JP2009082860A - Filtration apparatus and filtration method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filtration apparatus capable of easily maintaining a high dehydration performance. <P>SOLUTION: The filtration apparatus includes a back pressure control means for adjusting the opening area of a discharge port 24 at a predetermined set area so that a back pressure in a filtration space 4 may become a predetermined set pressure in a filtration operation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a filtration device and a filtration method.

Filter materials such as metal screens, nets, and perforated plates are superior in terms of operability, maintainability, durability, etc. compared to cloth (fiber) materials. There is a pressure filtration device such as a rotary pressure dehydrator. This device has a long history and has a very simple structure. It is characterized by low power, low noise, low cost, etc., and is excellent when applied to a solid-liquid mixture with low solid content and low dehydration. In addition, it is widely used in the sewage sludge dehydration field. (For example, see Patent Documents 1 and 2)
However, in a screw press composed of a cylindrical outer filter medium and a screw inserted therein, the slurry to be treated is transferred at a low speed from the inlet side to the outlet side, and at the same time, generated by the tightening force of the screw. Although it is continuously dehydrated by the pressing pressure, since the filtrate is squeezed out only from the outer filter medium, it is difficult to shorten the length of the outer filter medium, and it is difficult to downsize the equipment.
On the other hand, in a rotary pressurization type dehydrator, it is necessary to increase the diameter of the disk or to install a plurality of dehydrators in order to improve the throughput of dehydration filtration. It was.
Therefore, in view of such problems, the present inventors provide a concentrically disposed cylindrical or conical inner filter medium and outer filter medium, and a filtration space between these inner filter medium and outer filter medium. A spiral partition, the slurry to be treated is fed from one end of the filtration space, the cake is discharged from the other end of the filtration space, and the filtrate passes through the inner and outer filter media. Is a filter device configured to discharge the outside of the filter, and the filter device is configured such that the inner filter medium and / or the outer filter medium rotate around the axis and the spiral partition does not rotate (for example, Patent Document 3). 4).
In this filtration device, higher dehydration performance can be exhibited by appropriately applying a back pressure and exhibiting a sufficient squeezing effect. For this reason, providing the mechanism which adjusts the cross-sectional area of a cake discharge flow path is also proposed (refer patent document 4).
JP 2001-212697 A JP 2001-113109 A JP 2006-346600 A JP 2007-160246 A

However, simply adjusting the cross-sectional area of the cake discharge channel requires readjustment when the cross-sectional area is changed due to maintenance or failure, etc., and it is troublesome to maintain high dewatering performance. was there.
Therefore, a main problem of the present invention is to make it possible to easily maintain high dewatering performance.

The present invention that has solved the above problems is as follows.
<Invention of Claim 1>
A concentric arrangement of cylindrical or conical inner and outer filter media;
A spiral partition provided in a filtration space between the inner filter medium and the outer filter medium, and extending in a direction along the center of the inner filter medium while turning around the inner filter medium;
A rotational drive source that rotates the inner filter medium and / or the outer filter medium around its center,
The spiral partition is configured not to rotate,
The slurry to be treated is fed from one end side of the filtration space, the filtrate that has passed through the inner filter medium and the outer filter medium is discharged to the outside, and the cake formed by this filtration is transferred along the partition A filtration device configured to be discharged to the other end side of the filtration space,
While having an outlet for discharging the cake from the filtration space, an opening adjusting means for adjusting the opening area of the outlet,
Back pressure control means for adjusting the opening area of the discharge port by the opening adjusting means so that the back pressure of the filtration space becomes a predetermined set pressure during the filtration operation;
A filtration device comprising:

(Function and effect)
In the present invention, even when the opening area is changed due to maintenance or failure, the opening adjustment is performed so that the back pressure of the filtration space becomes the predetermined set pressure by the back pressure control means during the filtration operation. Since the opening area of the discharge port can be adjusted by the means, high dewatering performance can be easily maintained.

<Invention of Claim 2>
The said back pressure control means adjusts the opening area of the said discharge port to the area set beforehand based on the correlation with the back pressure of the said filtration space, and the opening area of the said discharge port. Filtration equipment.

(Function and effect)
The correlation between the back pressure and the opening area of the discharge port varies depending on the dewatering properties of the cake. Therefore, the opening area of the discharge port that becomes the set back pressure by the test is obtained in advance, and the control means is configured to adjust the opening area of the discharge port during the filtration operation with this as the set area. A simple device configuration is preferable because a sufficient effect is exhibited.

<Invention of Claim 3>
The back pressure control means includes a pressure gauge for measuring the back pressure of the filtration space, and the back pressure control means is configured to release the release pressure by the opening adjustment means so that a measured value by the pressure gauge becomes the set pressure during filtration operation. The filtration apparatus of Claim 1 or 2 which adjusts the opening area of an exit.

(Function and effect)
Since the dewatering property of the cake fluctuates during the filtration operation, the opening area of the discharge port that becomes the set back pressure (the correlation between the back pressure and the opening area of the discharge port varies depending on the dehydration property of the cake as described above) also fluctuates. . Therefore, as described in this section, it is preferable to feedback control the opening area of the discharge port by measuring the back pressure.

<Invention of Claim 4>
As the opening adjusting means, there are provided an opening adjusting body which is movable along a surface having the discharge port so that an area of a portion overlapping with the discharge port is changed, and a position detecting unit of the opening adjuster. And
The back pressure control means moves the opening adjusting body according to the position detection result by the position detecting means, and changes the area of the portion overlapping the opening adjusting body and the discharge opening, thereby opening the discharge opening. To adjust the area,
The filtration apparatus of any one of Claims 1-3.

(Function and effect)
It is preferable to configure the opening adjusting means and the back pressure control means in this way because sufficient back pressure control can be performed with a simple configuration.

<Invention of Claim 5>
A concentric arrangement of cylindrical or conical inner and outer filter media;
A spiral partition provided in a filtration space between the inner filter medium and the outer filter medium, and extending in a direction along the center of the inner filter medium while turning around the inner filter medium;
A rotational drive source that rotates the inner filter medium and / or the outer filter medium around its center,
The spiral partition is configured not to rotate, using a filtration device,
The slurry to be treated is fed from one end side of the filtration space, the filtrate that has passed through the inner filter medium and the outer filter medium is discharged to the outside, and the cake formed by this filtration is transferred along the partition Letting it be discharged to the other end side of the filtration space,
While providing a discharge port for discharging the cake from the filtration space, providing an opening adjusting means for adjusting the opening area of the discharge port,
During filtration operation, the opening area of the discharge port is adjusted by the opening adjusting means so that the back pressure of the filtration space becomes a predetermined set pressure.
The filtration method characterized by the above-mentioned.

(Function and effect)
The same effect as that of the first aspect of the invention can be achieved.

  As described above, according to the present invention, advantages such as high dehydration performance can be easily maintained.

  FIGS. 1-5 has shown the example of a filtration apparatus, and this filtration apparatus is arrange | positioned so that the center may follow the up-down direction, and the inner side filter medium 1 and the outer side filter medium 2 which make a cylindrical shape, respectively, A spiral partition 3 provided in a filtration space between the inner filter medium 1 and the outer filter medium 2 and extending so as to turn around the inner filter medium 1 is provided.

  As a filter medium used for the inner and outer filter media 1 and 2, a filter cloth can be used in addition to a screen of punching metal, wedge wire, wire mesh or the like. In addition, a wedge wire with a high opening ratio of the filtration surface at the lower part of the filtration space 4 where solid-liquid separation is main, and a contact area with the cake is high at the upper part of the filtration space 4 where compression dehydration is main (low opening ratio). A punching metal may be arranged.

  As shown in FIG. 1 and FIG. 5, the partition 3 has a spiral shape (a spiral shape or a ribbon screw shape) extending so as to rise while turning around the inner filter material 1. A plurality of strips (two strips in the illustrated example) are provided in the cylindrical filtration space 4 formed between the outer filter medium 1 and the outer filter medium 2 with a uniform rotational angle difference in the circumferential direction. The inner peripheral edge and the outer peripheral edge of the partition 3 are close to or in contact with the filtration surfaces of the inner filter medium 1 and the outer filter medium 2, respectively. If the partition 3 is provided in a multi-row spiral shape, the height of the discharge cake can be suppressed, the required height of the discharge path can be reduced, and the overall height of the apparatus can be kept low. The advantage that it improves is brought about. In addition, it is preferable to design so that the ratio of the pitch of the partition 3 and the radial direction space | interval of the inner side filter medium 1 and the outer side filter medium 2 may be set to 1-5.

  Hereinafter, in more detail, the present apparatus example includes a horizontal main support base 40 and a horizontal sub-support base 41 supported by the main support base 40 that is spaced above the main support base. Have. The outer filter medium 2 is rotatably supported by the main support base 40. Specifically, a cylindrical support portion 2X is connected to the upper end of the outer filter medium 2, and an annular rotating plate 20 (the upper surface forms an annular rotation surface) concentric with the outer filter medium 2 on the upper surface of the support portion 2X. The inner peripheral edge of the first rotary pinion gear 21 is connected to the lower surface of the annular rotary plate 20 on the outer side in the radial direction, concentrically with the outer filter medium 2, and the first annular pinion gear 21 is The outer filter medium 2 provided on the main support 40 is supported by the annular rail 22 concentric with the outer filter medium 2. The teeth on the outer peripheral surface of the first annular pinion gear 21 are meshed with the pinion gear G1 of the drive shaft of the first motor (gear motor) M1 mounted on the main support 40.

  The lower end portion of the inner filter medium 1 is connected and integrated with the lower end portion of the outer filter medium 2 via an annular plate 6 that closes the lower opening between the inner and outer filter mediums 1 and 2 (filtration space) below the lower end of the partition 3. Has been. Therefore, by driving the first motor M1 with a speed reducer, not only the outer filter medium 2, but also the inner filter medium 1 connected thereto is integrally rotated. Further, above the lower connection position (annular plate 6) of the inner and outer filter media 1, 2, the two filter media 1, 2 are not connected, and the upper portion between the two filter media 1, 2 (filter space 4) is annular. The partition 3 protrudes above the upper end of the outer filter medium 2 through the annular opening. An annular support portion 3X is added to the upper end of the partition 3, and the upper end of the support portion 3X is suspended and supported on the upper portion of the apparatus by being connected and fixed to the sub-support base 41, and the lower end of the partition 3 is filtered. It is located near the lower end of the space 4. The inner filter medium 1 also projects upward from the upper end of the outer filter medium 2, and the upper end of the inner filter medium 1 is pivotally supported by the sub-support base 41. By integrating the structure, supporting the cantilever, and sharing the drive in this way, the maintenance is excellent, the number of parts is small, and the assembly is easy.

  A lower casing 42 is suspended and supported on the lower side of the main support 40 so as to surround and surround the outer filter medium 2 with a gap corresponding to the filtrate discharge space 16. The lower casing 42 only forms the filtrate discharge space 16, and a large load is not applied.

  A filtrate outlet 13 is provided at the bottom of the lower casing 42. In addition, the slurry supply pipe 10 passes from the outside of the lower casing 42 through the bottom of the lower casing 42 to the lower ends of the inner and outer filter media 1 and 2 at the center of the inner and outer filter media 1 and 2. After extending along the radial direction, the tip extends through the inner filter medium 1 and opens into the filtration space 4 above the annular plate 6. A swivel joint 45 is interposed in the feed pipe 10 outside the lower casing 42 and can be rotated with the rotation of the inner and outer filter media 1 and 2 while maintaining the communication state inside the pipe. ing. The slurry to be treated is pressure-fed and supplied by a pump (not shown) through the inlet pipe 10. In addition, although the inlet conduit 10 passes through the inner filter medium 1, the inner filter medium 1 is open downward, so that the inner filter medium 1 and the outer filter medium 2 communicate with the common filtrate discharge space 16. ing. Therefore, the filtrate discharge path is compact and simple.

  On the upper side of the filtration space 4 (equal to the upper side of the outer filter medium 2), there is provided a cylindrical discharge space 4X formed by continuously extending the filtration space 4 as it is. The upper part of the discharge space 4X is surrounded by the bottom surface of the support part 3X of the partition 3, and the inner periphery is surrounded by the outer periphery of the inner filter medium 1. Each partition 3 extends to the upper end of the discharge space 4X, and a terminal wall 3E is erected on the upper surface of the lower end portion of the portion from the lower end to the upper end of each extended portion. The outer peripheral surface up to the upper end is covered with a peripheral wall 3R that covers the same height range as the end wall 3E, and an opening between the peripheral walls 3R serves as a discharge port 24 that opens to the outer peripheral surface (side surface) of the discharge space 4X. The number of the partitions 3 is formed. The end wall 3 </ b> E has a function of receiving the cake rising along the partition 3 and pushing it out to the discharge port 24.

  The outer periphery of the discharge space 4X is concentrically surrounded by a cylindrical opening adjusting body 26. An opening 26 </ b> X is formed in the opening adjusting body 26 at a position overlapping the discharge port 24, and an annular top plate 26 </ b> P is projected so as to cover the upper part of the annular rotating plate 20. The opening adjusting body 26 is rotatable in the circumferential direction of the discharge space 4 </ b> X, and is connected to the second annular pinion gear 27 concentrically at the upper end surface thereof, and the teeth on the outer peripheral surface of the second annular pinion gear 27. Is meshed with the pinion gear G2 of the drive shaft of the second motor M2 with a reduction gear mounted on the sub support base 41. By moving the opening adjusting body 26 by the drive control of the second motor with speed reducer M2, the area of the portion overlapping the non-opening portion other than the opening portion 26X and the discharge port 24 is changed, and the opening of the discharge port 24 is changed. The area (the portion overlapping the opening 26X) is adjusted.

  A non-contact sensor 30 such as a proximity switch is provided as a position detection unit of the opening adjuster 26. In the illustrated embodiment, a detection unit (detection plate) 31 is provided at an appropriate position on the upper side of the annular top plate 26P of the aperture adjuster 26 so that the position can be adjusted, and on the movement locus of the detector 31 accompanying the movement of the aperture adjuster 26. A non-contact sensor 30 is provided, and the position of the opening adjustment body 26, that is, the opening area of the discharge port 24, based on the correspondence between the position where the detection unit 31 is detected by the non-contact sensor 30 and the position of the opening adjustment body 26. Can be detected. The non-contact sensor 30 can output a detection signal and a non-detection signal of each detection unit 31 to a back pressure control means to be described later, and the back pressure control means responds to each signal with the second motor M2 with a reduction gear. By performing the drive control, it is possible to adjust the back pressure based on the opening area of the discharge port 24. The means for adjusting the opening area of the discharge port 24 constitutes the opening adjusting means of the present invention.

  The detection unit 31 is provided at a position that is detected by the non-contact sensor 30 at least in a state where the opening area of the discharge port 24 is a predetermined set area. The set area of the discharge port 24 is an area where the back pressure of the filtration space 4 becomes a predetermined set pressure. The set pressure of the back pressure can be determined as appropriate, but the maximum value of the back pressure (however, the opening of the discharge port 24) It is preferable to set it in the vicinity thereof (except when the area is 0). Since the correlation between the back pressure and the opening area of the discharge port varies depending on the dewatering property of the cake, it is preferable to obtain these set pressure and set area in advance by a test.

  When back pressure control is performed in stages (including feedback control described later), the detection units 31 can be provided at a plurality of locations at intervals in the moving direction of the opening adjuster 26. In this case, the specific position of the detection unit 31 can be determined as appropriate according to the fineness of the back pressure control, but at least in a state where the opening area of the discharge port 24 is a predetermined set area. It is preferable to provide the detectors 31 at the basic position detected by the above-mentioned method, the adjustment position near one side, and the adjustment position near the other side. Moreover, it is preferable to provide the detection part 31 also in the position detected by the non-contact sensor 30 in the state in which the discharge port 24 is fully opened and fully closed. In addition, it can replace with the said non-contact sensor and can also detect the position of the opening adjustment body 26 using a well-known rotary encoder and a rotation angle sensor.

  On the other hand, the annular rotary plate 20 described above is provided so that the upper surface is located between the lower end of the discharge port 24 and the upper end of the outer filter medium 2 and surrounds the discharge space 4X in plan view. A discharge guide plate 25 is erected on the upper side of the annular rotary plate 20 so as to cross from the inner peripheral edge to the outer peripheral edge of the annular rotary plate 20. The lower end of the discharge guide plate 25 is slightly separated from the upper surface of the annular rotary plate 20. The inner end of the discharge guide plate 25 (the end located on the inner peripheral side of the annular rotating plate 20) is in contact with the outer side edge of the termination wall 3E in any one discharge port 24, and the outer end. Is connected to the main support 40 so as to protrude outward from the outer peripheral edge of the annular rotating plate 20. The discharge guide plate 25 crosses the annular rotating plate 20 obliquely with respect to the radial direction so as to be positioned on the rear side in the rotation direction of the annular rotating plate 20 as it goes to the outer end.

  Further, at a position located between the discharge ports 24 in the rotation direction on the upper side of the annular rotating plate 20 so as to cross from the inner peripheral edge of the annular rotating plate 20 to an intermediate position (for example, the center) between the inner peripheral edge and the outer peripheral edge. An outside guide plate 29 is erected. The lower end of the outer guide plate 29 is slightly separated from the upper surface of the annular rotating plate 20, and the inner end (the end located on the inner peripheral side of the annular rotating plate 20) is the outer peripheral surface of the opening adjusting body 26. It is connected to. Further, the outer guide plate 29 crosses the annular rotary plate 20 obliquely with respect to the radial direction so as to be positioned on the rear side in the rotational direction of the annular rotary plate 20 toward the outer end.

  The outer periphery of the annular rotary plate 20 and the annular top plate 26P is surrounded by a cylindrical upper casing 43. In the upper casing 43, a range from a circumferential position corresponding to the inner end of the discharge guide body 25 to a circumferential position corresponding to the outer end is opened as a discharge chute 44. In the illustrated embodiment, the upper casing 43 has an upper end connected to the sub-support base 41 and a lower end connected to the main support base 40, and the sub-support base 41 is supported by the sub-support base 41 via the upper casing 43. It has become.

  On the other hand, the inner side cleaning pipe 8 and the outer side cleaning pipe 9 are provided in the filtration device to clean the inner and outer filter media 1 and 2 as required. As shown in FIGS. 1 and 2, the inner cleaning pipe 8 is provided along the inner peripheral surface of the inner filter medium 1, and a plurality of cleaning nozzles 8 </ b> A, 8 </ b> A,. The inner cleaning tube 8 is attached so as to face the peripheral surface. Similarly, the outer cleaning pipe 9 is provided along the outer peripheral surface of the outer filter medium 2, and the outer cleaning pipe 9A, 9A,... It is attached to the tube 9. Water or alkaline chemicals can be used as the cleaning liquid. During the cleaning, cleaning water is jetted from a plurality of cleaning nozzles 8A, 8A,..., 9A, 9A,. Thereby, the filtration surface of the inner side filter medium 1 and the outer side filter medium 2 is wash | cleaned, and clogging prevention or elimination of clogging is achieved. The washing water sprayed at the time of washing is stored as washing waste water together with the filtrate in the lower part of the lower casing 42 and is discharged from the filtrate discharge port 13.

  Further, although not shown, back pressure control means for performing back pressure control is provided. The back pressure control means executes drive control of the second motor with speed reducer M2 during the filtration operation. Such back pressure control means can be configured by a known control device such as a computer that stores and executes a predetermined program.

  In the thus configured filtration device, the filtration operation can be performed as follows. That is, the first motor M1 with a speed reducer is operated to integrally rotate the inner filter medium 1, the outer filter medium 2, and the annular rotating plate 20 in the same direction as the upward turning direction of the partition 3, and to feed the slurry to be processed. The slurry to be treated is pumped into the filtration space 4 through the pipe line 10.

  The slurry to be treated fed into the filtration space 4 is subjected to two-side filtration by the inner filter medium 1 and the outer filter medium 2. More specifically, the treated slurry fed from the treated slurry feed pipe 10 is in a state of low solid content and fluidity, and in the lower part of the filtration space 4, the inner filter medium 1 and the outer filter medium. Filtration concentration occurs through the openings in 2. As the concentration proceeds, the fluidity is lost and a cake is formed. The cake moves in the circumferential direction of the filtration space 4 by friction with the rotating inner and outer filter media 1 and 2. At this time, since the spiral partition 3 is disposed in the filtration space 4, the cake rotating along the inner and outer filter media 1, 2 interferes with the partition 3, When the feeding pressure is applied from below, it turns up around the axis. By this movement, solid-liquid separation is performed at the lower part of the filtration space 4 to form a cake. The cake is pressed and dehydrated at the upper part of the filtration space 4 and then pushed up from the upper part of the filtration space 4 to the discharge space 4X. The filtrate discharged to the inside of the inner filter medium 1 and the outer filter medium 2 by filtration is stored at the bottom of the lower casing 42 and discharged from the filtrate discharge port 13.

  The cake pushed up to the discharge space 4 </ b> X along each partition 3 is discharged onto the annular rotating plate 20 through each discharge port 24. At this time, on the rear side in the rotation direction of each discharge port 24, the cake located from the inner peripheral edge to the intermediate position on the annular rotary plate 20 is pushed in advance to the outer peripheral edge side by the outer guide plate 29. A cake discharge space is secured at the discharge position. The cake placed on the annular rotating plate 20 is pushed out from the annular rotating plate 20 to the outer discharge chute 44 by the common discharge guide 25 in the process of being rotated and transferred with the rotation of the annular rotating plate 20, and is outside the machine. To the next processing step via a conveyor.

  On the other hand, during the filtration operation, the back pressure control means adjusts the opening area of the discharge port 24 so that the back pressure of the filtration space becomes a predetermined set pressure. Specifically, in the case of the illustrated embodiment, the back pressure control means moves the opening adjuster 26 by driving the second motor M2 with a reduction gear in a predetermined direction when a non-detection signal is input from the non-contact sensor 30. . In this movement process, when the input signal from the non-contact sensor 30 changes to the detection signal of the detection unit 31, the driving of the second motor with speed reducer M2 is stopped to stop the movement of the aperture adjuster 26. Thereby, the opening area of the discharge port 24 is adjusted so that the back pressure of the filtration space becomes a predetermined set pressure. This control is preferably performed at the start of or prior to the filtration operation. Thus, even when the opening area is changed due to maintenance, failure, etc., during the filtration operation, the back pressure control means causes the back pressure of the filtration space to become a predetermined set pressure by the opening adjusting means. Since the opening area of the discharge port 24 can be adjusted, high dewatering performance can be easily maintained. And the above-mentioned form can exhibit sufficient effect with a very simple device composition and control form.

  However, with this alone, the back pressure fluctuates due to fluctuations in the dewatering properties of the cake during the filtration operation, and the dewatering performance cannot be stably maintained. Therefore, a pressure gauge (not shown) for measuring the back pressure in the filtration space 4 is used. The back pressure control means outputs the measurement signal to the back pressure control means, and the back pressure control means adjusts the opening area of the discharge port 24 so that the measurement value input from the pressure gauge at the time of filtration operation becomes the set pressure. It is also possible to adopt a form of feedback control. By performing such feedback control, finer aperture adjustment can be performed.

  More specifically, in the case of using a position detection unit that combines the non-contact sensor 30 and the detection unit 31 described above, it is necessary to provide the detection units 31 at a plurality of positions with intervals in the moving direction of the opening adjuster 26. As the number of detectors 31 increases, finer back pressure control is possible. Then, when the measured pressure of the pressure gauge is lower than the set back pressure, the control means drives the second motor M2 with a reduction gear, and the opening area of the discharge port 24 is increased until the detection signal of the detection unit 31 is input. The aperture adjuster 26 is moved in the decreasing direction and then stopped. When the measured pressure of the pressure gauge is higher than the set back pressure, the moving direction of the opening adjusting body 26 is only reversed. This movement is repeated within the moving range of the opening adjusting body 26 (preferably within the range in which the detection unit 31 can be detected) until the measured pressure of the pressure gauge reaches the set back pressure, thereby performing finer opening adjustment. It can be carried out.

  Such feedback control can be applied instead of the above-described fixed control, or can be combined with the above-described fixed control. In the case of the latter, the form which performs fixed control at the time of an operation start or prior to this, and performs feedback control after that is preferable.

<Others>
(A) In the above example, the inner peripheral edge and the outer peripheral edge of the partition 3 are close to or in contact with the filtration surfaces of the inner filter medium 1 and the outer filter medium 2, respectively. 4 is strongly exerted near the treated slurry inlets 10 and 11, so that the inner and outer peripheral edges of the partition 3 are at least the inner and outer filter media 1 near the treated slurry inlets 10 and 11 side. Any structure may be used as long as it is close to or in contact with each other.

(B) The partition 3 may have a uniform helical pitch in the entire filtration space 4, but may be configured to become narrower as it goes upward as shown in FIG. 6 (a). You can also. On the contrary, the spiral partition 3 may be configured such that the pitch interval becomes longer as it goes from the bottom plate 7B side of the casing 7 to the upper plate 7A side.

(C) Although the filtration space 4 which concerns on embodiment has shown the cyclic | annular thing which has the same cross-sectional area from the top to the bottom, the lower part of the filtration space 4 is a large-capacity filter in order to ensure a processing amount. In order to increase the chamber volume and to improve the dewatering efficiency in the upper part of the filtration space 4, it is also a preferable form to narrow the radial difference between the inner and outer filter media 1,2.
Specifically, as shown in FIG. 6A, the shape of the outer filter medium 2 remains the same, and the radial direction of the inner filter medium 1 is continuously changed from the treated slurry feed side to the cake discharge side. A shape that expands (substantially conical) or a shape that expands stepwise as shown in FIG. 6B (multistage cylindrical shape) can be proposed. Moreover, as shown in FIG.6 (c), the shape of the inner side filter medium 1 remains the same, and the radial direction of the outer side filter medium 2 is continuously reduced toward the cake discharge | emission side from the to-be-processed slurry delivery side. It is also possible to propose a shape that is reduced, or a shape that is reduced stepwise as shown in FIG.

(D) Even when the inner filter medium 1 and the outer filter medium 2 are rotated at the same angular velocity (° / sec), the peripheral speed (mm / sec) of each radius difference is generated, so that shear force is generated in the cake. Thus, dewatering efficiency is improved. For example, this shearing force is more effective for a slurry to be treated containing raw sludge having a high fiber content or mixed raw sludge. Depending on the cake properties, when a shearing force is applied, the cake may be fluidized, and conversely, the dewatering property may be impaired. In such a case, it is preferable to rotate the cake at a constant peripheral speed difference. In addition, a cake that has a dehydrating effect due to a shearing force and whose cake properties hardly change throughout the year can be rotated with a constant peripheral speed difference.
When the inner filter medium and the outer filter medium are driven independently as in the prior art, it is possible to further improve the dewatering efficiency by rotating the inner filter medium 1 and the outer filter medium 2 with a speed difference. Since this effect depends on the properties of the target cake, it is desirable to set the speed difference between the inside and outside according to the properties of the cake when operating in the optimum state. In particular, when the relative speed between the inner filter medium 1 and the outer filter medium 2 is large, the cake in the vicinity of the rapidly rotating filter surface (for example, the filter surface of the inner filter medium 1) is filtered with another filter surface (for example, the filter of the outer filter medium 2). The effect of migrating to the surface) side appears, and the mixing action in the cake occurs, so that the moisture content distribution in the filtration device can be made uniform. The inner filter medium 1 and the outer filter medium 2 do not necessarily need to be rotated, and only one of them may be rotated.

(F) In the above example, the axes of the filter media 1 and 2 are vertically oriented (along the vertical direction), the entire apparatus is vertically oriented, and the slurry to be treated is fed in a pressurized state from below to above. However, the axial centers of the filter media 1 and 2 may be laterally (along the horizontal direction), and the entire apparatus may be disposed laterally. In the horizontal direction, the inside of the apparatus may be moved only by the frictional force generated by the rotation of the inner filter medium 1 and the outer filter medium 2 without pumping the slurry to be treated. However, depending on the properties of the cake, the degree of progress of dehydration and the design of the filter chamber volume may not be balanced, and the cake filling rate may decrease. In this case, in the configuration in which the filtration device is arranged sideways (horizontal type), the filtrate is affected by gravity, so that the moisture content of the cake to be discharged is increased by leaching into a cake having a low filling rate. is there. On the other hand, when the axial center is vertically oriented and the entire apparatus is vertically oriented, and the slurry to be treated is fed in a pressurized state from below to above, the filtrate is drawn using gravity. It is possible to prevent leaching to the upper cake discharge side, and therefore, it is possible to eliminate unevenness (distribution) of the moisture content of the discharged cake and make it more uniform.

(G) Although the said example is an example applied to the form different from the thing of patent documents 3 and 4, this invention is applicable also to the thing of patent documents 3 and 4.

It is a longitudinal cross-sectional view of a filtration apparatus. It is the A section enlarged view of FIG. It is BB sectional drawing of FIG. It is CC sectional drawing of FIG. It is a perspective view of a partition. It is a longitudinal cross-sectional view which shows the outline of another filtration apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Inner filter medium, 1A ... Upper plate, 2 ... Outer filter medium, 3 ... Partition, 4 ... Filtration space, 5 ... Inner cylinder rotating shaft, 7 ... Casing, 7A ... Upper plate, 7B ... Bottom plate, 7C ... Inclined surface, 8 ... inner cleaning pipe, 9 ... outer cleaning pipe, 10 ... slurry to be treated, 13 ... filtrate discharge port, 14 ... filtration space outlet, 16 ... filtrate discharge space, 20 ... annular rotating plate, 24 ... release Outlet, 25 ... Discharge guide, 26 ... Opening adjuster, 29 ... Outer guide, 40 ... Main support, 41 ... Sub support, 42 ... Lower casing, 43 ... Upper casing, 44 ... Discharge chute, 45 ... Swivel fitting.

Claims (5)

A concentric arrangement of cylindrical or conical inner and outer filter media;
A spiral partition provided in a filtration space between the inner filter medium and the outer filter medium, and extending in a direction along the center of the inner filter medium while turning around the inner filter medium;
A rotational drive source that rotates the inner filter medium and / or the outer filter medium around its center,
The spiral partition is configured not to rotate,
The slurry to be treated is fed from one end side of the filtration space, the filtrate that has passed through the inner filter medium and the outer filter medium is discharged to the outside, and the cake formed by this filtration is transferred along the partition A filtration device configured to be discharged to the other end side of the filtration space,
While having an outlet for discharging the cake from the filtration space, an opening adjusting means for adjusting the opening area of the outlet,
Back pressure control means for adjusting the opening area of the discharge port by the opening adjusting means so that the back pressure of the filtration space becomes a predetermined set pressure during the filtration operation;
A filtration device comprising:   The said back pressure control means adjusts the opening area of the said discharge port to the area set beforehand based on the correlation with the back pressure of the said filtration space, and the opening area of the said discharge port. Filtration equipment.   The back pressure control means includes a pressure gauge for measuring the back pressure of the filtration space, and the back pressure control means is configured to release the release pressure by the opening adjustment means so that a measured value by the pressure gauge becomes the set pressure during filtration operation. The filtration apparatus of Claim 1 or 2 which adjusts the opening area of an exit. As the opening adjusting means, there are provided an opening adjusting body which is movable along a surface having the discharge port so that an area of a portion overlapping with the discharge port is changed, and a position detecting unit of the opening adjuster. And
The back pressure control means moves the opening adjusting body according to the position detection result by the position detecting means, and changes the area of the portion overlapping the opening adjusting body and the discharge opening, thereby opening the discharge opening. To adjust the area,
The filtration apparatus of any one of Claims 1-3. A concentric arrangement of cylindrical or conical inner and outer filter media;
A spiral partition provided in a filtration space between the inner filter medium and the outer filter medium, and extending in a direction along the center of the inner filter medium while turning around the inner filter medium;
A rotational drive source that rotates the inner filter medium and / or the outer filter medium around its center,
The spiral partition is configured not to rotate, using a filtration device,
The slurry to be treated is fed from one end side of the filtration space, the filtrate that has passed through the inner filter medium and the outer filter medium is discharged to the outside, and the cake formed by this filtration is transferred along the partition Letting it be discharged to the other end side of the filtration space,
While providing a discharge port for discharging the cake from the filtration space, providing an opening adjusting means for adjusting the opening area of the discharge port,
During filtration operation, the opening area of the discharge port is adjusted by the opening adjusting means so that the back pressure of the filtration space becomes a predetermined set pressure.
The filtration method characterized by the above-mentioned.

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