JPH0417683B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter cloth for solid-liquid separation, and more specifically to a filter cloth for filter cloth traveling type filters, dehydrators, etc., which carry out filtration and dehydration by placing a solid liquid on a rotating endless filter cloth. This invention relates to a filter cloth used in a solid-liquid separator.

In recent years, a filter cloth has been developed in which a raised filter layer is formed on the surface of a textile base material by raising the base material. Along with this, such filter cloth is endlessly processed,
A so-called filter cloth traveling type filter, which supplies a solid liquid to the surface of the filter cloth and separates the solid component and liquid component in the solid liquid while circulating the endless filter cloth in one direction on a fixed orbit. Dehydrators (hereinafter collectively referred to as solid-liquid separators) have been developed. However, the endless filter cloths used in such solid-liquid separators have drawbacks as explained below.

In other words, in the above-mentioned filter cloth, since the fabric is directly raised to form a raised filter layer, the
Compared to so-called raw textiles, it has very low dimensional stability, and is prone to stretching, bending, and wrinkles due to the weight of solids and liquids and the tension during running.
This phenomenon is not so severe in the vicinity of both ends of the filter cloth in the width direction because there are driving perforated belts at both ends, but it is most noticeable in the central region where it is less likely to be restricted by such belts. and,
If stretching, bending, wrinkles, etc. occur, the condition of the base material's grains and filter layer will change, making stable solid-liquid separation impossible.

In order to solve this problem, conventional solid-liquid separators take measures such as lowering the spreading tension of the filter cloth and minimizing the number of parts that rub against the filter cloth. However, when the tension of the filter cloth is lowered, the running stability is further reduced. Furthermore, there is a limit to reducing the number of frictional sliding parts.

On the other hand, as another countermeasure, it is conceivable to make the thickness of the base material sufficiently thick. However, if this is done, another problem arises in that the passage coefficient of the liquid component decreases and the processing capacity decreases.

An object of the present invention is to solve the above-mentioned drawbacks of conventional filter cloths, to provide a filter cloth that can suppress the occurrence of elongation, bending, wrinkles, etc., and can perform stable solid-liquid separation.

In order to achieve the above object, the present invention provides at least the center in the width direction of a filter cloth formed by raising the nap on the surface of an endlessly processed woven or knitted fabric base material to form a napped filter layer. There is provided a filter cloth for solid-liquid separation, characterized in that a reinforcing band is provided integrally with the filter cloth and over the entire circumferential length of the filter cloth.

To explain one embodiment of the filter cloth of the present invention, in the drawing, a filter cloth 1 is sewn together along dotted lines and processed into an endless shape. Perforated belts 2 and 3 are sewn to both ends of the filter cloth 1 to stretch the filter cloth 1 and run it without meandering. The belts 2 and 3 are made of rubber or a composite material of synthetic fiber fabric and rubber. Further, a reinforcing band 4 is provided at the center of the filter cloth 1 in the width direction, integrally with the filter cloth 1, and extending over the entire length in the circumferential direction.

Preferably, the filter cloth is as described in, for example, Japanese Patent Application No. 57-93591 and Japanese Patent Application No. 57-226384. In other words, at least the single yarn diameter of the weft yarns arranged in the width direction of the filter cloth is
A knitted fabric or woven fabric base material using synthetic fiber multifilament with a thickness of 0.1 to 10 μm is used, and the weft yarns of the base material are raised in the circumferential direction to coat the surface of the filter cloth with a thickness of 0.1 μm.
It is preferable to create a nap of ultrafine fibers of ~10 μm and form a filter layer with the nap.
In such a filter cloth, since the nap is carried out in the circumferential direction, the nap lies in that direction, that is, it has directionality. Therefore, when in use, the filter cloth is stretched so that the nap is directed in the opposite direction to the running direction of the filter cloth.

The reinforcing band is integrated with the filter fabric, for example by stitching or by gluing. Among them, so-called heat treatment involves sandwiching a sheet or powder of a low-melting point polymer, such as polyester resin, polyamide resin, or polyvinyl chloride resin, between the filter cloth and the reinforcing band and heating the sheet or powder to melt the sheet or powder. Preferably, they are integrated by fusion. Note that the above belt with holes may also be joined by this method.

The reinforcing band may be constructed by using the base material as it is before raising, or it may be constructed from a material different from the base material, such as a woven fabric or a synthetic resin film. Further, it may be a multi-filament or monofilament of synthetic fiber, or a linear body or band-shaped body of metal. In short, the reinforcing band only needs to have lower elongation and tensile strength than the filter cloth.

In the above embodiment, reinforcement is provided only in the widthwise center of the filter cloth, where elongation, bending, wrinkles, etc. are most likely to occur, but reinforcement may also be provided near the belt on the weight side. , two or more reinforcing bands may be provided, such as two reinforcing bands provided only in the central portion. Note that the reinforcing band may be provided on the front side or the back side of the filter cloth.

Further, the width of the reinforcing band may be determined depending on the number of installed reinforcing bands, the type of filter cloth, the running speed, etc., but it is preferable that the width is as narrow as possible so as not to reduce the effective area of the filter cloth. Usually 0.5~5cm
A certain amount is enough.

The filter cloth of this invention can be used in a so-called filter cloth traveling type transfer type dehydrator that uses a transfer drum, a so-called twin cross type dehydrator that squeezes a solid liquid between two filter cloths, or a squeezing mechanism. It can be used in so-called filter cloth traveling type filters.

Additionally, the filter cloth of this invention can be used to separate various solids and liquids. For example, it can be used to separate solid and liquid components contained in lake water or river water. In addition, sludge, scum, etc. generated by sewage treatment, such as so-called suspended sludge, such as surplus sludge produced by activated sludge treatment equipment, and so-called fixed sludge, discharged from biofilm treatment equipment, It can be used for filtering, concentrating, and dehydrating flocs, wash water, sludge, etc. Specifically, for example, sludge generated from water and sewage treatment, excess sludge generated from septic tanks, sludge generated from human waste treatment plants, scum generated from pressurized flotation operations, flocs generated from industrial wastewater treatment, It can be used to separate solid components and liquid components contained in backwash water from various filters such as sand filters. Furthermore, it can be used for solid-liquid separation in various manufacturing industries, such as paper pulp manufacturing, food manufacturing, sake brewing, and miso brewing, and for the recovery of valuables in chemical processes. As explained above, since the filter cloth of the present invention is provided with a reinforcing band at least at the center in the width direction, integrally with the filter cloth and extending over the entire length in the circumferential direction, the weight of the solid-liquid It is possible to prevent elongation, bending, and wrinkles due to running resistance. Therefore, it is possible to prevent the running of the filter cloth from becoming unstable or from being deformed and changing the condition of the base material and the filter layer, and it is possible to obtain stable solid-liquid separation and processing capacity. The above-mentioned effect of the reinforcing band is particularly remarkable in relatively thin filter cloths having a basis weight of 300 g/m ² or less. The effect of improving solid-liquid separation performance and processing capacity is sufficiently greater than the reduction in these effects due to the reduction in the effective filtration area of the filter cloth due to the installation of the reinforcing band.

[Brief explanation of drawings]

The drawing is a schematic perspective view showing one embodiment of the filter cloth of the present invention. 1: Filter cloth, 2, 3: Belt with holes, 4: Reinforcement band.

Claims (1)

[Claims] 1 At least in the center in the width direction of a filter cloth formed by raising the nap on the surface of an endlessly processed woven or knitted fabric base material to form a napped filter layer, integrally with the filter cloth and its A filter cloth for solid-liquid separation characterized in that a reinforcing band is provided along the entire length in the circumferential direction.