JP2004230343A - Differential pressure continuous filtering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a differential pressure continuous filtering device requiring no large driving pressure for filtering separation (membrane separation) and from which a filtered cake can be easily taken out. <P>SOLUTION: This differential pressure continuous filtering device comprises a filtering tube 12 disposed in a longitudinal direction and a dynamic filtering means 14 disposed within the filtering tube (filtering vessel). The dynamic filtering means 14 has a plurality of dynamic filtering elements (filtering module) 16. The dynamic filtering element 16 comprises a hollow longitudinal rotation shaft 18 and a plurality of filtering plates 20, and the filtering plates 20 are attached on the hollow longitudinal rotation shaft 18 parallelly in the vertical direction with a specified interval by crossing the plates 20 with the axis of the rotation shaft 18 to allow the filtrate to flow in the plates. The dynamic filtering elements 16 are disposed in such a relation with each other that the plates 20 are meshed with each other. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
【Technical field】
TECHNICAL FIELD The present invention relates to a differential pressure continuous filtration device provided with a filter tube and dynamic filtration means provided in the filter tube (filter container: storage tank). Particularly, the present invention relates to a differential pressure continuous filtration device suitable for performing continuous treatment of factory wastewater.
[0002]
[Background Art]
Membrane separation has attracted attention as a method of treating various industrial wastewaters, but has the disadvantage that the filtration rate is reduced by cakes deposited on the filtration surface (filter media surface or membrane surface). As a membrane separation method for compensating for this disadvantage, there is a filtration method in which a high shear force is applied to a filtration surface to peel off the deposited cake. This method is called dynamic filtration.
[0003]
Conventionally, dynamic circulation type dynamic filtration is widely used (see FIG. 1).
[0004]
In this method, as shown in the drawing, a pressure is applied to the raw water, and a shear force is applied by passing the raw water at a high speed (1 to 3 m / s) to continue the filtration. Since the amount of filtered water cannot be obtained only by passing the raw water once, the raw water is repeatedly applied with pressure and supplied at high speed to the surface of the filter medium. For this reason, a large power source is required for the obtained filtered water.
[0005]
For this reason, the following structure (structure) is introduced in Patent Document 1 and the like as a membrane separation means (dynamic filtration means) (see Claims, page 3, two pillars, second stage, etc.).
[0006]
"In a cylindrical case having an inlet and an outlet for a liquid to be treated, a membrane module having a number of disk membranes mounted in parallel on a hollow vertical rotation shaft is housed, and the permeate from the disk membrane is transferred to the hollow vertical axis. A structure that discharges out of the device through the hollow part of the rotating shaft. "
Further, a configuration in which a cross section of a case is made elliptical and two membrane modules are housed in the case so that disk membranes are alternately meshed with each other is introduced as a modification (the second lower stage in the same).
[0007]
In the case of this configuration, "by rotating each membrane module in the same direction, the agitation of the liquid to be treated is promoted in the region where the disk films intersect, and the disk film and the liquid to be processed come into good contact with each other.""The solids adhered to the film surface of the disc film are easily peeled off in this region, so that the film surface can always be maintained in the properties. Therefore, the frequency of the washing step can be reduced." is there.
[0008]
However, in the case of the differential pressure filtration device having the above configuration, the case (filter tube) is placed horizontally, which requires a large driving pressure for filtration (membrane separation) and also requires a high degree of sealing. . Furthermore, taking out the filter cake was troublesome.
[0009]
[Patent Document 1]
Japanese Patent Publication No. 6-98275
DISCLOSURE OF THE INVENTION
In view of the above, an object of the present invention is to provide a continuous-pressure differential filtration device that does not require a large driving pressure for filtration separation (membrane separation) and that can easily take out a filter cake.
[0011]
Means for Solving the Problems The present inventors have diligently made efforts for development in order to solve the above-mentioned problems, and as a result, have arrived at a differential pressure continuous filtration device having the following configuration.
[0012]
A pressurized continuous filtration device comprising: a filter tube provided in a vertical direction; and dynamic filtration means provided in the filter tube (filter container: storage tank).
The dynamic filtration means includes a plurality of dynamic filtration elements (filtration modules),
The dynamic filtration element includes a hollow vertical rotation shaft and a plurality of filter plates, and the filter plates are vertically intersected at predetermined intervals by intersecting the axis of the hollow vertical rotation shaft so that a filtrate can flow thereinto. It is a configuration that can be installed in parallel,
The dynamic filtration elements are characterized in that they are arranged such that their filtration plates are in mesh with each other.
[0013]
Since the filter tube is disposed in the vertical direction and a plurality of filter plates are vertically arranged in parallel with the filter tube via the hollow vertical rotation shaft, the filter column is particularly pressed against the water column pressure (particularly, the lower filter plate). In addition, as compared with the case where the filter cylinder is a horizontal type and the filter plates are arranged in parallel in the horizontal direction, less power is required for generating a driving pressure required for filtration (membrane separation). Further, as a result, the upper seal is a gas-compatible seal and has a low sealing pressure, so that the seal structure is simpler than that of the liquid-compatible seal. Also, the filter cake peeled off from the filter plate can be easily taken out from the bottom wall of the filter tube by utilizing gravity. Further, since the filtration modules are arranged in a state where the filtration plates are in mesh with each other, the shearing action of the filtration plates promotes the stirring of the liquid to be treated in the shear zone, and the cake adhered to the filtration plates. Is promoted. Therefore, it becomes possible to increase the filtration efficiency of the liquid to be treated by stirring and to increase the continuous filtration time by washing the filter plate.
[0014]
In the above-described configuration, it is preferable that the hollow vertical rotation shaft be supported by the filter cylinder ceiling wall as a free end at the lower end, and that a mechanism be provided to remove a filtrate from above the hollow vertical rotation shaft by differential pressure. Since the hollow vertical rotating shaft has a free end at the lower end, the rotating shaft seal at the lower end is not required. That is, only the seal against gas (air) is required, and the cake-containing liquid can be easily removed from the bottom wall. Become.
[0015]
In each of the above-described configurations, it is desirable that at least the lowermost filter plate includes a lower surface baffle plate and / or that a side surface baffle plate is provided on a peripheral surface of the filter plate. By the action of the lower surface baffle and / or the side baffle, the dispersed particles of the liquid to be treated (filtration solution or raw water) can be made uniform, and the cake-forming particles (dispersion particles) that settle out are evenly dispersed. Therefore, an increase in filtration efficiency can be expected.
[0016]
Further, in each of the above configurations, the filter plate includes a filtration layer and a porous core layer disposed inside the filtration layer, and the porous core layer has a pore size larger than the pore size of the filtration layer. It is desirable to be formed with a rigid open-celled porous material having the same. The material for forming the filtration layer may not have rigidity, and the selection range of the material for forming the filtration layer is increased. In addition, the filter layer can be used as thin as possible, and since the pore diameter of the inner rigid open-cell porous body is larger than the pore size of the filter layer, the filter layer can be made as thin as possible. The pressure loss of the liquid permeated through the filtration layer can be reduced. Therefore, a small filtration driving pressure is required, which results in energy saving.
[0017]
In addition, it is desirable that the dynamic filtration element be rotated synchronously in the same direction as the filtration method in the case of performing the differential pressure continuous filtration by operating the differential pressure continuous filtration device of each of the above configurations.
A shear zone (the mesh portion of the filter plate) in which the traveling directions of the filter plates are opposite to each other is generated, and the shearing action promotes cake peeling and promotes agitation of the treatment. As a result, the cleaning effect and the filtration efficiency are improved.
[0018]
When operating the above-mentioned filtration device, it is desirable to variably control the number of revolutions of the dynamic filtration element according to the properties of the liquid to be treated (treated water). This is for optimization of operation efficiency.
[0019]
The concept of the differential pressure continuous filtration device of the present invention is schematically described in comparison with a conventional flow-through circulation type dynamic filtration device as follows.
[0020]
A disk-shaped filter medium is vertically stacked on one shaft. Further, they are alternately combined and rotated at a high speed in the same direction. The disk fixed to one axis has the opposite direction of the disk in the part combined with the other axis, so it is possible to apply a high shear field to the surface of each disk filtration material Become. Further, the liquid to be treated (raw water) is vibrated to promote the peeling of the cake deposited on the surface of the disk-shaped filter medium as the filtrate is concentrated. According to this method, the circulation of the raw water is not necessary, and the effect of cake separation can be expected at a low rotation speed even for a disk rotation.
[0021]
Further, according to this concept, it is possible to easily change the shearing force by changing the number of rotations of the disk. For this reason, it is also possible to control the intentional attachment of the cake made of the solid content to be collected to the surface of the filter medium, so that it is possible to form a dynamic layer even with fine particles on the order of submicrons. For this reason, when collecting fine particles, a coarse filter material (filter material) as used in general filtration can be used, and solid-liquid separation without adding a chemical (aggregating agent) becomes possible. In the case of separating fine particles by a conventional method (liquid circulation type), the applicable range of this operation is limited.
[0022]
Furthermore, the shear field formed by the rotating disk filter medium has different peripheral speeds, so the center of the disk is small and the outer periphery is large. Conversely, the outer peripheral portion having a high peripheral speed is located at the center of the disc filtration material, so that the uniformity of the shearing force can be measured. Thereby, a uniform shear field can be formed in the filter medium, and stable filtration can be continued.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. FIG. 2 is a schematic model sectional view of the present embodiment, FIG. 3 is an enlarged half sectional view showing an example of a filter plate, and FIG. 4 is an explanatory plan view showing a meshing state of the filter plate of FIG. is there.
[0024]
Basically, it is a continuous differential pressure filtration device provided with a filter tube (reservoir) 12 disposed in the vertical direction and a dynamic filtration means 14 disposed in the filter tube 12. The means (filtration module) 14 comprises a plurality of dynamic filtration elements 16.
[0025]
The dynamic filtration element 16 includes a hollow vertical rotation shaft 18 and a plurality of filter plates 20, and the filter plate 20 intersects the axis of the hollow vertical rotation shaft 18 so that a filtrate can flow therethrough. The dynamic filtration elements 16 are arranged so as to be in parallel with each other in an up-down direction at intervals, and the filter plates 20, 20 are in mesh with each other.
[0026]
In the present embodiment, the filter tube 12 and the hollow vertical rotation shaft 18 are arranged in the vertical direction, but may be both inclined directions (inclination angle of 45 ° or more). In this example, the number is two, but may be three or more. In addition, the filter tube 12 has a horizontal cross section and a flat oval shape, but is not limited thereto. That is, the horizontal cross section of the filter cylinder 12 does not have to be an elliptical shape as shown in FIG. 4 along the outer peripheral shape of the filter plate 20, and may be a rectangular cross section.
[0027]
The filter plate 20 has a disk shape as shown in the figure, but may have an elliptical shape or a polygonal shape (triangle, square, octagon). Further, the attachment direction of the filter plate 20 is usually horizontal, but may be an oblique direction (inclination angle of 45 ° or less). In this case, the uppermost filter plate 20 is in a partially submerged form. However, when the bent portion on the water surface is submerged, it receives a shearing force by water, and can expect a cake peeling (cleaning) action.
[0028]
In the present embodiment, the hollow vertical rotation shaft 18 is supported by the ceiling wall of the filter tube 12 as a free end at the lower end, and a mechanism is provided for extracting a filtrate from above the hollow vertical rotation shaft 18 by differential pressure. .
[0029]
Specifically, the pair of hollow vertical rotation shafts 18 are supported by a pair of thrust bearings 22 attached to the ceiling wall of the filter tube 12. Here, although not shown, a seal member such as an O-ring is usually provided below the thrust bearing 22.
[0030]
A driven pulley 24 is attached to the upper end of the hollow vertical rotation shaft 18, and is synchronized in the same direction by a timing belt 26 by a drive pulley 30 attached to an output shaft 28 a of a motor (motor) 28 in the same direction. It is rotatable. The driving means of each hollow rotary shaft 18 may be a separate driving means using a different motor or the like.
[0031]
Further, a raw water supply pipe 36 having a raw water supply pump 34 is connected to the filter tube 12 so that raw water (liquid to be treated) can be supplied from a raw water tank 32. At this time, a liquid level gauge 13 is attached to the ceiling wall of the filter tube 12 so that the supply amount of raw water can be controlled.
[0032]
In addition, in order to obtain a filtration drive pressure (separation drive pressure), a pressurized gas (air) supply pipe 40 provided with a compressor 38 at a source side for supplying pressurized air (pressurized gas) into the filter tube 12 is provided. It is connected. The pressurized gas is not necessarily air, but may be an inert gas such as nitrogen depending on the case where the liquid to be treated refuses to oxidize.
[0033]
On the other hand, a concentrated liquid discharge port 44 provided with a valve (ball cock) 42 is disposed at the bottom of the filter tube 12 in order to collect the concentrated liquid (cake-containing liquid).
[0034]
Further, a filtrate recovery pipe 45 is connected to the upper end of each hollow vertical rotation shaft 18. In addition, a vacuum suction means (for example, a compressor) may be provided on the filtrate collection pipe side together with or instead of the pressurizing means (compressor 38) for obtaining the filtration drive pressure. Good.
[0035]
The filter plate 20 has a configuration in which at least the lowermost filter plate 20 includes a lower surface baffle plate 46 (or 46A) and / or a configuration in which a side surface baffle plate 48 is provided on the peripheral surface of the filter plate 20. It can be. This is because the stirring efficiency of the liquid to be treated is promoted to increase the filtration efficiency (see FIG. 3).
[0036]
The shape of each of the baffles 46 and 48 is not limited to a semicircular shape as shown in FIG. 3, but may be any shape such as a turbine shape (for example, a rectangular shape) or a twist shape frequently used for a stirring blade. For example, as shown by a two-dot chain line in FIG.
[0037]
As shown in FIG. 3, the filter plate 20 includes a filter layer 20a and a porous core layer 20b disposed inside the filter layer 20a. The porous core layer 20b is formed of the filter layer 20a. It is desirable to use a rigid open-cell porous body having a larger pore diameter than the pore diameter. Here, the filter layer 20a and the filter plate 20 are usually detachable. This is because the filtration layer 20a is easily damaged, and it is necessary to use a filter having a different pore size depending on the filtrate.
[0038]
The filtration layer 20a usually has a pore size on the order of several microns, and the porous core material layer (rigid open-celled porous material) 20b usually has a pore size on the order of several hundred microns. Here, as a material for forming the filtration layer 20a, a porous ceramic, plastic, sintered metal, or the like may be used. However, in the present embodiment, since the inside is formed of a rigid open-celled porous body, woven fabric, nonwoven fabric, paper It is also possible to use a flexible material such as a plastic or a porous plastic film. On the other hand, as a material for forming the porous core layer 20b, a material having a large hole diameter among the above-mentioned ceramics, plastics, sintered metals and the like can be used, but the support structure may be formed by a wire mesh or a punching metal. In addition, the thickness of the filtration layer depends on the required filtration performance, filtration medium, and the like, but is usually 0.5 to 5 mm in the case of a ceramic filter, for example.
[0039]
Next, an operation method of the differential pressure filtration device will be described.
The supply pump 34 is operated to supply the liquid to be treated from the raw water tank 32 through the raw water supply pipe 36 to a predetermined amount while being controlled by the level gauge 13, and the compressor 38 is operated to increase the pressure. Air is supplied into the filter tube 12 to pressurize the inside of the filter tube 12 (normally 0.05 Mpa or more).
[0040]
Next, the motor 28 is operated to rotate the vertical hollow vertical rotation shaft 18. The rotation speed at this time is usually ⁰ to 1000 min ^-1 , preferably 100 to 1000 min ^-1 .
[0041]
Then, since the filtrate is in a pressurized state (not less than the driving pressure for filtration) by the pressurized air, it is filtered through the filter layer 20a of the filter plate 20, and the filtrate is a porous core material layer (rigid open cell porous body). The fluid flows into the hollow vertical rotation shaft 18 through a filtrate flow hole 19 formed in the outer peripheral wall 18a of the hollow vertical rotation shaft 18 and the hollow vertical rotation shaft 18, and is collected as a filtrate through a filtrate recovery pipe 45.
[0042]
At this time, since the vertical hollow vertical rotation shaft 18 is rotating, the liquid to be treated (filtration solution: raw water) is stirred and mixed, and the dispersed particles (residual particles: cake-forming particles) in the liquid to be treated are uniformly dispersed. Therefore, the filtration efficiency is improved. In addition, in a portion where the filter plates 20 mesh with each other, the rotation direction is reversed, a shear zone S (a hatched portion in FIG. 4) is generated, and the filter cake is not easily deposited on the filter surface. Therefore, good filtration efficiency can be maintained for a long time. Nevertheless, if filter cake accumulates on the filtration surface, it is desirable to intermittently reverse the filtration element. This intermittent reverse rotation of the filter element not only increases the shearing action in the shearing zone immediately after the reversal, but also causes a shearing action on the filtering surface other than at the meshing portion, and causes cake separation from the filtering surface ( Washing) is promoted. That is, the cleanability of the filtration surface further increases. Here, the term “intermittently” includes not only the case where the rotation is temporarily reversed, but also the case where the normal rotation operation time and the reverse rotation operation time are substantially the same time.
[0043]
Then, when the concentration of the liquid containing the filter cake increases (that is, when the concentration of the liquid to be treated reaches a predetermined level or more), the on-off valve at the bottom is opened and the concentrated liquid is collected from the concentrated liquid collecting pipe.
[0044]
[Test example]
The 10% O / W emulsion was filtered at a filtration drive pressure of 0.2 MPa using the continuous differential pressure filtration device shown in FIG. 2, and the results are shown in FIG.
[0045]
The dimensional specifications of the used filtering device are as follows.
[0046]
Inside the filter tube 12 (major axis: 420 mm, minor axis: 300 mm, height: 300 mm)
Filter plate (200 mmφ × 8 mmt, surface layer pore diameter 0.10 μm made of ceramic), filter plate 20 pitch (20 mm)
Hollow shaft (outer diameter 20mmφ x inner diameter 10mmφ), distance between hollow shafts (120mm)
Here, v is the accumulated filtration amount per unit filtration area (cm), and θ is the elapsed time, so dθ / dv is the reciprocal of the filtration speed.
In other words, the filtration speed decreases steadily in the case of dead end filtration (when the disk is not rotated) rising to the right, whereas the rotation of the disk stabilizes the filtration speed. The filtration speed was higher as the rotation speed of the filter plate 20 (disc) was higher, but almost no difference in the filtration speed was observed between 500 rpm and 1000 rpm.
[0047]
[Industrial applicability]
Examples of applications of the continuous pressure differential filtration device of the present invention include the following.
[0048]
{Circle around (1)} Recycling of factory wastewater Primary treatment equipment It is very effective that inorganic salts can be filtered without adding chemicals. Examples of the factory wastewater include various washing wastewater, CMP (Chemical Mechanical Polishing) wastewater, and various emulsion-based wastewater.
[0049]
{Circle over (2)} An apparatus for recovering impurities from liquid industrial chemicals, which can be used for circulating, for example, oily, water-soluble cutting fluids, grinding fluids and the like.
[0050]
(3) Useful substance recovery device It can be introduced as a solid-liquid separation device in each step of the factory, and is extremely effective for the recovery of useful solids because no chemicals are added.
[0051]
(4) Concentration of organic and inorganic materials as solids in the liquid in the production process of the concentration device can reduce the drying cost of the next process [Brief description of the drawings]
FIG. 1 is a schematic view of a flow-through circulation type dynamic filtration.
FIG. 2 is a schematic model sectional view of the present embodiment.
FIG. 3 is an enlarged half sectional view showing an example of a filter plate.
FIG. 4 is an explanatory sectional view for a plane showing a meshing state of the filter plates of FIG. 2;
FIG. 5 is a graph showing test results of the filtration device of the present invention.
[Explanation of symbols]
12 Filter tube (storage tank)
14 Dynamic filtration means 16 Dynamic filtration element 18 Hollow longitudinal rotation shaft 20 Filter plate 20a Filter layer 20b Porous core layer 38 Compressor (differential pressure generation means)
46 Lower surface baffle plate 48 Side baffle plate S Shear zone (intermeshing portion of filter plates)

Claims (7)

A pressurized continuous filtration device comprising a filter tube disposed in a vertical direction and dynamic filtration means disposed in the filter tube (filter container),
The dynamic filtration means includes a plurality of dynamic filtration elements (filtration modules),
The dynamic filtration element includes a hollow vertical rotation shaft, and a plurality of filter plates, and the filter plate intersects the axis of the hollow vertical rotation shaft so that a filtrate can flow in the vertical direction at a predetermined interval. It is a configuration that can be attached in parallel to
The continuous differential pressure filtration device, wherein the dynamic filtration elements are arranged such that the filtration plates are in mesh with each other. The hollow vertical rotation shaft is supported as a lower end free end by a filter cylinder ceiling wall, and a mechanism is provided for extracting a filtrate from above the hollow vertical rotation shaft by a differential pressure. The differential pressure continuous filtration device as described in the above. 3. The continuous differential pressure filtration device according to claim 1, wherein the at least the lowermost filtration plate includes a lower surface baffle plate. The differential pressure continuous filtration device according to claim 1, wherein a side wall baffle is provided on a peripheral surface of the filter plate. The filter plate includes a filtration layer and a porous core layer disposed inside the filtration layer, wherein the porous core layer has a rigid open-cell structure having a pore size larger than a pore size of the filtration layer. 2. The continuous differential pressure filtration device according to claim 1, wherein the filtration device is formed of a body. A method for performing continuous differential pressure filtration by operating the continuous differential pressure filtration device according to any one of claims 1 to 5, wherein the plurality of dynamic filtration elements are synchronously rotated in the same direction. Differential pressure continuous filtration method. The method according to claim 6, wherein the number of rotations of the dynamic filtration element is variably controlled in accordance with the property of the treated water.

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