JP2000051669A - Hollow fiber membrane module fitted with lower cap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance filtering treatment by a hollow fiber membrane module and low pressure air backwashing properties. SOLUTION: In order to enhance filtering treatment by a hollow fiber membrane module and low pressure air backwashing properties removing the suspended matter collected and accumulated on the outer surfaces of hollow fiber membrane by low pressure air backwashing, a cap 55 is provided to the lower end member 31' of the outer cylinder 51 for inserting the hollow fiber membrane module and a plurality of water collecting holes 56 for supplying water and introducing water or air at a time of backwashing are provided to the end surface of the cap 55.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow fiber membrane filtration device having a plurality of hollow fiber membrane modules in a container for filtering a stock solution, and more particularly to a lower end of an outer cylinder for inserting a hollow fiber membrane module. The present invention relates to a hollow fiber membrane module provided with a cap, and provided with a plurality of water collecting holes on an end face of the cap for introducing water or air for water supply and backwashing.

[0002]

2. Description of the Related Art Conventionally, in a nuclear power plant, a filtration device used for separating and removing suspended matter mainly composed of iron rust and the like present in condensate and radioactive waste liquid has conventionally been used for filtering powder ion-exchange resin and the like. A pre-coat type filtration device that pre-coats the auxiliary material on a fibrous or stainless steel wire mesh element and separates and removes suspended matter with a filter aid pre-coat layer has been adopted. Hollow fiber membrane filtration devices have been adopted.
Since the hollow fiber membrane type filtration device does not use a filter aid, the filter aid contained in the waste liquid generated by the precoat type filter device is unnecessary, and the amount of waste generated is reduced. In addition, since filtration is performed through the pores of the hollow fiber membrane, the pore size can be selected depending on the properties of the stock solution, and the removal performance is excellent, so it is widely used in water treatment equipment for removing various suspended solids. I have.

FIG. 5 shows a schematic configuration around a filter of a hollow fiber membrane type filtration device. Hollow fiber membrane module 5
Are suspended from a partition plate 3 sandwiched between a trunk container 1 and a lid container 2, and are fixed by a holding plate 4.

[0004] The undiluted solution required for the filtration process is a undiluted solution inlet valve 1
1. The solution is introduced into the body container 1 via the undiluted solution inlet tube 12, filtered by the hollow fiber membrane bundled in the hollow fiber membrane module of the hollow fiber membrane module 5, collected in the lid container 2, and treated liquid outlet tube. 13, is sent to the downstream system through the processing liquid outlet valve 14. The suspension separated by this filtration is captured and accumulated on the outer surface of the hollow fiber membrane, whereby the pores opened in the hollow fiber membrane are gradually closed, whereby the filtration resistance of the hollow fiber membrane increases, The filtration differential pressure increases. When the filtration pressure difference reaches a specified value, the hollow fiber membrane is backwashed.

[0005] The back-flush of the hollow fiber membrane is performed by the lower air inlet valve 15,
A low-pressure air backwash for vibrating the hollow fiber membrane to remove suspended matter by low-pressure air supplied from the lower air inlet pipe 16;
There is a high-pressure air backwash in which the processing liquid held in the lid container 2 is pumped by high-pressure air supplied from the upper air inlet valve 19 and the upper air inlet pipe 20 and backwashed from the inside to the outside of the hollow fiber membrane. Alternatively, a suspension captured by the hollow fiber membrane is removed by a combination of both. The air used for the backwash is exhausted through a vent pipe 17 and a vent valve 18, and
Further, the liquid retained in the body container 1 containing the suspended matter is discharged through the drain pipe 21 and the drain valve 22.

FIG. 3 shows an example of a conventional structure of a hollow fiber membrane module 5 for filtering a stock solution. In the hollow fiber membrane module 5, a large number of hollow fiber membranes 40 having linearly formed micropores are arranged and bonded and fixed to an end member 31. The end member 31 at the uppermost end of the hollow fiber membrane module 5 forms a wide end so as to be connected to the partition plate 3, and a sealing material 32 is provided between the end member 31 and the partition plate 3 to provide a stock solution. And the processing liquid are not mixed, and are fixed by the holding plate 4.

The undiluted solution containing the suspension is supplied to a skirt 57 provided at the lower end of the outer cylinder 51 for inserting the hollow fiber membrane module.
Is guided to the guide tube 54 of the lower end member 31 ′ from the opening formed by the above, is supplied to the hollow fiber membrane 40, and is filtered by flowing from the outside to the inside of the hollow fiber membrane 40.

The skirt 57 provided on the hollow fiber membrane module insertion outer cylinder 51 is in an open state in order to supply a stock solution to the hollow fiber membrane module 5. Here, the water pressure of the stock solution when supplied into the skirt 57 is directly affected on the end face of the lower end member 31 'to which the thread of the hollow fiber membrane 40 is adhered and fixed without being affected by the resistance action. .

As a result, as the flow rate of the stock solution supplied to the opening formed by the skirt 57 increases,
The water flow rate is increased, and the water pressure of the stock solution when supplied is also increased.

That is, when the water pressure value applied to the end face of the lower end member 31 'exceeds the allowable value range of the adhesive used for bonding and fixing the yarn of the hollow fiber membrane 40, the hollow fiber membrane Forty threads have the potential to release from the adhesive.

Accordingly, as the flow rate of the stock solution supplied during the filtration process increases, the water pressure acting on the end face of the lower end member 31 'also increases, so that the thread of the hollow fiber membrane 40 separates from the adhesive. In order to prevent this, it is necessary to increase the amount of adhesive to strengthen the lower end member 31 '.

Next, the backwashing of the hollow fiber membrane module 5 will be described. The low-pressure air in the low-pressure air backwash is supplied from the opening formed by the skirt 57 provided at the lower end of the hollow fiber membrane module insertion outer tube 51 to the guide pipe 54 of the lower end member 31 'in the same manner as in the filtration process. Is supplied to the hollow fiber membrane module 5 and vibrates the hollow fiber membrane to perform a backwash for removing suspended matter.

Here, the outer cylinder 5 for inserting the hollow fiber membrane module
The skirt 57 provided at 1 is open to supply low-pressure air to the hollow fiber membrane module 5. Here, in the low-pressure air supplied into the skirt 57, particularly in the low-pressure air supplied near the skirt 57,
Since the supplied portion is in an open state and flows out of the skirt 57, the amount of low-pressure air supplied to the end face of the lower end member 31 'may vary due to a difference in the end face portion. have.

As a result, the amount of low-pressure air supplied into the skirt 57 varies depending on the position of the end surface of the lower end member 31 '. There is a possibility that the air amount sometimes required cannot be supplied to the hollow fiber membrane module 5.

That is, the air does not sufficiently come into contact with the hollow fiber membrane during the low pressure air backwash because the amount of air supplied to the hollow fiber membrane 40 is small. In other words, air is not evenly dispersed throughout the hollow fiber membrane module because the membrane does not sway, and does not propagate throughout the hollow fiber membrane, so air is trapped in the micropores of the hollow fiber membrane at locations where there is little air contact with the membrane. It is not possible to completely remove the suspended suspension, and there is a possibility that a part remains.

Therefore, immediately after the low-pressure air backwashing, the filter pressure difference does not recover to the initial filtration pressure difference at which the hollow fiber membrane was subjected to the filtration, becomes higher than the initial filtration pressure difference, and then the filtration is performed again. The filtration pressure difference when subjected to the treatment also increases by that amount. By repeating this filtration treatment and backwashing, the suspension remaining on the outer surface of the hollow fiber membrane without being removed by backwashing gradually increases, so that the time required for increasing the filtration pressure difference also becomes shorter. , The recovery of the filtration pressure difference due to backwashing is substantially eliminated, the pressure difference becomes an allowable pressure difference, and the further use of the hollow fiber membrane becomes impossible.

FIG. 4 shows an example of a change in the pressure difference in water flow of the filtration device. This figure shows the relationship between the operation time and the filtration pressure difference when the water flow and low-pressure air backwashing of the hollow fiber membrane filtration device are repeated. The horizontal axis represents the operation time, and the vertical axis represents the pressure difference between the fluids contained in the inlet pipe 12 and the outlet pipe 13, that is, the filtration pressure difference. Curve a indicates a change in filtration differential pressure, and the filtration differential pressure gradually increases as the operation time elapses. This is because the suspension is accumulated on the surface of the hollow fiber membrane 40 and the hollow fiber membrane 40
This is because the filtration resistance increases. The filtration process was stopped at point B, backwashing was performed, and the reduced differential pressure was point C.

In the subsequent filtration process operation, the filtration process is stopped when the temperature reaches the vicinity of the point B differential pressure with the elapse of the operation time,
Perform backwash. Here, as described above, since a suspension remains on the outer surface of the hollow fiber membrane at each backwash, the differential pressure increase with the elapse of the filtration operation time is filtered to the differential pressure at point B, and filtration and backwashing are performed. When repeated, the operation interval A was shortened to B, C, and D due to the suspension remaining on the outer surface of the hollow fiber membrane, and the life of the hollow fiber membrane was also short.

A device related to this type of device is disclosed in, for example, Japanese Patent Application No. 10-12253 (reference).

[0020]

In the above prior art, since the water or air during the filtration treatment and the low-pressure air backwash is not uniformly supplied to the hollow fiber membrane 40, the filtration function by the hollow fiber membrane 40 is effective. And the suspended matter trapped on the outer surface of the hollow fiber membrane 40 after low-pressure air backwashing may remain.

This is because water at the time of the filtration process is supplied to the skirt 57 provided at the lower end of the outer tube 51 for inserting the hollow fiber membrane module.
The pressure of the water supplied from the opening formed by the skirt 57 is added directly to the end face of the lower end member 31 ', so that the flow rate of the water supplied from the opening of the skirt 57 increases. The water pressure value applied to the end face of the lower end member 31 'also increases. That is, if the water pressure value exceeds the allowable value range of the adhesive used when the yarn of the hollow fiber membrane 40 is bonded and fixed to the lower end member 31 ', the hollow fiber membrane 40
Has a possibility of peeling off from the adhesive, and in order to prevent this, the amount of adhesive used for the lower end member 31 'is increased.

In backwashing with low-pressure air, in the low-pressure air supplied from the opening formed by the skirt 57, and particularly in the low-pressure air supplied near the skirt 57, the supplied portion has an opening. State
Since the amount of low-pressure air supplied to the end face of the lower end member 31 ′ fluctuates due to the difference in the end face portion because it flows out of the skirt 57, the amount of air required for low-pressure air backwashing is reduced. This is because supply to the hollow fiber membrane module 5 becomes impossible.

An object of the present invention is to provide a hollow fiber membrane module with a lower cap, which can improve the filtration process using a hollow fiber membrane and the low-pressure air backwashing.

[0024]

The hollow fiber membrane module of the present invention has a cap on the lower end member of the outer cylinder for inserting the hollow fiber membrane module, and the end face of the cap is provided with water or air for water supply and backwashing. A plurality of water collecting holes for introducing water were provided.

As described above, it is intended to improve the filtering process using the hollow fiber membrane and the low pressure air backwashing.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, there is no difference in the function of filtering a stock solution through a hollow fiber membrane to remove suspended matter, and the function of the filter around a hollow fiber membrane type filtration device is different from that of the above-mentioned conventional example. Does not change.

That is, in this embodiment, the hollow fiber membrane module 5 is, as shown in FIG.
One or more pieces are suspended from a partition plate 3 sandwiched between a trunk container 1 and a lid container 2 in the same manner as the conventional hollow fiber membrane module 5, and fixed by a holding plate 4. The undiluted solution is guided into the body container 1 through the undiluted solution inlet valve 11 and the undiluted solution inlet pipe 12, and is filtered by the hollow fiber membrane in the hollow fiber membrane module 5. The processing liquid is collected in the lid container 2 and the processing liquid outlet pipe 1
3. The liquid is sent to the downstream system through the processing liquid outlet valve 14.

The back-flush of the hollow fiber membrane is performed by the lower air inlet valve 15,
A low-pressure air backwash with low-pressure air supplied from the lower air inlet pipe 16; an upper air inlet valve 19;
This is performed by high-pressure air backwashing with high-pressure air supplied thereto, and the air is discharged through a vent pipe 17 and a vent valve 18, and the liquid held in the container is drained by a drain pipe 21 and a drain valve 2.
Exhausted through 2.

FIG. 1 shows the structure of the hollow fiber membrane module in this embodiment.

The present embodiment is different from the conventional one in that a cap 55 is provided at the lower end of the outer tube 51 for inserting a hollow fiber membrane module, and water or air for supplying water and for back washing is introduced into the end face of the cap 55. This is because a plurality of water collecting holes 56 are provided.

Here, a cap 55 is provided at the lower end of the outer tube 51 for inserting a hollow fiber membrane module in this embodiment, and a plurality of water collecting holes 56 are provided at the end face of the cap 55 as shown in FIG. ing. Further, the distance from the end face of the hollow fiber membrane module where the lower end membranes are bundled and bonded and fixed to the water collecting hole 56 is, for example, about 20 mm or more as in the embodiment of FIG. About 1 from catch hole 56
By separating it by 0 mm or more, it has a function to collect the undiluted solution at the time of filtration.

This technique uses the conventional hollow fiber membrane module 4
Since the skirt 57 is provided at the lower end of the outer cylinder 51 for inserting the hollow fiber membrane module in 1 and is in an open state, the function is the same as that of collecting the undiluted solution in the opening. Conventionally, by providing the cap 55, the water pressure of the stock solution when supplied is absorbed by the cap 55.

Thus, compared with the case where the skirt 57 is provided at the lower end of the hollow cylinder 51 for inserting the hollow fiber membrane module, it is supplied to the end face of the lower end member 31 'to which the thread of the hollow fiber membrane 40 is adhered and fixed. The water pressure at the time can be kept low.

That is, the lower end member 31 'is subjected to the filtration process.
By suppressing the water pressure of the stock solution supplied to the end face of the hollow fiber membrane 40, it is possible to use the adhesive used when the thread of the hollow fiber membrane 40 is adhered and fixed within the allowable value range. The factor of peeling off from the adhesive is eliminated.

Also, in the low pressure air backwash, similarly to the filtration process, a function for collecting the low pressure air supplied at the time of the low pressure air backwash into the water collecting portion formed by the cap 55 is provided. I have. According to this technology, a skirt 57 is provided at the lower end of the hollow fiber membrane module insertion outer cylinder 51 in the conventional hollow fiber membrane module 41 and the hollow fiber membrane module 41 is in an open state.
It has the same function as collecting air in the opening. Conventionally,
By providing the cap 55 and further providing the water collecting hole 56 on the end face of the cap 55, it is possible to prevent the low-pressure air supplied to the water collecting portion formed by the cap 55 from flowing out.

Thus, the conventional hollow fiber membrane module 4
As compared with the case where the skirt 57 is provided at the lower end of the hollow fiber membrane module insertion outer cylinder 51 in 1, the low-pressure air amount is evenly supplied to the end face of the lower end member 31 ′.

That is, the amount of low-pressure air supplied at the time of back-washing low-pressure air does not fluctuate at the end surface of the lower end member 31 '. The amount of air required for washing can be supplied to the hollow fiber membrane module 5.

As described above, the water or the air supplied during the filtration process and the low-pressure air backwash pass through the water collecting hole 56 and pass through the guide tube 54 provided in the lower end member 31 ′.
0 is supplied. That is, since a constant amount of water or air can always be secured during the filtration process and the low-pressure air backwash, the filtration process function and the low-pressure air backwash by the hollow fiber membrane 40 are efficiently performed.

[0040]

According to the present invention, at the time of filtration treatment with the hollow fiber membrane and at the time of low pressure air backwashing in which suspended matter trapped and accumulated on the outer surface of the hollow fiber membrane is removed by low pressure air backwash,
By having a cap on the lower end member of the hollow fiber membrane module insertion outer cylinder, by providing a plurality of water collection holes for water supply and for introducing water or air during backwashing on the end face of the cap, Since a constant amount of water or air can be always secured during the filtration process and the low-pressure air backwash, the effect of efficiently performing the filtration process function by the hollow fiber membrane and the low-pressure air backwash can be achieved.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing the structure of a hollow fiber membrane module according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a side sectional view showing the structure of a conventional hollow fiber membrane module.

FIG. 4 is a characteristic diagram showing the performance of a conventional hollow fiber membrane filtration device.

FIG. 5 is a detailed view showing a schematic configuration around a hollow fiber membrane filtration device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Body container, 2 ... Lid container, 3 ... Partition plate, 4 ... Holding plate, 5
... hollow fiber membrane module, 31 ... end member, 32 ... sealing material, 40 ... hollow fiber membrane, 41 ... conventional hollow fiber membrane module, 42 ... hollow fiber membrane module of the present invention, 47 ... backwash air hole, 51 ... An outer cylinder for inserting a hollow fiber membrane module, 54 ... a guide tube, 55 ... a cap, 56 ... a water collecting hole, 57 ... a skirt.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Yoshihiro Shiozawa 3-2-1, Sachimachi, Hitachi-shi, Ibaraki Hitachi Engineering Co., Ltd. (72) Kentaro Hirabayashi 3-1-1, Sachimachi, Hitachi-shi, Ibaraki No. 1 F-term in Hitachi, Ltd. Hitachi Plant (reference) 4D006 GA02 HA03 HA19 JA08A JA10A JA23Z JA29A JA31A KC02 KC03 KC14 MA01 PB03

Claims (3)

[Claims] 1. A container having a stock solution inlet and a processing solution outlet, a partition plate provided in the container, and a hollow fiber membrane filter provided with one or more hollow fiber membrane modules fixed to the partition plate. An outer cylinder for inserting a hollow fiber membrane module provided with a number of holes provided for introducing and discharging water or air during water supply and back washing, and an upper end fixed to the upper end of the outer cylinder and suspended from the partition plate The member and the hollow fiber membrane module provided with a cap at the lower end of the outer cylinder, wherein a plurality of water collecting holes for introducing water or air for water supply and backwashing are provided on an end surface of the lower end cap. Hollow fiber membrane module. 2. The cap at the lower end of the outer cylinder for inserting a hollow fiber membrane module has a function of supplying water to the hollow fiber membrane module and collecting water or air during backwashing. 2. The hollow fiber membrane module according to 1. 3. The water collecting hole provided in the end face of the cap has a function of dispersing water or air introduced into the lower end of the hollow fiber membrane module.
3. The hollow fiber membrane module according to item 1.