JPH0451037Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Field of Industrial Application) The present invention relates to a synthetic resin monofilament filter cloth for belt press type dehydrators. (Prior Art) A belt press type dehydrator basically has a structure as shown in FIG. The sludge is flocculated by a polymer flocculant in the flocculation treatment tank, and is suspended together with separated free water. The sludge transferred from the flocculation treatment tank onto the filter cloth exists in the state of large, small, and fine flocs, and the spaces between them are composed of free water, but as the filter cloth runs, sedimentation and filtration progress, and the sludge A deposited layer of flocs, a so-called cake, is formed. The filtration properties decrease in proportion to the thickness, and when a certain resistance is reached, the progress of filtration stops.
This stage is the process of the gravity filtration section. The sludge is then squeezed between two filter cloths, the top and bottom, and further squeezed using mechanical force. This process corresponds to the pressure dehydration section and the shear compression dehydration section. The filter cloth used in this belt press type dehydrator generally uses monofilament with a diameter of 0.5 mm or more for both the warp and weft, but sometimes it uses multifilament, as well as plain weave and herringbone single-ply fabrics. is often used. (Problems to be Solved by the Invention) In the filter cloth using the monofilament of the prior art, the diameters of the warp and weft are thick and the density is coarse, so the pores or meshes formed are relatively large. Therefore, after the filtration resistance increases in the gravity filtration section and reaches a certain level of resistance, leakage of sludge often occurs due to compression and shear force in the pressurization and shearing section. In an attempt to avoid this, increasing the warp density and reducing the mesh will eliminate the leakage, but the water permeability will decrease and the dewatering function will deteriorate. Furthermore, even if a filter cloth using multi-filament is used, sludge will not leak, but the elongation of the filter cloth will increase, single thread breakage will occur due to wear, and the durability against mechanical tension and abrasion will be reduced. do not have. (Means for solving the problem) The present invention uses twisted threads made by twisting synthetic resin monofilaments of the same wire diameter with thin wire diameters as the warp threads, thereby eliminating voids in the cross section of the warp threads in the filter cloth. The idea is to form a large number of pores and use the capillary phenomenon to promote filtration through the pores, and to make each pore have the same area to achieve uniform filtration. Figures 1a and b are a perspective view of the surface of a filter cloth according to the present invention and an enlarged sectional view of its warp, respectively, and Figures 2a and b are a perspective view of the surface of a conventional filter cloth whose warp is monofilament and its warp. FIG. 3 is an enlarged cross-sectional view of warp threads. The present invention is a filter cloth woven using synthetic resin monofilament as the warp, and the warp 1 has a wire diameter.
A filter for a belt press type dehydrator, characterized in that a twisted yarn made by twisting 3 to 50 synthetic resin monofilaments of the same wire diameter 1F among synthetic resin monofilaments of 0.1 to 0.3 mm is used. It's cloth. If there are two or less twisted yarns, no voids can be formed between adjacent single fibers in the warp cross section, and if there are more than 50 twisted yarns, the number of voids formed by adjacent single fibers, that is, the number of voids in the warp cross section, is large. It takes too much time for filtration to utilize this void,
The effect of promoting filtration through the use of voids is lost. In order to obtain the effect of promoting filtration by utilizing voids, the number is preferably 3 to 20, more preferably 6 to 15. On the other hand, the monofilament warp in conventional technology generally uses a single synthetic resin monofilament 10 with a wire diameter of 0.5 mm or more, and multifilament yarn has a thin single fiber with a wire diameter of 0.5 mm or more. It is 0.1mm or less. (Function) As can be inferred from Figures 1a and b, the filter cloth according to the present invention, whose warp is made of twisted synthetic resin monofilament yarns having the same diameter and fine wire diameter, has pores between the yarns as a fabric. At the same time, because the warp yarns are twisted monofilament yarns with a small diameter, gaps, that is, voids in the cross section of the warp threads, are formed, and the area of each void is the same because the wire diameters of adjacent monofilaments are the same. . Therefore, the sludge supplied to the filter cloth on the belt press type dehydrator first passes through the gravity filtration section where free water is filtered through the pores formed in the filter cloth, and at the same time, large, medium, and fine flocs settle and pass through the filter cloth. The water is deposited on the surface of the warp, and dewatering is performed uniformly and easily by capillary action from the voids in the warp cross section formed in the warp in the pressurizing and pressing dewatering section of the next step. (Example) Examples 1 and 2 according to the present invention are shown below as Comparative Example 1,
When described in conjunction with 2, it is as shown in the table below.

[Table] In Example 1, 12 polyester monofilaments with a wire diameter of 0.2 mmφ are twisted together at a twist rate of 1.5 times/in to form the warp, and the same 0.8 mmφ polyester monofilament as in the past is used as the weft. It is a filter cloth with a 3/1 weave structure with a horizontal density of 52 fibers/in x 15 fibers/in. In Example 2, six polyester monofilaments with a wire diameter of 0.24 mmφ are twisted together at a twist rate of 2.0 twists/in to form the warp, and the same 0.7 mmφ polyester monofilament as in the past is used as the weft.
It is a herringbone filter cloth with a horizontal density of 40 fibers/in x 18 fibers/in. (Effects of the invention) Since the warp threads of the filter cloth according to the invention are composed of twisted threads of synthetic resin monofilament having a thin wire diameter and the same wire diameter, the vertical and horizontal densities are increased to prevent sludge from leaking. Even if the size is small, uniform water permeability can be maintained, and fine flocs of sludge can be separated from water. In addition, the composition single yarn of the twisted yarn is 0.1
Since it is a synthetic resin monofilament with a diameter of ~0.3 mm, the elongation of the filter cloth is small and single thread breakage due to abrasion is less likely to occur, resulting in a filter cloth that is resistant to mechanical tension and abrasion. Therefore, the filter cloth for a belt press type dehydrator according to the present invention has good water squeezing performance without leakage of sludge, and can perform filtration with high pressure and tension.

[Brief explanation of the drawing]

Figures 1a and b are respectively a surface perspective view and an enlarged sectional view of the warp of a filter cloth for a belt press type dehydrator according to the present invention, and Figures 2a and b are respectively for a belt press type dehydrator according to the prior art. FIG. 3 is a perspective view of the surface of a filter cloth, an enlarged sectional view of its warp, and FIG. 3 is a schematic side view of a belt press type dehydrator. 1... Warp, 2... Weft, 1F... Single filament yarn, 10... Conventional warp, 3... Filter cloth, 4...
Sludge, 5... Cake, 6... Gravity filtration section, 7...
Pressure dehydration section, 8... Shear compression dehydration section.

Claims (1)

[Scope of utility model registration request] In a filter cloth woven using synthetic resin monofilaments as warp threads, 3 to 50 synthetic resin monofilaments with the same wire diameter among the synthetic resin monofilaments with wire diameters of 0.1 to 0.3 mm are twisted together in the warp threads. A filter cloth for a belt press type dehydrator, characterized in that the twisted yarn is used.