JP2020049453A - Operational method of filter press and pressure tank-integrated filter press - Google Patents

Abstract

To provide an operational method of a filter press and a pressure tank-integrated filter press where a pressure tank is not needed by utilizing the diaphragm of the filter press as the pressure tank.SOLUTION: In an operational method of a filter press including a press-in step S1 forming a dewatering cake by pressing-in a stock solution into a filter chamber 9 formed with a lot of filter plates 4 and diaphragm filter plates 5, an air compression step S2 feeding compressed-air into a diaphragm chamber 12 formed in the filter chamber 9 and a water compression step S3 feeding pressure water into the diaphragm chamber 12 after the air compression step S2, the air compression step S2 is continued until the thickness of the dewatering cake formed in the filter chamber 9 by the expansion of a diaphragm 5a becomes 1/4-2/3 of the thickness of the filter chamber 9, a large amount of the compressed-air can be held in the diaphragm and then a pressure tank is not needed outside.SELECTED DRAWING: Figure 3

Description

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

Conventionally, in a filter press, in order to perform high-pressure squeezing and dewatering, the undiluted solution is pressed into the filtration chamber and filtered and dewatered. In order to maintain the pressure, the pressure pump is continuously operated during the squeezing.
Patent Literature 1 discloses a compression dehydration method in which compressed air is supplied to a diaphragm to perform primary compression, and then pressurized water is supplied to perform high-pressure secondary compression.

Patent Document 2 discloses a technique in which a pressure tank is used to maintain the compression pressure of pressurized water, a large-capacity diaphragm is provided in a filter press, and a large-capacity diaphragm is used as a substitute for the pressure tank. ing.

Japanese Patent Publication No. 02-12122 Japanese Patent No. 4911369

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

Furthermore, large-diameter diaphragms require a large amount of air and water to supply a large amount of compressed air and pressurized water as compared to a normal diaphragm, and the power of a pump that supplies them is also large. .

The present invention provides a method of operating a filter press that uses a diaphragm chamber as a pressure tank by compression dehydration with compressed air without using a large-capacity diaphragm.

A press-fitting step in which the undiluted solution is pressed into a filtration chamber formed by a number of filter plates and diaphragm filter plates to generate a dewatered cake; an air-pressing step of supplying compressed air to a diaphragm chamber formed in the filtration chamber; A water pressing step of supplying pressurized water to the diaphragm chamber after the step, and the operating method of the filter press, wherein the air pressing step is such that the thickness of the dewatered cake generated in the filtration chamber by the expansion of the diaphragm is the thickness of the filtration chamber. By continuing until the width becomes 1/4 to 2/3, a large amount of compressed air can be held in the diaphragm, and there is no need to provide an external pressure tank.

Any one or more of the diaphragm filter plates may be used as a pressure filter plate, and the holding amount of the compressed air can be increased by not pressing the stock solution into the filtration chamber formed by the pressure filter plate in the press-fitting step.

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 the pressure water pump is driven in the water pressing step is reduced.

The thickness of the dewatered cake can be determined by calculating the thickness of the dewatered cake based on the flow rate of the filtrate discharged from the filtration chamber, the concentration of the stock solution, and the supply amount of the stock solution.

In a filter press that presses a stock solution into a filtration chamber formed by a number of filter plates and a diaphragm filter plate to generate a dewatered cake, at least one of the diaphragm filter plates is used as a pressure filter plate, and the diaphragm filter plate and the pressure filter are used. A compressed air pipe for supplying compressed air to a diaphragm chamber formed on the plate and a pressure water supply pipe for supplying pressurized water are connected, and the undiluted solution supply pipe 26 is provided only to the filtration chamber formed between the filter plate and the diaphragm filter plate. , A large amount of compressed air can be held in the diaphragm, and there is no need to provide an external pressure tank.

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

A flow meter is provided in the discharge pipe for discharging the filtrate from the filtration chamber, and the thickness of the dewatered cake in the filtration chamber is calculated based on the filtrate flow rate measured by the flow meter, and the thickness of the dewatered cake is the thickness of the filtration chamber. When the width becomes 1/4 to 2/3, by providing a control panel for switching between a compressed air valve of a compressed air pipe and a pressure water valve of a pressure water supply pipe, water is supplied in a state where compressed air is sufficiently held. Move on to the pressing process.

The pressure filter plate is disposed at one end of the filter plate and the diaphragm filter plate, and the diaphragm stretched over the pressure filter plate is a thin film rubber, so that the manufacturing cost of the pressure filter plate can be reduced.

Since a normal-sized diaphragm is used as a pressure tank, a large-capacity diaphragm is not required, and the size of the filter press can be reduced.
Also, by supplying compressed air to the diaphragm until the dewatered cake becomes 1/4 to 2/3 of the width of the filtration chamber, a large amount of compressed air for 3/4 to 1/3 of the width of the filtration chamber is introduced into the diaphragm. Can be held.
Since the pressure drop of the pressurized water is moderated by the compressed air, it is not necessary to frequently operate the pressure water pump, and the operation time can be reduced.

It is a flow figure of the filter press concerning the present invention. Similarly, it is a partial longitudinal perspective view of a filter plate and a diaphragm arranged in parallel. Similarly, it is a conceptual diagram of a filter press in which a pressure filter plate is arranged at one end of a parallel filter plate.

FIG. 1 is a flowchart of a filter press according to the present invention.
In the filter press, a pair of guide rails 3 are bridged between a front frame 1 and a rear frame 2, and a 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. At one end of the diaphragm filter plate 5, a pressure filter plate 6 for increasing the compressed air pool is provided.
A tightening cylinder 7 disposed on the rear frame 2 is connected to the movable head 8 and opens and closes the filter plate 4 and the diaphragm filter plate 5 arranged in parallel by the tightening cylinder 7.

FIG. 2 is a partial longitudinal perspective view of a filter plate and a diaphragm filter plate arranged in parallel.
A pair of filter cloths 10 is suspended from a filter chamber 9 formed by the filter plate 4 and the diaphragm filter plate 5, and the undiluted solution is pressed into the filter cloth 10 from a supply port 11 penetrating the filter plate 4 and the diaphragm filter plate 5. I do.
The diaphragm filter plate 5 is provided with a diaphragm 5a which can expand and contract on the surface. The undiluted solution supplied to the filtration chamber 9 is squeezed by expanding the diaphragm 5a, and solid-liquid separation is performed by the filter cloth 10.

FIG. 3 is a conceptual diagram of a filter press in which a pressure filter plate is disposed at one end of a parallel filter plate.
The diaphragm filter plate 5 has a diaphragm 5a stretched on the surface and a diaphragm chamber 12 formed therein. Further, a pressure filter plate 6 is provided at one end of the filter plate 4 and the diaphragm filter plate 5 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 5a.

By supplying a pressure fluid to the diaphragm chamber 12, the diaphragm 5a is expanded. In the present invention, all the diaphragm chambers 12 are communicated, 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 the compressed air, the pressure fluid supplies the pressurized water to expand the diaphragm 5a.

The diaphragm chamber 12 is supplied with compressed air until the thickness of the dewatered cake becomes 1/4 to 2/3 of the thickness of the filtration chamber, and is expanded, so that the required amount of air as a pressure tank is filled. In addition, by expanding the diaphragm chamber 12 until the thickness of the dewatered cake becomes 1/3 width of the thickness of the filtration chamber 9, the energy efficiency of the water pressing step S3 described later is the highest.

The volume of the diaphragm chambers 12a of the pressure filter plates 6 is set to 1/50 to 1/20 of the total volume of the diaphragm chambers 12 of the diaphragm filter plates 5 arranged in parallel. Since the compressed air can be sufficiently held by providing the diaphragm chamber 12a having the above volume, the number of times the pressure water pump is driven in the water pressing step S3 is reduced.
The space formed between the pressure filter plate 6 and the filter plate 4 is referred to as a pressure chamber 13, and the pressure chamber 13 is used as a space for expanding the diaphragm 6a without supplying a stock solution. Since the diaphragm 6a is not used for squeezing the dewatered cake, it does not require strength and may be a thin film rubber.

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

As shown in FIG. 3, a pressure water supply pipe 14 and a 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 in a water supply tank 16 to a pressure water supply pipe 14 and a pressure water valve 18 for turning on and off the pressure water are provided. An air compressor 20 for supplying compressed air to an 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 provided.

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

The filtrate is discharged from a discharge pipe 22 communicating with the filter plate 4, and the flow rate of the filtrate is detected by a flow meter 23 provided in the discharge pipe 22.

The control panel 24 calculates the amount of filtrate from the flow rate detected by the flow meter 23, and controls the pressure water pump 17, the pressure water valve 18, the air compressor 20 and the compressed air valve 21 based on the calculated amount of filtrate. At 24, the compressed air pressure in the diaphragm chamber 12 is controlled.

As shown in FIGS. 1 and 2, a stock solution supply pipe 26 provided with a stock solution press-fit pump 25 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 to form the filtration chamber 9. However, by forming the filtration chamber 9 with only the diaphragm filter plates 5 arranged in parallel, the filtration 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 its squeezing filtration method is described below.
The thickness of the filtration chamber 9 and the solid content concentration of the stock solution are measured in advance.
The tightening cylinder 7 is driven in advance, and the filter plate 4 and the diaphragm filter plate 5 arranged in parallel are closed to form a filtration chamber 9.

Press-in process (S1)
The undiluted solution is injected into the filtration chamber 9 of the filter press from the undiluted solution injection pump 25 via the undiluted solution supply pipe 26 to perform filtration. At this time, the stock solution is not supplied to the pressure chamber 13. Further, no fluid is supplied to the diaphragm chamber 12, and the undiluted solution fills the filtration chamber 9.
The filter cloth 10 stretched in the filtration chamber 9 separates the liquid from the undiluted solution, a dewatered cake is generated, and the filtrate is discharged out of the filtration chamber 9 through the discharge pipe 22.

Air pressing process (S2)
After stopping the injection of the undiluted solution, the air compressor 20 is driven, the compressed air valve 21 is operated, and compressed air is supplied 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 the pressure increase, the air compressor 20 is stopped.
The compressed air expands the diaphragm chambers 12 and 12a, compresses the dewatered cake formed in the filtration chamber 9, and further discharges liquid from the dewatered cake. Since the internal pressure of the diaphragm chambers 12 and 12a decreases with the discharge of the filtrate, when the pressure drops to 0.7 MPa, the air compressor 20 is driven again. Compressed air is supplied to the diaphragm chambers 12 and 12a by the air compressor 20 to increase the internal pressure to 0.85 MPa.

The filtrate is discharged from the discharge pipe 22, and the flow rate of the filtrate is detected by the flow meter 23 of the discharge pipe 22.
The thickness (volume) of the dehydrated cake formed in the filtration chamber 9 is continuously calculated based on the detected flow rate of the filtrate, the solid content concentration of the stock solution, and the supply amount of the stock solution.
By continuing the air compression, the filtrate is discharged and the thickness of the dewatered cake is reduced. When the thickness of the dewatered cake is calculated to be 1/3 of the thickness of the filtration chamber 9, the compressed air valve is closed and the air compressor 20 is stopped.

If the thickness of the dewatered cake does not become 1/3 of the thickness of the filtration chamber 9 within a predetermined time, the air pressing step S2 ends, and the process proceeds to the next step.

Water pressing process (S3)
After closing the compressed air valve 21, the pressure water pump 17 is driven. The pressure water valve 18 is opened to pressurize the pressure water into the diaphragm chambers 12, 12a. The internal pressure of the diaphragm chambers 12 and 12a is increased to 1.5 MPa, the pressure water valve 18 is closed, and the pressure water pump 17 is stopped.

The pressure of the diaphragm chambers 12 and 12 a is further increased by the pressurized water, and the moisture is further separated from the dewatered 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 is gradually reduced by discharging moisture from the filtration chamber 9.

When the internal pressure of the diaphragm chambers 12 and 12a decreases to 1.4 MPa with the progress of the 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 to 1. Increase the pressure to 5 MPa.
Water pressing is performed by repeating this operation a plurality of times.

After the ON / OFF operation of the pressure water pump 17 is repeated 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, whereby the diaphragm chambers 12 and 12a are closed. The internal pressure is adjusted so as to be within a certain range, and the operation time of the pressure water pump 17 at the time of press dewatering is reduced.
When a predetermined filtrate discharge amount is detected, the water pressing step S3 ends.

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

Dewatering cake discharge process (S5)
The tightening cylinder 7 contracts to open the filter plate 4 and the diaphragm filter plate 5, and the dewatered cake formed in the filtration chamber 9 is discharged outside the machine. When continuously operating the filter press, 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 compression step S2, a large amount of compressed air is supplied to the diaphragm chambers 12, 12a of the pressure chamber 13, so that the diaphragm chambers 12, 12a are used as pressure tanks. In the air pressing step S2, air pressing is continued until the thickness of the dewatered cake becomes, for example, 1/3 of the width of the filtration chamber 9, and compressed air having a capacity of 2/3 of the width of the filtration chamber 9 is supplied to the diaphragm chamber 12. ing. Therefore, compressed air can be retained without separately providing a large-capacity pressure tank.

Therefore, in the water pressing step S3, the internal pressure of the diaphragm chambers 12 and 12a gradually decreases in accordance with the discharge of the filtrate, and the frequency of activation of the pressure water pump 17 to maintain the internal pressure of the diaphragm chambers 12 and 12a constant. Start-up time can be significantly reduced.

4 Filter Plate 5 Diaphragm Filter Plate 5a Diaphragm 6 Pressure Filter Plate 6a Diaphragm 9 Filtration Chamber 12 Diaphragm Chamber 12a Diaphragm Chamber 14 Pressure Water Supply Pipe 15 Compressed Air Pipe 21 Compressed Air Valve 22 Discharge Pipe 23 Flow Meter 24 Control Board 26 Stock Solution Supply Pipe S1 Press-in process S2 Air press process S3 Water press process

Claims (8)

A press-in step (S1) in which the undiluted solution is pressed into a filtration chamber (9) formed by a large number of filter plates (4) and a diaphragm filter plate (5) to produce a dewatered cake;
An air compression step (S2) of supplying compressed air to a diaphragm chamber (12) formed in the filtration chamber (9);
A water press step (S3) of supplying pressurized water to the diaphragm chamber (12) after the air press step (S2).
The air pressing step (S2) is continued until the thickness of the dewatered cake generated in the filtration chamber (9) by the expansion of the diaphragm (5a) becomes 1/4 to 2/3 of the thickness of the filtration chamber (9). A method for operating a filter press, comprising: Any one or more of the diaphragm filter plates (5) is a pressure filter plate (6),
The method for operating a filter press according to claim 1 or 2, wherein the undiluted solution is not pressed into the filtration chamber (9) formed by the pressure filter plate (6) in the pressing step (S1). The filter press according to claim 2, 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). Driving method. The thickness of the dewatered cake is calculated based on the flow rate of the filtrate discharged from the filtration chamber (9), the concentration of the stock solution, and the supply amount of the stock solution, according to any one of claims 1 to 3, wherein Operating method of the filter press described. In a filter press in which a stock solution is pressed into a filtration chamber (9) formed by a number of filter plates (4) and a diaphragm filter plate (5) to produce a dewatered cake,
At least one of the diaphragm filter plates (5) is a pressure filter plate (6),
A compressed air pipe (15) for supplying compressed air to a diaphragm chamber (12, 12a) formed in the diaphragm filter plate (5) and the pressure filter plate (6), and a pressure water supply pipe (14) for supplying pressurized water. Connect and
A pressure tank integrated filter press, characterized in that a stock solution supply pipe (26) is communicated only with a filtration chamber (9) formed between a filter plate (4) and a diaphragm filter plate (5). 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 other diaphragm filter plates (5). Item 6. A filter press integrated with a pressure tank according to Item 5. A discharge pipe (22) for discharging a filtrate from the filtration chamber (9) is provided with a flow meter (23),
The thickness of the dehydrated cake in the filtration chamber (9) is calculated based on the filtrate flow rate measured by the flow meter (23),
When the thickness of the dewatered cake is 1/4 to 2/3 of the thickness of the filtration chamber (9),
A control panel (24) for switching between a compressed air valve (21) of a compressed air pipe (15) and a pressure water valve (21) of a pressure water supply pipe (14);
The pressure press integrated with a pressure tank according to claim 5 or 6, further comprising: The pressure filter plate (6) is disposed at one end of the filter plate (4) and one end of the diaphragm filter plate (5), and the diaphragm (6a) stretched over the pressure filter plate (6) is a thin film rubber. The filter press integrated with a pressure tank according to any one of claims 5 to 7.

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