JPH0240210A - Filter - Google Patents

Abstract

PURPOSE:Tc carry out filtration at high temp. and to prevent the damage of the title filter in the regeneration by combustion by spirally winding a conductive exothermic fiber on an electrical insulating porous cylindrical base body to form a filter, and electrically heating the fiber. CONSTITUTION:The substantially continuous conductive exothermic fiber 1 such as a conductive ceramic fiber is spirally wound on the porous cylindrical body 2 made of an electrical insulating ceramic, etc., and a couple of electrodes 3a and 3b are arranged on both ends to form a filter. A fluid to be filtered contg. solid particles of carbon, etc., is introduced into the filter from the outside, the solid particles are collected by the fiber 1, and the fluid freed of the solid particles is discharged from the hollow part of the base body 2. When the filter is regenerated, the electrodes 3a and 3b are connected to a power source 4 to energize the fiber 1, hence the fiber 1 is heated to a temp. higher than the combustion temp. of the deposited solid particles, and a gas contg. oxygen is simultaneously supplied to the filter to burn and remove the solid material.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to filters for fluids containing carbon and other combustible solids. More specifically, the present invention relates to a filter particularly suitable for filtering fluids at high temperatures and incinerating trapped solids at high temperatures.

[Prior Art] Filtration using a filter is a simple and most commonly used method for removing solid particles from a gaseous or liquid fluid to be filtered containing solid particles. When using this method, if the fluid to be filtered is at a high temperature and it is necessary to perform filtration at a high temperature, it is necessary to heat the container containing the filter base from the outside and strictly control the temperature to maintain a constant temperature. . In other words, in high-temperature filtration, unless the solids that are not filtered are removed at high temperature, the filtration time is short and it is difficult to regenerate the filter. The disadvantage is that there are few. The reason for this is that the filtered solids stick to the filter material or the solids come into contact with each other due to temperature changes during the filtration process. In such cases, the filter must be heated externally to maintain a constant filtration temperature.
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] However, controlling the filtration temperature at a high temperature, particularly 500°C or higher, and at a constant level requires fairly large-scale attached equipment, especially when the filtered solids are not required. Removal costs are high and uneconomical. In addition, when incinerating the filter during filter regeneration, a considerable amount of combustible solids accumulated on the filter self-combust one after another, resulting in a temperature of 15% during treatment.
There is a problem in that the temperature reaches as high as 00°C and the constituent materials of the filter are damaged.

The present invention aims to provide a novel filter that is suitable for such high-temperature filtration and that is not damaged by regeneration through filter combustion treatment.

[Means for Solving the Problem] The above problem is to provide a filter in which substantially continuous conductive heat-generating fibers are spirally wound around the outer periphery of a porous cylindrical base whose surface is electrically insulating at least. This is achieved by the filter according to the present invention, characterized in that electrodes are disposed at both ends of the filter so that the fibers generate heat when electricity is applied to the fibers.

The main part of the filter of the present invention is composed of a porous cylindrical substrate whose surface is electrically insulating at least, a conductive heating fiber wound around the substrate, and a pair of electrodes for passing current through the fiber. .

FIG. 1 is a front view showing an example of the filter of the present invention,
FIGS. 2(a) and (b) are cross-sectional views, respectively.
In the figure, 1 is a conductive heating fiber, 2 is a porous cylindrical substrate, and 3a and 3b are a pair of electrodes.

As the conductive heating fiber 1, conductive ceramic fiber is preferable, but heat-resistant metal fiber may also be used.

Examples of conductive ceramic fibers include fibers made of silicon carbide, molybdenum silicide, lanthanum chromate, titanium carbide, and zirconia. Silicon (silicon carbide) based fibers are particularly preferred because they have excellent electrical properties and heat resistance. It can be industrially advantageously produced by a method using a combination as a precursor. When producing this fiber, -TiO--ZrOB or the like may be introduced into the precursor polymer.

The appropriate thickness of the fiber is about 0.1 to 100 De in denier. The conductivity of the fiber is the specific resistance of a single fiber of 500~
10-4 to 103Ω at 1200°C, especially 10°
It is preferable that the winding density of the fibers on the substrate is 3 to 102 Ω・■, considering the filtration effect, and the mesh opening of m distance is 0.1.
The thickness of the rolled fiber layer can be selected appropriately, but it is generally preferred to have a thickness of 0.5 to 20 microns.

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

For example, a combination of silicon carbide fibers, titanium carbide fibers, or zirconia fibers may be used.

In either case, each fiber must be substantially continuous, and short fibers are not preferred because they have poor conductivity.

On the other hand, the porous cylinder 2 that becomes the base material around which the fiber 1 is wound is
At least the cylindrical surface (fiber-wrapped portion) is made of a heat-resistant material with electrical insulation properties, and is a fluid-permeable porous cylinder having communication holes with a coarser opening than the fiber layer. It is preferable that the cylinder 2 has a hollow part in the center as shown in FIG. 2. The fluid to be filtered is usually supplied from outside the fiber layer,
The solids are filtered through the fibrous layer, and the filtered fluid passes through the porous layer of the cylinder and is taken out from the hollow part provided in the center of the cylinder. Good too. Generally, electrically insulating heat-resistant ceramic is preferably used as the material for this porous cylinder 2, but other electrically insulating materials may also be used.
As shown in a), the entire body may be made of an electrically insulating material, or as shown in FIG. It can also be used by covering it with the material 2a.

The filter of the present invention is further provided with a pair of electrodes 3a and 3b at both ends for supplying electricity to the fiber 1 described above. These electrodes 3a, 3b are made of a heat-resistant metal having a lower electric resistance than the fiber 1, and usually silver, @, or an alloy thereof is used. Electrode 3a.

3b is preferably provided over the entirety of both ends as shown in FIG. 1, but may be provided partially as long as it is possible to energize the entire surface of the fiber and generate heat.

The electrodes 3a, 3b are connected to a power source 4 when necessary, so that current can be passed through the fibers on the surface of the filter.

[Function] In the filter of the present invention, the fluid to be filtered containing solid particles is usually introduced from the outside of the layer around which the fibers are wound, passes through the delamination a and the porous hollow cylinder, and reaches the center of the cylinder. During this time, solid particles are trapped in the fiber layer.

In this way, solid particles accumulate near the surface of the filter used for filtration, and when a suitable amount of accumulation is reached, use is stopped, the solid particles are removed, and the filter is reused. In the method for removing accumulated solid particles, if the solid particles are flammable, a power source is connected to the electrodes at both ends of the filter and current is passed through the fiber layer to cause the filter to generate heat above the combustion temperature of the solids. At the same time, by supplying oxygen-containing gas to the filter, solids can be burned and removed.

In another use of the filter of the present invention, when the fluid to be filtered needs to be filtered at a high temperature, the filter is maintained at a desired temperature by passing an electric current through the filter electrode to perform the filtration to remove solids. I can do it.

[Effects of the Invention] The filter of the present invention as described above can control filtration to a desired temperature by heating the fibers themselves when energized, and in removing filtered solids,
It is possible to heat the solid material to a temperature higher than its self-combustion temperature and burn it off by generating electricity.

Furthermore, in the filter of the present invention, by controlling the amount of filtered deposited solids, it is possible to maintain the combustion temperature below the filter's heat resistance temperature. The durability of can be significantly extended. It has this excellent effect.

[Example] SiC using a polycarbosilastyrene copolymer produced by the method described in U.S. Patent No. 4,743,411 as a precursor
Fiber (specific resistance at 1000℃=10″2Ω・CII
I) was rolled up in a spiral shape at an edge angle of 30 degrees with an opening of 50 μm in a hollow cylinder of electrically insulating porous ceramic with an outer diameter of 20 mm and a thickness of 480 mm, and a pair of copper electrodes were attached to both ends of the coil to connect it to the fiber. , a filter was made. This filter was used for filtering exhaust residue from a diesel engine. 2
After using the filter for a period of time, the supply of exhaust gas to the filter was stopped, and the electrodes of the filter were connected to a power source, and a current of 20 V was applied to heat the fibers of the filter to about 1000° C. At the same time, air was supplied to the filter. The carbon adhering to the fibers was incinerated and after about 3 minutes the filter was regenerated substantially free of carbon. When the exhaust gas was passed through this regeneration filter again, efficient filtration was possible.

[Brief explanation of the drawing]

The attached drawings illustrate embodiments of the present invention, and FIG. 1 is a front view of a filter according to the present invention, and FIGS. 2(a) and 2(b) are sectional views, respectively. 1 Exothermic fiber 2... Electrically insulating porous cylindrical substrate 2a... Electrically insulating porous layer 2b... Conductive porous cylindrical substrate 3a, 3b... Electrode 4... Power supply patent Applicant Teijin Ltd.

Claims (5)

[Claims] (1) A filter in which substantially continuous conductive heat-generating fibers are spirally wound around the outer periphery of a porous cylindrical base whose surface is electrically insulating at least, and when the fibers are energized, the fibers generate heat. A filter characterized by: (2) The opening between the spirally wound fibers is 0.1 to 50
The filter according to claim 1, which has a particle diameter of 0 microns (μm). (3) The filter according to claim (1), wherein the conductive heating fiber is a conductive ceramic fiber. (4) The conductive ceramic fiber has a silicon-carbon bond (-Si
The filter according to claim 3, which is a fiber made of ceramic whose main component is -C-). (5) As a conductive ceramic fiber, the specific resistance of the single fiber is 10^-^4 to 1 at a temperature of 500 to 1200°C.
Claim (3) using a material having a value of 0^3Ω・cm
) or the filter described in (4).