JPH08196827A - Filter medium of regenerative air filter device - Google Patents

Abstract

PURPOSE: To obtain an air filter medium having high efficiency of capturing of fine dust by using pile consisting of fibers of different thicknesses as a filter layer. CONSTITUTION: Pile consisting of 30-40% thick fibers 3 of >35μm fiber diameter and the balance thin fibers 4 is formed on meshy base cloth at an angle to the surface of the base cloth. Strength necessary for vacuum suction and regeneration is maintained by the thick fibers 3 and the efficiency of capturing of fine particles is enhanced by the thin fibers 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter medium regenerating type air filter medium.

[0002]

2. Description of the Related Art As an air filter, in order to save labor and resources for exchanging and regenerating filter media, for example, a suction nozzle provided close to the surface of the filter media is connected to a suction device such as a vacuum cleaner. Recently, a so-called vacuum suction type automatic regenerating filter for suctioning and removing dust adhering to the surface of the filter medium has come to be widely used. In this case, what is used as a filter material is a mesh base cloth having a pile formed as a filter layer on the surface thereof as shown in Fig. 1 (a). In many cases, the fibers were uniformly adhered by the electro-implantation method, or the mesh of the base cloth was knitted by knitting or the like and the pile was knitted so as to project above the mesh.

However, all the piles of these filter media are made of fibers of uniform thickness as shown in FIG. 1 (b). As a filter media for a fiber layer air filter, it is suspended in the atmosphere according to its filtering theory. In order to increase the collection efficiency for the fine dust that is generated, it is necessary to reduce the thickness of the filter media fiber, but in electrostatic flocking, if the fiber is thin, the length of the fiber that can be flocked becomes shorter, and it becomes difficult to filter. There is a problem in that the required fiber layer density cannot be obtained, and as a result, the collection efficiency is reduced. Further, electrostatic flocking has a drawback that the pile falls off from the base cloth due to suction friction by the vacuum suction nozzle during regeneration.

Further, in the case of the one made by weaving into the mesh base cloth, the pile does not fall off, and the length of the pile can be freely increased, but the pile of fine fibers has a weak waist and the surface is repeatedly sucked by the vacuum suction nozzle. When a force such as rubbing is applied to the fibers of the pile, the fibers of the pile are entangled with each other, so that a space is partially formed on the surface of the filter medium, and both the pressure loss and the collection efficiency decrease. Therefore, conventionally, the pile was composed of only thick fibers having a fiber diameter of 35 μm or more, and the collection efficiency for fine particles could not be increased.

[0005]

A problem to be solved is that a pile of fibers having a uniform thickness cannot obtain sufficient collection efficiency for collecting fine particles such as atmospheric dust.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a suction nozzle or the like is constructed by constructing a pile protruding on a mesh base fabric with a plurality of thick fibers having a fiber diameter of 35 μm or more and fibers thinner than that. We have achieved the purpose of maintaining sufficient waist strength to withstand the friction of and also increasing the collection efficiency even for fine dust with fine fibers.

[0007]

EXAMPLE FIG. 2 shows one example of the filter medium of the present invention.
Is a reticulated base cloth having an opening area of about 1 to 4 mm, 3 is a pile of thick fibers, 4 is a pile of thin fibers, 2 or more kinds of fibers having different thicknesses are mixed and woven into the base cloth, and the root is also Are fixed and protruded above the base cloth surface to form a fiber layer filter, which is the main subject of the present invention.

As has been theoretically clarified, the dust collecting action of the fiber layer air filter is due to the fact that the particles collide and adhere to the fibers due to gravity, inertial force, diffusing force, electrostatic force, etc. acting on the dust particles. However, the filter medium of the present invention is intended to be used for general air conditioning for air dust and the like, and the trapping action in this case is dominated by inertia collision and diffusion interruption. The inertial collision of particles with one fiber, i.e., a single fiber, which constitutes the fiber layer air filter, is caused by the inertia of the particles that have come on the streamline due to the rapid change of streamline in the vicinity of the fiber. It occurs when the fiber falls off the streamline and hits the fiber. The Stokes number S _tk shown in Eq. 1 is a parameter that determines the degree of inertial collision of particles. In addition, the fine particles deviate from the streamline of the air flow, move in a motion called Brownian diffusion, and collide with the fibers to be collected. This collection action is called diffusion barrier, and the magnitude of the collection effect is a function of the number of diffusion parameters 2. It has been theoretically clarified that the higher the value of each of these parameters, the higher the collection efficiency.

[0009]

[Equation 1]

[Equation 2] Here, τ is a characteristic value called relaxation time, U _o is surface wind velocity, d _f is fiber diameter, ρ _p is particle density, d _p is particle diameter, C _c is Cunningham's correction coefficient, and η is air. Viscosity of, κ
Is the Boltzmann constant, and T is the absolute temperature.

It has been shown from the above Equations 1 and 2 that the d _{St, that} is, the smaller the fiber diameter, the greater the Stokes number and the diffusion parameter. Will be possible. However, if the fibers of the pile are made thinner, the stiffness becomes weaker, and when rubbing the pile surface with a vacuum suction nozzle during regeneration, the fibers are entangled with each other, creating a space on the filter surface, and the collection efficiency and pressure loss both decrease. There is. In order to prevent this defect, it is necessary to make the fiber diameter of the pile 35 μm or more. With a pile of a single thickness, the pressure loss is kept below 12 mm in the water column at a wind speed of 2.5 m / s, and JIS 8 type dust is used. Was limited to 50% of the collection efficiency for.

The filter material of the present invention comprises a pile of two or more kinds of fibers having different thicknesses formed on a mesh-like base cloth, so that a filter material of a conventional pile using one kind of fibers ( We succeeded in obtaining an air filter medium that has a higher collection efficiency than that in Fig. 1 (b) and at the same time does not cause performance deterioration due to entanglement of pile fibers due to friction during regeneration by a vacuum suction nozzle. It is useful for expanding the applications of regenerative air filters.

The air-conditioning air filter requires the use of a flame-retardant filter medium in order to prevent a fire when an object that becomes a fire source such as cigarette butts is sucked from the air intake port of the air-conditioning system. However, in the filter medium of the present invention, a flame-retardant filter medium can be obtained by using flame-retardant fibers such as polyclar, modacrylic, or vinylidene chloride for the base cloth and pile.

[0013]

As described above, the air filter medium of the present invention keeps the required waist strength by thick fibers, and in addition, by the thin fibers constituting the pile, the collection efficiency for fine particles is obtained. Has the effect of increasing the FIG. 3 shows a fiber diameter of 20 μm, 27 μm, 35 as one embodiment of the present invention.
A collection efficiency curve for the particle size of dust at a wind speed of 2.5 m / s in the case of a pile using three types of fibers of μm. For comparison, in the case of a conventional pile with a single thickness of about 35 μm The curve of B is also shown. Further, FIG. 4 is a comparison of the collection efficiency by the gravimetric method using JIS type 8 dust, and each shows the effect of the present invention.

[Brief description of drawings]

FIG. 1 is an explanatory view of a conventional pile filter medium that does not use the present invention, in which (a) is a perspective view and (b) is a sectional view.

FIG. 2 is a cross-sectional explanatory view of a pile filter medium according to one embodiment of the present invention.

FIG. 3 is an explanatory diagram showing the effect of the present invention.

FIG. 4 is another explanatory diagram showing the effect of the present invention.

[Description of sign]

 DESCRIPTION OF SYMBOLS 1 Reticulated base fabric 2 Pile fiber (pile) 3 Pile of thick fiber 4 Pile of thin fiber A Collection efficiency characteristic curve of one example of the filter medium of the present invention B Collection efficiency characteristic curve of conventional filter medium

Claims (3)

[Claims] 1. A filter medium for gas filtration, comprising a mesh-like base cloth and napped fibers (hereinafter referred to as piles) woven into the base cloth and protruding above the surface of the base cloth to form a brush-like filter layer. A filter material for gas filtration, comprising a plurality of fibers having a diameter of 35 μm or more and a plurality of fibers having a diameter smaller than that of fibers having different diameters. 2. A filter medium for gas filtration, wherein the pile according to claim 1 is inclined with respect to the surface of a mesh-like base cloth, and the napped fiber group covers the mesh of the base cloth to form a fiber layer air filter. 3. A filter medium for gas filtration, wherein both the mesh base fabric and the pile of claim 1 are made of flame-retardant chemical fibers.