EP4095365A1 - Exhaust gas heating device for combustion engines, in particular for marine engines - Google Patents

Abstract

The invention relates to an exhaust gas heating device (10), in particular for the exhaust aftertreatment of the exhaust gas from ship engines, with an inner pipe (16) which has an exhaust gas inlet (14) and an overflow opening (24), between which a heating duct (26) is formed , a burner (20) which is assigned to the heating channel (26), an outer tube (12) which surrounds the inner tube (16), so that a flow channel (30) from the overflow opening (24) of the inner tube (16) to a Outlet (18) is formed. The invention also relates to an exhaust gas aftertreatment system with a diesel particle filter and a corresponding exhaust gas heating device (10).

Description

The invention relates to an exhaust gas heating device, in particular for the exhaust aftertreatment of the exhaust gas from ship engines, with an inner tube that has an exhaust gas inlet and an overflow opening, between which a heating channel is formed, a burner that is assigned to the heating channel, and an outer tube that surrounds the inner tube.

Such an exhaust gas heating device can be used to heat the exhaust gas of an internal combustion engine in order to bring a downstream exhaust gas aftertreatment device to operating temperature in a comparatively short time when the engine is cold started. If the exhaust gas aftertreatment device is a particle filter, the exhaust gas heating device can be used to initiate regeneration of the particle filter when the temperature of the exhaust gas flowing through the particle filter is increased to the ignition temperature of the deposited particles.

Exhaust gas heating devices are known in which the exhaust gas is heated with a burner. A burner tube protrudes into a straight exhaust pipe. The exhaust gas and the hot burner gases are swirled with the help of a continuous mixer. In order to prevent the burner tube from overheating, the cold exhaust gas, before being heated, is directed to the burner tube to cool the burner tube. The disadvantage of such exhaust gas heating devices is that they require a relatively large amount of installation space for the mixing process and have little installation flexibility, since different components are required for different installation positions.

It is the object of the invention to provide an exhaust gas heating device which has a compact construction and high assembly flexibility.

The object is achieved by an exhaust gas heating device, with an inner tube that has an exhaust gas inlet and an overflow opening, between which a heating channel is formed, a burner that is assigned to the heating channel, an outer tube that surrounds the inner tube, so that a flow channel is formed from the overflow opening of the inner pipe to an outlet, the exhaust gas inlet, the overflow opening and the outlet being arranged in such a way that the flow direction from the exhaust gas inlet to the overflow opening runs at least in sections opposite to the flow direction from the overflow opening to the outlet. A number of advantages are achieved by this nested arrangement: The structure is technically simple, but the deflection between the inner and outer tubes alone leads to good turbulence and thus good mixing of the fuel gas and exhaust gas. The exhaust gas outlet can be arranged in different positions with little effort, without affecting the principle of operation and without having to modify many components. Using the inner tube ensures that the outer tube has no contact with the burner flame. Therefore, the outer tube does not have to be formed of a high-temperature-resistant material, and the insulation requirements can be reduced. Finally, it is ensured that the inner tube does not overheat, since exhaust gas flows around it on the outside and is thereby cooled.

In one embodiment of the invention, the burner is designed in such a way that the flame it generates is shorter than the distance from the burner to the overflow opening. This ensures that at most the inner tube can come into contact with the burner flame; the outer tube behind it cannot come into direct contact with the burner flame.

It can be provided that the inner tube has a pre-combustion chamber which, viewed from the overflow opening, is at a greater distance from the overflow opening than the exhaust gas inlet, the burner being arranged on the pre-combustion chamber. In this way, the flame root of the burner flame is outside of a turbulent flow area at the exhaust gas inlet. In addition, the flame root is protected by the pre-combustion chamber. This results in a stable, undisturbed and easily controllable burner flame.

In one embodiment of the invention, a swirl body is provided for swirling and redirecting the exhaust gas in the flow channel. Due to the turbulence, the exhaust gas is better mixed with the hot burner gases, which results in an even temperature profile at the outlet. In addition, the swirl body improves the flow of the exhaust gas.

The swirl body is preferably provided immediately after the overflow opening, with the swirl body being fastened to an end region of the outer tube that faces away from the burner. In this way, the swirler helps to redirect the flow and also protects the end of the outer tube from direct contact with hot burner gases.

A further aspect of the invention provides that additional mixing elements are provided in the flow channel. This further improves the mixing of the gases.

The mixing elements are preferably attached to the inner tube on the one hand and to the outer tube on the other hand. In addition to the improved turbulence of the burner gases and the exhaust gas, the mixing elements serve as spacers between the inner and outer tubes, which increases mechanical stability.

In one embodiment of the invention, the swirl body and the mixing elements are designed in such a way that they introduce a swirl in the same direction into the flow. A particularly advantageous mixture of the gases is achieved in this way.

The flow is preferably deflected by essentially 90° after the exhaust gas inlet and by essentially 180° after the overflow opening. As a result, a particularly simple and compact structure can be achieved with a flow path that is particularly long compared to the external dimensions.

In one embodiment variant of the invention, the inner tube consists at least in sections of high-temperature-resistant stainless steel. In this way, this component is protected from overheating despite direct contact with the burner flame.

A further aspect of the invention provides that the outer tube consists of conventional steel, stainless steel or boiler plate. An inexpensive material can be used here.

In a further embodiment of the invention, a flame guide element can be provided within the inner tube. With the help of the flame control element, the burner flame can be additionally guided and protected.

Preferably, the flame baffle extends from the pre-combustion chamber into the area of the exhaust gas inlet to protect the burner flame from the turbulent inlet flow. This creates a very stable flame that is easy to control.

In another embodiment of the invention, the flame guide element is a perforated flame guide tube. In this way, the burner flame is particularly well protected from turbulence in the flow and is also guided on all sides by the flame guide tube, which results in a particularly stable flame.

The object is also achieved according to the invention by an exhaust gas aftertreatment system with a diesel particulate filter and an exhaust gas heating device which is flow-connected to the diesel particulate filter, the exhaust gas heating device having an inner pipe which has an exhaust gas inlet and an overflow opening, between which a heating duct is formed, a burner and a Has outer tube, which surrounds the inner tube, so that a flow channel is formed from the overflow opening of the inner tube to an outlet, wherein the direction of flow in the heating channel is at least partially opposite to the direction of flow in the flow channel. Of course, the advantages that were discussed for the exhaust gas heating device also apply to the exhaust gas aftertreatment system.

• Fig. 1 eine perspektivische Ansicht der Abgaserwärmungsvorrichtung;
• Fig. 2 einen Längsschnitt durch die Abgaserwärmungsvorrichtung aus Fig. 1;
• Fig. 3 einen Längsschnitt durch die Abgaserwärmungsvorrichtung aus Fig. 1 mit Brennerflamme und angedeuteter Abgasströmung;
• Fig. 4 einen Längsschnitt durch eine zweite Ausführungsform der Abgaserwärmungsvorrichtung mit Flammleitelement und
• Fig. 5 einen Längsschnitt durch eine dritte Ausführungsform der Abgaserwärmungsvorrichtung mit Flammleitrohr.

Further features and advantages of the invention emerge from the following description and from the accompanying drawings, to which reference is made. In the drawings show:

• 1 a perspective view of the exhaust gas heating device;
• 2 a longitudinal section through the exhaust gas heating device 1 ;
• 3 a longitudinal section through the exhaust gas heating device 1 with burner flame and exhaust gas flow indicated;
• 4 a longitudinal section through a second embodiment of the exhaust gas heating device with flame guide element and
• figure 5 a longitudinal section through a third embodiment of the exhaust gas heating device with flame guide tube.

the figures 1 and 2 show a first embodiment of an exhaust gas heating device 10 with an outer tube 12, which serves as a housing. An exhaust gas inlet 14 , which is assigned to an inner pipe 16 , protrudes from the outer pipe 12 through an opening.

The outer pipe 12 has an outlet 18 on the side opposite the exhaust gas inlet 14 .

However, it is conceivable that the outlet 18 can be offset in a range of 180°, i.e. 90° forwards or 90° backwards, on the outer tube 12, as indicated by arrows in figure 1 is clarified.

Furthermore, a pre-combustion chamber 22 which is attached to the inner pipe 16 protrudes from the outer pipe 12 . A burner 20 is fastened to the pre-combustion chamber 22, the burner 20 being designed here as a swirl burner.

The inner tube 16 and the outer tube 12 are arranged essentially concentrically to one another and extend along a central axis A. The exhaust gas inlet 14 is formed by a lateral connector which runs orthogonally to the central axis A here. In this exemplary embodiment, the outlet 18 is also designed as a lateral socket which runs orthogonally to the center axis A.

The outer tube 12 surrounds the inner tube 16. This forms a flow channel 30 between the inner tube 16 and the outer tube 12, which is fluidly connected to the outlet 18 (see FIG 2 ).

The inner tube 16 has a round cross section here. A substantially T-shaped structure is formed together with the exhaust gas inlet 14 and a pre-combustion chamber 22 explained later.

In the exemplary embodiment shown, the central axes of the pre-combustion chamber 22 and of the inner tube 16 are arranged concentrically. The central axis of the exhaust gas inlet 14 extends at an angle of 90° to the central axis of the precombustion chamber 22 or the inner pipe 16.

It is also possible that the central axis may deviate by a range of ± 15° from the orientation shown.

At the end facing away from the burner 20 , the inner pipe 16 has an overflow opening 24 so that a heating channel 26 is formed between the exhaust gas inlet 14 and the overflow opening 24 , the heating channel 26 being flow-connected to the flow channel 30 .

This results in a defined flow path, which initially runs via the exhaust gas inlet 14 into the inner tube 16 and there away from the burner 20 to the overflow opening 24 . The flow path is deflected there and runs parallel back in the flow channel 30 and then ends in the outlet 18.

Additional elements can also be attached or preferably incorporated into the overflow opening 24 . It is thus conceivable that the inner pipe 16 in the area of the overflow opening 24 has, for example, bevels which are directed outwards or inwards.

The pre-combustion chamber 22 is fastened to the left-hand part of the inner tube 16 , and the burner 20 is in turn attached to the pre-combustion chamber 22 . The pre-combustion chamber 22 protrudes from an opening in the outer tube 12 . Thus, the burner 20 is easily accessible from the outside and can be easily replaced.

The pre-combustion chamber 22 is thus located at a greater distance from the transfer opening 24 than the exhaust gas inlet 14 when viewed from the transfer opening 24 , since the pre-combustion chamber 22 is attached to the left-hand part of the inner pipe 16 .

In the embodiment shown, the precombustion chamber 22 has a round cross section, with an opening for the burner 20 being present on a side facing away from the overflow opening 24 .

A swirl body 28 is fastened to the outer tube 12 on the side facing away from the burner 20 . The swirl body is arranged immediately after the overflow opening 24 . In the embodiment shown, the swirl body 28 is attached concentrically to the overflow opening 24 . However, it is also conceivable for the swirl body 28 to be fastened in a radially offset manner.

The swirl body 28 here has a conical base body with a plurality of curved vanes that extend from the center of the swirl body 28 to the projected diameter of the overflow opening 24 .

Additional mixing elements 32 are arranged in the flow channel 30 . These are fastened on the one hand to the outer tube 12 and on the other hand to the inner tube 16 and thus form, among other things, a spacer between the outer tube 12 and the inner tube 16. The mixing elements 32 can be designed as straight or curved metal sheets.

The following is based on the figure 3 the function of the exhaust gas heating device 10 is described.

The exhaust gas, e.g. the exhaust gas of a diesel engine, flows in through the exhaust gas inlet 14 and is then deflected by 90° when it enters the heating channel 26 . In the heating channel 26, the exhaust gas hits the burner flame 34, which is generated by the burner 20. The exhaust gas is heated and mixed by the burner flame 34 and the hot burner gases, resulting in a gas mixture.

The gas mixture then continues to flow in the heating channel 26 in the direction of the overflow opening 24, where the heating channel 26 ends. After the overflow opening 24, the gas mixture hits the swirler 28, which redirects the gas mixture into the flow channel 30 by 180° and causes it to swirl in order to improve the mixing of the gases. Reversing the direction of flow by 180° also helps with the mixing of the gases.

In addition to this, the burner 20 is designed as a swirl burner in order to introduce a swirl into the flow from the burner 20 .

Provision can also be made for elements not shown here to be incorporated into the overflow opening 24, which serve to improve the mixing. This can be, for example, slopes on the overflow opening 24 that are directed inwards or outwards in order to introduce an additional swirl into the flow.

Further mixing elements 32 are provided in the flow channel 30 in order to further improve the mixing of the gases, so that there is a uniform temperature profile in the gas mixture at the outlet 18 .

The mixing elements 32 and the swirl body are preferably designed in such a way that they introduce a unidirectional swirl into the flow, since it has been found that a particularly advantageous mixture of the gases can be achieved in this way.

In the flow channel 30, the already heated gas mixture flows over the hot outer wall of the inner tube 16. As a result, the gas mixture is further heated and the inner tube 16 is correspondingly cooled.

Up to the outlet 18, at which the flow is deflected again by 90°, the gas mixture is heated to a temperature that is above the reaction temperature of the particles that have accumulated in a downstream diesel particle filter (not shown). These particles can thus be burned out of the diesel particle filter, which regenerates it.

In order to protect the flame root 36 from flow turbulence in a turbulence area 38 at the exhaust gas inlet 14, the precombustion chamber 22, viewed from the overflow opening 24, is at a greater distance from the overflow opening 24 than the exhaust gas inlet 14. The flame root 36 is additionally the pre-combustion chamber 22 itself is protected. A particularly stable and easily controllable burner flame 34 is thus made possible.

The burner 20 is designed in such a way that the burner flame 34 it generates is shorter than the distance from the burner 20 to the overflow opening 24. This can be adjusted, for example, via the ratio of fuel to ambient air that is drawn in in the burner. The speed of the exhaust gas flowing through the inner pipe 16 also has an influence. Different In other words, the inner tube 16 is longer than the burner flame 34, thereby avoiding direct flame contact between the swirler 28 and the end of the outer tube 12 lying behind it.

Due to the direct flame contact and the high temperatures of up to 1500° C. in the heating channel 26, the inner tube 16 consists at least in sections of high-temperature-resistant stainless steel in order to avoid damage due to overheating. The swirl body 28 can also consist of such a material in order to additionally protect the outer tube 12 lying behind it. However, the inner tube 16 can also consist entirely of high-temperature-resistant stainless steel.

The inner tube 16 and the swirl body 28 protect the outer tube 12 from direct flame contact. Therefore, the outer tube 12 can be made of a material that has lower heat resistance requirements than the material of the inner tube 16. Therefore, the outer tube 12 can be made of boiler plate or conventional stainless steel, such as V2A or V4A, for example. In addition, external hot spots that can lead to insulation problems are avoided.

The reversal of flow by essentially 180°, combined with the nested arrangement of outer tube 12 and inner tube 16, provides a particularly compact exhaust gas heating device 10 with very good mixing behavior. In addition, the exhaust gas heating device 10 has a particularly advantageous cooling principle of the inner tube 16 by flow reversal, the inner tube being cooled by the already heated gas mixture. Furthermore, the exhaust gas heating device 10 is particularly easy to assemble and flexible in design due to the flexible position of the outlet 18 .

In figure 4 a second embodiment of the exhaust gas heating device 10 is shown. The same reference numerals are used for the components known from the first embodiment, and reference is made to the above explanations.

The basic principle of the exhaust gas heating device according to the second embodiment is the same as that of the first embodiment. Therefore, only the differences are explained below.

In the second embodiment, a flame guide element 40 is provided on the inner tube 16 . The flame guide element 40 is designed here as a simple metal sheet and protrudes into the area of the exhaust gas inlet 14 into the heating duct 26 .

The flame baffle 40 protects the burner flame 34 from flow turbulence and partially shields the burner flame 34 from the inlet flow.

In figure 5 a third embodiment of the exhaust gas heating device is shown. The same reference numerals are used for the components known from the previous embodiments, and reference is made to the above explanations in this respect.

In the exhaust gas heating device 10 according to the third embodiment, the inner pipe 16 and the exhaust gas inlet 14 together form a substantially L-shaped pipe. On the side opposite the overflow opening 24 , the inner tube 16 has an opening through which the flame guide element 40 protrudes into the heating channel 26 .

The flame guide element 40 protrudes into a region of the exhaust gas inlet 14 in the heating channel 26 and is designed as a flame guide tube. The flame guide tube can also be perforated.

The flame guide element 40 also serves here as additional protection for the burner flame 34 and shields it from flow turbulence in the area of the exhaust gas inlet 14 .

The perforation of the flame guide tube achieves a good compromise between protecting the burner flame 34, heating the exhaust gas and introducing oxygen into the flame.

Claims (15)

Exhaust gas heating device, in particular for the exhaust aftertreatment of the exhaust gas from ship engines, with an inner tube (16) which has an exhaust gas inlet (14) and an overflow opening (24), between which a heating duct (26) is formed, a burner (20), which is assigned to the heating channel (26), an outer tube (12) which surrounds the inner tube (16), so that a flow channel (30) is formed from the overflow opening (24) of the inner tube (16) to an outlet (18), wherein the exhaust gas inlet (14), the overflow opening (24) and the outlet (18) are arranged such that the flow direction from the exhaust gas inlet (14) to the overflow opening is at least partially opposite to the flow direction from the overflow opening (24) to the outlet ( 18) runs. Exhaust gas heating device according to Claim 1, characterized in that the burner (20) is designed in such a way that the flame it generates is shorter than the distance from the burner (20) to the overflow opening (24). Exhaust gas heating device according to Claim 1 or Claim 2, characterized in that the outlet (18) is arranged on the outer pipe (12). Exhaust gas heating device according to one of the preceding claims, characterized in that the inner tube (16) has a precombustion chamber (22) which, viewed from the overflow opening (24), is at a greater distance from the overflow opening (24) than the exhaust gas inlet (14), the burner being located at the pre-combustion chamber (22). Exhaust gas heating device according to one of the preceding claims, characterized in that a swirl body (28) is provided for swirling and redirecting the exhaust gas in the flow channel (30). Exhaust gas heating device according to Claim 5, characterized in that the swirl body (28) is provided immediately after the overflow opening (24), the swirl body (28) being fastened to an end region of the outer pipe (12) remote from the burner (20). Exhaust gas heating device according to one of the preceding claims, characterized in that additional mixing elements (32) are provided in the flow channel (30) which are attached on the one hand to the inner tube (16) and on the other hand to the outer tube (12). Exhaust gas heating device according to one of the preceding claims, characterized in that the swirl body (28) and the mixing elements (32) are designed in such a way that they introduce a swirl in the same direction into the flow. Exhaust gas heating device according to one of the preceding claims, characterized in that the flow is deflected by essentially 90° after the exhaust gas inlet (14) and by essentially 180° after the overflow opening (24). Exhaust gas heating device according to one of the preceding claims, characterized in that the inner pipe (16) consists at least in sections of high-temperature-resistant stainless steel. Exhaust gas heating device according to one of the preceding claims, characterized in that the outer tube (12) consists of conventional steel, stainless steel or boiler plate. Exhaust gas heating device according to one of the preceding claims, characterized in that a flame guide element (40) is provided within the inner tube (16). Exhaust gas heating device according to Claim 12, characterized in that the flame guide element (40) extends from the precombustion chamber (22) into the region of the exhaust gas inlet (14) in order to protect the flame from the turbulent inlet flow. Exhaust gas heating device according to Claim 12 or 13, characterized in that the flame guide element (40) is a perforated flame guide tube. Exhaust aftertreatment system with a diesel particulate filter and an exhaust gas heating device (10), which is flow-connected to the diesel particulate filter, wherein the exhaust gas heating device (10). Inner pipe (16), which has an exhaust gas inlet (14) and an overflow opening (24), between which a heating channel (26) is formed, a burner (20) and an outer pipe (12), which the inner pipe (16) surrounds, so that a flow channel (30) is formed from the overflow opening (24) of the inner tube (16) to an outlet (18), the direction of flow in the heating channel (26) running at least in sections opposite to the direction of flow in the flow channel (30).

Images