JPH06226012A - Filtering and concentrating method and device - Google Patents

Abstract

PURPOSE:To shorten switching time between a filtration process and a backwash process and to increase the operation efficiency of a filter by only opening/ closing a discharge valve with a crude liquid pump operated to continuously switching between the filtration process and the backwash process. CONSTITUTION:When a filtration process is continued, that is, when a crude liquid pump 5 is operated with a discharge valve 6 closed, a suction pump 7 is operated to evacuate a waste liquid tank 4. When the discharge valve 6 is rapidly opened, a crude liquid in a crude liquid tank 2b is sucked into a waste liquid tank 4 through a discharge liquid pass D and the crude liquid tank 2b is temporarily evacuated. Then a filtered liquid in a filtered liquid chamber 2c in the pressure accumulated state backflows to the crude liquid chamber 2b through a filter medium 2d and cake on the filter medium 2d is removed to fall into the crude liquid in the crude liquid chamber 2b. When a discharge valve 6 is closed after a prescribed time, for example, a time of about 10sec has elapsed, the baskwash process is finished to restore the filtration process. On the other hand, the cake settles and is accumulated in the bottom part of the crude liquid chamber 2b and is sucked and discharged as waste liquid into a waste liquid tank 4 in the next backwash process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for filtering a suspension to separate and collect a filtrate and a concentrated suspension,
In particular, the present invention relates to a filtration / concentration device and a filtration / concentration method in which filtration efficiency is improved by increasing the removal efficiency of the residue accumulated on the filter medium.

[0002]

2. Description of the Related Art As a device for filtering and concentrating a large amount of a suspension, a vertical type filter is provided in which a cylindrical filter medium is vertically provided in a lower stock solution chamber, and a filtrate chamber communicating with the inside of the cylindrical filter medium is provided in an upper part. Filters are known. In order to filter and concentrate the stock solution using such a filter, the stock solution is pressurized and supplied to the stock solution chamber by a pump or the like to recover the filtrate from the filtrate chamber. When filter residue accumulates around the filter medium and the filtration efficiency decreases, first stop the supply of the stock solution, then open the drainage pipe connected to the bottom of the stock solution chamber to discharge the stock solution and, at the same time, remove the filtrate if necessary. The filter medium is backwashed by supplying pressurized air to the chamber and backflowing the filtrate in the filtrate chamber, and the liquid containing the filter cake separated from the filter medium is sent to a separately provided waste liquid tank through a drain pipe. In order to recover the filtration efficiency.

However, in such a filtration and concentration method, when the filter residue is accumulated on the filter material, the filtration operation is stopped and the filter material is washed and regenerated. Therefore, when treating a stock solution having a high suspension concentration, Since the filtration process must be frequently interrupted, and not only the time required for the backwash process but also the time required for switching the processes are long, there is a problem that the operating efficiency of the filter is reduced. .

On the other hand, in order to shorten the time required for the backwashing step of the filter medium, a means for increasing the pressure of air supplied into the filtrate chamber to accelerate the backflow rate of the filtrate has been conventionally adopted. When the pressure is increased, a device with high pressure resistance is required, which is economically limited, and there is a limit to time reduction, and there is a problem that the filter medium is easily damaged.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention is intended to provide a filtration concentrating device and a filtration concentrating method capable of further increasing the operation efficiency of the filtration device. The object of the present invention is to achieve the above object by shortening the switching time between the backwashing step and the backwashing step and simplifying the backwashing step.

[0006]

Therefore, the filtration and concentrating apparatus of the present invention comprises a stock solution storage tank, a filter provided with a stock solution chamber and a filtrate chamber with a filter material therebetween, a filtrate storage tank, a waste solution tank, and a stock solution pump. A stock solution supply path connecting the stock solution storage tank and the stock solution chamber via a filtrate recovery path connecting the stock solution chamber and the filtrate storage tank; and a drainage path connecting the bottom of the stock solution chamber and the waste solution tank, It is provided with a suction pump capable of removing the contents of the waste liquid tank under reduced pressure.

The filtration and concentration method of the present invention uses the above-described filtration and concentration device to discharge the stock solution from the stock solution storage tank through the stock solution supply passage to the filter under pressure to collect the filtrate into the filtrate storage tank. The liquid channel is suddenly opened and the concentrated residue of the residue is rapidly discharged from the bottom of the stock solution chamber into the waste tank which has been decompressed by a suction pump in advance, and the filtrate flowing back from the filtrate chamber is used to remove the residue from the filter medium. It is characterized by closing the passage and returning to the filtration operation.

[0008]

According to the present invention, the backwashing process can be started only by opening the valve of the drainage path while the stock solution pump is operating and the filtering process is being performed, and the backwashing process can be performed only by closing the valve. The process can return to the filtration process. Therefore, when the backwashing of the filter medium is easy because the accumulation of filter residue is small and the backwashing is carried out for a short period of time, the operation of recovering the filtration efficiency is repeated to carry out continuous operation for a long time, It is possible to greatly improve operating efficiency.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The filtration and concentrating device of the present invention will be described below with reference to FIG. In the figure, 1 is a stock solution storage tank, 2 is a filter, 3 is a filtrate storage tank, and 4 is a waste solution tank. The filter 2 has a stock solution chamber 2b in the lower part and a filtrate chamber 2c in the upper part with a partition plate 2a in the center part sandwiched therebetween. Further, a cylindrical filter medium 2d is vertically provided on the partition plate 2a, and the inside of the filter medium 2d communicates with the filtrate chamber 2c.

The stock solution pump 5 is provided in the middle of a stock solution supply path A which connects the stock solution storage tank 1 and the stock solution chamber 2b.
A stock solution return path B for returning the stock solution to the stock solution storage tank 1 is provided separately from the stock solution supply path A from the secondary side of the stock solution pump 5. On the other hand, the filtrate from the filtrate chamber 2c is sent to the filtrate storage tank 3 through the filtrate recovery path C, and the stock solution chamber 2b is also used.
The waste liquid can be dropped into the waste liquid tank 4 from the bottom through the drain valve D via the drain valve 6. The waste liquid and the gas in the waste liquid tank 4 are sucked by the suction pump 7 and sent to a waste liquid processing device (not shown). Therefore, the waste liquid tank 4 is kept depressurized by the operation of the suction pump 7.

When carrying out the step of filtering the stock solution using the filtration and concentrating device thus constructed, the stock solution pump 5 is operated to feed the stock solution in the stock solution storage tank 1 through the stock solution supply passage A into the stock solution chamber 2b. , A filtrate recovery passage C from the filtrate chamber 2c in which the filtrate filtered by the filter material 2d is in a pressure-accumulated state.
And then collected in the filtrate storage tank 3. At this time, the undiluted solution return passage B may be slightly opened so that part of the undiluted solution returns to the undiluted solution storage tank 1 in order to adjust the filtration rate.

When the filtration process is continued in this way, filter residue is deposited on the filter medium 2d and the filtration rate gradually decreases. Therefore, the stock solution return passage C is narrowed to reduce the amount of the stock solution returned, and the stock solution chamber 2b.
It is possible to increase the internal pressure of the resin while maintaining the filtration rate so as not to decrease. However, in the present invention, it is better to move to the next backwashing step before the amount of the accumulated filter cake becomes too large.

In the backwashing step in the present invention, the suction pump 7 is operated in advance while the stock solution pump 5 is being operated while the filtration step as described above is being continued, that is, with the discharge valve 6 being closed. This is performed when the pressure inside the tank 4 is reduced. That is, when the discharge valve 6 is suddenly opened during the continuation of the filtration process, the stock solution in the stock solution chamber 2b is sucked into the waste solution tank 4 through the drainage path D, and the stock solution chamber 2b is temporarily depressurized. Then, the pressure accumulation state and the filtrate in the filtrate chamber 2c flow back to the stock solution chamber 2b through the filter medium 2d, and the filter residue on the filter material 2d is peeled off and dropped into the stock solution in the stock solution chamber 2b.

When the discharge valve 6 is closed after a lapse of a predetermined time, for example, about 10 seconds, the backwashing process ends and the process returns to the filtering process. At that time, most of the filter cake separated from the filter medium 2d and floating in the undiluted solution is a lump, and again the filter medium 2d
Since it hardly deposits on the top and settles and deposits on the bottom of the stock solution chamber 2b, it does not hinder the execution of the next filtration step. The filter cake thus settled is sucked and discharged into the waste liquid tank 4 as a waste liquid mixed with the stock solution in the next backwashing step.

The filtration step and the backwash step can be continuously switched by simply opening and closing the discharge valve 6 while the stock solution pump 5 is operating. Since the backwashing time is very short and the backwashing time is very short, the filtration operation is hardly disturbed.

[0016]

According to the filtration and concentration method of the present invention, it is possible to carry out while continuously switching the filtration and the backwash while the stock solution pump is operating. Therefore, there is no need to wait when switching between the filtration step and the backwash step. The time is not required and the ratio of the actual filtering time to the operating time of the filter, that is, the operating efficiency of the filter can be significantly increased, and the operating efficiency is not so high even if frequent backwashing is performed for a short time. Since it does not decrease, the continuous operation time of the filter can be greatly extended, and thus a large filtering capacity is exhibited in comparison with the scale of the apparatus. Furthermore, the filtration concentrating device of the present invention is a device suitable for carrying out the filtration concentrating method of the present invention. Since the starting frequency of the stock solution pump can be greatly reduced, the power consumption at the time of starting is reduced, and the capacity of the pump operating power source There is an advantage that it does not need to be taken large and is economical and has a long life. In addition, because it is not necessary to introduce pressurized air during backwashing, an economical device that does not require pressure resistance design can be assembled, and since it is not necessary to apply excessive filtration pressure, the damage to the filter medium is small. is there.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a filtration and concentration device of the present invention.

[Explanation of symbols]

 1 stock solution storage tank 2 filter 2a partition plate 2b stock solution chamber 2c filtrate room 2d filter medium 3 filtrate storage tank 4 waste solution tank 5 stock solution pump 6 discharge valve 7 suction pump A stock solution supply path B stock solution return path C filtrate recovery path D waste solution path

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Yanashita 1-22-4 Noritakecho, Nakamura-ku, Nagoya, Aichi Tokan Mansion 906

Claims (2)

[Claims] 1. A stock solution storage tank, a filter provided with a stock solution chamber and a filtrate chamber with a filter medium in between, a filtrate storage tank, a waste solution tank, and a stock solution connecting the stock solution storage tank and the stock solution chamber via a stock solution pump. A supply path, a filtrate recovery path that connects the filtrate chamber and the filtrate storage tank, a drainage path that connects the bottom of the stock solution chamber and the waste liquid tank, and a suction pump that can remove the contents of the waste liquid tank under reduced pressure. A filtering and concentrating device. 2. Using the filtration concentrating device according to claim 1,
A waste liquid tank in which the drainage path is suddenly opened and the suction pump is used to reduce the pressure from the bottom of the stock solution chamber during the filtration operation in which the stock solution is pumped from the stock solution storage tank to the filtration machine and the filtrate is collected in the filtrate storage tank. A method for filtering and concentrating, characterized in that a concentrated filter solution is rapidly discharged into the filter material, and the filtered material flows backward from the filtrate chamber to remove the filter residue from the filter medium, and then the drainage channel is closed to return to the filtering operation.