DEVICE AND METHOD FOR SIMULTANEOUSLY PRODUCING SEPARATE FILTRATES FROM A SINGLE SUBSTRATE

Abstract

The present invention relates to a filtration device comprising: at least one enclosure (1; 1A, 1B; 1A, 1B, 1C, 1D) defining a longitudinal axis, said enclosure being obstructed at each end by at least one sealing plate (2A, 2B; 2C, 2D), at least one filtration disc (4) that is rotated and at least one spacer (10) placed between each filtration disc (4), said spacer (10) defining an inter-disc space (10A), at least one hollow rotation shaft (3; 3A) that rotates said at least one filtration disc (4), said shaft having at least one port (33) adapted to collect filtrate (11A, 11B), said filtration disc (4) and said spacer (10) being arranged on said at least one rotation shaft (3; 3A, 3B) inside said enclosure (1; 1A, 1B; 1A, 1B, 1C , 1D), characterised in that said enclosure (1; 1A, 1B; 1A, 1B, 1C, 1D) is passed through by said at least one rotation shaft (3; 3A), and said rotation shaft (3; 3A) is driven by at least one separate rotation means (5, 5A, 5B, 5C) on at least one of the ends of said shaft, said rotation means and said rotation shaft being coaxial, and in that the device comprises at least two separate discharge means (13A, 13B) for the filtrate (11A, 11B), said discharge means being located on said rotation shaft outside said enclosure.

Claims

1. A filtration device, comprising: at least one enclosure (1; 1A, 1B; 1A, 1B, 1C, 1D) defining a longitudinal axis, said enclosure being obstructed at each end by at least one sealing plate (2A, 2B; 2C, 2D), at least one filtration disc (4) that is rotated and at least one spacer (10) placed between each filtration disc (4), said spacer (10) defining an inter-disc space (10A), at least one hollow rotation shaft (3; 3A) rotating said at least one filtration disc (4), said rotation shaft having at least one port (33) adapted to collect filtrate (11A, 11B), said filtration disc (4) and said spacer (10) being arranged on said at least one rotation shaft (3; 3A, 3B) inside said enclosure (1; 1A, 1B; 1A, 1B, 1C , 1D), characterised in that said enclosure (1; 1A, 1B; 1A, 1B, 1C, 1D) is passed through by said at least one rotation shaft (3; 3A), and said rotation shaft (3; 3A) is driven by at least one separate rotation means (5, 5A, 5B, 5C) on at least one of the ends of said shaft, said rotation means and said rotation shaft being coaxial, and in that the device comprises at least two separate discharge means (13A, 13B) for the filtrate (11A, 11B), said discharge means being located on said rotation shaft outside said enclosure.

2. The device according to claim 1, in which a single rotation shaft (3; 3A) is present inside said enclosure, a shutter (15) being placed inside said rotation shaft dividing said rotation shaft into two separate parts (30A, 30B), each separate part conducting a different filtrate (11A, 11B) in opposite directions towards said discharge means (13A, 13B), said shutter being adapted to prevent the different filtrates from mixing.

3. The device according to claim 2, in which the two separate parts (30A, 30B) are each delimited on the one hand by the position of one of the discharge means (13A, 13B) for the filtrate (11A, 11B) on the rotation shaft (3; 3A) and on the other hand by the position of the shutter (15), and the two separate parts (30A, 30B) are each of the same or different size depending on the position of the shutter (15) inside the rotation shaft.

4. The device according to claim 2, in which each separate part (30A, 30B) of said rotation shaft has at least one of said port (33) adapted to conduct said filtrate (11A, 11B) from the spacer (10) towards the inside of said rotation shaft.

5. The device according to claim 3, in which a single rotation shaft (3; 3A) is present inside said enclosure, the recovery of the filtrate (11A, 11B) being carried out in two separate parts (30A, 30B) of said rotation shaft, each separate part conducting a different filtrate (11A, 11B) in opposite directions towards said discharge means (13A, 13B), the two separate parts (30A, 30B) each being delimited on the one hand by discharge means (13A, 13B) for the filtrate (11A, 11B) and on the other hand by the position of the shutter.

6. The device according to claim 1, in which two rotating shafts (3; 3A) are present inside said enclosure, the collection of the filtrate (11A, 11B) is carried out in two separate parts (16A, 16B) within said enclosure, each separate part (16A, 16B) evacuating a different filtrate (11A, 11B) in opposite directions towards said discharge means (13A, 13B), and the two separate parts (16A, 16B) are each delimited on the one hand by one of the discharge means (13A, 13B) for the filtrate (11A, 11B) and on the other hand by the distal end of each rotation shaft inside the enclosure.

7. The device according to claim 1, in which said enclosure (1; 1A, 1B; 1A, 1B, 1C, 1D) is passed through by at least two separate rotation shafts (3; 3A, 3B) arranged successively in said enclosure, and each of said rotation shafts (3; 3A, 3B) is driven by at least one separate rotation means (5, 5A, 5B, 5C), said rotation means being coaxial and said rotation shafts being separated axially from each other, and in which the device comprises at least one discharge means (13A, 13B) for the filtrate (11) per rotation shaft, each discharge means being located on said rotation shaft outside said enclosure.

8. The device according to claim 7, in which said at least at least one separate rotation means (5, 5A, 5B, 5C) is located outside said enclosure and at the end of each of said shafts.

9. The device according to claim 1, in which said discharge means are located on said rotation shaft either between said sealing plate and the proximal end of said rotation means, or at the distal end of said rotation means.

10. The device according to claim 1, in which a space (10A) between said enclosure (1; 1A, 1B; 1A, 1B, 1C, 1D) and the filtration disc (4) is between 10 mm and 400 mm.

11. The device according to claim 10, in which the length of the inter-disc space (10A) varies between 4 mm and 10 mm and a seal (99) is housed therein.

12. The device according to claim 1, in which the introduction means (6; 6A, 6B) for the liquid to be filtered (8) is connected to said sealing plate (2; 2A, 2B) and the outlet means (7) for the concentrate (12) is connected at a point located between the inner ends of the shafts (3; 3A, 3B) located in the enclosure.

13. The device according to claim 1, in which the introduction means (6; 6A, 6B) for the liquid to be filtered (8) is connected to one of the sealing plates (2; 2A, 2B) and the outlet means (7) for the concentrate (12) is connected to the opposite sealing plate (2; 2A, 2B).

14. The device according to claim 1, in which said filtration discs (4) are divided into a plurality of groups, the cut-off thresholds of which are chosen independently of each other to allow simultaneous obtainment of filtrates (11A, 11B) obtained with different cut-off thresholds.

15. A filtration method implemented by the device defined in claim 1, wherein said method comprises the following steps: introducing the liquid to be filtered (8) by at least one introduction means (6; 6A, 6B), rotating at least one rotation shaft (3; 3A, 3B) by at least one rotation means (5A, 5B, 5C) separate from at least one of the ends of said rotation shaft, filtering said liquid to be filtered (8) by passing it through at least one filtration disc (4), obtaining a concentrate (12) inside the enclosure (1; 1A, 1B; 1A, 1B, 1C, 1D), discharging said concentrate (12) from said enclosure (1; 1A, 1B; 1A, 1B, 1C, 1D) by the outlet means (7) for said concentrate (12), obtaining a filtrate (11A, 11B) collected by at least one port (33) located on said at least one rotation shaft (3; 3A, 3B) that is axial relative to said enclosure (1; 1A, 1B; 1A, 1B, 1C, 1D), discharging the filtrate (11A) by a first discharge means (13A) and the filtrate (11B) by a second discharge means (13B), said means being located on said rotation shaft outside said enclosure.

16. The filtration method according to claim 15, wherein said method comprises at least the following steps: introducing the liquid to be filtered (8) by at least one introduction means (6; 6A, 6B), rotating at least two rotation shafts (3; 3A, 3B) arranged successively in said enclosure and separated from each other, each rotation shaft being driven by at least one separate rotation means (5A, 5B, 5C), said rotation means being coaxial, filtering said liquid to be filtered (8) by passing it through at least one filtration disc (4), obtaining a concentrate (12) inside the enclosure (1; 1A, 1B; 1A, 1B, 1C, 1D), discharging said concentrate (12) from said enclosure (1; 1A, 1B; 1A, 1B, 1C, 1D) by the outlet means (7) for said concentrate (12), obtaining a filtrate (11A, 11B) collected by at least one port (33) located on at least one rotation shaft (3; 3A, 3B) that is axial relative to said enclosure (1; 1A, 1B; 1A, 1B, 1C, 1D), discharging the filtrate (11A) by a first discharge means (13A) and the filtrate (11B) by a second discharge means (13B), said means being located on said rotation shaft outside said enclosure.

Description

DETAILED DESCRIPTION OF THE DRAWINGS

[0095] FIG. 1 shows a first embodiment of the device of the present invention comprising 2 rotation shafts and 2 rotation means (motors) and 1 enclosure. The enclosure is formed of an enclosure closed on each side by an end plate passed through by a half shaft, the filtration discs being threaded on said half shaft. The liquid filtered by the discs is collected and evacuated through the centre of the shaft towards the outside of the enclosure. The two shafts can be rotated in the same direction or in opposite directions. The two shafts can have different rotational speeds. Both shafts can be fitted with the same number of discs or with a different number of discs.

[0096] FIG. 2 shows a second embodiment of the device of the present invention comprising 1 rotation shaft and 2 rotation means (motors) and 1 enclosure. The enclosure consists of a tube closed on each side by an end plate, said plates being passed through by a single shaft, the filtration discs being threaded on said shaft. The liquid filtered by the discs is collected and evacuated through the centre of the shaft towards the outside of the enclosure at least at one of the two ends. The setting in motion of the shaft is ensured by a specific means at each end.

[0097] FIG. 3 shows a third embodiment of the device of the present invention comprising 2 rotation shafts substantially parallel to one another, 1 rotation means (motor) and 2 enclosures.

[0098] The installation is formed of several enclosures. Each enclosure is formed of a tube closed on each side by an end plate passed through by a single shaft, the filtration discs being threaded on said shaft. The liquid filtered by the discs is collected and evacuated through the centre of the shaft towards the outside of each enclosure at least at one of the two ends. The setting in motion of the shaft of each enclosure at each end is ensured by a single means linked mechanically or hydraulically to each enclosure.

[0099] FIG. 4 shows a fourth embodiment of the device of the present invention comprising 2 independent rotation shafts that are substantially parallel to each other and 1 rotation means (motor) and 2 enclosures. This unique device for setting in motion acts at all the ends of each enclosure, possibly common to one or more enclosure(s) and several independent rotation axes. The installation consists of several enclosures (2, 3 or 4 enclosures). Each enclosure is formed of a tube closed on each side by an end plate passed through by a half shaft, the filtration discs being threaded on said half shaft. The liquid filtered by the discs is collected and evacuated through the centre of the shaft to the outside of each enclosure. The two shafts of each enclosure can be rotated in the same direction or in opposite directions. The two shafts of each enclosure can have different rotational speeds. The two shafts of each enclosure can be equipped with the same number of discs or with a different number of discs. The setting in motion of each shaft at each end of each enclosure is ensured by a single means linked mechanically or hydraulically to each enclosure

[0100] FIG. 5 shows a fifth embodiment of the present invention comprising 1, 2, 3 or 4 rotation shaft(s) and 3 rotation means (motors) and 4 axial enclosures. The device can have 1, 2, 3 or 4 or more enclosures and several rotation axes and shares one or more driving devices for setting in motion two, three or four or more enclosures.

[0101] FIG. 6 shows a comparison between the single-motor device and the twin-motor device.

[0102] FIG. 7 shows the torque and power in comparison with the speed of rotation.

[0103] FIG. 8 shows the impact of changing the rotation speed from 284 rpm to 320 rpm on the torque in Nm.

[0104] FIG. 9 shows the impact of changing the rotation speed from 284 rpm to 320 rpm on the permeation flow.

[0105] FIG. 10 shows the viscosity of the incoming product as a function of the shear rate.

[0106] FIG. 11 shows the viscosity of the incoming product as a function of the shear rate with 10 times higher viscosity of the concentrate. The product leaving the device is much more concentrated than the product entering the device.

[0107] FIG. 12 shows a sectional view of the interior of an enclosure comprising at least one spacer (10), at least one seal (99), one rotation (or drive) shaft (3) and at least one filtration disc (4).

[0108] FIG. 13 shows a sectional view of the interior of an enclosure comprising two means of rotation (5A, 5B), the means of introduction (6) of the liquid to be filtered, the outlet means (7) for the concentrate (dirty liquid) by an end plate (2B) and the discharge means for the filtrate (clean liquid) (13A, 13B). The discharge means (13A) for the filtrate operates in the rotation shaft (3A) and the discharge means (13B) for the filtrate operates in the rotation shaft (3B).

[0109] FIG. 14 shows a sectional view of the interior of an enclosure comprising two rotation means (5A, 5B), the means of introduction (6) of the liquid to be filtered, the elongate outlet means (7) for the concentrate (dirty liquid) by an end plate (2B) and the discharge means for the filtrate (clean liquid) (13A, 13B). The discharge means (13A) for the filtrate operates in the rotation shaft (3A) and the discharge means (13B) for the filtrate operates in the rotation shaft (3B).

[0110] FIG. 15 shows a first rotation shaft (3A) and a second rotation shaft (3B), the two rotation shafts being coaxial and physically separated, as well as a rotation means (motor) located at the end, outside the enclosure (1), of each shaft. The discharge means (13A) for the filtrate operates in the first rotation shaft (3A) and the discharge means (13B) for the filtrate operates in the second rotation shaft (3B), said discharge means being located on said rotation shaft between said sealing plate and said rotation means. The liquid to be filtered is introduced by the introduction means (6). As they move towards the outlet means (7), the solids concentrate and increase the viscosity. The increase in viscosity leads to an increase in friction forces, which results in an increase in the torque causing the discs to rotate. The mechanical limits of the rotor, the centre of which must be hollow to allow the discharge of the filtrate, and the outside which must have the smallest possible diameter, are decoupled using the device of the present invention. In fact, the discs on the side on which the product is introduced require less torque, while those on the concentrate discharge side require more. The invention also makes it possible to rotate the discs located on separate rotation shafts at different speeds or even with opposite directions of rotation, which increases the turbulence and therefore the self-cleaning of the membranes.

[0111] FIG. 15 also shows two separate rotation shafts (3A, 3B), a motor connected to each rotation shaft, as well as two zones (14A, 14B) with distinct hydrodynamic conditions within the enclosure. A substrate is introduced by the introduction means (6), then the substrate is filtered at said filtration discs (4); the separate filtrates (11A, 11B) discharged simultaneously from the same substrate will be conducted from the spacer (10) towards the inside of each rotation shaft and are discharged in opposite directions towards one of the discharge means (13A, 13B). The solids are then moved to the solids outlet means (7).

[0112] FIG. 16 shows a single rotation shaft (3A), a motor connected to each end of the rotation, shaft as well as two zones (14A, 14B) with distinct hydrodynamic conditions within the enclosure. A substrate is introduced by the introduction means (6), then said substrate is filtered at said filtration discs (4), generating separate filtrates (11A, 11B) discharged simultaneously from the same substrate and which will be conducted from the spacer (10) towards the inside of each separate part (30A, 30B) of said rotation shaft containing a shutter (15) inside. Said separate filtrates (11A, 11B) are discharged in opposite directions towards one of the discharge means (13A, 13B). The solids are then moved to the outlet means (7).

[0113] The present invention is also applicable in the case where several rotation shafts are mounted in parallel within the same enclosure. The number of axial or parallel enclosures is unlimited (at least 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or more enclosures).

[0114] The advantages of the present invention is that it makes it possible: [0115] to increase by at least 50% the quantity of membrane discs used per casing (or enclosure) for a given speed of rotation. [0116] to increase by at least 50% the discharge flow of the filtrate obtained on the membrane discs with identical or lower pressure drop.

[0117] When the concentration of the product to be filtered increases, its viscosity also increases.

[0118] This results in an increase in friction on the rotating filtration discs, which requires a greater rotational force. As a result, the torque increases.

[0119] Since the power of the motor-variator (4 Kw) which drives the rotation shaft is limited, when it reaches its maximum power, and the necessary torque continues to increase, the motor decreases its rotation speed (the limit of a motor is fixed by the amperage which circulates in the coils, which can be of 8.6 A for 4 Kw). In one embodiment, an MT 430 motor has a rotation setpoint at 40 Hz (40 Hz at a rotation speed of 284 rpm) but the motor, in order not to exceed its characteristics, maintains a maximum current at 8.6 A. To do this, it is possible to decrease the rotation speed from 40 Hz to 29 Hz. This has the indirect effect of reducing the permeation flow of the installation.

TABLE-US-00001 Comparative tests Criteria & Standards Present invention Current standard (single motor) Maximum speed on horizontal enclosure of 6 m (standard) rpm 350 210 Maximum allowable viscosity (at maximum enclosure speed) 20-50 × (water) (Vmax 350 rpm) 2-5 × (water) (Vmax 210 rpm) Number of horizontal enclosures for a surface of 35-50 m.sup.2 (depending on space between discs) number 2 bottom plates (2 motors, 0 opposite plate) 1 of 6 m

[0120] The present invention makes it possible to increase maximum admissible viscosity by a factor of 10.

TABLE-US-00002 CHARACTERISTICS units Known single-motor enclosure Present invention with enclosure asymmetric twin-motor Present invention with enclosure symmetrical twin-motor Main gear membrane blocks number 5 3 3 Membrane blocks of the second gear number - 2 2 Main gear motor power kW 4 3 3 Second gear motor power kW - 2 3 Torque at 50 Hz, 260 rpm on main gear Nm/disc 0.64 0.8 0.8 Torque at 50 Hz, 260 rpm on second gear Nm/disc - 0.8 1.2 maximum concentration MS main gear g/kg 65 90 90 maximum concentration MS second gear g/kg - 90 140 input raw material quantity kg/h 1000 1000 1000 MS concentration at input g/kg 45 45 45 retentate outlet kg/h 692 500 321 permeate outlet kg/h 308 500 679 Yield kg permeate/kwh 90 118 133 Yield gain % - 31 48

[0121] Table 2 shows that the present invention comprising an asymmetric twin-motor enclosure has an efficiency gain of 31% (118-90 = 28, if 90 =100% then 28 =31%).

[0122] Table 2 shows that the present invention comprising a symmetrical twin-motor enclosure has an efficiency gain of 48% (133-90 = 43, if 90 =100% then 43 =48%).

TABLE-US-00003 Comparison between the prior art and the present invention Frequency (Hz) Rotation speed of the filtering rotation shaft in rpm Maximum torque in Nm Motor power in Watt Torque per disc - prior art for 3x36 discs in Nm Torque per disc - present invention for 2×36 discs in Nm Torque per disc - present invention for 1×36 discs in Nm 20 117 84.5 1031 0.78 1.17 2.35 35 202 131.3 2780 1.22 1.82 3.65 50 289 131.2 4000 1.21 1.82 3.64 60 347 121 4400 1.12 1.68 3.36

[0123] In Table 3 (to be read with FIG. 15), the increase in viscosity leads to an increase in the friction forces which results in an increase in the torque causing the discs to rotate.

[0124] The mechanical limits of the rotation shaft, the centre of which must be hollow to allow discharge of the filtrate and the exterior of which must have the smallest possible diameter, are decoupled using the device of the present invention.

[0125] In fact, the discs on the product introduction side require less torque, while those on the discharge side of the concentrate require more.

[0126] The invention also makes it possible to rotate the discs located on separate rotation shafts at different speeds or even with opposite directions of rotation, which increases the turbulence and therefore the self-cleaning of the membranes.

[0127] The liquid to be filtered is introduced by the introduction means (6). As it moves towards the outlet means (7), the solid matter concentrates and increases the viscosity of the fluid.

[0128] In the last column of Table 3 the torque per disc of the present invention is multiplied by about 3 compared to the torque per disc of the prior art, which makes it possible to process products which are much more viscous and therefore more concentrated.

[0129] Other implementations are possible:

[0130] For example a distribution of 4 blocks/1 block between the two sets of membranes (instead of 3 & 2 as shown in Table 2)

[0131] For example with more powerful motors within the torque limit of each of the axes, for example 4 & 3 kW (asymmetrical) or 4 & 4 kW (symmetrical)

[0132] For example with other motor frequencies (40-60 Hz) and other rotational speeds (100-500 rpm).

[0133] Certain features of the invention which are described as separate embodiments can also be provided in combination in a single embodiment. In contrast, certain features of the invention which are described as an embodiment in combination in a single embodiment can also be provided separately in the form of several separate embodiments.