JP7022280B2 - How to operate the filter press - Google Patents

Description

The present invention relates to a method for operating a filter press having a diaphragm filter plate that requires medium- to long-term pressing and dehydration treatment in various production processes such as tap water / industrial water sludge treatment, chemical industry, and paper pulp industry.

Conventionally, in a filter press, undiluted solution is pressed into a filtration chamber for high-pressure dehydration, filtered and dehydrated, and then a pressure fluid is pressed into a diaphragm filter plate to be pressed and dehydrated. The pressure pump is continuously operated during squeezing to maintain the pressure.
For squeezing and dehydration, Patent Document 1 discloses a squeezing and dehydrating method in which compressed air is supplied to a diaphragm to perform primary squeezing, and then pressure water is supplied to perform high-pressure secondary squeezing.

Further, Patent Document 2 discloses a technique of using a pressure tank to maintain the squeezing pressure of pressure water, providing a large-capacity diaphragm in a filter press, and using the large-capacity diaphragm as a substitute for the pressure tank. ing.

Special Fair 02-12122 Gazette Japanese Patent No. 4911369

In the filter press of Patent Document 1, it is necessary to operate the pressure water pump for a long time in order to keep the pressing pressure of the pressure water constant when the pressing time is long.
Further, in the filter press of Patent Document 2, in order to shorten the operating time of the pressure water pump, large-capacity diaphragms are provided at both ends of the filter press as a pressure tank, but there is a problem that the filter press becomes large. ..

Furthermore, since a large-capacity diaphragm supplies a large amount of compressed air and pressure water compared to a normal diaphragm, a large amount of air and water are required, and the power of the pump that supplies them is also large. ..

The present invention provides a method for operating a filter press that utilizes a diaphragm chamber as a pressure tank by squeezing and dehydrating with compressed air without using a large-capacity diaphragm.

A press-fitting step of injecting the undiluted solution into a filtration chamber formed of a large number of filter plates and a diaphragm filter plate to generate a dehydrated cake, an air-squeezing step of supplying compressed air to the diaphragm chamber formed in the filtration chamber, and air-squeezing. In the operation method of the filter press including the hydraulic pressing step of supplying compressed water to the diaphragm chamber after the step, the thickness of the dehydrated cake produced in the filtration chamber due to the expansion of the diaphragm is 1/4 to 2/2 / the thickness of the filtration chamber. The time for the three widths is set in advance by a timer, and one or more of the diaphragm filter plates is used as a pressure filter plate, and the undiluted solution is not pressed into the filtration chamber formed by the pressure filter plate in the press-fitting step, and the air is not pressed. By continuing the squeezing process for a predetermined time , a sufficient amount of air can be filled in the diaphragm even if an external pressure tank is not provided.

Since the volume of the diaphragm chamber of the pressure filter plate is 1/50 to 1/20 of the total volume of the other diaphragm chambers, the number of times of driving the pressure water pump in the water pressing step is reduced.

Since a diaphragm of normal size is used as a pressure tank, a large-capacity diaphragm is not required and the filter press can be miniaturized.
Further, by supplying compressed air to the diaphragm until the dehydrated cake has a width of 1/4 to 2/3 of the filtration chamber, a large amount of compressed air corresponding to the width of 3/4 to 1/3 of the filtration chamber is put into the diaphragm. Can be retained.
Since the pressure drop of the pressure water is slowed down by the compressed air, it is not necessary to operate the pressure water pump frequently, and the operation time can be shortened.

It is a flow chart of the filter press which concerns on this invention. Similarly, it is a partial vertical perspective view of a parallel filter plate and a diaphragm filter plate . Similarly, it is a conceptual diagram of a filter press in which a pressure filter plate is arranged at one end of parallel filter plates.

FIG. 1 is a flow chart of a filter press according to the present invention.
In the filter press, a pair of guide rails 3 are bridged to the front frame 1 and the rear frame 2, and a large number of filter plates 4 and diaphragm filter plates 5 are alternately supported on the guide rails 3 to form a parallel filter plate 4. A pressure filter plate 6 for increasing the compressed air reservoir is arranged at one end of the diaphragm filter plate 5.
A tightening cylinder 7 arranged on the rear frame 2 is connected to the movable head 8, and the filter plate 4 and the diaphragm filter plate 5 arranged in parallel by the tightening cylinder 7 are opened and closed.

FIG. 2 is a partial vertical perspective view of a parallel filter plate and a diaphragm filter plate.
A pair of filter cloths 10 are suspended in a filtration chamber 9 formed by the filter plate 4 and the diaphragm filter plate 5, and the undiluted solution is press-fitted between the filter cloth 10 and the supply port 11 penetrating the filter plate 4 and the diaphragm filter plate 5. do.
A diaphragm 5a that can be expanded and contracted is stretched on the surface of the diaphragm filter plate 5. The undiluted solution supplied to the filtration chamber 9 is squeezed by expanding the diaphragm 5a, and solid-liquid separation is performed with the filter cloth 10.

FIG. 3 is a conceptual diagram of a filter press in which a pressure filter plate is arranged at one end of parallel filter plates.
The diaphragm filter plate 5 has a diaphragm 5a stretched on the surface thereof to form a diaphragm chamber 12 inside. Further, a pressure filter plate 6 is arranged at one end of the filter plate 4 and the diaphragm filter plate 5 which are arranged in parallel. A diaphragm 6a is stretched on the surface of the pressure filter plate 6 , and a diaphragm chamber 12a is formed between the pressure filter plate 6 and the diaphragm 6a.

The diaphragm 5a is expanded by supplying a pressure fluid to the diaphragm chamber 12. In the present invention, all the diaphragm chambers 12 are communicated with each other, and the diaphragm chamber 12 of the diaphragm filter plate 5 and the diaphragm chamber 12a of the pressure filter plate 6 are used as a pressure tank. After supplying compressed air, the pressure fluid supplies pressure water to expand the diaphragm 5a.

The diaphragm chamber 12 squeezes the sludge in the filtration chamber 9 by supplying compressed air for a predetermined time, and fills the air required as a pressure tank. The compressed air is supplied in a sufficient amount because the pressure is gradually reduced in the water pressing step S3 described later. By supplying a sufficient amount of compressed air to the diaphragm chamber 12a over a predetermined time, the number of times the pressure water pump 17 is operated can be reduced.

The volume of the diaphragm chamber 12a of the pressure filter plate 6 is 1/50 to 1/20 of the total volume of the diaphragm chambers 12 of the diaphragm filter plates 5 arranged in parallel. By providing the diaphragm chamber 12a having the capacity, the compressed air can be sufficiently held, so that the number of times of driving the pressure water pump 17 in the water pressing step S3 is reduced.

In this embodiment, one pressure filter plate 6 is arranged at one end of the parallel filter plate 4 and the diaphragm filter plate 5, but a plurality of pressure filter plates 6 can also be arranged. At this time, a plurality of pressure filter plates 6 are assembled and arranged at one end of the four rows of filter plates, or a plurality of pressure filter plates 6 are dispersed and arranged between the filter plates 4.

As shown in FIG. 3, the pressure water supply pipe 14 and the compressed air pipe 15 are connected to the diaphragm chamber 12 of the diaphragm filter plate 5 and the diaphragm chamber 12a of the pressure filter plate 6.
As shown in FIG. 1, a pressure water pump 17 for pumping water from the water supply tank 16 and a pressure water valve 18 for turning on and off the pressure water are arranged in the pressure water supply pipe 14. An air compressor 20 for supplying compressed air to the air tank 19 connected to the compressed air pipe 15 and a compressed air valve 21 for turning on and off the compressed air supplied to the compressed air pipe 15 are arranged.

Compressed air and pressure water are supplied to the diaphragm chamber 12 by the air compressor 20 and the pressure water pump 17, and the dehydrated cake is squeezed. The air compressor 20 supplies compressed air of 0.7 to 0.85 MPa to the diaphragm chamber 12, and the pressure water pump 17 supplies pressure water of 1.3 to 1.6 MPa.

Further, the filtrate is discharged from the discharge pipe 22 communicating with the filter plate 4.
By supplying the compressed air for a predetermined time, the sludge in the filtration chamber 9 is air-squeezed, and the diaphragm 5a is filled with the compressed air. The time for the dehydrated cake to become 1/4 to 2/3 width of the thickness (volume) of the filtration chamber 9 by air pressing is obtained in advance, and the time for continuing the air pressing is set. More preferably, the energy efficiency of the water pressing step S3 is maximized by setting the time for the dehydrated cake to be 1/3 width of the thickness of the filtration chamber 9.
When the control panel 24 detects that the compressed air has been supplied for a predetermined time by a timer, it controls the pressure water pump 17, the pressure water valve 18, the air compressor 20, and the compressed air valve 21, and switches the air squeezing to the water squeezing.

As shown in FIGS. 1 and 2, the stock solution supply pipe 26 in which the stock solution press-fitting pump 25 is arranged communicates with the filtration chamber 9 between the filter plate 4 and the diaphragm filter plate 5.
In FIG. 3, the filter plates 4 and the diaphragm filter plates 5 are alternately arranged in parallel in order to form the filtration chamber 9, but filtration is performed by forming the filtration chamber 9 in parallel with only the diaphragm filter plates 5. It is possible to squeeze from both sides of the chamber 9 with the diaphragm 5a.

The filter press used in the present invention is configured as described above, and the squeezing filtration method thereof is shown below .
In the air pressing step S2 , the supply time of compressed air in which the thickness of the dehydrated cake is 1/3 of the thickness of the filtration chamber 9 is set in advance.
The tightening cylinder 7 is driven in advance, and the parallel filter plate 4 and the diaphragm filter plate 5 are closed to form the filtration chamber 9.

Press-fitting process (S1)
The undiluted solution is press-fitted into the filtration chamber 9 of the filter press from the undiluted solution press-fitting pump 25 via the undiluted solution supply pipe 26 to perform filtration. At this time, the undiluted solution is not supplied to the pressure chamber 13. Further, no fluid is supplied to the diaphragm chamber 12, and the filtration chamber 9 is filled with the undiluted solution.
The filter cloth 10 stretched in the filtration chamber 9 separates the liquid from the undiluted solution to generate a dehydrated cake, and the filtrate is discharged to the outside of the filtration chamber 9 through the discharge pipe 22.

Air pressing process (S2)
After stopping the press-fitting of the undiluted solution, the air compressor 20 is driven to operate the compressed air valve 21 to supply compressed air to the diaphragm chamber 12 of the diaphragm filter plate 5 and the diaphragm chamber 12a of the pressure filter plate 6. The pressure is increased to 0.85 MPa. After boosting the pressure, the air compressor 20 is stopped.
As the diaphragm chambers 12 and 12a expand due to the compressed air, the dehydrated cake formed in the filtration chamber 9 is compressed, and the liquid content is further discharged from the dehydrated cake. Since the internal pressure of the diaphragm chambers 12 and 12a decreases with the discharge of the filtrate, the air compressor 20 is driven again when the pressure decreases to 0.7 MPa. Compressed air is supplied to the diaphragm chambers 12 and 12a by the air compressor 20, and the internal pressure is increased to 0.85 MPa.

When the supply of compressed air is repeated and the timer detects that a predetermined time has elapsed, the compressed air valve 21 is closed and the air compressor 20 is stopped.
By continuing the air pressing step S2 for a predetermined time, the thickness of the dehydrated cake becomes 1/3 width of the thickness of the filtration chamber 9.

Water squeezing process (S3)
After closing the compressed air valve 21, the pressure water pump 17 is driven. The pressure water valve 18 is opened and the pressure water is press-fitted into the diaphragm chamber 12. The internal pressure of the diaphragm chamber 12 is increased to 1.5 MPa, the pressure water valve 18 is closed, and the pressure pump 17 is stopped.

The pressure water causes the diaphragm chamber 12 to become even higher in pressure, and water is further separated from the dehydrated cake in the filtration chamber 9 by the filter cloth 10. The separated water is discharged from the filtration chamber 9 through the discharge pipe 22. Since compressed air is supplied to the diaphragm chambers 12 and 12a, the internal pressure of the diaphragm chambers 12 and 12a gradually decreases as the water is discharged from the filtration chamber 9.

When the internal pressure of the diaphragm chambers 12 and 12a drops to 1.4 MPa with the progress of squeezing, the pressure water pump 17 is driven again and the pressure water valve 18 is opened to reduce the internal pressure of the diaphragm chambers 12 and 12a. The pressure is increased to 5 MPa. Water squeezing is performed by repeating this operation multiple times.

After repeating the ON / OFF operation of the pressure water pump 17 according to the change in the internal pressure of the diaphragm chambers 12 and 12a, the pressure water valve 18 is closed and the pressure water pump 17 is stopped to cause the diaphragm chambers 12 and 12a. The internal pressure is adjusted to be within a certain width, and the operating time of the pressure water pump 17 at the time of squeezing and dehydrating is shortened.

A predetermined time during which the number of operations of the pressure water pump 17 can be reduced is set in advance while considering the thickness at which the dehydrated cake can be easily discharged, and the water pressing step S3 is terminated when the predetermined time elapses.

Pressure water drainage process (S4)
After the water squeezing with the pressure water is completed, the pressure water valve 18 is opened, and the compressed air in the diaphragm chambers 12 and 12a is used to discharge the pressure water in the diaphragm chambers 12 and 12a. The pressure water is discharged to the water supply tank 16 through the pressure water supply pipe 14. After that, the compressed air valve 21 is opened to bring the diaphragm chambers 12 and 12a to normal pressure.

Dewatered cake discharge step (S5)
The tightening cylinder 7 is contracted to open the filter plate 4 and the diaphragm filter plate 5, and the dehydrated cake formed in the filtration chamber 9 is discharged to the outside of the machine. When the filter press is continuously operated, the filter plate 4 and the diaphragm filter plate 5 are closed to form the filtration chamber 9 again, and the process returns to the press-fitting step S1.

In the present invention, in the air pressing step S2, the diaphragm chambers 12 and 12a are used as the pressure tank by supplying a large amount of compressed air to the diaphragm chambers 12 and 12a of the pressure chamber 13. In the air pressing step S2, air pressing is continued for a predetermined time in which the thickness of the dehydrated cake is, for example, 1/3 width of the filtration chamber 9, and compressed air having a capacity of 2/3 width of the filtration chamber 9 is transferred to the diaphragm chamber 12. We are supplying. Therefore, compressed air can be held without separately providing a large-capacity pressure tank.

Therefore, in the water squeezing step S3, the internal pressure of the diaphragm chambers 12 and 12a gradually decreases according to the discharge of the filtrate, and the frequency of starting the pressure water pump 17 in order to maintain the internal pressure of the diaphragm chambers 12 and 12a constant. The startup time can be significantly reduced.

4 Filter plate 5 Diaphragm filter plate
5a diaphragm
6 Pressure filter plate 9 Filtration chamber 12, 12a Diaphragm chamber S1 Press-fitting process S2 Air pressing process S3 Water pressing process

Claims (2)

A press-fitting step (S1) in which a stock solution is press-fitted into a filtration chamber (9) formed of a large number of filter plates (4) and a diaphragm filter plate (5) to produce a dehydrated cake,
An air squeezing step (S2) for supplying compressed air to the diaphragm chamber (12) formed in the filtration chamber (9), and
In the operation method of the filter press including the water pressing step (S3) of supplying pressure water to the diaphragm chamber (12) after the air pressing step (S2).
A timer predetermines the time during which the thickness of the dehydrated cake produced in the filtration chamber (9) due to the expansion of the diaphragm (5a) becomes 1/4 to 2/3 width of the thickness of the filtration chamber (9).
One or more of the diaphragm filter plates (5) is used as a pressure filter plate (6).
The undiluted solution was not press-fitted into the filtration chamber (9) formed by the pressure filter plate (6) in the press-fitting step (S1).
The operation method of the filter press, wherein the air pressing step (S2) is continued for a predetermined time. The filter press according to claim 1 , wherein the volume of the diaphragm chamber (12a) of the pressure filter plate (6) is 1/50 to 1/20 of the total volume of the other diaphragm chambers (12). How to drive.

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