JP2008093644A - Bag filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bag filter which can filter out all the unfiltered liquid and also dehydrate a cake after being filtered although the unfiltered liquid remains in a bag when a liquid to treated, containing fine or solid particles, is solid/liquid separated by a conventional bag filter. <P>SOLUTION: The bag filter, equipped with a housing 1, a basket 5 to be housed in the housing 1, and a bag 6 to be housed in the basket 5, is structured to house a liquid-removing pipe 13 having a circular flange 14 on the upper-end outer peripheral side of a cylindrical part 15 in the bag 6 and to be able to seal the flange-part lower side of the liquid-removing pipe 13 and the peripheral part of a bag opening so that the unfiltered liquid in the bag 6 is compressed with compressed air to be entirely filtered. Also, after finishing of filtering, the cake is dehydrated by aeration with the compressed air to form a dehydrated cake. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a bag filter of a pressure filter for liquid used for solid-liquid separation.

The conventional bag filter is easy to use because it has a compact structure and can easily change the bag of the filter medium. Further, since it can reduce waste, it is more economical than the cartridge filter and has been used in a wide range of fields in recent years. When filtering using this bag filter, when the bag is clogged and the bag is taken out, unfiltered liquid remains in the bag.
In particular, when using a treatment liquid with small catch particles and a large filtration resistance or a bag with a large filtration area, there is a problem that the unfiltrated liquid cannot be eliminated, which is one of the drawbacks of the bag filter.

The problem to be solved is that all the unfiltered liquid remaining in the bag can be filtered, and the remaining cake is dehydrated to reduce the amount of cake remaining in the bag as much as possible. The purpose is to reduce the amount of things.

Means to solve the problem

The present invention includes a housing having a main body and an upper lid that seals the opening of the upper end of the main body so as to be openable and closable, a basket accommodated in the housing formed with a plurality of holes, and accommodated in the basket. A bag filter having an annular flange on the outer peripheral surface of the cylindrical upper end, and the cylindrical lower portion accommodates a drainage pipe formed in an opening in the bag, and the upper end of the drainage pipe The brim portion can be installed on the peripheral edge of the opening of the bag.
The collar portion is pressed by a top cover portion of the housing via a spring member or a seal member, so that the bottom surface of the collar portion of the drainage pipe and the peripheral edge of the bag opening can be sealed.

The invention's effect

As an effect of the present invention, by using the drainage pipe according to the present invention, the compressed air supplied from the upper part of the main body enters the drainage pipe, the compressed air does not leak, and the unfiltered liquid in the bag Can be filtered to promote filtration, and a uniform cake can be formed on the entire inner surface of the bag to filter the entire amount of the unfiltered liquid. In addition, by continuing to supply compressed air after filtration, the residual liquid in the cake is aerated and dehydrated, resulting in a dry cake with a low water content, reducing the amount of cake discarded and causing contamination by dripping when the bag is removed. The weight is reduced and the bag can be easily replaced.

The drainage pipe preferably has a circular cross-sectional shape, but may have a polygonal shape, a star shape, or the like.
In order to reduce the amount of liquid in the cylinder part, the cylinder part may have a double pipe structure, or a dummy material may be fixed inside the cylinder part to increase the volume of the cylinder part. The material of the tube portion is usually made of metal, but when the amount of cake is large, it is also possible to use rubber or resin that can deform the tube. It is appropriate that the length of the cylindrical portion is usually about 20 mm to 200 mm shorter than the overall length of the bag.

A first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a cross-sectional view of a conventional bag filter at the time of liquid removal.
The housing 1 is a sealed container having a cylindrical tank main body 2 having an open upper end and an openable / closable upper lid 3, and a basket 5 is provided on the inner diameter side of a locking ring 4 provided inside the main body 2. The basket 5 is made of a perforated plate, and is a cylindrical container having an opening at the top. A bag 6 as a bag-like filter medium is accommodated therein, and the opening peripheral edge is pressed by a fixing metal 7 and a spring 8 to be sealed. ing.
A liquid inlet valve 9, a filtrate outlet valve 10 and an air inlet valve 11 are connected to the main body 2, and a deaeration valve 12 is connected to the upper lid 3.

Next, in the filtration step during operation, the processing liquid pressurized and supplied from the liquid inlet valve 9 into the main body is filtered from the inside to the outside of the bag 6, the filtrate is sent out from the filtrate valve 10, and the solid particles are sent to the bag. Remain in 6. When the bag 6 is replaced after the filtration is completed, a liquid removal step of filtering the unfiltrated liquid inside the main body 2 is performed. In the liquid removal step, the liquid inlet valve 9 is closed and the air inlet valve 11 is opened and pressurized with compressed air to filter the unfiltered liquid in the main body 2. If it falls, compressed air leaks from the part which became the air layer part of the bag 6, is exhausted from the filtrate outlet valve 10, and the pressure in the main body 2 approaches atmospheric pressure. The unfiltered liquid in the bag 6 is filtered with a slight pressure difference, and it takes a long time to filter the whole amount, or in the case of a treatment liquid having a large cake resistance, filtration is almost impossible. Unfiltrated liquid A remains in it.

FIG. 2 shows a cross-sectional view of the bag filter of the present invention at the time of liquid removal process.
In the bag filter of the present invention, the fixing bracket 7 is simply replaced with the drainage pipe 13 in the configuration of the conventional bag filter shown in FIG. In the dewatering step according to the present invention, the compressed air supplied from the air inlet valve 11 pressurizes the unfiltered liquid remaining in the main body 2 until the liquid level reaches the opening at the lower end of the cylinder of the dewatering pipe 13. Filtration can continue. When the liquid level passes the lowermost end of the drainage pipe 13, the compressed air is vented from the entire filtration area of the bag 6, and the retained liquid in the cake is aerated and dehydrated, so that the dehydrated cake B having a low moisture content is obtained. .
In the first embodiment, a case where one bag 6 is used for the main body 2 is shown, but a plurality of bags 6 to be attached to the main body 2 may be used.
Moreover, in Example 1, although the side liquid injection method which provided the liquid inlet in the upper part of the main body is shown, it can also be set as the top liquid injection method which provided the liquid inlet in the upper cover part.

3 and 4 show detailed views of the drainage pipe.
The drainage pipe 13 is provided with an annular collar 14 at the upper end of a cylindrical portion 15 that is 20 mm to 200 mm shorter than the overall length of the bag 6 and can be installed on the opening peripheral edge of the bag.
A guide 16 may be provided on the outer peripheral surface of the cylindrical portion 15 in order to reduce the burden on the bag 6 due to shock, vibration, and pulsation during operation, and to correctly accommodate the bag 6 in the basket 5.

As an application example of the present invention, it is most suitable for a slurry processing liquid that requires fine solid-liquid separation including fine solid particles.
In addition, since the amount of cake discarded can be significantly reduced by aeration and dehydration for a treatment liquid having a high slurry concentration and a large amount of cake, it is effective to use the bag filter of the present invention.

  Cross-sectional view of a conventional bag filter   Sectional drawing of the bag filter of Example 1   Sectional drawing of the drainage pipe of Example 1   Bottom view of the drainage pipe of Example 1

Explanation of symbols

1: Housing 2: Body 3: Upper lid 4: Locking ring 5: Basket 6: Bag 7: Fixing bracket 8: Spring 9: Liquid inlet valve 10: Filtrate outlet valve 11: Air inlet valve 12: Deaeration valve 13: Degassing Liquid pipe 14: Brim 15: Tube portion 16: Guide A: Unfiltrated liquid B: Dehydrated cake

Claims (1)

A housing having a main body and an upper lid for sealing the opening of the upper end of the main body so as to be openable and closable, a basket accommodated in the housing in which a plurality of holes are formed, and a bag accommodated in the basket In the bag filter provided, the cylindrical upper end has an annular collar on the outer peripheral surface of the cylindrical upper part, the cylindrical lower part accommodates a drainage pipe formed in the opening in the bag, and the upper end flange part of the drainage pipe It can be installed on the opening periphery of the bag.
The bag filter has a structure in which the flange portion is pressed by an upper lid portion of the housing via a spring member or a seal member so that the lower surface of the flange portion of the drainage pipe and the peripheral edge of the bag opening can be sealed.

Images