JPH0730106Y2 - High temperature dust collection filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a high temperature dust collecting filter.

[Conventional technology and its technical problems]

A filter dust collector is widely used as a means for preventing air pollution. This filter dust collector separates and collects suspended particles such as dust by passing a dust-containing gas through a filter medium, and therefore its performance is greatly influenced by the filter medium.

Conventionally, as this type of filter material, cotton, hemp, natural fibers such as cellulose, inorganic fibers such as glass fibers, polyamide-based,
Filter cloths made of synthetic fibers such as polyester, acrylic, polypropylene and polyfluorocarbon have been used. However, even if they have the highest practical heat resistance temperature, they are 200 to 250 ° C. Therefore, for example, high temperature dust-containing gas such as boiler exhaust gas, municipal waste incinerator exhaust gas, kyupora exhaust gas, clinker cooler exhaust gas for cement production cannot be collected accurately, and the service life is short even when used below the limit temperature. was there. In addition, there is an economic problem that a facility for cooling the dust-containing gas is required and the high temperature exhaust gas cannot be effectively used.

On the other hand, recently, gases emitted from metallurgical equipment such as blast furnaces, converters, and electric furnaces, as well as exhaust gases from coal gasification power generation systems, have high temperatures such as 300 to 1000 ° C or higher, and There is an increasing demand for high performance dust collection under high pressure conditions such as atmospheric pressure to 10 atmospheres or more.

BACKGROUND ART Heretofore, a ceramic filter made of silica, alumina, zirconia, boria, magnesia, silicon carbide, or the like has been known as a filter medium for collecting dust of exhaust gas exceeding 300 ° C. This filter has good heat resistance. However, there is a lot of clogging inside the porous body, resulting in high pressure loss, and through holes (open pores).
There is a problem that the desired performance cannot be obtained under high pressure conditions because the flow rate is small at the same pressure because the porosity is small and the porosity is small. In addition, it is difficult to join, it is difficult to process because it is a hard and brittle material, the weight is heavy,
In addition, there was a problem in that it was vulnerable to impact and easily damaged.

For high temperature exhaust gas dust collection, woven fabric of metal fiber,
There is a metal filter using a non-woven fabric, felt, or a sintered plate. However, in the conventional metal filter, since short metal fibers are simply dispersed and bonded with a binder or without a binder, it is difficult to achieve both the collection rate and both the pressure loss and clogging factors, and the dust filter is also used. There was a problem that it was impossible to facilitate the payment.

The present invention was devised to solve the above-mentioned problems, and an object of the present invention is to provide a metal fiber porous sintered filter media type dust collecting filter having good dust collecting performance for high temperature dust-containing gas. To provide.

[Means for Solving the Problems]

In order to achieve the above object, the present invention comprises a metal short fiber sintered layer having good heat resistance and a metal long fiber sintered layer having good heat resistance, which are integrated in the thickness direction. Is a composite sintered porous filter medium in which the fibers of the long metal fiber sintered layer have a relatively small diameter.

The short metal fiber sinter layer and the long metal fiber sinter layer are preferably composed of plates, and the sinter plates are polymerized and fusion-bonded by sintering, and the short metal fibers have an average diameter of 20 to 200 μm. Yes,
The diameter of the long metal fibers is preferably in the range of 1/2 to 1/20 of the diameter of the short metal fibers. Further, the heat-resistant metal mesh may be bonded to at least one side surface of the composite sintered plate of the metal short fiber sintered layer and the metal long fiber sintered layer.

The matrix material of the sintered metal short fiber layer is preferably a fiber made by the chatter vibration cutting method, and the matrix material of the sintered metal long fiber layer is preferably a fiber made by the convergent drawing method.

The filter according to the present invention is a cylindrical candle filter,
It can be applied to various types of filters such as cross-flow filters and flat or envelope filters.

〔Example〕

 An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a high temperature dust collecting filter according to the present invention, and FIG. 2 shows another embodiment. In FIG. 1, reference numeral 1 is a cylindrical filter medium body, and the filter medium body 1 is, as shown in FIGS. 3 (a) and 3 (b), a metal short fiber sintered layer 1a of an inner layer and a metal long fiber of an outer layer. And a sintered layer 1b, which are laminated and integrated in the thickness direction. Reference numeral 2 is a bottom plate welded to the lower end of the filter body 1, and 3 is a flange welded to the upper end. In the filter medium body 1, the flange 3 is passed through the cell plate 6 via the packing 7, and the venturi 8 and the bolt 9
It is suspended by being tightened with. For example, the pulse nozzle 4 is desired as the backwash means for the venturi 8.

The dust-containing gas A is pressed in from the outer peripheral side of the long metal fiber sintered layer 1b, and the clean gas after dust collection flows out from the opening 5 of the short metal fiber sintered layer 1a through the venturi 8. The dust is collected by the long metal fiber sintered layer 1b on the outer surface and the dust primary adhesion layer B ', and forms a dust cake. The dust cake layer B is backwashed from the clean side, that is, the short metal fiber sintered layer side by the injection of the compressed gas from the pulse nozzle 4 and the ejector effect by the venturi 8 with the differential pressure or the timer as a parameter.

The metal short fiber sintered layer 1a is coarser than the metal long fiber sintered layer 1b,
It is thick and highly rigid and fulfills the backup function in addition to the function as a filter medium. On the other hand, the long metal fiber sintered layer 1b is a main filter medium, and is dense, thin, and has a smooth surface, so that it exhibits good dust removal performance. The layer thickness thereof is appropriately selected according to the strength and gas pressure required as a filter, and for example, the metal short fiber sintered layer 1a is 0.5 to.
2.0 mm, and the long metal fiber sintered layer 1b is 0.2 to 0.6 mm.

Then, preferably, as shown in FIG. 3 (a), a mesh body 1c is integrated as a support layer on the surface of the sintered metal short fiber layer 1a. If necessary, as shown in FIG. 3 (b), a fine mesh body 1c 'may be integrated on the surface of the long metal fiber sintered layer 1b. The mesh bodies 1c and 1c 'include a wire mesh and punching metal.

Although the whole filter medium body 1 may be configured by a single cylinder,
It may be configured by connecting a plurality of cylinders having a required length. FIG. 2 shows an embodiment thereof, in which cylindrical element bodies 10 and 10 'are butted up and down and connected by welding 11, and a heat-resistant metal ring 12 having a length extending over the connection area is fitted on the inner surface side. It fits. According to this structure, a long filter can be easily obtained, and the refractory metal ring 12 prevents bending due to variable internal pressure. When a plurality of heat-resistant metal rings 12 are provided above and below, they may be connected to each other by a vertical bar.

The metal short fiber sintered layer 1a, the metal long fiber sintered layer 1b, and the mesh 1c are made of stainless steel, Kanthal, nickel,
It is made of heat-resistant metal or alloy such as Inconel, Hastelloy, and copper. The metal short fiber sintered layer 1a, the metal long fiber sintered layer 1b, and the mesh bodies 1c and 1c 'are usually made of the same material, but may be made of different materials depending on the case.

The short metal fibers a constituting the matrix of the short metal fiber sintered layer 1a have a coarse diameter, that is, a converted diameter of 20 to 200 μm on average, and an aspect ratio (l / d) of 30 to 60 have porosity and mechanical strength. It is suitable from the point of. On the other hand, a long metal fiber sintered layer
As the metal long fibers b forming the matrix of 1b, those having a converted diameter relatively smaller than that of the metal short fibers a are used.

The reason is not only changing the porosity between the inner layer and the outer layer,
This is because the dust-containing gas is caused to flow from the outer layer having a fine mesh to the inner layer having a coarse mesh to reduce pressure loss and prevent dust from entering the inside of the filter medium as much as possible. Specifically, it is selected according to the diameter of the dust in the dust-containing gas within the range of 1/2 to 1/20 with respect to the diameter of the metal short fiber a. This is, for example, 2 to 30 μm on average. If the fiber diameter is too small, the pressure loss becomes large, and the strength against heat becomes poor. In addition, the cost of fiber production is high. Therefore, the lower limit should be 2 μm. Aspect ratio is typically 2500-50
A range of 00 is suitable.

As the metal short fibers a, whiskers, cut foils, etc. may be used, but cut fibers are preferably used. There is also a wire cutting method as this cutting method, but the chattering cutting method is most preferable because it has no material restrictions and does not require secondary processing (cutting). In this method, a cylindrical or rod-shaped metal block is cut (turned) using an elastic tool with a natural frequency of 500 to 5000 Hz, and the fiber is cut and created by the tool's self-excited vibration. It is a needle-like short fiber that has a triangular cross-sectional shape that is coincident with the blade length and is perpendicular to the longitudinal direction, has a large surface area, and has a uniform thickness, and has good strength due to work hardening.

On the other hand, as the long metal fiber b, a melt spinning method or a wire cutting method may be used, but generally, a drawing method, especially a convergent drawing method is preferable from the viewpoint of strength and cost.

The method for obtaining the filter body 1 is arbitrary. The metal short fiber sintered layer 1a, the metal long fiber sintered layer 1b, and the mesh body 1c may be made at once by one sintering, or the metal short fiber sintered layer 1a and the metal long fiber sintered layer 1b are separately formed. Alternatively, they may be reheated to form a composite. In the case of the former, for example, the tow of the long fiber base material is opened to form a web, on which the metal short fibers a are dispersed in a layered manner in a predetermined orientation by a disperser, and the reticulate body 1c is arranged. Sintering may be performed under pressure or under pressure in a vacuum or in a non-oxidizing atmosphere. In the latter case, the long fibers and the short fibers may be sintered in separate steps. In any case, although the sintered shape is arbitrary, it is generally a plate (including a curved plate or a groove plate). In the latter case, the sintered metal short fiber plate and the sintered metal long fiber plate are polymerized and reheated, preferably under pressure. As a result, the fibers that have come into contact with each other are fused and integrated with each other. The reticulate body 1c is preferably integrated by sintering when producing a short metal fiber sintered plate.

The shape imparting (including welding) as the filter medium may be performed after the composite is formed. That is, in the case of a tubular shape, after obtaining a composite plate having a cross section as shown in FIG. 3, it may be formed into a cylindrical shape by pressing or the like, the abutting portion is seam welded, and then the bottom plate and the flange are welded. In the case of the structure shown in FIG. 2, when the tubular element body 10 or 10 'is obtained, it is preferable that the half of the heat-resistant metal ring 12 is fitted into the opening and welded.

Of course, a shape may be given as a filter medium before the composite. That is, for example, a metal short fiber sintered layer 1a and a metal long fiber sintered layer 1b are prepared by a method such as filling a mold with a ring-shaped cross section with fibers and applying pressure, or using a double-tube type burnable mold.
From the beginning, a cylindrical sintered body may be used.

The present invention is not limited to the case where the metal short fiber sintered layer and the metal long fiber sintered layer are each a single layer. For example, two or more short metal fiber sintered plates are polymerized and integrated, and one metal long fiber sintered plate is joined and integrated, or conversely, two or more metal long fiber sintered plates are polymerized and integrated. , It 1
It also includes joining and integrating with one sheet of short metal fiber sintered plate. In addition, one metal short fiber sintered plate and one metal long fiber sintered plate may have a laminated structure of 2 to 3 layers having different fiber densities.

Next, specific examples of the present invention and results of comparative tests will be shown.

FIG. 4 shows an outline of the test apparatus. The reason for conducting this experiment is as follows. Usually, in a bag filter, dust is filtered by the surface layer of the filter medium. The filtration performance and pressure loss are composed of the air permeability of the filter medium, the pressure loss of the dust layer remaining on the filter medium even after the filter is removed, and the pressure loss of the dust cake layer deposited on the filter medium surface during filtration. The dust cake layer has a specific resistance value that is not affected by the filter medium. Therefore, an important factor in evaluating the pressure loss characteristics of the filter medium is the pressure loss immediately after the filter is removed. This is because how to reduce this value under the same load condition reduces the dust collection pressure loss of the filter medium and can be evaluated as the filter characteristic.

In the test apparatus, 50 is a compressed air supply pipe for dispersion, which is connected to a can body 51 of the test machine. 52 and 53 are test machine cans 51
Are two filters arranged in. 54 is an ejector inserted at the end of the compressed air supply pipe 50 for dispersion, 55 is a dust supply feeder provided in a branch pipe extending in a direction perpendicular to the axis of the compressed air supply pipe for dispersion, and 56 is compressed air supply for dispersion. It is a dispersion plate arranged in front of the opening of the tube.

The filters 52, 53 have venturis 520, 530 on their upper portions, and the lower portion thereof is supported by the partition plate 510 of the test machine can body 51, and the detection part of the differential pressure gauge 57 faces the venturi side and the filter side.

A compressed air tank 58 is arranged outside the upper part of the test machine can 51, and a pulse valve 61, is provided to each venturi 520, 530.
The pulse nozzles 59 and 60 controlled by 62 are facing.

An exhaust pipe 63 is connected to the side of the venturi side, a suction blower 71 is connected to the end of this via the air volume adjusting valves 69 and 70, and a flow meter via an orifice 64 in the middle of the exhaust pipe 63. 65 is provided, and a dust concentration measuring device 66 is provided downstream from this, a suction pump 67 and a dust concentration measuring nozzle.
Incorporated through 68.

The filter with the following specifications was used.

1. The filter of the present invention has a cylindrical composite sintered body with a bottom plate (outer diameter 140 mmφ, length 180
mm).

Outer layer (metal long fiber sinter): Material stainless steel, thickness 0.4mm, base material Convergent stretching method long fiber (average diameter 8μm, length 50mm) Inner layer (metal short fiber sinter): material stainless steel, thickness 1.6mm, short fibers by base material chattering cutting method (average diameter 30μm, length 1.5mm) Reticulate body: Stainless steel wire mesh, thickness 0.5mm, mesh size 60 mesh 2. Comparative example 1… Shaped cylinder (Outer diameter 165 mmφ, length 1920 mm) Specifications: Polyester non-woven fabric, thickness 1.5 mm, fiber diameter 15 μm Part 2… Shape tubular type (outer diameter 165 mmφ, length 1920 mm) Specifications: Metal fiber woven cloth, thickness 1.0 mm, fiber Diameter 8 μm Part 3… Cylindrical shape (outer diameter 100 mmφ, length 1800 mm) Specifications: Metal fiber single-type sintered plate, thickness 1.5 mm, fiber diameter 20 μm In the test, compressed air was introduced to ejector 54, and dust supply device
The dust supplied in a fixed amount from 55 was sucked and dispersed together with the outside air, further dispersed by the dispersion plate 56, and filtered by the filters 52, 53. The flow rate of the clean air after filtration was measured by an orifice differential pressure type, and after measuring the dust concentration, it was exhausted by a blower.

The pulse jet method was used for the cleaning, and the online pulse method was used to control the pressure loss of each filter when the pressure loss of each filter reached 100, 200, 300 mmAq.

Dust is JIS test powder fly ash 10 types (average particle size 5.2
μm) was used, and the supply amount was unified under the load condition of 50 g / m ³ . The filtration speed of the filter medium was in the range of 0.5 to 2.0 m / min, and the pressure loss of the filter medium immediately after the filter medium was removed, the dust removal cycle time, and the dust outlet concentration were measured for each filter medium. The results are shown in FIGS. 5 (a) (b) (c). (A) is 100mmA
q control, (b) 200 mmAq control, (c) 300 mmAq control.

As is clear from FIG. 5, the pressure loss of the filter medium immediately after being blown off of the present invention shows a low value for the same speed, and this tendency shows that when the pressure loss of the filter medium is set high and the filtration speed is high. It is remarkable when it is raised. From this, it can be seen that the present invention has excellent filtration performance even under high pressure conditions.

Based on these results, the present invention and Comparative Examples 2 and 3 have a high temperature exhaust gas of 300 ° C, a filtration speed of 1 m / min, and a dust removal pressure control 2
Dust was collected at 00 mmAq with an average particle size of 3 μm and an inlet dust concentration of 10 g / m ³ . As a result, the present invention had a dust collection rate of 99.98%, Comparative Example 1 had 99.90%, and 2 had 99.50%.

[Effect of device]

According to the dust collecting filter of the present invention described above, since the material is a metal fiber porous sintered body, it has excellent heat resistance and good mechanical strength, and is therefore thinner than a ceramic porous filter medium. The weight can be significantly reduced.

Furthermore, in terms of performance, since it has a deep layer structure with a high porosity that combines a metal long fiber sintered layer with a small diameter and a metal short fiber sintered layer with a larger diameter than that, there is little pressure loss and gas flow rate is reduced. Can be large. Moreover, since the dust-containing gas escapes from the fine metal long fiber sintered layer side to the coarse metal short fiber sintered layer side, the ratio of dust entering the inside of the filter medium is small and clogging can be reduced. Since the inner layer has a larger pore diameter, the pressure loss in this portion can be reduced. The inner layer reinforces the outer long metal fiber sintered layer, and since the outer layer has a smooth surface, dust can be easily removed. Therefore, not only high temperature dust collection,
It is possible to provide a dust collecting filter having excellent high-temperature and high-pressure dust collecting performance and good maintenance.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a high temperature dust collecting filter according to the present invention, FIG. 2 is a partial sectional view showing another embodiment, and FIGS. 3 (a) and 3 (b) are filter medium bodies according to the present invention. 4 is a partially enlarged view of FIG. 4, FIG. 4 is a schematic explanatory view of a performance test device, and FIG.
(B) and (c) are graphs showing a comparison of the pressure loss after dust removal of the filter of the present invention and another filter. 1 ... Filter body, 1a ... Metal short fiber sintered layer, 1b ... Metal long fiber sintered layer, 1c ... Net, a ... Metal short fiber, b ...
… Metal filaments

Claims (5)

[Scope of utility model registration request] 1. A metal short fiber sintered layer having a good heat resistance and a metal long fiber sintered layer having a good heat resistance are integrated in the thickness direction. A high temperature dust collecting filter characterized in that the fibers of the tie layer are configured to have a relatively small diameter. 2. A utility model registration claim 1 in which the metal short fiber sintered layer and the metal long fiber sintered layer are plates, and these sintered plates are polymerized and fusion-bonded by sintering. High temperature dust collection filter. 3. The utility model registration claim 1 or 2, wherein the diameter of the short metal fibers is 20 to 200 μm on average and the diameter of the long metal fibers is in the range of 1/2 to 1/20 of the short metal fiber diameter. The high temperature dust collecting filter according to any one of item 2. 4. A metal short fiber sinter layer and a metal long fiber sinter layer each comprise a plate, and these sinter plates are polymerized and fusion-bonded by sintering, and at least one side surface is made of a refractory metal mesh. The high temperature dust collecting filter according to claim 1, wherein the utility model is registered as a utility model. 5. A utility model registration claim in which the metallic short fibers are fibers produced by the chattering vibration cutting method and the metallic long fibers are fibers produced by the convergent drawing method. High temperature dust collecting filter described in.