JPH06137128A - Ceramics filter and filter device - Google Patents

Abstract

PURPOSE:To provide a crossflow type ceramics filter of high durability and reliability for sealing and holding. CONSTITUTION:In a ceramics filter 1 in which filter elements 2 having a plurality of through-holes in a square plate body in parallel are laminated, and gas passages 5 nearly meeting at right angles with the through-holes are provided between the elements, the faces annularly worked so as to surround both side faces on which the through-holes open and both side faces on which the other gas passages 5 formed between the elements 2 open, and having width over 8mm, are the sealing parts 8 of this filter device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic filter and a filter device suitable for a particulate trap for treating exhaust gas of a diesel engine.

[0002]

2. Description of the Related Art As a filter for a particulate trap for treating exhaust gas of a diesel engine, a honeycomb type ceramics filter having a dust-containing gas passage and a clean gas passage all parallel to each other, and a dust-containing gas passage parallel to each other are provided. There is a cross-flow ceramic filter in which clean gas passages that are parallel to each other are alternately formed so as to be substantially orthogonal to each other. In the cross-flow ceramic filter, the outer shape of the passage is a rectangular parallelepiped.

A honeycomb ceramic filter having a cylindrical shape or an elliptic cylindrical shape can be easily manufactured by an extrusion molding method. In the honeycomb ceramic filter, the rounded outer periphery can be sealed with a sealing material from the surroundings. In a particulate trap using a ceramics filter of the type B, a regeneration method in which particulates (particles containing carbon as a main component such as soot) are incinerated on the ceramics filter without backwashing has hitherto been mainly directed. Therefore, the gas pressure did not change significantly, and although the sealing method was important, the sealing conditions were not so severe.

However, in the particulate trap for performing backwash regeneration in which the cross flow type ceramics filter is incorporated, in addition to indirectly receiving the vibration from the diesel engine and the road surface, the differential pressure of the backwash gas for backwash regeneration is applied. Since it is repeatedly received, it has been found that a method of sealing or holding a durable ceramic filter is a particularly important technique that needs to be solved for its practical use.

As for the sealing material for ensuring the seal between the exhaust gas and the particulates and for holding the ceramics filter in the casing, various contrivances have been made up to now, and it is irreversible in JP-A-3-168313. A sealing material is used in which a ribbon-like sheet containing an inorganic thermally expansive substance (for example, vermiculite) that exhibits various thermal expansions and a ceramic fiber is wrapped with a cloth made of quartz glass fiber. It has been proposed to prevent the sealing material from scattering around by a quartz glass cloth that generates pressure and maintains flexibility without deterioration even at high temperatures, thereby ensuring the durability of the sealing material.

Regarding the ceramics filter,
To secure the strength of the seal part of the cross flow type ceramic filter so that sufficient sealing pressure can be given even if the weight is reduced and the thickness of the ceramic is reduced, ribs are bonded to the seal part that holds the ceramic filter. Figure 5 reinforced
The structure of the above is proposed in Japanese Patent Laid-Open No. 4-114710.

FIG. 5 is a perspective view showing an example of a conventional cross flow type ceramics filter. In the figure, 1 is a ceramics filter, 2 is a filter element, 3 is a through hole,
4 is a spacer (also serves as an adhesive), 5 is a gas passage, 8
Is a seal portion, and 15 is a rib.

[0008]

SUMMARY OF THE INVENTION The present invention is a cross-flow type ceramic filter which is more difficult to hold in a seal and its casing, and a ceramic filter which enables reliable sealing and holding, and this ceramic filter is incorporated. Another object of the present invention is to provide a filter device which is suitable for a particulate trap for diesel engines in which backwash regeneration is performed and which has excellent durability of the seal portion.

[0009]

The present invention has been made in order to achieve the above-mentioned object, and a ceramics filter according to the present invention comprises a rectangular plate-like body made of porous ceramics, from one end surface to the other. A plurality of filter elements having a plurality of mutually parallel through-holes penetrating to the end face are aligned with the end faces on both sides where the plurality of through-holes are open, and the edge of the boundary between the end faces where the plurality of through-holes are open A ceramic filter that is integrated so that another gas passage that is substantially orthogonal to the through hole is formed between each filter element with a spacer that extends along the plurality of filter elements. The surface of both sides of the ceramics filter with through holes opened, or the ceramics filter with another gas passage formed between the filter elements is opened. Rounded processed 8mm surrounding the surface of the side
The surface having the above width is used as a seal portion.

In the cross flow type ceramic filter, since the gas passages are formed so as to intersect each other at a right angle, making the outer shape of the ceramic filter into a cylindrical shape or an elliptical shape requires additional processing in manufacturing, and It was found that using a ceramic filter having a cylindrical shape or an elliptic shape would sacrifice the effective filtration area, but it would be useful as a means for ensuring the durability of the sealed portion.

In the ceramic filter of the present invention, since the rounded seal portion is rounded so as not to have at least a recess when it is traced in the circumferential direction, the sealing material is wrapped around the seal portion of the ceramic filter to surround it. When tightening with a metal band, etc., the sealing material is pressed against the sealing part of the ceramic filter over the entire length, and there is no place where excessive stress is applied to the sealing material,
The pressure applied to the seal material is equalized, enabling highly reliable sealing. The rounded portion of the seal portion is convex outward, and the radius of curvature thereof is preferably 40 mm or more.

In the ceramic filter of the present invention, the property that ceramics are generally strong against compressive stress and weak against tensile stress and shear stress is effectively utilized, and the direction of the stress at the portion to be tightened through the sealing material is set to the seal portion. By rounding it, the state is changed to a state closer to a simple compressive stress so that the sealing portion of the ceramic filter as a whole can withstand a higher sealing pressure.

If the sealing portion is rounded only at the portion to which the sealing material having a width of 8 mm or more is applied, the other portion is reliable even if the cross section is rectangular or has a recess. It has a feature that it can be sealed, and unlike the case of a conventional cross-flow ceramic filter having a rectangular parallelepiped shape, the sealing material is unlikely to fall off or scatter at the corners of the sealing material.

The portion where the seal portion is provided may be around the end surface where the exhaust gas containing particulates flows into the ceramic filter, or around the end surface where the filtered clean gas is discharged. However, in the case of a cross-flow ceramics filter, it is possible to obtain a higher tightening pressure of the sealing material because the area around the end surface where the exhaust gas containing particulates flows in is closer to the place where the spacer is located, and the through hole It is preferable because the seal portion can be formed without blocking the space. However, depending on the application and specifications of the ceramics filter, it may be preferable to set it around the end face from which the filtered clean gas is discharged.

The seal portion is rounded along the extending direction of the seal material (circumferential direction of the seal portion) so that there is no dent, but the presence of continuous ridges or grooves in the extending direction of the seal material results in good sealing performance. Is effective to prevent the sealing material from falling off. If the width of the seal part is 8 mm or more, a durable seal is possible, and the width of the seal part is 8 mm or more and 20 mm or less for the reason of manufacturing and processing and to secure a larger effective filtration area. Preferably.

In a preferred embodiment of the ceramics filter of the present invention, a ceramics filter having a plurality of through-holes in the filter element is opened on both sides of the ceramics filter or another gas passage formed between the filter elements is opened. A rib having a thickness of 8 mm or more is joined around the both sides of the filter, and a rounded surface having a width of 8 mm or more that surrounds both sides of the ceramic filter on the side where the rib is joined serves as a seal portion. Has been done.

If the structure is such that ribs are joined to the ceramic filter and the seal portion is formed into a round shape by mainly processing the rib portion, the wall of the ceramic filter that secures an effective filtration area is formed. A ceramics filter can be obtained with almost no scraping, and the machining allowance of the ceramics filter requiring processing can be reduced, so that the time and labor for processing can be reduced as a whole.

In another preferred embodiment of the ceramic filter of the present invention, the cross section of the seal part cut along a plane parallel to the end face adjacent to the seal part is circular or elliptical. In this case, the sealing pressure applied to the sealing portion of the ceramics filter can be made more uniform, and good exhaust gas and particulate sealing performance and reliability can be secured.

In another preferred embodiment of the ceramic filter of the present invention, the cross section of the seal portion cut along a plane parallel to the end face adjacent to the seal portion has a racetrack shape.
A race track is a track where athletics are played, and it has the shape of a straight line connecting two semicircles. When the ceramic filter has a rectangular cross section, the most difficult part to seal and the part where the sealing material is likely to scatter are the corners of the square. With the shape, since it is possible to eliminate a corner portion where sealing is difficult, it is possible to secure a durable seal which is the object of the present invention.

In addition, in the structure in which the cross section of the seal portion is racetrack-shaped, the plurality of ceramic filters are adjacent to each other (the seal material may be sandwiched therebetween so that the opening surfaces of the gas passages are the same surface). It is also possible to integrally seal and hold a plurality of ceramic filters by forming a rounded seal part around both end faces where side by side, through holes or gas passages are open. Is. In this case, it is possible to provide a bulge in the seal part of the ceramic filter arranged in the middle so that the cross-sectional shape of the entire seal part is elliptical, but this casing part is reinforced by reinforcing the casing side of the straight seal part. It is relatively easy to ensure a good seal if even pressure is applied.

The filter device of the present invention comprises a plurality of filter elements having a plurality of mutually parallel through holes penetrating from one end face to the other end face of a rectangular plate-like body made of porous ceramics. Aligning the end faces on both sides where the through holes are open, sandwiching a spacer extending along the edge of the boundary between the end faces where a plurality of through holes are open, and the through holes between the filter elements A ceramic filter integrated so as to form another gas passage that is substantially orthogonal to each other is formed on another surface formed on both sides of the ceramic filter in which a plurality of through holes of the filter element are opened or between the filter elements. A rounded surface having a width of 8 mm or more, which surrounds both sides of the ceramic filter having a gas passage opening, is used as a seal portion. Characterized by comprising retained and housed in a metal casing through a wound heat resistance of the sealing material in pole tip.

As the sealing material of the ceramics filter, the sealing material in which a ribbon-shaped sheet containing an irreversibly thermally expansive inorganic thermally expansive substance (for example, vermiculite) and a ceramic fiber is wrapped with a quartz glass cloth is used. Is preferable, after storing in a steel casing,
By preheating the entire seal part including the casing to a temperature at which the thermally expansive substance irreversibly thermally expands, a sufficient amount of sealing pressure can be generated, and the strength of the portion of the casing surrounding the sealing material is kept at a temperature. By designing to ensure even when the
It is possible to provide a filter device having a durable and reliable ceramic filter seal and holding performance.

The filter device incorporating the ceramics filter according to the present invention is suitable for a particulate trap in which backwash regeneration is performed for removing particulates in exhaust gas of a diesel engine, and vibration from the engine or the road surface is generated. Of course, it has sufficient reliability and durability even when a gas differential pressure due to backwashing is repeatedly applied.

[0024]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

FIG. 1 shows an example in which the ceramics filter according to the present invention is incorporated in a particulate trap.
It is a perspective view of the filter device with which the casing part was cut. FIG. 2 is a plan view showing a state in which the sealing material is wound around the ceramic filter. In both figures, 1 is a filter, 2 is a filter element, 3 is a through hole, 4 is a spacer, 5 is a gas passage, 6 is a sealing material, 7 is a casing, 8
Is a seal part, 9 is a backwash nozzle, 10 is an outlet pipe, 11 is a closing valve, 12 is a solenoid valve, 13 is a clean gas space, and 14 is a hopper.

In this example, the filter element 2 and the spacer 4 of the ceramics filter 1 are made of cordierite-type ceramics having a sufficient heat resistance for a particulate trap, a small coefficient of thermal expansion and a strong resistance to thermal shock. The porosity is 40% and the average pore diameter is 25 μm. The material of the ceramic filter 1 is
Depending on the application, β-spodumene, β-eucryptite, aluminum titanate, silicon carbide and the like can be used.

In this example, the through holes 3 penetrating the filter element 2 have an elliptical cross section, and the through holes 3 are formed in three rows in a staggered manner, but it may be better to have one row or two rows. Many. The three rows of through holes 3 are preferably used because the porous ceramic has a large porosity and an average pore diameter, and a fine filter layer having a filtering function is formed on the inner surface of the through holes 3. This is the case.

Each spacer 4 has a width of 20 mm and a thickness of 6 m.
m, a gas passage 5 having a width of about 6 mm is formed between the filter elements 2, and the filter element 2 and the spacer 4 are integrally joined via a ceramic adhesive (in this example, the spacer itself is bonded). After joining, the ceramic filter 1 having a diameter of 126 mm, a height of 259 mm, and an effective filtration area of 0.9 m ^{2 was formed into} a cylindrical shape. In this case, the seal portion 8 that can be used for the seal has a width of 20 mm, which is the same as the spacer 4, the cross section of the seal portion 8 is circular, and the width in which the seal portion 8 is in contact with the seal material 6 is 15 mm.

In this example, the through hole 3 of the filter element 2 serves as a passage for exhaust gas of a diesel engine (not shown) containing particulates, and a gas passage 5 having a width of about 6 mm formed between the filter elements 2. Is the passage for the filtered clean gas. The narrower the width of the gas passage 5 used as a passage for clean gas, the ceramic filter 1
However, it is preferable that the gas pressure of the backwash gas (in many cases, compressed air) injected from the backwash nozzle 9 immediately reaches every corner of the gas passage 5 and facilitates the rise of the differential pressure. The width is preferably about 3 to 10 mm.

As the sealing material 6, a ribbon-shaped sheet made of vermiculite, an inorganic fiber and a binder, which is said to have durability and reliability, and a quartz glass cloth is wound is used. The sealing material 6 is arranged between the sealing portion 8 and the casing 7 provided on both sides, and is preheated to about 400 ° C. to cause irreversible thermal expansion to hold the ceramics filter 1.

The exhaust gas of the diesel engine is introduced from the upper part of the casing 7, flows into the through hole 3 of the ceramic filter 1, is filtered on the surface of the through hole 3, enters the gas passage 5, and exits via the clean gas space 13. Sent to pipe 10. During this time, particulates in the exhaust gas are deposited on the inner surface of the through hole 3. If particulates are deposited on the inner surface of the through hole 3 for a certain period of time, the filtration pressure difference becomes large, so the ceramic filter 1 is backwashed and regenerated.

When backwashing is performed, the closing valve 11 is temporarily closed, the electromagnetic valve 12 is opened for a short time (for example, 0.1 seconds), and compressed air is jetted from the backwashing nozzle 9. The compressed air flows into the casing 7, is introduced into the ceramics filter 1 through the opening of the gas passage 5, the pressure in the clean gas side space 13 is momentarily increased, and the gas is trapped in the ceramics filter 1 during normal particulate collection. Flowing in the opposite direction to, the particulates deposited on the surface of the through hole 3 are separated. The separated particulates fall by gravity onto the hopper 14 below the casing 7.

Although not shown, the normal hopper 14
A particulate incineration unit is provided on the lower side, and the particulates collected in the particulate incineration unit are incinerated. In addition, a filter device having a configuration in which two sets of the same filter device are connected in parallel by pipes and exhaust gas can be continuously treated by alternately performing backwash regeneration of each filter device is used as a particulate trap. .

FIG. 3 is a perspective view showing another example of the ceramics filter of the present invention. The thickness of the ceramics filter 1 is 20 mm along the ridge of the surface where the through hole 3 is opened.
4 ribs 15 are joined in total, and a seal portion 8 having a width of 20 mm is formed so as to surround the surface where the through hole 3 is open. The seal portion 8 has a racetrack-shaped cross section. In this case, two of the filter elements 2 at the ends are slightly shaved by machining, but the other filter elements 2 are not shaved, have the same size and shape, and have a cutting allowance. It can be seen that the number is remarkably small as compared with the examples shown in FIGS.

FIG. 4 is a perspective view showing still another example of the ceramic filter of the present invention. In this example, the ceramic filter 1 having a thickness of 18 mm is formed along the ridge around the surface where the through hole 3 is opened. Since a total of eight ribs 15 are joined and the seal portion 8 is formed in a circular shape around the rib 15, it is not necessary to grind the wall of the ceramic filter, and the process of providing the seal portion 8 on the ceramic filter 1 is performed by the rib. You only have to do around 15.

Test Example Particulate trap (effective filtration area 1.
8m ² ) is connected to the exhaust pipe of a diesel engine with an output of 100 horsepower, the diesel engine is continuously operated at a load of 80%, and exhaust gas at about 300 ° C is introduced into the filter device at a flow rate of about 1000m ³ / hour. By alternately backwashing each ceramic filter 1 every 5 minutes,
The pressure difference of the filter was kept at 2000 mm or less.

During this period, the concentration of black smoke in the exhaust gas introduced into the filter device (which is almost the same as the concentration of particulates) was 0.13 g / as measured by the Baccaraca method.
It was m ³ , and the black smoke concentration at the position of the outlet pipe 10 was measured by the Bosch method, resulting in a level of 0.001 g / m ³ , and the black smoke collection efficiency was 99.2%. On the other hand, as a result of conducting a similar test with the particulate trap incorporating the conventional ceramics filter shown in FIG. 5, the same level of collection efficiency was obtained, but after a total of about 450 hours, the sealing material had a rectangular shape. While the corner portion of the seal portion 8 was damaged and the scattering of the seal material started, the efficiency of collecting black smoke began to decrease, whereas the filter device according to the present invention changed completely even after a total of about 1000 hours of use. Was not recognized.

[0038]

According to the cross-flow type ceramic filter of the present invention, there is no corner portion where sealing is difficult in the sealing portion of the ceramic filter, and a plurality of through-holes of the filter element are provided on both sides of the ceramic filter or the filter. Durability and reliability due to tightening because the rounded surface with a width of 8 mm or more that surrounds the both sides of the ceramic filter where another gas passage formed between the elements is open is the seal part It has become possible to seal and hold with.

The filter device incorporating this ceramics filter is capable of withstanding the fluctuation of the differential pressure of the sealing portion for a long time even if the backwashing regeneration of the ceramics filter is repeated as well as the vibration from the engine and the road surface. Since it is possible to realize a highly durable and reliable particulate trap, it is useful as an environmental measure for a diesel engine, which is said to have high energy efficiency, and its industrial utility value is great.

[Brief description of drawings]

FIG. 1 is a perspective view of a filter device in which a casing portion is cut, showing an example of a particulate trap incorporating a ceramics filter according to the present invention.

FIG. 2 is a plan view in which a sealing material is wound around the ceramic filter shown in FIG.

FIG. 3 is a perspective view showing another example of the ceramics filter of the present invention.

FIG. 4 is a perspective view showing another example of the ceramics filter of the present invention.

FIG. 5 is a perspective view showing an example of a conventional cross-flow ceramic filter.

[Explanation of symbols]

 1: Ceramics filter 2: Filter element 3: Through hole 4: Spacer (also serving as an adhesive) 5: Gas passage 6: Seal material 7: Casing 8: Seal part 9: Backwash nozzle 10: Outlet pipe 11: Stop valve 12: Solenoid valve 13: Clean gas space 14: Hopper 15: Rib

Claims (6)

[Claims] 1. A plurality of filter elements having a plurality of mutually parallel through holes penetrating from one end surface to the other end surface of a rectangular plate-shaped body made of porous ceramics, the plurality of through holes being opened. Aligning the end faces on both sides, sandwiching a spacer extending along the edge of the boundary between the end faces where a plurality of through holes are open, another through-hole between each filter element that is substantially orthogonal to the through hole is provided. A ceramic filter integrated so as to form a gas passage, in which a plurality of through holes of the filter element are opened, and another gas passage formed between the surfaces on both sides of the ceramic filter or between the filter elements is opened. A ceramic filter having a rounded surface having a width of 8 mm or more that surrounds both sides of the ceramic filter as a seal portion. 2. The surface of both sides of the ceramic filter having a plurality of through holes of the filter element opened, or both sides of the ceramic filter having another gas passage formed between the filter elements opened. A rib having a thickness of 8 mm or more is joined to the periphery of the face, and a rounded face having a width of 8 mm or more that surrounds both sides of the ceramic filter on the side where the rib is joined serves as a seal portion. Ceramic filter. 3. A ceramics filter according to claim 1, wherein the cross section of the seal part cut along a plane parallel to the end face adjacent to the seal part is circular or elliptical. 4. The ceramics filter according to claim 1, wherein the seal section cut along a plane parallel to the end surface adjacent to the seal section has a racetrack shape. 5. A plurality of through holes are formed in a plurality of filter elements having a plurality of mutually parallel through holes penetrating from one end surface to the other end surface of a rectangular plate-shaped body made of porous ceramics. Aligning the end faces on both sides, sandwiching a spacer extending along the edge of the boundary between the end faces where a plurality of through holes are open, another through-hole between each filter element that is substantially orthogonal to the through hole is provided. In the ceramic filter integrated so that the gas passage is formed, a plurality of through holes of the filter element are opened, and another gas passage formed between the surfaces on both sides of the ceramic filter or between the filter elements is opened. The heat-resistant surface of the ceramic filter, which has a width of 8 mm or more and which surrounds both sides of the ceramic filter, is a seal portion, and the ceramic filter is wound around the seal portion. Filter apparatus characterized by comprising retained and housed in through the sealing member in a metallic casing. 6. The filter device according to claim 5, wherein the filter device is for a particulate trap in which backwash regeneration is performed to remove particulates in exhaust gas of a diesel engine.