JPH01107806A - Hollow yarn membrane filter - Google Patents

Abstract

PURPOSE:To eliminate a weir and to reduce the pressure drop of a backwashing soln. bent pipe by transiently raising a backwashing soln. discharge pipeline provided to the lower part of a closed vessel to the same height as the lower surface of a tube plate on the outside of the closed vessel. CONSTITUTION:The inside of the tank-shaped closed vessel 31 is vertically separated by the horizontal tube plate 32, and a U-shaped hollow yarn membrane module 34 is hung from the opening 33 bored through the tube plate 32 through a housing 34a. The lower part separated by the tube plate 32 is used as the filtration chamber, and a pipeline 36 for supplying a liq. to be treated and the backwashing soln. bent pipeline 52 are provided at the lower part and allowed to communicate with each other. The backwashing soln. bent pipeline 52 is raised, and extended to the same height as the lower surface of the tube plate 32 or higher (a>=0). The backwashing soln. bent pipeline 52 is further bent downward, and water is injected into a waste liq. tank 57. Since the backwashing soln. does not overflow a weir, the pipeline pressure drop is eliminated, and the linear flow velocity ot the backwashing soln. can be increased even at a specified backwashing pressure.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a hollow fiber membrane filtration device installed in, for example, a condensate water supply system or a waste water system of a nuclear power plant, and particularly relates to a treatment device. The present invention relates to a hollow fiber membrane filtration device that can effectively backwash a hollow fiber membrane filter module with a liquid.

(Prior Art) As is well known, a hollow fiber membrane filtration device is a filtration device that uses a hollow fiber membrane made of a polymeric material in the form of long fibers as a filter element. Hollow fiber membrane filters have features such as being able to efficiently trap fine particulate insoluble contaminants and being reusable by backwashing, and are used in various liquid processing equipment. In the case of a hollow fiber membrane filtration device used in large-scale equipment such as a nuclear power plant, a hollow fiber membrane filter module in which a large number of hollow fiber membrane filters are bundled is used as a filter element.

FIG. 3 shows a conventional example of a hollow fiber membrane filtration device used in nuclear power plants and the like. The inside of a tank-shaped sealed container 1 is partitioned into upper and lower parts by a horizontal tube plate 2, and hollow fiber membrane filter modules 4 are suspended from a plurality of openings 3 in the tube plate 2, respectively. The lower space inside the closed container 1 in which the hollow fiber membrane filter module 4 is arranged is a filtration chamber 5.
A liquid to be treated supply pipe 6 is provided in communication with the lower part of the filtration chamber 5. Further, the upper space above the tube plate 2 of the closed container 1 is a processing liquid chamber 7, and a processing liquid discharge pipe 8 is provided in communication with the processing liquid chamber 7. The hollow fiber membrane module 4 shown in the figure is a so-called construction type module, and as shown in FIG. In the hollow fiber membrane module 60, a chamber (filtration chamber) 62 for collecting permeated water of the hollow fiber membrane is provided on the lower end surface, and in order to communicate the chamber 62 with the upper end surface, the inner axial direction of the hollow fiber membrane module 60 is provided. A conduit 63 is provided at the upper end of the hollow fiber membrane module 60, and a housing 64 for suspending the hollow fiber membrane module 60 on the tube plate 2 bundles the hollow fibers 61 at the upper end. It is composed of a plurality of couplings 65 that can be connected to each other.

By fitting and fixing the hollow fiber membrane modules 4 into the openings 3 of the tube plate 2, the processing liquid chambers 7 are respectively opened.

As a result, the liquid to be treated 10 supplied from the liquid to be treated supply pipe 6 to the filtration chamber 5 is filtered when passing through the filter membrane wall of each hollow system 61 of the hollow membrane filter module 4 from the outer surface to the inner surface. The water passing through the hollow system 61 is taken out separately from the upper and lower ends of the hollow system, and the filtered processing liquid 11 is discharged from the processing liquid chamber 7 to the outside via the processing liquid discharge pipe 8. In addition, 12 is an outlet valve provided in the processing liquid discharge pipe 8,
During normal filtration processing operation, this outlet valve 12 is kept open.

By the way, if v1 overtreatment operation is continued, filtered impurities will adhere to the surface of the hollow fiber membrane filter, and as the amount of impurities attached increases, the perturbation rate will decrease. The filter module 4 is subjected to regeneration processing.

As a method for regenerating the hollow fiber membrane filter module, there is a method of backwashing the hollow fiber membrane filter module using a treatment liquid, as described in, for example, Japanese Patent Application Laid-Open No. 60-19002. This backwashing method will be explained using the configuration shown in FIG. That is, the outlet valve 1 of the processing liquid discharge pipe 8
A backwashing air piping 13 is connected to the side of the closed container 1 than 2, and a check valve 14 and a stop valve 1 are connected to this backwashing air piping 13.
5, it is connected to a compressed air source.

On the other hand, a plurality of vent pipes 17, 17a... which communicate with the upper part of the filtration chamber 5 are connected to the airtight container 1.
8 and the backwash water waste discharge pipe 1 that communicates with the lower end of the filter 5
9 are provided, and these are connected to the tank 20. Note that the vent pipe 18 and the waste liquid discharge pipe 19 are provided with stop valves 21 and 22, respectively.

When performing regeneration processing by backwashing, first stop the supply of the treated liquid from the treated liquid supply pipe 6, close the outlet valve 12 of the treated liquid discharge pipe 8, and close the stop valve 20 of the vent pipe 17. Open. Note that the stop valve 21 of the waste liquid discharge pipe 18 is kept closed. In this state, the filtration chamber 5 is filled with the liquid to be treated, and the liquid to be treated is filled up to the part of the treatment liquid chamber 7, the treatment liquid discharge pipe 8, and the check valve 14 of the backwashing air pipe 13. 11 are fulfilled. From this state, the stop valve 15 of the backwash air pipe 13 is opened, and compressed air is supplied from the air storage tank 16 to the backwash air pipe 13. Backwash air piping 13
When compressed air is supplied from the check valve 14 side, the processing system 1
1, contrary to the filtration process, the processing liquid flows from the processing liquid chamber 7 side to the filter chamber 5 side from the inside to the outside of the hollow fiber membrane filter.

At this time, the crud attached to the outer peripheral surface of the hollow fiber membrane filter is peeled off by the processing liquid flowing back and falls to the bottom side of the filtration chamber 5. Due to such a backwash action, the processing liquid 11 flows back to the filtration chamber 5 side, and when the liquid level in the filtration chamber 5 increases, the weir 16, 16a of the closed container 1, which communicates with the vent pipe 17...
- Increased liquid flows out from the upper end and is stored in the tank 20 via the backwash vent pipe 18 and vent valve 21.

In addition, near the bottom of the filtration chamber 5, an air scrubbing device S is installed.
! 23 is provided, and air is supplied into the liquid to be treated 10 from an air supply device (not shown) via this air scrubbing device W123. Then, the outer peripheral surface of the hollow fiber membrane filter is further cleaned by the bubbling action.

In this way, when the regeneration action by backwashing and air scrubbing is completed, the stop valve 22 of the waste liquid discharge pipe 19 is opened, and the treated liquid 1O containing a large amount of crud is discharged from the lower part of the filtration chamber 5 into the tank 19. Discharge. After regeneration is performed in this manner, the stop valves 21, 22, 15 are closed and the outlet valve 12 is opened. Then, the liquid to be treated is again supplied from the liquid to be treated supply pipe 6 into the filtration chamber 5, and filtration processing via the hollow fiber membrane filter module 4 is performed.

(Problem to be Solved by the Invention) However, in the conventional hollow fiber membrane filtration device described above, when performing regeneration treatment by backwashing, a vent space is provided at the bottom of the tube plate in order to ensure a constant amount of backwash water and discharge rate. 25, and as the capacity of the hollow fiber membrane filtration device increases, the number of weirs 16 and backwash vent pipes 17 in the closed container 1 will be increased to ensure the necessary amount of backwash water and discharge speed. It becomes necessary to increase the amount.

As a result, a problem arises in that the number of hollow fiber membrane modules 4 that can be installed in the filtration chamber 5 is reduced, the effective membrane area due to the vent space 25 is reduced, and the filtration efficiency is deteriorated. In addition, there is a problem that air pockets are formed by air bubbles when ejected during backwashing, and the hollow fiber membrane comes into contact with air and deteriorates, impairing its integrity. As the diameter increases and the number increases, the piping configuration becomes larger.

A problem arises in that the scale of the equipment becomes excessive.

Furthermore, vent space 25. The existence of the weir 16 increases the fluid resistance, which limits the backwash line flow rate, and the rate of rise in the differential pressure as a filtration differential pressure characteristic of the hollow fiber membrane module 4 becomes faster, resulting in a shorter service life and, as a result, the module may be replaced at an earlier stage. Since it is necessary to replace it, a large amount of secondary waste is generated, and the increased frequency of replacement causes problems such as increased running costs.

The present invention has been made in view of these circumstances, and provides a hollow fiber membrane that can prevent contact between the hollow fiber membrane and air, thereby increasing the effective membrane area of the hollow fiber membrane and increasing the number of installed hollow fiber membrane modules. The purpose is to provide a filtration device.

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a sealed container, a tube plate that divides the inside of the sealed container into upper and lower parts, and a plurality of hollow fiber membrane modules suspended from the tube plate. At the bottom is the inlet pipe for the liquid to be treated.
In addition, in a hollow fiber membrane filtration device equipped with a treatment liquid outlet pipe at the top of a closed container, a backwash liquid discharge pipe is provided at the bottom of the closed container, and this backwash liquid discharge pipe is connected to the bottom surface of the tube plate once outside the closed container. This hollow fiber membrane filtration device is characterized in that it stands up to at least the same height.

(Function) In the hollow fiber membrane filtration device of the present invention, the backwash liquid that is being regenerated by backwashing does not need to pass through the weir, thereby eliminating pipe pressure loss due to the weir. As a result, the backwash line flow rate can be increased even at a predetermined backwash pressure, and backwash processing can be performed efficiently.

In addition, since there is no weir and the backwash liquid vent piping is raised above the tube plate of the filtration chamber partition, there is no vent space at the bottom of the tube plate, making it possible to completely immerse the entire hollow fiber membrane module in the liquid. Can be done.

Therefore, backwashing efficiency can be improved and the service life of the hollow fiber membrane can be extended. Furthermore, since the hollow fiber membrane module can be placed in the weir area, the amount of filtration can be increased, and since the backwash liquid vent piping can be integrated into one, equipment costs can be reduced, and economic efficiency can also be improved.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2.

The illustrated hollow fiber membrane filtration device is installed, for example, in a waste liquid system of a nuclear power plant, and FIG. 1 shows the main part of the device, and FIG. 2 shows the piping configuration of the entire device.

The inside of the tank-type airtight container 31 is partitioned into upper and lower parts by a horizontal tube plate 32, and U-shaped hollow fiber membrane filter modules 34 are suspended from a plurality of openings 33 in the tube plate 32 via housings 34a, respectively. are doing. The lower space of the closed container 31 in which the hollow fiber membrane filter module 34 is disposed is a filtration chamber 35, and a liquid to be treated supply pipe 36 and a backwash liquid vent pipe are provided in communication with each other in the lower part of the filtration chamber 35.

Note that the liquid to be treated supply pipe 36 is connected to a liquid to be treated tank 38 that accommodates the liquid to be treated 37 . A stop valve 39, a supply pump 40,
A flow regulating valve 41 and another stop valve 42 are provided.

On the other hand, the upper space above the tube plate 32 of the sealed container 31 is a processing liquid chamber 43, and this processing liquid chamber 43 has a processing liquid discharge pipe 4.
4 are connected in series. This processing liquid discharge pipe 44 is provided with an outlet valve 45 .

The liquid to be treated 37 supplied from the liquid to be treated supply pipe 36 to the filtration chamber 35 is filtered as it passes through each hollow fiber membrane filter wall of the hollow fiber membrane filter module 34 from the outer side to the inner side. The processing liquid 46 of the filter agent is stored in the processing liquid chamber 4.
3 to the outside via a processing liquid discharge pipe 44.

Next, the configuration of the backwashing device section will be explained.

A backwash air pipe 47 is connected to a portion of the treatment liquid discharge pipe 44 closer to the closed container 31 than the outlet valve 45, and a compressed air source is connected to the backwash air pipe 47 through a check valve 48 and a stop valve 49. Connected.

On the other hand, the closed container 31 is provided with a backwash liquid vent nozzle 51 that communicates with the lower end of the filtration chamber 35 and also serves as the to-be-processed liquid supply pipe 36. A liquid vent pipe 52 is provided upwardly and extends to a height that is the same as or higher than the lower surface of the tube plate 32 (a≧0). This backwash liquid vent pipe 52 is further bent downward to inject water into a waste liquid tank 57. Further, the backwash liquid waste discharge pipe 53 in the filtration chamber 35 of the closed container 31 is connected to a waste liquid tank 57 that branches off at the bottom of the rise of the backwash liquid vent pipe 52. In this device, a siphon-on break valve 56 is provided at the top of the backwash liquid vent pipe 52 to allow the filtration chamber 35 to be filled with the liquid to be treated at all times.

Note that the backwash liquid vent pipe 52 and the waste liquid discharge pipe 53 are provided with stop valves 54 and 55, respectively.

FIG. 4 shows another embodiment in which the liquid to be treated supply pipe 36, the backwash liquid vent pipe 52, and the waste liquid discharge pipe 53 are separated and independent, and the height of the downward takeout of the backwash liquid vent pipe 52 from the filtration chamber 35 is shown. The tube plate 32 is arranged at a level below the bottom surface of the tube plate 32.

Next, the backwashing action will be explained.

First, the supply of the liquid to be processed from the liquid to be processed supply pipe 36 is stopped, and the outlet valve 45 of the liquid discharge pipe 44 is closed.

In this state, the stop valve 54 of the backwash liquid vent pipe 52 is opened. Therefore, the backwash air pipe 4 is connected to the processing liquid in the processing liquid chamber 43.
7 is opened and compressed air is supplied to the backwash air pipe 47. Then, the treatment liquid is pressurized, and impurities adhering to the outer surface of the hollow fiber are peeled from the inside to the outside of the hollow fiber membrane and washed away. This backwashed processing liquid exits the nozzle 51 at the lower end of the I over chamber 35, passes over the top of the backwash liquid vent pipe 52, and only the processing liquid in the processing liquid chamber 43 is discharged, and flows into the waste liquid tank 57.

Thereafter, air for air scrubbing is further ejected from the air scrubbing device [58 to pulsate the hollow fiber membrane module 34, thereby peeling off impurities attached to the outer surface of the hollow fiber membrane.

Thereafter, the stop valve 55 is opened, and the backwash water containing impurities is discharged from the waste liquid discharge pipe 53 provided at the bottom of the closed container 31 to the waste liquid tank 57.

In the hollow fiber membrane filtration device according to this embodiment, the backwash liquid does not need to pass through the weir, so there is no pipe pressure loss due to the weir, and the backwash linear flow rate can be increased even at a predetermined backwash pressure. , backwashing can be performed efficiently.

Further, since there is no weir and the backwash liquid vent is outside the closed container 31, the entire hollow fiber membrane module can be completely immersed in the liquid without creating a vent space under the tube plate.

Therefore, backwashing efficiency can be improved and the service life of the hollow fiber membrane can be extended. In addition, since the area occupied by the hollow fiber membrane in the closed container 31 increases, the filtration system is improved and the backwash liquid vent piping can be unified, which reduces equipment costs and improves economic efficiency.

〔Effect of the invention〕

As described above, according to the present invention, the pressure drop in the backwash liquid vent piping can be reduced by eliminating the weir, and effective backwashing becomes possible, thereby increasing the service life of the hollow fiber membrane filter module. Furthermore, since no vent space is created at the bottom of the tube plate, the effective membrane area of the hollow fiber membrane module can be increased and the integrity can be ensured.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of essential parts showing an embodiment of the present invention, Fig. 2 is an overall configuration diagram, Fig. 3 is a sectional view showing a conventional example, Fig. 4 is a plan view of the conventional example, and Fig. 5 is a sectional view of a conventional example. A cross-sectional view showing a second embodiment of the present invention, FIG. 6 is a cross-sectional view of an engineered hollow fiber membrane module. 31... Airtight container, 32... Tube plate, 34...
... Hollow fiber membrane module, 35 ... Filtration chamber, 43 ... Processing liquid chamber, 4
4... Processing liquid discharge piping, 46... Processing liquid, 47.
... Air piping for backwashing, 52... Backwashing liquid vent piping,
56...Saifon break valve. Agent Patent Attorney Yudo Ken Chika Ken Daikomaru Figure 1 Figure 2 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] It is equipped with a sealed container, a tube plate that divides the inside of the sealed container into upper and lower parts, and a plurality of hollow fiber membrane modules suspended from the tube plate. In a hollow fiber membrane filtration device equipped with a treated liquid outlet pipe at the top, a backwash liquid discharge pipe is provided at the bottom of the sealed container, and this backwash liquid discharge pipe is temporarily installed outside the closed container at least at the same height as the bottom surface of the tube plate. This hollow fiber membrane filtration device is characterized by having been launched to date.