JP2021058852A - High-temperature dust collection ceramic filter element - Google Patents

Abstract

To provide a high-temperature dust collection ceramic filter element that has thermal shock resistance in a wide temperature range, has excellent handling performance, has strength and a structure which can withstand vibrations or the like, has a degree of freedom of design which enables dust removal performance and pressure loss to be changed, and can prevent occurrence of clogging.SOLUTION: Preferably, a ceramic filter element is used as base materials integrated bodies in which one or more kinds of heat-resistant inorganic fibers whose heat-resistant temperatures are 500°C or more are molded in a mat shape or needle blankets formed by subjecting the integrated bodies to needling processing or both of the integrated bodies and the blankets, which has a surface treatment layer constituted of an inorganic binder and a filler, where a bulk density is 250-600 kg/m3 and preferably, hardness of a surface part measured by a type C-durometer in conformity with JIS K7312 is 45 or more.SELECTED DRAWING: None

Description

The present invention relates to a high temperature dust collecting ceramic filter element for collecting exhaust gas containing soot and having a temperature range from room temperature to high temperature.

The high-temperature exhaust gas emitted from sewage sludge incinerators and industrial furnaces contains soot dust composed of particulate matter such as soot and unburned matter. Therefore, a high-temperature dust collecting ceramic filter element (hereinafter, also referred to as a filter element) for removing soot and dust is installed in the filtration dust collector for treating the high-temperature exhaust gas. Various types of the shape of this filter element have been proposed, for example, a flat shape, a curved surface shape, a shape folded in a zigzag shape to widen the filtration area, a cylindrical shape with both ends open, or a cylindrical shape with one end open. A so-called candle type with a bottomed cylinder in which the other end is sealed has been proposed.

The above filter element is required to exhibit desired dust removal performance with as little pressure loss as possible, and is also required to have heat resistance of about 500 ° C. or higher because it is continuously exposed to high-temperature exhaust gas. In addition, since the required specifications may differ depending on the scale and method of the filtration dust collector, the type and particle size of soot, a high degree of freedom in design is possible so that various dust removal performances and upper limits of pressure loss can be flexibly dealt with. It is preferable to have. Further, it is desirable that the product is lightweight and has high strength so that it can be easily handled, and that it can be used for a long period of time without clogging, that is, it has a long life.

A high-temperature dust collecting ceramic filter element that removes dust by allowing high-temperature exhaust gas to permeate from the primary side (also referred to as the hot surface side or the dust collecting surface side) to the secondary side (also referred to as the cold surface side) is usually cold. By pulling a blower or the like from the surface side to suck the exhaust gas, soot dust is collected on the dust collecting surface side. Therefore, soot and dust accumulate on the dust collecting surface side with the passage of time, and after a certain period of time, the pressure loss becomes too large and the dust removing performance deteriorates. Therefore, by periodically introducing pulse air (high-pressure air for cleaning) from the cold surface side, air is flowed through the filter element in the direction opposite to the normal direction (that is, the direction from the secondary side to the primary side). So-called backwashing is generally performed to remove soot and dust accumulated on the dust collecting surface side.

Since the pressure loss is almost restored by the above-mentioned backwashing, the dust removal performance can be recovered to some extent. However, during long-term use, clogging may occur to the extent that it is difficult to recover by the above-mentioned backwash, and the pressure loss may gradually increase accordingly. In this case, it is common practice to replace the filter with a new one when the pressure loss becomes too high and the exhaust gas cannot be sucked by the blower on the suction side, for example. Therefore, it is desirable that the filter element is one in which the above-mentioned clogging is less likely to occur.

Further, it is desired that the new filter element used for the above replacement has a strength that is not damaged by handling during transportation or installation. Furthermore, in recent years, there has been a tendency to reduce the size of filtration dust collectors, and in the case of candle-type filters, the length in the axial direction can be increased or the distance between adjacent filters can be reduced accordingly. It has been. As a result, these adjacent filters are likely to come into contact with each other due to shaking such as an earthquake, and even in that case, strength and structure that are not easily damaged are required.

As a method for manufacturing the above-mentioned candle-shaped or cylindrical filter element, for example, a wet molding method as disclosed in Patent Document 1 and an injection molding method as disclosed in Patent Document 2 are known. .. The wet molding method is a method for producing a molded product having a predetermined shape by dehydration molding a slurry obtained by mixing inorganic fibers, an inorganic binder, and water in a predetermined blending ratio. Is a method for molding a molded product by injecting a slurry containing an inorganic fiber prepared in the same manner as described above.

However, since the conventional ceramic filter is insufficient in strength and easily damaged, as disclosed in Patent Document 3, by attaching a protective mounting member to the ceramic filter, the operation can be continued to some extent even if the ceramic filter is damaged. The technology to do is proposed. Although it is possible to reinforce the ceramic filter by providing the protective mounting member in this way, it takes time and cost to attach the member, so the ceramic filter itself does not use the protective mounting member as described above. It is preferable to increase the strength of the ceramic or to have a structure that does not break even if it is deformed to some extent when stress is applied by pressurization or the like.

As a technique for increasing the strength of the ceramic filter itself, Patent Document 4 describes mullite long fibers in a ceramic filter composed of a base material made of ceramic fibers and a filter layer formed on the surface thereof. A method of forming a base material by impregnating and firing alumina sol and silica sol after weaving by a filament winding method using the ceramic filter element is disclosed, whereby a ceramic filter element bonded and solidified by a bonding portion mainly composed of mullite is disclosed. It is stated that a substrate is obtained.

Further, Patent Document 5 proposes a technique for producing a flat fibrous molded product by impregnating a binder such as silica sol with laminated blanket-shaped ceramic fibers and then drying the laminated blanket-shaped ceramic fibers. Compared to wet molded products, this fibrous molded product has a smaller bulk specific gravity and is lighter in weight, has excellent flexibility due to the large amount of fiber entanglement, and has an appropriate hardness on the surface due to the binder, so it hits an object in the furnace. However, it is stated that it is not easily damaged and has excellent thermal shock resistance. Further, Patent Document 6 proposes a molded product in which a ceramic fiber blanket is coated with silica sol or the like as an inorganic adhesive, wound and laminated on a roll surface, and thereby formed into a cylindrical shape.

Japanese Unexamined Patent Publication No. 2002-045627 Special Table 2005-523154 Japanese Unexamined Patent Publication No. 2018-015682 Japanese Unexamined Patent Publication No. 2001-046818 Japanese Unexamined Patent Publication No. 3-257079 Japanese Unexamined Patent Publication No. 53-081518

However, in the above-mentioned molding method by wet molding or injection molding, it is necessary to defibrate in order to uniformly disperse the fibers. In this defibration, the fibers are broken and the fiber length is shortened, so that the entanglement of the fibers is reduced and the strength may be insufficient. As a countermeasure, there are countermeasures such as increasing the blending ratio of fibers and increasing the blending ratio of inorganic particles and inorganic binders, which makes it possible to improve the strength. There was a problem that the rate became small. On the contrary, if the required dust removal performance and pressure loss are prioritized, the durability test and the seismic test may be damaged due to insufficient strength.

Further, in the technique of Patent Document 4, the pressure loss becomes too large, and the desired dust removing performance and pressure loss conditions may not be satisfied in a short period of time. Further, since the techniques of Patent Documents 5 and 6 use heat insulating materials, the surface hardness, strength and heat impact resistance are prioritized, and therefore, the pressure loss becomes high as the use of the high temperature dust collecting ceramic filter element. It is considered too unsuitable.

As described above, the ceramic filter element is required to have a strength and a structure that do not easily break due to repeated thermal stress, vibration, or the like. The present invention has been made in view of such circumstances, has thermal shock resistance in a temperature range from room temperature to high temperature, is excellent in handleability during transportation and installation, and withstands vibration during operation and shaking of an earthquake. It is an object of the present invention to provide a ceramic filter element for high temperature dust collection which has strength and structure and has a degree of freedom in design that can change dust removal performance and pressure loss according to various specifications.

Among the various requirements described above, the present inventor desires that the ceramic fibers should be entangled with each other in order to realize a low pressure loss without being easily broken by repeated thermal stress or vibration. After careful research, we found that a mat-like aggregate with many fibers entangled with each other or a needle blanket obtained by needling this was used as the base material for the filter element for high-temperature dust collection that meets the above requirements. They have found that a ceramic filter element can be obtained, and have completed the present invention.

That is, the high-temperature dust collecting ceramic filter element according to the present invention is based on an aggregate obtained by molding one or more heat-resistant inorganic fibers into a mat shape, a needle blanket obtained by needling the aggregate, or both of them. The ceramic filter element used as the above is characterized by having a surface treatment layer composed of an inorganic binder and a filler, and having a bulk density of 250 to 600 kg / m ^3.

According to the present invention, it has thermal shock resistance in a temperature range from room temperature to a high temperature of about 1000 ° C., has excellent handleability during transportation and installation, has strength against shaking during operation and earthquake, and removes dust. It is possible to provide a high temperature dust collecting ceramic filter element having a degree of freedom in design that can change the performance and pressure loss to some extent.

It is a perspective view of the flat plate shape (a) and the curved plate shape (b) which are concrete examples of the shape of the filter element for high temperature dust collection which concerns on embodiment of this invention. It is a perspective view of the zigzag shape which is another specific example of the shape of the filter element for high temperature dust collection which concerns on embodiment of this invention. It is a perspective view of the cylindrical type (a) and the square tube type (b) which is still another specific example of the filter element for high temperature dust collection which concerns on embodiment of this invention. It is a candle-shaped perspective view (a) and the vertical sectional view (b) which are still another specific example of the filter element for high temperature dust collection which concerns on embodiment of this invention.

Hereinafter, embodiments of the high temperature dust collecting ceramic filter element according to the present invention will be described in detail. The high-temperature dust collecting ceramic filter element according to the embodiment of the present invention is an aggregate (hereinafter, also referred to as a mat-like aggregate) obtained by molding one or more heat-resistant inorganic fibers into a mat shape on the base material thereof, or the mat. Needle blankets obtained by needling the state aggregate, or both of them are used. The heat-resistant inorganic fiber is an inorganic fiber having a heat-resistant temperature of 500 ° C. or higher and 1600 ° C. or lower. Sex fibers and the like can be mentioned. The heat-resistant temperature T ° C. is sometimes referred to as the maximum operating temperature T ° C., and refers to a case where the heating line shrinkage rate when heated at an ambient temperature T ° C. for 24 hours is 4.0% or less.

The heat-resistant inorganic fiber preferably has an average fiber diameter of 2 to 15 μm, and more preferably 4 to 10 μm. If the average fiber diameter is less than 2 μm, the pressure loss of the finally molded filter element may become too large. On the contrary, if the average fiber diameter exceeds 15 μm, the toughness is likely to be impaired, so that the final molding is performed. There is a risk that the thermal shock resistance of the filter element will deteriorate. Further, the heat-resistant inorganic fiber preferably has an average fiber length of 1000 μm or more, and more preferably 3000 μm or more. Further, the heat-resistant inorganic fiber preferably has a bulk density of 30 to 160 kg / m ³ , more preferably 80 to 130 kg / m ^3.

The average fiber length is a straight line from one end to the other in the longitudinal direction of any 100 fibers on the obtained image obtained by photographing the group of fibers to be measured with an electron microscope. The distances are measured and calculated by arithmetically averaging them. On the other hand, the above average fiber diameter means that a group of fibers to be measured is photographed with an electron microscope, and the width of any part of any 200 fibers on the obtained image is measured. It is calculated by arithmetically averaging them.

As the filter element of the embodiment of the present invention, an aggregate obtained by molding the above-mentioned heat-resistant inorganic fiber into a mat shape may be used as the base material thereof, or a so-called needle blanket obtained by needling the mat-like aggregate. May be used, or one or more layers of matte aggregates and one or more layers of needle blankets may be laminated and used. The needling treatment involves repeatedly driving a plurality of needle-shaped bodies of a needle punching machine into a mat-shaped aggregate made of inorganic fibers from at least one surface (treated surface) to entangle the fibers. This is the so-called needle stick process.

^{In the above-mentioned needling process, the number of impacts per cm 2 of the} processed surface on which the needle-shaped body defined as the needling density is impacted is preferably 5 to 200 strokes, more preferably 10 to 100 strokes. preferable. If the needle ring density is ^{less than 5 strokes / cm 2} , the uniformity of the thickness of the base material made of the needle blanket will decrease, and the filtration thickness when finally molded into the form of the filter element may become non-uniform. is there. On the contrary, if the needling density exceeds 200 strokes / cm ² , problems such as breakage of the heat-resistant inorganic fiber and difficulty in processing the base material into a shape having a small curvature may occur.

The above mat-like aggregates include, for example, Arsen (registered trademark) manufactured by Denka Co., Ltd. for alumina fibers, Fibermax (registered trademark) manufactured by ITM Co., Ltd. for Murite fibers, and Nippon Glass Fiber Industry Co., Ltd. for glass fibers. MNA (trade name), MSS (trade name) manufactured by Nippon Glass Fiber Industry Co., Ltd. for silica fiber, Isowool (trade name) manufactured by Isolite Industry Co., Ltd. for silica / alumina fiber, silica, magnesia, calcia fiber, etc. As the biosoluble fiber, Isowool BSSR1300 (trade name) manufactured by Isolite Industry Co., Ltd. can be preferably used.

On the other hand, commercially available needle blankets may also be used. For example, Arsen (registered trademark) manufactured by Denka Co., Ltd. for alumina fibers, Fibermax (registered trademark) manufactured by ITM Co., Ltd. for Murite fibers, and glass fiber. MNA (trade name) manufactured by Nippon Glass Fiber Industry Co., Ltd., MSS (trade name) manufactured by Nippon Glass Fiber Industry Co., Ltd. for silica fiber, Isowool (trade name) manufactured by Isolite Industry Co., Ltd. for silica / alumina fiber, silica -As the biosoluble fiber such as magnesia-calcia fiber, Isoool BSSR1300 (trade name) manufactured by Isolite Industry Co., Ltd. can be preferably used.

The mat-like aggregate or needle blanket as the base material has a surface treatment layer composed of an inorganic binder and a filler formed on the surface portion on the primary side when used as a filter element. The blending ratio of these inorganic binders and fillers constituting the surface treatment layer is preferably in the range of 70:30 to 90:10 on a mass basis. As the above-mentioned inorganic binder, it is preferable to use a silica sol, an alumina sol, a zirconia sol, or a mixture of two or more thereof. On the other hand, the filler is filled with a needling-treated aggregate made of the above-mentioned heat-resistant inorganic fibers, which can partially fill the voids between the fibers on the surface portion to obtain an appropriate pore diameter. The material is used.

Specifically, as such a filler, inorganic particles having a median diameter D50 of 2 to 10 μm composed of at least one of alumina and mullite and a heat resistant temperature of 500 that can be used as a material for the above-mentioned aggregate are 500. It is preferable to use heat-resistant inorganic fibers of ° C. or higher and 1600 ° C. or lower, that is, one or more of the group consisting of alumina fibers, mullite fibers, silica-alumina fibers, silica fibers, glass fibers, and biosoluble fibers. .. The blending ratio of these inorganic particles constituting the filler and the heat-resistant inorganic fiber is preferably in the range of 70:30 to 90:10 on a mass basis. If the median diameter D50 of the inorganic particles used as the filler is less than 2 μm, the pore diameter formed when the voids between the fibers are filled becomes too small, and the pressure loss becomes large when used as a filter element, which is not preferable. On the contrary, when the median diameter D50 of the inorganic particles is larger than 10 μm, the ratio of the excessive pore diameter exceeding the pore diameter of an appropriate size increases, which is not preferable. The median diameter D50 means a particle size at an integrated value of 50% in a volume-based particle size distribution obtained by a laser diffraction type particle size distribution measuring device.

By surface-treating the needling-treated laminate using the inorganic binder and the filler in this way, a partially dense layer is formed, so that properties such as high strength and improved corrosion resistance can be obtained. It becomes possible to form an appropriate pore diameter. For example, needle blankets have a wide range of pore diameters of about 50 to 800 μm, but by surface-treating with an inorganic binder and filler as described above, an appropriate pore diameter of about 50 to 100 μm can be obtained. It becomes possible to form. In this case, it is not easy to adjust the pore size to an appropriate level using only the inorganic binder and the inorganic particles. The above-mentioned pore diameter was measured by "JIS R1665 fine ceramics pore diameter distribution test method for molded body by mercury press-fitting method".

As a method for forming the surface treatment layer, for example, a method may be used in which the needle blanket is formed into a predetermined shape and then impregnated with a slurry prepared by adding water to a mixture of the inorganic binder and the filler. The needle blanket is first impregnated with a slurry prepared by adding water to the inorganic binder to form a predetermined shape, dried, and then water is added to the mixture of the inorganic binder and the filler again to prepare the needle blanket. The method of impregnating the slurry may also be used.

The method of impregnation is not particularly limited, and the surface portion on the primary side may be coated with a brush or the like, or the surface portion may be coated with a spray or the like to prepare the slurry. The surface portion may be immersed in the container. At that time, the solid content concentration of the slurry containing the above-mentioned inorganic binder and filler realizes various characteristics such as desired bulk density, thickness, hardness, bending strength, and thermal shock resistance of the filter element to be finally produced. Generally, 20 to 50% by mass is preferable in order to obtain a predetermined impregnation amount or a predetermined solid content remaining after the slurry is dried. If the solid content concentration of this slurry is less than 20% by mass, it may be difficult to obtain the desired impregnation amount, and conversely, if it exceeds 50% by mass, the viscosity becomes too high and it becomes difficult to impregnate, resulting in uneven impregnation. , The above physical properties may deteriorate.

After impregnating the above slurry, it is dried from the surface side that becomes the primary side when used as a filter element, that is, the surface side on which high-temperature exhaust gas flows. As a result, when used as a high-temperature dust collection filter element, a surface treatment layer (coating layer) is formed on the primary side where high-temperature exhaust gas containing soot and dust comes into contact. Generally, the above drying is preferably carried out under a drying condition in which the ambient temperature is 90 to 130 ° C. for about 5 to 10 hours. If the above temperature is less than 90 ° C, it may not be sufficiently dried. On the contrary, if it exceeds 130 ° C, rapid evaporation of water occurs on the surface layer of the base material, and the generated vapor is transferred to the surface side. As a result, the solid content may be concentrated near the surface, causing uneven impregnation in the thickness direction. Further, if the drying time is less than 5 hours, it may not be sufficiently dried, and conversely, if it exceeds 10 hours, the effect obtained by drying is almost the same, which is uneconomical.

After the above drying treatment, the base material is fired if necessary before installation in the filtration dust collector. As the firing conditions at that time, it is preferable to hold the air temperature at an atmospheric temperature of 500 to 1000 ° C. for 0.3 hours or more, and more preferably 0.5 hours or more. Instead of the firing treatment before installation in the filtration dust collector, the base material may be fired with high-temperature exhaust gas at the start of operation immediately after installation in the filtration dust collector. The strength of the inorganic binder is expressed by the firing treatment as described above. The thickness of the surface treatment layer is preferably about 0.4 to 1.0 mm, and the amount of the slurry required per ^{1 cm 2 of the surface on the primary side can be obtained from this thickness.}

The shape of the filter element can be formed into various shapes according to the filtration dust collector, for example, (a) flat plate shape or (b) curved plate shape as shown in FIG. In order to make it wider, it should be folded into a zigzag shape as shown in FIG. 2, and further formed into a (a) cylindrical shape, a (b) square cylinder shape as shown in FIG. 3, and a candle shape as shown in FIG. Can be done. Although FIGS. 1 to 4 show an example in which the surface treatment layer S is formed on the surface of the filter element F on the primary side, the surface on which the surface treatment layer S is formed is shown in FIGS. It may be formed on the surface opposite to the surface shown in 4. For example, in FIG. 3A, the surface treatment layer S is provided on the outer peripheral side of the cylindrical filter element, but the present invention is not limited to this, and the surface treatment layer may be provided on the inner peripheral side. In this case, the inner peripheral side becomes the primary side, and the exhaust gas having a lower temperature permeates from the inside to the outside of the cylindrical filter element.

By the above firing treatment, a filter element having a bulk density of 250 to 600 kg / m ³ , which is less likely to break due to a three-point bending test, a hardness of 45 or more by a type C durometer, and a pressure loss of 100 to 500 Pa can be produced. The above pressure loss value has almost the same pressure loss value as that of the filter element manufactured by the conventional wet molding, and almost the same dust removal performance can be realized. In addition, with the above bulk density and hardness, it has excellent heat and shock resistance even when used in a high temperature range of about 1000 ° C from room temperature, and it has excellent handleability during transportation and installation, and it is resistant to vibrations and earthquakes during operation. It can be prevented from being easily damaged in the assumed seismic test.

The bulk density, pressure loss, etc. of the high-temperature dust collecting filter element according to the embodiment of the present invention are determined in consideration of the usage environment of the filter element, the type of dust, the desired dust removal performance, the value of pressure loss, and the like. It can be adjusted by appropriately changing the press pressure when compressing to form a molded body, the selection of the type of inorganic binder such as alumina sol and silica sol, the impregnation amount thereof, the number of impregnation times, and the like. Specifically, when it is desired to increase the bulk density, the press pressure at the time of forming the molded product may be increased, when it is desired to improve the bending characteristics, the needling density may be increased, and when it is desired to increase the hardness, the impregnation amount or impregnation may be increased. The thickness of the surface treatment layer may be increased by increasing the number of times, and when it is desired to reduce the pressure loss, it is sufficient to contain a large amount of heat-resistant inorganic fibers having a larger average fiber diameter, and it is desired to reduce the size of the pore diameter. In some cases, the mixing ratio of the inorganic particles constituting the filler may be increased.

High-temperature dust collection filter elements of Examples and Comparative Examples shown below were prepared using various heat-resistant inorganic fibers, and for each of them, bulk density, bending characteristics, hardness, thermal shock resistance, pressure loss, and dust removal The performance and the durability of dust removal were evaluated. The evaluation of these characteristics was carried out based on the following method.

(Bulk density)
It was obtained by measuring the dimensions of the high-temperature dust collection filter element and dividing its mass by the calculated volume. Those having a bulk density in ^{the range of 250 to 600 kg / m 3} were evaluated as "good".

(Bending characteristics)
The high-temperature dust collection filter element was processed into a length of 150 mm, a width of 50 mm, and a thickness of 25 mm, and was obtained by a three-point bending test by loading the center when supported by a span of 100 mm. Those that did not break by this method were evaluated as "good".

(hardness)
The hardness of the primary side of the high temperature dust collection filter element was measured by a type C durometer in accordance with JIS K7312, and those of 45 or more were evaluated as "good". The durometer refers to the force of a spring urging in the protruding direction of the push needle protruding from the pressure surface of the instrument by bringing the pressure surface of the instrument into contact with the surface of the object to be measured and the elastic force of the object to be measured. It is an instrument that measures hardness by balancing and reading the scale in the range of 0-100 indicated by the pointer at that time.

(Heat-resistant impact resistance)
The high-temperature dust collecting filter element is placed in a heating furnace heated to an atmospheric temperature of 1000 ° C. and held for 15 minutes, then taken out and naturally cooled in a room temperature air atmosphere for 15 minutes, and then charged again in the heating furnace under the same conditions. After holding for 15 minutes, it was taken out and naturally cooled in a room temperature air atmosphere for 15 minutes. The change in appearance when the heating and cooling cycles were repeated for a total of 10 cycles was visually observed, and the thermal shock resistance was evaluated as "good" when there was no damage.

(Pressure loss)
While flowing air at room temperature through a high-temperature dust collecting filter element at a filtration rate of 1 m / min, the pressure difference between the pressure on the primary side and the pressure on the secondary side was measured using a static pressure pitot tube. Those having this pressure difference of 100 to 500 Pa were evaluated as "good".

(Dust removal performance)
The high-temperature dust collection filter element is attached to the filtration dust collector, air at room temperature is flowed through the high-temperature dust collection filter element at a filtration rate of 1 m / min, and backwash air with a pressure of 0.25 MPa is blown in at intervals of 10 seconds (valve opening time 0. It was set to 5 seconds) and operated for 6 hours. At that time, 5 g of test dust was added every hour. After 6 hours, those obtained by dividing the mass of the collected dust by the total mass of the supplied dust and obtained by dividing it by 95% or more were evaluated as "good".

(Durability of dust removal)
When the value of the pressure loss at the start of measurement in the above dust removal performance test is P ₀ and the value of the pressure loss after 6 hours is P ₁ , _{the value of P 0} / P ₁ of 0.6 or more is “good”. I evaluated it.

[Example 1]
Nissan has a needle blanket (BSSR) ^{with a bulk density of 100 kg / m 3} and a thickness of 12.5 mm manufactured by Isolite Industries, Ltd., which is made of silica, magnesia, and calcia-based biosoluble fibers as heat-resistant inorganic fibers. A spray method in which a silica sol slurry (Snowtex 40) having a solid content concentration of 40% by mass manufactured by Chemical Industries, Ltd. is used as a filter element so that a layer of a curing agent having a thickness of 0.4 mm is formed on the primary side. Impregnated with.

The needle blanket impregnated above was layered in two layers and evenly compressed to a thickness of 20 mm to form a flat plate. After drying this molded product at an atmospheric temperature of 105 ° C. for 8 hours, alumina particles (median diameter D50 of 2 μm) and glass fibers (average fiber diameter of 10 μm) were prepared at a mixing ratio of 80:20 on a mass basis. When a slurry prepared by mixing 80 parts by mass of the above silica sol with 20 parts by mass of a filler composed of a mixture and further adding water to a solid content concentration of 10% by mass is used as a filter element, the thickness is 0. It was impregnated by the spray method so that a 6 mm surface treatment layer was formed. This was dried at an ambient temperature of 105 ° C. for 8 hours and then fired at an ambient temperature of 730 ° C. for 0.5 hours.

The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 45, and a pressure loss of 200 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good". Further, in order to confirm the presence or absence of long-term clogging that is difficult to remove by backwashing, the above-mentioned dust removal durability test time was extended from 6 hours to 2160 hours and measured in the same manner. As a result, when the value of the pressure loss before the test was P ₀ and the value of the pressure loss after the test was P ₂ , P ₀ / P ₂ was 0.5. Since P ₀ / P ₂ was 0.3 when the surface treatment layer was not formed, it can be seen that the formation of the surface treatment layer makes it difficult for long-term clogging to occur.

[Example 2]
The needle blanket impregnated in the same manner as in Example 1 was replaced with two layers to form four layers, and thereafter, as in Example 1, the needle blanket was compressed to a thickness of 20 mm, then a filler was applied, and drying and firing treatments were performed. It was. The obtained flat plate-shaped high-temperature dust collecting filter element had a bulk density of 600 kg / m ³ , bending characteristics of no breakage, a hardness of 70, and a pressure loss of 500 Pa, and all of these evaluations were "good". In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 95%, the dust removal durability was 0.6, and all of these evaluations were "good".

[Example 3]
A flat plate in the same manner as in Example 1 above, except that a needle blanket (Fibermax) having ^{a bulk density of 100 kg / m 3} and a thickness of 12.5 mm made of mullite fiber manufactured by ITM Co., Ltd. was used for the heat-resistant inorganic fiber. High temperature dust collection filter element was manufactured. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 180 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 4]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of alumina particles (median diameter D50 of 10 μm) and glass fibers (average fiber diameter of 10 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 100 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 5]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of mullite particles (median diameter D50 of 2 μm) and glass fibers (average fiber diameter of 10 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , bending characteristics of no breakage, a hardness of 65, and a pressure loss of 200 Pa, and all of these evaluations were "good". In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 6]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of mullite particles (median diameter D50 of 10 μm) and glass fibers (average fiber diameter of 10 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 100 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 7]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of alumina particles (median diameter D50 of 2 μm) and alumina fibers (average fiber diameter of 4 μm) was used as the filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 250 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 8]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of alumina particles (median diameter D50 of 10 μm) and alumina fibers (average fiber diameter of 4 μm) was used as the filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 150 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 9]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of mullite particles (median diameter D50 of 2 μm) and alumina fibers (average fiber diameter of 4 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 250 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 10]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of mullite particles (median diameter D50 of 10 μm) and alumina fibers (average fiber diameter of 4 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 150 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 11]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of alumina particles (median diameter D50 of 2 μm) and mullite fibers (average fiber diameter of 4 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 250 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 12]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of alumina particles (median diameter D50 of 10 μm) and mullite fibers (average fiber diameter of 4 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 150 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 13]
A flat plate-shaped high-temperature dust collection filter element was produced in the same manner as in Example 1 above, except that a mixture of mullite particles (median diameter D50 of 2 μm) and mullite fibers (average fiber diameter of 4 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 250 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 14]
A flat plate-shaped high-temperature dust collection filter element was produced in the same manner as in Example 1 above, except that a mixture of mullite particles (median diameter D50 of 10 μm) and mullite fibers (average fiber diameter of 4 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 150 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 15]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of alumina particles (median diameter D50 of 2 μm) and silica-alumina fibers (average fiber diameter of 3 μm) was used as the filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 250 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 16]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of alumina particles (median diameter D50 of 10 μm) and silica-alumina fibers (average fiber diameter of 3 μm) was used as the filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 150 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 17]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of mullite particles (median diameter D50 of 2 μm) and silica-alumina fibers (average fiber diameter of 3 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 250 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 18]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of mullite particles (median diameter D50 of 10 μm) and silica-alumina fibers (average fiber diameter of 3 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 150 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 19]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of alumina particles (median diameter D50 of 2 μm) and silica fibers (average fiber diameter of 4 μm) was used as the filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 250 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 20]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of alumina particles (median diameter D50 of 10 μm) and silica fibers (average fiber diameter of 4 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 150 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 21]
A flat plate-shaped high-temperature dust collection filter element was produced in the same manner as in Example 1 above, except that a mixture of mullite particles (median diameter D50 of 2 μm) and silica fibers (average fiber diameter of 4 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 250 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 22]
A flat plate-shaped high-temperature dust collection filter element was produced in the same manner as in Example 1 above, except that a mixture of mullite particles (median diameter D50 of 10 μm) and silica fibers (average fiber diameter of 4 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 150 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 23]
A flat plate-shaped high-temperature precipitator similar to Example 1 above, except that a mixture of alumina particles (median diameter D50 is 2 μm) and silica-magnesia-calcia-based biosoluble fibers (average fiber diameter 4 μm) is used as a filler. A dust filter element was manufactured. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 250 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 24]
A flat plate-shaped high-temperature precipitator similar to Example 1 above except that a mixture of alumina particles (median diameter D50 is 10 μm) and silica-magnesia-calcia-based biosoluble fibers (average fiber diameter 4 μm) is used as a filler. A dust filter element was manufactured. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 150 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 25]
A flat plate-shaped high-temperature collection in the same manner as in Example 1 above, except that a mixture of mullite particles (median diameter D50 is 2 μm) and silica-magnesia-calcia-based biosoluble fibers (average fiber diameter 4 μm) is used as a filler. A dust filter element was manufactured. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 250 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 26]
A flat plate-shaped high-temperature collection in the same manner as in Example 1 above, except that a mixture of mullite particles (median diameter D50 is 10 μm) and silica-magnesia-calcia-based biosoluble fibers (average fiber diameter 4 μm) is used as a filler. A dust filter element was manufactured. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 150 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, the dust removal durability was 0.7, and all of these evaluations were "good".

[Example 27]
A mat-like aggregate manufactured by ISOLITE INSULA Co., Ltd. was prepared in place of the needle blanket, and a silica sol slurry was placed on the mat-like aggregate in the same manner as in Example 1 to form a layer of a curing agent having a thickness of 0.4 mm on the primary side. Was impregnated so that This was layered in two layers, compressed evenly to a thickness of 20 mm, molded into a flat plate, and dried at an atmospheric temperature of 105 ° C. for 8 hours.

After that, in the same manner as in Example 1, a surface treatment layer having a thickness of 0.6 mm is formed on the primary side of a slurry of silica sol of 80 parts by mass with respect to 20 parts by mass of a filler composed of a mixture of alumina particles and glass fibers. A flat plate-shaped high-temperature dust collecting filter element was produced by impregnating, drying and firing. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 60, and a pressure loss of 100 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, and the dust removal durability was 0.8, and all of these evaluations were "good".

[Example 28]
The impregnated needle blanket produced in the same manner as in Example 1 and the impregnated mat-like aggregate produced in the same manner as in Example 27 are stacked one layer at a time in this order so as to have a thickness of 20 mm. It was compressed evenly so as to be, and formed into a flat plate.

After that, in the same manner as in Example 1, a surface treatment layer having a thickness of 0.6 mm is formed on the primary side of a slurry of silica sol of 80 parts by mass with respect to 20 parts by mass of a filler composed of a mixture of alumina particles and glass fibers. A flat plate-shaped high-temperature dust collecting filter element was produced by impregnating, drying and firing. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, a hardness of 65, and a pressure loss of 110 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, and the dust removal durability was 0.7, and all of these evaluations were "good".

[Comparative Example 1]
Bulk (Fibermax) manufactured by ITM Co., Ltd., which is made of mullite fiber, was used as a heat-resistant inorganic fiber, and a silica sol as an inorganic binder, an organic binder, and water were mixed thereto to prepare a slurry. The obtained slurry was wet-molded using a molding die having an outer diameter of 90 mm to obtain a candle-shaped molded body having a wall thickness of 20 mm. This molded product was dried from the surface side at an atmospheric temperature of 105 ° C. for 8 hours, and then fired at an atmospheric temperature of 730 ° C. for 0.5 hours.

The resulting high temperature dust collecting filter element candle, with bulk density 250 kg / m ^3, a pressure drop 500 Pa, thermal shock resistance are intact even after 10 cycles, dust removal performance is 97%, the durability of the dust The property was 0.6 and the hardness was 50, and all of these characteristics were evaluated as "good". However, fracture occurred due to the bending characteristics.

[Comparative Example 2]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of alumina particles (median diameter D50 of 12 μm) and glass fibers (average fiber diameter of 10 μm) was used as a filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a hardness of 65, and a pressure loss of 100 Pa, and all of these evaluations were “good”. In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, and these evaluations were also "good". However, the durability of dust removal was 0.5, which did not meet the evaluation criteria.

[Comparative Example 3]
A flat plate-shaped high-temperature dust collecting filter element was produced in the same manner as in Example 1 above, except that a mixture of alumina particles (median diameter D50 of 1 μm) and glass fibers (average fiber diameter of 10 μm) was used as the filler. The obtained high-temperature dust collection filter element had a bulk density of 250 kg / m ³ , a bending characteristic of no breakage, and a hardness of 65, and all of these evaluations were "good". In addition, the thermal shock resistance was not damaged even after 10 cycles, the dust removal performance was 99%, and all of these evaluations were "good". However, the pressure loss was 520 Pa and the dust removal durability was 0.4, which did not meet the evaluation criteria.

F Ceramic filter element S Surface treatment layer

Claims (7)

An aggregate obtained by molding one or more heat-resistant inorganic fibers into a mat shape, a needle blanket obtained by needling the aggregate, or a ceramic filter element using both of them as a base material, which is an inorganic binder and a filler. A high-temperature dust collecting ceramic filter element having a surface-treated layer composed of and having a bulk density of 250 to 600 kg / m ^3. The high-temperature dust collecting ceramic filter element according to claim 1, wherein the surface-treated layer has a hardness of 45 or more measured by a type C durometer in accordance with JIS K7312. The heat-resistant inorganic fiber has a heat-resistant temperature of 500 ° C. or higher and 1600 ° C. or lower, and is one or more of the group consisting of alumina fibers, mullite fibers, silica-alumina fibers, silica fibers, glass fibers, and biosoluble fibers. The high temperature dust collecting ceramic filter element according to claim 1 or 2, wherein the high temperature dust collecting ceramic filter element is characterized by the above. The high-temperature dust collecting ceramic filter element according to any one of claims 1 to 3, wherein the inorganic binder is a silica sol, an alumina sol, a zirconia sol, or a mixture thereof. The filler is a group consisting of inorganic particles having a median diameter D50 of at least 2 to 10 μm and made of at least alumina or mullite, and a group consisting of alumina fibers, mullite fibers, silica-alumina fibers, silica fibers, glass fibers, and biosoluble fibers. The high-temperature dust collecting ceramic filter element according to any one of claims 1 to 4, which comprises one or more kinds of inorganic fibers. The ceramic filter element is characterized in that the needling-treated base material is formed into a flat plate shape, a curved plate shape, or a zigzag shape in a single layer or a plurality of layers. The high temperature dust collecting ceramic filter element according to any one of 5. In the ceramic filter element, the needling base material is formed in a single layer or multiple layers in the shape of a cylinder or a square cylinder, and both ends in the axial direction thereof are open or one end thereof is formed. The high-temperature dust collecting ceramic filter element according to any one of claims 1 to 5, wherein the high-temperature dust collecting ceramic filter element is sealed.

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