JPH10258221A - Filter element and filtration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the amount of trapped impurities after backwashing and to increase the processing capacity of a fluid to be purified when reusing the backwash after the impurities are captured and accumulated and the filter differential pressure rises. And a filter device having a small number of filter elements. SOLUTION: A spacer 2 is provided between filters 21 facing each other.
5 to prevent the deformation of the filter 21 due to the pressure acting on the surface of the filter 21 during backwashing,
Prevent impurities deposited on the surface from contacting each other,
In addition, a flow path for a fluid containing impurities that have been backwashed and separated is secured,
The impurities detached from the filter 21 can be easily discharged. Dummy element 3
0 is provided in the filtration device to reduce the number of filter elements 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter element and a filter device, and more particularly to improving the cleaning performance after capturing and depositing impurities, increasing the capacity for capturing impurities after reuse, and extending the life of the filter. The present invention relates to a filter element having a large processing capacity, which has improved economic efficiency, and a filtering device which has reduced the number of filter elements and has improved economic efficiency by using the filter element.

[0002]

2. Description of the Related Art A condensing system of a thermal power plant or a nuclear power plant is provided with a filtration device for removing impurities such as iron cladding. Conventionally used filter elements of a filtration device include a precoat type in which resin particles are precoated on the surface and a hollow fiber membrane type in which a large number of hollow fiber membranes are bundled.

[0003] The pre-coat type is inexpensive for the filter element, but requires a large amount of filtration equipment due to its small processing capacity, and has many piping systems, valves and containers, which is inefficient, and the iron clad removal rate is about 90%. And there is a problem that waste resin is generated at the time of back washing.

On the other hand, the hollow fiber membrane type has a large processing capacity,
Although the removal rate of iron clad is high at about 99% or more, there is a problem that the unit price of the filter element of the hollow fiber membrane module is high.

[0005] Against this background, recently, in the United States, a membrane filter type filter element in which a membrane filter is folded to increase an effective area per volume has been used.

[0006]

However, the above-mentioned known techniques have the following problems to be solved.

The filter element of the membrane filter type in which the effective area per volume is expanded by folding the membrane filter is conventionally used as a disposable, and it can be seen from the fact that the filter element is not backwashed and reused. Therefore, there is a problem that the removal amount of impurities is reduced to 10% or less of the initial amount when backwashing is repeated.

In particular, the iron cladding of a boiling water reactor has a strong adhesive property, and when backwashing is repeated, the amount of impurities removed sharply decreases, and the life of the filter element is short.

However, the filter element of the membrane filter type has a processing capacity between the precoat type and the hollow fiber membrane type, the removal rate of iron cladding is as high as 95% to 99% or more, and the filter element is inexpensive. Therefore, it is expected that if the backwashing performance can be improved, it will be most economical.

Accordingly, a first object of the present invention is to improve the cleaning performance after capturing and depositing impurities by using a membrane filter type filter element in which the effective area per volume is increased by folding the membrane filter. It is an object of the present invention to provide a filter element having a large impurity capture capacity after use, a long filter life, and improved economic efficiency.

In the case of newly manufacturing a filtration device, if the impurity capturing capacity of the filter element is increased by achieving the first object of the present invention, the number of filter elements per filtration device may be reduced or the filtration device may be reduced. By reducing the number, it is possible to realize a filtration device with improved economic efficiency.

However, when the filter element of the existing filtration device is replaced with a filter element having a larger impurity capturing capacity, the following problems occur.

That is, when all the filter elements in a certain filter are replaced with filter elements having a large impurity capturing capacity, it is not necessary to use all the filters in terms of capacity, and the number of filters can be reduced, and the cost is reduced. However, the flow rate of the fluid to be purified exceeds the design capacity of the piping system and the filtration device, and reliability cannot be ensured. On the other hand, if the total number of filter elements in a certain filtration device is replaced with a filter element having a large impurity capturing capacity and the whole filtration device is operated, the number of filter elements to be replaced is large and the economic efficiency is poor.

Therefore, a second object of the present invention is to reduce the number of filter elements in one filtration device by using a filter element having a large impurity capturing capacity in an existing total filtration device, thereby reducing the economical efficiency. An object of the present invention is to provide an improved filtration device.

[0015]

According to the first aspect of the present invention, a membrane filter is folded in a wave-like or bellows-like manner to increase the effective area per volume, and to deposit impurities on the filter. In a filter element in which impurities are backwashed and removed for reuse when the filter differential pressure increases, the pressure acting on the filter surface during backwashing between the folded and facing filter surfaces on the inflow side of the fluid to be purified. A spacer for preventing the deformation of the filter due to the above, preventing the impurities deposited on the facing filter surfaces from being folded and coming into contact with each other, and securing a flow path for the fluid containing the impurities that have been backwashed and separated. The filter element is provided.

In order to achieve the above object, according to a second aspect of the present invention, in the first aspect, the spacer is provided with a plurality of spacers spaced in the axial direction of the filter element and arranged in parallel with the inflow direction of the fluid to be purified. The filter element is characterized by comprising a wedge-shaped member and a thread-shaped member connecting these wedge-shaped members to each other.

According to a third aspect of the present invention, in order to achieve the above object, in the first aspect, the spacer is provided with a plurality of spacers which are arranged in the axial direction of the filter element in parallel with the inflow direction of the fluid to be purified. The filter element is characterized by comprising a rod-shaped member and a thread-shaped member connecting these rod-shaped members to each other.

According to a fourth aspect of the present invention, in order to achieve the above object, in the first aspect, the spacers are integrally connected in a circumferential direction of the filter element and are spaced apart in an axial direction of the filter element. The filter element is characterized by comprising a plurality of main members arranged in parallel to the flow direction of the fluid to be purified and auxiliary members for connecting these main members to each other.

According to a fifth aspect of the present invention, there is provided a filter element according to any one of the first to fourth aspects, wherein a material of each component of the filter element is incinerated like a plastic material including the spacer. It is characterized in that it is a filter element which is an easy material.

According to a sixth aspect of the present invention, there is provided a container, a separator disposed in the container, a plurality of filter elements connected to the separator, and an inflow pipe for supplying a fluid to be purified into the container. And an outflow pipe through which the purified fluid flows out of the container. In the filtration device for purifying the fluid to be purified through the filter element, a filter element having a larger processing capacity than the filter element is operated. When used as an exchange filter, the filter device is characterized in that the filter element is a filter device in which a part of the filter element is replaced with a dummy element having at least one end closed without a filter to prevent the fluid to be purified from flowing.

According to a seventh aspect of the present invention, there is provided a filter device according to the sixth aspect, wherein the filter element having a large processing capacity is the filter device according to any one of the first to fifth aspects. Features.

[0022]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIG. 1 to 7 show an embodiment of a filter element 20 according to the present invention.

As shown in FIG. 1, a filter element 20 according to an embodiment of the present invention is a membrane-shaped filter 2 having an effective area per volume expanded by being folded in a wavy or bellows shape.
1, a core 22 having a large number of flow paths 23, an outer protective cover 24 and a spacer 25,
Is composed of a wedge-shaped member 25a and a thread-shaped member 25b.

A feature of the present invention is that it has a spacer 25, and other components are the same as those of the filter element 20 according to the prior art. The component of the spacer 25 is a used filter element 2 such as plastic.
It is made of a material that can be easily reduced in volume by incineration.

During the cleaning operation, the fluid to be purified flows into the filter 21 from the outer periphery of the filter element 20,
Impurities such as iron clad are captured and removed on the surface of the filter 21. When the deposition amount of the impurities on the surface of the filter 21 increases, the pressure difference of the filter 21 increases. Therefore, the fluid is flowed in the direction of backwashing during the cleaning operation to remove and remove the impurities from the surface of the filter 21.

As shown in FIG. 2, the filter 21 comprises a filtration membrane 21a and protective films 21b, 21d and 21c, 21e before and after the filtration membrane 21a, as in the prior art.
The protective films 21b and 21d are mesh-like protective films, and the protective films 21c and 21e are film-like protective films having a larger flow path than the filtration film 21a. Protective film 21 on the inflow side of the fluid to be purified
In some cases, the protective films 21b and 21c may not be provided.

The effect of this embodiment will be described with reference to FIGS. FIG. 3A shows a filter element 20 according to the related art, and FIG. 3B shows a partial cross section of the filter element 20 according to the present embodiment and a state before and after cleaning. FIG. 10 shows a change in the amount of trapped impurities in a case where the cleaning operation and the backwashing are repeated, by comparing the prior art with the present invention.
In the prior art, several types of filter elements 20 tested have the highest impurity capture amounts.

In the prior art, when the purifying operation and the backwashing are repeated, the amount of trapped impurities rapidly decreases and reaches a steady state after the fourth to fifth times.
/ 10. When the power generation plant is used for a long time while repeating the purification operation and the backwashing, the steady values after the fourth to fifth times determine the amount of captured impurities and the life of the filter element 20.

The reason why the amount of trapped impurities in the prior art is greatly reduced will be described based on the disassembly analysis result of the filter element 20 with reference to FIG. Filter 21
When impurities are captured and deposited on the surface to form the impurity layer 29, the pressure difference of the filter 21 increases. Therefore, the fluid is caused to flow in the opposite direction (in the direction of the arrow) during the purification operation to remove the impurity layer 29. However, in this case, pressure acts on the filter 21 due to the flow of the fluid and the flow resistance of the impurity layer 29, and the filter 2
1 are deformed, and the impurity layers 29 deposited on the surface of the facing filter 21 are in contact with each other and are not effectively separated. Also,
Even when a part of the impurity layer 29 is detached, the outflow of the fluid containing impurities is inhibited, and the cleaning effect is significantly reduced.

In particular, since the iron clad in the condensate system of a boiling water reactor has strong adhesion, the cleaning effect is extremely low.
Only the tip of the filter 21 where the impurity layer 29 deposited on the surface of the filter 21 is not in contact with each other is removed. For this reason, when such backwashing is repeated several times, the trapped amount of impurities after backwashing is reduced to 1/10 or less of the initial value in a general filter element. Even the filter element having the highest impurity capture amount is reduced to about 1/10 of the initial value as shown in FIG.

In the present embodiment, as shown in FIG. 3B, even if a pressure acts on the filter 21 due to the flow of the fluid and the flow resistance of the impurity layer 29, the deformation of the filter 21 is prevented by the spacer 25. , Facing filter 21
The impurity layer 29 does not come into contact with most of the surface, and the impurity layer 29 can be effectively separated by backwashing. In addition, the wedge-shaped spacer 25 secures a flow path that expands in the flow direction of the backwashing fluid, so that the fluid containing impurities separated from the filter 21 can be easily discharged, and is effectively cleaned.

Therefore, in this embodiment, as shown in FIG. 10, even if the backwashing is repeated a number of times, the amount of trapped impurities after the backwashing does not significantly decrease. As a result, the amount of trapped impurities after reaching the steady value is about 5 times that of the prior art.
Increase by a factor of two.

As a general theory, the amount M of impurities trapped between one backwash and the next backwash is defined as follows: assuming that impurities are almost completely captured by the filter element 20, the inlet concentration C of impurities, It is proportional to the flow rate W and the backwash interval t and is expressed by the following equation.

M = C × W × t Since the inlet concentration C of the impurities is constant, the backwashing interval t becomes longer in the filter element 20 in which the amount M of the trapped impurities is large, and the life of the filter element 20 is lengthened. Alternatively, the number of filter elements 20 can be reduced by increasing the flow rate W of the fluid to be purified per one filter element 20, thereby improving the economic efficiency.

As described above, the function necessary for the spacer 25 is that the impurity layer 2 deposited on the surface of the filter
9 is to prevent the fluids 9 from coming into contact with each other, to secure a flow path through which the fluid containing impurities separated from the filter 21 can be easily discharged, and to effectively clean the fluid. Therefore, the shape of the spacer 25 is only required to satisfy these functions.

FIG. 4 shows an embodiment of the spacer 25.
The spacer 25 shown in FIG. 4A is the same as that shown in the embodiment of FIG. 1, and includes a wedge-shaped member 25a and a thread-shaped member 25b connecting these members. The feature of this embodiment is that the width of the wedge-shaped member 25a increases in the direction of increasing the flow rate of the fluid containing impurities at the time of backwashing, so that not only the discharge characteristics are improved, but also the fluid at this portion is improved. Since the flow resistance due to the flow is reduced, the fluid force effectively acts on the impurity layer 29, and is effective in separating the impurity layer 29. If plastic is used as the material of the spacer 25, for example, shaping and joining of parts are easy.

The spacer 26 shown in FIG. 4B is composed of a rod-like member 26a such as a cylinder or a prism, and a thread-like member 26b connecting these members. In order to secure a flow path of a fluid containing impurities at the time of back washing, a rod-like member 26a parallel to the flow direction is provided.
Is larger than the thread member 26b. A feature of this embodiment is that it is easy to manufacture.

The spacers 25 and 26 shown in FIG.
As shown in FIG. 2, if the filter elements 20 are connected by the connecting members 25c and 26c, the filter element 20 shown in FIG. 1 can be easily assembled. Further, the tip of the rod-shaped member 26a parallel to the flow direction (the left end in FIG. 5B) may be thinned. In this case, even in the filter element 20 shape shown in FIG. The generation of excessive stress can be prevented.

As shown in FIG. 6, the spacer according to the present invention comprises a main member 27a integrally formed with an auxiliary member 27b.
May be connected. If a plastic material is used, the main member 27a can be easily heat-molded, and the auxiliary member 2
7b is easy to join and connect.

Further, the shape of the filter 21 shown in FIG. 1 may be spiral as shown in FIG. 7. In this case, the surface area of the filter 21 is increased with the same outer diameter and one of the filter elements 20 is used. Per processing capacity can be increased.

As described above, in the filter element 20 according to the present invention, the spacer is provided between the facing filters to prevent the filter from being deformed due to the pressure acting on the filter surface during the backwashing. It is possible to prevent impurities deposited on the surface of the filter from coming into contact with each other, secure a flow path for a fluid containing impurities backwashed and separated, and easily discharge impurities separated from the filter surface. Therefore, the cleanability after capturing and accumulating impurities is improved, the impurity capturing capacity after reuse is dramatically increased, the filter life is prolonged, and the economy is improved.

That is, when a new filtration device is manufactured, the number of filtration towers containing a large number of filter elements 20 can be greatly reduced. For example, in a condensing filter of a 1,000,000 kW class nuclear power plant, about 10 filtration towers containing about 300 pre-coated filters are used. However, because the filter performance cannot be sufficiently exhibited, almost the same equipment is required. However, if the membrane filter type filter element 20 according to the present invention is used, the processing capacity per filter can be more than doubled,
The number of filtration towers can be reduced by half, and an extremely large economic effect can be obtained.

On the other hand, when the filter element 20 of the membrane filter type having a large processing capacity is used as an exchange filter of a filter in operation as in the present invention, the following problems occur. If the processing capacity is doubled, if only five of the ten filtration towers are used, the flow rate of the fluid to be purified per tower doubles, generally exceeding the design capacity of the piping system, etc., and impairing reliability. there is a possibility. On the other hand, if 10 filters are continuously used after replacing all the filters, a sufficient economic effect cannot be obtained. Accordingly, a second object of the present invention is to provide an economical filtration device that uses a small number of filter elements 20 having a large processing capacity, thereby reducing the replacement cost of the filter element 20 even in an existing filtration device. is there.

An embodiment of the present invention corresponding to the above-mentioned second object will be described below. 8 and 9 show an embodiment of the filtration device according to the present invention.

As shown in FIG. 8, the filtering apparatus of the present embodiment comprises a container 11, a separator 13 disposed in the container 11,
The support pipe 14 of the filter element 20, the upper support 12 of the filter element 20, the inflow pipe 16 for supplying the fluid to be purified into the vessel 11, the outflow pipe 17 from which the purified fluid flows out of the vessel 11, and the backwashing of the filter element 20. It comprises an air supply pipe 18 for supplying pressurized gas and a vent pipe 19, and a part of the filter element 20 is replaced by a dummy element 30 having no filter.

During the cleaning operation, the fluid to be purified is supplied to the inflow pipe 16.
After flowing into the container 11 and being purified by the filter element 20, it collects at the lower part of the container 11 and flows out from the outflow pipe 17. As a result of the cleaning operation, impurities are removed from the filter element 20.
When the differential pressure rises, the flow of the fluid to be purified is stopped and the cleaning is performed. At the time of cleaning, pressurized gas is supplied from the air supply pipe 18 to form a pressurized gas layer below the separator 13, and the purified water in this portion is caused to flow back to the filter element 20 via the support pipe 14, and adhered. The impurities thus removed are removed from the inflow pipe 16. The supplied pressurized gas is supplied to the vent pipe 10
Exhaust from Since a part of the filter element 20 is replaced by an inexpensive dummy element 30 having no filter, the number of filter elements 20 can be significantly reduced, and the replacement cost of the filter element 20 can be reduced.

In this case, the pressurized gas supplied at the time of cleaning flows into the dummy element 30 and accumulates in the dummy element 30, which causes a change in the flow rate of the fluid to be purified during the cleaning operation. As shown in (1), at least one end of the dummy element 30 is closed. The dummy element 30 shown in FIG. 9A has a rod shape, and does not allow fluid to flow therein. The dummy element 31 shown in FIG.
Is cylindrical, but one end is closed, so that pressurized gas does not flow. The other end is open
This is to prevent the dummy element 31 from being crushed by an external pressure. The filter element 20 according to the present embodiment includes a filter element 2 according to the present invention.
Any filter element 20 having a large processing capacity other than 0 may be used.

[0048]

According to the present invention, since the spacer is provided between the facing filters, the deformation of the filter due to the pressure acting on the filter surface during the backwashing is prevented, and the impurities deposited on the facing filter surface are removed. It is possible to prevent the impurities from coming into contact with each other, to secure a flow path for the fluid containing the backwashed and separated impurities, and to easily discharge the impurities separated from the filter surface. Therefore, the cleanability after capturing and accumulating impurities is improved, the impurity capturing capacity after reuse is dramatically increased, the filter life is prolonged, and the economy is improved. That is, when manufacturing a new filtration device, the number of filtration towers incorporating a large number of filter elements can be significantly reduced.

Further, by mixing a filter element having a large processing capacity and an inexpensive dummy element having one end closed in a filtration tower, the number of filter elements can be reduced even in an existing filtration device, and the number of filter elements can be reduced. An economical filtration device with reduced replacement costs can be provided.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a detailed structure of a filter element according to a first embodiment of the present invention.

FIG. 2 is a partial sectional view showing a detailed structure of a filter portion of the filter element shown in FIG.

FIG. 3 is a conceptual diagram comparing the cleaning effect of the filter element shown in FIG. 1 with a conventional technology.

FIG. 4 is a partial cross-sectional view illustrating a detailed structure of a spacer shown in FIG. 1 and a modified example thereof.

FIG. 5 is a partial cross-sectional view showing an assembled state of the spacer shown in FIG. 1 and a modified example thereof.

FIG. 6 is a partial sectional view showing a detailed structure of another spacer according to the present invention.

FIG. 7 is a partial sectional view showing the detailed structure of another filter element according to the present invention.

FIG. 8 is a longitudinal sectional view illustrating a structure of a filtration device according to a second embodiment of the present invention.

9 is a partial longitudinal sectional view showing a detailed structure of a dummy element shown in FIG.

FIG. 10 is a graph showing a change in the amount of trapped impurities in a case where the cleaning operation and the backwashing are repeated, comparing the prior art and the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 ... Container 12 ... Upper support 13 ... Separator 20 ... Filter element 21 ... Filter 25 ... Spacer 26 ... Spacer 27 ... Spacer 28 ... Spacer 29 ... Impurity layer 30 ... Dummy element 31 ... Dummy element

Claims (7)

[Claims] An effective area per volume is expanded by folding a membrane filter in a wave-like or bellows-like manner, and when impurities accumulate on the filter and a filter differential pressure increases, impurities are backwashed and removed for reuse. In the filter element, the filter is prevented from being deformed due to the pressure acting on the filter surface at the time of backwashing, between the folded and facing filter surfaces on the inflow side of the fluid to be purified, and the folded filter surface is disposed on each facing filter surface. A filter element comprising a spacer for preventing accumulated impurities from coming into contact with each other and for securing a flow path for a fluid containing backwashed and separated impurities. 2. The spacer comprises a plurality of wedge-shaped members arranged at intervals in an axial direction of the filter element and parallel to an inflow direction of a fluid to be purified, a thread-shaped member connecting these wedge-shaped members to each other, 2. The filter element according to claim 1, wherein the filter element comprises: 3. The spacer comprises: a plurality of rod-shaped members arranged in parallel with a flow direction of a fluid to be purified, spaced apart in an axial direction of a filter element; a thread-shaped member connecting these rod-shaped members to each other; 2. The filter element according to claim 1, wherein the filter element comprises: 4. A plurality of main spacers, which are integrally connected in the circumferential direction of the filter element, and are spaced apart in the axial direction of the filter element and arranged in parallel with the inflow direction of the fluid to be purified. The filter element according to claim 1, comprising a member and an auxiliary member for connecting these main members to each other. 5. The material of each component of the filter element is a material that can be easily incinerated, such as a plastic material, including the spacer.
5. The filter element according to any one of claims 1 to 4. 6. A container, a separator disposed in the container, a plurality of filter elements connected to the separator, an inflow pipe for supplying a fluid to be purified into the container, and an outflow through which the purified fluid flows out of the container. A filter element for purifying the fluid to be purified through the filter element, wherein the filter element having a larger processing capacity than the filter element is used as a replacement filter of the filtering apparatus in operation. A filtering device, wherein a part is replaced by a dummy element which is not provided with a filter and at least one end of which is blocked so that a fluid to be purified does not flow. 7. A filtering device according to claim 6, wherein the filter element having a large processing capacity is the filter element according to any one of claims 1 to 5.