JPH09187605A - Pleat cartridge filter and fitter for power plant condensate system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inexpensive, disposal pleat cartridge filter having simple structure as a prefilter of a condensate desalination device in a condensate system of a thermal power plant. SOLUTION: A pleat type filter body in which a flat plate-shaped filter sheet is folded in pleats to form it into a cylinder is arranged around a water collecting core of a central part. The filter body 7 having laminated structure consisting of a second layer 702 consisting of a filter membrane having filter action to suspended matter as the inner surface of the cylinder and a first layer 701 consisting of coarse nonwoven fabric in which there is essentially no filter action to the suspended matter as the outer surface of the cylinder. Besides, the average folded pitch in the circumferential direction in a folded part on the cylinder inner edge side of the filter body is 2.5mm, and the thickness of the filter layer is 200μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pleated type cartridge filter, a filter device which is installed in a condensate demineralizer in a condensate system of a thermal power plant or a nuclear power plant using the pleated cartridge filter, and an existing precoat filter. The present invention relates to a renewal method for changing a filter of a filter device such as a thermal power plant installed therein to a filter which is advantageous in operation.

[0002]

2. Description of the Related Art Conventionally, for example, in a once-through plant of a thermal power plant, in a condensate system in which steam that drives a turbine is returned to water by a condenser and resupplied to the boiler, impurities that adversely affect the boiler are ion-exchange resin. A condensate demineralizer is installed to remove the suspended matter, and a suspended matter removal filter is installed to prevent the suspended matter from adhering to the surface of the ion exchange resin and lowering the ion exchange capacity. ing.

A precoat filter or an electromagnetic filter is used as a filter of the above-mentioned filtering device placed in front of the condensate demineralizer, and most of the suspended substances in the electromagnetic filter are magnetic substances such as iron. For this reason, it is a method of magnetically separating it from the liquid, but there is a problem that the facility cost is high and particularly when changing the existing facility, a large amount of cost is required. For this reason, a precoat filter having a structure in which the surface of a cylindrical porous element is coated with a filtering agent for filtering suspended solids has been widely used as a filter.

FIG. 6 shows an example of the general construction of a general precoat filter type filtering device which is placed in front of a condensate demineralizer of a condensate system, and shows a condenser (not shown). Condensed water made from steam is passed from a condensate recovery tank 100 to a condensate filter (filtering device) 103 by a condensate pump 102 through a condensate line 101 to retain a filter agent on the surface of an element 104 in a precoat. After removing suspended solids (mainly iron) with a filter, the treated water line 105
Is sent to the condensate treated water tank 106, and further to a condensate demineralizer (not shown) in the subsequent stage.
A precoat device for precoat filter agent is attached to this facility. That is, this pre-coating apparatus uses the pre-coat return line 107 during pre-coating.
From the element 1 above, a new filtering agent is added to the circulating flow returning from the precoat tank 108 to the precoat tank 108 by the precoat pump 109.
04 is supplied to the surface. Further, since it is necessary to keep the filtering agent on the surface of the element 104, it is necessary to always pass water, and for this purpose, a circulation system passage 110 for returning the treated water to the upstream side of the condensate pump 102 is provided. ing.

[0005]

In the system using the precoat filter as a filter as described above, a regular precoat operation is required, and accordingly, a precoat device and a wastewater treatment facility are indispensable. In addition, it is necessary to regularly clean and replace the element, and as a problem in operation, it is necessary to always pass water to retain the filter agent on the element, and the time required for precoating is not always short. Since it is not present, there is a drawback that the down time becomes long, and the improvement is required.

By the way, generally known as a filter is a so-called disposable type cartridge filter, which is characterized in that it does not require passage of water for retaining a filtering agent and can be immediately restarted by replacement. If these advantages not found in filters and electromagnetic filters are utilized, it can be said that the filter is suitable as the condensate filter. But,
Cartridge filters have the major drawback of low ability to remove suspended solids and particularly short operating life, so they are used for filtration devices used in condensate systems such as thermal power plant once-through plants, which require industrial continuous operation for a long time. It is not suitable as a filter and has never been used.

In view of the conventional problems as described above, the present inventor has obtained the advantages that the cartridge filter does not need to pass water for retaining the filtering agent and that it can be immediately restarted by replacement. Moreover, we have conducted intensive research to develop a filter that can satisfy the excellent filtration performance and filter membrane life of the precoat filter, especially a new filter suitable as a filter for a condensate system of a once-through plant of a thermal power plant. It was

In the process, a pleated filter classified as a cartridge filter is equipped with a pleated filter in which a flat plate-shaped filter sheet is folded in a pleated shape and the whole is formed into a cylindrical shape. , A second layer consisting of a filtration membrane having a function of filtering suspended matter facing the central water collecting core side, and a coarse mesh having a substantially non-filtering effect on suspended matter facing the outer side of the cylinder A first layer of a non-woven fabric (hereinafter sometimes abbreviated as "coarse non-woven fabric") and a non-woven fabric for securing water permeability on the back side of the filtration membrane, for example, may be abbreviated as "back-coarse non-woven fabric". ), And the filtration area is given by the fold amount (width) and the number of folds of pleats, which are radial dimensions, if the axial dimension is constant. Increase the folding amount or fold It was examined in detail by paying attention to that there is a possibility to extend the enhanced especially membrane life of filtration capacity by increasing the.

However, if the folding amount is increased, the diameter of the filter module becomes large, and in the condensate system of a thermal power plant where several tens to several hundreds of cartridge filters are installed, the tower of the filter device is significantly large. However, it is not suitable because it becomes large in size, and in particular, there is a problem that it is not possible to replace the precoat filter of the existing equipment with this because of the limitation of the volume of the existing equipment. On the other hand, if the number of folds is increased, the filtration membrane area can be increased without increasing the volume of the cartridge. However, in this method, although the filtration area is apparently increased, the number of folds is simply increased. Even if the pleats are folded in a radial shape with pleats, the actual effective filtration surface will be reduced due to poor water flow, especially at the cylindrical inner edge, and as a result, the effect of extending the operating life cannot be obtained. The problem is discovered. Therefore, the above problem cannot be solved by simply increasing the folding amount or the number of folding mountains.

From the above, the present inventor intends to increase the filtering area by increasing the number of folding ridges in the conventional pleat type filter, and to generate the pleats at the inner edge portion of the pleat as the number of folding folds increases. The present invention has been accomplished by studying a method of reducing a region of poor water flow as much as possible.

That is, in a conventional pleat-type cartridge filter having an outer diameter of about 150 mm and a folding number of about 90, a laminated first-layer pre-filter having a function as a prescreen in a tubular pleat-type filter is used. The coarse non-woven fabric layer made of melt blown (which is the same as what is conventionally called "micro spun bond" or "spun bond") that can be called a filter has a spacer function to ensure uniform water flow to the filtration membrane. And the function of holding and fixing the cake layer formed on the surface of the filtration membrane of the second layer, but the influence of the layer thickness has not been particularly studied. However, if the number of folding ridges is increased to 100 or more without changing other configurations, as described above, there is a tendency for the area of poor water flow to suddenly expand, particularly at the inner edge portion of the pleat, which causes the meltblown. It came to discover that it is correlated with the thickness of.

The present invention has been made on the basis of such knowledge, and its purpose is the convenience of operation that the precoat filter does not require constant water flow and can be immediately restarted by replacement. It is an object to provide a cartridge filter that satisfies the above requirements and has excellent filtration performance and filter membrane life.

Another object of the present invention is to use this cartridge filter as a filter in front of a condensate demineralizer of a condensate system in a power plant such as a thermal power plant so that the structure is simple and inexpensive. There is a filter device that can realize various condensate system equipment.

Still another object of the present invention is a cartridge filter which can be replaced by a condensate system of an existing thermal power plant equipped with a precoat filter and which enables easy replacement work. It is in the place of providing.

[0015]

One of the features of the pleated cartridge filter according to the present invention that achieves the above-mentioned object is that a vertical cylindrical water collecting core at the center and a periphery of the water collecting core are provided. A pleated filter body that is arranged and has a flat plate-like filter sheet that is folded in a radial direction into a pleated shape and has a tubular shape. A first layer comprising a coarse non-woven fabric (hereinafter abbreviated as “coarse non-woven fabric”) having substantially no filtering action on suspended matter; and a second layer comprising a filtration membrane having a filtering action on suspended matter, In a pleated cartridge filter provided in a laminated structure with a third layer that ensures water permeability on the permeate side that has passed through a filtration membrane, the filtration body formed into a tubular shape by folding a filtration sheet is a tubular shape. At the inner edge of the fold 1.2m average folding pitch of direction
m-2.5 mm, preferably 2.2 mm-2.5 mm,
The thickness of the first layer is 200 μm to 400 μm, preferably 300 μm to 400 μm, and the total thickness of the filter sheet in the natural state is ½ of the average folding pitch.
It is thinner than the above and preferably has a total thickness having voids of 50 μm or more.

In the above description, the average folding pitch of the folds in the cylinder circumferential direction at the folds on the cylindrical inner edge side of the filter is:
The larger the number, the smaller the number of folds and the smaller the filtration area, which tends to shorten the service life.
If the average folding pitch is less than 1.2 mm, the filter material becomes thin, which is difficult to manufacture because it is not suitable for industrial use. Therefore, the above range is set.

The thickness of the first layer made of coarse non-woven fabric is
If it is less than 200 μm, 20% or more of the membrane surface will not pass water, which is inefficient, and if it exceeds 400 μm, the filter material will be thick and the fold pitch will be large, resulting in folding. It is not appropriate because it is inefficient because the number of mountains cannot be large. Therefore, the above range is set.

In the filter body thus constructed, the coarse nonwoven fabric constituting the first layer is not limited, but may be melt blown (as described above, "micro spun bond" or "spun bond"). The fiber diameter of the fibers (generally synthetic resin fibers such as polypropylene fibers) constituting the nonwoven fabric is 20 to 80 μm, in addition to the above range.
Nonwoven fabric basis weight 50-150 g / m ² , mesh opening 60-2
Those having a size of 50 μm are preferably used. Although the fiber diameter and the basis weight are influenced by the pitch of the folds, they are related to the crush resistance and water permeability of the first layer due to the surface pressure, and are mainly generated in the inner edge of the pleat. In order to make the water-poor portion as small as possible and to make the effective utilization rate of the membrane surface (permeated water permeation area / total membrane area) 80% or more, preferably 100%, the above ranges are set to extend the life. Is often preferred for this. Further, the size of the openings is preferably such that the space for the flow path can be maintained between the surfaces of the filtration membrane (second layer) within the range where the suspended matter is not removed. In many cases. In the present specification, the term “melt blown” refers to a material produced by directly forming a web from polymer fibers as a raw material. As the non-woven fabric, there are other non-woven fabrics manufactured by a wet bonding method or a wet process. Even if the non-woven fabrics are manufactured by these methods, any non-woven fabric can be used without limitation as long as it satisfies the above-mentioned conditions.

The filtration membrane forming the second layer of the pleated filter used in the present invention is not limited, but it is a filtration membrane made of a nonwoven fabric of synthetic resin fiber, generally a conventional pleated filtration. The same filtration membrane as that used in the body can be used, and if necessary, a filtration membrane having a filtration capacity capable of satisfying the quality of filtered water required depending on the application can be used. Specifically, for example, when used as a filter in front of a condensate demineralizer in a condensate system of a thermal power plant, in order to achieve an iron removal rate of 80% or more, preferably 85% or more, the average pore diameter is 2 to 10 μm or less, preferably 3 to 8 μm or less is desirable. Average pore size is 1
If it exceeds 0 μm, the iron removal rate will be less than 80% and the quality of filtered water will be poor. On the contrary, if the average pore size is less than 2 μm, the limit amount of captured iron (captured iron: the specified amount of iron will not interfere with the operation of the equipment). The amount of iron that can be captured by filtration within the range of the filtration differential pressure that is allowed when a condensate flow rate is flown. It depends on the equipment, but generally it is the amount of iron that can be captured before the filtration differential pressure rises by 1 kgf / cm ^2. Is often shown)
The operating life will be shortened.

The thickness of the second layer composed of this filtration membrane is not particularly limited, but is generally 200 to 600.
μm, preferably 300 to 500 μm is desirable.

In the present invention, the third layer, which is laminated with the first layer made of the coarse nonwoven fabric and the second layer made of the filtration membrane, secures a passage for the permeated water of the filtration sheet and improves the structural strength of the filtration sheet. It is provided for reinforcement, and if the requirements can be satisfied and the total thickness of the filter sheet can be maintained within the above range, the structure, the material, etc. are adopted without limitation, and the net-like one is used. Or the same as the above-mentioned coarse nonwoven fabric of the first layer (hereinafter sometimes referred to as “backside rough nonwoven fabric”), or more simply, the first layer and the third layer have exactly the same construction and sandwich a filter membrane. You can also A preferable thickness is about 200 to 400 μm.

In the filter sheet having the three-layer structure forming the filter body as described above, when the total thickness of the flat plate-like filter sheet forming the filter sheet is in a natural state (state before folding in a pleated shape),
It is set to 1/2 or less of the average folding pitch of the above-mentioned filter, and is generally 600 to 1250 μm, preferably 70.
It is often preferable that the thickness is 0 to 1250 μm. Further, the three-layer structure may be manufactured by separately manufacturing each layer and adhering or simply laminating it, or may be manufactured as an integral one having a layer structure.

The pleated cartridge filter of the present invention can be suitably used as a filter for a filter device in front of a condensate demineralizer in a condensate system of a thermal power plant, but is not limited thereto. Instead, it can be used as a filter for a filter device in front of the condensate demineralizer in the condensate system of a nuclear power plant, and is also useful as a long-life filter for applications other than power plants. is there.

The pleated filter according to the present invention is not limited to the one in which the filter body is cylindrically arranged around the cylindrical core, and may have another structure. The filter body may be arranged in a cylindrical shape, but the general cartridge filter to which the present invention is applied is not limited, but an outer diameter of 50 mm to
A typical example is a circular shape having a length of 150 mm and a length of 250 mm to 1000 mm.

According to the present invention, a condensate filter of an existing thermal power plant equipped with a precoat filter is used as a disposable type cartridge having a substantially equal module size with low cost and easy work. You can update the filter.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 shows an outline of the construction of a pleated filter 1 which is a pleated cartridge filter constructed according to the present invention, and FIG. Fig. 3 is a partially expanded view of the body, Fig. 3 is a partially horizontal cross-section of this filter, and Fig. 5 is a filter in front of the condensate desalination device of the condensate system of a thermal power plant. As a device 50, a flow diagram shows an example of a configuration outline in which this filter is mounted. In these figures, 2 is a cylindrical protector made of stainless wire mesh for protecting the outer circumference, and an end plate 4 is attached to the lower end of the protector to close it, and an end plate 3 is attached to the upper end thereof. The treated water (condensate), which is suspended from the partition plate 501 of the filtering device (condensate filter) 50 shown in FIG. 5 by fastening means (not shown) and is supplied to the lower chamber of the partition plate 501, It is provided so that water can be passed through the filter 1 to the upper chamber of the partition plate 501.

Reference numeral 5 denotes a water collecting core provided in the center, to which a reinforcing ring 6 is assembled, and a pleated filter body 7 is arranged in a cylindrical shape around the reinforcing ring 6 as shown in FIG. There is. The upper and lower ends of this pleated filter body 7 are
The inside and outside of the cylinder are watertightly sealed by the adhesive seal 8.

In the present embodiment, the pleated filter body 7 has a first layer 701 made of a coarse nonwoven fabric, as shown in FIG.
It is provided so as to form a three-layer laminated structure of a second layer 702 made of a filtration membrane and a third layer 703 made of a rough back surface nonwoven fabric.

Embodiment 2 In this embodiment, as shown in FIG. 5, a filter device (condensate filter) 50 equipped with a pleated filter (cartridge filter) 1 according to the present invention is used as a condensate system of a thermal power plant. 2 shows an example provided as a filter in front of the condensate demineralizer of FIG.

In the example of FIG. 5, the condensate converted from steam by a condenser (not shown) is passed through a condensate pump 102 to a condensate filter (filtering device) 50 through a condensate line 101. After being hydrated and removing suspended substances (mainly iron content) with the pleated filter 1, the effluent is sent from the treated water line 105 to the condensate treated water tank 106, and further condensate demineralizer (not shown) at the subsequent stage. It is supposed to be sent to.

This equipment does not require the precoat device for the precoat filter agent described with reference to FIG. 6 and does not require constant water flow for keeping the filter agent on the surface of the element. It is unnecessary and, as can be seen from the comparison with FIG. 6, the structure thereof is extremely simple and simple as compared with the filtration equipment using the precoat filter as a filter.

[0033]

【Example】

Examples 1 and 2 and Comparative Examples 1 to 3 The basic configuration of the apparatus shown in FIG. 5 is configured under the following conditions, and the configuration of the filter body 7 is set under various conditions as shown in Table 1 below. The filtration performance and filtration life were examined.

The filtration test conditions and measurements are as follows.

(Filtration Test Conditions) 1 of a pleat type cartridge filter having a filter body 7 having the constitution shown in Table 1 below.
The book is used to configure the condensate filter 50 shown in FIG.
Condensate from thermal power plant is treated water as treated water flow rate 0.75m
Filtration was performed at ³ / h.

The filtration life is calculated from the limit trapped iron amount until the filtration differential pressure rises by 1 kgf / cm ² by measuring the relationship between the iron amount trapped by the pleated cartridge filter and the filtration differential pressure with the progress of filtration. Then, the relative value was evaluated when the limit trapped iron amount of Comparative Example 1 which is a conventional filter specification is 1 (130 gas Fe / filter) (life ratio 1 is thermal power generation with a condensate iron concentration of 10 ppb level at normal time). It corresponds to approximately one year of water passing through the place.) Note that the amount of trapped iron is obtained by multiplying the water flow rate and the water passing time by the concentration obtained by subtracting the iron concentration at the outlet from the iron concentration at the inlet of the condensate filter 50. Although it was measured, the iron concentration in the condensate also fluctuates depending on operating conditions (for example, 5
ppb to 100 ppb), so it was determined by accumulating the values calculated by dividing each suitable period. The average iron removal rate during this period satisfied the target value of 80% in each of Examples 1 and 2 and Comparative Examples 1 to 3.

Further, the effective membrane utilization rate is as follows. It is a surface that can be measured because of very little dirt, and is observed as concentrated on the filtration surface near the folded portion on the side close to the core 5) Calculated as the ratio of the area subtracted from the filtration area did.

The results are shown in Table 1 below.

[0039]

[Table 1]

The results of this filtration test show the following.

In the conventional general filter of Comparative Example 1, the effective utilization rate of the membrane surface was 80%, but the filtration life was short. It is considered that this is because the film area is insufficient.

In Comparative Example 2, a filter body having substantially the same structure as that of Comparative Example 1 except that the number of folding ridges was set to 100 (however, the fold pitch becomes smaller as the number of folding ridges increases) was obtained, and therefore, apparently. Although the film area of No. 1 increased by about 11%, the effective utilization of the film surface decreased to 60%, and as a result, the life was shorter than that of Comparative Example 1.

In Comparative Example 3, a filter body having a thickness of the first layer increased by 40 μm to 150 μm as compared with the filter body of Comparative Example 2 was used. However, it was equal to or less than that of Comparative Example 1 and was insufficient.

In Example 1, the thickness of the first layer was further increased by 150 μm as compared with the filter body of Comparative Example 3 to obtain 300 μm.
When a filter with m was used, the effective utilization of the membrane surface was 10
It was 0%, which was an excellent result that the life was dramatically extended to twice as long as that of Comparative Example 1.

In Example 2, when the number of folding ridges was increased by 110, about 10%, as compared with Example 1, 100% effective utilization of the film surface was maintained and the life was 2.4 times that of Comparative Example 1. Excellent results have been obtained with further extension.

The correlation between the effective utilization rate of the membrane surface and the thickness of the first layer of the filter obtained from the above results was calculated by using the number of folds of 100.
The above is shown in FIG.

From FIG. 4, it can be seen that the membrane surface effective utilization rate of 80%, which has been generally required for the pleat type cartridge filter, can be achieved by setting the thickness of the first layer of the filter body to 200 μm or more. That is, it can be understood that when the first layer has a thickness of 200 μm or more, it is possible to ensure that the water to be treated flows to the vicinity of the core side of the pleated cartridge filter, and the filtration membrane can be effectively used.

[0048]

EFFECTS OF THE INVENTION According to the present invention, the cartridge filter is equivalent to the conventional pre-coated filter in that it does not require water passage for holding the filtering agent and can be immediately restarted by replacement. There is an effect that it is possible to provide a cartridge filter that can satisfy the excellent filtration performance and the life of the filtration membrane.

Further, by using this cartridge filter as a filter in front of the condensate demineralizer in the condensate system of the once-through plant of a thermal power plant, there is an effect that the facility of the condensate system can be made extremely simple. .

Further, in the condensate system of an existing thermal power plant once-through plant equipped with a precoat filter, the effect that the cartridge filter of the present invention can be adopted in place of the precoat filter is also obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a filter which is a pleated cartridge filter of the present invention.

FIG. 2 is a partially exploded cross-sectional view of the filter of FIG. 1 showing a pleated filter.

FIG. 3 is a view showing the filter of FIG. 1 in a partially horizontal section.

FIG. 4 is a diagram showing the relationship between the effective utilization rate (%) of the film surface and the size of the layer thickness of the rough nonwoven fabric of the first layer shown in the constitution of the present invention.

FIG. 5 is a flow chart showing an example of a configuration outline in which a pleated filter of the present invention is mounted as a filter device in front of a condensate demineralizer of a condensate system of a thermal power plant.

FIG. 6 is a flow chart showing an example of a schematic configuration of a filter device in front of a condensate demineralizer in a condensate system of a thermal power plant using a conventional precoat filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pleated type filter, 2 ... Cylindrical protector, 3,4 ... End plate, 5 ... Filtration device, 501 ... Separator plate, 6 ... Reinforcement ring, 7 ... Pleated filter, 701 ... First layer made of coarse nonwoven fabric, 702 ... Second layer made of filtration membrane, 703 ... Third layer made of coarse nonwoven fabric, 8 ... Adhesive seal, 50 ... Filtration device (condensate filter), 501 ... Separator plate, 100 ... Condensate recovery tank, 101 ... Condensate line, 102 ... Condensate pump, 103 ... Filtration device ( Condensate filter), 104 ... Element, 105 ... Treated water line, 106 ... Condensate treated water tank, 107 ... Precoat return line, 108 ... Precoat tank, 109 ... Precoat pump .

Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location B01D 35/02 Z

Claims (10)

[Claims] 1. A pleated type tube having a vertical cylindrical water collecting core in a central portion and a flat plate-shaped filter sheet arranged around the water collecting core and folded in a radial direction in a pleated shape. A filter sheet comprising a filter body, the filter sheet comprising: a first layer made of a coarse non-woven fabric having substantially no filtering effect on suspended matter in the water to be treated that flows from the outside to the inside of the cylinder; A pleated-type cartridge filter provided with a laminated structure of a second layer composed of a filtration membrane having a filtering action on a substance and a third layer for ensuring water permeability on the permeate side through the filtration membrane, comprising: The filter body, which is folded and formed into a tubular shape,
The average folding pitch in the cylinder circumferential direction at the fold portion on the inner edge side of the cylinder is 1.2 mm to 2.5 mm, the thickness of the first layer is 200 μm to 400 μm, and the total thickness of the filtration sheet in the natural state is the above. Pleated cartridge filter characterized by being thinner than 1/2 of the average folding pitch. 2. The non-woven fabric for forming the first layer according to claim 1, which is a synthetic fiber non-woven fabric having a fiber diameter of 20 to 80 μm and a non-woven fabric weight of 50 to 150 g / m 2.
^2. A pleat type cartridge filter having an opening of 60 to 250 μm. 3. The pleated cartridge filter according to claim 1 or 2, wherein the average folding pitch of the filter body is 2.2 mm to 2.5 mm. 4. The method according to claim 1, wherein
The thickness of the first layer of the filter sheet constituting the filter is 30
A pleated cartridge filter having a thickness of 0 μm to 400 μm. 5. The method according to claim 1, wherein
A pleat-type cartridge filter characterized in that a non-woven fabric having a coarse mesh, which is a first layer of a filter sheet constituting a filter body, is a melt blown one. 6. A pleat type tube having a vertical cylindrical water collecting core in a central portion and a flat plate-shaped filter sheet arranged around the water collecting core and folded in a radial direction in a pleated shape. A filter sheet comprising a filter body, the filter sheet comprising: a first layer made of a coarse non-woven fabric having substantially no filtering effect on suspended matter in the water to be treated that flows from the outside to the inside of the cylinder; A pleated type cartridge filter provided in a laminated structure of a second layer formed of a filtration membrane having a filtering action on a substance and a third layer for ensuring water permeability on the permeate side that has passed through the filtration membrane. Means that the total thickness of the filter sheet constituting the filter body is 1/2 of the average folding pitch in the natural state.
A pleated cartridge filter characterized by being thinner than the above and having the following structure: A pleated average folding pitch in the cylinder circumferential direction in the fold portion on the inner edge side of the cylinder is 1.2 mm to 2.5 mm: The thickness of the first layer of the filter sheet constituting the filter is 20
0 μm to 400 μm: The thickness of the second layer of the filter sheet constituting the filter is 20.
0 μm to 600 μm: The thickness of the third layer of the filter sheet constituting the filter is 20.
0 μm to 400 μm: In the natural state, the total thickness of the first to third layers is 60.
0 μm to 1250 μm. 7. A pleated type having a central cylindrical vertical water collecting core and a flat filter sheet arranged around the water collecting core and folded in a radial fold into a cylindrical shape. A filter sheet comprising a filter body, the filter sheet comprising: a first layer made of a coarse non-woven fabric having substantially no filtering effect on suspended matter in the water to be treated that flows from the outside to the inside of the cylinder; A pleated type cartridge filter provided in a laminated structure of a second layer formed of a filtration membrane having a filtering action on a substance and a third layer for ensuring water permeability on the permeate side that has passed through the filtration membrane. Means that the total thickness of the filter sheet constituting the filter body is 1/2 of the average folding pitch in the natural state.
A pleated cartridge filter which is thinner than the above and has the following configuration: A fold-shaped average folding pitch in the cylinder circumferential direction in the fold portion on the inner edge side of the cylinder is 2.2 mm to 2.5 mm: The thickness of the first layer of the filter sheet constituting the filter is 30
0 μm to 400 μm: The thickness of the second layer of the filter sheet constituting the filter is 20.
0 μm to 600 μm: The thickness of the third layer of the filter sheet constituting the filter is 20.
0 μm to 400 μm: In the natural state, the total thickness of the first to third layers is 70.
0 μm to 1250 μm. 8. The pleated cartridge filter according to claim 6 or 7, characterized in that the filter body has the following constitution in addition to the constitutions (1) to (5): The first layer non-woven fabric has a fiber diameter of 20 μm. ~ 80 μm
Of the synthetic resin fiber of: The basis weight of the non-woven fabric of the first layer is 50 to 150 g / m.
² : The opening of the nonwoven fabric of the first layer is 60 to 250 μm. 9. A condensate demineralizer in a condensate system of a power plant, comprising the pleated cartridge filter according to claim 1 as a filter in front of the condensate demineralizer. Filtration device. 10. A condensate system of a power plant, which comprises a precoat filter as a filter in front of the condensate demineralizer,
10. A method for updating a filter in a condensate system of a power plant, wherein the pleated cartridge filter according to any one of claims 1 to 9 is mounted instead of the precoat filter.