JP2002147218A - Device of removing particulate material in exhaust gas of diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove 100% of particulate materials (PM) by continuously sucking and removing the particulate materials, and incinerating the sucked materials in a device of removing particulate materials in exhaust gas for a diesel engine. SOLUTION: A honeycomb 1 is formed by winding in several turns or stacking so as to have the specified intervals (10-5000 μm) a plain plate and a corrugated plate, a pain plate and an irregular plate, a corrugated plate and another corrugated plate, each made from a heat resistant metal foil (thickness is about 20-100 μm), and the exhaust gas containing the particulate materials is passed through gaps of the honeycomb 1. Very fine particulate materials come in contact with the wall surface or collide against the wall surface of the honeycomb 1 during passing through the gaps, and are trapped. The trapped particulate materials are incinerated by heating the heat resistant metal foil constituting gaps or by heating the exhaust gas, and the honeycomb 1 is reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for removing particulate matter in exhaust gas discharged from a vehicle equipped with a diesel engine. More specifically, particulate matter (PM) consisting of carbon fine particles in exhaust gas emitted from diesel vehicles is removed by actively attaching to the inner wall surface of the metal honeycomb, and the removed particulate matter is completely heated by heating. The present invention relates to an apparatus for removing particulate matter (DPF) from diesel engine exhaust gas that can be incinerated.

[0002]

2. Description of the Related Art Conventionally, pollution caused by a large amount of particulate matter, that is, carbon fine particles emitted from so-called diesel vehicles such as trucks and buses has been regarded as a problem, and countermeasures have been taken. As a first representative example, as shown in FIG. 19, a coarse filter composed of a felt-like laminate in which ceramic fibers are irregularly laminated and a dense filter are laminated in two layers, and these are energized. There is a ceramic fiber filter that is held between a heatable wire mesh heater and a wire mesh holder, constrained, folded in the shape of a petal, processed into a cylindrical shape with a wide filtration area, and used as a filter.

In the first method, when particulate matter in exhaust gas is filtered by a filter, a predetermined clogging is detected by a sensor after depositing and depositing the particulate matter between fibers of the filter. This is incinerated to regenerate the filter.

That is, as shown in FIG. 20, a particulate matter (PM) of exhaust gas generated by a diesel engine is configured to be filtered and captured by a pair of filters A and B.
First, the particulate matter of the exhaust gas is filtered and captured by the filter A. Then, the particulate matter adheres and accumulates on the filter A and is clogged. When the ventilation resistance increases, the pressure sensor senses the change, and the filter C is switched to the filter B by the switching valve C, and the filtration and capture are continued. Filter A is regenerated by burning off particulate matter clogging the filter during that time. Similarly, the filter B is switched and regenerated when particulate matter is clogged in the filter, and this is repeated alternately. D in the figure is an exhaust pipe for introducing exhaust gas.

The exhaust gas particulate matter removing apparatus shown in FIG. 19 is provided with two switching type filters having a regeneration function shown in FIG. 20. If the pressure sensor or the controller breaks down, the filter becomes excessively clogged, and the exhaust pressure (pressure loss) becomes abnormally high due to the ventilation resistance, or the combustion temperature becomes too high.

Further, in the apparatus for removing particulate matter of a ceramic fiber filter shown in FIG. 19, the particulate matter adhered and deposited on the filter and clogged is restrained with the filter interposed therebetween, and the filter is connected to the filter by a heat-generating wire mesh 30. Electric heating together and incineration. In this electric heating, not only the two filters occupy a large volume as shown in FIG. 20, but also the electric energy consumed for this electric heating is insufficient for the batteries or generators normally provided in buses, trucks and the like. In order to achieve this, not only a high-performance generator but also a regulator for converting the generated power to 24 volts, a controller, and the like are required, and the system is complicated and large-sized and expensive. More decisively, as disclosed in JP-A-11-294140, when an abnormality occurs in the above-mentioned system and particulate matter is excessively captured and deposited on the filter, heat damage or the like may be caused during the regeneration of the filter. Part of the exhaust gas needs to escape to the atmosphere in order to avoid problems. That is, if this continues, there is a disadvantage that the particulate matter in the exhaust gas is dripped off.

FIG. 21 shows a second example of a so-called wall flow honeycomb, which is a porous ceramic honeycomb made of cordierite, silicon carbide, or the like, in which innumerable pores are provided in a wall through which exhaust gas passes. By using a filter E composed of a structure, the carbon particles are filtered and captured by the filter E, and the carbon particles adhered and deposited on the filter are incinerated, thereby eliminating clogging of the filter E and continuously used while regenerating. There is a filter regeneration type particulate matter removal device.

[0008] A filter E of the porous ceramic honeycomb (usually called a wall flow honeycomb)
In a checkerboard pattern shown in FIG. 20, the exhaust passage is not penetrated, that is, is not made through (flow-through) as in a normal ceramic honeycomb catalyst carrier, and the outlets and inlets of the adjacent passages are alternately closed. ).
The exhaust gas flows into the opening of the square prism that is open, but passes through the porous wall of the square prism because the outlet is closed,
It moves to the next passage. Accordingly, the porous ceramic honeycomb has a relatively high exhaust gas particulate matter trapping efficiency of about 80%, but requires a large honeycomb structure because the area for filtration and trapping is small. The biggest drawback is that the gas flow resistance is high because the particulate matter of the exhaust gas passes through the wall of the porous ceramics to be filtered.

[0009] The wall flow honeycomb is an infinite number of pores (open cells) in cordierite, silicon carbide and the like.
A porous ceramic honeycomb structure provided with
A generally known embodiment is that there are 200 square pillar pores per square inch, and one side of the square pillar pores is about 1.4 mm, the wall thickness is 0.36 mm, and the wall thickness is 0.36 mm. Is about 10 μm, and the length of a square pore is 160 mm.

As described above, since the wall E of the filter E of the wall flow honeycomb has a wall thickness of only 0.36 mm, the filtration time (passing time) is naturally short, so that the heating and burning time is short, and the particles passing therethrough are short. There is a disadvantage that the particulate matter (PM) cannot be completely incinerated.

The second example is called an "active system". When the filter is deposited on a filter (honeycomb wall) and clogged, it is incinerated and regenerated by a special mechanism using a burner or a heater. It was large and costly.

On the other hand, a third example is a continuously regenerating type particulate matter removal apparatus of a catalytic combustion type proposed by Johnson Matthey of the United Kingdom. This uses catalytic combustion without using a burner or a heater to recover clogging. The particulate matter removing device at the time of continuous regeneration of the catalytic combustion method is called a “passive type”, and the heat of the catalyst is utilized for incineration of the particulate material, not an electric heater. That is, an oxidation catalyst is placed in front of a filter (wall flow honeycomb) to generate nitrogen dioxide (NO ₂ ) which has a strong effect of oxidizing carbon with the catalyst, and at the same time, generates heat. In this particulate matter removing device, reaction heat generated naturally is used. Since only one filter is required and continuous incineration can be performed, the filter is smaller and less costly than the first conventional example, that is, a device for removing particulate matter of a ceramic fiber filter.

The fourth example, Engelhard, USA, is also a "passive method", using a filter (Wall Flow Honeycomb) in which the filter is coated with two types of metal catalysts having an oxidizing function. Oxidizes substances. In order to cause this catalytic reaction, it is necessary that the temperature of the exhaust gas passing through the filter be 350 ° C. or higher. However, since the exhaust gas temperature of a diesel engine is usually as low as about 200 ° C., the temperature of the particulate matter is lowered by 50 to 100 ° C. as close as possible to the engine or by adding an additive such as cesium oxide to the fuel (light oil). Or need to be burned. This fourth example also requires only one filter and can be continuously incinerated, so that it is smaller and less expensive than the first example (a device for removing particulate matter of a ceramic fiber filter).

Therefore, at the present time, the "passive" type catalytic combustion continuous regeneration type particulate removal apparatus using a wall flow honeycomb for the filter, that is, the third and fourth examples are the most promising. Have been watched.

[0015] However, the third example of the continuous mass removal apparatus of the continuous combustion type of the catalytic combustion system of Johnson Matthey of the United Kingdom uses sulfur having a strong oxidizing power contained in light oil used as a fuel for a diesel engine. Unless the S) content is reduced from the current 500 ppm to 50 ppm or less, there is a major drawback in that the oxidation catalyst for oxidizing carbon fine particles does not function. Therefore, it is necessary to wait for progress in improving the quality of light oil.

In the fourth example, since the exhaust gas temperature is much lower than the catalyst combustible temperature, the fuel is mixed with an additive such as cesium oxide to promote the oxidation, and the particulate matter is reduced by 50 to 100%. Some devices have been devised to increase the particulate matter removal rate by burning at a temperature lower by ℃, but this is not only costly, but also involves dispersing new compounds in the atmosphere, causing another concern. There are drawbacks.

In each of the third and fourth examples, there is a disadvantage that it is difficult to retrofit a diesel engine vehicle that is already running.

[0018]

A honeycomb carrying a three-way catalyst has been widely used as an exhaust gas purifying apparatus for automobiles and the like. This is a so-called flow-through type honeycomb in which exhaust gas flows in one direction in the honeycomb. With this transparent honeycomb, the particulate matter (P
Since it was thought that it was almost impossible to collect and process M), an apparatus for removing particulate matter from exhaust gas by filtration using the above-described filter has been proposed.
Therefore, the above-mentioned conventional particulate matter removal device for diesel engine exhaust is a method of filtering particulate matter,
A ceramic fiber filter is used for the filter, or a ceramic such as a ceramic honeycomb is used for the wall flow honeycomb. These materials have the drawback that the filter is not capable of performing the most efficient operation, and not being able to generate easily controllable electric heating (self-heating, called "automatic system"). For this purpose, the "active method" of the first and second examples in which the filter is heated by another heat source such as a burner, and the third and the other methods which function by increasing the temperature of the exhaust gas such as by utilizing the heat of catalytic reaction. The fourth example of the "passive method" is to eliminate the disadvantages of the continuous regeneration type of catalytic combustion. That is, it is effective immediately after starting the engine, can be operated continuously, completely incinerates particulate matter, has a simple structure, is easy to manufacture, is compact, high-performance and inexpensive, and can be retrofitted to existing diesel vehicles. It is an object of the present invention to provide a device for removing particulate matter in vehicle exhaust gas. Conventionally, as an apparatus for directly heating the exhaust gas in order to regenerate the particulate matter removing apparatus, FIG.
Structures (a) and (b) of No. 6 have already been disclosed. FIG. 16B shows that the particulate matter adhered to the ignition plug due to the particulate matter flowing backward in the passage and incomplete combustion was easily caused. FIG. 15 (b) in which this is improved is the second DPF
FIG. 16A shows that the valve is closed to collect particulate matter in the burner combustion chamber having the fuel injection nozzle and the ignition plug, the passage on the burner combustion chamber side is closed, and the fuel injection nozzle in the burner combustion chamber is closed. And to prevent the spark plug from being contaminated by the returning particulate matter. Each of these uses liquid fuel and has a spark plug a
A burner combustion chamber b having a burner is provided, and a dedicated compressor for the burner and a pump for pumping fuel are required.
DPF is required. Japanese Patent Application Laid-Open No. 60-78819 discloses a technique in which the exhaust gas of a separately provided combustion heater is introduced upstream of a catalytic converter. It only purifies. In Japanese Patent Application Laid-Open No. 12-186538, a liquid fuel is supplied to a combustion cylinder by a pump to vaporize and burn. The high-temperature combustion gas generated by the combustion type heater is supplied via a three-way valve → a combustion gas cooler → a combustion gas discharge passage →
It leads to an exhaust gas purification device including DPF. These combustions require a blower fan and require operation control by the CPU of the ECU, which is not only complicated and expensive, but also causes a shift in combustion timing, making stable combustion difficult and delicate combustion. It is difficult to control the temperature and amount. Further, the combustion gas contains little oxygen, and it was impossible to incinerate carbon particulate matter. Further, in the case of a conventional ceramic fiber filter or a filter type of a filtration filter comprising a wall-flow type ceramic honeycomb, ash (ash) generated by incinerating and regenerating particulate matter (PM) deposited on the filter is applied to the filter. There is a big problem that the pressure loss of the filter is increased by accumulation. In order to remove the ash deposited on these filters, it is necessary to apply a large mechanical impact. Therefore, as a countermeasure, Japanese Patent Application Laid-Open No. H11-34581 discloses a method in which a communication valve is opened and closed to cause exhaust gas to flow backward and a DPF. It is suggested that the ash deposited on the surface be backwashed and desorbed. Therefore, the conventional "combustion heater" using liquid fuel is not only complicated and expensive in operation control and the like by a spark plug, a pump, a compressor, and a CPU of an ECU, but also produces a shift in combustion timing, and is stable. The combustion was difficult, and the temperature and amount of combustion were difficult to control. In addition, it can itself produce particulate matter.

The above-described ceramic fiber filter used in the conventional diesel engine exhaust gas particulate removal apparatus has a large filtration area, is said to have a PM trapping efficiency of 70 to 80%, and has high reliability. There is a major drawback in that the collection efficiency is about 60% at the initial stage when the filter is new or regenerated.

In the case of a wall flow honeycomb, the filter has a very small pore size of 1 to 10 μm and is easily clogged, and is difficult to regenerate. Also, the pressure loss is large,
Heavy load on the engine. In addition, while filtration and regeneration are repeated many times, the ash contained in the particulate matter remains completely clogged, and the honeycomb has to be replaced. Furthermore, ceramics used as a material has a drawback that it is vulnerable to impact. In addition, since the conventional one uses ceramics, self-heating by energization cannot be performed. Separate heaters and burners are indispensable for regeneration.

The object of the present invention is to eliminate the disadvantages mentioned above. That is, low pressure loss, no clogging,
It is easy to regenerate, has a long life, uses catalytic combustion, can be regenerated by self-heating, and can be regenerated even during use.
It is an object of the present invention to provide a device for removing particulate matter in exhaust gas of a diesel vehicle, which has a simple structure and can be retrofitted to an off-the-shelf diesel vehicle.

[0022]

It has been known that fine particles (1 to 30 .mu.m) of carbon or the like contact or collide with a wall or the like during the flow and adhere to the fine particles. The inventor of the present invention has been developing a device for removing particulate matter from diesel engine exhaust gas using a metal honeycomb in which exhaust gas passes through the honeycomb.
(0-5000 μm), it has been found that the above-mentioned phenomenon that the carbon fine particles adhere to the wall surface occurs extremely effectively, and thereby particulate matter in diesel engine exhaust gas can be easily captured and removed. As a result of various experiments, the present invention has been completed. That is, the means for removing particulate matter according to the present invention is a conventional wall flow honeycomb,
Alternatively, instead of filtration using a filter such as a ceramic fiber laminated nonwoven fabric, trapping and collection on the metal foil wall surface, and incineration of particles passing through gaps between the metal foils and adhered particles of the metal foils. Therefore, continuous processing can be performed with small pressure loss and efficiency is high. This problem is solved by using a metal honeycomb formed of a thin metal plate provided at a predetermined interval. A material having a small airflow resistance, for example, a heat-resistant metal foil having a thickness of 20 to 100 μm and a width of 10 to 500 mm is used, and a metal honeycomb formed by winding or laminating the same so that the gap becomes 10 to 5000 μm is used. That is, the particulate matter in the exhaust gas comes into contact with or collides with the wall surface and is captured while passing through the gap between the metal foils formed of a fine honeycomb and having a predetermined interval.

Once the particulate matter once captured by the honeycomb is removed from the honeycomb without passing through the exhaust gas of the engine, the honeycomb itself is energized or heated to a high temperature by a heater, or the burner or the burner is removed. The problem is solved by supplying a high-temperature gas heated by a heater to the honeycomb and burning it to regenerate the honeycomb.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claims 1 to 3 uses a honeycomb formed of a thin metal plate having a predetermined gap. As such a metal foil, a material having a small airflow resistance, for example, a heat-resistant metal foil having a thickness of 20 to 100 μm is used, and a metal honeycomb obtained by winding or laminating the material so as to have a gap of 10 to 5000 μm is used. The heat-resistant metal foil constituting this honeycomb withstands the high temperature of exhaust gas,
It is desirable that the material be capable of conducting and heating when necessary. Further, a carrier capable of supporting a catalyst is preferable.

From the above, according to the present invention, heat-resistant steel (Fe) for a catalyst carrier having a thickness of the honeycomb of 20 to 100 μm is used.
-20Cr-5Al). By the way, Fe-20C
The electric resistance value (specific resistance) of r-5Al is 14 at 300 ° C.
6 (μΩ · cm).

When trapping particulate matter on the wall surface of the honeycomb, it is desirable that the exhaust gas contact surface area is as large as possible and that the flow path has a bend. When a honeycomb is formed with small gaps using corrugated metal foil, the surface that comes into contact with the gas has a very large area, and the bend becomes very large, and the particulate matter in the gas contacts or collides with this surface And is supplemented on the wall surface.

This is similar to a mechanism in which a carrier for a denitration catalyst or a desulfurization catalyst is formed in a honeycomb structure, and chemical substances in exhaust gas reaching the surface of the honeycomb adhere to the surface carrying the catalyst and react on the surface. ing.

According to the fourth aspect of the present invention, the wall surface of the honeycomb is more smooth than the smooth surface, and the protrusions such as whiskers are more likely to capture the particulate matter.
Once supplemented, it is difficult to leave. This can be achieved by, for example, oxidizing the honeycomb under predetermined conditions to generate whiskers on the surface, or by applying a wash coat to the surface.

According to a fifth aspect of the present invention, when the particulate matter is removed by adhering to the wall surface of the honeycomb, the particulate matter is positively or negatively charged by corona discharge or the like,
On the other hand, when the honeycomb is charged to the opposite charge and an electric attraction force is exerted between the particulate matter and the honeycomb wall surface, the particulate matter is attracted to the honeycomb wall surface and the adsorption speed increases.

According to a sixth aspect of the present invention, when the particulate matter in the exhaust gas of a diesel engine composed of carbon fine particles is incinerated, the ignition point of the particulate matter is about 500 ° C.
The incineration cannot be performed unless the exhaust gas or the surface of the honeycomb is heated above this temperature. However, TiO ₂ , V ₂ O ₅ , Pt
By using an oxidation catalyst such as
It can be lowered to 0 ° C to 400 ° C. In the present invention, an oxidation catalyst is supported on the surface of a honeycomb made of a metal foil, and the particulate matter is sufficiently and easily brought into contact with the catalyst, and can be incinerated even at a low temperature.

According to the present invention, the particulate matter adhered to the wall surface of the honeycomb narrows the exhaust gas passage and increases the pressure loss of the honeycomb. It is a device for reproducing. By energizing the honeycomb itself, the walls of the honeycomb generate heat,
The temperature is raised to a temperature at which the particulate matter can be incinerated, that is, 500 to 600 ° C. when the catalyst is not supported, and 300 to 400 ° C. when the catalyst is supported.

This is accomplished by dividing the honeycomb into a plurality of disk-type honeycombs, and further dividing each disk-type honeycomb into a plurality of sections. The material can be incinerated to regenerate the honeycomb. Although it is possible to regenerate the entire honeycomb at once by energizing it, a large amount of current is required at a time, and a large generator for replenishing electricity needs to be mounted on the diesel vehicle. But,
By reproducing in order for each disk or for each section, the required amount of electricity can be averaged, and the capacity of the generator can be reduced.

In the regeneration of the honeycomb, since the exhaust gas from the engine contains little oxygen, the particulate matter cannot be sufficiently incinerated even at a high temperature. Therefore, air is sent from the outside to the exhaust gas pipe upstream of the honeycomb. .

According to a ninth aspect of the present invention, there is provided a method of installing a separate electric heater or burner instead of energizing the honeycomb itself. This electric heater is located upstream of the honeycomb,
Alternatively, the honeycomb structure is disposed between the honeycomb disks or on the side surface of the honeycomb, whereby the honeycomb is heated to burn and regenerate the particulate matter. In addition, the burner is installed in the exhaust gas pipe on the upstream side of the honeycomb, or a combustion chamber equipped with a burner is provided, and by joining this combustion chamber and the exhaust gas pipe on the upstream side of the honeycomb, the combustion gas is sent to the honeycomb and the honeycomb is heated. And play.

The invention described in claims 10 to 12 is the first invention.
In the invention, the fins and the cross-type honeycomb are used as a device for efficiently transferring the heat of the combustion gas to the exhaust gas in the burner installation mode of the invention.

A thirteenth aspect of the present invention is to provide a denitration function by supporting a denitration catalyst on a part or the whole of a honeycomb. This is an apparatus which serves both as a particulate matter removal device and a denitration device. . Diesel engines are usually equipped with a denitration device, so by using both, the equipment is simplified and the installation space is reduced. Also, less electricity and fuel is required to heat the honeycomb.

According to a fourteenth aspect of the present invention, two honeycombs are installed, and one of them is used as a spare. When the particulate matter has sufficiently adhered to one honeycomb and the pressure loss has increased, the unit is switched to a standby unit. Switch to the spare machine,
Regenerate the honeycomb with increased pressure loss while continuing to remove particulate matter from engine exhaust gas.

FIG. 22 is an example of a further development of the cross type honeycomb. In this example, the wave is basically formed in such a manner that the corrugated waves meander in the longitudinal direction and meander regularly, and a plurality of such waves are laminated so that the meandering waves are reversed in a so-called back-to-back manner. In this case, the number of collisions with the metal foil increases as compared with the case where the exhaust gas flows from the direction of the arrow B of the large wave. Further, by appropriately changing the shape of the corrugated wave and the large wave, many forms can be made. In the above,
Although the particulate matter removal device for diesel vehicle exhaust gas with a diesel engine has been described, the present invention is not limited to this. Land engines, marine engines, cogeneration, and other particulate materials used in large and small diesel engines It can be used to treat exhaust gas containing substances. Hereinafter, the present invention will be described in detail with reference to examples.

[0039]

Embodiment 1 Embodiment 1 will be described below with reference to the drawings. As shown in Figure 1, particulate matter removal device (DPF)
Has a case 2 in which a metal honeycomb 1 formed by winding a metal foil is placed. The honeycomb 1 is passed through a strip-shaped fixing plate 3 at the end face, and each metal foil of the honeycomb and the case 2
Is fixed by brazing or welding by laser. This fixing method is the same as the method described in Japanese Patent Application Laid-Open No. 4-186198. The particulate matter of about 10 μm contacts or collides with the honeycomb wall while passing through the honeycomb and is captured.
As the honeycomb of the first embodiment, a tape-like material obtained by cutting a heat-resistant metal foil (Fe-20Cr-5Al) having a thickness of 50 μm to a width of 150 mm with a slitter is used. And FIG.
As shown in (a), one sheet is formed as a flat plate 1a and the other sheet is formed as a corrugated sheet 1b. The shape and height of the wave are formed so that the maximum gap between the flat plate 1a and the corrugated plate 1b becomes about 1500 μm when the product is obtained. These flat plates 1
a and the corrugated sheet 1b are overlapped and wound many times like a cardboard. Thus, a honeycomb having a diameter of 120 mm and a length of 150 mm is obtained.

In another embodiment of the honeycomb, as shown in FIG. 2 (b), the corrugated plate 1b of FIG. 2 (a) is formed into an oblique corrugated plate 1c having unevenness in an oblique direction so that a gap of about 1500 μm is formed. It was done. In this case, the size of the gap is more stable than that in FIG. 2A, and the number of collisions of the ultrafine particulate matter flowing in by the oblique corrugated plate 1c is increased, so that the collection efficiency is increased. FIG. 2 shows another embodiment of the honeycomb.
(C) is a honeycomb formed by winding a corrugated sheet 1c and a corrugated sheet 1d corrugated in a diagonal direction different from each other back to back and winding many times to form a honeycomb, which is called a cross-type honeycomb. is there. In this case, the number of collisions of ultrafine particulate matter is further increased as compared with that shown in FIG. Further, as shown in FIG. 2D, it is preferable to increase the number of collisions of the particulate matter with the wall surface by forming irregularities such as by providing a concave portion 1e inside the crest of the corrugated sheet 1b.

As shown in FIG. 3, it is preferable that the surface of the honeycomb has a sharp edge. Low ventilation resistance is required. FIG. 3A shows a heat-resistant metal foil f having a thickness of 50 μm.
FIG. 4 is a schematic diagram showing an edge g while cutting the sheet with a roll slitter. (B) is a schematic diagram showing a state in which the edge of (A) is sharpened. This sharpening may be mechanical polishing with abrasive grains or roll rolling of the edge, but may be a method of rounding the tip by electrolytic polishing or chemical polishing. The gap h at this time is 10
0 μm. This has a great effect of reducing the ventilation resistance of the inflowing exhaust gas.

[0042]

[Experiment 1] A honeycomb specimen was manufactured, and the removal rate of particulate matter was measured. Honeycomb has a thickness of 50 μm and a width of 120
mm by winding metal foil. 50mm diameter
The test was conducted in a case having a length of 150 mm. Simulated particles were used as the particulate matter. The experimental apparatus and the experimental method are shown below. FIG. 4 shows the outline of the experimental apparatus. The experimental apparatus includes a particle generator, a test section for mounting a test body, a particle concentration measuring device, and a blower as shown in FIG. An apparatus (TOPAS SLG250) for condensing stearic acid with NaCl particles as nuclei was used in the particle generation section. Atmospheric dust was also used as sample particles. The measurement of the particle number concentration by particle size on the upstream and downstream of the test piece was performed by a particle counter or a photo counter connected to the sampling port. Furthermore, the dust load characteristics of the test specimen were measured using an apparatus that measures the dust mass concentration from the attenuation of the transmitted light amount of the dust concentration using a photomultiplier tube. The pressure loss of the test body was measured by a differential pressure gauge using a pressure transducer. The experimental conditions are shown in Table 1. The numbers in FIG. 4 indicate the following, respectively. That is, 30 is an aerosol, 31 is a flow meter, 32 is a HEPA filter, 33 is a mixer, 34 is a particle counter or photo counter, 35 is a test sample, 36 is a differential pressure gauge, 37 is a particle counter or photo counter, 38 is an orifice, 39 is a blower.

[0043]

[Table 1]

The measurement results are as shown in FIG. The measurement results of the number-based collection efficiency for each particle size are shown using the passing speed as a parameter. The particles used are atmospheric dust. Passing speed 3cm / s
The trapping efficiency is small regardless of the particle size. Increasing the flow rate tends to increase the efficiency of capturing particles greater than 1 μm, but is not always monotonous with increasing filtration rate. FIG. 6 shows the measurement results of the dust addition characteristics. The vertical axis is the collection efficiency defined by the dust concentration ratio between the upstream and downstream of the test specimen, and the horizontal axis is the dust load per unit cross-sectional area of the test specimen (C: particle mass concentration, v: filtration speed, t: load time). is there. Although the collection efficiency immediately after the start of the load is almost zero, the collection efficiency increases with the increase in the dust load, and eventually exceeds 90%. This is thought to correspond to an increase in the shielding effect of the tree structure of the particles collected on the honeycomb surface of the test specimen, and by making good use of this, low pressure loss and high collection efficiency were achieved. Filter characteristics.

[0045]

Embodiment 2 In Embodiment 2, a thin metal sheet whose surface is oxidized is used for a honeycomb. This embodiment 2
20 μm thick heat-resistant metal foil (Fe-20Cr-5A)
1) is formed by corrugating with a forming roll having a pitch of module 0.3 according to the gear standard, and a cross-type honeycomb in which oblique corrugated sheets are backed to each other has a gap of about 300 μm. This is cut into a width of 150 mm, and is wound many times in the same manner as in Example 1. By oxidizing this metal foil, a surface with many undulations can be produced as shown in the micrograph of FIG. FIG. 7 is a 6000 × electron micrograph. By adopting such a state, it is possible to increase the capture rate of the particulate matter that contacts or collides with the metal surface, and it is possible to prevent the particulate matter once captured from being released. FIG. 8 shows the state before the heat treatment.
It is an electron microscope photograph of 00 times.

[0046]

Third Embodiment In a third embodiment, as shown in FIG. 9, a round bar electrode 4 is provided in an exhaust gas pipe, a discharge electrode is used, and a surrounding pipe 5 is used as a collecting electrode to perform corona discharge between the electrodes.
The collector electrode is grounded so that a high DC voltage can be applied by the high voltage generator 6 between the discharge electrode and the collector electrode. When the collector electrode is grounded in the same manner, the negatively charged ions and particulate matter are attracted to the surrounding pipe 5 and the honeycomb 1 by Coulomb force. The high voltage generator 6 has the same structure as the high voltage generator of the ignition device of the internal combustion engine, and includes a coil unit, a transistor, and a signal generator. By corona discharge, hydrocarbons and oxygen in the exhaust gas are excited, dissociated, and ionized to have a negative charge. These ions also adsorb to the particulate matter, and the particulate matter also has a negative charge. The charged particulate matter is
Due to Coulomb force in addition to adhesion due to contact and collision with the honeycomb wall, more strongly attracted, more particulate matter,
It is more strongly adsorbed on the honeycomb wall.

[0047]

Embodiment 4 In Embodiment 4, a honeycomb is coated with a metal foil surface oxidation catalyst. By coating the oxidation catalyst on the surface of the honeycomb, the combustion temperature of the particulate matter can be reduced to 350 ° C to 400 ° C. Examples of the oxidation catalyst include TiO ₂ , V ₂ O ₅ , and Pt. If the exhaust gas temperature is 350 ° C or more, or if the honeycomb metal foil is 3
If the temperature is higher than 50 ° C., the particulate matter is incinerated at the same time as it contacts or collides with the honeycomb wall. However, when the temperature is lower than 350 ° C., such as during low-speed operation, the particulate matter first adheres and accumulates on the honeycomb wall, but when heated for honeycomb regeneration, the interface between the honeycomb wall at 350 ° C. or higher and the adhering particles is increased. It is completely incinerated as soon as more oxidation occurs. In addition, the particulate matter during low-speed operation contains a large amount of unburned oil and light oil (mainly hydrocarbons), and combustion is relatively easy. Since the particulate matter itself is incinerated and disappears, the oxidation catalyst does not lose its oxidizing ability due to the particulate matter.

[0048]

Fifth Embodiment In the fifth embodiment, the oxidation catalyst is coated on the surface of the metal foil of the honeycomb, so that the hydrocarbon contained in the exhaust gas can be incinerated and removed.

[0049]

[Embodiment 6] Embodiment 6 is a mode of honeycomb regeneration by self-energization. When the honeycomb on which the particulate matter adheres and accumulates is regenerated by energizing, the honeycomb 2 is divided in the axial direction as shown in FIGS. In this example, the thickness is 20μ
A metal foil having a width of 20 mm and a width of 20 mm is corrugated and wound around the cross-type honeycomb of Example 1 to form a disk having a diameter of 80 mm and a thickness of 20 mm. Then, the honeycomb 7 divided into the disk shape is further formed into the honeycomb 8 divided into the circumferential shape.
The amount of electricity required for reproduction can be averaged by sequentially heating and heating each, so that the amount of electricity required at a time can be reduced. The divided disk-shaped honeycombs 8 can be insulated from each other by interposing a (Nextel) heat-resistant insulating material 9 manufactured by 3M (USA). The insulation between the metal foils in the divided honeycomb 8 can be insulated by coating the metal foil with a heat-resistant insulating film. The heat-resistant metal foil (Fe-20C) having a thickness of 20 μm used in the present invention.
r-5Al) is 20 mm wide and 2 m long with an electrical resistance of 7
It is 30Ω, and the temperature rises to 800 ° C. in a windless state at a current of 200 V and 20 A. Since a part of this heat is also used for heating the exhaust gas, the temperature of the honeycomb itself becomes 550 ° C. By winding the metal foil of this length, the honeycomb 8 divided into one section, that is, the circumferential shape is formed. In the case of the metal foil having a length of 2 m used in the present embodiment, 6 to 8 sections are formed in a disk-shaped honeycomb having a diameter of 80 mm. An electric terminal is provided in each section, and a switching controller 10 and a timer 11 for sequentially switching and supplying electricity are provided. The electricity required for regeneration can be provided by an electricity supply device 12 such as a storage battery or a generator loaded on the vehicle.

[0050]

[Embodiment 7] Embodiment 7 is an embodiment of honeycomb regeneration using a separate electric heater. To regenerate the honeycomb, the honeycomb may be heated or the exhaust gas may be heated. However, as shown in FIG. 13, an electric heater 13 is provided on the upstream side of the honeycomb, and the exhaust gas is first heated by supplying electricity to the heater. By further heating the honeycomb 1 with this exhaust gas, both the heat of the exhaust gas and the heat of the honeycomb 1
Particulate matter can be incinerated. Also, as shown in FIG. 14, an electric heater 13 is provided on the side surface of the honeycomb 1, and an electric current is supplied to the electric heater 13 to heat the honeycomb 1 and incinerate the particulate matter. However, in these cases, since both the amount of heat for increasing the temperature of the honeycomb body and the amount of heat for increasing the temperature of the exhaust gas are required at the same time, a large amount of electricity is required at one time, and the electricity supply device 12 is large.

[0051]

Embodiment 8 As another honeycomb regeneration method, FIG.
As shown in 5, a burner 14 can be installed upstream of the honeycomb 1 to burn a fuel such as propane gas or light oil, and this combustion gas can be used for regeneration. At this time, the combustion chamber surrounding the burner is installed in the exhaust gas pipe 15 as shown in FIG. 15 (a), and furthermore, exhaust gas swirling blades 17 and fins are attached to the outer surface of the combustion chamber 16 so that the combustion chamber 16 Prevents heat loss to the outside and can be used efficiently for exhaust gas heating. In this embodiment, liquefied propane gas, LPG
(Liquefied petroleum gas), LNG (liquefied natural gas) and the like are burned by a gas burner, and the combustion heat is converted into low-temperature exhaust gas (200 to 300 ° C. during low-speed operation) by a predetermined particulate matter (P
M) It is used as a heat source for heating to a combustion temperature of 500 to 600 ° C (350 to 400 ° C when a catalyst is used). Therefore, a large amount of heat is not required (for example, 2000 c
Exhaust gas during low-speed diesel engine operation at 100 ° C
The calorie required for additional heating is about 24 kcal / min). The combustion chamber 16 by the burner 14 is characterized by being provided in the exhaust gas pipe 15 upstream of the honeycomb 1 as shown in FIG. And the flue 18 is the exhaust gas passage 15
a, 15b, and 15c occupy a part thereof, and the surface thereof is subjected to heat exchange heating of exhaust gas. Further, if necessary, the flue 18 is provided with a spiral exhaust gas swirl vane 17 to enlarge the heat transfer surface, and the introduced exhaust gas is swirled around the flue 18 along the exhaust gas swirl blade 17 in a cyclone shape. While reaching the honeycomb 1.
At this time, the exhaust gas mixed with the high-temperature combustion gas is supplied to the front surface of the honeycomb 1 while being dispersed at a uniform temperature. Further, by utilizing the cyclone effect, the combustion gas and / or air (not shown) are drawn in as necessary to smooth the combustion of the gas burner and completely burn the particulate matter (PM). Another method of mixing high-temperature combustion gas and low-temperature exhaust gas and dispersing them into the front surface of the honeycomb 1 at a more uniform temperature is to use a member 19 as shown in FIG. is there. In this case, if necessary, a cross-type honeycomb 19 constituted by laminating or winding a corrugated sheet corrugated in an oblique direction and another corrugated sheet back to back is provided in a part of the passage 15c. The cross-type honeycomb 19 has an excellent ability to stir the exhaust gas and the combustion gas passing therethrough.
Alternatively, a rectifier 21 can be provided at the entrance of the honeycomb 1. As a result, the temperature and the flow rate of the combustion gas and the exhaust gas become uniform and are supplied to the honeycomb 1. The cross-type honeycomb 19 and the rectifier 21 may be provided in an overlapping manner.
Further, reference numeral 20 shown in FIG. 15A denotes a cross-type honeycomb provided in a part of the flue 18. This increases the flow resistance by increasing the slope of the oblique wave, and can prevent exhaust gas from flowing back into the combustion chamber 16. In these embodiments, the flue gas is stably burned by providing the flue. Furthermore, since the amount of air, that is, the (air-fuel ratio) can be freely set, the combustion temperature of the gas,
The amount of oxygen contained in the burned gas can be freely set, and the amount of nitrogen oxide to be discharged can be adjusted. Furthermore, when the temperature of the exhaust gas is increased by the burner, the catalyst does not need to be used, so that the temperature easily rises to 500 ° C. or more, and even if the sulfur of the diesel fuel is large, the carbon fine particles of the exhaust gas of the diesel vehicle are efficiently produced. It can now be removed. 22 in FIG.
Is a fuel gas supply pipe, and 23 is an air supply pipe. The combustion gas mixes with the exhaust gas and enters the honeycomb 1, but can be discharged outside the honeycomb 1 as needed. As a member constituting the combustion chamber 16 and the flue 18, a copper alloy having good heat conductivity,
Alternatively, a stainless steel foil having a thickness of 20 μm can be exemplified. The gas burner can use an ignition heater that functions with very little power consumption, so that the device is small and simple and the cost is low. In addition, it is completely burned instantaneously and can control the thermal power freely, and is optimal as a heat source for heating diesel vehicle exhaust gas containing particulate matter. As fuels, cylinders and cartridges of LPG (liquefied petroleum gas) and the like have already been proven in safety and are easy to use.

[0052]

Embodiment 9 Embodiment 9 is an example in which a denitration catalyst is used for a honeycomb metal foil. As shown in FIG. 17, a part of the honeycomb 1 carries a denitration catalyst, and an exhaust gas pipe upstream of the honeycomb is provided with a device (not shown) for supplying an ammonia source. Can be made. Since the denitration reaction occurs at a high temperature, the exhaust gas temperature
It must be at least 0 ° C. Increasing the exhaust gas temperature also facilitates incineration of particulate matter, so that both can be used for both, and electricity or fuel for exhaust gas heating can be saved. Further, since the denitration and the particulate matter can be removed by the honeycomb having the same structure, they can be integrated, the whole apparatus can be simplified, and the installation space can be reduced.

[0053]

Embodiment 10 Embodiment 10 is an example in which a spare machine is provided at the time of honeycomb regeneration. As shown in FIG. 18, a honeycomb spare device is provided, and the honeycomb is switched to the spare device during honeycomb regeneration. Exhaust gas pipes are connected to the two honeycombs 1 on both the inlet side and the outlet side, and an inlet switching valve 26a and an outlet switching valve 2
6b is installed. When one of the honeycombs 1 is filled with particulate matter and the pressure loss is increased, the apparatus is switched to a standby machine. Also in this case, the reproduction can be performed while running without stopping the engine. The honeycomb 1 having a large pressure loss closes the inlet-side switching valve 26a and the outlet-side switching valve 26b before and after the honeycomb, connects to the regeneration pipe 27, and
Air heated to at least 00 ° C is sent. A part of air is newly taken in (pipe is not shown), and a part of the combustion gas of the particulate matter is extracted (pipe is not shown). The air is circulated while burning the particulate matter. In this case, since the amount of oxygen to be heated is very small and the amount of air to be heated is small, the amount of electricity for burning the particulate matter is small. The honeycomb 1 whose reproduction has been completed waits for the next use.

In the above description, a gaseous fuel such as propane is exemplified as the fuel for the burner. However, the present invention is not limited to this, and liquid fuels such as gasoline and light oil and others can be used. In addition, not only a denitration catalyst but also a three-way catalyst can be used together.

[0055]

According to the present invention, compactness, low pressure loss, no clogging, easy regeneration, long life,
Uses catalytic combustion, can be regenerated by self-heating, can be regenerated during use, has a simple structure, and can be retrofitted to off-the-shelf diesel vehicles.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2A is an enlarged perspective view showing a main part of the honeycomb of FIG. 1; FIG. 2B is an enlarged perspective view showing a main part of the honeycomb of FIG. FIG. 2C is FIG.
It is a perspective view which expands and shows the principal part of the honey-comb. FIG. 2D is a perspective view showing an enlarged main part of the honeycomb of FIG.

FIG. 3 is a partial cross-sectional view showing an edge of a honeycomb. (A) is an enlarged schematic view showing an edge as it is slit, and (B) is an enlarged schematic view showing an edge whose tip is rounded.

FIG. 4 is an example of a dust mass concentration measuring device.

FIG. 5 is a diagram showing the measurement results of the number-based collection efficiency for each particle size.

FIG. 6 is a graph showing measurement results of dust addition characteristics.

FIG. 7 is an electron micrograph (magnification: 6000) of a heat-resistant metal foil subjected to heat treatment twice under predetermined conditions.

FIG. 8 is an electron micrograph (× 6000) of a heat-resistant metal foil before heat treatment.

FIG. 9 is a perspective view showing a third embodiment of the present invention.

FIG. 10 is a perspective view showing a sixth embodiment of the present invention (a honeycomb disk diagram).

FIG. 11 is a perspective view showing a sixth embodiment of the present invention (a honeycomb section diagram).

FIG. 12 is a perspective view showing an embodiment 6 of the present invention (electric connection state diagram).

FIG. 13 is a perspective view showing a seventh embodiment of the present invention (front electric heater).

FIG. 14 is a perspective view showing a seventh embodiment of the present invention (a side electric heater).

FIG. 15 (a) is a perspective view showing Embodiment 8 of the present invention. FIG. 15B shows an example of a conventional apparatus for directly heating exhaust gas.

FIG. 16 is an example of a conventional apparatus for directly heating exhaust gas.

FIG. 17 is a perspective view showing Embodiment 11 of the present invention.

FIG. 18 is a perspective view showing Embodiment 12 of the present invention.

FIG. 19 is a perspective view showing a conventional ceramic fiber structure.

FIG. 20 is an explanatory view of a conventional filter switching type particulate matter removing device.

FIG. 21 shows a conventional ceramic honeycomb structure (wall flow honeycomb). It is a perspective view.

FIG. 22 is a perspective view showing another example of the cross type honeycomb of the present invention.

[Explanation of symbols]

A-filter, B-filter, C-switching valve, D-exhaust pipe, E-filter (wall flow honeycomb) a-spark plug, b-burner combustion chamber, c-second DP
F1. Honeycomb 1a. Flat plate 1b. Corrugated sheet 1c. Oblique corrugated sheet 1d. Corrugated sheets corrugated in different oblique directions 1e. Corrugated plate recess 1f. 50μ heat resistant metal foil 1g. Edge 1h. Gap 2. Case 3. Fixing plate 4. Round rod electrode 5. Surrounding pipes 6. High voltage generator 7. 7. Honeycomb divided into a disk shape 8. Honeycomb divided circumferentially Heat resistant insulating material 10. Controller 11. Timer 12 Electric supply device 13. Electric heater 14. Burner 15. Exhaust gas piping 15a. Passageway 15b. Passage 15c. Passage 16. Combustion chamber 17. Exhaust gas swirl blade 18. Flue 19. Cross-type honeycomb 20. Cross-type honeycomb 21. Rectifier 22. Fuel gas supply pipe 23. Air supply pipe 24. Particulate matter removing unit 25. Denitration unit 26a. Inlet side switching valve 26b. Outlet switching valve 27. Regeneration pipe 28. Circulation fins 29. Electric heater 30. Wire mesh

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F01N 3/02 341 F01N 3/02 341J 4D058 341P B01D 45/08 B01D 45/08 B 46/00 302 46/00 302 46 / 42 46/42 B 53/94 B03C 3/02 B B03C 3/02 3/36 A 3/36 3/45 C 3/45 B 3/47 3/47 3/60 3/60 3/74 Z 3 / 74 F01N 3/08 A F01N 3/08 B 3/20 N 3/20 3/24 E 3/24 B 3/28 301C 3/28 301 B01D 53/36 103C (72) Inventor Hiroo Masaki Kobe, Hyogo Prefecture 4-7-22 Migatadai, Nishi-ku, Yokohama F-term (reference) GB10W HA14 HA46 HB03 HB07 4D031 AB08 AB25 AB29 BA01 BB08 DA05 4D048 AA14 AA24 AB01 BB02 CD03 4D054 AA03 BA02 BA08 BC06 BC07 BC21 BC25 BC30 DA09 DA11 EA16 EA26 4D058 JA34 KB12 MA42 MA43 MA4 4 QA01 QA03 QA05 QA06 QA17 SA08 TA06

Claims (14)

[Claims] An apparatus for removing particulate matter (DPF) from diesel engine exhaust gas has a thin metal honeycomb structure as a main part, the metal honeycomb being a flat plate and a corrugated plate made of metal foil, and a flat plate and corrugations. A plate, or a corrugated plate and another corrugated plate, are formed by winding or laminating a large number of times with a predetermined gap therebetween, and the particulate matter is captured by contacting or colliding with the wall surface of the honeycomb while passing through the gap. An apparatus for removing particulate matter from exhaust gas of a diesel engine, characterized in that: 2. The honeycomb has a gap of 10 to 5000 μm.
2. The particulate matter removing device for diesel engine exhaust gas according to claim 1, wherein 3. The apparatus for removing particulate matter from diesel engine exhaust gas according to claim 1, wherein said honeycomb has a length of 10 to 500 mm. 4. The particulate matter of diesel engine exhaust gas according to claim 1, wherein a whisker is formed on the surface or a wash coat or the like is formed after partially or entirely oxidizing the honeycomb. Removal device. 5. The apparatus according to claim 1, further comprising a device for charging particulate matter in the exhaust gas to positive or negative by corona discharge or the like, and a device for charging the honeycomb to negative or positive. A device for removing particulate matter from diesel engine exhaust gas. 6. The apparatus for removing particulate matter from diesel engine exhaust gas according to claim 1, wherein an oxidation catalyst is supported on a part or all of the honeycomb. 7. The particulate matter of diesel engine exhaust gas according to claim 1, wherein said honeycomb is formed of one or more layers of disc-type honeycombs, and can be energized and heated as required. Removal device. 8. The diesel engine exhaust particulate according to claim 1, wherein each layer of said disk-type honeycomb is divided into one or a plurality of sections, and each section can be electrically heated as required. Material removal device. 9. The apparatus for removing particulate matter from diesel engine exhaust gas according to claim 1, wherein said honeycomb is provided with a regeneration means such as an electric heater or a burner. 10. A combustion chamber and a flue or a flue of the burner are provided in an exhaust gas passage upstream of the honeycomb, and a spiral fin is provided in the flue as required. Item 10. An apparatus for removing particulate matter from diesel engine exhaust gas according to item 9. 11. The apparatus for removing particulate matter from diesel engine exhaust gas according to claim 9, wherein a cross-type honeycomb is provided in a part of a flue and / or a part of a passage of a combustion chamber of the burner. . 12. The particulate matter removal from exhaust gas of a diesel engine according to claim 9, wherein a straightening body is disposed near an inlet of the particulate matter removal device downstream of the combustion chamber of the burner. apparatus. 13. A denitration catalyst and / or a three-way catalyst is supported on a part or all of the honeycomb.
3. The apparatus for removing particulate matter from diesel engine exhaust gas according to any one of 2. 14. A diesel engine exhaust gas according to claim 1, wherein two honeycombs are installed, one is used as a regular one, one is used as a spare machine, and the spare machine is used during the regeneration of one car. Particulate matter removal equipment.