GB2569339A

GB2569339A - Exhaust treatment system for an engine

Info

Publication number: GB2569339A
Application number: GB1720814.1A
Authority: GB
Inventors: Ahmed Niaz Naseer
Original assignee: Perkins Engines Co Ltd
Current assignee: Perkins Engines Co Ltd
Priority date: 2017-12-14
Filing date: 2017-12-14
Publication date: 2019-06-19
Anticipated expiration: 2037-12-14
Also published as: GB201720814D0; GB2569339B; CN109958512A; CN109958512B

Abstract

Disclosed is an exhaust treatment system for an engine, the system comprising an exhaust conduit 106, a baffle 108 disposed in the conduit, wherein the baffle comprises a plurality of openings (160, figure 3) and is orientated in the downstream direction at an acute angle A relative to the longitudinal axis 118 of the conduit, and an injector 110 mounted in an injector bay 126 located downstream of the baffle, wherein the injector is orientated at an obtuse angle B in the downstream direction relative to the axis. The system preferably also comprises a static mixer 112 disposed downstream of the injector, wherein the mixer comprises a plurality of vanes 120, and a reductant catalyst (114, figure 1) disposed downstream of the mixer. The baffle may extend outwardly from the injector bay and past the central longitudinal axis. A gap 142 may be defined between an end portion 184 of the baffle and the injector bay, such that the baffle directs a portion of exhaust gas into the injector bay through the gap. The system may be a selective catalytic reduction system configured to reduce nitrous oxide (NOx) into nitrogen and water.

Description

EXHAUST TREATMENT SYSTEM FOR AN ENGINE

Technical Field [0001] The present disclosure relates to an exhaust treatment system for an engine. More particularly, the present disclosure relates to an exhaust treatment system for the engine having a reductant catalyst.

Background [0002] Exhaust treatment systems are generally used to treat and remove various pollutants from exhaust gas released from an engine, before discharging the exhaust gas into the atmosphere. One such exhaust treatment system employs a reductant, such as urea, and an exhaust treatment catalyst, such as a selective catalyst reduction (SCR) catalyst, for facilitating the removal of pollutants (such as NOx) from the exhaust gas. In such cases, the reductant is generally injected into the exhaust gas flow upstream of the catalyst. The reductant reacts with the exhaust gas while passing through the exhaust treatment catalyst and converts various pollutants into non-pollutant constituents. For example, the urea reacts with NOx present in the exhaust gas in the presence of the SCR catalyst, and converts NOx into nitrogen and water. To effectively remove the pollutants from the exhaust gas, the reductant needs to be properly and homogenously mixed with the exhaust gas.

[0003] United States Patent No. 8,621,846 relates to an exhaust gas treatment system for an internal combustion engine. The exhaust gas treatment system includes an exhaust fluid injector to deliver an exhaust fluid to the exhaust gas in the upstream direction. Further, the exhaust gas treatment system includes an exhaust flow baffle located upstream of the exhaust fluid injector. The exhaust flow baffle defines a turbulent, low pressure velocity field downstream thereof and proximate to the exhaust fluid injector.

Summary of Invention [0004] According to an aspect, an exhaust treatment system for an engine is disclosed. The exhaust treatment system includes an exhaust conduit, a baffle, and an injector. The exhaust

-2conduit receives exhaust gas from the engine. The baffle is disposed into the exhaust conduit. The baffle is oriented at a first angle relative to a central longitudinal axis of the exhaust conduit to direct a portion of exhaust gas along the baffle in a downstream direction towards an injector bay. The baffle includes a plurality of openings to facilitate a uniform flow of exhaust gas downstream of the baffle. The injector is mounted to the injector bay, and is oriented in the downstream direction at a second angle relative to the central longitudinal axis of the exhaust conduit to deliver a reductant into exhaust gas. The first angle is an acute angle and the second angle is an obtuse angle.

[0005] According to another aspect, an exhaust treatment system for an engine is disclosed. The exhaust treatment system includes an exhaust conduit to receive exhaust gas from the engine, a baffle, an injector, a static mixer, and a reductant catalyst. The baffle is disposed into the exhaust conduit, and is oriented at a first angle relative to a central longitudinal axis of the exhaust conduit to direct a portion of exhaust gas along the baffle in a downstream direction towards an injector bay. The baffle includes a plurality of openings to facilitate a uniform flow of exhaust gas downstream of the baffle. Further, the injector is mounted to the injector bay, and is oriented in the downstream direction at a second angle relative to the central longitudinal axis of the exhaust conduit to deliver a reductant into exhaust gas. The static mixer is disposed within the exhaust conduit downstream to the injector. The static mixer includes a plurality of vanes to facilitate a mixing of the reductant with exhaust gas. Also, the reductant catalyst is disposed within the exhaust conduit downstream to the static mixer to facilitate reduction of oxides of nitrogen in the exhaust gas. The first angle is an acute angle and the second angle is an obtuse angle.

Brief Description of Drawings [0006] FIG. 1 illustrates an exemplary exhaust treatment system for an engine, in accordance with an embodiment of the disclosure;

[0007] FIG. 2 illustrates an enlarged sectional view of the exhaust treatment system, in accordance with an embodiment of the disclosure;

-3[0008] FIG. 3 illustrates an enlarged perspective sectional view of the exhaust treatment system depicting an upstream facing surface of a baffle of the exhaust treatment system, in accordance with an embodiment of the disclosure;

[0009] FIG. 4 illustrates an enlarged perspective sectional view of the exhaust treatment system depicting a downstream facing surface of the baffle of the exhaust treatment system, in accordance with an embodiment of the disclosure; and [0010] FIG. 5 illustrates a perspective view of the baffle of the exhaust treatment system, in accordance with an embodiment of the disclosure.

Detailed Description [0011] FIG. 1 illustrates an exemplary exhaust treatment system 100 for an engine 102. The engine 102 may be an internal combustion engine, such as a diesel engine. Although diesel engine is contemplated, it may be appreciated that the exhaust treatment system 100 may be utilized with other types of engines, such as, but not limited to, gasoline engines, duel fuel engines, homogeneous charge compression ignition engines, and any other similar engines. For ease of description and discussion, the disclosure will be discussed in the context of the diesel engine. The exhaust treatment system 100 is configured to treat exhaust gas received from the engine 102 before releasing exhaust gas into the atmosphere. In an embodiment, the exhaust treatment system 100 is a selective catalytic reduction system 104, and is configured to reduce nitrous oxide (NOx) present in exhaust gas into nitrogen and water.

[0012] Referring to FIGS. 1, 2, 3, and 4, the exhaust treatment system 100 includes an exhaust conduit 106, a baffle 108, an injector 110, a mixer 112, and a reductant catalyst 114. The exhaust conduit 106 is coupled to the engine 102, and is configured to receive exhaust gas discharged from the engine 102. The exhaust conduit 106 facilitates a flow of exhaust gas discharged by the engine 102 to an ambient. The baffle 108 is disposed inside the exhaust conduit 106, and is oriented at a first angle ‘A’ (shown in FIG. 2) relative to a central longitudinal axis 118 of the exhaust conduit 106. The baffle 108 is configured to facilitate a uniform flow of exhaust gas downstream of the baffle 108. The details of the baffle 108 are discussed later in the description. Following in the direction of a flow of exhaust gas, the mixer 112 may be disposed inside the exhaust conduit 106 downstream to the baffle 108 and

-4the injector 110. The mixer 112 may be employed for facilitating a uniform mixing of a reductant injected by the injector 110 into the exhaust gas. In an embodiment, the mixer 112 be a static mixer 116 (as shown in FIGS 1, 2, 3, and 4). The static mixer 116 may include a plurality of vanes 120 and a plurality of openings 122 defined between the plurality of vanes 120 to facilitate a proper atomization of the reductant and uniform mixing of the reductant into exhaust gas. In an embodiment, the mixer 112 may generate a swirl flow of exhaust gas to facilitate uniform mixing of the reductant into exhaust gas. Further, the reductant catalyst 114 is disposed inside the exhaust conduit 106 and positioned downstream to the mixer 112. The reductant catalyst 114 is configured to facilitate a reduction of pollutants present in exhaust gas by the reductant. In an embodiment, the reductant may be a diesel exhaust fluid, such as ammonia, urea, etc. In such cases, the reductant catalyst 114 facilitates a reduction of oxides of nitrogen, such as nitrous oxides (NOx) present in exhaust gas into nitrogen and water.

[0013] The injector 110 is mounted to an injector bay 126 that may be formed in the exhaust conduit 106 or attached thereto, such as by welding, or the like. The injector bay 126 may include an injector mounting flange 130 (best shown in FIGS. 2, 3, and 4) to mount the injector 110. A tip portion 134 of the injector 110 protrudes through the injector mounting flange 130 and may extend towards the exhaust conduit 106. In certain implementations, an outer most end of the tip portion 134 may not extend beyond an inner surface of the injector mounting flange 130. The configuration of the injector bay 126 and an orientation of the injector mounting flange 130 cooperate to orient the injector 110 in a downstream facing manner such that an axis 136 of the injector 110 is at a second angle ‘B’, FIG. 2, with respect to the central longitudinal axis 118 of the exhaust conduit 106. Thus, the injector is 110 oriented in a downstream direction at the second angle ‘B’ relative to the central longitudinal axis 118 of the exhaust conduit 106. In an embodiment, the axis 136 of the injector 110 is at a third angle ‘C’, with respect to a normal 138 to the central longitudinal axis 118 of the exhaust conduit 106. In an embodiment, the second angle ‘B’ is an obtuse angle, while the third angle ‘C’ is an acute angle. The injector 110 is oriented in such a manner that the injector 110 delivers the reductant in the downstream direction towards the mixer 112 or the reductant catalyst 114.

-5The third angle C may be in a range from about 40° to about 70°, depending on exhaust characteristics such as flow volume and speed of exhaust gas.

[0014] Further, the injector bay 126 may define a chamber 140 for receiving a portion of exhaust gas flowing through the exhaust conduit 106. Also, the tip portion 134 (the injector 110) may extend into the chamber 140. In an embodiment, the tip portion 134 may not extend beyond the inner surface of the injector mounting flange 130. The chamber 140 may receive the portion of exhaust gas through a gap 142 defined between the baffle 108 and the injector bay 126. As shown in FIGS 1, 2, 3, and 4, the gap 142 may be defined between the injector mounting flange 130 and the baffle 108. The portion of exhaust gas follows the profile of the injector bay 126 before exiting the injector bay 126. The portion of exhaust gas is directed to the chamber 140 (injector bay 126) through the gap 142 by the baffle 108 due to the orientation (first angle ‘A’) of the baffle 108 within the exhaust conduit 106.

[0015] The baffle 108 is oriented inside the exhaust conduit 106 in such a manner that the baffle 108 directs the portion of exhaust gas along the baffle 108 in a downstream direction towards the injector bay 126. The baffle 108 may extend outwardly from the injector bay 126 into the exhaust conduit 106, and may extend past the central longitudinal axis 118 in an upstream direction away from the mixer 112.

[0016] Referring to FIGS. 1 to 5, the baffle 108 may be a plate shaped structure and may include an outer periphery 150, a plurality of lugs 152 extending outwardly from the outer periphery 150, an upstream facing surface 154, a downstream facing surface 158 (shown in FIG. 4), and a plurality of openings 160. In an embodiment, the baffle 108 may be in the form of an elliptical plate. Although, the baffle 108 is contemplated as an elliptical plate, the baffle 108 may be in the form of any other similar shaped plate such as a circular shaped plate. The plurality of openings 160 facilitates a uniform flow of exhaust gas downstream of the baffle 108. The plurality of openings 160 extends from the upstream facing surface 154 to the downstream facing surface 158 through a width of the baffle 108. Therefore, the baffle 108 allows at least a portion of exhaust gas to flow from upstream of the baffle 108 to the downstream of the baffle 108 through the plurality of openings 160. In some implementation, widths of the openings 160 disposed closer to the outer periphery 150 is larger than the widths of the openings 160 disposed distal to the outer periphery 150 and closer to a center of the

-6baffle 108. The different widths of the openings 160 may help achieve a uniform distribution of exhaust gas downstream of the baffle 108 and along a width of exhaust conduit 106.

[0017] The baffle 108 may be supported or mounted within the exhaust conduit 106 by coupling the plurality of lugs 152 with a wall 162 of the exhaust conduit 106. The plurality of lugs 152 may be coupled to the exhaust conduit 106 by welding, fastening or any other suitable method known in art. The baffle 108 is supported within the exhaust conduit 106 such that the first angle ‘A’ is defined between the downstream facing surface 158 or upstream facing surface 154 and the central longitudinal axis 118. Further, the baffle 108 is also oriented at a fourth angle ‘D’ relative to a perpendicular axis 164 to the exhaust conduit orientation. The first angle A is an acute angle and may be in a range from about 30° to about 80°, depending on exhaust characteristics such as flow volume and speed of exhaust gas. In an embodiment, the first angle ‘A’ is based on the second angle ‘B’ i.e., orientation of the baffle 108 relative to the central longitudinal axis 118 is dependent or a function of orientation of injector 110 relative to the central longitudinal axis 118. The first angle ‘A’ may be a function of the second angle ‘B’ so as to facilitate an entry of the portion of exhaust gas into the injector bay 126 through the gap 142. It may be appreciated that the second angle ‘B’ is selected such that the reductant sprayed by the injector 110 impinges or interact with the mixer

112. Further, as shown in FIG. 4, the baffle 108 may be coupled to the exhaust conduit 106 to define one or more annular passages 166 between the outer periphery 150 and the wall 162 of the exhaust conduit 106. In an embodiment, the plurality of openings 160 together with the one or more annular passages 166 may facilitate a uniform distribution of exhaust gas along the width of the exhaust conduit 106.

[0018] The baffle 108 may further include an end portion 168 (hereinafter referred as a first end portion 168) disposed proximal to the injector bay 126, and a second end portion 170 disposed away from the injector bay 126. The first end portion 168 and the injector bay 126 together defines the gap 142 therebetween through which the portion of exhaust gas is directed into the chamber 140 and hence into the injector bay 126. Further, the first end portion 168 may include a cutout 174 to provide a passage for the reductant discharged by the injector 110. The cutout 174 may be defined along the outer periphery 150 of the baffle 108, and may form an opening 176 to allow the reductant discharged by the injector 110 to enter into a

-7portion of the exhaust conduit 106 downstream of the baffle 108. In an embodiment, the cutout 174 may form a U-shaped opening along the outer periphery 150 at the first end portion 168.

[0019] The baffle 108 may further include one or more guide plates 180 extending outwardly from the upstream facing surface 154, in the upstream direction. Each guide plate 180 includes a free end 182 disposed away from the upstream facing surface 154, and a connected end 184 connected to the first end portion 168. Further, the free end 182 is disposed proximal to the central longitudinal axis 118 of the exhaust conduit 106 and the connected end 184 is disposed distal to the central longitudinal axis 118. Further, the free end 182 may be disposed distally to the cutout 174, while the connected end 184 may be disposed proximally to the cutout 174. In this manner, each guide plate 180 may extend away from the upstream facing surface 154 and may be oriented at a fifth angle Έ’ relative to the upstream facing surface 154 of the baffle 108. Therefore, each guide plate 180 may define an angle (sixth angle ‘F’) relative to the central longitudinal axis 118 of the exhaust conduit 106. In an embodiment, the sixth angle ‘F’ may be equal to the first angle ‘A’. The baffle 108 is disposed within the exhaust conduit 106 such that the free end 182 of each guide plate 180 is disposed upstream of the upstream facing surface 154. Such an arrangement of each guide plate 180 within the exhaust conduit 106 and an orientation of each guide plate 180 relative to the upstream facing surface 154 may help guide the portion of exhaust gas into the chamber 140 and hence into injector bay 126 through the gap 142. Although the one or more guide plates 180 are contemplated, it may be appreciated that the guide plates 180 may be omitted, and in such a case the inclination of baffle 108 relative to the central longitudinal axis 118 facilitates guiding the portion of exhaust gas inside the chamber 140 through the gap 142. The portion of exhaust gas entering the injector bay 126 through the gap 142 may follow a profile of the injector bay 126 before exiting the injector bay 126 downstream of the baffle 108.

Industrial Applicability [0020] During operation, exhaust gas discharged from the engine 102 passes into the exhaust conduit 106 through an inlet of the exhaust conduit 106. As exhaust gas travels through the exhaust conduit 106, the exhaust gas comes into contact with the baffle 108. Some

-8portion of exhaust gas passes through the plurality of openings 160 and through the annular passages 166, while the remaining portion is deflected and directed along the upstream facing surface 154 of the baffle 108. A flow of the portion of exhaust gas passing through the plurality of openings 160 turns uniform as soon as the portion exits the openings 160 (i.e. downstream of the baffle 108). Such uniform flow means that the portion of exhaust gas assumes an evenly distributed flow along the width of the exhaust conduit 106 instead of concentrating along any arbitrary line of fluid flow (such as along the central longitudinal axis 118). The remaining portion of exhaust gas that is deflected and directed along the upstream facing surface 154 of the baffle 108 enters the injector bay 126 through the gap 142. Further, the guide plates 180 may also help in directing the remaining portion of the exhaust gas towards the injector bay 126 through the gap 142. This portion of exhaust gas, received into chamber 140, flows along a profile of the injector bay 126.

[0021] While flowing along the profile of the injector bay 126, exhaust gas comes into contact with the reductant injected by the injector 110, and may entrain the reductant, helping initiate a reductant atomization process. Thereafter, the portion of the exhaust gas, at least partly laden with the reductant, exits the chamber 140 and return to the portion of exhaust gas that is passed downstream through the openings 160 of the baffle 108. The portion of exhaust gas flowing through the chamber 140 and hence through the injector bay 126 prevents accumulation and deposition of the reductant within the injector bay 126. Also, as the tip portion 134 of the injector 110 protrudes into the chamber 140 and hence into the injector bay 126, the portion of exhaust gas flowing into the chamber 140 may heat the tip portion 134. The heating of the tip portion 134 of the injector 110 and flow of exhaust gas around the tip portion 134 may avoid or reduce unacceptable amount of deposition and coagulation of the reductant within orifices and/or flow channels of the injector 110, thereby ensuring a normal operation of the injector 110.

Claims

What is claimed is:

1. An exhaust treatment system for an engine, the exhaust treatment system comprising:

an exhaust conduit to receive exhaust gas from the engine;

a baffle disposed into the exhaust conduit, wherein the baffle is oriented at a first angle relative to a central longitudinal axis of the exhaust conduit to direct a portion of exhaust gas along the baffle in a downstream direction towards an injector bay, the baffle includes a plurality of openings to facilitate a uniform flow of exhaust gas downstream of the baffle; and an injector mounted to the injector bay, the injector is oriented in the downstream direction at a second angle relative to the central longitudinal axis of the exhaust conduit to deliver a reductant into exhaust gas, wherein the first angle is an acute angle and the second angle is an obtuse angle.

2. The exhaust treatment system of claim 1 further including a static mixer disposed within the exhaust conduit downstream to the injector and the baffle, the static mixer including a plurality of vanes to facilitate a mixing of the reductant with exhaust gas.

3. The exhaust treatment system of claim 2 further including a reductant catalyst disposed within the exhaust conduit downstream to the static mixer.

4. The exhaust treatment system of claim 1, wherein the injector bay defines a chamber for receiving exhaust gas, the injector bay includes an injector mounting flange to mount the injector, wherein the injector extends into the chamber.

5. The exhaust treatment system of claim 2, wherein the baffle extends outwardly from the injector bay into the exhaust conduit and extends past the central longitudinal axis in an upstream direction away from the static mixer.

6. The exhaust treatment system of claim 1, wherein the baffle includes an end portion disposed proximal to the injector bay, the end portion and the injector bay defining a gap therebetween, wherein the baffle directs the portion of exhaust gas along the baffle in the downstream direction into the injector bay through the gap.

7. The exhaust treatment system of claim 6, wherein the end portion includes a cutout defined along an outer periphery of the baffle, the cutout provides a passage for the reductant discharged by the injector into the exhaust conduit.

8. The exhaust treatment system of claim 6, wherein the baffle includes an upstream facing surface, the baffle further including one or more guide plates extending outwardly from the upstream facing surface in an upstream direction to direct the portion of exhaust gas towards the gap.

9. The exhaust treatment system of claim 8, wherein the one or more guide plates are oriented in the upstream direction from the upstream facing surface at an angle relative to the central longitudinal axis of the exhaust conduit.

10. The exhaust treatment system of claim 1, wherein the baffle includes a plurality of lugs adapted to be coupled to the exhaust conduit to mount the baffle within the exhaust conduit.

11. The exhaust treatment system of claim 1, wherein the first angle is based on the second angle of the injector relative to the central longitudinal axis.

12. An exhaust treatment system for an engine, the exhaust treatment system comprising:

-Ilan exhaust conduit to receive exhaust gas from the engine;

a baffle disposed into the exhaust conduit, the baffle is oriented at a first angle relative to a central longitudinal axis of the exhaust conduit to direct a portion of exhaust gas along the baffle in a downstream direction towards an injector bay, the baffle includes a plurality of openings to facilitate a uniform flow of exhaust gas downstream of the baffle;

an injector mounted to the injector bay, the injector is oriented in the downstream direction at a second angle relative to the central longitudinal axis of the exhaust conduit to deliver a reductant into exhaust gas;

a static mixer disposed within the exhaust conduit downstream to the injector, the static mixer including a plurality of vanes to facilitate a mixing of the reductant with exhaust gas; and a reductant catalyst disposed within the exhaust conduit downstream to the static mixer to facilitate reduction of oxides of nitrogen in exhaust gas, wherein the first angle is an acute angle and the second angle is an obtuse angle.

13. The exhaust treatment system of claim 12, wherein the injector bay defines a chamber for receiving exhaust gas, the injector bay includes an injector mounting flange to mount the injector, wherein the injector extends into the chamber.

14. The exhaust treatment system of claim 12, wherein the baffle extends outwardly from the injector bay into the exhaust conduit and extends past the central longitudinal axis in an upstream direction away from the static mixer.

15. The exhaust treatment system of claim 12, wherein the baffle includes an end portion disposed proximal to the injector bay, the end portion and the injector bay defining a gap therebetween, wherein the baffle directs the portion of exhaust gas along the baffle in the downstream direction into the injector bay through the gap.

16. The exhaust treatment system of claim 15, wherein the end portion includes a cutout defined along an outer periphery of the baffle, the cutout provides a passage for the reductant discharged by the injector into the exhaust conduit.

17. The exhaust treatment system of claim 15, wherein the baffle includes an upstream facing surface, the baffle further including one or more guide plates extending outwardly from the upstream facing surface in an upstream direction to direct the portion of exhaust gas towards the gap.

18. The exhaust treatment system of claim 17, wherein the one or more guide plates are oriented in the upstream direction from the upstream facing surface at an angle relative to the central longitudinal axis of the exhaust conduit.

19. The exhaust treatment system of claim 12, wherein the baffle includes a plurality of lugs adapted to be coupled to the exhaust conduit to mount the baffle within the exhaust conduit.

20. The exhaust treatment system of claim 12, wherein the first angle is based on the second angle of the injector relative to the central longitudinal axis.