DE2953010T1 - DEVICE FOR PURIFYING EXHAUST GAS OF DIESEL ENGINE - Google Patents

Description

-a-

Emission control system for diesel engines

The invention relates to an exhaust gas cleaning system for diesel engines.

The field of application of the invention is that of exhaust gas cleaning systems for Diesel engines or diesel engines that are used together with construction site equipment or in simple vehicles such as diesel buses and diesel vehicles or are installed in buildings for operating various systems and devices.

So far, various exhaust gas cleaning systems have been used for diesel engines proposed and used. Typical examples are:

a) a system that is a combination of a smoke removal device such as a cyclone with a catalyst bed arranged in the exhaust line for the exhaust gas discharged from the diesel engine, and

b) a system in which the exhaust gas is blown into water or a System comprising a combination of a scrubber type smoke removal device which atomizes wash water and feeds it into the Injected exhaust gas, and having a catalyst bed.

Dust-collecting facilities that function according to the principle of inertia, however, such as cyclones used in the above-mentioned system (a) are only effective on dust particles of particle sizes of more than several micrometers. They cannot be used to effectively collect smoke particles with smaller particle sizes. In general, the smoke particles in the exhaust gases emitted by diesel engines are too small to be removed from collection devices after function according to the principle of inertia, to be caught. Hence is

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It is not possible to remove the smoke particles from the exhaust gas from diesel engines to be collected in an expedient manner with cyclones. As a result, the carbon particles from the smoke will adhere during prolonged periods of operation disadvantageously stuck to the surface of the catalyst, thereby impairing the function of the catalyst and making it no longer possible will effectively remove the offensive odor and harmful components such as carbon monoxide and hydrocarbons. To the '.. Regeneration of the catalyst requires heating it to a high temperature. This is not only troublesome, it is caused also an impairment of the catalytic function, as well as a Deformation or breakage of the catalyst material.

In the conventional system (b) mentioned above, with the scrubber-type smoke removal device effectively removes smoke. However, as a result of the supply of water, one occurs large amount of water vapor, which is a disturbing visual obstruction in the area. Furthermore, troublesome maintenance work such as Renewal of the washing water supply, etc. required.

For a complete removal of the bad smell and harmful ones Components of the exhaust gas, it is necessary that the exhaust gas has a high temperature between 300 and 500 C at the catalyst inlet. In the above-mentioned system (b), however, the exhaust gas temperature becomes inappropriately reduced when the exhaust gas with water is washed in the scrubber type smoke removal device. For this reason it is not practical to use the catalyst on the downstream side, d. H. on the outlet side to place the scrubber type smoke removal device. Consequently, it is unavoidable that the smoke particles adhere to the catalyst, thereby giving rise to the various disadvantages that are already known have been mentioned in connection with the usual system (a) above.

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The object of the invention is accordingly to provide an exhaust gas purification system for To provide diesel engines, which has a simple design, requires little maintenance in operation, the smoke particles contained in the exhaust gas safely removed and its high effectiveness in the exhaust gas cleaning retains even in the course of a longer period of operation.

The solution to the problem according to the invention results from the claims. -

In the exhaust gas cleaning system according to the invention, the smoke ponds by one on the upstream side, d. H. refractory arranged at the inlet side of a catalyst system or catalyst bed Filter removed, eliminating the problems mentioned at the beginning of the known Systems are eliminated. Those caught by the heat-resistant filter. Genuine smoke particles are burned with a device of simple construction.

The exhaust gas cleaning system according to the invention for diesel engines contains an exhaust gas cleaning line for cleaning the emitted by the diesel engine Exhaust gas, one at an upstream point of the exhaust gas cleaning line arranged heat-resistant filter, a catalytic converter or a catalyst bed, which is used to remove the malodor and the harmful components of the exhaust gas are formed and arranged at a downstream point of the exhaust gas cleaning line, and a regeneration device, which is connected to the heat-resistant filter and is designed to collect the heat-resistant filter Burn and remove smoke particles.

With this arrangement, the undesirable adherence of the smoke particles becomes obsolete on the catalyst bed effectively prevented by the filter effect of the heat-resistant filter, so that a good cleaning effect in the course of a long service life is guaranteed. At the same time, the heat can be solid Filters collected smoke particles easily through the regeneration

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facility to be burned and removed.

The heat-resistant filter of the above-mentioned improved according to the present invention The cleaning system is designed and composed in such a way that the combustion and removal of the heat-resistant filter Trapped Rpuchteilchen even during the flow of the exhaust gas is feasible through the heat-resistant filter. Consequently, the inventive Emission control system for diesel engines can be designed to be small and compact.

There are thus one or more heat-resistant filters in the invention on the upstream or inlet side of a catalyst bed: arranged, which by their filtering effect those suspended in the exhaust gas. " Catch and remove smoke particles completely, so that an undesirable Adherence of the smoke particles to the catalyst bed is largely avoided. Means are also provided to make the refractory filter simple regenerate by burning the smoke particles captured by the filters. In one embodiment of the invention, a refractory filter and a catalyst bed are in the form of nested and adjoining hollow cylinder. To regenerate the heat-resistant Filter is introduced into the filter by the action of a high pressure burner or a vacuum or negative pressure generating device. In this embodiment, the heat-resistant filter and the catalyst bed are accommodated in a single housing.

The exhaust gas cleaning system according to the invention for diesel engines ensures in the course of a longer period of operation, the removal of smoke particles and harmful components as well as unpleasant smells from the exhaust gas given off by the diesel engine.

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Based on the drawing and the description below, preferred Embodiments of the invention explained in detail. Show it:

Fig. 1 is a schematic diagram of a practicable one Embodiment of the exhaust gas cleaning system according to the invention for diesel engines;

2 shows a longitudinal cross-section through an exhaust gas cleaning device, which represents a further embodiment of the invention;

3 shows a cross section through the embodiment shown in FIG along the line A-A and

4 and 5 are schematic cross-sections through practical configurations the one in Fig. 2 and 3 shown embodiment of the Invention.

1 shows a diesel engine 1 with an exhaust gas cleaning system according to the invention fitted. Two branch lines 3, 4 are connected to the inlet end piece 2 of an exhaust gas cleaning line. In the place at which the branch lines 3 and 4 merge into one another, a switching valve 5 is arranged so that the exhaust gas flow depending on the position of the switching valve 5 can be guided via line 3 or line 4.

Heat-resistant filters 6 and 7 are provided in the branch lines 3 and 4, respectively. The heat-resistant filters 6 and 7 are made of metal fibers with different fiber diameters, the fiber diameters according to FIG the particle size distribution occurring in the area has been selected are. The metal fibers of different fiber diameters are formed into superimposed or laminate-like layers, which in particular

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overall have a generally cylindrical or disk-shaped shape.

Lines 3 and 4 lead to branch lines 3a and 3b and 4a and 4b, respectively. The lines 3a and 4a lead to an exhaust pipe 8, while the lines 3b and 4b lead to a catalytic converter 9, the its outlet side is connected to the exhaust pipe 8. Changeover valves 10 and 11 are on the ones leading to the branch lines 3a, 3b and 4a, 4b, respectively Branches provided. The switching valves 10 and 11 are designed such that either a direct connection between the lines 3 or 4 and the exhaust pipe 8 on the other hand or a connection between the lines 3 or 4 on the one hand and the catalytic converter 9 on the other hand can be produced.

Regeneration lines 12 and 13 extend between the branch lines 3 and 4. The regeneration lines 12 and 13 are with the inlet sides of the heat-resistant filters 6 and 7 connected. There is also a switch valve arranged at an injection opening 14 of the regeneration lines 12 and 13, in front of which a burner 16 is located. With this arrangement, the smoke particles clogging the heat-resistant filters 6 and 7 are burned and removed when hot air is blown into the filters 6 and 7 from the blower 17. The regeneration device thus consists of this arrangement to regenerate the heat-resistant filters 6 and 7. Since the exhaust gas emitted by the diesel engine only contains a small amount of oxygen contains, it is difficult to burn the smoke particles. The fan 17 is thus provided to supply outside air, which is the perfect Combustion of smoke particles supported.

Differential pressure gauges 18 and 18 are attached to the heat-resistant filters 6 and 7. 19 provided. In particular, the differential pressure meter 18 is in Connection with the outlet side and the inlet side of the heat-resistant filter 6, while the differential pressure meter 19 with the outlet side and

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the inlet side of the heat-resistant filter 7 is in communication. These differential pressure gauges are designed to measure the differential pressure or the pressure gradient across the refractory filters 6 and 7, i. H. The constipation this filter with smoke particles to determine.

Although not shown, automatic control is provided, which actuates the switching valves 5, 10, 11 and 15 automatically to control the path of the exhaust gas in a corresponding manner and the burner 16 and to put the fan 17 into operation automatically, whereby. Hot air is introduced into the heat-resistant filters 6 and 7 in order to reduce the in these Burn and remove any smoke particles in the filter. This automatic control takes place depending on the clogging condition the heat-resistant filters 6 and 7 instead, which is detected by the differential pressure gauges 18 and 19.

The function of the exhaust gas cleaning system according to the invention, which has the construction described above is as follows: It is assumed that the diesel engine has been started is, the switching valves 5, 10, 11 and 15 have the positions shown in FIG. The exhaust gas discharged from the diesel engine 1 flows via the inlet end piece 2 into the branch line 3 and then through the refractory filter 6 to the catalytic converter 9 via the branch line 3b. The exhaust gas is finally released to the outside air through the exhaust pipe 8. It should be noted that it is the most heat resistant during the filtering process Filter 6 is possible to collect even relatively small smoke particles with certainty, so that the smoke particles suspended in the exhaust gas completely removed. On the other hand, harmful components of the exhaust gas such as carbon monoxide and hydrocarbons and the bad smell become too converted into harmless carbon dioxide, due to the catalytic oxidation effect of the catalyst located in the catalytic converter 9. In this connection it should be noted that undesired adherence of the smoke particles to the catalytic converter 9

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going is avoided because the smoke particles are already heat-resistant Filter 6 have been collected and removed so that the catalytically ^ Effect of the catalyst over a long period of operation without impairment is maintained.

The deposition of smoke particles in the heat-resistant filter 6 turns out to be an increase in the pressure drop between the inlet and outlet sides of the heat-resistant filter 6 noticeable. This increase is determined in an expedient manner by the differential pressure meter 18, which in turn causes the changeover valves 5, 10, 11 and 15 to switch over automatically, to divert the exhaust gas so that it flows through the branch pipe and to the refractory filter 7. This creates a continuous Cleaning made possible. At the same time, the burner 16 and the fan 17 are automatically put into operation according to the one with the smoke particles clogged heat-resistant filter 6 to supply hot air, whereby the smoke particles captured by the heat-resistant filter 6 are completely burned and the filter is regenerated in a relatively short time.

The gases generated during the regeneration of the refractory filter are Derived directly through the exhaust pipe 8 via the branch line 3.

After the regeneration is complete, the pressure drop between the The inlet side and the outlet side of the heat-resistant filter 6 are reduced. This reduction in pressure is detected by the differential pressure meter 18, which in turn generates a control signal by which the operation of the burner 16 and the fan 17 is suspended.

In this embodiment described, the heat-resistant filters are 6 and 7 are arranged in parallel with each other to allow switching so that the filter in one branch is in operation during the Filter in the other branch is regenerated. However, this arrangement is not the only one that can be used, and it is also possible to

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to make gas cleaning system small and compact that only a pipe containing a heat-resistant filter is used and the exhaust gas is also passed through this filter during the regeneration of this single heat-resistant filter.

A further embodiment of the invention will be described below with reference to FIGS. 2 and 5, in which only one, one heat-resistant Filter having line is used.

A cylindrical hollow housing 21 is located in the exhaust system of a diesel engine. In the wall of the housing 21 at a location close to an axial end of the housing 21 is an inlet opening provided for the exhaust gas, while an outlet opening 23 for the exhaust gas; is formed in the vicinity of the other axial end of the housing 21. In the housing 21, a heat-resistant filter 24 is housed, which of Metal fibers or chemical material formed and formed into a mat or thin layer and helically wound or wound in this way has been that it takes the shape of a hollow cylinder. As with the refractory filter of the first embodiment, this is refractory Filter 24 of the second embodiment made of metal fibers with different fiber diameters, which correspond to the particle size distribution the smoke particles have been selected.

The axial end, which is closer to the inlet opening 22, of the cylindrical, Heat-resistant filter 24 is closed by a cover 25, while the other, closer to the outlet opening 23, the end of the hollow cylindrical The filter is open and in communication with the outlet port 23.

A catalyst bed 26 is also accommodated in the housing 21. This Catalyst bed 26 contains a sponge-like η metal catalyst, the Wound or wound into a hollow cylindrical shape is. Typically, the metal catalyst consists of platinum or similar

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Lichem material, which to remove the bad smell and the harmful components of the exhaust gas, e.g. B. carbon monoxide and hydrocarbon is suitable. _The catalyst bed 26 is inside of the hollow cylindrical, heat-resistant filter 24, d. H. at the downstream located side or the outlet side of the filter 24 and is thus under the heat-resistant filter 24.

A partition plate 27 is near the outlet port 23 of the housing 21 provided and formed around the inlet port. 22 and the outlet opening 23 of the housing 21 to be separated from each other. Hence, that achieves Exhaust gas flowing into the housing 21 through the inlet opening 22 is the outlet opening 23 only over the cylindrical circumferential surfaces of the heat-resistant filter 24 and the catalyst bed 26.

A high pressure burner 28 is airtight with one axial end of the housing 21 connected, which is closer to the inlet port 22. This high pressure burner 28 is a function of the differential pressure on both sides the laminate layers of the refractory filter 24 and the catalyst bed 26 or the differential pressure between the inlet port 22 and the outlet port 23 of the housing 21, i.e. H. depending on the state of constipation of the heat-resistant filter 24, which is detected by a differential pressure meter (not shown), operable. Because of the level of pressure that the high-pressure burner 28 can withstand during operation, it is possible to use the high-pressure burner 28 while it is running of the diesel engine, d. H. when the exhaust gas flows through the heat-resistant filter 23 to operate. As a result, the burner 28 can also be used with Supply exhaust gas to the heat-resistant filter 24 with hot air in order to regenerate the heat-resistant filter 24.

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In the high pressure burner 28 is an inlet opening 29 for high pressure combustion air intended. The high-pressure burner 28 has means that ensure its function even when the pressure of the in the Housing 21 introduced exhaust gas fluctuations occur. On the high pressure burner 28 there is a cylindrical, heat-radiating plate 30 which surrounds the flame formed by the high-pressure burner 28. In near the free end of the cylindrical heat radiating plate 30 are distributed a plurality of holes on the circumference thereof 30a. The housing 21 has a heat-insulating material 31 on its inside and a fastening device on its outside: device 32 for mounting the housing 21 on.

FIGS. 4 and 5 show a further development of this second embodiment. In the described second embodiment, which has only one heat-resistant filter, the device is for regeneration of the heat-resistant filter 24 from the high-pressure burner 28. In this case In a further refinement of this embodiment, however, the high-pressure burner 28 is replaced by the combination of a simple low-pressure burner with a vacuum or negative pressure generating device, which is located within the exhaust pipe. That is, the low pressure burner and the vacuum or negative pressure generating device forms the regeneration device for the heat-resistant filter 24. The vacuum or The vacuum generating device 33 is located in the exhaust pipe 34 on the inlet side of the housing 21. The device 33 can thereby provide that the diameter of the exhaust pipe 34 is locally reduced, as shown in FIG. 4, or that the exhaust pipe 34 is separated into two parts is, the diameters of the opposite parts of the exhaust pipe 34 are different, as shown in FIG. 5, so that one part acts as a nozzle from which the exhaust gas flows into the other part of the line. In both cases, one occurs in the vacuum or negative pressure generating device 33 laterally opening tube 36 a suction effect. The low pressure burner 35 is at the other end of the tube

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arranged so that the hot air generated by the low pressure burner 35 sucked into the vacuum or negative pressure generating device 33 and reaches the housing 21 together with the exhaust gas flowing through.

The exhaust gas cleaning system of the construction described above works as follows: When the diesel engine is running, this is from ^ = given exhaust gas is introduced into the housing 21 through the inlet port 22 and flows through the walls of the refractory filter 21 and the catalyst bed 26. Finally, the exhaust gas is discharged through the outlet opening 23. The smoke particles suspended in the exhaust gas are all caught by the heat-resistant filter 24 from the exhaust gas flowing through. Furthermore will the bad smell and the harmful components such as carbon monoxide and hydrocarbons due to the catalytic effect of the exhaust gas: through-flow catalyst bed 26 effectively removed.

Because the smoke particles of the exhaust gas through the filtering effect of the heat-resistant Filters 20 are completely caught and removed, it should be noted that that undesired adherence of the smoke particles to the catalyst bed 26 is largely avoided, whereby a good catalytic Effect of the catalyst guaranteed over a long period of operation is.

As the amount of those collected by the heat-resistant filter 24 increases Smoke particles will be the differential pressure between the inlet port 22 of the housing 21 and the outlet port 23 of the housing 21 accordingly enlarged. This increase in differential pressure is detected by a differential pressure meter (not shown). When reaching a given Differential pressure sets the differential pressure meter the high pressure burner 28 in operation. This causes hot air to enter the housing 21 introduced so that the smoke particles caught by the refractory filter 24 are completely burned and removed, and the refractory filter

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24 is thus regenerated. This in turn causes the Differential pressure in the housing 21, the detection of which leads to the high-pressure burner 28 being put out of operation. When operating the high pressure burner 28, the heat radiating plate 30 is heated to red heat. The exhaust gas introduced through the inlet port 22 is against the Circumferential surface of the end portion of the heat radiating plate 30 is blown and heated by this while it is the cylindrical peripheral surface of the heat radiating plate 30 flows around helically. This heated Gas then flows through the refractory filter 24 to completely remove the smoke particles to burn and remove.

Similarly, in the system shown in Figs the clogging of the filter is detected by a differential pressure meter (not shown) and the low-pressure burner 35 is put into operation. The hot air generated by the low-pressure burner 35 is due to the negative pressure generated by the vacuum or negative pressure generating device is generated, sucked and introduced into the housing 21, wodurdi the smoke particles caught by the heat-resistant filter 24 are completely burned and removed.

The invention thus provides a small size system for cleaning the exhaust gas emitted by a diesel engine. This system, which has high cleaning efficiency and is easy to maintain, can be used in various diesel engines, e.g. B. in those mounted on construction equipment or in simple vehicles such as diesel buses and diesel trucks are built in, or those that are installed in buildings.

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Claims (9)

Patent attorneys
8000 Munich 22 · Steinsdorfstrasse 21-22 ■ Telephone 089/22 94 41 SHIMIZU CONSTRUCTION CO., LTD. 16-1, Kypbashi 2-chome, Chup-ku, Tokyo 104, Japan Emission control system for diesel engines Patent claims: nJ exhaust gas cleaning system for diesel engines, marked through an exhaust gas cleaning line (2, 3 or · .2,4) into which the a diesel engine (1) given exhaust gas is introduced, a heat-resistant filter (6 or 7) at an upstream point of the exhaust gas cleaning line (2, 3 or 2, 4) provided and for collecting and Removal of the suspended smoke particles contained in the exhaust gas is formed, a catalytic converter (9) attached to a downstream lying point of the exhaust gas cleaning line (2, 3 or 2, 4) and for removing bad smells and harmful components of the Exhaust gas is formed, and a with the heat-resistant filter (6 or 7) connected regeneration device (16, 17) for burning and removing the smoke particles captured by the heat-resistant filter (6 or 7) are formed (Fig. 1). 130611/0010 9569 - J / Li 2. Exhaust gas cleaning system according to claim 1, characterized in that that the heat-resistant filter (6 or 7) contains a combination of metal fibers with different fiber diameters. 3. Exhaust gas cleaning system according to claim 1 or 2, characterized in that that the exhaust gas cleaning line (2, 3 or 2, 4) is composed of a plurality of branch lines, each one heat-resistant Filter (6 or 7) have, and that a switch valve (5) is provided at the branching point of the branch lines, with which the Exhaust gas can be directed into a selected branch line. 4. Exhaust gas purifying system according to claim 3, characterized _marked: '_": characterized in that each of the heat-resistant filter (6 or 7) with a differential rentialdruckmesser provided (18 and 19), with which the at respective filter (6 or . 7) lying differential pressure can be determined, and that means are provided for automatically controlling the switching of the switching valve (5) and the function of the Re generating device (16, 17) as a function of the differential pressures determined with the differential pressure gauges (18 or 19) . 5. Exhaust gas cleaning system for diesel engines, characterized by an exhaust gas cleaning line in which the emitted by a diesel engine ne Exhaust gas is introduced, a heat-resistant filter (24) which is arranged in the exhaust gas cleaning line and which is used to collect and remove smoke particles is formed, a on the downstream side of the heat-resistant filter (24) arranged catalyst bed (26), one with the Heat-resistant filter (24) connected regeneration device, which is used to burn and remove the collected by the heat-resistant filter (24) Smoke particles is formed, a provided in the exhaust gas cleaning line, single housing (21), which the heat-resistant filter (24) and the catalyst bed (26) contains and means that operate the regenerator allow during the emission of the exhaust gas (Fig. 2-5). 9569 130611/0010 • JV- -JS- 6. exhaust gas purification system according to claim 5, characterized in that the heat-resistant filter (24) contained in the housing (21) has a hollow cylindrical shape and is designed such that the Exhaust gas flows through the cylindrical peripheral surface of the heat-resistant filter (24). 7. exhaust gas purification system according to claim 6, characterized in that the catalyst bed (26) contained in the housing (21) has a hollow cylindrical shape and is arranged together with the hollow cylindrical filter (24) in the form of a laminate. 8. Exhaust gas cleaning system according to one of claims 5, 6 or 7, there: characterized in that the regeneration device for the: heat-resistant filter (24) consists of an airtight attached to the housing (21) There is a high pressure burner (28). 9. exhaust gas purification system according to one of claims 5, 6 or 7> characterized in that the regeneration device for the heat-resistant filter (24) consists of a combination of one in the exhaust pipe upstream of the housing (21) provided vacuum-generating device (33) and one on the vacuum-generating device (33) There is a low pressure burner (35) (Figs. 4 and 5). 130611/0010 9569