JP2023022949A - Operation method of filter press - Google Patents

Abstract

To provide an operation method of a filter press where a stock solution is fed into a filtration chamber in a state that a diaphragm is shrunk on the diaphragm stretch surface of a filter plate.SOLUTION: An operation method of a filter press includes: a press-in step S1 to press-in a stock solution into a filtration chamber 9 formed with a lot of filter plates 4; a compression step S2 to feed a compression fluid into a diaphragm chamber 13 formed in the filtration chamber 9; a dehydrated cake discharge step S3 to discharge a cake in the filtration chamber 9 by opening the filter plates 4; and a diaphragm shrinkage step S4 to shrink a diaphragm 8 on the diaphragm stretch surface 12 of the filter plates 4. The volume of the filtration chamber in the press-in step can be maximized by starting the press-in step S1 after starting the diaphragm shrinkage step S4. The volume of the stock solution to be treated can be increased and the thickness and water content of a formed dehydrated cake are stabilized.SELECTED DRAWING: Figure 6

Description

TECHNICAL FIELD The present invention relates to a method of operating a filter press having a filter plate with a diaphragm stretched thereon, and relates to a method of operating a filter press in which a raw solution is supplied to a filtration chamber in a state in which the diaphragm is shrunk onto the diaphragm-stranded surface of the filter plate.

Conventionally, a filter that supplies a compressed fluid to a diaphragm chamber formed by a diaphragm stretched on a filter plate and a diaphragm stretched surface of the filter plate, expands the diaphragm, and compresses the undiluted solution supplied to the filtration chamber. Press is known. Such a filter press opens a valve communicating with the diaphragm chamber after the end of squeezing, and discharges the compressed fluid in the diaphragm chamber. As the pressurized fluid is discharged, the pressure in the diaphragm chamber is reduced to normal pressure, causing the diaphragm to contract.

At this time, some of the compressed fluid is not discharged and remains in the lower part of the diaphragm chamber, or the pressure in the diaphragm chamber is unevenly reduced. was there. If the stock solution is supplied to the filtration chamber in this state, the amount of stock solution that can be supplied to the filtration chamber will decrease by the expansion volume of the diaphragm, and the inflow resistance of the stock solution will increase at the expansion part of the diaphragm, and the cake moisture content in the filtration chamber will increase. was not stable.

Patent Literature 1 discloses a filter press having a pump for sucking pressurized water from a diaphragm chamber.

Japanese Utility Model Publication No. 55-042803

In Patent Document 1, the pressurized water filled in the diaphragm chamber is removed when the filter plate is opened to discharge the dehydrated cake, for the purpose of preventing obstacles to running of the filter cloth due to swelling of the diaphragm and shortening the water removal time (miscellaneous time). It is extracted. It is not intended to extract the compressed water remaining in the diaphragm for the purpose of efficiently supplying the stock solution into the filtration chamber. In addition, a negative pressure acts on the diaphragm chamber that is contracted by being sucked by the pump. Outside air may enter the diaphragm chamber and cause the diaphragm to expand toward the filtration chamber. However, Patent Literature 1 does not include a description of maintaining a state in which compressed water is extracted from the diaphragm chamber.

The present invention provides a raw solution supply method for a filter press, in which the raw solution is supplied to a filtration chamber in a state in which the diaphragm is contracted on the diaphragm-mounted surface of the filter plate.

A press-fitting step of press-fitting the undiluted liquid into the filtration chamber formed by a large number of filter plates, a compression step of supplying the compressed fluid to the diaphragm chamber formed in the filtration chamber, and opening the filter plate to discharge the cake in the filtration chamber. A filter press operating method comprising a step of discharging a dehydrated cake, comprising a diaphragm shrinking step of shrinking the diaphragm onto the diaphragm-stretched surface of the filter plate, and starting the press-fitting step after the start of the diaphragm shrinking step, whereby the diaphragm is The undiluted solution can be supplied in a state in which the is contracted on the diaphragm stretched surface.

In the diaphragm contraction step, the compressed fluid in the diaphragm chamber is sucked by a suction pump, and when a predetermined contraction condition is satisfied, the compressed fluid pipe communicating with the diaphragm chamber is closed to maintain the contracted state of the diaphragm. Since the diaphragm chamber is maintained in a state of negative pressure, the diaphragm does not expand toward the filtering chamber during the press-fitting process.

By continuing suction with the suction pump until a predetermined time elapses or until a predetermined pressure is reached, the diaphragm can be contracted to the diaphragm mounting surface, and the volume of the filtration chamber can be reduced. maximum can be ensured.

In the diaphragm contraction step, the suction pump is driven to suck the compressed fluid from the diaphragm chamber, and the suction pump is stopped to end the suction of the compressed fluid from the start to the end of the press-fitting step. The contracted state of the diaphragm can be maintained only by operation.

According to the present invention, the volume of the filtration chamber can be maximized by shrinking the entire surface of the diaphragm, so that the stock solution can be efficiently supplied. In addition, since the bulge of the diaphragm toward the filter chamber side, which causes inflow resistance when supplying the stock solution, can be wiped out, uniform press-fitting into the filter chamber can be performed, and the thickness of the dehydrated cake and the moisture content of the dehydrated cake are stabilized.

It is a flow diagram of a filter press according to the present invention. Similarly, it is a partial longitudinal perspective view of the parallel filter plate. Similarly, it is a partial conceptual diagram of a filter chamber formed by closing parallel filter plates. Similarly, it is a partial conceptual diagram of the filter chamber at the time of the pressing process. Similarly, it is a partial conceptual diagram of the filtration chamber at the time of the dehydrated cake discharge process. Similarly, it is a partial conceptual diagram of the filtration chamber during the diaphragm contraction process.

FIG. 1 is a flow diagram of a filter press according to the 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 large number of filter plates 4 are supported on the guide rails 3 and arranged in parallel. A clamping cylinder 5 arranged on the rear frame 2 is connected to the movable head 6, and the clamping cylinder 5 opens and closes the filter plates 4 arranged side by side.

FIG. 2 is a partial longitudinal perspective view of filter plates arranged in parallel.
A pair of filter cloths 8 are suspended in a filter chamber 7 formed by the filter plates 4 facing each other, and the stock solution is pressurized between the filter cloths 8 from an upper supply port 9 penetrating the filter plates 4 . An expandable and contractible diaphragm 12 is stretched on the diaphragm stretched surface 11 of the filter plate 4 facing the filter bed 10 . A diaphragm chamber 13 is formed between the diaphragm 12 and the diaphragm extending surface 11 , and is configured to be able to supply compressed fluid to the diaphragm chamber 13 from the outside through compressed fluid holes 14 . By supplying a pressurized fluid and expanding the diaphragm 12 toward the filter chamber 7 side, the undiluted liquid supplied to the filter chamber 7 is compressed, and solid-liquid separation is performed by the filter cloth 8 . The liquid that has passed through the filter cloth 8 is discharged to the outside through the filtrate passage 15 formed below.

FIG. 3 is a partial conceptual diagram of a filtration chamber formed by closing parallel filter plates.
In this embodiment, the filter plate 4 with the filter bed 10 formed on both sides and the filter plate 4 with the diaphragm 12 stretched on both sides are alternately arranged in parallel, and only the filter plate 4 with the diaphragm 12 stretched is filled with the compressed fluid. A hole 14 is formed. A compressed fluid pipe 16 is communicated with the compressed fluid hole 14 to supply the compressed fluid to the diaphragm chamber 13 from a supply source (not shown). In addition, the filter plate 4 with the filter bed 10 formed on one side and the diaphragm 12 stretched on the other side may be arranged side by side.

The pressurized fluid holes 14 may communicate independently with the diaphragm chambers 13 formed on the front and back of the filter plate 4, or may communicate with the diaphragm chambers 13 in common. In either case, each pressurized fluid hole 14 is joined by a pressurized fluid tube 16 .

As shown in FIG. 1, the compressed fluid line 16 is provided with a supply pump 17 via valve V1 and a suction pump 18 via valve V2. The supply pump 17 supplies the compressed fluid pulled up from the water supply tank 19 to the diaphragm chamber 13 , and the suction pump 18 returns the compressed fluid extracted from the diaphragm chamber 13 to the water supply tank 19 .

The compressed fluid used in this embodiment may be liquid (eg, water) or gas, and is not particularly limited. When gas is used, a known air tank or the like is provided instead of the water supply tank 19 .

When expanding the diaphragm 12, the supply pump 17 is operated with the valve V2 closed and the valve V1 opened. By operating the supply pump 17 , the compressed fluid in the water supply tank 19 is transferred to the compressed fluid pipe 16 and the compressed fluid hole 14 in this order, and supplied to each diaphragm chamber 13 .

When contracting the diaphragm 12, the suction pump 18 is operated with the valve V1 closed and the valve V2 opened. By operating the suction pump 18 , the compressed fluid in each diaphragm chamber 13 is sucked through the compressed fluid hole 14 and returned to the water supply tank 19 through the compressed fluid pipe 16 . The contraction here means a state in which the diaphragm 12 is closer to the diaphragm mounting surface 11 side than when the diaphragm chamber 13 is at atmospheric pressure.

By closing the valve V2 and stopping the suction pump 18 in a state where the diaphragm 12 is contracted to the diaphragm tensioning surface 11, the contracted state of the diaphragm 12 can be maintained.

The contracted state of the diaphragm 12 may be maintained while the suction pump 18 continues to suck the compressed fluid from the diaphragm chamber 13 .

Alternatively, instead of sucking the diaphragm chamber 13 , a pressurized fluid may be supplied to the filtration chamber 7 through the filtrate passage 15 to pressurize the filtration chamber 7 , thereby contracting the diaphragm 12 .

<Compression step (S2)>
FIG. 4 is a partial conceptual diagram of the filtration chamber during the pressing process. After stopping the pressurization of the stock solution, the supply pump 17 is driven to open the valve V1 and close the valve V2 to supply the compressed fluid to the diaphragm chamber 13 . As the pressurized fluid continues to be supplied, the diaphragm chamber 13 expands toward the filter chamber 7 and the dehydrated cake formed in the filter chamber 7 is compressed. As the dehydrated cake is compressed, more filtrate is discharged from the dehydrated cake and dehydration proceeds. When the supply of the compressed fluid is continued and a predetermined time has passed, the supply pump 17 is stopped and the valve V1 is closed to end the compression step S2.

<Dehydrated cake discharge step (S3)>
FIG. 5 is a partial conceptual diagram of the filtration chamber during the dehydrated cake discharging process. After the pressing step S2 is completed, the clamping cylinder 5 is contracted to open the filter plate 4, and the dehydrated cake formed in the filter chamber 7 is discharged out of the machine. Simultaneously with the plate opening, the valve V2 is opened to return the compressed fluid in the diaphragm chamber 13 to the water supply tank 19.

At this time, the diaphragm chamber 13 is decompressed to normal pressure, and the diaphragm 12 is in a state in which the lower portion is inflated by the compressed fluid remaining in the lower portion of the diaphragm chamber 13, or an unbalanced load is applied during contraction, and a portion of the diaphragm 12 is on the side of the filtration chamber 7. It may become inflated. Therefore, in the present invention, a diaphragm contraction step S4 is performed to contract the diaphragm 12. FIG.

<Diaphragm Contraction Step (S4)>
FIG. 6 is a partial conceptual diagram of the filtration chamber during the diaphragm contraction process. After the dehydrated cake discharge step S3 is completed, the valve V1 is closed, the valve V2 is opened, and the suction pump 18 is driven to suck the pressurized fluid in the diaphragm chamber 13 . The pressurized fluid is returned to the water supply sump 19 via the pressurized fluid line 16 . At the same time, the outside air entering the diaphragm chamber 13 when the valve V2 is opened in the dehydrated cake discharge step S3 is also sucked. As the air is sucked by the suction pump 18, the inside of the diaphragm chamber 13 is brought into a negative pressure state, and the diaphragm 12 is contracted to the diaphragm mounting surface 11 as shown in FIG.

The compressed fluid in the diaphragm chamber 13 is sucked by the suction pump 18, and when predetermined contraction conditions such as the lapse of a predetermined time and the predetermined pressure of the diaphragm chamber 13 are satisfied, the valve V2 is closed to communicate with the diaphragm chamber 13. The squeeze fluid line 16 is closed and the suction pump 18 is stopped. Since the diaphragm chamber 13 is maintained in a negative pressure state, the contracted state of the diaphragm 12 can be maintained while the valve V2 is closed. Since the maximum volume of the filtration chamber can be secured by contracting the diaphragm 12 to the diaphragm mounting surface 11, it is desirable to satisfy the contraction condition at the start of the press-fitting step S1, but after the start of the press-fitting step S1. may be set so as to satisfy the shrinkage condition.

Alternatively, instead of closing the valve V2, the contracted state of the diaphragm 12 may be maintained by continuing the suction with the suction pump 18. FIG. In that case, the suction pump stops between the start and end of the press-fitting step S1.

In this embodiment, the diaphragm contracting step S4 is performed after the dehydrated cake discharging step S3, but it may be started between the end of the pressing step S2 and the start of the pressing step S1. S4 may be started. In this case, it is not necessary to set the diaphragm 12 to normal pressure in the dehydrated cake discharge step S3 to discharge the compressed fluid. Air does not enter the diaphragm chamber 13 by always closing V2.

<Press-fitting step (S1)>
With the diaphragm 12 contracted to the diaphragm mounting surface 11, the press-fitting step S1 is started. The clamping cylinder 5 is driven to close the parallel filter plates 4 to form the filter chamber 7 . The undiluted liquid is pressurized into each of the filtration chambers 7 from the undiluted liquid press-in pump 20 through the supply port 9 to perform filtration. The filter cloth 8 stretched in the filtration chamber 7 separates the filtrate from the raw liquid to form a dehydrated cake, and the filtrate is discharged out of the filtration chamber 7 through the filtrate passage 15 .

Since the entire surface of the diaphragm 12 is contracted and the capacity of the filtration chamber 7 is maximized, the throughput of the stock solution is increased. Moreover, since there is no convex portion formed from the diaphragm 12 toward the filter chamber 7 side, no inflow resistance is generated in the undiluted solution to be supplied. Since the undiluted solution can be stably supplied to the filtration chamber 7, uniform press-fitting can be performed into the filtration chamber 7, and the thickness and water content of the dehydrated cake to be produced are stabilized.

At the end of the press-fitting step S1, the valve V1 or the valve V2 is opened to normalize the pressure in the diaphragm chamber 13, thereby ending the diaphragm contraction step S4. It should be noted that the press-fitting step S1 may end after a predetermined time has elapsed since the start of the press-fitting step S1.

In addition, in this embodiment, the supply pump 17 and the suction pump 18 are integrated into the compressed fluid pipe 16 and communicated with the diaphragm chamber 13, but separate pipes may be provided.

In the operating method of the filter press according to the present invention, the raw liquid can be supplied with the filtration chamber having the maximum capacity by supplying the raw liquid with the diaphragm contracted, so that the processing amount of the raw liquid increases. Since no protrusion is formed from the diaphragm toward the filtration chamber side, a dehydrated cake having a constant thickness can be produced and the moisture content of the cake is also constant.
Any filter press having a filter plate on which a diaphragm is stretched can be used, and existing pipes and the like can be used.

4 Filter plate 8 Diaphragm 9 Filtration chamber 12 Diaphragm tension surface 13 Diaphragm chamber 16 Compressed fluid tube 18 Suction pump S1 Press-in process S2 Compression process S3 Dewatered cake discharge process S4 Diaphragm contraction process

Claims (5)

A press-fitting step (S1) of press-fitting the undiluted solution into a filtration chamber (9) formed by a large number of filter plates (4);
A compression step (S2) of supplying a compressed fluid to the diaphragm chamber (13) formed in the filtration chamber (9);
A dehydrated cake discharge step (S3) of opening the filter plate (4) and discharging the cake in the filtration chamber (9);
In a method of operating a filter press comprising
A diaphragm shrinking step (S4) for shrinking the diaphragm (8) to the diaphragm mounting surface (12) of the filter plate (4),
After starting the diaphragm contraction step (S4),
A method for operating a filter press, characterized by starting a press-fitting step (S1). The diaphragm contraction step (S4) includes
The compressed fluid in the diaphragm chamber (13) is sucked by the suction pump (18),
When the predetermined shrinkage conditions are met,
2. The method of operating a filter press according to claim 1, wherein the compressed fluid pipe (16) communicating with the diaphragm chamber (13) is closed to maintain the contracted state of the diaphragm (8). 3. The method of operating a filter press according to claim 2, wherein the suction pump (18) continues to suction until a predetermined time elapses. 3. The method of operating a filter press according to claim 2, wherein the suction pump (18) continues suction until the diaphragm chamber (13) reaches a predetermined pressure. The diaphragm contraction step (S4) includes
driving the suction pump (18) to suck the compressed fluid from the diaphragm chamber (13);
Between the start and end of the press-fitting step (S1),
2. A method of operating a filter press according to claim 1, characterized in that the suction pump (18) is stopped to terminate the suction of pressurized fluid.

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