JP7755789B2 - Filter press filter cloth damage detection device - Google Patents

Description

The present invention relates to a filter cloth damage detection device for a filter press that detects which filter cloth is damaged based on the filtrate being discharged from a filter press with multiple filtration chambers arranged in parallel.

In conventional filter presses, the filtrate separated by the filter cloth in each filtration chamber is discharged into an external filtrate tank or similar via a common discharge channel located on the outside of each filter plate. Therefore, if a filter cloth is damaged and filtrate containing a large amount of suspended solids leaks out, it is unclear which of the many filter cloths is damaged, so operation must be stopped and the filter cloths in each filtration chamber must be visually inspected. However, with this method, it is unclear which filter cloth is damaged, and inspections take time.

Furthermore, if operation continues without noticing that the filter cloth is damaged, the pressure cannot be maintained in the filtration chamber with the damaged filter cloth, resulting in an imbalance in the pressure being forced into the filtration chambers of the entire filter press, making it impossible to achieve sufficient dewatering. The filtrate containing a large amount of suspended solids is discharged to the outside, increasing the environmental burden. Furthermore, filtrate containing large amounts of suspended solids from the filter floor surface concentrates in the connecting holes and flows into the discharge channel at high dynamic pressure (high speed), causing wear to the connecting holes and discharge channel, particularly due to the hard particles in the suspended solids, and requiring the replacement of parts.

Patent Document 1 discloses, in Figure 1, a filter press filter cloth damage detection device in which the lower part of each filtrate discharge pipe communicating with the filtration chamber is branched into two branch pipes, a three-way valve is provided at the branch, a turbidity meter is installed in one branch pipe, and the other branch pipe is connected to a shared collecting pipe. Furthermore, Figure 3 discloses a filter press filter cloth damage detection device in which the lower part of each filtrate discharge pipe communicating with the filtration chamber is branched into two branch pipes, a three-way valve is provided at the branch, one branch pipe is connected to a shared collecting pipe, and the other branch pipe is connected to a shared branch pipe, and turbidity is measured using a turbidity meter.

Patent Document 2 discloses a filter cloth breakage detection device for a filter press. A remote detection device consisting of a transmission-type optical sensor is placed on the side of the filter plate row. When the filter cloth is damaged and the detection rod protrudes to the side of the filter plate, the light beam from the optical sensor is interrupted and an alarm is activated.

Japanese Utility Model Application Publication No. 58-116005 Patent No. 5582359

The technology shown in Figure 1 of Patent Document 1 requires a turbidity meter in each filtration chamber, which increases costs and the risk of breakdowns and malfunctions. Furthermore, the technology shown in Figure 3 of Patent Document 1 requires only one turbidity meter, but requires switching the filtrate discharged from each filtration chamber using a three-way valve and checking each one individually. It also takes time and effort to identify damaged filter cloths.

The technology in Patent Document 2 detects damage to filter cloths using an optical sensor that shines light along the filter plate row, but requires a detection rod that protrudes from each filter plate in the event of damage, which increases costs and the risk of malfunctions. Furthermore, to identify damaged filter cloths, it is necessary to visually check which filter plate has a protruding detection rod.

The present invention provides a filter cloth damage detection device for a filter press that can detect filter cloth damage with high accuracy while the filter press is in operation and identify which filter cloth in parallel filtering chambers has been damaged using a single measuring device.

The present invention relates to a filter press in which filtrate separated into solid and liquid by filter cloths sandwiched between filter plates is discharged into a collecting pipe through the filtrate passages of each filter plate. The filter press is equipped with a connected detection path in which the filtrate discharged from each filtration chamber is collected, and a detection device which emits a pulse to a probe extending from a main body fixed to one end of the detection path to the vicinity of the other end within the detection path, the pulse being reflected at the boundary between the clear filtrate discharged from the undamaged filter cloths and the filtrate with a higher turbidity than the clear filtrate discharged from the damaged filter cloth, and converts the propagation time until the reflected wave is received by the main body into a distance and outputs the converted pulse. This makes it possible to detect damage to the filter cloths with high accuracy and to easily identify the damaged filter cloths.

The detection path is a collecting pipe formed by closing the filter plates and connecting the drain outlets of each filter plate in the direction of their arrangement, or a collecting pipe installed alongside each filter plate. Installing the main body of the detection device at the upstream end where the filtrate flows down makes it easy to improve existing devices.

The detection path is formed by connecting a portion of the filtrate passages of each filter plate by closing the filter plates, and the irradiation wave is emitted perpendicular to the direction of the filtrate flow, allowing for accurate position detection.

By irradiating the area near the connection between the detection path and the filtrate passage, or by installing a flow-down guide tube consisting of a T-shaped pipe at the connection between the detection path and the filtrate passage, and aligning the opening of the T-shaped pipe with the upstream and downstream sides of the collecting pipe, and inserting the detection device probe inside it, high-concentration filtrate can be detected in the collecting pipe.

The filter cloth damage detection device for a filter press according to the present invention is configured as described above, and can identify which filter cloth in multiple parallel filtration chambers has broken during operation using a single measuring device. There is no need to stop the filter press for inspection, open the filter plates, and visually check. Furthermore, there is no need for complicated operations such as switching the filtrate, and detection is easy.

1 is a schematic side view of a filter press according to the present invention. FIG. FIG. FIG. 10 is a schematic explanatory diagram of detection along a detection path. FIG. 10 is a schematic explanatory diagram of detection using a detection path according to another embodiment of the present invention. FIG. 10 is a schematic explanatory diagram of detection using a detection path according to another embodiment 2. FIG. 10 is a schematic side view of a filter press according to another embodiment 3. FIG. 10 is a front view of a filter plate according to another embodiment 3.

FIG. 1 is a schematic side view of a filter press according to the present invention.
The filter press 1 according to the present invention is mounted on a pair of parallel guide rails 4 supported by a front frame 2 and a rear frame 3. A plurality of filter plates 5 having filtering floor surfaces 5a on the front and back sides, and filter cloths 6 stretched over the filtering floor surfaces 5a, are attached to the guide rails 4. The plurality of filter plates 5 are mounted on the guide rails 4 so as to be movable forward and backward.

An opening/closing device 7 is supported on the rear frame 3, and the filter plate 5 is closed by extending the opening/closing device 7 and pressing the movable head 8 toward the front frame 2. When raw liquid is supplied to the filtration chamber 9 between the closed filter plates 5, 5, the raw liquid is separated into solid and liquid by the filter cloth 6, and the solid matter captured by the filter cloth 6 is dewatered while forming a cake layer within the filtration chamber 9. The filtrate passes through the filter cloth 6 and is discharged to the outside through the filtrate passage 10 on the filter floor surface 5a.

After dehydration is complete, the opening/closing device 7 is retracted to open the filter plates 5. Each filter plate 5 can be opened simultaneously at a predetermined interval determined by the connecting link 11. The cake inside the filtering chamber 9 is then dropped and discharged outside the machine. The opening/closing device 7 that opens and closes the filter plates 5 can be a hydraulic cylinder, an electric cylinder, or the like. The filter plates 5 may also be opened one by one in sequence.

FIG. 2 is a schematic cross-sectional view of the filtration chamber.
Each filter plate 5 has a concave filtering surface 5a. When the filter plates 5 are closed, the filtering chambers 9 are defined between the opposing filtering surfaces 5a of adjacent filter plates 5. When a raw liquid is supplied from a raw liquid supply path 12 through a raw liquid passage 13 between the filter cloths 6, 6 of the filtering chambers 9, the raw liquid undergoes solid-liquid separation by the filter cloths 6, and the filtrate that passes through the filter cloths 6 flows into a filtrate passage 10 provided below the filtering surface 5a. If the filter cloth 6 is damaged during this process, solids will pass through the damaged portion of the filter cloth 6 and flow into the filtrate passage 10 along with the filtrate. By configuring one filtering surface 5a as a diaphragm, the filtering chambers 9 are compressed by the diaphragm during solid-liquid separation, reducing the moisture content of the solids.

FIG. 3 is a front view of the filter plate.
One end of a filtrate passage 10 for discharging the filtrate is open below the filter floor surface 5a where the filtrate collects, and the other end passes through the thickness of the filter plate 5 and connects to a drain port 14 formed on the outer side of the filter plate 5. The drain port 14, which communicates with the filtrate passage 10, is provided so as to penetrate the filter plate 5 in the thickness direction. When the filter plate 5 is closed, the drain ports 14 of each filter plate 5 are connected to each other along the arrangement direction to form a collecting pipe 15. The filtrate separated into solid and liquid in each filtering chamber 9 is discharged from each filtrate passage 10 through the collecting pipe 15 and to the outside through a discharge pipe 16 connected to the front frame 2. In this way, a large amount of filtrate separated into solid and liquid by the filter cloth 6 is pressurized by a diaphragm or the like, flows from the filtrate passage 10 to the drain port 14, and then flows down the collecting pipe 15 toward the front frame 2.

In this embodiment, the filtrate passages 10 are arranged symmetrically on adjacent filter plates 5, 5, and the filtrate is discharged to the drain ports 14 arranged on both outer sides of the filter plate 5, respectively. However, the filtrate passages 10 of each filter plate 5 may be connected to only one of the drain ports 14 or to the drain ports 14 on both outer sides.
In this embodiment, the collecting pipe 15 is integrated with the filter plates 5. However, as shown in FIGS. 7 and 8 , a collecting pipe 15a may be provided in parallel with the row of filter plates 5, and the filtrate may be discharged from each filtering chamber 9 to the collecting pipe 15a via a flexible tube or the like.

FIG. 4 is a schematic explanatory diagram of detection along a detection path.
The filtrate discharged from each filtration chamber 9 is collected in a common detection path 17, and the position of the suspension that has flowed into the detection path 17 is measured by a detector 18. In this embodiment, the detection path 17 that detects the filtrate with the detector 18 is a collecting pipe 15, and the detector 18 is provided at one end of the collecting pipe 15. The detector 18 can detect the inside of the collecting pipe 15 linearly and longitudinally toward the other end, and detects the position of the interface between the filtrate of a predetermined turbidity discharged from each filtration chamber 9 into the collecting pipe 15 and the clear filtrate.

The detection device 18 is composed of a main body 22 and a probe 23 extending from the main body 22. The main body 22 is fixed to one end of the detection path 17, and the probe 23 is inserted up to the vicinity of the other end of the detection path 17. A pulse such as a microwave is propagated from the main body 22 to the probe 23, and the pulse is reflected by the boundary surface of different liquids due to the difference in dielectric constant, and the propagation time until it is received by the main body 22 is converted into a distance and output.
In this embodiment, a guided pulse type level meter is used as the detection device 18, and a probe 23 is extended from a main body 22 fixed to the movable head 8, which is upstream of the filtrate flowing down the collecting pipe 15, toward the front frame 2 inside the collecting pipe 15.

If the filter cloth 6 is not damaged, the filtrate discharged from the connection 19 with each filtrate passage 10 to the collecting pipe 15 is homogeneous and has no difference in dielectric constant. Therefore, a pulse is reflected at the tip of the probe 23 of the detection device 18.

If a portion of the filter cloth 6 is damaged and highly turbid filtrate containing suspended solids from the filtration chamber 9 is discharged into the collecting pipe 15, a difference in dielectric constant occurs at the boundary between the highly turbid filtrate discharged from the connection 19 with the filtrate passage 10 into the collecting pipe 15 and the clear filtrate, causing a portion of the pulse propagating through the probe 23 to be reflected. The main body 22 of the detection device 18 receives the reflected pulse and outputs the distance to the discharge position of the highly turbid filtrate, instantly determining that the filter cloth 6 in the filtration chamber 9 corresponding to the output distance is likely to be damaged.

It is desirable to adjust the detection sensitivity of the detector 18 in advance, depending on the raw liquid to be separated into solid and liquid in the filter press 1, so that damage to the filter cloth 6 can be detected with high accuracy.

When the detector 18 detects an abnormality in the filter cloth 6, an alarm may be sounded on an operation panel or the like. Furthermore, the distance from the detector 18 to each connection 19 may be input in advance, and the corresponding filtration chamber 9 or filter cloth 6 may be output on an operation panel or the like, making it possible to detect the discharge position of high-turbidity filtrate discharged from each filtrate passage 10 to the collecting pipe 15.

Note that while this embodiment uses electromagnetic pulses as the pulses, any pulse that is reflected due to the difference in dielectric constant at the boundary between filtrate of a certain turbidity and clear filtrate can be applied to the detection device 18 of the present invention.

FIG. 5 is a schematic explanatory diagram of detection along a detection path according to another embodiment 1.
The filtrate discharged from the filtrate passage 10 into the collecting pipe 15 flows downward within the collecting pipe 15 toward the front frame 2. In particular, the filtrate discharged from the downstream filtering chamber 9 into the collecting pipe 15 is swept along with the filtrate flowing down through the collecting pipe 15 from the upstream side, so it flows downstream immediately after being discharged from the connecting part 19 into the collecting pipe 15, which can cause an error in the position where the probe 23 of the detection device 18 comes into contact with the liquid. Therefore, it is desirable to extend the probe 23 near the connecting part 19 between the filtrate passage 10 and the collecting pipe 15, as shown in (a).

(b) shows an embodiment in which a downflow guide pipe 21 is provided at the connection 19 between the filtrate passage 10 and the collecting pipe 15. In this embodiment, a small-diameter T-shaped pipe is connected to each connection 19 inside the collecting pipe 15, and the probe 23 of the detection device 18 is inserted inside it, making it possible to detect the filtrate concentration before it becomes diluted. Because the openings of the T-shaped pipe are aligned upstream and downstream of the collecting pipe 15, a single probe 23 can detect the filtrate in all of the vertically arranged downflow guide pipes 21.

FIG. 6 is a schematic explanatory diagram of detection along a detection path according to another embodiment 2.
A detection path 17 is formed to connect a portion of each filtrate passage 10 in the front-to-rear direction of the collecting pipe 15. As with the collecting pipe 15, the filter plate 5 is closed to form an integrated detection path 17. A probe of a detection device 18 extends from one end of the detection path 17 to the other end within the detection path 17. The detection path 17 is linear and has a smaller diameter than the collecting pipe 15, and the end is configured to be bag-shaped, so that the filtrate in the detection path 17 does not flow toward the adjacent filtration chamber 9.

The probe 23 of the detection device 28 can be selected as needed, such as a rod type or rope type. Furthermore, when extending the probe 23 into the detection path 17, it may be supported as appropriate as long as it does not interfere with detection.

Detection of the filtrate is performed during the injection process, in which the raw liquid is injected into the filtration chamber 9, and during the squeezing process, in which the dehydrated cake in the filtration chamber is squeezed using a diaphragm or the like after the injection process. After the detection path 17 is filled with water, a pulse is emitted from the main body 22 of the detection device 18 to the probe 23. Because the amount of filtrate decreases over time during the injection and squeezing processes, detection may be performed for a predetermined time from the start of each process. The interval at which the detection device 18 emits pulses is set in advance.

The filter cloth damage detection device for a filter press of this invention performs accurate detection by utilizing pulse reflection caused by differences in the dielectric constant of suspended matter in the filtrate, and can identify the position of the filter cloth in the vertically aligned filtering chamber from which suspended matter is being discharged. Therefore, this invention is extremely useful as a filter cloth damage detection device for multi-chamber filter presses for drinking water sludge, sewage sludge, industrial wastewater sludge, etc.

REFERENCE SIGNS LIST 1 filter press 5 filter plate 6 filter cloth 9 filtering chamber 10 filtrate passage 14 drain outlet 15, 15a collecting pipe 17, 22 detection path 18 detection device 19 connection part 21 flow down guide pipe 22 main body part 23 probe

Claims (6)

A filter press (1) in which a filtrate obtained by solid-liquid separation using a filter cloth (6) sandwiched between filter plates (5, 5) is discharged into a collecting pipe (15) through a filtrate passage (10) of each filter plate (5...),
a communicating detection path (17) in which filtrates discharged from each filtration chamber (9...) are collected;
a detection device (18) that transmits a pulse to a probe (23) that extends from a main body (22) fixed to one end of the detection path (17) to the vicinity of the other end of the detection path (17) and that reflects at the boundary between a clear filtrate discharged from an undamaged filter cloth (6) and a filtrate that is more turbid than the clear filtrate discharged from a damaged filter cloth (6), converting the propagation time until the reflected wave is received by the main body (22) into a distance and outputting the result;
A filter cloth damage detection device for a filter press, comprising: The filter cloth damage detection device for a filter press according to claim 1, characterized in that the detection path (17) is a collecting pipe (15) formed by closing the filter plates (5) to connect the drain outlets (14) of each filter plate (5...) to each other along the arrangement direction, and the main body (22) of the detection device (18) is provided at the upstream end where the filtrate flows down. 2. The filter cloth damage detection device for a filter press according to claim 1, wherein the detection path (17) is a collecting pipe (15a) arranged in parallel with each filter plate (5...), and a main body (22) of the detection device (18) is provided at the upstream end where the filtrate flows down. 2. The filter cloth damage detection device for a filter press according to claim 1, wherein the detection path (17) is formed by connecting a part of the filtrate passages (10) of each filter plate (5...) by closing the filter plate (5). 4. The filter cloth breakage detection device for a filter press according to claim 2 or 3, wherein a probe (23) is extended near a connection (19) between the detection path (17) and the filtrate passage (10). 4. The filter cloth damage detection device for a filter press according to claim 2 or 3, characterized in that a flow-down guide pipe (21) consisting of a T-pipe is provided at a connection (19) between the detection path (17) and the filtrate passage (10), the openings of the T-pipe are aligned with the upstream and downstream of the collecting pipe (15), and a probe (23) of the detection device (18) is inserted inside the T-pipe.