KR101379955B1 - A Cascade Type DPF for Purifying Exhaust Gas - Google Patents

Abstract

The present invention relates to an exhaust purification apparatus of a multi-stage reduction method to reduce smoke in stages while passing through a plurality of metal filters, and an object of the present invention is to combine an oxidation catalyst device and a metal filter with a plurality of polishing beds. This step is to provide a multi-stage reduction type exhaust purification apparatus capable of increasing the overall smoke reduction performance while reducing the amount of smoke that is to be reduced in each portion, that is, the load on each portion. In addition, another object of the present invention, it is possible to freely adjust the size according to the performance required by the size of each part constituting the exhaust purification apparatus, and also to utilize the passage space, etc. It is an object of the present invention to provide an exhaust purification apparatus of a multistage reduction method that hardly increases the required space. The apparatus of the present invention is particularly useful when applied to two types of reduction devices (partial DPFs) in which the removal rate of particulate matter in diesel exhaust is defined as 50% or more.

Exhaust purification, soot reduction, metal filter, polishing bed, multi-stage reduction, cascade method, partial reduction device, partial reduction device, partial reduction device

Description

Multi-stage reduction type exhaust gas purification device {A Cascade Type DPF for Purifying Exhaust Gas}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust purification apparatus of a cascade type, and more particularly, to an exhaust gas purification apparatus of a multistage reduction method, in which soot is reduced in stages through a plurality of metal filters.

Automotive internal combustion engines generally operate using gasoline or diesel fuel. Gasoline cars are used in general passenger cars due to their low power and quietness and quick response due to their low noise and vibration. However, gas emitted from gasoline automobiles is considered to be an important factor for increasing global warming, and this problem is more prominent in the present time of increasing environmental problems. On the other hand, diesel cars have high durability and engine efficiency compared to gasoline cars, and their efficiency is 20 ~ 30%, which is excellent in terms of fuel efficiency and power, and thus they have been mainly applied to large vehicles such as trucks and buses. In addition, diesel vehicles have the advantage of low global warming due to the low amount of CO ₂ , CO, THC and evaporated hydrocarbons. The demand for cars continues to grow. However, nitrogen oxides (NO _x ) and particulate matter (PM) contained in a large amount of exhaust gas of diesel cars are recognized as the main cause of air pollution, accounting for 40% of the total air pollution. In production, environmental regulations are strictly applied. There are trade-offs between countries in terms of emissions of nitrogen oxides and particulate matter, and each country regulates the degree of occurrence according to policy requirements. However, in the era of high oil prices, diesel cars, which are more efficient than conventional gasoline cars, have been spotlighted. Accordingly, in order to reduce the emission of air pollutants generated in proportion to the production of diesel cars, developed countries have exhausted diesel engine exhaust gas. Increasingly, regulations on pollutant content are being tightened.

As a countermeasure to satisfy the emission regulations of internal combustion engines, pretreatment technologies aimed at reducing the generation of pollutants, such as fuel improvement, combustion methods, and engine improvements, and exhaust gas discharge ports It is divided into post-treatment technology to purify the exhaust gas generated by mounting. Although steady research and development is being conducted in each field, post-treatment technology is currently considered to be more advantageous for commercialization, and thus, more research and development is being conducted on post-treatment technology. Such post-treatment techniques include (1) an oxidation catalyst for purifying unburned hydrocarbons (CO) in particulate matter (PM), and (2) a particulate removal filter for filtering particulate matter (PM) through a filter. Filter (hereinafter referred to as 'DPF'), and (3) DeNO _x catalyst system for decomposing or reducing nitrogen oxides (NO _x ) under reducing atmosphere. For example, hybrid post-processing devices such as DPF systems with catalytic filters are widely used.

FIG. 1 shows an example of an exhaust purification apparatus generally used in two types of abatement apparatuses (reduction apparatuses having a reduction rate of particulate matter of 50% or more). The exhaust gas is circulated in the direction indicated by the arrow in FIG. 1, and firstly, some CO, THC, NOx, SOF (Soluble Hazardous Substances), etc. are removed while passing through an Oxidation Catalyst (100 '). Some of the soot is removed. In the oxidation catalyst apparatus 100 ′, harmful substances are decomposed by using a catalytic reaction. Therefore, most of the oxidation catalyst device 100 ′ almost eliminates other harmful substances (CO, THC, NOx, SOF), but the soot removal rate is not so high. In detail, when the ceramic honeycomb is used as the oxidation catalyst device, the soot is not removed, and when the metal catalyst support is used, the soot reduction function and the function of reducing the soot as well as the catalyst support are used when designing the internal structure of the support. Can be made to have at the same time. After passing through the metal filter 200 ′, most of the remaining harmful substances and the soot are removed. When each harmful substance is reduced to 100% while passing through the entire exhaust purification apparatus, in general, each harmful substance in the conventional exhaust purification apparatus is reduced as shown in Table 1 below.

Hazardous Substances Oxidation catalysis apparatus 100 ' Metal filter (200 ') CO, THC 50% to 100% 0% to 50% NO (→ NO ₂ ) 50% to 100% 0% to 50% PM SOF 50% to 100% 0% to 50% Soot 0% to 50% 50% to 100%

On the other hand, in some cases, such as when the exhaust gas contains a large amount of harmful substances, or when the amount of the exhaust gas itself is very large, there is a need for an exhaust purification apparatus having a performance capable of reducing more harmful substances. It is clear that the longer the path through which the exhaust gas passes through the exhaust purification device is good for removing more harmful substances, especially in the case of metal filters to remove soot. As shown in FIG. 1 and Table 1, in the case of a conventional exhaust purification apparatus in which an oxidation catalyst device and a metal filter are integrally combined, a plurality of exhaust purification apparatuses are provided or performance is increased by increasing the volume of the exhaust purification apparatus. Is increased. By the way, in the case of the conventional exhaust purification apparatus, in order to increase the performance as necessary, the volume of the exhaust purification apparatus itself becomes large too much, and it becomes very difficult to equip the vehicle.

In addition, in the case of the exhaust purification device previously installed in the vehicle, even if the smoke is reduced with sufficient performance based on the initial product release, the internal combustion engine of the vehicle may age and increase the generation of smoke. In this case, even if a new exhaust purification device is newly replaced, smoke cannot be reduced with satisfactory performance. In particular, even in this case, even if a higher performance exhaust purification apparatus is used as described above, increasing the performance increases the volume of the exhaust purification apparatus, which is larger than the volume of the originally installed exhaust purification apparatus. There is a problem that it is impossible to replace the device.

In addition, when the capacity of the oxidation catalyst device or the metal filter is increased in this way, the following problems are also inevitable. For example, in the case of a metal filter, if a certain amount of soot is accumulated, the exhaust gas cannot pass through the metal filter and a back pressure is applied to the internal combustion engine. Therefore, the amount of the soot trapped in the metal filter is detected. The filter is heated to burn off the soot. (This is called regeneration of the metal filter.) However, when the capacity of the metal filter is increased in this way, the amount of soot that the metal filter can collect will of course increase, but in proportion to this, the amount of heat to be applied during regeneration of the metal filter is also increased. It is very much. In general, a diesel vehicle uses a natural regeneration device in which an oxidation catalyst such as platinum oxidizes NO in exhaust gas to NO 2 and then burns the soot trapped in the filter. Minimum temperature conditions should be provided. In recent years, in order to alleviate the restriction on the temperature condition of the exhaust gas, the diesel fuel is ignited to ignite the exhaust gas by raising the temperature of the exhaust gas to burn the soot or by heating with electricity supplied from the battery of the vehicle. There is a need for a forced regenerative device that additionally supplies the heat required for combustion of the soot, but there is a limit to the amount of heat that can be obtained in this process. However, when the volume of the metal filter is increased in this way, since the amount of heat required for one regeneration is very large, there is a problem that sufficient regeneration cannot be performed by the above-described method. In addition, there is also a problem that the state of the vehicle becomes unstable, such as significantly reduced fuel consumption or greatly reduced the amount of charge of the battery during the regeneration process.

Accordingly, the present invention has been made to solve the problems of the prior art as described above, the object of the present invention is a combination of a plurality of polishing beds in addition to the oxidation catalyst device, a metal filter so that smoke is reduced step by step, The present invention provides a more efficient exhaust gas purification apparatus of a multi-stage reduction method capable of increasing the total smoke reduction performance while reducing the amount of soot, that is, the load of each portion, to be reduced in each portion.

Another object of the present invention is that the size of each part constituting the exhaust purification apparatus can be freely adjusted in accordance with the required performance, and also can be utilized in the passage space, etc. necessary to install in the vehicle while increasing the performance It is an object of the present invention to provide an exhaust purification apparatus of a multistage reduction method that hardly increases space.

Exhaust purification apparatus of the present invention for achieving the above object is harmful in the exhaust gas containing CO, THC, NOx, SOF in the exhaust purification apparatus inserted into the exhaust passage of the diesel engine, using a catalytic reaction. An oxidation catalyst apparatus 100 for removing a portion of the substance; A metal filter 200 for removing some of the harmful substances in the exhaust gas including the soot; And a polishing bed 300 for removing some of the harmful substances in the exhaust gas passing through the metal filter 200. It is made, including, the oxidation catalyst device 100, the metal filter 200 and the polishing bed 300 is characterized in that disposed sequentially from upstream with respect to the flow of the exhaust gas.

At this time, the volume ratio of the oxidation catalyst device 100, the metal filter 200 and the polishing bed 300 is characterized in that in the range of 1: 1: 0.1 to 1: 3: 3:

In addition, a static mixer which equalizes the distribution ratio of harmful substances with respect to the cross section of the exhaust purification apparatus by forming and mixing turbulence in the flow of exhaust gas between the oxidation catalyst apparatus 100 and the metal filter 200. , 400 is further provided.

In addition, the polishing bed 300 is a structure of a metal sheet, a structure of a metal plate coated with granules, a metal foam (metal foam), ceramic foam (ceramic foam), metal fiber (metal fiber), ceramic fiber (ceramic fiber) , Characterized in that formed of any one or more materials selected from sintered metal or wire mesh.

In addition, the polishing bed is characterized in that the removal efficiency of particulate matter per unit volume is equal to or greater than that of the metal filter at the front end.

In addition, the polishing bed 300 is characterized in that provided with at least one. In this case, the oxidation catalyst device 100, the metal filter 200, and the at least one polishing bed 300 are each accommodated in the case 500, and the front end of the case 500 has another case ( The coupling part 510 is formed to be fitted to the rear end of the 500.

In addition, the polishing bed 300 is provided in the exhaust passage of the diesel engine is provided in the connection portion 30 that connects the exhaust purification apparatus accommodating portion 610 and the exhaust pipe 620 in the space provided with the exhaust purification apparatus. It is characterized by.

In addition, the polishing bed 300 is characterized in that the cylindrical polishing bed (300a) is provided in a form surrounding the metal filter 200 in the circumferential direction of the metal filter (200). At this time, the exhaust purification apparatus is characterized in that it further comprises a separate housing 640 to allow the exhaust gas to pass through the cylindrical polishing bed (300a) after passing through the metal filter (200).

In addition, the metal filter 200 and the polishing bed 300 is characterized in that the granular coating (granular coating). At this time, the density of the granules coated on the metal filter 200 is characterized in that the same or relatively lower than the density of the granules coated on the polishing bed 300. In addition, the ratio of the density of the granules coated on the metal filter 200: the density of the granules coated on the polishing bed 300 is preferably in the range of 1: 1 to 1: 3, more preferably, The density of the granules coated on the metal filter 200 is 50 to 100% of the density of the granules coated on the polishing bed 300.

As described above, according to the present invention, the smoke is reduced step by step by using an oxidation catalyst device, a metal filter and a plurality of polishing beds, whereas the smoke is reduced by using the oxidation catalyst device and a single metal filter. By doing so, only a part of the total harmful substance is removed from each part, and the overall performance can be increased while reducing the load on each part.

The present invention also solves the problem of increasing the performance per unit volume of the filter, in particular with respect to the metal filter, since only a single metal filter having a single structure has been used. Simply provided has a great effect of increasing the performance of the exhaust purification apparatus as desired. In addition, in the related art, since the total volume of the metal filter has been increased to increase the performance, it is very difficult to provide an exhaust purifying apparatus having improved performance in an existing vehicle, but it is possible to utilize a passage part of the space where the exhaust purifying apparatus is provided. Therefore, there is a great effect that can increase the performance without requiring more space in the vehicle.

In addition, according to the present invention, since the smoke is reduced in stages, regeneration can be performed independently for the metal filter and each polishing bed, and thus, the amount of heat required for one regeneration is greatly reduced, and the load for obtaining heat is greatly reduced. There is. Therefore, there is also an effect that can keep the vehicle state more stable. Of course, there is also a great effect that each part can be completely regenerated within the range of calories obtained from the vehicle.

Hereinafter, a multistage reduction type exhaust purification apparatus according to the present invention having the configuration as described above will be described in detail with reference to the accompanying drawings.

(Example 1)

2 is a system diagram of a first embodiment of an exhaust purification apparatus according to the present invention. As shown in the figure, the exhaust purification apparatus of the present invention is arranged with an oxidation catalyst apparatus 100, a metal filter 200, and a polishing bed 300 sequentially with respect to the exhaust flow.

The oxidation catalyst device 100 is the same as the oxidation catalyst device 100 'used in the conventional exhaust purification device. The oxidation catalyst device 100 is made into a harmless material by decomposing harmful substances such as CO, THC, NOx, SOF, and the like by using a catalytic reaction and then discharged. Be sure to As the catalyst support used in the construction of the oxidation catalyst device, a ceramic honeycomb may be used, but a metal catalyst support made by folding or rolling a metal thin plate may be used.

The metal filter 200 is also the same as the metal filter 200 'used in the conventional exhaust purification apparatus, and is made by folding or rolling a metal plate having a generally wavy shape as shown in FIG. The soot is filtered and removed by the shape of the metal filter 200 while passing through the 200. By applying a catalyst to the metal plate forming the inside of the metal filter 200, in addition to the soot, harmful substances that are not completely removed from the oxidation catalyst device 100 may be decomposed.

The polishing bed 300 is also a part that plays a role similar to a metal filter. The polishing bed 300 may be made of various materials, that is, the structure of the metal sheet, the structure of the metal plate coated with granules, the metal foam (metal foam), ceramic foam (ceramic foam), metal fiber (metal fiber) , Ceramic fibers, sintered metal, wire mesh, or the like.

Of course, the oxidation catalyst device 100 may also partially remove the soot by the shape thereof, and may also be removed by the decomposition of harmful substances by applying a catalyst to the metal filter 200 and the polishing bed 300. However, the main function of each device is to remove harmful substances by the catalytic reaction, that is, decomposition in the case of the oxidation catalyst device 100, and the metal filter 200 and the polishing bed 300 to filter out the soot. Therefore, the following description will focus on each main function.

In the present invention, the oxidation catalyst device 100 to decompose and remove most of the harmful substances such as CO, THC, NOx, SOF by the catalytic reaction, and the soot is the metal filter 200 and the polishing bed 300 It is shared and removed. When each harmful substance is reduced to 100% while passing through the entire exhaust purification apparatus, each harmful substance in the exhaust purification apparatus of the present invention is reduced in each part as shown in Table 2 below.

Hazardous Substances Oxidation Catalyst Apparatus 100 Metal filter (200) Polishing bed 300 CO, THC 40% to 100% 0% to 40% 0% to 20% NO (→ NO ₂ ) 40% to 100% 0% to 40% 0% to 20% PM SOF 40% to 100% 0% to 40% 0% to 20% Soot 0% to 50% 50% to 90% 10% to 50%

As such, the metal filter 200 and the polishing bed 300 share and remove the soot step by step, thereby reducing the amount of soot, that is, the load on each part, that must be removed from each part. Therefore, the metal filter 200 and the polishing bed 300 may be independently reproduced. However, as described above, since a large amount of heat is required in a short time to regenerate the metal filter, that is, to burn and remove the soot trapped in the metal filter, the waste of fuel is increased or the battery charge is greatly reduced. There was a problem. However, in the present invention, since the metal filter 200 and the polishing bed 300 divide and remove the soot in stages, the volume of each of the metal filter 200 and the polishing bed 300 is conventionally used. Compared to the volume of the metal filter is relatively much smaller, the amount of heat required for regeneration is also significantly reduced.

Meanwhile, as shown in Table 2, the metal filter 200 collects up to 90% of the soot, and the polishing bed 300 collects up to 50% of the soot, so that the metal filter 200 first saturates. Easy to be Therefore, the number of regenerations of the metal filter 200 and the number of regenerations of the polishing bed 300 may not be equal, and the number of regenerations of the metal filter: the number of regenerations of the polishing bed may be adjusted, for example, about 2 to 3: 1. . In the case of the conventional metal filter 200 ', that is, the metal filter 200' provided by itself, the front end has a large amount of soot collection, while the rear end (because the exhaust already filtered through the front end passes). Since the soot collection amount is small, even if the front end is saturated, the rear end can capture the soot even more, but since the front end is saturated, the waste of calories is more severe because the entire metal filter 200 'has to be regenerated. There was a tendency. However, according to the present invention, as described above, since the metal filter 200 on the upstream side of the exhaust gas flow and the polishing bed 300 on the downstream side can be independently regenerated, the amount of heat used for regeneration can be greatly saved. It becomes possible.

In addition, in the present invention, by setting the characteristics of the metal filter 200 and the polishing bed 300 differently, it is possible to further optimize the regeneration ability and the collection capability.

First, in the regeneration capacity, as described above, the collected soot is burned and removed by high heat, so that the temperature is easily increased or the heat capacity is high. If the temperature rises quickly, heat applied from the outside is easily transferred to the inside, and regeneration occurs effectively. If the heat capacity is high, the regeneration may occur continuously while maintaining a high temperature for a long time even after heating once. However, the higher the thermal conductivity and the thinner the material is, the better the temperature rises, while the lower the thermal conductivity and the thicker the material, the better the heat capacity. It was almost impossible to achieve both these high temperatures and high heat capacities in one part.

However, in the present invention, since the metal filter 200 is disposed at the front end and the polishing bed 300 at the rear end as independent parts, it is possible to design the parts independently so as to have characteristics that can be optimized more. Do. That is, the metal filter 200 is made of a thin plate so that the temperature rises much better when heating, and the polishing bed 300 is made of a thick material to increase the heat capacity. In particular, the polishing bed 300 may be made of a ceramic as well as a metal as described above, it is possible to further increase the heat capacity.

In addition, in the trapping capability, as described above, since the trapping has already taken place at the front end and the exhaust gas is removed at the rear end side of the exhaust purification apparatus, a conventional metal filter having the same characteristics as the front end and the rear end ( In the case of 200 '), the collection occurred inefficiently. However, in the present invention, a metal filter 200 capable of filtering a soot having a relatively large particle size is disposed on the upstream side of the exhaust, and on the downstream side (since the soot has already been filtered out of the metal filter 200), Since only soot having a small particle size is left), the capturing ability may be optimized by disposing a polishing bed 300 made of a material such as foam or fiber, which may filter finer soot. Of course, the overall collection capacity of the exhaust purification apparatus also increases accordingly.

The volume ratio of each component in the present invention optimizes the collection capacity by keeping the oxidation catalyst device 100: metal filter 200: polishing bed 300 in the range of 1: 1: 0.1 to 1: 3: 3. .

In addition, it is preferable that the metal filter 200 and the polishing bed 300 have a granular coating on the surface in order to increase the collection capability of the soot. At this time, as described above, the metal filter 200 collects particles having a relatively large particle size, and the polishing bed 300 collects particles having a relatively small particle size, and thus a polishing bed for collecting finer particles. It is advantageous to coat the granules densely on the 300 side. In the present invention, the ratio of the density of the granules coated on the metal filter 200: the density of the granules coated on the polishing bed 300 is optimized in the range of 1: 1 to 1: 3. That is, the density of the granules coated on the metal filter 200 is preferably 50 to 100% of the density of the granules coated on the polishing bed 300.

(Example 2)

3 is a system diagram of a second embodiment of the exhaust purification apparatus of the present invention. In the second embodiment, a static mixer 400 is provided between the oxidation catalyst device 100 and the metal filter 200. The static mixer 400 forms a turbulent flow in the flow of the exhaust gas passing through the oxidation catalyst device 100 and mixes it to equalize the distribution ratio of harmful substances with respect to the cross section of the exhaust purification device. Exhaust gas can be supplied evenly to the cross section of the metal filter 200 by the static mixer 400. Therefore, in the metal filter 200, a part of the cross section of the metal filter 200 is provided. Suits can be collected evenly, with or without the suits concentrated.

(Example 3)

4 is a system diagram of a third embodiment of the exhaust purification apparatus of the present invention. The oxidation catalyst device 100, the metal filter 200 and the polishing bed 300 are integrated in other embodiments, ie in one housing to form an exhaust purification device, while in the third embodiment Each is accommodated in an independent case 500, the case 500 is combined with each other to form an exhaust purification apparatus. As shown, the front end portion of the case 500 is provided with a coupling portion 510, so that it can be fitted to the rear end of the other case 500. Of course, the coupling part 510 is further preferably provided with a padding 520 to prevent the exhaust gas from leaking.

In addition, as shown in FIG. 4, the polishing bed 300 may be provided in plural, not just one. In particular, as shown in the embodiment of FIG. 4, when each component is accommodated in an independent case 500 to be combined to form an exhaust purification apparatus, the case 500 containing the polishing bed 300 is further coupled to a rear end portion. The configuration is easy because it only needs to be done.

(Example 4)

5 is a system diagram of a fourth embodiment of the exhaust purification apparatus of the present invention. In other embodiments, the exhaust purification apparatus is provided only on the exhaust purification apparatus accommodating portion 610, but in the fourth embodiment, the oxidation catalyst apparatus 100 and the metal filter 200 may be disposed in the exhaust purification apparatus accommodating portion ( 610 is provided in the interior, and the polishing bed 300 is provided in the connecting portion 630 in the shape of a truncated cone connecting the exhaust purification apparatus accommodating portion 610 and the exhaust pipe 620. Since the connecting portion 630 has a truncated cone shape, the polishing bed 300 may be formed in a truncated cone shape as shown in FIG. 6 (A), or as shown in FIG. 6 (B). Combining a plurality of them, each of the polishing bed 300 is a flat cylindrical shape and may be formed to be easily provided in the connecting portion 630 of the truncated conical shape.

On the other hand, in the case of the metal filter 200, as shown in Figure 8 because it is made by folding or winding the thin plate it is impossible to make a truncated cone at all. However, as described above, the polishing bed 300 may be made of a material such as a ceramic as well as a metal. In particular, even the metal is not made by folding or winding a thin plate like the metal filter 200, but a metal foam or a metal fiber. It is made of the same material. Therefore, the polishing bed 300 is much easier to make the shape desired by the user. Therefore, it can be easily made in the shape of a truncated cone that fits snugly in a truncated cone-like space such as the connecting portion 630. In the case of the conventional metal filter 200 ′, the connection portion 630 could not be used at all, but according to the present invention, the polishing bed 300 may be further provided by utilizing the connection portion 630. . As a result, it is natural that the exhaust purification capability can be further improved without changing the volume of the exhaust purification apparatus accommodating part 610.

In FIG. 5, the static mixer 400 is provided between the oxidation catalyst device 100 and the metal filter 200. Of course, the static mixer 400 may not be provided.

(Example 5)

7 is a system diagram of a fifth embodiment of the exhaust purification apparatus of the present invention. In this case, the polishing bed 300a is provided to surround the metal filter 200 in the circumferential direction of the metal filter 200. As described above, the polishing bed 300a may be manufactured in an annular type in this way because it is easy to make a shape as desired by the user. Of course, in this case, it is preferable that a separate housing 640 is further provided to allow the exhaust gas to flow toward the columnar polishing bed 300a after passing through the metal filter 200.

Although the cylindrical polishing bed 300a is thin in thickness, the cross-sectional area is wide, so that it is possible to effectively remove harmful substances.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It goes without saying that various modifications can be made.

1 is a system diagram of an exhaust purification apparatus according to the prior art.

2 is a system diagram of a first embodiment of an exhaust purification apparatus according to the present invention;

3 is a system diagram of a second embodiment of an exhaust purification apparatus according to the present invention;

4 is a system diagram of a third embodiment of an exhaust purification apparatus according to the present invention.

5 is a system diagram of a fourth embodiment of an exhaust purification apparatus according to the present invention.

Fig. 6 is a detailed configuration diagram of the polishing bed of the fourth embodiment of the exhaust purification apparatus according to the present invention.

7 is a system diagram of a fifth embodiment of the exhaust purification apparatus according to the present invention.

8 is a perspective view of a metal filter;

DESCRIPTION OF REFERENCE NUMERALS

100: oxidation catalyst device 200: metal filter

300: polishing bed 400: static mixer

500: case 510: coupling part

520: padding

610: exhaust purification apparatus accommodating part 620: exhaust pipe

630: connection

Claims (13)

In the exhaust purification apparatus inserted into the exhaust passage of a diesel engine, An oxidation catalyst apparatus 100 for removing a part of harmful substances in exhaust gas including CO, THC, NOx, SOF using a catalytic reaction; A metal filter 200 for removing some of the harmful substances in the exhaust gas including the soot; And Metal sheet structure, granule coated metal sheet structure, metal foam, ceramic foam, ceramic fiber, metal fiber, ceramic fiber, sintered metal or wire A polishing bed 300 formed of at least one material selected from a wire mesh to remove a part of harmful substances in the exhaust gas passing through the metal filter 200; The oxidation catalyst device 100, the metal filter 200 and the polishing bed 300 is a multi-stage reduction method characterized in that disposed sequentially from upstream with respect to the flow of the exhaust gas. Exhaust purifier. The volume ratio of the oxidation catalyst device 100, the metal filter 200 and the polishing bed 300 is The exhaust purification apparatus of the multistage reduction system characterized by being in the range of 1: 1: 0.1-1: 3: 3. The method according to claim 1, A static mixer 400 which equalizes the distribution ratio of harmful substances with respect to the cross section of the exhaust purification apparatus by forming and mixing turbulence in the flow of exhaust gas between the oxidation catalyst apparatus 100 and the metal filter 200. The exhaust purification apparatus of the multistage reduction system characterized by the above-mentioned. delete The method of claim 1, wherein the polishing bed 300 At least one or more exhaust purification apparatus of the multistage reduction system characterized by the above-mentioned. 6. The method of claim 5, The oxidation catalyst device 100, the metal filter 200, and the at least one polishing bed 300 are each accommodated in a case 500. Multi-stage reduction type exhaust purification apparatus, characterized in that the front end portion of the case 500, the coupling portion 510 is formed to be fitted to the rear end of the other case 500. The method of claim 1, wherein the polishing bed 300 Multi-stage reduction method, characterized in that formed in the exhaust passage of the diesel engine is provided in the connecting portion 30 that connects the exhaust purification apparatus accommodating portion 610 and the exhaust pipe 620 in the space provided with the exhaust purification apparatus. Exhaust purifier. The method of claim 1, wherein the polishing bed 300 Multi-stage reduction type exhaust purification apparatus, characterized in that the cylindrical polishing bed (300a) provided in the form of surrounding the metal filter (200) in the circumferential direction of the metal filter (200). The method of claim 8, wherein the exhaust purification apparatus And a separate housing (640) for allowing exhaust gas to pass through the cylindrical polishing bed (300a) after passing through the metal filter (200). The method of claim 1, wherein the metal filter 200 and the polishing bed 300 A multistage reduction type exhaust purification apparatus characterized by having a granular coating. The method of claim 10, Multi-stage reduction type exhaust purification apparatus, characterized in that the density of the granules coated on the metal filter 200 is equal to or less than the density of the granules coated on the polishing bed (300). 12. The method of claim 11, Density of the granules coated on the metal filter 200: The ratio of the density of the granules coated on the polishing bed 300 is in the range of 1: 1 to 1: 3 exhaust reduction apparatus of the multi-stage reduction method. . 13. The method of claim 12, The density of the granules coated on the metal filter 200 is 50 ~ 100% of the density of the granules coated on the polishing bed 300, the exhaust purification apparatus of the multi-stage reduction method.

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