JPS61111105A - Hollow yarn membrane filter - Google Patents

Abstract

PURPOSE:To reduce the amt. of a waste liq. discharged from a filter and to reduce the frequency of the exchange of the hollow yarn membrane filter by providing a gas storage part for regulating pressure, and regulating optionally the amt. of compressed gas for backwashing by the amt. of the gas stored in the gas storage part. CONSTITUTION:A separate tank 4 having a gas storage part 3 for regulating pressure is connected to the lower side part of the main body 2 of a hermetic vessel contg. a hollow yarn membrane filter 5. When a clad in a waste liq. is deposited on the surface of the filter 5 during the filtration of the waste liq., a valve 16 is opened to supply compressed gas from a gas supply pipe 11 into the main body 2 of the hermetic vessel until the pressure in the main body 2 becomes equal to the pressure of compressed gas, and then the valve 16 is closed. The volume of the gas stored in the gas storage part 3 is reduced as the pressure in the hermetic vessel 2 increases, the treating liq. equivalent to the reduced volume is refluxed to the surface from the inside of the filter 5, and the clad deposited on the surface of the filter 5 is removed. The amt. of the treating liq. to be refluxed can be controlled by regulating previously the amt. of gas to be stored in the gas storage part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a filtration device used, for example, in nuclear power generation equipment, and in particular to a hollow fiber membrane filtration device.

[Technical background of the invention and its problems] In boiling water nuclear power plants, it is difficult to remove insoluble solids (hereinafter referred to as crud) contained in condensate and radioactive liquid waste (hereinafter referred to as waste liquid). Therefore, a filtration device is used.

By the way, conventionally used filtration devices include, for example, filtration devices using a pre-coated filter such as powdered ion exchange resin, or filtration devices using filter paper, filter cloth, etc.; This method has not always been satisfactory in terms of the generation of secondary waste, filtration efficiency, and concentration rate of the substances to be filtered and separated.

In recent years, crud in waste liquid has been removed by a hollow fiber membrane filtration device using a hollow fiber membrane filter.

Such a hollow fiber membrane filtration device is configured such that waste liquid flows into the waste liquid supply pipe of the closed container, is filtered by passing through the hollow fiber membrane filter, and flows out from the treated liquid discharge pipe. At this time, the crud in the waste liquid adheres to the surface of the hollow fiber membrane filter, so as the waste liquid continues to be processed, the differential pressure before and after the filtration device (filtration differential pressure) increases, and the filtration function of the hollow fiber membrane filtration device increases. Therefore, it is necessary to perform backwashing to remove the crud adhering to the surface of the hollow fiber membrane filter.

Conventional backwashing involves introducing pressurized gas into the treated water outlet or the treated water side of a sealed container, causing the treated water to flow back with this pressurized gas, and further applying pressure to the hollow fiber membrane filter. This is done by passing pressurized gas. That is, the backflowing treated water 1 is configured so that the cladding is separated from the surface of the hollow fiber membrane filter 1 by pressurized gas, diffused into the waste liquid in the closed container, and then discharged from the concentrated sludge discharge pipe. After discharging this waste liquid, the treated water is flowed into the closed container and filtered again. However, in the conventional backwashing method described above, the waste liquid in the closed container must be discharged every time backwashing is completed, and the amount of waste liquid discharged is large. Moreover, there was a problem in that the concentration of crud in the waste liquid was low.

Therefore, as a method to reduce the amount of waste liquid discharged from the filtration device and increase the crud concentration in the waste liquid, after performing a certain amount of filtration treatment, pressurized gas is supplied from the pressurized gas supply pipe to the closed container. A possible filtration treatment method is to supply the treated liquid to the liquid side, make the treated liquid flow back with pressurized gas, and then repeat the filtration process a predetermined number of times, and then discharge the waste liquid from the concentrated sludge discharge pipe. .

However, when this filtration treatment method is applied to a conventional hollow fiber membrane filtration device, there are variations in the amount of processing liquid that flows back with pressurized gas and removes the crud on the surface of the hollow fiber membrane filter, and it is not sufficient to remove the crud. The problem is that a one-stop effect cannot be expected. To explain this in more detail, when introducing pressurized gas from a pressurized gas supply pipe into a closed container, all pipes other than the pressurized gas supply pipe connected to the sealed mother container are closed, and the Pressurized gas is supplied in an amount until the pressure inside the closed container becomes the same as the pressure of the pressurized gas.
The amount of pressurized gas supplied is the amount by which the gas present in the closed container is pressurized to the pressure of the pressurized gas and its volume is reduced. In the normal filtration treatment method, air is mixed into the waste liquid, and the amount of air that flows into the closed container of the filtration device is not large, and it is also unfavorable from the viewpoint of the performance of the pump and the like. Furthermore, depending on the material of the hollow fiber membrane, gases such as air may pass through it, resulting in it flowing out together with the processing liquid. Therefore, even if pressurized gas is supplied to a closed container,
The amount of processing liquid that flows back due to the pressurized gas is the same each time, and since the amount is small, there is a problem in that a sufficient crud removal effect due to backflow cannot be expected.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to reduce the amount of waste liquid discharged from a filtration device and to reduce the number of replacements of hollow fiber membrane filters, thereby improving efficiency. An object of the present invention is to provide a hollow fiber membrane filtration device that can be operated in a convenient manner.

[Summary of the Invention] In order to achieve the above object, the present invention provides a hollow fiber membrane filter for filtering waste liquid, a sealed container body housing the hollow fiber membrane filter, and a waste liquid flowing into the sealed container body. a supply pipe, a processing liquid discharge pipe through which the processing liquid filtered in the sealed container body flows out, a gas supply pipe which supplies pressurized gas to the hollow fiber membrane filter, and a waste liquid concentrated in the sealed container main body. A concentrated sludge discharge pipe to be discharged and a gas storage part for pressure adjustment provided on the waste liquid supply side are provided, and the amount of pressurized gas supplied from the gas supply pipe into the closed container is supplied to the gas storage part. This invention relates to a hollow fiber membrane filtration device that can be set to an arbitrary amount depending on the amount of gas to be stored.

[Embodiments of the invention] An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a hollow fiber membrane source/filter device that is an embodiment of the present invention. The hollow fiber membrane filtration device 1 has a divisible sealed container main body 2 having a hollow cylindrical shape. 4 is connected. Further, the hollow fiber membrane filter 5 is supported by a support plate 6 fixed to the upper part of the closed container main body 2.

Further, a waste liquid supply pipe 7 having a valve 12 is provided on the lower side surface of the closed container main body 2, and a processing liquid discharge pipe 8 having a valve 13 is provided in the upper part of the closed container main body 2. The processing liquid discharge pipe 8 is provided with a vent pipe 10 having a valve 15 and a pressurized gas supply pipe 11 having a valve 16. Furthermore, a concentrated sludge discharge pipe 9 having a valve 14 is installed at the bottom of the closed container body 2.

Next, the filtration method of the hollow fiber membrane filtration device 1 will be explained.

t Now valves 12.13 are open, valves 14.15.
16 is closed, the waste liquid flows into the closed container main body 2 from the waste liquid supply pipe 7 at a constant pressure, and passes through the hollow fiber membrane filter 5.
, and flows out from the processing liquid discharge pipe 8. At this time, the cladding components in the waste liquid adhere to the surface of the hollow fiber membrane filter 5. As crud accumulates on the surface of the hollow fiber membrane filter 5, the filtration differential pressure increases, and when it reaches a predetermined pressure, the water flow is stopped and each of the pipes installed in the waste liquid supply pipe 7 and the treated liquid discharge pipe 8 is Close valves 12 and 13.

Next, the valve provided in the gas supply pipe 11 is opened, and pressurized gas is supplied from the gas supply pipe 11 for a certain period of time until the pressure inside the closed container main body 2 becomes the same as the pressure of the supplied gas. Close consequent case 16 of supplying gas. Gas supply pipe 11
The pressurized gas supplied from the hollow fiber membrane filter 5 causes the processing liquid to flow backward from the inside to the surface of the hollow fiber membrane filter 5, thereby removing the crud attached to the surface of the hollow fiber membrane filter 5.

In this case, the field of the processing liquid to be flowed back is the gas storage part 3.
It is determined by the amount of gas (e.g. air) stored in the That is, the volume of the gas stored in the gas storage section 3 decreases as pressurized gas is supplied from the gas supply pipe 11 and the pressure inside the closed container 2 rises, and the processing liquid flows back by the reduced volume. I will do it. Therefore, by adjusting the amount of gas stored in advance, the amount of processing liquid flowing back can be adjusted. After the crud is removed by backflow of the processing liquid, the valve 15 installed in the vent pipe 10 is opened to release the pressure inside the closed container body 2, and the gas in the gas storage section 3 returns to its original volume.

Then, the valve 15 installed on the vent pipe 10 is closed, and the valves 12 and 13 installed on the waste liquid supply pipe 7 and the processing liquid discharge pipe 8 are opened again to allow water to flow. At this time, valves 14, 15, and 16 are closed.

The valve 14 installed in the tank is opened and the concentrated sludge is discharged.

It is also possible to carry out scrubbing by supplying pressurized gas before this discharge to further increase the crud removal efficiency.

According to this embodiment, since the waste liquid treatment is performed as described above, it is possible to adjust the amount of treated liquid flowing back depending on the amount of gas stored in the gas storage section 3. Therefore, the amount of processing liquid flowing back can be set in advance according to the processing capacity of the hollow fiber membrane filtration device 1, the filtration area of the hollow fiber membrane filter 5, and the properties of the waste liquid.

In the case of a conventional hollow fiber membrane filtration device that does not have a gas storage section,
The amount of treated liquid that flows back due to the pressurized gas is limited to the volume reduced due to pressurization of air bubbles introduced into the filtration device by mixing with the waste liquid, and the amount is inaccurate and small.

Therefore, according to this embodiment, when compared with the conventional filtration device, the crud concentration etc. can be reduced by about 20% due to the crud removal effect by closing the valves before and after the filtration device and supplying pressurized gas to the closed container body. (compared to about 10% in the conventional case).

Furthermore, the effect of removing the cladding slowed down the progress of clogging of the hollow fiber membrane filter, and the usable period of the hollow fiber membrane filter was approximately 1.5 times longer than that of conventional filtration devices.

As the concentration rate of the crud increases, the amount of concentrated sludge (backwash water amount) discharged from the filtration device decreases, reducing the load on the waste liquid treatment device installed downstream of the hollow fiber membrane filtration device of this embodiment. I can do it.

Further, in this embodiment, a vent pipe 10 is provided in order to release the pressure increased due to the supply of pressurized gas, but this vent pipe 10 can be omitted. This is because when water flow is restarted, the valve 12 of the processing liquid discharge pipe 7 is opened, which allows gas to escape and the pressure to drop.

FIG. 2 is a schematic cross-sectional view of a second embodiment of the invention.

Components that are the same as those in the first embodiment are given the same reference numerals, and detailed explanation thereof will be omitted.

The hollow fiber membrane filtration device 1A shown in FIG. 2 has a gas storage section 3A.
It has a structure in which a tank 4A provided with this is installed in a closed container main body 2A of a hollow fiber membrane filtration device 1A. Note that, as long as this gas storage section 3A is connected to the closed container main body 2A, the crud removal effect is the same as in the previous embodiment, regardless of where it is provided within the closed container main body 2A. Furthermore, when the gas storage section 3A is installed inside the airtight container 2A, the gas storage section 3A' itself does not function as a pressure vessel, so the wall surface may be made thin.
Therefore, the structure is simple. It also has the advantage of requiring less installation space.

FIG. 3 is a schematic cross-sectional view of a third embodiment of the invention.

Components that are the same as those in the first embodiment are designated by the same reference numerals.
A detailed explanation thereof will be omitted. The hollow fiber membrane filtration device 1B shown in FIG.
Since this 'separate tank 4B is installed in the waste liquid supply pipe 7, this gas storage section 3B is installed apart from the closed container main body 2B. Therefore, by attaching only the tank 4B to the existing hollow fiber membrane filtration device, the same crud concentration effect as in the first embodiment can be achieved.

Note that the gas storage section is not only installed in the waste liquid supply pipe as in this embodiment, but also installed in a pipe connected to the main body of the closed container, such as a concentrated sludge discharge pipe, or a drain branching from these pipes. It may be installed in piping, vent piping, etc.

[Effects of the Invention] As explained above, according to the hollow fiber membrane filtration device of the present invention, gas is stored inside the sealed container body housing the hollow fiber membrane filter or in a separate tank communicating with the sealed container body. In a waste liquid treatment method in which crud is removed by supplying pressurized gas to the closed container main body to the treatment liquid side of a hollow membrane filter and causing the treatment liquid to flow back by providing a storage part, the amount of treatment liquid that flows back. can be set arbitrarily. Therefore, the effect of removing crud caused by backflow of the processing liquid is improved, the amount of waste liquid discharged from the hollow fiber membrane filtration device is reduced, and the hollow fiber membrane filter is less likely to be clogged. This has the excellent effect of reducing the need for replacement.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of one embodiment of the present invention, FIG. 2 is a schematic cross-sectional view of a second embodiment of the present invention, and FIG.
FIG. 3 is a schematic cross-sectional view of an example of FIG. 1.1A, 1B...Hollow fiber membrane processing device 2.2A, 2B
... Airtight container body 3.3A, 3B ... Gas storage part 4.4A for pressure adjustment
, 4B...tank 5...hollow fiber membrane filter 6...support plate, 7...waste liquid supply pipe 8...
・Treatment liquid discharge pipe 9... Concentrated sludge discharge pipe 10... Vent pipe, 11... Gas supply pipe (7317
)Representative: Patent Attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2

Claims (3)

[Claims] (1) A hollow fiber membrane filter that filters waste liquid, a sealed container body housing the hollow fiber membrane filter, a waste liquid supply pipe that flows the waste liquid into the sealed container body, and a treated liquid filtered in the sealed container body. a gas supply pipe for supplying pressurized gas to the hollow fiber membrane filter; a concentrated sludge discharge pipe for discharging the waste liquid concentrated in the sealed container body; and a gas supply pipe provided on the waste liquid supply side. and a gas storage part for pressure adjustment, and the amount of pressurized gas supplied from the gas supply pipe into the closed container can be set to an arbitrary amount depending on the amount of gas stored in the gas storage part. A hollow fiber membrane filtration device characterized by: (2) The hollow fiber membrane filtration device according to claim 1, wherein the gas storage portion is formed within the closed container main body. (3) The hollow fiber membrane filtration device according to claim 1, wherein the gas storage section is formed of a tank separate from the main body of the closed container.