JP4204338B2 - Filter disc and leaf filter - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a filter disk, and a leaf filter mainly used for filtering a highly viscous fluid, which is configured so that the flow of the liquid to be filtered becomes a cocurrent flow as a unit. In particular, it is suitable for a filter for the purpose of filtering and removing foreign substances and gelled substances contained in a liquid polymer in the production process of synthetic fibers and synthetic films.
[0002]
[Prior art]
For filtration of high viscosity fluids such as synthetic fiber melt spinning and plastic film forming process, the polymer material is piled on both sides using a disk-shaped spacer and fixed to form a filter disk. As a filter unit, a leaf filter for highly viscous fluid in which a plurality of sheets are stacked in a abacus bead shape in the central axis direction and stored in a pressure vessel is widely used. The spacer serves to support the filter and to form a flow path for the filtrate, and the filtrate to be filtrated is pressurized and fed into the pressure vessel, and passes through each filter disk from the filter medium side to the spacer side in parallel flow. Then, the gelled material and the foreign substances are filtered and removed, and flow as a filtrate toward the center through the spacer, and are collected and led out of the container.
[0003]
Conventionally, the above filter disk is used as a filter unit by cutting a metal mesh into a disk shape as a spacer, stacking the filter medium on both sides via a porous plate retainer, sealing the filter medium and separating the outer surface of the filter medium and the spacer. It was done. Recently, coil-shaped wire rods that are bent into a ring shape and arranged concentrically, or spirally wound into a disk shape have been proposed.
[Patent Literature]
Japanese Utility Model Sho 64-016313
[0004]
[Problems to be solved by the invention]
However, the conventional filter disk using a wire mesh as a spacer has the advantage of a simple structure and low manufacturing cost, but it has stable anisotropy because it has a large anisotropy in the flow in the spacer and easily forms a gel. There was a disadvantage that could not be used for a long time. In addition, the newly proposed filter disk, which is formed by bending a coiled wire rod into a disk, has a low anisotropy and has a low resistance to filtration because it has a small anisotropy and flows uniformly in all directions. Although there is a merit that it is difficult to generate chemicals, the coiled wire is misaligned and meshed, the pitch shifts and the pitch becomes coarse and dense, and it deforms due to filtration pressure, so the flow becomes non-uniform over time Thus, there are still problems in stable use over a long period of time. If high-grade spring steel is used for the coiled wire rod and the wire rod is fixed to the spacer by spot welding or the like, the above-mentioned problems can be solved to some extent, but the processing cost is high and a polymer retention portion tends to be generated in the welded portion. There is.
[0005]
Accordingly, the present invention provides an inexpensive filter disk that can be used under stable conditions for a long period of time and has little anisotropy in flow with respect to a highly viscous filtrate, is less likely to be deformed by filtration pressure, and a leaf filter mainly for a highly viscous fluid As a result of research on the subject.
[0006]
[Means for Solving the Problems]
The present invention will be specifically described with reference to the drawings. As a means for solving the above-mentioned problems, the present invention is a leaf filter filter disk 3 in which a filter medium 1 is stacked on both sides of a disk-shaped spacer 2, and the spacer 3 is made of two plain meshes or twill weaves 4, 4. Provided is a filter disk characterized by being formed by superimposing a bias on a bias within a range of 22.5 ± 7.5 degrees from each other.
[0007]
In the present invention, a plurality of the filter disks 3 are stacked, the center pole 12 provided with the filtrate flow path 11 is passed through the center of the filter disk, and the filtrate flow path is connected to the spacer side of the filter disk, A leaf filter is provided in which a liquid to be filtered is supplied from an outer surface side 13 of a filter disk, and the filtrate is led out from a flow path provided in a center pole.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be specifically described with reference to the drawings and embodiments. All the drawings are illustrations of the present invention. FIG. 1 is a schematic plan view of a spacer in which two wire meshes are formed to form the filter disk of the present invention, and FIG. 2 is a spacer in which two wire meshes are stacked on a bias. Is a graph in which the directivity is measured with the bias angle as a parameter, the pressure loss as a vertical axis, and the flow direction as a horizontal axis. 3 is an axial sectional view of the filter disk, and FIG. 4 is an axial sectional view of the main part of the leaf disk filter.
[0009]
Now, it is considered that most of the problems related to the filter disk are caused by the quality of the spacer. In filtration of a highly viscous fluid such as a molten polymer, the entire filter medium is effectively used evenly when the liquid to be filtered passes through the filtration surface uniformly, and the filter disk can be used stably over a long period of time. Usually, since the entire filter medium is configured uniformly, the filter medium itself does not cause anisotropy or unevenness in the flow of the liquid to be filtered. A major cause of non-uniformity in filtration is the non-uniform flow of filtrate in the spacer. When the filtrate produces a non-uniform flow on the filtration surface, the effective filtration area is substantially reduced, and a gelled product is generated in the staying portion, greatly affecting the filter life.
[0010]
Therefore, in the present invention, a means for solving the problem while examining the merit of the spacer using the wire mesh was studied. As a result, it was found that the problem of flow anisotropy, which is a drawback, can be solved very effectively by using a very simple wire mesh. In general, a single wire mesh is anisotropic in the ease of flow in the wire mesh surface. However, if a plurality of wire meshes are used in an overlapping manner, the anisotropy of each other can be eliminated and a characteristic close to isotropic can be obtained. In a metal mesh, anisotropy is significantly reduced if the two sheets are superimposed on a 45 degree bias. However, the two types of wire mesh of the same type are overlapped with each other in a range of 22.5 ± 7.5 degrees, particularly 22.5 ± 2.5 degrees, and are different from each other. It was found that the directionality was surprisingly dramatically reduced. The experimental results are shown in FIG.
[0011]
In this experiment, two plain woven wire nets with a diameter of 0.8 mm × 8 mesh and a thickness of 1.25 mm were stacked and processed into a spacer with a thickness of about 2.5 mm. Three types of spacers were used: two metal meshes with parallel meshes (parallel), one overlaid on a 45 ° bias, and one overlaid with a 22.5 ° bias.
[0012]
As shown in FIG. 5, these spacers 2 are covered with clay by leaving a predetermined range (measurement flow path: defined by an angle) 21 centered on the pressure loss measurement direction, while leaving the other portions 22 in an X shape. The sample was held between the two test specimen holding members 23 shown in FIG. 2 and fixed, and the pressure loss was measured by suction from a suction port 24 provided at the center of one of the disks. In addition, although the fluid used in this experiment example is air, in order to reproduce the filtration environment of a highly viscous fluid, it implemented in the laminar flow area. FIG. 2 shows the pressure loss and the distribution measurement result when the flow rate is constant, with the channel direction indicated by the angle from the reference position as the horizontal axis and the pressure loss as the vertical axis.
[0013]
As can be seen from FIG. 2, the anisotropy of the parallel stack is greatly reduced by overlaying the 45 degree bias, but it is also surprising that the anisotropy is almost eliminated by overlaying the 22.5 degree bias. The result is clear. Specifically, it is possible to superimpose two wire meshes on a bias (diagonal) within a range of 22.5 ± 7.5 degrees, and particularly on a bias (diagonal) within a range of 22.5 ± 2.5 degrees. desirable.
[0014]
A plain weave or twill weave is suitable for the wire mesh structure to be overlapped.
[0015]
Now, in general, the filter disk 3 is covered with a retainer 14 that holds the filter medium 1 on both sides of the spacer 2, and further overlaps the required filter medium 1 so that the retainer 14 and the filter medium 1 are in close contact with each other so that fluid does not leak at the outer peripheral edge. Let them fix and make. A porous plate or the like can be used as the retainer 14, and a metal nonwoven fabric or the like can be appropriately selected depending on the object to be filtered. By supplying the liquid to be filtered from the outer surface side 13 of the filter disk, the liquid to be filtered passes through the filter medium 1, is filtered, and flows into the spacer 2 side. Then, an opening portion having the same inner diameter as the center pole is provided in the spacer so that the filtrate flows in the center direction in the spacer 2 and flows out from the center portion, and a fluid passage is provided in the center portion. The hub 15 is attached.
[0016]
The filter disk 3 according to the present invention manufactured in this way is stacked in a necessary number, is cylindrical or cylindrical, and connects the flow path 11 of the filtrate provided in the axial direction and the flow path 11 to the spacer side. A center pole 12 having a communication flow path 16 is passed through the center of the filter disk 3, the spacer 2 side is connected to the flow path 11, and the leaf filter body is assembled.
[0017]
Although FIG. 4 shows an example using a center pole that is cylindrical and has a flow path in the cylinder, a square pole or a square cylinder center pole can also be used. Since the hub is usually formed in a cylindrical shape, when a square cylindrical center pole is used, a space is created between the inner surface of the hub and the outer surface of the center pole. The road and the flow path on the center pole side can be easily communicated.
[0018]
Further, depending on the use conditions, the liquid to be filtered can be supplied from the flow path provided in the center pole to the outer surface side of the filter disk, and the filtrate can be led out from the spacer side.
[0019]
And in order to give a required filtration pressure, a filter main body is generally accommodated in a pressure-resistant casing (not shown), and a filtrate supply port and a filtrate discharge port are attached and completed. As described above, the case where the liquid to be filtered is supplied under pressure has been described. However, depending on the filtration conditions, the filtrate may be reduced in pressure and filtered.
[0020]
【The invention's effect】
As described above, by using the filter disk and the leaf filter according to the present invention, the flow is kept uniform even when used for a long period of time, the life of the filter medium is prolonged, the gelation is prevented, and the cost is reduced. It can contribute to production rationalization. The present invention is particularly effectively used for polymer filtration in the spinning process of synthetic fibers and the film forming process of films.
[Brief description of the drawings]
FIG. 1 is a schematic plan view of a spacer in which two metal meshes are used in a filter disk of the present invention. FIG. 2 is a spacer in which two metal meshes are superimposed on a bias. A graph of the directivity measured on the horizontal axis of the axis and flow direction.
[Fig. 3] Axial cross-sectional view of the filter disc [Fig. 4] Axial cross-sectional view of the main portion of the leaf disc filter [Fig. 5] Shows the flow direction in the spacer measured in the experimental example [Fig. Schematic [Explanation of symbols]
1: Filter medium 2: Spacer 3: Filter disk 4, 4 ': Plain weave wire mesh for spacer 11: Flow path of filtrate 12: Center pole 13: Filter disk outer surface side 14: Retainer 15: Hub 16: Communication flow path 21: Measurement Flow path 22: Portion covered with clay 23: Specimen holding member 24: Suction port

Claims (2)

In the filter disk (3) for leaf filters in which the filter medium (1) is overlapped on both sides of the disk-shaped spacer (2), the spacers are connected to each other with two wire meshes (4, 4 ') of plain weave or twill weave. A filter disk characterized by being superimposed on a bias (oblique) within a range of 5 ± 7.5 degrees. A plurality of filter disks (3) according to claim 1 are stacked, and the flow path (11
) Is passed through the center of the filter disk, the flow path of the filtrate is connected to the spacer side of the filter disk, and the liquid to be filtered is supplied from the outer surface side (13) of the filter disk. A leaf filter characterized in that liquid is led out from a channel provided in the center pole.

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