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 defining a longitudinal axis, said at least one enclosure being obstructed at each end by at least one sealing plate; a plurality of filtration discs that are rotated; at least one spacer disposed between each of two of the plurality of filtration discs, said at least one spacer defining an inter-disc space; at least one hollow rotation shaft rotating said plurality of filtration discs, said at least one rotation shaft having at least two ports configured to collect different filtrate from the at least one spacer toward an interior of the at least one hollow rotation shaft, the at least one hollow rotation shaft passing through the at least one enclosure, said plurality of filtration discs and said at least one spacer being arranged on said at least one hollow rotation shaft inside said at least one enclosure, said at least one hollow rotation shaft being driven by at least one separate rotation device on at least one end of the plurality of ends of said at least one hollow rotation shaft, said at least one separate rotation device and said respective at least one hollow rotation shaft being coaxial; and at least two separate discharge devices configured to respectively discharge the different filtrate collected by a respective port of the at least two ports, said at least two separate discharge devices being disposed on said at least one hollow rotation shaft outside said at least one enclosure and upstream of said at least one separate rotation device.

2. The filtration device according to claim 1, wherein the at least one hollow rotation shaft is a single rotation shaft that is present inside said at least one enclosure, a shutter being disposed inside said single rotation shaft dividing said single rotation shaft into two separate parts, each of the two separate parts respectively conducting the different filtrate in opposite directions towards said discharge devices, said shutter being configured to prevent the different filtrates from mixing.

3. The filtration device according to claim 2, wherein the two separate parts are each delimited by the position of one of the discharge devices for the respective different filtrate on the single rotation shaft and a position of the shutter, and the two separate parts are each of the same or different size depending on a position of the shutter inside the single rotation shaft.

4. The filtration device according to claim 2, wherein each of the two separate parts of said single rotation shaft has at least one of said at least two ports configured to conduct said respective different filtrate from the at least one spacer towards the inside of said single rotation shaft.

5. The filtration device according to claim 3, wherein recovery of the different filtrate being carried out in the respective two separate parts of said single rotation shaft, each of the separate parts conducting the respective different filtrate in opposite directions towards said respective discharge devices, the two separate parts each being delimited by the respective discharge device for the respective different filtrate and by the position of the shutter.

6. The filtration device according to claim 1, wherein the at least one hollow rotation shaft comprises two hollow rotation shafts present inside said at least one enclosure, collection of the different filtrate being carried out in two separate parts within said at least one enclosure, each of the two separate parts evacuating the different filtrate in opposite directions towards said at least two separate discharge devices, and the two separate parts are each delimited by one of the two separate discharge devices for the different filtrate and a distal end of each of the two hollow rotation shafts inside the at least one enclosure.

7. The filtration device according to claim 1, wherein the at least one hollow rotation shaft includes at least two separate hollow rotation shafts disposed successively in the at least one enclosure and passing through said at least one enclosure, each of said at least two separate hollow rotation shafts being driven by at least one separate rotation device, said at least one separate rotation device of each of the at least two separate hollow rotation shafts being coaxial with respect to one another, said at least two separate rotation shafts being separated axially from each other, wherein at least one discharge device of the at least two separate discharge devices is provided per each one of the at least two separate hollow rotation shafts, each of the at least two separate discharge devices being disposed on said respective hollow rotation shaft outside said at least one enclosure.

8. The filtration device according to claim 7, wherein said at separate rotation device is disposed outside said at least one enclosure and at an end of each of said at least two separation hollow rotation shafts.

9. The filtration device according to claim 1, wherein said at least two separate discharge devices are disposed on said at least one hollow rotation shaft either between said at least one sealing plate and a proximal end of said at least one separate rotation device, or at a distal end of said at least one separate rotation device.

10. The filtration device according to claim 1, wherein a space between said at least one enclosure and at least one of the filtration discs is between 10 mm and 400 mm.

11. The filtration device according to claim 10, wherein a length of the inter-disc space varies between 4 mm and 10 mm and a seal is housed therein.

12. The filtration device according to claim 1, wherein the at least one hollow rotation shaft comprises at least two hollow rotation shafts, the device further comprises an introduction system configured to introduce the liquid to be filtered, the introduction system being connected to said at least one sealing plate, an outlet for the concentrate being connected at a point located between respective inner ends of the at least two hollow rotation shafts located in the at least one enclosure.

13. The filtration device according to claim 1, further comprising an introduction system configured to introduce the liquid to be filtered, the introduction system being connected to one of the at least one sealing plate, an outlet for the concentrate being connected to an opposite sealing plate that is opposite the one sealing plate.

14. The filtration device according to claim 1, wherein said plurality of filtration discs are divided into a plurality of groups, cut-off thresholds of the plurality of filtration discs being selected independently of each other to allow simultaneous obtainment of filtrates obtained with different cut-off thresholds.

15. A filtration method implemented by a device including at least one enclosure defining a longitudinal axis, said at least one enclosure being obstructed at each end by at least one sealing plate, a plurality of filtration discs that are each rotated, at least one spacer disposed between each of two of the plurality of filtration discs, said at least one spacer defining an inter-disc space, at least one hollow rotation shaft rotating said plurality of filtration discs, said at least one rotation shaft having at least two ports configured to collect different filtrate from the at least one spacer toward an interior of the at least one hollow rotation shaft, the at least one hollow rotation shaft passing through the at least one enclosure, said plurality of filtration discs and said at least one spacer being arranged on said at least one hollow rotation shaft inside said at least one enclosure, said at least one hollow rotation shaft being driven by at least one separate rotation device on at least one end of the plurality of ends of said at least one hollow rotation shaft, said at least one separate rotation device and said respective at least one hollow rotation shaft being coaxial, at least two separate discharge devices configured to respectively discharge the different filtrate collected by a respective port of the at least two ports, said at least two separate discharge devices being disposed on said at least one hollow rotation shaft outside said at least one enclosure and upstream of said at least one separate rotation device, and at least one introduction system configured to introduce liquid to be filtered, said method comprising: introducing the liquid to be filtered by the at least one introduction system; rotating the at least one hollow rotation shaft by at least one rotation device separate from at least one of ends of said at least one hollow rotation shaft; filtering said liquid to be filtered by passing the liquid through at least one of the filtration discs; obtaining a concentrate inside the enclosure; discharging said concentrate from said enclosure by at least one outlet for said concentrate; obtaining the different filtrate collected by the at least two ports located on said at least one rotation shaft that are axial relative to said enclosure; discharging the respective different filtrate by a first discharge device a second discharge device, said first and second discharge devices being disposed on said at least one rotation shaft outside said enclosure and upstream of said at least one rotation device.

16. The filtration method according to claim 15, further comprising: wherein the at least one rotation shaft comprises at least two rotation shafts, and the rotating the at least one rotation shaft comprises rotating the at least two rotation shafts disposed successively in said enclosure and separated from each other, each of the at least two rotation shafts being driven by at least one separate rotation device, said rotation devices being coaxial, filtering said liquid to be filtered (8) by passing it through at least one filtration disc (4).

Description

DETAILED DESCRIPTION OF THE DRAWINGS

(1) 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.

(2) 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.

(3) 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. 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.

(4) 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

(5) 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.

(6) FIG. 6 shows a comparison between the single-motor device and the twin-motor device.

(7) FIG. 7 shows the torque and power in comparison with the speed of rotation.

(8) FIG. 8 shows the impact of changing the rotation speed from 284 rpm to 320 rpm on the torque in Nm.

(9) FIG. 9 shows the impact of changing the rotation speed from 284 rpm to 320 rpm on the permeation flow.

(10) FIG. 10 shows the viscosity of the incoming product as a function of the shear rate.

(11) 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.

(12) 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).

(13) 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).

(14) 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).

(15) 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.

(16) 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).

(17) 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).

(18) 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).

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

(20) When the concentration of the product to be filtered increases, its viscosity also increases.

(21) This results in an increase in friction on the rotating filtration discs, which requires a greater rotational force. As a result, the torque increases.

(22) 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.

(23) TABLE-US-00001 TABLE 1 Comparative tests: Criteria & Present Current standard Standards invention (single motor) Maximum speed on horizontal rpm 350 310 enclosure of 6 m (standard) Maximum allowable viscosity 20-50? 2-5? (water) (at maximum enclosure speed) (water) (Vmax 210 rpm) (Vmax 350 rpm) Number of horizontal enclosures number 2 bottom plates enclosures for a surface of (2 motors, 0 35-50 m.sup.2 (depending opposite plate) on space between discs) 1 of 6 m

(24) The present invention makes it possible to increase maximum admissible viscosity by a factor of 10.

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

(26) 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%).

(27) 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%).

(28) TABLE-US-00003 TABLE 3 comparison between the prior art and the present invention. Rotation Torque per Torque per speed of the Torque per disc-present disc-present filtering disc-prior invention for invention for Frequency rotation shaft Maximum Motor power art for 3 ? 36 2 ? 36 discs in 1 ? 36 discs in (Hz) in rpm torque in Nm in Watt discs in Nm Nm 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

(29) 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.

(30) 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.

(31) In fact, the discs on the product introduction side require less torque, while those on the discharge side of the concentrate require more.

(32) 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.

(33) 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.

(34) 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.

(35) Other implementations are possible: For example a distribution of 4 blocks/1 block between the two sets of membranes (instead of 3 & 2 as shown in Table 2) 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) For example with other motor frequencies (40-60 Hz) and other rotational speeds (100-500 rpm).

(36) 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.