JPH08126806A - Filter element for tubular filter - Google Patents

Abstract

PURPOSE: To stably deposit cake on a filter element and to prevent the cake from being removed carelessly by stretching a tubular filter medium from the inside to form the filter element and forming rugged parts on the outer periphery of the filter element in the axial direction. CONSTITUTION: This filter element 81 used in a tubular filter is constituted mainly by a spiral tube 10 that a straight tube having a lot of small holes 15 twisted in a spiral form. The lower end of the tube 10 is liquid-tightly sealed by a bottom plate, and the upper end thereof is closed by a cover plate 11 through whose central part a hollow pipe 13 is passed. In the upper part of the hollow pipe 13, a screw part 14 is formed and is screwed with a female screw of a collecting pipe. A tubular filter medium 16 is fitted to the filter element 81. At this time, the lower part of the filter element 16 is liquid-tightly fitted to the bottom plate by a rubber ring and a locking ring and the upper end thereof is similarly fitted to the cover plate 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter element for expanding a tubular filter medium used in a tubular filter from the inside.

[0002]

2. Description of the Related Art FIG. 4 shows a basic structure of a tubular filter which has been frequently used. In the figure, 1 is a container body,
A stock solution is supplied from the stock solution supply port 2 into the container body 1. A filter element 8 is suspended in the container body 1, and an upper end of the filter element 8 communicates with a collecting pipe 9. One end of the collecting pipe 9 is guided to the outside of the container body 1 and serves as a filtered liquid outlet 3. A tubular filter medium (not shown in FIG. 4) is covered around the tubular filter element 8 to carry out a filtering operation. In the figure, 6 is an openable / closable lid, 7 is a flange for closing the lid 6, and 5 is an exhaust port. A cake outlet 4 is provided at the bottom of the container body 1.

[0003]

[0004] With the tubular filter medium covering the filter element 8, the stock solution is supplied from the stock solution supply port 2, and the container body 1
When the internal pressure rises, the stock solution is sent into the filter element 8 while being filtered by the tubular filter medium, and the filtered solution is collected by the collecting pipe 9 and sent out from the filtered solution outlet 3. In this way, while the filtered liquid is obtained from the filtered liquid outlet 3, the cake is deposited around the tubular filter medium. During this filtering action, the tubular filter medium is stretched by the filter element 8 from the inside.

After the cake is deposited around the tubular filter medium, the stock solution in the container body 1 is discharged and compressed air is blown from the filtered solution outlet 3 to reverse the tubular filter medium pressed against the filter element 8. A technique has been developed in which the cake accumulated around the tubular filter medium is peeled off from the tubular filter medium by inflating it into a tubular filter medium.
013070, JP-A-57-204208 or JP-A-3-94804.

In these techniques, unevenness is provided in the circumferential direction in the cross section of the filter element 8 and the filter element 8
During the filtration process that is pressed against and when the tubular filter medium is inflated by sending compressed air from the filtered liquid outlet 3.
The shape of the tubular filter medium is changed so that the cake can be reliably peeled from the tubular filter medium. For example, in Japanese Unexamined Patent Publication No. 54-13070, the cross-sectional shape of the filter element is star-shaped, and in Japanese Unexamined Patent Publication No. 57-204208, a plurality of pipes are arranged in parallel around one central pipe. Japanese Patent Laid-Open No. 3-94804 discloses a technique in which the cross-sectional shape is substantially a gear shape.

[0007]

As described above, the conventional filter element is provided with unevenness in the circumferential direction in its cross-sectional shape so that the cake is surely peeled off from the tubular filter medium. However, in all the prior arts, the filter element extends uniformly in the axial direction. For this reason, the conventional filter element is apt to have a problem that the cake sometimes inadvertently comes off from the filter medium.

After the cake is deposited around the filter medium, the stock solution is discharged from the container body 1 and compressed air is blown from the filtered solution outlet 3 due to pressure fluctuations in the container body 1. The cake may peel off locally from the filter medium, or the cake may shift from the filter medium due to its own weight. When such a phenomenon occurs, the air blown from the filtered liquid outlet escapes from the peeled portion of the cake, making it impossible to sufficiently inflate the filter medium. For this reason, the cake may not be partly peeled off.

After the cake is deposited around the filter medium, the compressed air may be blown into the container body 1 through the exhaust port 5. In this case, the stock solution in the container body 1 is first pressurized and filtered, and then filtered and then discharged from the filtered solution outlet 3. If the compressed air is still blown from the exhaust port 5, the compressed air will pass through the cake and be blown out from the filtered liquid outlet 3 this time. During this time, the cake is drained, and when compressed air is blown from the filtered liquid outlet 3 to separate the cake from the filter medium, a dry cake is discharged from the cake discharge port 4.

In this type of operation, if the cake is locally peeled from the filter medium while the compressed air is being blown from the exhaust port 5, the air is introduced into the filter element from the portion where the cake is peeled off. , And is discharged from the filtered liquid outlet 3. For this reason, sufficient pressure does not act on the stock solution, and the stock solution remains in the container body 1, or the cake is discharged with insufficient deliquoring of the cake.

The present invention is intended to solve the above-mentioned problems. When compressed air is blown from the filtered liquid outlet 3, the cake is not only peeled off from the filter material but also compressed air is filtered. While not being blown from the outlet 3, the cake continues to be stably deposited on the filter medium to prevent the cake from coming off accidentally.

[0012]

In view of the above, according to the present invention, in a filter element used in a tubular filter in which a tubular filter medium is stretched from the inside, irregularities along the axial direction are formed on the outer periphery of the filter element. In this case, it is preferable that the outer shape of the filter element is formed in a spiral shape to form the unevenness in the axial direction. Further, it is preferable that the filtration element has a spiral outer shape and unevenness in the axial direction by twisting a straight tube in which a large number of small holes are dispersed in a spiral shape.

[0013]

When the outer periphery of the filter element is formed with an unevenness along the axial direction, the filter medium is pressed against the filter element during the filtration process, and the filter medium is formed with the unevenness in the axial direction on the filter element. The cake accumulates. Therefore, the cake is stably deposited on the filter element and is prevented from being peeled off inadvertently. When compressed air is blown out from the filter element side in this state, the filter medium swells outward in the axial recess, and the shape of the filter medium changes significantly. For this reason, the cake deposited on the filter medium is surely peeled off from the filter medium. In this way, while the cake does not peel off carelessly,
If you try to peel it off, you will get the effect of sure peeling.

In particular, when the outer shape of the filter element is a spiral shape, when the filter medium is inflated with air, a twisting motion occurs in the filter medium, and the cake is reliably separated from the filter medium. If the filter element is a straight tube with many small holes twisted in a spiral shape, in addition to the above effect, the filtered liquid enters the filter element through many small holes and the The pressure loss during processing is reduced,
The filtration efficiency is improved.

[0015]

1 shows the outer shape of a first embodiment of the filter element 8 used in the tubular filter shown in FIG. 5 shows a longitudinal sectional view of a state in which the tubular filter medium 16 is covered around the filter element, and FIGS. 6 and 7 show transverse sectional views. 6 shows a cross-sectional view during the filtration process, and FIG. 7 shows a cross-sectional view when the filter medium is inflated to remove the cake.

The filter element 81 of the first embodiment is shown in FIG.
As shown in FIG. 3, the spiral tube 10 is mainly configured by spirally twisting a straight tube having a large number of small holes 15. The bottom end of the spiral tube 10 is liquid-tightly sealed by a bottom plate 12 (see FIG. 5). The upper end of the spiral tube 10 is closed by a lid plate 11, and a hollow tube 13 penetrates the central portion of the lid plate 11. A threaded portion 14 is formed on the upper portion of the hollow tube 13 and is screwed to a female thread provided in the collecting tube 9 of FIG. The cross section of the spiral tube 10 is a substantially equilateral triangle as shown in FIGS. 6 and 7, and the hollow tube 13 is inscribed therein.

As shown in FIG. 5 and subsequent figures, a tubular filter medium 16 is attached to this filter element 81. The lower end of the tubular filter medium 16 has a rubber ring 17 and a stop ring 1.
It is liquid-tightly attached to the bottom plate 12 by 8, and the upper end is liquid-tightly attached to the lid plate 11 by the rubber ring 17 and the retaining ring 18. The cross section of the tubular filter medium has an area that extends in a circle around the equilateral triangle cross section of the filter element 81, as shown in FIG. The tubular filter is operated with the tubular filter medium 16 attached to the filter element 81 and attached to the collecting pipe 9.

In FIG. 4, the lid 6 is closed with a flange 7,
With the exhaust port 5 open, the stock solution is fed into the container body 1 from the stock solution supply port 2 by a pump (not shown) to fill the container body 1 with the stock solution. Next, the exhaust port 5 is closed to feed more undiluted solution. Then, the pressure in the container 1 rises, and the filter medium 16
Are pressed against the filter element 81 (FIG. 6). In this state, the stock solution is sent into the filter element 81 through the filter medium 16 and the many small holes 15, and the liquid filtered by the filter medium 16 passes through the spiral groove between the filter element 81 and the hollow tube 13. After moving downward, the hollow tube 14 is moved up and then sent out to the filtered liquid outlet 3 through the collecting pipe 9. In this way, the stock solution is filtered and then sent to the filtered solution outlet 3. A cake is accumulated on the outer periphery of the filter medium 16 along with this filtering process. This cake fits into the shape of the filter element 81 due to the spiral groove, and since it is strongly deposited due to the unevenness in the axial direction, it does not come off accidentally. Also, the cake is effectively prevented from shifting due to its own weight.

The thicker the cake, the lower the filtration efficiency. Therefore, after stopping the supply of the stock solution, the compressed air is supplied from the exhaust port 5. Then, the stock solution in the container 1 is pressurized, filtered by the filter medium 16, and then discharged from the filtered solution outlet 3. If the compressed air is still sent from the exhaust port 5, the undiluted solution is discharged from the container 1, and the cake flows from the container 1 side into the filter element 81 through the cake to dry or deliquefy the cake. To be

When the cake deliquoring process is completed, the cake discharge port 4 is opened, and then compressed air is blown from the filtered liquid outlet 3. Then, the filter medium 16 swells as shown in FIG. 7, and at this time, the cake is peeled off from the filter medium 16 and drops into the cake discharge port 4. In this case, during the filtering process and the deliquoring process of the cake, the cake is deposited on the filter medium due to the spiral shape, and for example, even if the pressure in the container fluctuates or air is passed for deliquoring the cake. Is not accidentally peeled off from the filter medium. Therefore, the operation of discharging the stock solution from the container 1 is favorably performed, and the dewatering process from the cake is also favorably performed. However, when air flows backward from the filtered liquid outlet 3, the filter medium 16 is twisted back and swells to the state shown in FIG. 7. At this time, a movement that does not fit between the filter medium 16 and the cake is caused, and the cake surely falls off from the filter medium.

FIG. 2 shows a filter element 82 according to the second embodiment. In this case, a thick coil spring-shaped coil 83 constitutes the filter element. First
The hollow tube 13 used in the embodiment may be omitted.
Also in this case, the outer shape of the filter element is a spiral shape, so that the cake can be easily prevented from peeling due to the unevenness in the axial direction. Even in this case, when the filter medium is inflated, the cake surely comes off.

FIG. 3 shows a third embodiment, in which the flange 85 is provided with axial irregularities on the outer shape of the filter element 84. In this case, the small hole 86 is formed in a slit shape. Also according to this embodiment, the cake is deposited on the unevenness in the axial direction, and it is effectively prevented that the cake is peeled off accidentally.

[0023]

According to the present invention, the cake is deposited on the irregularities in the axial direction, and the cake is effectively prevented from being accidentally peeled off from the filter medium. On the other hand, when the treatment for peeling the cake is performed, the filter medium is largely deformed in the concave portion, and the cake is surely peeled. In particular, when the outer shape of the filter element is a spline shape, when the filter medium is inflated, the filter medium is twisted and swells, and since this movement does not match with the cake, the cake is reliably peeled from the filter medium. Further, if a straight tube is twisted into a spline shape to form a filter element, the holding and peeling of the cake will be more stable, and the operating efficiency of the filter will be greatly improved.

[Brief description of drawings]

FIG. 1 is an external view of a filtration element according to a first embodiment.

FIG. 2 is an external view of a filter element according to a second embodiment.

FIG. 3 is an external view of a filter element according to a third embodiment.

FIG. 4 is a diagram showing the overall configuration of a filter.

FIG. 5 is a vertical sectional view when a filter medium is attached to the filter element.

FIG. 6 is a cross-sectional view during the filtration process and the liquid removal process.

FIG. 7 is a cross-sectional view when peeling the cake.

[Explanation of symbols]

8,81,82,84 Filtration element with irregularities in the axial direction 15,86 Porous 81,82 Spiral filtration element 85 Flange 86 Slit-shaped hole

Claims (3)

[Claims] 1. A filter element for a tubular filter in which a tubular filter medium is stretched from the inside, wherein the filter element is provided with irregularities formed along the axial direction on the outer periphery thereof. 2. The filter element according to claim 1, wherein the outer shape is a spiral shape, so that unevenness in the axial direction is formed. 3. The filter element according to claim 1, wherein the porous straight tube is twisted in a spiral shape to form an unevenness in the axial direction.