JPH0130529B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a liquid filtration device.

- a tank for containing the liquid to be filtered; - a porous tubular filter connected to said tank via a pipe, the ends forming a chamber with openings allowing the flow of the part of the liquid that has not passed through the filter; - means for maintaining the liquid under constant pressure at the inlet of the chamber; - a porous tubular filter rotatably mounted coaxially within the chamber and coupled to a motor for rotational drive; - a cylindrical casing arranged around the filter with an outlet for collecting liquid; - a cylindrical outer surface of the filter for unclogging the filter; A liquid filtration device is known from French Patent No. 156,995 (MERCK & Co. INC.), which has controllable means for causing the liquid to flow back by creating an excess counterpressure.

The object of the invention is to improve the operation of this type of device by maintaining a predetermined steady-state ratio between the liquid and non-permeable liquid flow rates.

The object of the invention is to provide: - a storage tank for the liquid to be filtered; - a porous tubular filter communicating with said tank via a pipe, the chamber having apertures for allowing the part of the liquid that has not passed through the filter to flow out; - a porous tubular filter closed at both ends to form a filter; - means for maintaining the liquid under constant pressure at the inlet of the chamber; - coaxially rotatably mounted within the chamber and driven in rotation; - a cylindrical casing arranged around the filter and provided with an outlet for collecting liquid; - a cylindrical casing for unclogging the filter; controllable means for causing liquid to flow backwards by creating a liquid counter-pressure on the cylindrical outer surface of the filter, further comprising: - a flow rate measuring device connected to said outlet; A liquid filtration device comprising: a positive displacement pump having an inlet connected to the bore; - a control system capable of adjusting the flow rate of the positive displacement pump according to the liquid flow rate measured by said flow measuring device; That's true.

The invention will be explained below in a non-limiting manner on the basis of specific examples shown in the accompanying drawings.

In FIG. 1, a liquid 1, such as milk, is contained in a tank 2. tank 2
The upper gas space of is in communication with a pressure reducing valve 3 connected to the outlet of the compressed gas cylinder 4. tank 2
The liquid 1 is in communication with the interior space of the filter cartridge 6 via a pipe 5. The cartridge 6 has a filter 8 in the shape of a rotating cylindrical body made of ceramic, for example, inside a cylindrical casing 7.
including. The casing 7 and the tube 8 are coaxial. The ends of the tube 8 are closed by two end bearings 9, 10, respectively, which are supported only by the casing 7, and the pipe 5 is closed by two end bearings 9, 10, which are supported only by the casing 7
It opens into the interior of the chamber formed by 0 and 0. The cylindrical coaxial core 11 has an end bearing member 9,
The spindle 12 is rotatably mounted on two bearing surfaces provided on the spindle 10. One end of the spindle 12 is fixed to a pulley 13 , and the pulley 13 is connected to a pulley 15 via a belt 14 , and the pulley 15 is attached to the output shaft of a drive motor 16 .

Preferably, the perforated tube 8 includes an outer tubular portion having relatively coarse pores and an inner tubular portion having fine pores. The inner part constitutes the actual permembrane, and the outer periphery functions as a support for the membrane. The outer peripheral part and the inner part are of course fixed to each other.

The interior space of the cartridge 6 contained between the filter tube 8 and the housing 7 is connected to a flow measuring device 17 via a controllable backflow system 18 and two pipes 19, 20. Device 1
7 is connected to a liquid collection tank (not shown) via a pipe 21.

The interior space of the cartridge 6 contained between the core 11 and the tube 8 collects, via a positive displacement pump 22 and two pipes 23, 24, the non-permeable liquid, i.e. the part of the liquid that has not passed through the filter tube 8. It is connected to another tank (not shown) for storage.

An auxiliary tank 25 filled with the liquid to be treated is connected to the tank 2 via a pump 26.
Finally, a control system 27 is electrically connected to the electrical control of the device 17 on the one hand and the pumps 22, 26 on the other hand.

FIG. 2 shows a specific example of the filter cartridge 6 schematically shown in FIG.

According to FIG. 2, the cylindrical casing of the cartridge consists of a tube 28 with internal threads at both ends, these threads being connected to two terminal inserts 31, 3.
2, respectively. Members 31 and 32 perform the function of end bearing members 9 and 10 in FIG. The ceramic porous tube 8 has non-porous ends 35, 36, which are connected to the annular packings 33, 3.
4 on the shoulders of the distal insertion members 31, 32. Both ends of the core 37 have two coaxial shaft end members 38, 39, which are rotatable within the terminal insertion members 31, 32 via two bearings 40, 41. is installed on.

In the embodiment shown, the core 37 has four slightly raised longitudinal vanes 42, 43, 44, 45. These vanes 42, 43, 44, 45 are shown in FIG. 3, which is a cross-sectional view of the cartridge along the - plane of FIG.

Two annular packings 46, 47 are fixed inside the end insertion members 31, 32, and when the core 37 is driven to rotate, the shaft end members 38, 39 slide against the lips of these packings 46, 47. do. An inlet tube 48 is secured to the distal insert 31 . This pipe 48 corresponds to the cartridge reaching end of the pipe 5 (FIG. 1). Similarly, an outlet tube 49 is secured to the distal insertion member 32. Pipe 49 corresponds to the starting end of pipe 23 (FIG. 1). tube 48
An outlet tube 50 is secured to the tube 28 on the opposite side. Pipe 50 corresponds to the starting end of pipe 19 (FIG. 1). The annular packings 51, 52 engage grooves provided in the distal insertion members 31, 32, and are inserted into the tube 2.
8 to ensure airtightness of the space between the tubes 8 and 28. The airtightness of the space between the core 37 and the tube 8 is ensured by the seals 33, 34,
46 and 47.

The apparatus of FIGS. 1-3, as described above, operates as follows.

The pressure of the liquid at the inlet of the cartridge 6 is maintained at a constant value. This value can be adjusted by operating the pressure reducing valve 3. Next, the motor 16 is operated to rotate the core 11 within the filter cartridge 6. The liquid to be filtered under constant pressure flows into the cartridge 6 via the pipe 5. As the core 11 rotates, the liquid between the core 11 and the filter tube 8 is subjected to a swirling movement tangentially to the inner surface of the tube 8. A portion of this liquid passes through the pores of tube 8. When the core is provided with vanes (see Figures 2 and 3)
(see figure), the turbulence of the liquid increases and the overspeed increases.

The backflow system 18 mainly comprises a cylinder containing a sliding piston and means for controlling the stroke of the piston at predetermined time intervals, causing the liquid to flow back into the cartridge 6 in the opposite direction to the normal direction of flow and through the filter. A counter-pressure is generated on the outer surface of the perforated tube 8 sufficient to remove the blockage. In particular, this counterpressure can cause solid particles that block the pores of the membrane to dislodge from the inner surface of the perforated tube 8.

During normal operation of the device, system 18 is not active, so liquid fills the space between tubes 8 and 7 and is directed to the recovery tank via pipe 19, system 18, pipe 20, device 17 and pipe 21. It flows freely. System 18 does not impede liquid flow in any way. Control system 27 receives information regarding the liquid flow rate measured by device 17 and then controls the rotation of positive displacement pump 22 to maintain a predetermined steady-state ratio between permeate and non-permeate flow rates.

As shown in FIG. 1, the control system 27 may also control the rotation of the pump 26 to maintain a predetermined flow rate of liquid supplied to the tank 2 from the auxiliary tank 25. The flow rate of the auxiliary tank 25 is selected to compensate for the total flow rate of permeate and non-permeate exiting the filter cartridge 6.

The above device has the following advantages.

Since the rotation of the core transmits high velocities to the liquid tangential to the walls of the filter, clogging caused by agglomeration of passed particles on the cylindrical inner wall of the filter is significantly reduced. Moreover, these particles are continuously discharged together with the waste liquid.

During operation, it was confirmed that the pressure of the liquid in the cartridge between the core and the filter tube was uniform over the inner surface of the tube 8. In contrast, in prior art devices this pressure decreases from the inlet to the outlet of the cartridge.

Furthermore, the radial distance between the core and the filter tube is particularly susceptible to changes if any uneven wear of the filter tube walls occurs. However, the pressure in the tube 8 is hardly affected by such changes in radial distance. As a result, in the device of the present invention, clogging of the filter occurs isotropically over the entire surface. It is therefore possible, for example by means of a system such as 18, to apply an average counter-pressure to the membrane to very easily clean the filter.
It is clear that the use of such filter cleaning methods is much more difficult with prior art equipment. In conventional devices, the filter tubes become very unevenly clogged, so that a high counterpressure must be applied to ensure cleaning of the most heavily clogged areas of the filter.

In the device of the present invention, the pressure at the cartridge inlet and the rotational speed of the core can be adjusted independently to suit the working condition of the device in each case.
Configure seed parameters.

Furthermore, it is noteworthy that the amount of liquid that is confined at each instant (i.e., the amount of liquid contained between the core and the filter tube) is extremely small, and steady-state operating conditions are established within a very short time. That's true. Therefore, sufficient overtreatment can be carried out with a very small amount of liquid, which is advantageous when treating rare or expensive liquids.

As mentioned above, the operation of the device according to the invention is particularly stable and homogeneous, which increases its reliability compared to devices of the prior art and also reduces the time between two successive blockages of the filter due to clogging. It also increases.

Since the liquid to be treated is confined for only a very short time, the risk of deterioration of the liquid due to heat generation during overtreatment is also reduced.

As is clear from the foregoing description, the device according to the invention is particularly suitable for continuous operation with very easy adjustment of the liquid/non-liquid volume ratio. for example,
If the bacteria contained in the liquid are removed, the risk of multiplication is reduced since the bacteria are continuously expelled.

Finally, the device according to the invention is particularly simple since it does not include a circulation pump for feeding the cartridges. It should be noted that in some cases means for maintaining the liquid in the tank at a predetermined constant level without the need for the use of compressed gas to constant the pressure of the liquid at the inlet of the cartridge (e.g. means 17, 27, 26).
It is sufficient to simply install the .

The main parts of the device, namely the filter cartridge and the drive motor for the cartridge, are miniaturized. It is also possible to arrange this main part in an enclosure maintained at a constant temperature. Such an arrangement may be necessary when dealing with certain biological fluids. In this case, the heat generated by the liquid due to the operation of the device is so small that the effect of such heat on the equilibrium temperature of the liquid can be ignored.

The device of the invention can be used to extract fat or casein from milk. For example, if the pressure at the input of the cartridge is 2 bar and the average membrane pore size is 0.26 microns, the permeate flow rate is approximately 20/h/m ² of membrane. At low pressures, for example at a pressure of 50 mbar, the permeate flow rate (defined as the ratio of the total volume of non-permeate and permeate to the volume of non-permeate) is hardly influenced by the concentration ratio.
Even when the concentration rate increases from 2.5 to 5, the flow rate of permeate remains
It only changes from 9.6/hour/m ² to 9.1/hour/m ² . As the rotational speed of the core increases, the permeate flow rate increases slightly. Rotation speed from 1000 rpm to 1900
When increasing to revs/min, the permeate flow rate is 7/min.
It changes from h/m ² to 9.6/h/m ² . Of course, the provision of vanes in the core affects the flow rate of the permeate. If the core has longitudinal vanes, the flow rate increases with pressure. When the pressure increases from 0.5 to 2.5 bar, the flow rate increases from 14.5/h/ ^m2
Increases to 23.3/hour/ ^m2 .

Of course, the invention is in no way limited to the embodiments described and illustrated, which are given by way of example only. In particular, it is possible to replace some technical measures by equivalent measures without departing from the scope of the invention.

For example, hyperporous tubes can be made not only from ceramic but also from various porous materials such as fritted metal.

Furthermore, the vanes arranged on the cylindrical outer surface of the core can have any shape if desired. In particular, the vanes may be spirally arranged along the axis of the core to promote longitudinal flow of non-permeable liquid within the cartridge.

The present invention may be used generally in the sterilization of a number of liquids, and in particular in the sterilization of food grade liquids, such as milk and beer, for the purpose of sterilizing the liquid by removing bacteria.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a specific example of the device of the present invention;
2 is a longitudinal cross-sectional view of a filter cartridge forming a part of the apparatus of FIG. 1, and FIG. 3 is a cross-sectional view of the cartridge of FIG. 2, enlarged from FIG. 1...liquid, 2...tank, 3...pressure reducing valve, 4
... Gas cylinder, 5 ... Pipe, 6 ... Filter cartridge, 7 ... Casing, 8 ... Filter, 9, 10 ... End bearing member, 11 ... Core,
12...Spindle, 13...Pulley, 14...
Belt, 15...Pulley, 16...Motor, 17
...flow measuring device, 18 ... backflow system, 1
9,20,21...pipe, 22...displacement pump, 23,24...pipe, 25...auxiliary tank, 26...pump, 27...control system, 2
8...Tube, 31, 32...Terminal insertion member, 37...
... Core, 48 ... Inlet pipe, 49 ... Outlet pipe.

Claims (1)

[Scope of Claims] 1. A porous tubular filter into which the liquid to be passed is introduced, the porous tubular filter being closed at both ends to form a chamber with openings that allow the part of the liquid that has not passed through the filter to flow out. a tubular filter, a substantially cylindrical core rotatably mounted within the chamber, a cylindrical casing disposed around the filter for collecting liquid and having an outlet, and connected to the outlet. a positive displacement pump having an inlet connected to the aperture; and a control system capable of adjusting the flow rate of the positive displacement pump in accordance with the liquid flow rate measured by the flow measurement device. Liquid filtration device with. 2. A tank containing the liquid to be filtered, and a porous tubular filter connected to said tank via a pipe, the ends of which form a chamber with openings through which the portion of the liquid that has not passed through the filter can flow out. a closed porous tubular filter; a means for maintaining the liquid at a constant pressure at the inlet of the chamber; and a substance rotatably mounted coaxially within the chamber and coupled to a motor for rotational drive. a cylindrical core with a cylindrical core, a cylindrical casing with an outlet located around the filter to collect liquid, and a counter-pressure of liquid on the cylindrical outer surface of the filter to unclog the filter. controllable means for causing the liquid to flow backwards by producing a liquid, further comprising: a flow rate measuring device connected to the outlet; and a positive displacement pump having an inlet connected to the aperture. A control system capable of adjusting the flow rate of a positive displacement pump according to the liquid flow rate measured by the flow rate measuring device. 3 comprising an auxiliary tank filled with said liquid and connected to said tank via a supply pump, said control system further controlling the flow rate of said liquid as measured by said flow rate measuring device; 3. A device according to claim 2, wherein the flow rate of the feed pump can be adjusted accordingly. 4. The device according to claim 2, wherein the means for maintaining the liquid under constant pressure is means for maintaining the liquid in the tank at a constant level. 5. Apparatus according to claim 2, wherein the means for maintaining the liquid under constant pressure comprises a source of compressed gas communicating with the gas containing space in the upper part of the tank. 6 Claim 2 in which the filter has a macroporous outer tube portion and a microporous inner tube portion
Equipment described in Section. 7. The apparatus of claim 2, further comprising an enclosure surrounding the chamber, the enclosure being maintained at a constant temperature. 8. The device according to any one of claims 2 to 6, wherein the filter is made of ceramic. 9. A device according to any one of claims 2 to 6, wherein the filter is made of fritted metal.