WO2013090484A1

WO2013090484A1 - Fluid injection lance with balanced flow distribution

Info

Publication number: WO2013090484A1
Application number: PCT/US2012/069347
Authority: WO
Inventors: Yung T. Bui; Arvind JUJARE; Jay Venkataraghavan
Original assignee: Caterpillar Inc.
Priority date: 2011-12-15
Filing date: 2012-12-13
Publication date: 2013-06-20
Also published as: CN103998736B; US20130152555A1; DE112012005233T5; CN103998736A

Abstract

An injector configured to introduce a reductant into an exhaust stream, the injector includes: a body including a conduit with a first diameter, a nozzle (162) fluidly coupled to the conduit and disposed at a distal end of the body, and an extension extending from the distal end of the body, the extension extending from the distal end of the body by at least a distance equal to the first diameter.

Description

FLUID INJECTION LANCE WITH BALANCED FLOW DISTRIBUTION Technical Field

The present disclosure relates to an exhaust system, and more particularly, to an aftertreatment module and fluid injector lance.

Background

Internal combustion engines, including diesel engines, gasoline engines, gaseous-fuel powered engines, and other engines known in the art generate a complex mixture of exhaust gases and particulates. Components of the exhaust gases may include, among other things, oxides of nitrogen (NOx). Exhaust emission standards have become more stringent, and the amount of NOx emitted to the atmosphere by an engine may be regulated depending on the type, size and/or class of engine.

To reduce NOx, some engine manufacturers have implemented a strategy called selective catalytic reduction (SCR). SCR is an exhaust aftertreatment process where a reductant, most commonly urea ((NH₂)₂CO) or a water, urea solution, is selectively injected into the exhaust gas stream of an engine and adsorbed onto a downstream substrate. The injected urea solution decomposes into ammonia (NH₃), which reacts with NOx in the exhaust gas to form water (H₂0) and diatomic nitrogen (N₂).

In order to maximize an efficiency of conversion of the NOx, the reductant should be dispersed evenly in the flow of exhaust gases. This may be problematic due to constraints on the size of an aftertreatment module. That is, because of packaging concerns for the power system including the aftertreatment module, the length of exhaust conduit between the injector and the downstream substrate may be relatively short. Thus, it is beneficial to obtain an even distribution of reductant in a short distance in order to ensure an even distribution of reductant on the downstream substrate. United States Patent No. 7,784,276 discloses an exhaust gas purifier and a method of control therefor.

Summary

An injector configured to introduce a reductant into an exhaust stream, the injector includes: a body including a conduit with a first diameter, a nozzle fluidly coupled to the conduit and disposed at a distal end of the body, and an extension extending from the distal end of the body, the extension extending from the distal end of the body by at least a distance equal to the first diameter.

Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

Brief Description of the Drawings

Fig. 1 is a side elevation view of an embodiment of a disclosed power system;

Fig. 2 is an isometric cut-away view of an embodiment of an aftertreatment module of the disclosed power system;

Fig. 3 is a top plan illustration of a first embodiment of a diffuser, reductant injector lance assembly and mixing duct of the embodiment of an aftertreatment module of the disclosed power system;

Fig. 4 is a side elevation illustration of the first embodiment of the diffuser, reductant injector lance assembly and mixing duct of the disclosed aftertreatment module;

Fig. 5 is a partial cross-sectional view of the first embodiment of the mixing duct and reductant injector lance assembly of the disclosed system;

Fig. 6 is a partial cross-sectional view of a second embodiment of a mixing duct and reductant injector lance assembly of the disclosed system;

Fig. 7 is a partial cross-sectional view of a third embodiment of a mixing duct and reductant injector lance assembly of the disclosed system;

Fig. 8 is a side elevation illustration of a fourth embodiment of a mixing duct and reductant injector lance assembly of the disclosed system; and Fig. 9 a cross-sectional illustration taken along line 9-9' of Fig. 8 of the fourth embodiment of a mixing duct and reductant injector lance assembly of the disclosed system.

Detailed Description

Fig. 1 illustrates an exemplary power system 10. For the purposes of this disclosure, power system 10 is depicted and described as a gen-set including a generator 12 powered by a multi-cylinder internal combustion engine 14. Generator 12 and engine 14 may be generally coupled by a frame 16. It is contemplated, however, that power system 10 may embody another type of power system, if desired, such as one including a diesel, gasoline, or gaseous fuel-powered engine associated with a mobile machine, such as a locomotive, or a stationary machine, such as a pump.

Multiple separate sub-systems may be included within power system 10 to promote power production. For example, power system 10 may include among other things, an air induction system 18 and an exhaust system 20. Air induction system 18 may be configured to direct air or an air/fuel mixture into combustion chamber(s) of power system 10 for subsequent combustion. Exhaust system 20 may treat byproducts of the combustion process and discharge them to the atmosphere. Air induction and exhaust systems 18, 20 may be mechanically coupled to each other by way of one or more turbochargers 21.

Exhaust system 20 may include components that condition and direct exhaust from the cylinders of engine 14 to the atmosphere. For example, exhaust system 20 may include one or more exhaust passages 22 fluidly connected to the cylinders of engine 14, one or more turbines of the

turbochargers 21 driven by exhaust flowing through exhaust passages 22, and an aftertreatment module 24 connected to receive and treat exhaust from exhaust passages 22 after flowing through the one or more turbines of the turbochargers 21. As the hot exhaust gases exiting the cylinders of engine 14 move through the one or more turbines and expand against vanes (not shown) thereof, the one or more turbines may rotate and drive one or more compressors of the turbochargers 21 of the air induction system 18 to pressurize inlet air. Aftertreatment module 24 may treat, condition, and/or otherwise reduce constituents of the exhaust generated by engine 14 before the exhaust is discharged to the atmosphere.

As shown in Fig. 2, aftertreatment module 24 may include a base support 30, a generally box-like housing 32 (elements of which are illustrated as being transparent in order to clearly show internal elements of the aftertreatment module 24), one or more inlets 34, and one or more outlets 36 (also illustrated in Fig. 1). Base support 30 may be fabricated from, for example, a mild steel, and rigidly connected to frame 16 of power system 10 (referring to Fig. 1). Housing 32 may be fabricated from, for example, welded stainless steel, and connected to base support 30 in such a way that housing 32 can thermally expand to some degree relative to base supported 30 when housing 32 is exposed to elevated temperatures. Inlets 34 and outlets 36 may be located at one end of housing 32 such that flows of exhaust may exit housing 32 in a direction substantially perpendicular to the flow of exhaust entering housing 32. Inlets 34 may be operatively coupled to exhaust passages 22 (referring to Fig. 1) while outlets 36 may be operatively coupled to passages leading to the atmosphere (e.g., additional exhaust tubing leading to an exterior space (not shown). One or more access panels, for example a pair of oxidation catalyst access panels 40 and a pair of SCR catalyst access panels 42, may be located at strategic locations on housing 32 to provide service access to internal components of aftertreatment module 24.

Aftertreatment module 24 may house a plurality of exhaust treatment devices. For example, Fig. 2 illustrates aftertreatment module 24 as housing a first aftertreatment device consisting of one or more banks of diesel oxidation catalysts ("DOCs") 44, a second aftertreatment device consisting of a reductant dosing arrangement 46, and a third aftertreatment device consisting of one or more banks of SCR catalysts 48. It is contemplated that aftertreatment module 24 may include a greater or lesser number of aftertreatment devices of any type known in the art, as desired. DOCs 44 may be located downstream of inlets 34 and upstream of a diffuser 50.

Exhaust enters the aftertreatment module 24 via the inlets 34. The exhaust passes into the DOCs 44. After passing through the DOCs 44 and diffuser 50, the exhaust is exposed to the reductant dosing arrangement 46 through a mixing duct 51. After passing through the reductant dosing

arrangement 46, the exhaust flows through the SCR catalysts 48. Next, the exhaust may flow through clean up catalysts (not shown) before exiting the aftertreatment module 24 through outlets 36.

The DOCs 44 may each include a porous ceramic honeycomb structure, a metal mesh, a metal or ceramic foam, or another suitable substrate coated with or otherwise containing a catalyzing material, for example a precious metal, that catalyzes a chemical reaction to alter a composition of exhaust passing through DOCs 44. In one embodiment, DOCs 44 may include palladium, platinum, vanadium, or a mixture thereof that facilitates a conversion of NO to N0₂. In another embodiment, DOCs 44 may alternatively or additionally perform particulate trapping functions (i.e., DOCs 44 may be a catalyzed particulate trap), hydro-carbon reduction functions, carbon-monoxide reduction functions, and/or other functions known in the art.

In the depicted embodiment, three separate banks of DOCs 44 are disclosed as being arranged to receive exhaust in parallel from a pair of inlets 34. Each bank of DOCs 44 may include two or more substrates disposed in series and configured to receive exhaust from inlets 34. In one example, a space may exist between substrates of a single bank of DOCs 44, if desired, the space

simultaneously promoting exhaust distribution and sound attenuation. It is contemplated that any number of banks of DOCs 44 including any number of substrates arranged in series or parallel may be utilized within aftertreatment module 24, as desired.

The mixing duct 51 has an upstream open end 52 in fluid communication with the output of the DOCs 44 and a downstream end 53 in fluid communication with the one or more banks of SCR catalysts 48. In the depicted embodiment, diffuser 50 is configured as a cylinder with a flapper-type diffusing member disposed on one end thereof distal to the mixing duct 51 , although any diffuser geometry known in the art may be utilized. In the arrangement of Fig. 2, the diffuser 50 may be configured to distribute exhaust in a substantially uniform manner across the upstream open end 52 of the mixing duct 51. A reductant injector lance assembly 54 may be located at, within, or near upstream open end 52 and configured to inject a reductant into the exhaust flowing through mixing duct 51. A gaseous or liquid reductant, most commonly a water/urea solution, ammonia gas, liquefied anhydrous ammonia, ammonium carbonate, an ammine salt, or a hydrocarbon such as diesel fuel, may be sprayed or otherwise advanced into the exhaust passing through mixing duct 51.

Reductant injector lance assembly 54 may be located a distance upstream of SCR catalysts 48 and at an inlet portion of mixing duct 51 to allow the injected reductant sufficient time to mix with exhaust from power system 10 and to sufficiently decompose before entering SCR catalysts 48. That is, an even distribution of sufficiently decomposed reductant within the exhaust passing through SCR catalysts 48 may enhance NO_x reduction therein. The distance between reductant injector lance assembly 54 and SCR catalysts 48 may enhance NO_x reduction therein. The distance between reductant injector lance assembly 54 and SCR catalysts 48 (i.e., approximately the length of mixing duct 51) may be based on a flow rate of exhaust exiting power system 10 and/or on a cross- sectional area of mixing duct 51. In the example depicted in Figs. 2 and 3, mixing duct 51 may extend a majority of a length of housing 32, with reductant injector lance assembly 54 being located at upstream open end 52. The mixing duct 51 may be a conduit having an inner diameter 55 and an outer diameter 56 as illustrated in more detail in Figs. 5-7. The reductant injector lance assembly 54 may be configured to provide beneficial flow characteristics as will be discussed in more detail with respect to Figs. 3-9.

Each SCR catalyst 48 may be substantially identical in shape, size and composition. In particular, each SCR catalyst 48 may include a generally cylindrical substrate fabricated from or otherwise coated with a ceramic material such as titanium oxide; a base metal oxide such as vanadium and tungsten; zeolites; and/or a precious metal. With this composition, decomposed reductant entrained within the exhaust flowing through mixing duct 51 may be adsorbed onto the surface and/or adsorbed within each SCR catalyst 48, where the reductant may react with NO_x (either NO, N0₂ or both) in the exhaust gas to form water (H₂0) and diatomic nitrogen (N₂). Figs. 3-5 illustrate a first embodiment of a diffuser 50, reductant injector lance assembly 54 and mixing duct 51 of the embodiment of an aftertreatment module 24 of the disclosed power system 10. Fig. 5 illustrates a partial cross-sectional view of the first embodiment of the mixing duct 51 and reductant injector lance assembly 54 as viewed from the mixing duct 51 looking toward the reductant injector lance assembly 54. The reductant injector lance assembly 54 and the mixing duct 51, including upstream open end 52 and downstream end 53, together form the reductant dosing arrangement 46. The reductant injector lance assembly 54 includes a lance body 60, a nozzle 62 and a lance extension 64.

The lance body 60 may include an internal reductant conduit (illustrated in Fig. 9) extending throughout in order to convey reductant to the nozzle 62; that is, the lance body 60 may be hollow having an external diameter 61 and internal diameter 63 (illustrated in Fig. 9). The reductant conduit may have a predetermined diameter determined according to desired reductant flow rates based on the specific application of the power system 10 and desired performance of aftertreatment module 24. In one embodiment, the diameter of the reductant conduit may be 2.5 cm. The lance body 60 extends with a longitudinal axis in a first direction 66.

The nozzle 62 extends substantially perpendicular to the longitudinal axis of the lance body 60 at a distal end of the lance body 60. That is, the nozzle 62 extends downstream into the exhaust flow from the lance body 60. The nozzle 62 receives reductant from the lance body 60 and injects the reductant into the exhaust flowing within the mixing duct 51. In one

embodiment, the nozzle 62 may be configured as an air-assisted injection nozzle such that a combination of air, or other gas, and reductant is injected into the exhaust. In some embodiments, air-assisted injection of reductant provides advantages for increasing reductant flow rate and dispersal of reductant along mixing duct 51 ; however, alternative embodiments include configurations wherein air-assisted injection is omitted and reductant is supplied exclusively via alternative means, e.g., a reductant pump. In some embodiments, disposing the nozzle 62 perpendicularly downstream from the lance body 60 provides advantages for reductant dispersal as the nozzle 62 is moved further from a turbulent wake in the exhaust caused by the lance body 60. If the nozzle 62 were to be formed in the lance body 60 itself, this turbulent wake may cause undesirable deposit formation thereon which could lead to a reduction in reductant flow therethrough. In one embodiment, the nozzle 62 may be a single nozzle 62. In such an embodiment, the nozzle 62 may be centered within the mixing duct 51. In another embodiment, the nozzle 62 may include more than one nozzle 62.

The lance extension 64 extends from the lance body 60. In one embodiment, the lance extension 64 extends substantially parallel to the first direction 66. Alternative embodiments include configurations wherein the lance extension 64 extends in a different direction, e.g., in a direction angled with respect to the lance body 60 such as extending at an angle into the exhaust flow or at an angle toward the mixing duct 51. As illustrated in Figs. 3-5, the lance body 60 extends to the nozzle 62 while the lance extension 64 extends beyond the nozzle 62. The lance extension 64 may extend from the lance body 60 by a distance at least equal to the predetermined diameter of the internal reductant conduit of the lance body 60. When the lance extension 64 extends to, or beyond, this distance, improved mixing of reductant with exhaust may be achieved as discussed in more detail below. In one embodiment (not shown), the lance body 60 and lance extension 64 may together extend a distance equal to substantially the entire inner diameter 55 of the mixing duct 51.

In one embodiment, the lance extension 64 may be fluidly coupled to the internal reductant conduit of the lance body 60; that is, the lance extension 64 may also include an internal reductant conduit (not shown) capped at a furthermost extension of the lance body 60 in the first direction 66. In an alternative embodiment, the lance extension 64 may be fluidly isolated from the lance body 60 such that the lance extension 64 does not include an internal reductant conduit and the lance extension 64 may be hollow or solid.

Referring to Figs. 3-5, the reductant injector lance assembly 54 may be coupled to the aftertreatment module 24 through a through-hole 70 in housing 32. The through-hole 70 may be configured to be substantially a same shape as a cross-section of the reductant injector lance assembly 54, such that the reductant injector lance assembly 54 may be inserted into the aftertreatment module 24 therethrough. In one embodiment, the reductant injector lance assembly 54 may be coupled to a header 72. The header 72 may seal the aftertreatment module 24 such that exhaust does not exit via the through-hole 70. The header 72 may also be fluidly coupled to the internal reductant conduit of the lance body 60 of the reductant injector lance assembly 54. A connection port 74 may be disposed on the header 72 for supplying reductant to the internal reductant conduit of the lance body 60.

Fig. 6 illustrates a partial cross-sectional view of the mixing duct

51 and a second embodiment of a reductant injector lance assembly 154 as viewed from the mixing duct 51 looking toward the reductant injector lance assembly 154. The reductant injector lance assembly 154 includes a lance body 160, a nozzle 162 and a lance extension 164, similar to the previous embodiment, and also includes a cross-member 167 coupled to the lance body 160 and extending in a second direction 68 substantially perpendicular to the first direction 66. The cross-member 167 may provide improved mixing of reductant with exhaust as discussed in more detail below.

Fig. 7 illustrates a partial cross-sectional view of the mixing duct 51 and a third embodiment of a reductant injector lance assembly 254 as viewed from the mixing duct 51 looking toward the reductant injector lance assembly 254. The reductant injector lance assembly 254 includes a lance body 260, a nozzle 262 and a lance extension 264, similar to the previous embodiments, and also includes a ring mixer 267 coupled to the lance body 260. In one

embodiment, the ring mixer 267 is disposed with a center of the ring mixer 267 axially aligned with a center of the nozzle 262. The ring mixer 267 may provide improved mixing of reductant with exhaust as discussed in more detail below.

Fig. 8 is a side elevation illustration of a mixing duct and a fourth embodiment of a reductant injector lance assembly 354 of the disclosed system as viewed from the mixing duct 51 looking toward the reductant injector lance assembly 354. Fig. 9 is a cross-sectional illustration taken along line 9-9' of Fig. 8. The reductant injector lance assembly 354 includes a lance body 360, a nozzle 362 and a lance extension 364, similar to the previous embodiments, and also includes a baffle 367 coupled to the lance body 360. In one embodiment, the baffle 367 is coupled to at least one of the lance body 360 and lance extension 364. Embodiments include configurations wherein the baffle 367 may be formed separately from the lance body 360 and lance extension 364 and configurations wherein the baffle 367 may be formed as a single, unitary and indivisible component of either the lance body 360, lance extension 364 or both. The baffle 367 is provided to control flow of the exhaust passing thereby, e.g., in one embodiment the baffle 367 may reduce tribulation in the exhaust passing thereby. In one embodiment, the baffle 367 and lance body 360 and/or lance extension 364 together form a teardrop-shaped cross section. The baffle 367 provides improved mixing of reductant with exhaust as discussed in more detail below.

While the above description has described four embodiments of a reductant injector lance assembly 54, 154, 254 and 354, additional embodiments combining aspects of the previous embodiments are also within the scope of this disclosure. For example, another embodiment of the present disclosure may include baffling 367 disposed on the ring mixer 267 or the cross-member 167. Similarly, the cross-member 167 may be combined with the ring mixer 267, etc. The benefits of these configurations are discussed in more detail below.

Industrial Applicability

The aftertreatment module 24 of the present disclosure may be applicable to any power system 10 configuration where exhaust gas conditioning is desired. The aftertreatment module 24 includes at least one of the reductant injector lance assemblies 54, 154, 254 and/or 354. The various embodiments provide improved mixing of reductant with exhaust as described in more detail below.

When the power system 10 is in operation, exhaust passes through the aftertreatment module 24 for treatment as described above the aftertreatment module 24 includes the reductant dosing arrangement 46 and SCR catalysts 48. The exhaust passes through the reductant dosing arrangement 46 and carries injected reductant onto the SCR catalysts 48. In order to maximize efficiency of the SCR catalysts 48 and to minimize the total amount of reductant needed to achieve satisfactory saturation of all SCR catalysts 48, a substantially uniform distribution of reductant across each SCR catalyst 48 is desired. However, disposing components, such as a reductant injector, in the exhaust stream may lead to imbalances in the stream that are not effectively dispersed within the length of the mixing duct 51. Such a phenomenon may lead to uneven distribution of reductant on the SCR catalysts 48.

In one configuration wherein a reductant injector lance assembly (not shown) omits a lance extension, exhaust flow over the most distal portion of the lance body may cause unwanted vortex shedding that deflects injected reductant towards a side of the mixing duct 51 from which the reductant injector lance assemblies 54, 154, 254 and/or 354 extends. In such a configuration a variability from catalyst to catalyst of up to 20% may be observed. However, in embodiments wherein a lance extension 64, 164, 264 or 364 is included, the unwanted vortex shedding may be reduced, eliminated, or moved significantly away from the nozzle 62, 162, 262 or 362 such that deflection of reductant from nozzle 62, 162, 262 or 362 is reduced or eliminated.

Referring specifically to Figs. 3-5 and the first embodiment of the reductant injector lance assembly 54, the lance extension 64 is disposed at the distal end of the lance body 60 and, in one embodiment, extends from the lance body 60 by a distance at least equal to a diameter of the internal reductant conduit of the lance body 60. If the lance extension 64 extends significantly less than this amount, a reduction in deflection of reductant from the nozzle 62 may not result in a significantly more uniform distribution of reductant onto catalyst 48.

However, as the length of the lance extension 64 increases, a corresponding increase in reduction of deflection of reductant from the nozzle 62 resulting in a more uniform distribution of reductant onto catalyst 48 may be observed.

Similarly, referring to Figs. 6-9, reductant injector lance assemblies 154, 254 and 354 also include lance extensions 164, 264 and 364. In addition, each of reductant injector lance assemblies 154, 254 and 354 includes an additional feature for improving mixing of reductant with exhaust. Referring to Fig. 6, the cross-member 167 presents a wake in the exhaust flow similar to the wake of the lance extension 164 in that similar exhaust flow characteristics are presented at the nozzle 162 from at least four sides corresponding to the lance body 160, the lance extension 164 and the two portions of the cross-member 167 disposed on opposite sides of the nozzle 162. Referring to Fig. 7, the ring mixer 267 similarly presents a wake in the exhaust flow which allows a more uniform exhaust flow over the nozzle 262 from multiple sides, such as a circumference surrounding the nozzle 262. That is, the ring mixer 267 may be disposed with a center thereof axially aligned with a center of the nozzle 262. Referring to Figs. 8 and 9, the baffle 367 presents a surface which allows for laminar flow of exhaust gas therealong in a third direction 69. This baffling may alleviate non- uniformity of reductant deposition due to fluctuations in the velocity of exhaust gas in the second direction. The baffling 367 exerts a smoothing effect on exhaust gas flowing thereover.

The present disclosure also presents embodiments of injector lance assemblies 54, 154, 254 and 354 configured to introduce a reductant into an exhaust stream, the injector lance assemblies 154, 254 and 354 including; lance bodies 60, 160, 260 and 360; nozzles 62, 162, 262 and 362 fluidly coupled to, and disposed at a distal end of, the lance bodies 60, 160, 260 and 360; and lance extensions 64, 164, 264 and 364 extending from the distal end of the lance bodies 60, 160, 260 and 360, the lance extensions 64, 164, 264 and 364 configured to equalize a velocity of exhaust flow over the nozzles 62, 162, 262 and 362 in at least two directions. That is, the lance extensions 64, 164, 264 and 364 are configured such that exhaust flow over the nozzles 62, 162, 262 and 362 is more uniform, e.g., a flow velocity from a direction corresponding to the lance bodies 60, 160, 260 and 360 is substantially equal to a flow velocity from a direction corresponding to the lance extensions 64, 164, 264 and 364. The embodiment including the cross-member 167 may equalize a velocity of exhaust flow over the nozzle 162 in at least four directions. The embodiment including the ring mixer 267 may equalize a velocity of exhaust flow over the nozzle 262 in substantially all directions.

It will be apparent to those skilled in the art that various modifications and variations can be made to the exhaust system 20 and aftertreatment module 24 of the present disclosure without departing from the scope of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the system and module disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalent.

Claims

1. An injector configured to introduce a reductant into an exhaust stream, the injector comprising:

a body including a conduit with a first diameter;

a nozzle (162) fiuidly coupled to the conduit and disposed at a distal end of the body; and

an extension extending from the distal end of the body, the extension extending from the distal end of the body by at least a distance equal to the first diameter.

2. The injector assembly of claim 1, wherein the body extends in a first direction (66) and the extension extends in a second direction (68) substantially parallel to the first direction (66).

3. The injector assembly of claim 2, further comprising a cross-member (167) coupled to the body and extending in a third direction (69) substantially perpendicular to the first direction (66).

4. The injector assembly of claim 2, further comprising a ring mixer (267) coupled to the body.

5. The injector assembly of claim 4, wherein the ring mixer (267) is disposed with a center of the ring mixer (267) axially aligned with a center of the nozzle (162).

6. The injector assembly of claim 1 , wherein at least one of the body and the extension includes a teardrop-shaped cross-section.

7. The injector assembly of claim 1, wherein the extension is fiuidly isolated from the body.

8. An aftertreatment module (24) for treating constituents of exhaust gases of an internal combustion engine (14), the aftertreatment module (24) comprising:

a housing (32);

an injector disposed within the housing (32), the injector including: a body coupled to the housing (32) and including a conduit with a first diameter;

a nozzle (162) fluidly coupled to the conduit of the body and disposed at a distal end of the body; and

an extension extending from the distal end of the body, the extension extending from the distal end of the body by at least a distance equal to the first diameter; and

a mixing duct (51) disposed downstream of the injector and within the housing (32).

9. The aftertreatment module (24) of claim 8, wherein the body extends in a first direction (66) and the extension extends in a second direction (68) substantially parallel to the first direction (66).

10. The aftertreatment module (24) of claim 9, wherein the body and extension together extend a distance equal to substantially an entire diameter of the mixing duct (51).

11. The aftertreatment module (24) of claim 9, further comprising a cross- member (167) coupled to the body and extending in a third direction (69) substantially perpendicular to the first direction (66).

12. The aftertreatment module (24) of claim 8, wherein the body and extension together extend less than a distance equal to substantially an entire diameter of the mixing duct (51).

13. The aftertreatment module (24) of claim 10, further comprising a header (72) fluidly coupled to the internal reductant conduit of the body of the injector.

14. The aftertreatment module (24) of claim 8, wherein the injector is disposed within the mixing duct (51).

15. An injector configured to introduce a reductant into an exhaust stream, the injector comprising:

a body;

a nozzle (162) fluidly coupled to, and disposed at a distal end of, the body; and

an extension extending from the distal end of the body, the extension configured to equalize a velocity of exhaust flow over the nozzles (162) in at least two directions.