JP5585890B2 - Filter cloth shrinkage detection method and detection device in filter press - Google Patents

Description

  The present invention relates to a filter cloth traveling type filter press for treating clean water sludge, sewage sludge, industrial wastewater sludge, and the like, and more particularly to a filter cloth shrinkage detection method and a detection device in a filter press for detecting shrinkage of a filter cloth.

Conventionally, filter presses for treating large-capacity sludge have run a filter cloth suspended between filter plates to shorten the cake discharge time in order to shorten the filtration cycle time. This filter cloth expands and contracts greatly when it is dry and wet, and when it is new and clogged. In particular, when clogged, the amount of shrinkage becomes 3% or more. For example, in the case of a 2 m filter cloth, the amount of shrinkage is 60 mm or more. The filter cloth connects the top and bottom core plates with a chain and circulates the filter board. When the filter cloth shrinks, the upper sprocket that hangs the chain and the lower sprocket that hangs the filter cloth A large tension is applied to the return roll. When the tension is increased in this way, problems such as bending of the core for supporting the filter cloth and an increase in the load on the driving device for running the filter cloth occur.
For example, as a lifting device that can freely lift and lower the filter cloth to adjust the expansion and contraction of the filter cloth, a clamp provided with a screw rod is connected to the drive band that fastens the upper edge of the filter cloth, and the lower end of the filter cloth is In Japanese Patent Application Laid-Open No. H11-260260, the present applicant has proposed a filter cloth suspending device that adjusts expansion and contraction of a filter cloth with a nut engaged with a holding portion of a clamp and screwed into a screw rod.
And as the filter cloth tension adjusting device against the shrinkage of the filter cloth, for example, the guide roll in which the lower end portion of the filter cloth is hung around the elongated hole of the bracket hanging below the filter plate is inserted and supported, and the position of the guide roll Patent Document 2 discloses a filter cloth suspending device that moves a spring up and down with a spring.

Actual Fairness 8-963 Japanese Utility Model Publication No. 62-36489

In the conventional filter cloth suspending device, a traveling band such as a drive chain is connected to the filter cloth in an endless manner, and the filter cloth is suspended between an upper sprocket and a lower return roll so as to be movable up and down. The filter cloth suspending device of Patent Document 1 can easily attach and remove the consumable filter cloth that needs to be replaced periodically, but the shrinkage of the filter cloth is measured each time. It takes time and effort.

The filter cloth suspending device disclosed in Patent Document 2 can automatically adjust the running load against the shrinkage of the filter cloth by pressing a guide roll wound around the filter cloth with a spring. As the amount of shrinkage increases, the amount of compression of the spring increases and the tension of the filter cloth increases. For this reason, the traveling load becomes high, and it is necessary to adjust the filter cloth tension.
The present invention provides a filter cloth shrinkage detection method and a detection device in a filter press that can detect filter cloth shrinkage and easily adjust the tension of the filter cloth.

According to the filter press shrinkage detection method of the filter press according to the present invention, a pair of filter cloths are disposed between filter plates arranged in parallel so as to be openable and closable, and a filter is attached to one end of a drive chain wound around a sprocket provided above the filter plate. In the filter press that connects the upper end of the cloth, hangs the lower end of the filter cloth on a pair of return rolls provided below the filter plate and connects to the other end of the drive chain, the filter cloth can be raised and lowered, Calculate the correlation between the amount of contraction of the filter cloth and the movement time in advance to determine the set time, measure the movement time when the predetermined part of the filter cloth moves to the predetermined position from the start of movement of the filter cloth, and move An alarm is issued when the time is longer than the set time, and the filter cloth shrinkage can be detected and dealt with before the filter press performance or function is affected. If the set time is set in multiple stages, appropriate measures such as adjusting the tension of the drive chain and replacing the filter cloth can be performed with respect to the filter cloth shrinkage.

The filter cloth shrinkage detecting device in the filter press according to the present invention is arranged such that a pair of filter cloths are arranged between filter plates arranged in parallel so as to be openable and closable, and a filter is attached to one end of a drive chain wound around a sprocket provided above the filter plate. In the filter press that connects the upper end of the cloth, hangs the lower end of the filter cloth on a pair of return rolls provided below the filter plate and connects to the other end of the drive chain, the filter cloth can be raised and lowered, A filter cloth raising detection device or a filter cloth lowering detection device for detecting the start of raising and lowering of the filter cloth, and a filter cloth movement detecting device for detecting that a predetermined portion of the filter cloth has moved to a predetermined position are provided in advance. A calculation unit that calculates a correlation expression between the shrinkage amount of the filter cloth and the movement time, determines a set time, measures the movement time of the filter cloth, a determination unit that compares the movement time (T) and the set time, and a movement time A warning to be issued when is over the set time Those having a control device configured with a, before they affect the operation of the filter press, it is possible to detect the contraction of the filter cloth, it is not necessary to measure the periodic filter cloth shrinkage amount.

Further, for example, if the filter cloth movement detection device is disposed on the front frame and the lower filter cloth core of the filter cloth is detected, the movement time of the filter cloth can be calculated with high accuracy. Further, since the adjustment device for adjusting the tension of the drive chain is provided at the lower end portion of the drive chain, the tension of the drive chain can be easily adjusted.

The filter cloth shrinkage detection method and the detection device in the filter press according to the present invention are configured as described above, and the filter cloth shrinkage can be automatically detected before the filter press operation is disturbed. There is no need for the operator to measure the filter cloth shrinkage. Specifically, it measures the moving time for a predetermined part of the filter cloth to move to a predetermined position from the start of descent of the filter cloth, and can also be applied to an existing filter press. If correlation data between the shrinkage amount of the filter cloth and the moving time is obtained in advance, the shrinkage amount of the filter cloth (the degree of clogging) can be estimated from the moving time of the filter cloth, and the time when the limit shrinkage amount can be predicted.

It is a schematic side view at the time of closing of a filter press concerning this invention. Similarly, it is a front view of a filter plate. Similarly, it is a perspective view of the filter cloth hung between the filter plates. Similarly, it is a longitudinal cross-sectional view of a filtration chamber. Similarly, it is the schematic of the drive device of a filter cloth. Similarly, it is a principal part enlarged view of an adjustment apparatus. Similarly, it is a schematic view when the filter cloth is located at the rising limit. Similarly, it is a schematic view when the filter cloth is positioned in the middle of descending. Similarly, it is a flowchart for issuing warnings in stages.

The filter cloth shrinkage detection device in the filter press according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic side view of the filter press having the filter cloth shrinkage detection device. The filter press includes a plurality of filter plates 4 that can move in the front-rear direction while being slidably mounted on a side rail 3 bridged between the front frame 1 and the rear frame 2, and these filter plates 4. The filtration chamber 6 is formed by the filter cloth 5 suspended so as to cover the filtration floor surface 4a.

A slide shaft 7 is provided above the plurality of filter plate rows along the filter plate row. A bevel gear slide 8 on which the filter cloth 5 is suspended is fitted into the slide shaft 7 so as to be slidable in the axial direction. ing.
A tightening cylinder 9 is supported on the rear frame 2, the filter plate 4 is closed by extending the tightening cylinder 9 and pressing the movable head 10 toward the front frame 1, and the closed filter plates 4, 4. When the stock solution is supplied to the filtration chamber 6 in the meantime, the filtrate passes through the filter cloth 5 and is discharged to the outside. The solid matter captured by the filter cloth 5 is dehydrated while forming a cake layer.

After dehydration, the clamping cylinder 9 is contracted to open the filter plate 4. The filter plates 4 can be simultaneously opened at a predetermined interval determined by the connecting link 11. And the drive device 12 of the filter cloth 5 is operated, and the dehydrated cake is discharged while the filter cloth 5 is traveling downward. The filter plates 4 that are arranged in parallel may be ones in which the filter plates and the diaphragm plates are alternately arranged in parallel.

FIG. 2 is a front view of a filter cloth suspending device suspended between the filter plates. The filter device 5 suspending device 13 includes an upper suspending device 13 a disposed above the filter plate 4 and a lower portion. And a lower suspension device 13b disposed in the space. The upper suspension device 13 a is connected to a pair of upper brackets 14, 15 erected on both shoulders of the filter plate 4, a filter cloth drive shaft 16 supported on these, and one end of the filter cloth drive shaft 16. And a pair of sprockets 18 fitted to both ends of the filter cloth drive shaft 16. The upper bracket 14 is fixed to one shoulder of the filter plate 4, and a slide gear housing 17 is supported on the upper end of the upper bracket 14. On the other hand, the lower suspension device 13b includes a pair of lower brackets 19 and 19 suspended from the lower ends on both sides of the filter plate 4, and two return rolls 20 supported on these and a cleaning pipe 21 having a nozzle.

FIG. 3 is a perspective view of the filter cloth hung between the filter plates. The pair of rectangular filter cloths 5 and 5 are formed by joining the upper end portions of each other and then folding them back and stitching them together. , And a pair of cylindrical lower end edges 23a stitched by folding back each lower end. An upper filter cloth mandrel 22 and a lower filter cloth mandrel 23 that are longer than the width of the filter cloth 5 are inserted into the upper end edge 22a and the lower end edge 23a, respectively, and are fastened. A drive chain 27 having a Tightener bolt at its end is connected to both ends of the upper filter cloth mandrel 22. An undiluted solution supply plate 25 is sandwiched between the upper center portions of the pair of filter cloths 5. The liquid supply plate 25 is provided with a raw liquid passage 26 penetrating from the front surface to the rear surface, and a liquid supply passage 26 a penetrating from the lower inner peripheral surface of the raw liquid passage 26 to the lower end of the liquid supply plate 25.
Detection rods 39 and 39 are fixed to the drive chain 27 at predetermined positions, and an upper limit and a lower limit at which the filter cloth 5 moves up and down are detected by a filter cloth rising detection device 40 and a filter cloth lowering detection device 41, respectively. doing.

FIG. 4 is a longitudinal sectional view of the filter chamber of the filter press. A sprocket 18 connected to a drive source is provided above the filter plate 4 and a pair of return rolls 20 and 20 are provided below the filter plate 4. doing. An upper filter cloth mandrel 22 inserted through the upper ends of the pair of filter cloths 5 and 5 is connected to one end of a drive chain 27 wound around the sprocket 18. The lower ends of the filter cloths 5 and 5 are hung around the pair of return rolls 20 and 20 in the direction away from each other, and the lower filter cloths at the lower ends of the filter cloths 5 and 5 suspended from the filter bed 4a before and after the filter plate 4. The core metal 23 is locked to the locking tool 28. The locking tool 28 is connected to the other end of the drive chain 27 via the adjusting device 29. A sprocket 18 connected to the drive device 12 is rotated so that the filter cloth 5 suspended between the opened filter plates 4 and 4 can be raised and lowered.

When the parallel filter plates 4 are closed, a pair of liquid supply plates 25 suspended on the filter cloth 5 are sandwiched between the front and rear filter plates 4 and 4 and suspended on the filter bed 4 a of the filter plate 4. A filtration chamber 6 is formed between the filter cloths 5 and 5. The stock solution passage 26 of the liquid supply plate 25 is communicated with the stock solution supply path 30 formed in the upper center portion of the filter plate 4, and the stock solution is press-fitted into the filtration chamber 6 between the filter cloths 5 and 5 to perform solid-liquid separation. After dehydration, the parallel filter plates 4 are opened, and the pair of filter cloths 5 and 5 are moved downward. The cake attached to the filter cloth 5 is peeled off when the pair of return rolls 20 and 20 below the filter plates 4 and 4 are bent and moved away from each other. Reference numeral 21 is a nozzle for injecting wash water to the filter cloth 5.

As shown in FIG. 5, the bevel gear slide 8 that is pivotally supported by the slide gear housing 17 meshes with the input bevel gear 31 that is fitted to the end of the filter cloth drive shaft 16. This meshing state is always maintained during the opening / closing operation of the filter plate 4. A slide shaft 7 having a polygonal cross section extending in the front-rear direction of the filter press is fitted to the bevel gear slide 8 so as not to rotate with respect to the bevel gear slide 8 and to be slidable in the axial direction.
The slide gear housing 17 and the upper brackets 14 and 15 that support the slide gear housing 17 are alternately disposed on the left and right shoulders of the parallel filter plates 4 so as not to interfere with each other between the adjacent filter plates 4 when the plate is closed. Yes. At this time, the sprockets 18 of the filter cloth drive shafts 16 of the filter plates 4 are arranged on the same straight line.

As shown in FIG. 1, the pair of slide shafts 7 slidably supported on the upper bracket 14 of the filter plate 4 via the slide gear housing 17 are arranged in the front and rear direction of the filter press on the upper left and right sides of the filter plate 4. Extending parallel to each other. The front and rear ends of each slide shaft 7 are rotatably supported by the front frame 1 and the rear frame 2, respectively. The front ends of the pair of slide shafts 7 are interlocked and connected to a drive device 12 capable of forward and reverse rotation installed on the rear frame 2 via conversion gears .
By driving the drive device 12, the left and right slide shafts 7 can be rotated by a predetermined amount, and the filter cloths 5 between the parallel filter plates 4 can be moved up and down all at once.

FIG. 6 is an enlarged view of the main part of the adjusting device. A turnbuckle 33 is connected to the lower end of the drive chain 27, and one of the pair of Tightener bolts 35, 36 provided with a joint link 34 is screwed. Match. The titner bolt 35 is fixed to the turnbuckle 33 with a nut 37 screwed into the titner bolt 35. The other Tightener bolt 36 is inserted into the locking tool 28 and fixed with nuts 38 and 38. The turnbuckle 33 is graduated, and the tension of the drive chain 27 can be adjusted by adjusting the insertion length of the Tightener bolt 35 with the joint link 34.

FIG. 7 is a schematic view when the filter cloth is located at the upper limit, and the filter cloth movement detection device 50 is disposed above the front frame 1. The filter cloth movement detection device 50 is disposed toward the opposite filter plate 4 and detects the filter cloth 5 moving up and down between the front frame 1 and the filter plate 4.

In the state where the filter plates 4 are closed (FIG. 1), as shown in FIG. 7, the filter cloth 5 is raised to the uppermost part (ascending limit) so as to be positioned in front of the filter bed 4a. Yes. Specifically, the upper filter cloth mandrel 22 suspending the upper part of the filter cloth 5 rises to the vicinity of the sprocket 18, and the lower filter cloth mandrel 23 suspending the lower part of the filter cloth 5 is returned. It descends to the vicinity of the roll 20. When the filter plate 4 is closed and the stock solution is supplied to the filtration chamber 6, the filter cloth 5 always stops at this position, so that the stock solution passage 26 of the supply plate 25 suspended from the filter cloth 5 is filtered. The undiluted solution supply path 30 of the plate 4 is communicated. Therefore, the rising limit of the filter cloth 5 is detected by a member that does not contract so that the position of the supply plate 25 does not deviate even when the filter cloth 5 contracts and the entire length becomes short. Specifically, as shown in FIG. 3, a detection rod 39 is fixed at a predetermined position of the drive chain 27, and a filter cloth rise detection device 40 is placed on the front frame 1. When the drive chain 27 engaged with the sprocket 18 rotates and the filter cloth 5 is located at the upper limit, the detection rod 39 fixed to the drive chain 27 comes into contact with the filter cloth rise detection device 40 from above and detects it. After the detection, the driving device 12 for driving the filter cloth 5 is stopped, and the process proceeds to the next step.

Since the upper limit of the filter cloth 5 is set as described above, when the filter cloth 5 contracts, the lower filter cloth core of the filter cloth 5 as shown by a broken line when the filter plate 4 is closed as the filter plate 4 is closed. The gold 23 comes close to the return roll 20. Since the drive chain 27 has been slackened in advance, the drive chain 27 is tensioned in accordance with the contraction of the filter cloth 5, and the load on the drive device 12 that causes the filter cloth 5 to travel does not increase.
The upper limit of the filter cloth 5 may be detected by detecting the positions of the upper filter cloth core 22 and the liquid supply plate 25 that are less affected by the contraction of the filter cloth 5.

FIG. 8 is a schematic view of the filter cloth being lowered. When the filter cloth 5 is lowered, the upper filter cloth core 22 is lowered to the lower part between the filter plates 4 and 4, and the lower filter cloth core 23 is the upper part of the filter plate 4. It rises to the vicinity. The lowering limit of the filter cloth 5 is detected by a filter cloth lowering detection device 41 disposed on the front frame 1 with a detection rod 39 fixed to a predetermined position of the drive chain 27. When the drive chain 27 engaged with the sprocket 18 rotates and the filter cloth 5 is located at the lower limit, the detection rod 39 fixed to the drive chain 27 comes into contact with the filter cloth lowering detection device 41 from below to detect. After the detection, the driving device 12 for driving the filter cloth 5 is stopped, and the process proceeds to the next step. The filter cloth 5 is always in this position when descending, so that the cake attached to the filter cloth 5 is reliably peeled by inverting the filter cloth 5 with the return roll 20. When the detection of the filter cloth lowering detection device 41 is removed, it is understood that the filter cloth 5 has started to rise.

As shown in FIG. 7, when the filter cloth 5 contracts, the lower end edge 23a of the filter cloth 5 moves toward the return roll 20 when the plate is opened (when the filter cloth 5 starts to descend). When the descent of the filter cloth 5 is started from this state, it takes time until the predetermined portion of the filter cloth 5 is lowered to a predetermined position as compared with the time when the filter cloth 5 is not contracted. The closer the lower end edge 23a of the filter cloth 5 is, the more the time required to descend to a predetermined position becomes longer because the position at the start of lowering has moved greatly.

When the filter cloth 5 starts to descend, a signal is transmitted from the filter cloth rise detection device 40 to the control device 51. Thereafter, when a predetermined portion of the filter cloth 5 is lowered to a predetermined position, the filter cloth movement detection device 50 detects the predetermined portion and transmits a detection signal to the control device 51.
In this embodiment, the filter cloth movement detection device 50 detects when the filter cloth 5 is lowered, but it may be detected when the filter cloth 5 is raised. In that case, it detects the rise of the filter cloth descending detecting device 41 Niteronuno 5, a predetermined portion of the filter cloth 5, when raised to a predetermined position, detected by the filter cloth movement detection device 50. It is also possible to detect the descent limit of the filter cloth 5 at a predetermined portion of the filter cloth movement detection device 50 Delo cloth 5.

The control device 51 calculates a movement time T from the start of movement of the filter cloth 5 until it is detected by the filter cloth movement detection device 50, and a determination section that compares the movement time T with a preset set time T0. 51b and a command unit 51c that issues a warning when the movement time T is equal to or longer than the set time T0.

FIG. 9 is a flowchart for issuing an alarm in two stages. If necessary, it may be set in multiple stages to issue an alarm. As an initial setting for detecting the contraction of the filter cloth 5, in this embodiment, the upper limit time required for the filter cloth 5 to move from the ascending limit to a predetermined position is set in two stages.

When the opening process of the filter plate 4 is completed, the drive device 12 for lowering the filter cloth 5 is operated, and all the filter cloths 5 are lowered all at once. At this time, the detection rod 39 fixed to the drive chain 27 is separated from the filter cloth rising detection device 40, and a signal is transmitted to the control device 51.

The filter cloth movement detection device 50 disposed on the front frame 1 detects that a predetermined portion of the filter cloth 5 has moved to a predetermined position, and transmits a detection signal at this time to the control device 51. In the present embodiment, the filter cloth movement detection device 50 is disposed above the front frame 1, and when the lower filter cloth metal core 23 of the filter cloth 5 has moved to the position facing the filter cloth movement detection device 50. Sending detection signal.
The filter cloth movement detection device 50 may be disposed on the rear frame 2 or the filter plate 4 as necessary. Moreover, although the non-contact type proximity switch is used for the filter cloth movement detection device 50, a contact type limit switch or the like can be appropriately selected as necessary.

In the control device 51, the time from the signal reception from the filter cloth rise detection device 40 to the signal reception of the filter cloth movement detection device 50 is measured by the calculation unit 51a. Thereby, the movement time T until the filter cloth 5 moves from the descent start to a predetermined position is calculated. The descent start signal may detect the start of operation of the drive device 12.

The determination unit 51b compares the travel time T calculated by the calculation unit 51a with the first set time T0 'preset at the time of initial setting. If the moving time T required for moving the filter cloth 5 is within the set time T0 ', the process proceeds to the next step (filter cloth rising, filter plate closing plate, undiluted solution supply, pressing). If the movement time T required to move the filter cloth 5 is equal to or longer than the set time T0 ', the issuing unit 51c issues a first alarm. Any alarm may be used as long as it is noticed by a worker who performs maintenance and management, such as well-known sound, light, and display on the operation panel.

When the first alarm is issued, after the predetermined operation, the subsequent process is canceled and the operation of the filter press is stopped. In this embodiment, the filter press is stopped after the filter cloth 5 is once raised to the ascent limit.
When the driving device 12 stops, the tension of the filter cloth 5 is adjusted. Specifically, the lower filter cloth mandrel 23 moves to the return roll 20 side due to the shrinkage of the filter cloth 5, and there is no room for slack in the drive chain 27. Therefore, the adjusting device 29 is extended to give the drive chain 27 a slack.
If the relational expression between the shrinkage amount of the filter cloth 5 and the movement time is calculated in advance, the shrinkage amount (clogging degree) of the filter cloth 5 can be estimated from the movement time T required when the filter cloth 5 is lowered. The amount by which the adjusting device 29 is extended during the first alarm can be determined.

After adjusting the adjusting device 29, the filter plate 4 is closed and the stock solution is supplied and dehydrated. The filter cloth 5 further shrinks along with the dehydration process. Similar to the first stage, the movement time T required for the lowering of the filter cloth 5 is calculated by the calculation unit 51a, and compared with the second set time T0 ″ preset in the initial setting by the determination unit 51b. If the moving time T required for the time is within the set time T0 ″, the process proceeds to the next step (filter cloth rising, filter plate closing, stock solution supply / dehydration). If the movement time T required for the movement of the filter cloth 5 is equal to or longer than the set time T0 ″, the issuing unit 51c issues a second alarm.

When the second alarm is issued, the filter press operation is stopped after canceling the next process after a predetermined operation.
In the present embodiment, it is assumed that the setting time T0 ″ of the second stage has no adjustment allowance for the adjustment device 29, or the filter cloth 5 is clogged severely and impairs the dehydration performance. If the warning is issued, replace the filter cloth 5.
After the filter cloth 5 is replaced, the determination is made at the first set time T0 ′ which is the initial setting.

Since the filter cloth shrinkage detection device in the filter press according to the present invention can detect the tension of the drive chain and the replacement of the filter cloth before the performance and function of the filter press are affected, the maintenance management becomes easy. From the relationship between the operation time and the shrinkage amount of the filter cloth, it is possible to estimate the time when the limit shrinkage amount is reached, so it is possible to obtain stock at an appropriate time without occupying the place by storing it in the filter cloth storage for a long time. . It can be applied to all filter presses from small to large, and special filter cloth shapes can be ordered in advance at an appropriate time.

DESCRIPTION OF SYMBOLS 1 Front frame 4 Filter board 5 Filter cloth 18 Sprocket 20 Return roll 23 Lower filter cloth metal core 27 Drive chain 29 Adjustment apparatus 40 Filter cloth rise detection apparatus 41 Filter cloth fall detection apparatus 50 Filter cloth movement detection apparatus 51 Control apparatus 51a Calculation part 51b Discriminating part 51c Commanding part T Travel time T0 Set time

Claims (5)

A pair of filter cloths (5, 5) are arranged between filter plates (4, 4) arranged in parallel to be openable and closable, and a drive chain (27 is wound around a sprocket (18) provided above the filter plate (4). ) Is connected to the upper end of the filter cloth (5, 5), and the lower end of the filter cloth (5, 5) is hung on a pair of return rolls (20, 20) provided below the filter plate (4). In a filter press that is rotated and connected to the other end of the drive chain (27), and the filter cloth (5) can be raised and lowered.
The correlation time between the contraction amount of the filter cloth (5) and the movement time is calculated in advance to determine the set time (T0),
From the start of movement of the filter cloth (5)
Measure the movement time (T) when the predetermined part of the filter cloth (5) moves to the predetermined position,
A filter cloth shrinkage detection method in a filter press, wherein a warning is issued when a movement time (T) is equal to or longer than a set time (T0). The filter cloth shrinkage detection method for a filter press according to claim 1, wherein the set time (T0) is set in multiple stages. A pair of filter cloths (5, 5) are arranged between filter plates (4, 4) arranged in parallel to be openable and closable, and a drive chain (27 is wound around a sprocket (18) provided above the filter plate (4). ) Is connected to the upper end of the filter cloth (5, 5), and the lower end of the filter cloth (5, 5) is hung on a pair of return rolls (20, 20) provided below the filter plate (4). In a filter press that is rotated and connected to the other end of the drive chain (27), and the filter cloth (5) can be raised and lowered.
A filter cloth rise detection device (40) or a filter cloth fall detection device (41) for detecting the start of raising and lowering of the filter cloth (5);
While disposing a filter cloth movement detection device (50) for detecting that a predetermined part of the filter cloth (5) has moved to a predetermined position,
The correlation time between the amount of contraction of the filter cloth (10) and the movement time is calculated in advance to determine the set time (T0),
A calculation unit (51a) for measuring the travel time (T) of the filter cloth (5);
A determination unit (51b) for comparing the movement time (T) and the set time (T0);
A filter cloth shrinkage detection device in a filter press, comprising: a control device (51) configured with a command unit (51c) that issues an alarm when the movement time (T) is equal to or longer than a set time (T0). The filter cloth movement detection device (50) is disposed on the front frame (1),
The filter cloth shrinkage detecting device in the filter press according to claim 3, wherein the lower filter cloth mandrel (23) of the filter cloth (5) is detected. The filter cloth shrinkage detection device for a filter press according to claim 3 or 4, further comprising an adjustment device (29) for adjusting a tension of the drive chain (27) at a lower end portion of the drive chain (27).

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