JP5354466B2 - Stock solution filtration device and method - Google Patents

Description

  The present invention relates to an apparatus and a method for filtering a stock solution that does not reach the volume in a leaf filter.

  FIG. 1 is a schematic diagram of a conventional leaf filter. The leaf filter uses a disk-shaped filter element 1 (referred to as a filter leaf or a filter disk) having a filtration surface on its surface, fills the tank with the stock solution, and cakes solids in the stock solution on the surface of the filter element 1 This is a solid-liquid separator that is formed as a layer 2 and separates the stock solution 3 into a solid 4 (cake) and a filtrate 5 by the cake layer 2.

Leaf filters are roughly classified into a type that discharges cake as a solid (dry cake) and a type that discharges cake as a slurry.
In the leaf filter , an assembly of the filter elements 1, that is, a plurality of filter elements 1 fixed to a vertical hollow rotating shaft (filter shaft 6) is called a filter nest 7. Various methods such as rotation, vibration, scraping, and backwashing are used to discharge the cake. In the example of the figure, the filter nest 7 is provided with a rotation driving device 8, and after the solid-liquid separation is completed, the filter nest 7 is rotated at a high speed to move the cake layer 2 to the outside of the filter element 1 by centrifugal force. It discharges | emits from the discharge port 9a provided in the downward direction of the vessel 9, and complete | finishes one solid-liquid separation.

  Further, as described above, since the solid-liquid separation in the leaf filter is performed in a state where the tank is filled with the stock solution 3, the stock solution in the filter is filtered by gas pressurization after the stock solution supplied from the outside is exhausted. Then, with the progress, the filter element is exposed from the liquid surface, and the pressurized gas for pressurizing the stock solution passes through the exposed filter element, so that the stock solution below the liquid surface cannot be filtered.

  Therefore, in the leaf filter of FIG. 1, as shown in this figure, the filter element 1 is inclined inward to have a truncated conical shape. In this case, a residual liquid treatment means for overflowing (overflowing) from the outer peripheral portion onto the lower filter element while collecting the stock solution was taken. Therefore, in this residual liquid processing means, since the pressurized gas acts uniformly on the residual liquid on each filter element, all the filter elements can be used in the same manner during the residual liquid processing, and the processing capacity is almost the same during the residual liquid processing. There is an advantage that does not decrease.

  As another residual liquid processing means, for example, Patent Document 1 is disclosed.

Japanese Patent Application Laid-Open No. 2002-233714, “Leaf Filter and Remaining Liquid Treatment Method”

As described above, when the stock solution is filtered with the leaf filter, it is necessary to fill the inside of the tank with the stock solution and form the solid matter in the stock solution as the cake layer 2 on the surface of the filter element 1.
However, when the amount of the stock solution is small and does not reach the volume in the leaf filter, the tank cannot be filled with the stock solution, so that the solid matter in the stock solution cannot be formed on the surface of the filter element 1 as the cake layer 2. . In this case, even if the residual liquid is filtered by the above-mentioned residual liquid processing means, there is no cake layer 2 on the surface of the filter element 1, so that there is a problem that the filtrate becomes cloudy at first and satisfactory filtration cannot be performed. .

  The present invention has been developed to solve the above-described problems. That is, an object of the present invention is to provide a stock solution filtering apparatus and method that can prevent turbidity of the filtrate and perform satisfactory filtration even when the amount of the stock solution is less than the volume in the leaf filter.

According to the present invention, a stock solution tank that holds a stock solution, a leaf filter having a residual liquid filtration mechanism, a stock solution pump that pumps the stock solution, a filtrate tank that collects the filtrate filtered by the leaf filter,
A stock solution filtration line for supplying a stock solution from the stock solution tank to a leaf filter residual fluid filtration mechanism and filtering the residual solution;
A residual liquid filtration line for supplying a raw liquid from a lower part of the leaf filter to a residual liquid filtration mechanism of the leaf filter and filtering the residual liquid;
A filtrate recovery pipe having a filtrate recovery valve and recovering the filtrate from the leaf filter to the filtrate tank;
A filtrate circulation pipe that has a filtrate circulation valve and circulates the filtrate to the stock solution tank from between the leaf filter and the filtrate recovery valve;
An undiluted solution filtration apparatus is provided, wherein the undiluted solution filtration line and the remaining liquor filtration line are alternately switched in a state where the filtrate collection valve is closed and the filtrate circulation pipe is communicated.

According to an embodiment of the present invention, the stock solution filtration line includes a first stock solution supply pipe that has a first stock solution valve and supplies the stock solution from the stock solution tank to the suction port of the stock solution pump, and a second stock solution valve. A second stock solution supply pipe for supplying the stock solution from the discharge port of the stock solution pump to the residual liquid filtration mechanism of the leaf filter,
The residual liquid filtration line includes a second raw liquid supply pipe, a third raw liquid supply pipe having a third raw liquid valve, and supplying a raw liquid between the first raw liquid valve and the raw liquid pump from a lower portion of the leaf filter; Including

  In addition, a fourth stock solution valve having a fourth stock solution valve for supplying the stock solution to a lower portion of the leaf filter from between the stock solution pump and the second stock solution valve, and a pressurized gas valve is provided at the upper portion of the leaf filter. A pressurized gas pipe for supplying pressurized gas, and a gas vent pipe having a gas vent valve and communicating between the second raw liquid valve and the leaf filter and the raw liquid tank.

Further, according to the present invention, the stock solution is supplied from the stock solution tank to the residue filter filtration mechanism of the leaf filter, the residue solution is filtered, and the turbid residue solution that has passed through the leaf filter is collected in the stock solution tank. A liquid filtration circulation step;
A second residual liquid filtration / circulation step of supplying a raw liquid from the lower part of the leaf filter to the residual liquid filtration mechanism of the leaf filter, filtering the residual liquid, and collecting the turbid residual liquid that has passed through the leaf filter in the raw liquid tank And
There is provided a raw solution filtration method, wherein the first residual liquid filtration and circulation step and the second residual liquid filtration and circulation step are alternately repeated.

  According to the embodiment of the present invention, there is a stock solution charging step for supplying all the stock solution from the stock solution tank into the leaf filter before the first residual solution filtration and circulation step or the second residual solution filtration and circulation step.

  Further, after the first residual liquid filtration / circulation step or the second residual liquid filtration / circulation step, the raw liquid is supplied from the lower part of the leaf filter to the residual liquid filtration mechanism of the leaf filter, and the residual liquid is filtered. A filtrate collecting step of collecting the filtrate without passing turbidity in the filtrate tank is provided.

  According to the apparatus and method of the present invention described above, with the filtrate recovery valve closed and the filtrate circulation pipe communicated, the stock solution filtration line and the residue filtrate filtration line are alternately switched, Since the second residual liquid filtration and circulation process is repeated alternately, the residual liquid is circulated through the leaf filter from the lower part of the stock solution tank or the leaf filter until the turbid residual liquid that has passed through the leaf filter changes to a non-turbid filtrate. Since the cake layer is formed on the surface of the filter element in the leaf filter, even when the amount of the stock solution is small and the volume in the leaf filter is less than that, the turbidity of the filtrate can be prevented and satisfactory filtration can be performed.

In addition, since the suction port of the pump is switched by alternately switching the stock solution filtration line and the residual solution filtration line, the same pump can be used for both the stock solution and the residual solution, minimizing additional equipment. it can.

It is a schematic diagram of the conventional leaf filter. It is a block diagram of the filtration apparatus of the stock solution by this invention. It is explanatory drawing of the filtration method of the stock solution by this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

FIG. 2 is a block diagram of a stock solution filtering apparatus according to the present invention.
In this figure, the stock solution filtering apparatus according to the present invention includes a stock solution tank 12, a leaf filter 14, a stock solution pump 16, a filtrate tank 18, a stock solution filtration line L1, a residual solution filtration line L2, a filtrate collection pipe 25, and a filtrate circulation pipe 26. Is provided.

The stock solution tank 12 holds the stock solution 3. Further, the stock solution tank 12 is provided with a level meter 12a for detecting the level of the stock solution 3 so as to detect an empty or lowest level (LL) and a predetermined level (L).
The present invention is intended for the case where the volume of the stock solution 3 (stock solution amount) is small and less than the volume in the leaf filter 14. However, the present invention is not limited to this, and can also be applied to the case where the amount of the stock solution is larger than the volume in the leaf filter 14.

The leaf filter 14 has a residual liquid filtration mechanism 14a. The leaf filter 14 is the same as the leaf filter of FIG. 1 described above, and includes a filter element 1, a filter shaft 6, a filter nest 7, a rotation drive device 8, a vessel 9, and a discharge port 9a. Further, as shown in FIG. 1, at the time of residual liquid treatment, the residual liquid is circulated by a pump to accumulate the stock solution on each filter element 1 while overflowing (overflowing) from the outer peripheral portion onto the lower filter element. Liquid filtration is possible.
The residual liquid filtration mechanism is not limited to this configuration, and may be another known mechanism.

The stock solution pump 16 is a liquid pump that pressurizes and feeds the stock solution.
The filtrate tank 18 is a tank that collects and stores the filtrate 5 filtered by the leaf filter 14.
The filtrate collection pipe 25 is a pipe that has a filtrate collection valve V5 and collects the filtrate from the leaf filter 14 to the filtrate tank 18.
The filtrate circulation pipe 26 is a pipe that has a filtrate circulation valve V6 and circulates the filtrate to the stock solution tank 12 from between the leaf filter 14 and the filtrate recovery valve V5.

The stock solution filtration line L1 supplies the stock solution from the stock solution tank 12 to the residual solution filtration mechanism 14a of the leaf filter 14 and filters the residual solution.
The residual liquid filtration line L2 supplies the raw liquid from the lower part of the leaf filter 14 to the residual liquid filtration mechanism 14a of the leaf filter 14, and performs residual liquid filtration.

In this example, the stock solution filtration line L <b> 1 includes a first stock solution supply pipe 21 and a second stock solution supply pipe 22.
The first undiluted solution supply pipe 21 has a first undiluted solution valve V <b> 1 and is a pipe that supplies undiluted solution from the undiluted solution tank 12 to the suction port of the undiluted solution pump 16.
The second undiluted solution supply pipe 22 has a second undiluted solution valve V <b> 2 and is a pipe that supplies undiluted solution from the discharge port of the undiluted solution pump 16 to the residual solution filtering mechanism 14 a of the leaf filter 14.

The residual liquid filtration line L <b> 2 includes the second stock solution supply pipe 22 and the third stock solution supply pipe 23.
The third undiluted solution supply pipe 23 has a third undiluted solution valve V <b> 3 and is a pipe that supplies undiluted solution between the first undiluted solution valve V <b> 1 and the undiluted solution pump 16 from the lower part of the leaf filter 14.

With the above-described configuration, the filtrate recovery valve V5 is fully closed, and the first concentrate liquid valve V1, the second concentrate liquid valve V2, and the filtrate circulation valve V6 are opened, so that the concentrate is supplied from the concentrate tank 12 to the residual filtration mechanism 14a of the leaf filter 14. And the remaining liquid is filtered, and the turbid residual liquid that has passed through the leaf filter 14 can be collected in the stock solution tank 12.
Further, the filtrate recovery valve V5 and the first raw liquid valve V1 are fully closed, and the third raw liquid valve V3, the second raw liquid valve V2, and the filtrate circulation valve V6 are opened, so that the remaining liquid of the leaf filter 14 is opened from the lower part of the leaf filter 14. The stock solution can be supplied to the filtration mechanism 14 a to filter the residual solution, and the turbid residual solution that has passed through the leaf filter 14 can be collected in the stock solution tank 12.
The stock solution filtration line L1 and the residual solution filtration line L2 can be switched alternately.
Here, “passing” means that the liquid filtered by the leaf filter 14 is a turbid residual liquid 11, which is the same as “filtration” in terms of process.

In FIG. 2, the filtration device of the present invention further includes a fourth stock solution supply pipe 24, a pressurized gas pipe 27, and a gas vent pipe 28.
The fourth undiluted solution supply pipe 24 has a fourth undiluted solution valve V4 and is a pipe that supplies undiluted solution from between the undiluted solution pump 16 and the second undiluted solution valve V2 to the lower part of the leaf filter 14.
The pressurized gas pipe 27 is a pipe that has a pressurized gas valve V 7 and supplies pressurized gas to the upper part of the leaf filter 14.
The gas vent pipe 28 has a gas vent valve V8 and is a pipe that communicates between the second raw liquid valve V2 and the leaf filter 14 and the raw liquid tank 12.

With the configuration described above, the stock solution can be supplied from the stock solution tank 12 into the leaf filter 14 by opening the fourth stock solution valve V4.
Moreover, the liquid in the leaf filter 14 can be pressurized by opening the pressurized gas valve V7.
Moreover, the gas venting in the leaf filter 14 can be vented by opening the gas vent valve V8.
Each of the above-described valves is preferably a remotely operable on-off valve, but may be a flow rate adjusting valve as long as it can be fully closed.

FIG. 3 is an explanatory diagram of a method for filtering a stock solution according to the present invention. In this figure, (A) is the first step (raw solution charging step), (B) is the second step (second residual liquid filtration and circulation step), and (C) is the third step (first residual liquid filtration and circulation step). ) And (D) show the fourth step (filtrate recovery step).
In each figure, the white valve indicates the open state, the black valve indicates the fully closed state, the solid line piping indicates the communication state, and the broken line piping indicates the closed state.
Table 1 shows the state of the operating equipment in each stroke. The operating device P in this table is a stock solution pump 16.

  As shown in Table 1, the stock solution pump 16 (P in the table) is always in operation during the first to fourth steps.

3A, the valves V2, V3, V5, V6, V7 are fully closed, the valves V1, V4, V8 are opened, and the leaf filter 14 is opened from the stock solution tank 12. Supply all undiluted solution to. The gas in the leaf filter 14 is degassed into the stock solution tank 12 via the valve V8.
In this step, when the amount of the stock solution is small, the leaf filter 14 is not filled up and is stored below the leaf filter 14.

In the second step (second residual liquid filtration and circulation step) in FIG. 3B, the valves V5, V4, and V8 are fully closed, the valves V2, V3, V6, and V7 are opened while the valve V5 is fully closed. The turbidity that has passed through the leaf filter 14 via the filtrate circulation pipe 26 after supplying the raw solution from the lower part of the leaf filter 14 to the residue filtration mechanism 14a of the leaf filter 14 through the residue filter line L2 and filtering the residue. The remaining liquid is collected in the stock solution tank 12.
In this step, when the liquid level of the stock solution tank 12 rises and reaches a predetermined level L, the process is switched to the next third step.
In this step, the filtrate that has passed through the leaf filter 14 is cloudy until a cake layer is formed on the surface of the filter element.

In the third step (first residual liquid filtration and circulation step) in FIG. 3C, the valves V4, V5, and V8 are fully closed, the valve V3 is fully closed, and the valves V1, V2, V6, and V7 are opened. The stock solution is supplied from the stock solution tank 12 to the remaining solution filtration mechanism 14a of the leaf filter 14 through the stock solution filtration line L1, and the remaining solution is filtered, and the turbid residue that has passed through the leaf filter 14 through the filtrate circulation pipe 26. The liquid is collected in the stock solution tank 12.
In this step, the filtrate returned to the stock solution tank 12 is supplied to the leaf filter 14 again. This step is switched to the second step when the liquid level of the stock solution tank 12 descends and reaches a predetermined minimum level LL. At this time, the residual liquid filtration is continued, and the filtrate returns to the stock solution tank 12.
In this step, the filtrate that has passed through the leaf filter 14 is cloudy until a cake layer is formed on the surface of the filter element.

While the second step (FIG. 3B) and the third step (FIG. 3C) are alternately repeated, a cake layer is formed on the surface of the filter element, and the filtrate becomes clear. After the filtrate becomes clear, the process is switched to the fourth step (filtrate recovery step).
This switching may be performed from either the second step (FIG. 3B) or the third step (FIG. 3C).

  In the fourth step (filtrate recovery step) in FIG. 3D, the valves V4 and V8 are fully closed, the valves V1 and V6 are fully closed, and the valves V2, V3, V5, and V7 are opened, and the remaining liquid is filtered. The undisturbed filtrate that has passed through the leaf filter 14 through the filtrate collection pipe 25 is supplied through the line L2 from the lower part of the leaf filter 14 to the residual liquid filtration mechanism 14a of the leaf filter 14 for residual liquid filtration. It collects in the filtrate tank 18.

  In this example, the fourth step is performed after the third step (FIG. 3C), and the fourth step is performed after the second step (FIG. 3B). Filter the residue through filtration line L1. Others are the same.

In FIG. 3, the first step (stock solution charging step) (FIG. 3A) is omitted, and the first residual liquid filtration and circulation step (FIG. 3C) and the second residual liquid filtration and circulation step (FIG. You may implement in order of B)).
Further, if there is no rising portion in the filtrate circulation pipe 26, the liquid flows through the pipe line 26 by the head, so the pressure applied at the valve V7 becomes the filtration pressure. When the filtrate circulation pipe 26 has a rising portion, a part of the pressure of the pressurized gas supplied through the valve V7 is used for canceling the pressure of the rising portion.

Whether or not the filtrate that has passed through the leaf filter 14 has become clear is basically determined by whether or not solid matter is leaking into the filtrate.
For example, (1) A sight glass is attached to the filtrate pipe for visual judgment, (2) A numeric value is judged by attaching a turbidimeter to the filtrate pipe, and (3) A sampling port is attached to the filtrate pipe. It is preferable that the determination is made by sampling the filtrate with the
When the properties of the stock solution are stable, the time required for the filtrate to reach the acceptance standard may be grasped in advance, and the above steps may be switched using a timer or the like.

  In addition, when considering contamination of solids when switching the type of processed product, the solids remaining on the tank wall or the back side of the filter leaf can be removed by circulating the clear filtrate in the system even after the clear filtrate is obtained. Since it can be washed away, it is preferable to delay the transition to the filtrate recovery step (FIG. 3D).

  According to the apparatus and method of the present invention described above, the first residual liquid is switched by alternately switching the raw liquid filtration line L1 and the residual liquid filtration line L2 with the filtrate recovery valve V5 closed and the filtrate circulation pipe 26 communicated. Since the filtration circulation process and the second residual liquid filtration circulation process are alternately repeated, the leaf filter is changed from the lower part of the stock solution tank 12 or the leaf filter 14 until the turbid residual liquid that has passed through the leaf filter 14 changes to a turbid filtrate. 14 circulates the remaining liquid to form a cake layer on the surface of the filter element in the leaf filter, so that even if the amount of the stock solution is small and less than the volume in the leaf filter, the turbidity of the filtrate is prevented and satisfied. Filtration.

  Moreover, since the suction port of the pump is switched by alternately switching the raw liquid filtration line L1 and the residual liquid filtration line L2, the same pump can be used for both the raw liquid and the residual liquid, minimizing additional equipment. be able to.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention.

1 filter element, 2 cake layers, 3 stock solutions,
4 solids (cake), 5 filtrate, 6 filter shaft,
7 Filter nest, 8 Rotation drive, 9 Vessel,
9a outlet, 11 residual liquid,
12 Stock solution tank, 13 Stock solution supply pipe, 13a Stock solution valve,
14 leaf filter, 16 stock solution pump,
18 filtrate tank,
21 first stock solution supply pipe, 22 second stock solution supply pipe,
23 3rd stock solution supply pipe, 24 4th stock solution supply pipe,
25 filtrate recovery pipe, 26 filtrate circulation pipe,
27 Pressurized gas pipe, 28 Degassing pipe,
L1 stock solution filtration line, L2 residual solution filtration line,
V1 first concentrate valve, V2 second concentrate valve,
V3 3rd concentrate valve, V4 4th concentrate valve,
V5 filtrate recovery valve, V6 filtrate circulation valve,
V7 pressurized gas valve, V8 vent valve

Claims (6)

A stock solution tank that holds the stock solution, a leaf filter having a residual liquid filtration mechanism, a stock solution pump that pumps the stock solution, a filtrate tank that collects the filtrate filtered by the leaf filter,
A stock solution filtration line for supplying a stock solution from the stock solution tank to a leaf filter residual fluid filtration mechanism and filtering the residual solution;
A residual liquid filtration line for supplying a raw liquid from a lower part of the leaf filter to a residual liquid filtration mechanism of the leaf filter and filtering the residual liquid;
A filtrate recovery pipe having a filtrate recovery valve and recovering the filtrate from the leaf filter to the filtrate tank;
A filtrate circulation pipe that has a filtrate circulation valve and circulates the filtrate to the stock solution tank from between the leaf filter and the filtrate recovery valve;
An undiluted solution filtration apparatus, wherein the undiluted solution filtration line and the remaining liquor filtration line are alternately switched in a state where the filtrate collection valve is closed and the filtrate circulation pipe is communicated. The stock solution filtration line includes a first stock solution supply pipe that has a first stock solution valve and supplies a stock solution from the stock solution tank to a suction port of the stock solution pump, and a second stock solution valve that passes through the discharge port of the stock solution pump. A second stock solution supply pipe for supplying a stock solution to the residual liquid filtration mechanism of the leaf filter,
The residual liquid filtration line includes a second raw liquid supply pipe, a third raw liquid supply pipe having a third raw liquid valve, and supplying a raw liquid between the first raw liquid valve and the raw liquid pump from a lower portion of the leaf filter; The undiluted solution filtration apparatus according to claim 1, comprising :   A fourth undiluted solution valve having a fourth undiluted solution valve for supplying undiluted solution to the lower portion of the leaf filter from between the undiluted solution pump and the second undiluted solution valve; and a pressurized gas valve for pressurizing the upper portion of the leaf filter 2. A pressurized gas pipe for supplying a gas; and a gas vent pipe having a gas vent valve and communicating between the second raw liquid valve and a leaf filter and the raw liquid tank. Stock solution filtration equipment. A first residual liquid filtration and circulation step of supplying the raw liquid from the raw liquid tank to the residual liquid filtration mechanism of the leaf filter and performing residual liquid filtration, and collecting the turbid residual liquid that has passed through the leaf filter to the raw liquid tank;
A second residual liquid filtration / circulation step of supplying a raw liquid from the lower part of the leaf filter to the residual liquid filtration mechanism of the leaf filter, filtering the residual liquid, and collecting the turbid residual liquid that has passed through the leaf filter in the raw liquid tank And
A method for filtering a stock solution, wherein the first residual liquid filtration and circulation step and the second residual liquid filtration and circulation step are alternately repeated.   5. The method according to claim 4, further comprising a stock solution filling step of supplying all of the stock solution from the stock solution tank into the leaf filter before the first residue solution filtration and circulation step or the second residue solution filtration and circulation step. Filtration method of stock solution.   After the first residual liquid filtration / circulation step or the second residual liquid filtration / circulation step, the raw liquid was supplied from the lower part of the leaf filter to the residual liquid filtration mechanism of the leaf filter to perform the residual liquid filtration, and passed through the leaf filter. The method for filtering a stock solution according to claim 4, further comprising a filtrate recovery step of recovering a filtrate having no turbidity in the filtrate tank.

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