METHOD IN A FLOW DEVICE FOR EXHAUST GAS AFTERTREATMENT AND THE FLOW DEVICE

Abstract

A method, flow device and system for method of guiding a flow of exhaust gas for aftertreatment, including receiving exhaust gas into a mixing chamber; supporting a mixing tube mostly in the mixing chamber obliquely to and extending through a peripheral wall of the mixing chamber; supporting by a reactant doser mount a reactant doser that doses reactant to the mixing tube; receiving, by a peripheral exhaust gas entry in the mixing tube, exhaust gas at reactant stream arriving from the doser; and forming by a swirl arrangement, a rotating flow around a mixing tube output and enhancing exhaust gas flow through the mixing tube by forming some pressure around the mixing tube downstream from the peripheral exhaust gas entry.

Claims

1. A flow device for exhaust gas aftertreatment, comprising a mixing chamber; a mixing tube that resides mostly in the mixing chamber and is obliquely supported to and extending through a peripheral wall of the mixing chamber; and a reactant doser mount for a reactant closer to dose reactant to the mixing tube; wherein the mixing tube has a peripheral exhaust gas entry configured to receive exhaust gas at reactant stream arriving from the closer, and a mixing tube output; and the flow device has a swirl arrangement around the mixing tube, configured to form a rotating flow around the mixing tube output and to enhance exhaust gas flow through the mixing tube by forming some pressure around the mixing tube downstream from the peripheral exhaust gas entry.

2. The flow device of claim 1, wherein the mixing tube comprises a first end that extends through the peripheral wall of the mixing chamber; and the first end is closed.

3. The flow device of claim 2, wherein the mixing tube comprises a vestibule defined by the closed first end and a flange spaced apart of the first end; and the peripheral exhaust gas entry resides at least partially at the vestibule.

4. The flow device of claim 3, wherein the mixing tube comprises a second cylindrical or conical guide at the flange.

5. The flow device of claim 4, wherein the second cylindrical or conical guide is peripherally closed.

6. The flow device of claim 2, wherein the mixing tube comprises a first cylindrical or conical guide at the first end.

7. The flow device of claim 6, wherein the first cylindrical or conical guide comprises peripheral apertures for receiving exhaust gas from the vestibule.

8. The flow device of claim 1, wherein the exhaust gas entry comprises one or more apertures in the mixing tube.

9. The flow device of claim 1, wherein the mixing tube comprises one or more peripheral apertures downstream from the peripheral exhaust gas entry of the mixing tube.

10. The flow device of claim 1, wherein the mixing tube has an angle or turn dividing the mixing tube into an entry section and an exit section, wherein the exit section is within 5 degrees from parallel with a longitudinal axis of the mixing chamber.

11. The flow device of claim 1, wherein the swirl arrangement comprises two or more guides extending along at least 180 degrees around the inner wall of the mixing chamber.

12. The flow device of claim 1, wherein the two or more guides extend by at least 50% in a longitudinal direction of the mixing chamber downstream to a leading edge of the peripheral exhaust gas entry.

13. The flow device of claim 1, further configured to cause the exhaust gas to flow through the mixing tube free of rotation, while the exhaust gas flowing around the mixing tube is rotated at least at the mixing tube output.

14. A system comprising the flow device of claim 1; and a pre-rotation arrangement configured to induce a swirl in the exhaust gas arriving in the mixing chamber; the pre-rotation arrangement comprising a turbocharger or one or more dedicated swirl elements.

15. (canceled)

16. The system of claim 14, wherein the pre-rotation arrangement comprises the turbocharger; the system is configured to transfer the exhaust gas to the flow device so that the exhaust gas arrives to the mixing chamber with a residual swirl from the turbocharger; and the swirl arrangement is further configured to enforce the residual swirl.

17. A system comprising two reactant mixing devices; wherein at least one of the reactant mixing devices comprises the flow device of claim 1.

18. The system of claim 17, wherein the pre-rotation arrangement comprises the turbocharger; the system is configured to transfer the exhaust gas to the flow device so that the exhaust gas arrives to the mixing chamber with a residual swirl from the turbocharger; and the swirl arrangement is further configured to enforce the residual swirl.

19. A method of guiding a flow of exhaust gas for aftertreatment, comprising receiving exhaust gas into a mixing chamber; supporting a mixing tube mostly in the mixing chamber obliquely to and extending through a peripheral wall of the mixing chamber; supporting by a reactant doser mount a reactant doser that doses reactant to the mixing tube; receiving, by a peripheral exhaust gas entry in the mixing tube, exhaust gas at reactant stream arriving from the doser; and forming by a swirl arrangement, a rotating flow around a mixing tube output and enhancing exhaust gas flow through the mixing tube by forming some pressure around the mixing tube downstream from the peripheral exhaust gas entry.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0058] Some example embodiments will be described with reference to the accompanying figures, in which:

[0059] FIG. 1a shows an exhaust gas after-treatment system of an example embodiment;

[0060] FIG. 1b shows a cross-section of the system of FIG. 1a;

[0061] FIGS. 2a and 2b show detailed views of a mixer of FIG. 1a;

[0062] FIG. 2c shows a section view of the mixer of FIGS. 2a and 2b;

[0063] FIG. 3 shows a section view of the mixer of FIGS. 2a and 2b without a doser;

[0064] FIGS. 4a and 4b show a mixer of an alternative example embodiment;

[0065] FIG. 5 shows an exhaust gas after-treatment system of an example embodiment;

[0066] FIG. 6 schematically shows a portion of system of FIG. 1 with a turbocharger; and

[0067] FIG. 7 shows a flow chart of an exhaust gas after-treatment process of an example embodiment.

DETAILED DESCRIPTION

[0068] In the following description, like reference signs denote like elements or steps.

[0069] FIG. 1a shows an exhaust gas after-treatment system of an example embodiment, comprising a first mixer 110; an intermediate connector pipe 120; a first selective catalytic reduction, SCR, catalyst 130; a diesel oxidation catalyst, DOC 140; a diesel particulate filter, DPF 150; a second mixer 160; a second SCR 170; an output pipe 180; and a sampling port 182.

[0070] FIG. 1b shows a cross-section of the system of FIG. 1a. In this embodiment, the second mixer 160 has one or more blades partly surrounding a mixing pipe of the latter reactant mixing device and forming a rotating and circulating flow about the mixing pipe. In an example embodiment, the second mixer 160 is configured to guide exhaust gas into the mixing pipe through peripheral apertures and/or an end gap of the mixing pipe. In an example embodiment, the second mixer 160 is configured to form a rotating and advancing gas flow along the mixing pipe both inside and outside the mixing pipe.

[0071] The latter reactant mixing device may be a Proventia SuperTornado™. The latter reactant mixing device may be an apparatus for aftertreatment of exhaust gas comprising an inline housing as disclosed in U.S. Pat. No. 10,486,117 B2.

[0072] FIGS. 2a and 2b show detailed views of the mixer 110 of FIG. 1a.

[0073] FIG. 2c shows a section view of the mixer 110 of FIGS. 2a and 2b (sectioned along line A-A of FIG. 2b). FIG. 2c illustrates a mixing chamber 210 that comprises a mixing chamber input 212; swirl flow guides 214; and a mixing chamber output 216. The mixer 110 further comprises a mixing tube 220 and a doser 230. The mixing tube 220 comprises an entry section 222; an exit section 224; and a mixing tube output 226. The swirl flow guides 214 contribute to forming, collectively with other parts such as inner walls of the mixing chamber and external walls of the mixing tube 220, a swirl arrangement. The swirl arrangement produces a swirl about at least the mixing tube output 226.

[0074] FIG. 3 shows a section view of the mixer 110 of FIGS. 2a and 2b without a doser. FIG. 3 further illustrates a reactant doser mount 310 for mounting the doser 230. The mixing tube 220 has a first end 320 that closes the mixing tube 220 around the doser mount 310. Inside the mixing tube 220, there is a cylindrical or conical guide 330 connected to the first end 320. A flange 340 positioned in the entry section defines a vestibule 350. A second cylindrical or conical guide 242 is attached to the flange, for directing exhaust gas from the vestibule 350 forward along the first section 222 of the mixing tube 220. In FIG. 3, the first cylindrical or conical guide is laterally aligned with the second cylindrical or conical guide 342. The first cylindrical or conical guide 330 is drawn spaced apart of the second cylindrical or conical guide 342 such that a gap is formed therebetween. While in another example embodiment the first cylindrical or conical guide is closed, the one in FIG. 3 has peripheral apertures for receiving exhaust gas from the vestibule. Likewise, or alternatively, the second cylindrical or conical guide 342 may be peripherally closed as in FIG. 3. Alternatively, there may be some apertures in the second cylindrical or conical guide 342.

[0075] Further down the first section and/or in the second section, there may be further apertures. FIG. 3 shows a plurality of peripheral apertures 340 downstream after the vestibule 350 and a further aperture 360. An entry opening with integral guide may also be formed as shown with reference sign 370. The integral guide may guide exhaust gas into the mixing tube and/or contribute into forming a swirl about the mixing tube output 226.

[0076] FIGS. 4a and 4b show a mixer of an alternative example embodiment. In this embodiment, the doser 230 is mounted at a different angle. This is implemented by a different reactant doser mount 310′ that is not obliquely connected to the first end of the mixing tube. Additionally, here the doser mount 310′ is directly connected to the first end without a mounting pipe part.

[0077] FIG. 5 shows an exhaust gas after-treatment system 100′ of an alternative example embodiment. This embodiment differs from that of FIG. 1 in that there is a pre-swirl arrangement 510 configured to form a swirly upstream from the mixer 110. The system of FIG. 1 is convenient, for example, when mounted downstream a turbocharger such that residual swirl resides in the exhaust gas entering the mixing chamber of the mixer 110.

[0078] FIG. 6 schematically shows a portion of system of FIG. 1 with a turbocharger 610. Here, the system has a turbocharger connector, such as the mixing chamber input 212, for receiving exhaust gas from the turbocharger 610 and for transferring the received exhaust gas to the mixer 110 so that the exhaust gas arrives to the mixing chamber with a residual swirl from the turbocharger.

[0079] FIG. 7 shows a flow chart of an exhaust gas after-treatment process of an example embodiment. FIG. 7 illustrates a method of guiding a flow of exhaust gas for aftertreatment comprising various possible steps including some optional steps while also further steps can be included and/or some of the steps can be performed more than once: [0080] 700. receiving exhaust gas into a mixing chamber; [0081] 701. supporting a mixing tube mostly in the mixing chamber obliquely to and extending through a peripheral wall of the mixing chamber; [0082] 702. supporting by a reactant doser mount a reactant doser that doses reactant to the mixing tube; [0083] 703. receiving, by a peripheral exhaust gas entry in the mixing tube, exhaust gas at reactant stream arriving from the doser; [0084] 704. forming by a swirl arrangement, a rotating flow around an output of the mixing tube and enhancing exhaust gas flow through the mixing tube by forming some pressure around the mixing tube downstream from the peripheral exhaust gas entry; [0085] 705. allowing the exhaust gas to freely flow along a portion of an outer surface of the mixing tube that resides inside the mixing chamber; [0086] 706. defining in the mixing tube a vestibule by a closed first end of the mixing tube and a flange in the mixing tube, which flange is spaced apart of the first end; [0087] 707. guiding exhaust gas and reactant flows in the vestibule by an entry guide structure in the vestibule, around and extending from the reactant doser mount deeper into the mixing tube; [0088] 708. guiding the exhaust gas to flow through the mixing tube without a rotation, while guiding the exhaust gas flowing around the mixing tube to rotate at least at an exit of the mixing tube; [0089] 709. receiving by a turbocharger connector the exhaust gas from a turbocharger to the mixing chamber with some residual swirl from the turbocharger; [0090] 710. inducing a swirl in the exhaust gas arriving in the mixing chamber by a pre-rotation arrangement; [0091] 711. conducting the exhaust gas to the flow device or from the flow device to subsequent catalytic or filtration treatment by an intermediate connector pipe; [0092] 712. insulating the intermediate connector pipe to reduce heat loss; [0093] 713. insulating the mixing chamber; and/or [0094] 714. performing after-treatment by at least two reactant mixing devices.

[0095] Various embodiments have been presented. It should be appreciated that in this document, words comprise; include; and contain are each used as open-ended expressions with no intended exclusivity.

[0096] The foregoing description has provided by way of non-limiting examples of particular implementations and embodiments a full and informative description of the best mode presently contemplated by the inventors for carrying out the present disclosure. It is however clear to a person skilled in the art that the present disclosure is not restricted to details of the embodiments presented in the foregoing, but that it can be implemented in other embodiments using equivalent means or in different combinations of embodiments without deviating from the characteristics of the present disclosure.

[0097] Furthermore, some of the features of the afore-disclosed example embodiments may be used to advantage without the corresponding use of other features. As such, the foregoing description shall be considered as merely illustrative of the principles of the present disclosure, and not in limitation thereof. Hence, the scope of the present disclosure is only restricted by the appended patent claims.