JPH0326083B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method and device for preventing deformation of a filter plate in a filter press having a built-in diaphragm for squeezing a cake formed in a filter chamber. be.

[Prior art]

Generally, as shown in FIG. 1, a filter plate 1 of a filter press with a built-in diaphragm includes a plurality of filter plates 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, . Recesses 1a, 1a for forming filter chambers are formed on each surface, and filter cloths 2, 2 are arranged on the surface of each filter plate 1, so that when the filter plates 1, 1... are brought into close contact, they are adjacent to each other. When slurry is supplied into a filter chamber 3 surrounded by a pair of filter cloths 2, 2 between each filter plate 1, 1, it is not only filtered, but also distributed within each filter chamber 3. A diaphragm 4 is installed between one of the two filter cloths 2, 2 and the surface of the filter plate 1 behind it, and the diaphragm 4 and the recess on the surface of the filter plate 1 are When the squeezed liquid is forced into the diaphragm chamber 5 formed between the filter chamber 1a and the filter chamber 3, the cake (not shown) in the filter chamber 3 is squeezed.

By the way, in the case of such a filter press with a built-in diaphragm, in order to make the filter chamber 3 as large as possible and to reduce the weight of the filter plate 1 as much as possible, a pair of recesses 1a, 1a are formed on both sides of the filter plate 1. The core part of the filter plate 1, that is, the core plate 1b
It is required to make the thickness as thin as possible.

However, when the slurry is supplied to each of the filter chambers 3, 3, etc., if foreign matter is present in the slurry and it blocks only the supply ports to some of the filter chambers 3, the filter A state occurs in which the slurry supply pump pressure does not act only on chamber 3, and the slurry pressure in the adjacent filter chamber 3 across core plate 1b acts as a differential pressure that deforms (bends) core plate 1b. A situation arises that acts.

As a means for preventing the deformation of the core plate 1b, that is, the deformation of the filter plate 1 when such a differential pressure occurs, for example, Japanese Patent Publication No. 55-32405 discloses that A pressure control valve (not shown) is provided in the liquid flow path 6 to control the pressure of the squeezed liquid supplied into the flow path 6 to be lower than the slurry pressure, and during the slurry supply into the filter chamber 3, A condition is created in which squeezed liquid controlled to be lower than the slurry pressure can be injected into the diaphragm chamber 5 at any time, and if a problem occurs in the slurry supply circuit and the slurry pressure in some of the filter chambers 3 decreases, , the squeezed liquid in this channel 6 is immediately and automatically transferred to the diaphragm chamber 5 so as to cancel out the deformation of the filter plate 1 caused by the pressure difference between the filter chambers 3 and 3 located on both sides of the filter plate 1. It has been proposed to allow the water to flow into the core plate 1b of the filter plate 1 and pressurize the core plate 1b of the filter plate 1.

[Problem that the invention seeks to solve]

That is, in the method for preventing deformation of a filter plate disclosed in the above-mentioned Japanese Patent Publication No. 55-32405, the pump pressure of the squeezing liquid for squeezing the cake is much higher (about 3 times) than the press-in pressure of the slurry. Therefore, if this squeezed liquid is allowed to act on the diaphragm chamber 5 while connected to the pump circuit, the filter chamber 3
Since a situation arises in which it is impossible to press slurry at a lower pressure into the pump, the pump pressure of the squeezed liquid higher than the slurry pressure can be adjusted using a differential pressure control valve, that is, an eye loader valve piloted by the difference in pump pressure of the slurry. The pressure is controlled so that it is lower than the slurry pressure by letting it escape into the tank circuit, and then it is connected to the flow path 6 communicating with the diaphragm chamber 5 while the slurry is being supplied into the filter chamber 3. However, with this method, the compressed liquid injection pump must be kept in operation and unloaded at all times while the slurry is being pressurized into the filter chamber 3. , it is not possible to maintain the squeezed liquid controlled to a desired high pressure lower than the slurry pressure in a state where it can be press-injected into the diaphragm chamber 5 at any time.

This invention enables the pressurized liquid pump to be connected to the flow path 6 passing through the diaphragm chamber 5 during filtration without having to operate the pressurized liquid pump at all times while the slurry is being pressurized into the filter chamber 3. A new method and implementation of the method that can prevent deformation of the filter plate by constantly generating pressure of the same strength as the slurry pressure in the diaphragm chamber 5 even if the diaphragm chamber 5 is not in communication with the slurry pressure. The goal is to provide equipment for

[Means for solving problems]

That is, in order to solve the above-mentioned problem, the first invention, in the diaphragm built-in filter press as described above, presses slurry into the filter chamber 3 with an appropriate amount of squeezed liquid in the diaphragm chamber 5, By extracting a small amount of the squeezed liquid in the diaphragm chamber 5 and filtering the slurry press-filled into the filtration chamber 3, during that time, the squeezed liquid present in the squeezed liquid flow path 6 leading to the diaphragm chamber 5 is removed. pressure,
A second invention resides in a method for preventing deformation of a filter plate in a filter press with a built-in diaphragm, which is characterized by balancing the supply pressure of slurry into the filtration chamber 3 and keeping it the same. The amount of squeezed liquid discharged from the diaphragm chamber 5 while the slurry is being forced into the filtration chamber 3 is adjusted to the extent that all the squeezed liquid in the diaphragm chamber 5 does not escape during slurry supply to the flowing squeezed liquid flow path 6. A filter press with a built-in diaphragm is characterized in that it is connected to a bypass drainage circuit in which a flow rate control valve is inserted, which allows the flow rate to be reduced to a small amount.

[Effect]

In the method for preventing deformation of a filter plate according to the first invention, slurry is press-fitted into the filter chamber 3 while an appropriate amount of squeezed liquid is placed in the diaphragm chamber 5. If the amount of squeezed liquid is appropriately set so that it does not reach a value close to the maximum volume of the diaphragm chamber 5, even if an appropriate amount of squeezed liquid exists in the diaphragm chamber 5, it will not reach the filtration chamber 3. In the method of the present invention, as the filtration operation progresses, the squeezed liquid in the diaphragm chamber 5 is drawn out in small amounts, so that the filtration operation in which cake accumulates in the filtration chamber 3 is avoided. As the end of the process approaches, the amount of squeezed liquid present in the pressurized chamber 5 gradually decreases and the volume of the filter chamber 3 gradually increases. There is no obstacle to supplying the slurry into 3 and filtering it. During that time, the pressure of the squeezed liquid existing in each diaphragm chamber 5 is always balanced with the slurry pressure in the filter chamber 3 where the diaphragm 4 and the filter cloth 2 are in contact with each other at a distance, and the pressure is always equal between each diaphragm chamber 5. Since they are also connected through the flow path 6, when performing a filtration operation in this manner, the diaphragm chamber 5 or filter chamber 3 that is in constant contact with both sides of the core plate 1b of each filter plate 1 is The same hydraulic pressure will be applied.

In the filter press according to the present invention, in particular, a diaphragm chamber is provided in a flow path 6 for the squeezed liquid leading to the diaphragm chamber 5, apart from the usual circuit for discharging the squeezed liquid from the flow path 6. 5 is connected to a bypass circuit in which a flow rate control valve that can control the amount of squeezed liquid discharged is inserted, so when the amount of discharged from the diaphragm chamber 5 is set appropriately using this flow rate control valve, the amount of squeezed liquid flowing into the filtration chamber 3 is The amount of squeezed liquid extracted from the diaphragm chamber 5 can be controlled so that the squeezed liquid in the diaphragm chamber 5 does not escape while the slurry is being supplied.

〔Example〕

An embodiment of the present invention will be explained from the second aspect of the invention regarding the device.As shown in FIG. and a supply circuit 9 into which the switching valve 8 can be inserted, and the switching valve 1
In the filter press according to the present invention, a drain circuit 11 into which a filter 0 can be inserted is connected to the squeezed liquid flow path 6 leading to the diaphragm chamber 5. A variable type that can adjust the amount of squeezed liquid discharged from the diaphragm chamber 5 during slurry press-in to a small amount that prevents all of the squeezed liquid once put into the diaphragm chamber 6 from escaping during slurry press-in. Flow rate adjustment valve 12
A bypass drain circuit 14 in which a switching valve 13 and a switching valve 13 are inserted in series is connected to a drain circuit 11 for the squeezed liquid from the flow path 6.
It is connected separately.

In addition, in FIG. 1, 15 is a slurry supply circuit to the filter chamber 3 into which a slurry supply pump 16 and a switching valve 17 are inserted.

Therefore, according to the filter press according to the second invention, the first invention can be implemented as follows.

That is, when supplying slurry to each empty filter chamber 3 and starting slurry filtration operation, each switching valve 10 of the drain circuit 11, 14 from the flow path 6 communicating with the diaphragm chamber 5, 13 is closed, the on-off valve 8 of the liquid supply circuit 9 communicating with the flow path 6 is connected to the slurry supply circuit 15 to each filter chamber 3.
When the switching valve 17 inserted in 20-40
By controlling the time in seconds,
An appropriate amount (for example, 1/4 to 1/2 of the maximum volume) of the squeezing fluid can be forced into the diaphragm chamber 5. Because,
This is because the pump pressure for feeding the squeezed liquid is stronger than the pump pressure for feeding the slurry.

In this way, even if the diaphragm chamber 5 is pressurized with an appropriate amount of squeezed liquid, the slurry supplied to the filtration chamber 3 during that period is not equal to the amount of squeezed liquid pressurized into the diaphragm chamber 5. Therefore, unless the squeezed liquid is forced into the diaphragm chamber 5 until the diaphragm chamber 5 reaches its maximum volume, the slurry supplied into the filter chamber 3 will be
Similar to the conventional method in which the squeezed liquid is not forced into the diaphragm chamber 5, it is smoothly filtered.

During this time, since the volume of the diaphragm chamber 5 is variable, the pressure of the squeezed liquid pressurized into the diaphragm chamber 5 is balanced with the pressure of the slurry supplied to the filtration chamber 3 and kept the same. The pressure rises as the pressure of the slurry in the filter chamber 3 increases, but this balanced relationship continues even if the injection of squeezed liquid is stopped, and even if a small amount of squeezed liquid leaks, the diaphragm This continues as long as the squeezed liquid remains in the chamber 5.

The first invention utilizes such a phenomenon, and once a suitable amount of squeezed liquid is pressurized into the diaphragm chamber 5, the squeezed liquid in the diaphragm chamber 5 temporarily In order to smoothly filter the slurry by gradually recovering the narrowed volume of the filter chamber 3 and supplying slurry to the filter chamber 3, the switching valve 1 of the bypass drain circuit 14 is operated.
3 is opened to remove a small amount of the squeezed liquid from the diaphragm chamber 5, while filtering the slurry that is subsequently press-fitted into the filtration chamber 3.

By doing this, on the one hand, the volume of the filter chamber 3 gradually increases, so that the slurry supplied into the filter chamber 3 can be smoothly filtered to the end as in the conventional method, and on the other hand, While supplying slurry, the trouble mentioned above occurred and some of the filter chambers 3
If a situation arises in which the slurry supply pump pressure does not directly act only on the filtration chamber 3, the diaphragm chamber 5 in which the diaphragm 4 is in contact with the filter chamber 3 is immediately and automatically As the squeezed liquid moves through the flow path 6, the slurry supply pump pressure is indirectly applied to the filter chamber 3, so that there is no pressure difference between the filter chambers 3 on both sides of the filter plate 1. This can be prevented from occurring.

The above-mentioned filtration operation, that is, the operation of withdrawing the squeezed liquid from the diaphragm chamber in small amounts according to the first invention, is performed by intermittently short-term operation of the switching valve 10 inserted into the known liquid drainage circuit 11. Although this may be done by opening the diaphragm, the bypass circuit 14 according to the second aspect of the invention can easily control the amount of squeezed liquid to be extracted to an optimum amount and drain the squeezed liquid in the diaphragm chamber 5. It can be removed gradually.

In addition, in the above embodiment, by starting the pressurized liquid into the diaphragm chamber 5 at the same time as the supply of slurry to the filtration chamber 3 is started, an appropriate amount of pressurized liquid in the diaphragm chamber 5 is once pressurized after the start of the filtration operation. However, in other embodiments, the filter chamber 3
Prior to the start of supply of slurry to the diaphragm chamber 5, the pressurized liquid is started to be pressurized into the diaphragm chamber 5, and an appropriate amount of pressurized liquid is pressurized into the diaphragm chamber 5 before or after the start of the filtration operation. Alternatively, a state may be formed.

Further, in the above embodiment, an example is shown in which the variable flow rate regulating valve 12 is used as the flow rate control valve inserted into the bypass drain circuit 14, but in other embodiments, this may be a fixed type. It may be replaced with a flow rate regulating valve.

〔effect〕

As explained above, when the filtration operation is performed by the method of the first invention, the squeezed liquid pressurized into the diaphragm chamber 5 is balanced with the slurry pressure in the filtration chamber 3 during the filtration operation, as described above. Since the liquid pressure in all the filter chambers 3 and all the diaphragm chambers 5 is maintained at the same pressure, the core plate 1b of each filter plate 1 has no pressure at all. Differential pressure does not work. Therefore, no deformation occurs in the filter plate.

Furthermore, in the method of the present invention, at the beginning of each filtration operation, slurry is supplied into the filtration chamber 3 with an appropriate amount of squeezed liquid placed in the diaphragm chamber 5. As the volume of the filter chamber 3 is narrowed by
The slurry is filled in the filter chamber 3, and the slurry pressure builds up in the filter chamber 3 earlier, which has the effect of hastening the start of the actual filtration operation.

In the filter press of the second invention, a bypass drain circuit is connected to the flow path 6 leading to the diaphragm chamber 5, in which a flow control valve that can control the amount of squeezed liquid discharged from the diaphragm chamber 5 is inserted. Therefore, the amount of squeezed liquid extracted from the diaphragm chamber 5 during slurry supply into the filter chamber 3 can be easily controlled, and the direction of the first invention can be easily carried out.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a main part of a filter press with a built-in diaphragm according to the present invention and a hydraulic circuit connected thereto. 1...filter plate, 1a...recess, 1b...core plate, 2
... Filter cloth, 3 ... Filter chamber, 4 ... Diaphragm, 5
. . . diaphragm chamber, 6 .

Claims (1)

[Scope of Claims] 1. A recess for forming a filter chamber is formed on the surface of each of a plurality of filter plates that are supported so as to be able to freely approach and separate from each other, and a filter cloth is arranged on the surface of each filter plate, so that the filter plate is When slurry is supplied into a filter chamber surrounded by filter cloths between adjacent filter plates when the slurry is in close contact with each other, the slurry is filtered. A diaphragm is installed between the chamber and the surface of the filter plate on one side, and when the squeezed liquid is forced into the diaphragm chamber formed between the diaphragm and the recess on the surface of the filter plate, the cake in the filter chamber is removed. In a filter press with a built-in diaphragm that is configured to be compressed, slurry is supplied to the filter chamber with an appropriate amount of squeezed liquid in the diaphragm chamber, and a small amount of the squeezed liquid in the diaphragm chamber is drawn out. By filtering the slurry press-fitted into the filter chamber, the pressure of the squeezed liquid existing in the flow path of the squeezed liquid leading to the diaphragm chamber is maintained at the same level as the supply pressure of the slurry into the filter chamber. Features: A method for preventing deformation of a filter plate in a filter press. 2. A state in which an appropriate amount of pressed liquid is placed in the diaphragm chamber is achieved by injecting pressed liquid at a higher pressure than the slurry for a predetermined time at the same time as the slurry starts being pressurized into the filtration chamber. The method described in. 3. Prior to starting to pressurize the slurry into the filter chamber,
2. The method according to claim 1, wherein the diaphragm chamber is filled with an appropriate amount of squeezed liquid by starting to pressurize the squeezed liquid into the diaphragm chamber. 4 A concave portion for forming a filter chamber is formed on the surface of each of a plurality of filter plates that are supported so as to be able to freely approach and separate from each other, and a filter cloth is arranged on the surface of each filter plate, so that when the filter plates are brought into close contact with each other, each of the adjacent filter plates is A filter chamber surrounded by filter cloth is formed between the filter plates, and a diaphragm is installed between the filter chamber surrounded by two filter cloths between each filter plate and the surface of the filter plate on one side thereof. , a diaphragm chamber is formed between this diaphragm and the recess on the surface of the filter plate;
A filter press with a built-in diaphragm, in which a bypass drain circuit in which a flow control valve for discharging a small amount of squeezed liquid from the diaphragm chamber is inserted is connected to the squeezed liquid flow path leading to the diaphragm chamber. A filter press with a built-in diaphragm.