1 for the roll 9.
  • the filter medium drawing device 20 comprises in this embodiment a first drive roll 21 with a rotation axis RA2 and a second drive roll 22 with a rotation axis RA3 in opposite arrangement with respect to each other.
  • the distance between the first and second drive roll 21 , 22 is small enough to clamp the filter medium 10 in between the two drive rolls 21 , 22 to be moveable due to friction with the drive rolls 21 , 22.
  • the first and second drive rolls 21 ,22 is provided with rings of teeth that are pressed into the filter medium for grip.
  • the filter medium drawing device 20 is in this embodiment covered by a cover 210 to prevent undesired access to the filter medium drawing device 20 thereby reducing the risk of accidents with the filter medium drawing device.
  • the cover 210 may be removable for maintenance or repair purposes and/or for inserting or removing filter medium.
  • the cover 210 is partially transparent to show the filter medium drawing device 20.
  • the system comprises a first guide 30 arranged at the filter medium entering side wall 5 and a second guide 40 arranged at the filter medium leaving side wall 6.
  • first and second guide are similar to the first and second guide of the embodiment of Figs. 1-8.
  • the first and second guide 30, 40 are shown in the operational position.
  • a plurality of supports 200 e.g. two sets of supports 200 are provided to allow two or more supply systems of liquid to be filtered to be connected to the filtering system. This is shown in the
  • each supply system in this embodiment comprises a tube 220 received in and supported by a set of supports 200, wherein substantially half way, the tube comprises an exit opening 230 to allow liquid to be filtered to leave the tube and access the receptacle.
  • This is shown in Fig. 10 for the left most tube 220 by omitting a portion of the guiding side wall 7b.
  • the exit opening 230 is provided at a distance below the tube 220 to be as close to the bottom 3 of the receptacle 1 as possible.
  • Fig. 9 Shown in Fig. 9 are two level sensors 240a, 240b configured to measure a liquid level in the receptacle.
  • One level sensor e.g. level sensor 240a
  • the other level sensor e.g. level sensor 240b
  • the level sensors 240a, 240b may for instance be a float switch each switching at different levels of liquid in the receptacle, e.g. one level indicating that filter medium is clogged and needs to be replaced and another, higher, level indicating that the receptacle is overflowing or that there is a high risk that an overflow will occur if no countermeasures are taken.
  • a sensor 250 configured to detect an amount of filter medium still present on the roll 9.
  • the sensor 250 may be configured to engage with an outer surface of the filter medium on the roll and be embodied as a switch in which a discrete signal is outputted by the sensor 250 to indicate that the diameter of the filter medium roll is larger than a predetermined value and thus there is still sufficient filter medium present to continue operation of the system, and in which another discrete signal is outputted by the sensor 250 when the diameter of the filter medium roll is below a predetermined value and thus the filter medium roll needs to be replaced any time soon.

Abstract

This invention relates to a system for filtering liquid in which a filter medium is positioned in a receptacle and drawn through the receptacle upon clogging of the filter medium so that the clogged filter medium is replaced by a fresh portion of filter medium. In order to keep the filter medium close to the receptacle, a first and second guide are provided, which first and second guide can be moved to a non-operational position to allow an empty roll with filter medium to be replaced by a new roll filled with filter medium.

Description

TITLE OF THE INVENTION
System for filtering a liquid, method for operating such a system and roll replacement method BACKGROUND OF THE INVENTION
The invention relates to a system for filtering a liquid. The liquid, which can be any kind of liquid, may contain contaminants that need to be filtered out, so that for instance the liquid can be re-used or can environmentally be disposed of. A known filtering system makes use of a flexible filter medium, e.g. a cloth-like filter medium, provided on a roll. The filter medium is drawn from the roll into a receptacle, whereafter the liquid is provided on the filter medium. While passing the filter medium, contaminants in the liquid remain in or on the filter medium depending on the size of the pores in the filter medium.
Over time the filter medium will become clogged due to the build up of contaminants. The clogging can be easily dealt with by moving the filter medium through the receptacle so that a new fresh part of the filter medium takes over the filtering. The dirty filter medium can e.g. be deposited in a bin. An advantage of the flexible filter medium is that no backwash of the filter medium is required. The filter medium including contaminants is easily removed from the system and replaced by new filter medium.
A prior art example of such a filtering system is disclosed in US3,757,949A. A drawback of such a system is that an endless conveyor belt is provided in the receptacle to draw the filter medium through the receptacle. Not only does this result in a complex system, the conveyor belt itself should be permeable for the liquid and also be suitable for the liquid to be filtered as it is immersed in the liquid.
Another drawback associated with this type of filtering systems is that the procedure of installing a roll with filter medium to replace an empty or nearly empty roll may be complex and/or time consuming.
BRIEF SUMMARY OF THE INVENTION
It is an object of the invention to provide a simpler system for filtering a liquid which allows for an easy introduction of the filter medium.
This object is achieved by a system for filtering a liquid, comprising: a support for a roll with filter medium;
a substantially rectangular receptacle having a bottom with one or more through- holes for the passage of filtered liquid and four side walls which in use extend obliquely upwards and away from the bottom, said four side walls including a filter medium entering side wall, a filter medium leaving side wall opposite the filter medium entering side wall, and two guiding side walls extending on opposite sides of the bottom between the filter medium entering side wall and the filter medium leaving side wall;
a filter medium drawing device arranged at or near the filter medium leaving side wall of the receptacle to draw filter medium through the receptacle;
a first guide arranged at the filter medium entering side wall; and
a second guide arranged at the filter medium leaving side wall,
wherein the support is able to support a roll with filter medium having a width that is larger than a width of the bottom,
wherein the support is arranged at or near the filter medium entering side wall of the receptacle,
wherein the first and second guide are moveable between an operational position, in which they are able to guide filter medium in close proximity over the bottom and the guiding side walls, and a non-operational position at a distance from the receptacle, in which filter medium can be introduced through the receptacle to the filter medium drawing device without interference from the first and second guide,
and wherein the first and second guide are configured to keep the filter medium in close proximity of the bottom and the guiding side walls when the filter medium drawing device draws filter medium through the receptacle.
It is noted that the receptacle being substantially rectangular also includes a square shaped receptacle and shapes that closely resemble a rectangular shape. Hence, for instance, the corners of the receptacle may be rounded, and the four side walls do not necessarily have to be straight, but may be curved. For instance, a side wall may have a radius of curvature which is larger than a length of the corresponding side wall.
The system is configured such that in use the filter medium is drawn from the roll by the filter medium drawing device in a transport direction from the filter medium entering side wall to the filter medium leaving side wall, which transport direction is substantially parallel to the guiding side walls. The width of the filter medium and the width of the bottom of the receptacle are dimensions in a transverse direction perpendicular to the transport direction. Using these directions, it is possible that a length of the bottom, which length is the dimension of the bottom in the transport direction, is smaller than the width of the bottom.
The feature that the support is arranged at or near the filter medium entering side wall is another way of saying that the support is arranged on the filter medium entering side wall side of the receptacle in order to allow filter medium from the roll to be supplied to the filter medium entering side wall.
The same applies to the feature that the filter medium drawing device is arranged at or near the filter medium leaving side wall of the receptacle. This is another way of saying that the filter medium drawing device is arranged on the filter medium leaving side wall side of the receptacle in order to allow the filter medium drawing device to draw filter medium through the receptacle. The phrase "in close proximity" includes the possibility that the filter medium at least partially, possibly entirely engages with the bottom and/or guiding side walls, but also includes the possibility that the filter medium follows the contour of the bottom and guiding side walls at a relatively small distance from the bottom and guiding side walls, which relatively small distance is preferably at most 2cm, more preferably at most 1cm, and most preferably at most 5mm.
The receptacle having a bottom and four side walls extending, in use, obliquely upwards and away from the bottom allows the receptacle to hold a predetermined amount of liquid before overflowing in case the filter medium gets clogged.
An advantage of the filter medium drawing device being arranged at or near the filter medium leaving side is that no complex conveyor belt is required. The filter medium only needs to be provided from the roll with filter medium to the filter medium drawing device to allow the filter medium drawing device to move the filter medium through the receptacle.
The first and second guide are provided to ensure that the filter medium follows the contour of the bottom and guiding side walls and to substantially counteract filter medium movement in a direction perpendicular to the bottom and guiding side walls that may be caused by the filter medium drawing device when drawing the filter medium through the receptacle. An advantage of the configuration of the first and second guide is that they can be moved away to allow a new roll with filter medium be placed on the support and to allow the introduction of filter medium in the receptacle to the filter medium drawing device. An advantage of the support being able to support a roll with filter medium having a width that is larger than a width of the bottom of the receptacle is that the filter medium can be drawn through the receptacle such that the filter medium also follows the contour of the guiding side walls. As a result thereof, the filter medium forms a collecting volume allowing the receptacle to hold a certain volume of liquid such that the liquid level is below an edge of the filter medium on the guiding side walls, thereby ensuring that no liquid can undesirably get around the filter medium without being filtered.
In its most simple configuration, the filter medium drawing device is operated manually by an operator to regularly, i.e. with a substantially constant time interval between operating the filter medium drawing device, or based on a liquid level in the receptacle, move the filter medium through the receptacle so that filtering is performed using a new fresh piece of filter medium. Such a system can be referred to as being manually controlled.
In an embodiment, the system comprises a control unit to control the filter medium drawing device. The control unit may comprise a timer to regularly move the filter medium thereby preventing that the level of liquid in the receptacle gets above a desired level to ensure that liquid is able to get around the filter medium without being filtered. This has the advantage that no level sensor is required. The timer of the control unit can easily be set when the liquid to be filtered is relatively constant in terms of pollution/contamination and amount and thus the clogging of the filter medium can be predicted with a significant degree of certainty. Such a system can be referred to as being passively controlled.
In an embodiment, the system comprises a level sensor to measure a liquid level in the receptacle. The liquid level in the receptacle can be used as an indication of the amount of clogging of the filter medium in the receptacle. The level sensor can be used in a manually controlled systems by indicating the liquid level to an operator or by providing a warning signal when the liquid level reaches a predetermined value. An advantage of the level sensor is that this indication or warning signal can be easily provided remote from the system, so that the operator does not have to be near the system to receive the indication or warning signal. The level sensor can also be used in a so-called actively controlled system. The system then comprises a control unit configured to receive an output signal of the level sensor and to control the filter medium drawing device based on the output signal of the level sensor. The control unit may for instance be configured to move the filter medium when the liquid level in the receptacle reaches or increases to above a first value and to stop moving the filter medium when the liquid level reaches or decreases to below a second value, where the second value is less or equal to the first value.
The level sensor may alternatively or additionally be used for overflow protection purposes. When the filter medium can no longer be sufficiently moved, e.g. due to a malfunction of the filter medium drawing device, the liquid level may rise to a level such that the receptacle starts to overflow. The level sensor can be used to detect this abnormal liquid level and may indicate this or provide a warning signal to an operator. The operator is then able to stop or at least lower the supply of liquid to the receptacle in order to prevent further overflow and damage, and to determine and remove the cause of the overflow. This can also be done actively. The level sensor may output a signal to a control unit, which control unit is able to determine whether an overflow is imminent or occurring based on the signal and to stop or at least decrease the supply of liquid to the receptacle, for instance by stopping the operation of a pump or by closing a valve.
In an embodiment, the level sensor is a float switch providing two discrete signals, one signal indicating that the liquid level is below a predetermined value, and a second signal indicating that the liquid level is above a predetermined value. The presence of the second signal or the absence of the first signal can then be used to operate the filter medium drawing device or as a warning signal.
In an embodiment, the system comprises a sensor configured to detect an amount of filter medium still present on the roll. This can be done in various ways, including but not limited to:
- detecting the length of filter medium that has passed the sensor. When the total length of the filter medium on the roll is know, the output signal of the sensor can be used to determine how much filter medium is still present on the roll;
detecting the diameter of the roll. As the filter medium is unwound from the roll, the diameter of the roll decreases. Hence, the diameter of the roll is a measure for the amount of filter medium still present on the roll;
detecting a marker in or on the filter medium. When fabricating the roll with filter medium, a marker may be introduced at a location where the detected presence of the marker indicates that a predetermined amount of filter medium is still present on the roll; and
using the filter medium drawing device to determine the length of filter medium that has passed the filter medium drawing device, e.g. by counting the number of revolutions of a driving shaft.
The output of the sensor can be used as an indication that a 'new' roll with filter medium is needed. A warning can thus be given to an operator, but alternatively or additionally, the signal can be used to automatically stop the supply of liquid to the receptacle, so that the liquid level in the receptacle reduces to zero, i.e. the receptacle is emptied, thereby allowing the Old' filter medium and/or 'old' roll to be removed and to replace the Old' roll by a 'new' roll with filter medium and to subsequently introduce the 'new' filter medium in the receptacle and to the filter medium drawing device after which filtering can be resumed.
In an embodiment, the first and/or second guide can be locked in the operational position to keep the filter medium in close proximity of the bottom and the guiding side walls. The first and/or second guide then first needs to be unlocked to allow them to be moved towards the non-operational position.
In an embodiment, the first and/or second guide are biased towards the operational position, wherein the biasing force is sufficient to keep the filter medium in close proximity of the bottom and the guiding side walls when the filter medium drawing device draws filter medium through the receptacle, but low enough to allow the first and/or second guide to be moved against the biasing force towards the non-operational position.
In an embodiment, the first and/or second guide are temporarily lockable in the non- operational position to keep the first and/or second guide in the non-operational position. This has the advantage that when moving the first and/or second guide towards the non- operational position is done manually, the operator can lock the first and/or second guide into the non-operational position to have his hands free to carry out other steps or actions without the first and/or second guide automatically moving back to the operational position in which the first and/or second guide could interfere with the other steps or actions. In an embodiment, the first guide comprises a plate arranged parallel to the filter medium entering side wall in the operational position, which plate has a similar shape and dimensions seen in the width direction as the portion of the filter medium entering side wall it faces to force the filter medium towards the bottom and the guiding side walls in the operational position.
In an embodiment, the plate of the first guide comprises an extension at the bottom side of the plate which extends parallel to the bottom of the receptacle in the operational position. This aids in guiding the filter medium over the bottom of the receptacle.
In an embodiment, the plate of the first guide comprises extensions at the guiding side walls sides of the plate which extend parallel to the corresponding guiding side walls. This aids in guiding the filter medium over the guiding side walls.
In an embodiment, the second guide comprises a plate arranged parallel to the filter medium leaving side wall in the operational position, which plate has a similar shape and dimensions seen in the width direction as the portion of the filter medium leaving side wall it faces to force the filter medium towards the bottom and the guiding side walls in the operational position.
In an embodiment, the plate of the second guide comprises an extension at the bottom side of the plate which extends away from the bottom of the receptacle in the operational position. An advantage thereof is that the filter medium when being drawn through the receptacle cannot catch on the extension or plate of the second guide at the bottom.
In an embodiment, the plate of the second guide comprises extensions at the guiding side walls sides of the plate which extend away from the corresponding guiding side walls. An advantage thereof is that the filter medium when being drawn through the receptacle cannot catch on the extension or plate of the second guide at the corresponding guiding side wall.
In an embodiment, the first and/or second guide comprise guiding rolls provided respectively at the transition from filter medium entering side wall to bottom and the transition from bottom to filter medium leaving side wall to force the filter medium towards the bottom in the operational position.
In an embodiment, the first and/or second guide comprise guiding rolls provided respectively at the transition from filter medium entering side wall to guiding side wall and the transition from guiding side wall to filter medium leaving side wall to force the filter medium towards the guiding side walls in the operational position. In an embodiment, the first and/or second guide are pivotable about a respective pivot axis for movement between the operational and the non-operational position. In an embodiment, the pivot axis of the first guide coincides with a rotation axis provided by the support for the roll with filter medium.
In an embodiment, the system comprises a bin for disposal of the filter medium after being used for filtering the liquid. The system may further comprise a cutter, e.g. between the filter medium drawing device and the bin, so that the filter medium in the bin can be separated by the cutter from the filter medium still in the receptacle, e.g. for emptying the bin.
In an embodiment, the filter medium drawing device comprises a second support for supporting a second roll, wherein the filter medium drawing device draws the filter medium through the receptacle by winding the filter medium on the second roll on the second support thereby unwinding the filter medium from the roll on the other support, which roll and support may then also be referred to as first roll and first support to distinguish them from the second roll and second support.
In an embodiment, the filter medium drawing device comprises two drive rolls in opposite arrangement, wherein the filter medium is to be clamped in between the two drive rolls in order to be moved due to friction with the drive rolls, and wherein at least one roll is rotationally driveable by a respective actuator or motor, preferably an electric actuator or electric motor.
In an embodiment, at least one of the two drive rolls is provided with teeth for better grip between the drive rolls and the filter medium. In an embodiment, one of the two drive rolls is removable to allow filter medium to be positioned on the other one of the two drive rolls after which the removed drive roll is returned into its original position to provide the filter medium in between the two drive rolls. Removing in this context means moving the drive roll such that sufficient space is provided between the two drive rolls for introducing the filter medium on the other drive roll. In an embodiment, the second guide and the removable drive roll are coupled such that moving the second guide from the operational position to the non-operational position also moves the removable drive roll away from the other drive roll. In an embodiment, the pivot axis of the second guide coincides with a rotation axis of one of the two drive rolls of the filter medium drawing device.
In an embodiment, the system includes the roll with filter medium supported by the support, wherein the width of the filter medium is larger than the width of the bottom. Preferably, the roll with filter medium is supported on the support such that a center line of the filter medium on the roll is aligned with a center of the bottom. As a result thereof, the filter medium will extend substantially as much on one of the guiding side walls as on the other one of the guiding side walls.
In an embodiment, the system comprises a supply conduit or at least a support for such supply conduit to supply liquid to the receptacle.
The invention further relates to a method for operating the system according to the invention, said method comprising the following steps:
a) providing the system with the first and second guide in the operational position and a roll with filter medium on the support, wherein filter medium extends between the roll and the filter medium drawing device while being in close proximity of the bottom and guiding side walls of the receptacle;
b) supplying liquid to the receptacle to be filtered by the filter medium;
c) monitoring a liquid level in the receptacle;
d) driving the filter medium drawing device when the liquid level is above a
predetermined level to draw the filter medium through the receptacle.
In an embodiment, driving the filter medium drawing device is carried out until the liquid level is below the predetermined level.
It is noted here that features and method steps of operating the system according to the invention described above in relation to the system may also be combined with the method according to the invention to avoid unduly repeating of these features and method steps. The invention also relates to a method for replacing an empty or nearly empty roll by a new roll filled with filter medium in a system according to the invention, said method comprising the following steps:
a) providing the system with the first and second guide in the operational position and a roll with filter medium on the support, wherein filter medium extends between the roll and the filter medium drawing device while being in close proximity of the bottom and guiding side walls of the receptacle;
b) monitoring the amount of filter medium on the roll;
c) when the amount of filter medium on the roll is below a predetermined value, carrying out the following sub-steps:
moving the first and second guide to the non-operational position;
removing the roll and the filter medium;
installing the new roll filled with filter medium;
iv. introducing the filter medium from the new roll in the receptacle and to the filter medium drawing device;
v. moving the first and second guide to the operational position.
In an embodiment, the filter medium drawing device comprises two drive rolls in opposite arrangement, wherein the filter medium is to be clamped in between the two drive rolls in order to be moved due to friction with the drive rolls, and wherein at least one roll is rotationally driveable by a respective actuator or motor, wherein one of the two drive rolls is removable to allow filter medium to be positioned on the other one of the two drive rolls after which the removed drive roll is returned into its original position to provide the filter medium in between the two drive rolls, and wherein the sub-steps include the steps of removing the removeable drive roll, position the filter medium on the other drive roll, and returning the removed drive roll back to its original position.
It is noted here that features and method steps of operating the system according to the invention described above in relation to the system and method may also be combined with the replacing method according to the invention to avoid unduly repeating of these features and method steps.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in a non-limiting way with reference to the
accompanying drawings in which like parts are indicated by like reference symbols and in which: Fig. 1 depicts a perspective view of a system for filtering a liquid according to an embodiment of the invention in an operational configuration; Fig. 2 depicts a top view of the system of Fig. 1 ;
Fig. 3 depicts a cross sectional view of the system of Fig. 1 along line A-A;
Fig. 4 depicts a side view of the system of Fig. 1 ;
Fig. 5 depicts a front view of the system of Fig. 1 ;
Fig. 6 depicts a perspective view of the system of Fig. 1 in a non-operational configuration;
Fig. 7 depicts a top view of the system of Fig. 1 in the non-operational
configuration of Fig. 6;
Fig. 8 depicts a side view of the system of Fig. 1 in the non-operational
configuration of Fig. 6;
Fig. 9 depicts a top view of a system for filtering a liquid according to another embodiment of the invention; and
Fig. 10 depicts a side view of the system of Fig. 9.
DETAILED DESCRIPTION OF THE INVENTION
Figs. 1-8 depict a system for filtering a liquid according to an embodiment of the invention The system has at least two different configurations, namely an operational configuration as shown in the Figs. 1-5, and a non-operational configuration as shown in the Figs. 6-8. The operational and non-operational configurations will be elucidated in more detail below.
In principle, the liquid can be any type of liquid, including but not limited to waste water, contaminated water, contaminated oil, etc. The system may in particular be suitable to be used in combination with a filtration unit that uses backwashing to carry out preventive maintenance in order to reuse the filter media. The dirty backwash water can then be filtered by the system according to the invention so that the backwash water can be reused or can be thrown away without the risk of contaminating the environment.
The system comprises a rectangular receptacle 1 having a bottom 3 with a plurality of through-holes 4 to allow the passage of filtered liquid. In the figures only a few of the through-holes have been designated with reference numeral 4. The through-holes 4 may also be called openings.
The through-holes 4 allow filtered liquid to flow from the receptacle into a reservoir or other kind of container/holder (not shown). The through-holes do not have any functionality with regard to filtering the liquid, therefore the size of the through-holes is not critical. The total cross-sectional area of the through-holes only needs to be sufficiently large to allow liquid to quickly leave the receptacle once it has passed a filter medium in the receptacle.
In this embodiment, the bottom is provided with a plurality of through-holes, but an embodiment with only one through-hole also falls within the scope of the current invention. However, an advantage of the plurality of through-holes in the shown embodiment is that the bottom is still able to support the filter medium when necessary, e.g. when the liquid level in the receptacle increases and the liquid above the filter medium applies a load to the filter medium. When the bottom is able to support the filter medium, other measures, such as tensioning the filter medium, to counteract the load are not required per se.
Preferably, the through-holes are made such that all edges are rounded to prevent any cutting or tearing action on the filter medium moving over the through-holes.
Extending from the bottom 3, in an oblique direction upwards and away from the bottom 3, are four side walls. These four side walls include a filter medium entering side wall 5, a filter medium leaving side wall 6 opposite the filter medium entering side wall 5, and two guiding side walls 7a, 7b extending on opposite sides of the bottom between the filter medium entering side wall and the filter medium leaving side wall.
The four side walls can best be seen in Fig. 7. In this embodiment, the four side walls are straight and make an angle of about 45 degrees with the horizontal. However, any other angle between 10-60 degrees is possible. The four sides do not necessarily have to be straight, may also be curved, e.g. in the form of a circle segment in cross section or oval portion. This may provide a smooth transition from the bottom to the four side walls. This smooth transition may also be provided by a rounded edge. Provided near the filter medium entering side wall 5, and in this case attached to the receptacle 1 itself, is a support 8 for a roll 9 with filter medium 10. The support 8 and roll 9 are visible in all figures where possible. The filter medium 10 has been omitted in some figures for clarity reasons and is only shown in Figs. 3 and 4. The support 8 supports the roll 9 at both ends of the roll 9. In this embodiment, the support 8 comprises an opening for each end of the roll 9, which openings are open at the upper end to receive a respective shaft portion 11 a, 11 b of a shaft 1 1 of the roll 9 and to define a rotation axis RA1 for the roll 9.
In this way, replacing an empty or nearly empty roll 9 with a new roll 9 filled with filter medium 10 is easy as the roll 9 can easily be moved upwards to move the shaft portions 1 1a, 11 b out of the respective openings in the support 8, and the shaft portions 11 a, 11 b of the new roll 9 can be positioned in the openings to place the roll 9.
Provided near the filter medium leaving side wall 6, and in this case attached to the receptacle itself, is a filter medium drawing device 20. The filter medium drawing device 20 comprises in this embodiment a first drive roll 21 with a rotation axis RA2 and a second drive roll 22 with a rotation axis RA3 in opposite arrangement with respect to each other.
As can be best seen in Fig. 3, the distance between the first and second drive roll 21 , 22 is small enough to clamp the filter medium 10 in between the two drive rolls 21 , 22 to be moveable due to friction with the drive rolls 21 , 22. In order to improve the clamping action, the second drive roll 22 is provided with rings of teeth 23 that are pressed into the filter medium for grip. Although not shown, the first drive roll 21 may alternatively or additionally comprise teeth for improved grip on the filter medium. When both drive rolls are provided with teeth, the teeth of the first drive roll may mate with the teeth of the second drive roll, e.g. like gears.
In this embodiment, the first drive roll 21 comprises a rotational drive, actuator or motor for rotating the first drive roll 21 and thus to draw the filter medium 10 through the receptacle 1. The second drive roll 22 will also rotate due to the friction between the moving filter medium and the second drive roll 22. Alternatively or additionally, it is possible that there is a rotational drive, actuator or motor provided for rotating the second drive roll 22.
Both the support 8 and the filter medium drawing device 20 are arranged above the receptacle substantially in line with the respective filter medium entering side wall 5 and filter medium leaving side wall 6, so that filter medium is smoothly supplied from the roll 9 to the filter medium entering side wall 5 and smoothly provided from the filter medium leaving side wall 6 to the filter medium drawing device 20. However, when no further measures are taken, the filter medium will extend above the receptacle 1 between the roll 9 and the filter medium drawing device 20. This will not result in an effective filtering action and also includes a high risk of liquid not being received in the receptacle or liquid entering the receptacle without having passed the filter medium. To keep the filter medium 10 in close proximity of the bottom 3 and the guiding side walls 7a, 7b, also when the filter medium drawing device 20 applies a tensional force to the filter medium to draw the filter medium through the receptacle, the system comprises a first guide 30 arranged at the filter medium entering side wall 5 and a second guide 40 arranged at the filter medium leaving side wall 6.
The first and second guide 30, 40 are moveable between an operational position as shown in Figs. 1-5, in which they are able to guide filter medium 10 in close proximity over the bottom 3 and the guiding side walls 7a, 7b, and a non-operational position as shown in Figs. 6-8, in which they are at a distance from the receptacle 1. The first guide 30 can even be removed entirely. In this embodiment, the first guide 30 is pivotably attached to the shaft 11 of the roll 9, so that when replacing the roll 9, the first guide has to be attached to the new roll 9. The second guide 40 is pivotably attached to a shaft of the second drive roll 22. Filter medium 10 from the new roll 9 can then be introduced into the receptacle and to the filter medium drawing device 20 without interference from the first and second guide when they are in the non-operational position. In the operational position, the first and second guide 30, 40 are so close to the respective filter medium entering side wall 5 and filter medium leaving side wall 6, that it is not easy to introduce new filter medium between the guides and respective side walls.
The first drive roll 21 may be removable or moveable to provide sufficient space between the first drive roll and the second drive roll to introduce filter medium in between the two drive rolls.
In this embodiment, the first guide 30 and the second guide 40 can be locked in the operational position. With respect to the first guide 30, the support 8 comprises a hole 31 and the first guide comprises a pin 32 at each side of the first guide that can be received in the respective hole 31 in the operational position to lock pivotal movement of the first guide about the rotation axis RA1. With respect to the second guide, a support for the second roll 22 comprises a hole 41 and the second guide comprises a pin 42 at each side of the second guide that can be received in the respective hole 41 in the operational position to lock pivotal movement of the second guide about the rotation axis RA3. As a result thereof, tensional loads in the filter medium caused by the filter medium drawing device 20 urging the filter medium upwards will be counteracted by the first and second guide 30, 40 to keep the filter medium in close proximity of the bottom 3 and the guiding side walls 7a, 7b. In this embodiment, the first guide 30 comprises a plate 33 arranged substantially parallel to the filter medium entering side wall 5 in the operational position as can be best seen in Fig. 3. The plate 33 has a similar shape and dimensions seen in the width direction as the portion of the filter medium entering side wall 5 it faces as can be best seen in Fig. 2 where the plate 33 blocks the view towards the filter medium entering side wall 5 almost completely.
The plate 33 of the first guide 30 further comprises an extension 34 at the bottom side of the plate 33 and extensions 35 at the guiding side walls sides of the plate, which extensions 34, 35 extend parallel to the respective bottom 3 and guiding side walls. This aids in guiding the filter medium along the bottom and guiding side walls of the receptacle.
The plate 43 of the first guide 40 further comprises an extension 44 at the bottom side of the plate 43 and extensions 45 at the guiding side walls sides of the plate, which extensions 44, 45 extend away from the respective bottom 3 and guiding side walls. In this way the filter medium cannot catch on the extensions 44, 45 or the plate 43.
The system shown in the figures is an actively controlled system including a level sensor 50, a sensor 60 and a control unit CU. The sensor 60 is only schematically depicted in Fig. 3. The control unit CU is only schematically depicted in Figs. 1 and 3.
The level sensor 50 is configured to provide a low signal when the liquid level in the receptacle is below a predetermined level and to provide a high signal when the liquid level in the receptacle is above the predetermined level. An output of the level sensor carrying the low or high signal is connected to the control unit CU. The control unit CU is configured to drive the first drive roll 21 upon receiving the high signal from the level sensor to draw fresh new filter medium into the receptacle as a result of which the flow through the filter medium will increase and the liquid level will drop. When the liquid level is below the predetermined level, the level sensor will output the low signal to the control unit and driving of the first drive roll 21 is stopped until the filter medium gets clogged again and the liquid level rises above the predetermined level again.
The sensor 60 is a sensor configured to detect when the roll 9 is nearly empty and needs to be replaced. In this embodiment, the sensor 60 detects this by monitoring the diameter of the roll 90 including filter medium. As the filter medium is drawn from the roll 9, the diameter will decrease. Upon reaching a predetermined value, the control unit connected to the sensor 60 is able to indicate that the roll needs to be replaced and may stop the supply of liquid to the receptacle to allow an operator to remove the old roll and filter medium and install a new roll with filter medium. The sensor 60 may also be of the type that a low (or high) signal is outputted when the diameter of the roll is above a predetermined value and a high (or low) signal is outputted when the diameter of the roll is below the predetermined value.
The system may further comprise a bin 70 as shown in Fig. 4 to receive filter medium 10 from the filter medium drawing device allowing to dispose of the dirty filter medium 10.
Figs. 9 and 10 depict a system for filtering a liquid according to another embodiment of the invention. Fig. 9 depicts a top view while Fig. 10 depicts a side view of the system. The system according to the embodiment of Figs. 9 and 10 is similar in function as the embodiment of Figs. 1-8 with differences that will be highlighted below. To avoid the unduly repetition of features, the features that have already been described in relation to the embodiment of Figs. 1-8 and are similar or even identical will only be described briefly.
The system comprises a rectangular receptacle 1 having a bottom 3 with a plurality of through-holes 4 to allow the passage of filtered liquid. Compared to the embodiment of Figs. 1-8, the bottom 3 of this embodiment is embodied like a grid or grate in which the combined areas of the through-holes 4 is more than half of the total area of the bottom 3. In other words, the width of the elements forming the grid lines is smaller than the width of the through-holes 4. and/or the length of the through-holes 4. An advantage thereof is that the total cross-sectional area of the through-holes is sufficiently large to allow liquid to quickly leave the receptacle once it has passed a filter medium in the receptacle.
Although through-holes 4 have been depicted in the shown embodiments in a certain pattern and size, it is envisaged that other patterns and sizes are also possible.
Preferably, the pattern and sizes of the through holes 4 are such that the bottom is able to let filtered liquid pass as quickly as possible. In an embodiment, the through-holes occupy at least 50% of the bottom area, preferably at least 70% of the bottom area, more preferably at least 80% of the bottom area and most preferably at least 90% of the bottom area.
Extending from the bottom 3, in an oblique direction upwards and away from the bottom 3, are four side walls. These four side walls include a filter medium entering side wall 5, a filter medium leaving side wall 6 opposite the filter medium entering side wall 5, and two guiding side walls 7a, 7b extending on opposite sides of the bottom 3 between the filter medium entering side wall 5 and the filter medium leaving side wall 6. Provided near the filter medium entering side wall 5, and in this case attached to the receptacle 1 itself, is a support 8 for a roll 9 with filter medium 10. The filter medium 10 is only depicted in Fig. 10. The support 8 supports the roll 9 at both ends of the roll 9. In this embodiment, the support 8 comprises an opening for each end of the roll 9, which openings are open at the upper end to receive a respective shaft portion of a shaft 1 1 of the roll 9 and to define a rotation axis RA1 for the roll 9.
Provided near the filter medium leaving side wall 6, and in this case attached to the receptacle itself, is a filter medium drawing device 20. The filter medium drawing device 20 comprises in this embodiment a first drive roll 21 with a rotation axis RA2 and a second drive roll 22 with a rotation axis RA3 in opposite arrangement with respect to each other.
As can be best seen in Fig. 10, the distance between the first and second drive roll 21 , 22 is small enough to clamp the filter medium 10 in between the two drive rolls 21 , 22 to be moveable due to friction with the drive rolls 21 , 22. In order to improve the clamping action, the first and second drive rolls 21 ,22 is provided with rings of teeth that are pressed into the filter medium for grip.
The filter medium drawing device 20 is in this embodiment covered by a cover 210 to prevent undesired access to the filter medium drawing device 20 thereby reducing the risk of accidents with the filter medium drawing device. The cover 210 may be removable for maintenance or repair purposes and/or for inserting or removing filter medium. In the side view of Fig. 10, the cover 210 is partially transparent to show the filter medium drawing device 20. To keep the filter medium 10 in close proximity of the bottom 3 and the guiding side walls 7a, 7b, also when the filter medium drawing device 20 applies a tensional force to the filter medium to draw the filter medium through the receptacle, the system comprises a first guide 30 arranged at the filter medium entering side wall 5 and a second guide 40 arranged at the filter medium leaving side wall 6. These first and second guide are similar to the first and second guide of the embodiment of Figs. 1-8. In Figs. 9 and 10, the first and second guide 30, 40 are shown in the operational position. Although in the embodiment of Figs. 1-8, only one set of supports 200 for a corresponding supply system of liquid to be filtered is shown, it is envisaged that a plurality of supports 200, e.g. two sets of supports 200 are provided to allow two or more supply systems of liquid to be filtered to be connected to the filtering system. This is shown in the
embodiment of Figs. 9 and 10.
In Figs. 9 and 10, two supply systems are partially depicted in which each supply system in this embodiment comprises a tube 220 received in and supported by a set of supports 200, wherein substantially half way, the tube comprises an exit opening 230 to allow liquid to be filtered to leave the tube and access the receptacle. This is shown in Fig. 10 for the left most tube 220 by omitting a portion of the guiding side wall 7b. In this embodiment, the exit opening 230 is provided at a distance below the tube 220 to be as close to the bottom 3 of the receptacle 1 as possible. Using a plurality of supply systems allows to more evenly distribute the liquid on the filter medium and allows to supply a higher volume of liquid per time period thereby increasing the throughput.
Shown in Fig. 9 are two level sensors 240a, 240b configured to measure a liquid level in the receptacle. One level sensor, e.g. level sensor 240a, can for instance be used to provide a signal representative for the amount of clogging of the filter medium in the receptacle while the other level sensor, e.g. level sensor 240b, can for instance be used to provide a signal allowing to determine whether the receptacle is overflowing. The level sensors 240a, 240b may for instance be a float switch each switching at different levels of liquid in the receptacle, e.g. one level indicating that filter medium is clogged and needs to be replaced and another, higher, level indicating that the receptacle is overflowing or that there is a high risk that an overflow will occur if no countermeasures are taken.
Also shown in Fig. 9 is a sensor 250 configured to detect an amount of filter medium still present on the roll 9. The sensor 250 may be configured to engage with an outer surface of the filter medium on the roll and be embodied as a switch in which a discrete signal is outputted by the sensor 250 to indicate that the diameter of the filter medium roll is larger than a predetermined value and thus there is still sufficient filter medium present to continue operation of the system, and in which another discrete signal is outputted by the sensor 250 when the diameter of the filter medium roll is below a predetermined value and thus the filter medium roll needs to be replaced any time soon.

Claims

C L A I M S
A system for filtering a liquid, comprising:
a support for a roll with filter medium;
a rectangular receptacle having a bottom with one or more through-holes for the passage of filtered liquid and four side walls which in use extend obliquely upwards and away from the bottom, said four side walls including a filter medium entering side wall, a filter medium leaving side wall opposite the filter medium entering side wall, and two guiding side walls extending on opposite sides of the bottom between the filter medium entering side wall and the filter medium leaving side wall;
a filter medium drawing device arranged at or near the filter medium leaving side wall of the receptacle to draw filter medium through the receptacle;
a first guide arranged at the filter medium entering side wall; and
a second guide arranged at the filter medium leaving side wall,
wherein the support is able to support a roll with filter medium having a width that is larger than a width of the bottom,
wherein the support is arranged at the filter medium entering side wall of the receptacle,
wherein the first and second guide are moveable between an operational position, in which they are able to guide filter medium in close proximity over the bottom and the guiding side walls, and a non-operational position at a distance from the receptacle, in which filter medium can be introduced through the receptacle to the filter medium drawing device without interference from the first and second guide, and wherein the first and second guide are configured to keep the filter medium in close proximity of the bottom and the guiding side walls when the filter medium drawing device draws filter medium through the receptacle.
A system according to claim 1 , further comprising a level sensor to measure a liquid level in the receptacle.
A system according to claim 2, further comprising a control unit to control the filter medium drawing device in dependency of an output of the level sensor.
A system according to any of the claims 1-3, further comprising a sensor configured to detect an amount of filter medium present on the roll.
A system according to any of the claims 1-4, wherein the first and/or second guide can be locked in the operational position to keep the filter medium in close proximity of the bottom and the guiding side walls.
6. A system according to any of the claims 1-5, wherein the first guide comprises a plate arranged parallel to the filter medium entering side wall in the operational position, which plate has a similar shape and dimensions seen in the width direction as the portion of the filter medium entering side wall it faces.
7. A system according to claim 6, wherein the plate of the first guide comprises an extension at the bottom side of the plate which extends parallel to the bottom of the receptacle in the operational position.
8. A system according to claim 6 or 7, wherein the plate of the first guide comprises extensions at the guiding side walls sides of the plate which extend parallel to the corresponding guiding side walls.
9. A system according to any of the claims 1-9, wherein the second guide comprises a plate arranged parallel to the filter medium leaving side wall in the operational position, which plate has a similar shape and dimensions seen in the width direction as the portion of the filter medium leaving side wall it faces.
10. A system according to claim 9, wherein the plate of the second guide comprises an extension at the bottom side of the plate which extends away from the bottom of the receptacle in the operational position.
1 1. A system according to claim 9 or 10, wherein the plate of the second guide
comprises extensions at the guiding side walls sides of the plate which extend away from the corresponding guiding side walls.
12. A system according to any of the claims 1-1 1 , wherein the filter medium drawing device comprises two drive rolls in opposite arrangement, wherein the filter medium is to be clamped in between the two drive rolls in order to be moved due to friction with the drive rolls, and wherein at least one drive roll is rotationally driveable.
13. A system according to any of the claims 1-12, wherein the system includes a roll with filter medium supported by the support, wherein the width of the filter medium is larger than the width of the bottom.
14. A method for operating the system according to claim 1 , comprising the following steps:
a) providing the system with the first and second guide in the operational position and a roll with filter medium on the support, wherein filter medium extends between the roll and the filter medium drawing device while being in close proximity of the bottom and guiding side walls of the receptacle;
b) supplying liquid to the receptacle to be filtered by the filter medium;
c) monitoring a liquid level in the receptacle; and d) driving the filter medium drawing device when the liquid level is above a predetermined level to draw the filter medium through the receptacle.
15. A method for replacing an empty or nearly empty roll with a filled roll with filter medium in a system according to claim 1 , comprising the following steps:
a) providing the system with the first and second guide in the operational position and a roll with filter medium on the support, wherein filter medium extends between the roll and the filter medium drawing device while being in close proximity of the bottom and guiding side walls of the receptacle;
b) monitoring the amount of filter medium on the roll; and
c) when the amount of filter medium on the roll is below a predetermined value, carrying out the following sub-steps:
i. moving the first and second guide to the non-operational position; ii. removing the roll and the filter medium;
iii. installing a new roll filled with filter medium;
iv. introducing the filter medium from the new roll in the receptacle and to the filter medium drawing device; and
v. moving the first and second guide to the operational position.
PCT/NL2017/050703 2016-11-01 2017-11-01 System for filtering a liquid, method for operating such a system and roll replacement method WO2018084701A1 (en)

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US10724029B2 (en) 2012-03-15 2020-07-28 Flodesign Sonics, Inc. Acoustophoretic separation technology using multi-dimensional standing waves
US11214789B2 (en) 2016-05-03 2022-01-04 Flodesign Sonics, Inc. Concentration and washing of particles with acoustics

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NL2028973B1 (en) 2021-02-26 2022-09-20 Aqua D En S B V A portable separation station and method for filtering water

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US3757949A (en) 1971-06-24 1973-09-11 Catborundum Co Liquid filter device
GB2175796A (en) * 1985-05-30 1986-12-10 Chojoha Giken Kk Frier incorporating filtering mechanism
US5177335A (en) * 1990-01-16 1993-01-05 Westhoff Machine Company Prefilter for EDM machine

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Publication number Priority date Publication date Assignee Title
US10724029B2 (en) 2012-03-15 2020-07-28 Flodesign Sonics, Inc. Acoustophoretic separation technology using multi-dimensional standing waves
US11214789B2 (en) 2016-05-03 2022-01-04 Flodesign Sonics, Inc. Concentration and washing of particles with acoustics

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