JPH0243914A - Filter - Google Patents

Abstract

PURPOSE:To make the title filter suitable for high temp. filtering by mainly bonding the fibers of a nonwoven fabric composed of conductive heating fibers by a conductive cellulose material to form a filter and electrifying the nonwoven fabric to make it possible to generate heat. CONSTITUTION:Nonwoven fabrics 1a, 1b composed of conductive heating fibers (e.g., silicon carbide fibers based on a silicon-carbon bond) having a length/ diameter ratio of 100 or more are formed ito a filter layer. The fibers of said nonwoven fabrics are mainly bonded by a conductive ceramic material (e.g., lanthanum chromate): electrodes 3a, 3b are arranged to two opposed sides of the filter layer and the nonwoven fabrics are electrified to make it possible to generate heat. This filter is suitable for high temp. filtering and not damaged at the time of regeneration by the burning treatment of the filter.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is suitable for filtering fluids at high temperatures and regenerating filters by incinerating trapped combustible solids at high temperatures. It's about filters.

[Prior Art] In order to remove particles from a gas or liquid to be filtered fluid containing solid particles, it is necessary to use a filter medium that has pores that are smaller than the particles to be separated, or that the particles are cross-linked over the pores. It is necessary to reduce the size of the holes. The filter media used in such filtration processing are collectively referred to as filters. A filtration operation using a filter is the simplest and most commonly used method for separating particles from a gas or liquid containing solid particles.

In this method, when the filtration process is performed at a constant temperature higher than room temperature, especially when the fluid to be filtered is at a high temperature and the filtration process also needs to be performed at a high temperature, the container containing the filter base is kept at a constant temperature by an external The temperature must be controlled by heating.

For example, when solid particles are useful, if there is a change in temperature during the filtration process, the filtered solid particles may stick to the filter or the solids may crosslink and fuse together, resulting in a decrease in the yield of solid particles. This is because the downside is that the usable time of the filter is short, and sometimes it becomes difficult to regenerate the filter. When the filtration temperature is as high as 500° C. or higher, changes in the filtration temperature often impair the desired properties and physical properties of the solid particles.

Therefore, controlling the filtration temperature at high temperatures is extremely important.

Furthermore, in filtration where solid particles are not required, it is practically important that the filter can be reused.

If the solid is combustible, methods of recycling include incinerating the used filter in a combustion furnace, or adding fuel and burning it. As mentioned above, in high-temperature filtration, solids often stick to the filter and regeneration is difficult, and in this case the filter has no choice but to be disposable.

[Problems to be Solved by the Invention] Controlling the filtration temperature to a temperature higher than room temperature, particularly at a constant temperature of 500°C or higher, is characterized by fairly large-scale incidental equipment, especially when filtered solid particles are not required. The removal cost is high and it is uneconomical.

In addition, when recycling filters by incineration, a considerable amount of combustible solids deposited on the filter base self-combust one after another, resulting in the filter itself reaching a temperature of 1500°C during the regeneration process, damaging the constituent materials of the filter base. There is a problem with doing so.

The present invention is suitable for high-temperature filtration at such high temperatures, and
The present invention aims to provide a new filter that will not be damaged by regeneration through filter combustion treatment.

[Means for Solving the Problems] The above problem is to provide a filter having a filtration layer made of a nonwoven fabric substantially made of conductive heat-generating fibers having an L/D of 100 or more, in which the fibers in the nonwoven fabric are mainly conductive. This is achieved by the filter of the present invention, which is fixed with a ceramic material and has electrodes arranged on two opposing sides of the filter so that the nonwoven fabric generates heat when electricity is applied to the nonwoven fabric. .

The filtration layer in the filter of the present invention is mainly L/
It is constituted by one or more short fiber nonwoven fabrics or IIN nonwoven fabrics consisting essentially of conductive heat-generating IIN in which D is 100 or more.

As the conductive heat-generating fiber, conductive ceramic fiber is preferable, but heat-resistant metal fiber may also be used. Conductive ceramic materials include silicon carbide, molybdenum silicide,
There are $8 fibers such as lanthanum chromate, titanium carbide, and zirconia, but among them, silicon carbide II, whose main component is a bond between silicon and carbon (-8+ -C-), has excellent electrical properties and heat resistance. It is particularly preferable because it is excellent in both. Such fibers can be advantageously produced industrially, for example, by the method described in US Pat. No. 4,743,414, using a polycarbosilastyrene copolymer as a precursor. When producing this fiber, -rio-, -zr O-, B, etc. may be introduced into the precursor polymer.

Appropriate thickness of the m-sized wire is about 0.1 to 100[)e in denier. The electrical conductivity of the fiber is as follows: the specific resistance of a single fiber is 500
It is preferable that it is 10→~103Ω·cps at ~1200°C.

The cross section of Ivi is not limited to the usual circular shape, but may be non-circular, such as a cocoon shape or a trilobal shape. Further, two or more types of conductive fibers may be used in combination as long as they have sufficient heat resistance.

For example, silicon carbide mm and titanium carbide 1
It can also be used in combination with lft and zirconia 119&.

Non-woven fabric composition 41 The strip may be short or long fibers, but it is short!
! Even in the case of roughness, it is necessary that L/D (length/diameter ratio) is 100 or more, preferably 1000 or more, and L
If /D is smaller than this, the conductive performance of the nonwoven fabric will be poor.

Even if the fiber weighs 100 g or more, iIN alone is insufficient in conductivity, so in the present invention, the fibers constituting the nonwoven fabric are fixed at intervals of m with a conductive ceramic material. In addition to the fiber constituent materials mentioned above, examples of this conductive ceramic material include:
Lanthanum chromate, R tri.

Ram can also be used.

To produce such a nonwoven fabric, a conductive ceramic precursor polymer, such as a polycarbosilastyrene copolymer, was melt spun and wound onto a bobbin! After the material is infusible while wound on a bobbin or unwound from the bobbin, it is made into a sheet (web), and the sheet is coated with the ceramic precursor polymer (for example, polycarbosilastyrene copolymer) or It can be manufactured by impregnating it with the solution and then firing it.

In manufacturing a nonwoven fabric, it is of course possible to use two or more types of fibers together; for example, it is possible to mix two or more types of conductive ceramic fibers, or to mix conductive ceramic I miscellaneous materials and metal II miscellaneous materials. and can also be used. Furthermore, non-conductive fibers having heat resistance may be used in combination without impairing the conductive performance of the nonwoven fabric.

The above nonwoven fabric is made of conductive ceramic l! It can also be used in a laminated manner with a woven fabric made of other materials, or it can be used in a laminated manner with an electrically insulating sheet that has greater fluid permeability than the nonwoven fabric.

In the filter of the present invention, the filtration layer as described above may be supported by a fluid-permeable support such as a large porous plate or a wire mesh.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a simplified cross-sectional view of one embodiment of the filter of the present invention. In the figure, 1a and lb are nonwoven fabrics made of conductive heat-generating fibers, and 2 is a conductive heat-generating continuous l! The non-woven fabrics 3a, 3b can be connected to a power source 7 by means of a pair of electrodes for passing current through these non-woven fabrics and woven fabrics.

4a and 4b are supports made of a pair of heat-resistant porous plates for fixing a filtration layer made of a nonwoven fabric and a woven fabric, and the filtration layer is sandwiched and fixed by these supports 4a and 4b. The material of these supports is preferably electrically insulating. The fluid to be filtered is supplied to the filter through conduit 5, passes through the filtration layer and support layer as shown by the arrow, and is discharged through conduit 6.

[Action/Effect] The filter of the present invention has nonwoven fabrics 1a and 1b (and woven fabric 2).
) When the electrodes 3a and 3b provided at both ends of the nonwoven fabric (and the woven fabric) are connected to a power source 7, heat is generated in the nonwoven fabric (and the woven fabric), and if filtration is performed in this state, high-temperature filtration can be performed. Furthermore, when used to filter a fluid containing combustible solid particles, the combustible matter deposited on the filter can be incinerated and removed simply by applying electricity after use, making it easy to regenerate. Moreover, the regeneration processing temperature can be maintained within a constant temperature range by controlling the current on/off or the current value.
It has the advantage that it is not exposed to extremely high temperatures such as 00°C, and the filter is less likely to be damaged by high temperatures during regeneration processing.

[Brief explanation of the drawing]

FIG. 1 is a simplified cross-sectional view showing one embodiment of the filter of the present invention. 1a, 1b... Non-woven fabric of conductive heat generating fibers 2... Woven fabric of conductive heat generating 11 miscellaneous fabrics 3a, 3b... Electrodes 4a, 4b... Support body

Claims (1)

Scope of Claims: (1) A filter whose filtration layer is a nonwoven fabric made essentially of conductive heat-generating fibers with an L/D of 100 or more, wherein the fibers in the nonwoven fabric are mainly fixed with a conductive ceramic material. 1. A filter characterized in that the nonwoven fabric is made to generate heat by arranging electrodes on two opposing sides of the filter and applying electricity to the nonwoven fabric. (2) The filter according to claim (1), wherein the filtration layer is formed by stacking a large number of conductive heat-generating fiber nonwoven fabrics. (3) A filtration layer is formed by laminating a conductive heat-generating fiber nonwoven fabric and a woven fabric made of conductive heat-generating continuous fibers.
The filter described in section 1). (4) The conductive ceramic fiber has a silicon-carbon bond (-Si
The filter according to claim (1), (2) or (3), which is silicon carbide fiber containing -C-) as a main component. (5) The filter according to claim 1 or 4, wherein the filtration layer is formed by alternately laminating one or more layers of conductive heat-generating fibrous nonwoven fabric and fluid-permeable electrically insulating sheets. (6) The filter according to any one of claims (1) to (5), wherein the filtration layer is laminated with a support layer that is permeable to the fluid to be filtered.