IE911807A1

IE911807A1 - An exhaust gas removal system

Info

Publication number: IE911807A1
Application number: IE180791A
Authority: IE
Original assignee: Zeuna Staerker Kg
Priority date: 1990-06-27
Filing date: 1991-05-27
Publication date: 1992-01-01
Also published as: HU911989D0; PT98094A; MC2268A1; NO912515L; FI912928A; FI912928A0; NO912515D0; EP0463361A1; DE4020357A1; HUT60016A; CS196791A3; BG94705A

Abstract

In an exhaust gas conduit (10) having a device (13, 14) for purifying the exhaust gases, the arrangement of a cooling device (16) for the purified exhaust gases (17) is proposed. The cooling device is arranged in the exhaust gas line (12) in a suitable region downstream from the purification device (13, 14) in the flow direction. A heat exchanger (16) or a mixing device can be provided as the cooling device, by means of which cool environmental air can be supplied to the hot exhaust gases. In consequence, damage resulting from overheating, especially in the outlet region of the exhaust gases, is avoided.

Description

An Exhaust Gas Removal System.

The invention relates to an exhaust gas removal system and more particularly but not exclusively to such a system which comprises an exhaust gas duct and a device which is intermediately placed in the exhaust gas duct and is adapted to increase the exhaust gas temperature in order to clean the exhaust gas.

Numerous known exhaust gas cleaning systems (such as post-combustion devices, catalytic converters, filters for suspended particles, and the like) involve heating the exhaust gas in order to perform the desired reaction such as oxidation. The removal of the exhaust gas heated in this manner and more particularly the emergence of the exhaust gas from the exhaust gas removal system involve a hazard which may lead to injury to humans and damage to equipment.

One object of the invention is provide an exhaust gas removal system of the type initially mentioned, in the case of which there is no risk of injury or damage owing to the exhaust gas.

In order to achieve this or other objects the present invention provides an exhaust gas removal system comprising an exhaust gas removal duct in which a device for cleaning the exhaust gas is intermediately placed, characterized in that a device for cooling the exhaust gas is functionally associated with the exhaust gas duct for cooling the exhaust gas downstream from the cleaning device.

In the apparatus in accordance with the invention the - 2 excess thermal energy is abstracted from the exhaust gas after the reaction or cleaning of the exhaust gas so that more particularly in the case of overheating of the exhaust gas during the cleaning process no hazard involving danger or injury is likely. This means that with a comparatively small amount of effort and complexity in many cases it is possible to reduce the temperature of the exhaust gas to such an extent that furthermore it is possible to do without thermal insulation on adjacent parts of the system.

In accordance with one possible embodiment of the invention 10 a heat exchanger is provided in the exhaust gas duct downstream from the exhaust gas cleaning device, the cooling medium of the heat exchanger being for instance air from the environment, compressed air supplied through a separate system or a liquid. The last mentioned possibility is to be preferred if the thermal energy may is to be utilized for some other purpose.

The function of a heat exchanger may alternatively be performed by the design of the exhaust gas duct so that it has a larger contact surface between the exhaust gas and the cooling medium.

In accordance with one possible effective modification of the invention for cooling the exhaust gas there is a dilution of the hot exhaust gas with cooling air more particularly air from the environment.

The supply of the into the exhaust gas duct may be forced, that is to say using a blower or a compressor or the air charger of an internal combustion engine. Such a system may for instance be operated with a temperature control means.

In accordance with a still further possible embodiment of the invention the exhaust gas duct is designed with internal structures adapted to cause an aerodynamic action and which while producing a pressure differential and utilizing the exhaust gas flow make possible the supply of air from the environment into the exhaust gas duct. This design is simple to produce, in which the exhaust gas duct is provided with inlet openings for the air from the surroundings, which openings are so designed that the flowing exhaust gas draws in air through the openings from the surrounding ai r.

The cooling of the exhaust gas may be performed in any convenient part of the exhaust gas removal system, in which the cleaned exhaust gas flows. The arrangement selected will be in accordance with the specific application, the amount of space available and the desired effect. The cooling part may be arranged directly following the zone downstream from the cleaning device if the reactions between the components of the exhaust gas are already completed here. If space is at a premium it is best to have an arrangement in which the cooling device is placed at the outlet end of the exhaust gas duct.

The invention will now be described in the following with reference to the diagrammatically illustrated embodiments appearing in the accompanying figures Figure 1 shows an exhaust gas removal system in accordance with a first working embodiment of the invention in the form of a cooling device.

F i g u re 2 to Figure 4 respectively show one further embodiment of the invention.

Figure 5a and Figure 5b respectively a longitudinal and cross section of a further embodiment of the invention.

Figure 1 shows an exhaust gas removal system 10 of an internal combustion engine 11, which comprises an exhaust gas duct 12 in which there is an intermediate filter for suspended solid particles 13. The particle filter 13 is associated with a regenerating burner 14 from which the hot gases are passed into the exhaust gas duct 12 at a point which is upstream from the particle filter.

In the case of an exhaust gas of this type or in the case of other exhaust gas cleaning methods, as for instance involving post-combustion, catalytic converters and the like, there may be an overheating of the exhaust gas 17 if the regulating system should fail. The consequence of this may be that persons or components in the neighborhood of the exhaust gas duct 12 and more particularly at the outlet end thereof are injured or, respectively, damaged by the hot exhaust gas 17. In order to avoid such hazard a cooling device 16 is provided for thermal cooperation with the exhaust gas 12 downstream from the cleaning device 13 and 14.

In the design in accordance with figure 1 the cooling device 16 consists of a heat exchanger of any suitable form, in the case of which the thermal energy from the hot exhaust gas 17 is discharged through heat exchanger walls, not described in detail, to a cooling medium. In the illustrated working embodiment the removed thermal energy may be conveyed by the gaseous or liquid cooling medium 18 for use at some other point.

If no utilization of the thermal energy is intended or such use is not possible, it is possible to reduce the temperature of the hot exhaust gas 17 directly by the mixing therewith of cooling air. This may be performed in various different ways. Figure 2 through 5 show several possible examples in this respect.

Figure 2 shows one possible embodiment of the invention, in which the cooling device 20 provides a plurality of openings 21 in the exhaust gas duct 12. The openings 21 are for instance provided with baffle plates 22 so that owing to the flow of the exhaust gas there will be pressure differential on both sides of the wall of the exhaust gas duct through which the surrounding air 23 is drawn into the interior 24 of the exhaust gas duct. The hot exhaust gas 17 is mixed with the inflowing air 23 and then emerges as diluted and cooled exhaust gas 15 from the exhaust gas system.

In order to produce the necessary pressure differential for the introduction of cooling air into the exhaust gas duct it is also possible to utilize blowers or compressors.

Figure 3 shows one embodiment of the invention illustrating this possibility in the case of which the cooling device 30 consists of openings 31 in the exhaust gas duct 12 and of a housing 32 surrounding this part of the exhaust gas part 12, a cooling air supply tube 33 being provided with a blower 34 and opening into the housing 32. By means of the blower 34 a slight gage pressure is - 5 produced in the annular space 35 between the housing 32 and the wall of the exhaust gas duct, such pressure being sufficient to cause the cooling air 36 to flow via the opening 31 into the space 24 inside the exhaust gas duct. This cooling device 30 will be seen from figure 3 to be arranged adjacent to the outlet end of the exhaust gas duct 12. The introduction of the cooling air 36 may be aided by the arrangement of sheet metal baffles and/or a diffusor-like widening of the opening of the exhaust gas duct.

There are furthermore many possibilities for the modification of the design in accordance with figures 1, 2 and 3 in order to provide for adaptation to the particular application.

In the illustrated working embodiment of figure 4, which is similar to that of figure 2, the cooling device 20 is for instance arranged at the outlet end of the exhaust gas duct 12 and is provided with a protective housing 40, whose end surface 41 on the exhaust gas outlet side is shut off. The cooling air 23 from the environment enters in the annular space 43 defined by the blower 40 on the opposite end side 42 and thence passes through the openings 21 into the interior 24 of the exhaust gas duct.

The housing 40 and 41 serves to ensure that the exhaust gas which is hot and in certain cases may be extremely hot, is not passed into the cooling zone 20. This design offers the advantage that on the one hand the adjacent components are not unnecessarily heated up and on the other hand it is possible to provide for a better cooling of the exhaust gas 17.

If in another case it is preferred for the exhaust gas duct to be free of openings in this part, a remedy is provided by a housing 40, whose end 42 remote from the exhaust gas inlet end is open so that the exhaust gas system is shut off as far as the opening for safety reasons.

Figure 5a shows a housing 50 of this type which furthermore only encompasses a part of the outer surface of the exhaust gas duct 51. The openings 52 for the cooling air 23 are provided only in this part of the outer surface. As illustrated in cross section in figure 5b, in the case of this embodiment of the invention it is a question of an exhaust gas duct with a rectangular or square - 6 cross section, which becomes larger like a diffusor towards the outlet. The openings 52 are elongated and they each have a sheet metal guide baffle 53.

The arrangement of the cooling device 16, 20 and 30 is to 5 be selected in accordance with the amount of space available and the application. If possible an arrangement adjacent to cleaning device will be selected in order to protect the entire remaining part of the exhaust gas system against high temperature gases and more particularly overheating. If the exhaust gas duct is arranged on a wall or, as in the case of a vehicle, on the floor, then it is possible to have, for instance, a cooling device in accordance with figure 5a or figure 5b, which only need occupy a part of the circumferential extent of the exhaust gas duct. It is in this manner that the cooling device is provide on the free part of the exhaust gas duct adjacent to cleaning device.

Claims

1.An exhaust gas removal system, comprising an exhaust gas duct, a device, which is placed in the exhaust gas duct, for cleaning the exhaust gas, and a device for cooling the exhaust gas, said cooling device being thermally associated with the exhaust gas duct to cause such cooling downstream from the cleaning device.

2. The system as claimed in claim 1, wherein the cooling device is a heat exchanger.

3. The system as claimed in claim 1, wherein said cooling device is in the form of a gas mixing device with which the hot exhaust gas may be mixed with cooling air.

4. The system as claimed in claim 3, wherein the mixing device is in the form of opening in the exhaust gas duct, through which the surrounding air may be drawn into the exhaust gas duct as cooling air.

5. The system as claimed in claim 2 or in claim 4, which has the part of the exhaust gas duct with the openings is surrounded by a protective housing which is open at one end.

6. The system as claimed in any one of the preceding claims, comprising a blower or compressor, with which the cooling air may be blown into the exhaust gas duct.

7. The exhaust gas system as claimed in claim 1, substantially as described in the specification with reference to and as illustrated in figure 1 of the accompanying drawing.

8. The exhaust gas system as claimed in claim 1, substantially as described in the specification with reference to and as illustrated in figure 2 of the accompanying drawing.

9. The exhaust gas system as claimed in claim 1, substantially as described in the specification with reference to and as illustrated in figure 3 of the accompanying drawing.

10. The exhaust gas system as claimed in claim 1, substantiaiiy as described in the specification with reference to and as illustrated in figure 4 of the accompanying drawing.

11. The exhaust gas system as claimed in claim 1, substantially as described in the specification with reference to and as illustrated in figures 5a and 5b of the accompanying drawing.