Field of the invention
[0001] The present disclosure relates to a mixer for an exhaust gas
treatment system.
Background of the invention
[0002] Inline exhaust layouts are widely being used in exhaust after
treatment for commercial vehicles. They have a compact mixing section, which does the task of atomizing and mixing of the ammonia (main component of ad-blue) with the exhaust gas for NOx reduction at the Selective Catalytic Reduction brick. If the atomizing does not happen efficiently, the ad-blue droplets do not evaporate for the mixing to happen, thus resulting in urea deposition in the mixing section. Further if the mixing of the exhaust gas with ammonia does not happen efficiently, results in poor catalyst utilization and/or non-compliance with emission targets.
[0003] Patent Application JP2002066283A discloses an exhaust gas
mixer for mixing the exhaust gas flowing through a duct is equipped with a center shaft, which is turned in the axial direction of the mixer along the flow direction of the exhaust gas, and a plurality of revolving blades radially provided to the center shaft. The exhaust gas is formed into a spiral revolving stream having a clear vortex center to be uniformly mixed in the direction crossing the flow direction of the exhaust gas at a right angle by mixing diffusion utilizing the mixing diffusion effect and

interference of the revolving stream, and the partial mixing and whole mixing of the exhaust gas are performed at the same time.
Brief description of the accompanying drawings
[0004] An embodiment of the invention is described with
reference to the following accompanying drawings:
[0005] Fig. 1 depicts a solid view (1A) and a transparent view (1B)
of the mixer.
[0006] Fig. 2 depicts an exploded view of the mixer.
Detailed description of the drawings
[0007] Figure 1 depicts a mixer (100) for an exhaust gas treatment
system. Figure 1(A) depicts the transparent view of the mixer (100) and Figure 1(B) depicts a solid view of the mixer (100). The mixer (100) comprises at least a baffle plate (101) affixed to a mixing unit (102). The mixing unit (102) is placed in the exhaust gas pipe (103) downstream from a dosing module and upstream from a selective catalytic reduction (SCR) module. The mixing unit (102) is placed vertically in the cross-section of the EGT pipe (103), the bottom of the mixing unit (102) is not in contact with the Exhaust gas pipe (103) in the operative configuration of the EGT system.
[0008] A sleeve (106) is affixed to the operative top section of the
mixing unit (102). The sleeve (106) is in fluid communication with a tip

of the dosing module (not shown in the drawing). A plurality of louvers (104) are present on the outer peripheral walls of the mixing unit (102). Each of the louvers (104) are an opening on the outer peripheral surface of the mixing unit (102) such that the gases from the exhaust gas pipe (103) enter the mixing unit (102) tangentially.
[0009] A plurality of stationary blades (105) are attached on the
inner peripheral walls of the mixing unit (102). Each of the plurality of blades (105) are three dimensional blades. Each blade corresponds to a set of louvers (1041). The louvers located circumferentially along the outer periphery of the mixing unit (102) at a particular vertical height of the mixing unit (102) form the set of louvers (1041). Hence the mixing unit (102) has at least two or more sets of louvers, with each set corresponding to a particular vertical height.
[0010] Figure 2 depicts an exploded view of the mixer (100)
illustrating the mixing unit (102) comprising plurality of louvers (104), plurality of blades (105) along with a baffle plate (101) and sleeve (106). The baffle plate (101) is affixed to the mixer (100) to ensure that the exhaust gases are directed towards the louvers present on the outer periphery of the mixing unit (102). The conventionally used baffle plates (101) are but not limited to an S-shaped plate.
[0011] The louvers (104) are an opening on the outer periphery on
the mixing unit (102) with a raised window that protects the opening on

three sides and keeps it open on the fourth. The shape of this window can be one of the many known to person skilled in the art. The shape of the window is chosen such that the gases coming from the exhaust gas pipe (103) enter inside the mixing unit (102) tangentially.
[0012] Allowing the exhaust gas to enter inside the mixing unit
(101) tangentially, creates a ‘swirl’. This swirl ensures that proper mixing
of the ammonia (main component of ad-blue) with exhaust gas occurs.
The plurality of blades (105) extending towards the center of the mixer
(100) from its inner periphery, obstruct free fall of ad-blue. As explained
above each set of louvers (1041) have one corresponding blade. This
positioning of the blades (105) across the vertical length of the mixing unit
(102) ensures breaking down of the larger droplets of ammonia into
smaller ones for easier atomization. Atomization leads to breaking of
liquid ammonia into smaller droplets
[0013] Ad-blue (liquid ammonia) is dosed into the mixing unit (102)
with the help of the sleeve. It travels through the mixing unit (102) due to inertial pressure and hits one of the blades (105) of the mixing unit (102) protruding towards the center from the inner peripheral walls of the mixing unit (102). Simultaneously, exhaust gas is directed into the mixing unit (102) in a tangential manner through the plurality of louvers (104). The liquid ammonia droplets get progressively broken down as it traverses throughout the length of the mixer (100) because of the blades. The exhaust gas entering the mixer (100) creates a swirl because of the

tangential entry and mixes effectively with the broken down ammonia droplets. This mixture of exhaust gas and ammonia escapes through the bottom of the mixer (100) and enters the Selective catalytic reduction (SCR) module. Reduction reactions occur in the SCR module to reduce NOx to harmless nitrogen. The concept of a swirl generating using the louvers and atomization of the ammonia using the blades ensures that urea deposition in the mixing unit (102) and poor catalyst utilization in the SCR module is mitigated making the mixer (100) robust.
[0014] This idea to develop a mixer (100) for an exhaust gas
treatment system is aimed at solving critical issues prevailing in the prior-art. In accordance with the embodiments of the invention described above the mixer (100) enhances the process of atomization leading to uniform distribution of ammonia and exhaust gas. Better uniformity in turn prevents crystallization of ammonia. By avoiding crystallization in the mixer (100), creation of unnecessary back-pressure in the exhaust gas pipe (103) is also avoided. Further uniform distribution leads to better heat control in the EGT system which ultimately helps in reducing emissions.
[0015] It must be understood that the embodiments explained in the
above detailed description are only illustrative and do not limit the scope of this invention. Any modification to the mixer (100) for an exhaust gas treatment system are envisaged and form a part of this invention. The scope of this invention is limited only by the claims.

We claim:
1. A mixer (100) for an exhaust gas treatment (EGT) system
comprising at least a baffle plate (101) affixed to a mixing unit
(102), the mixing unit (102) placed in the exhaust gas pipe (103)
downstream from a dosing module and upstream from a selective
catalytic reduction (SCR) module, characterized in that mixing unit
(102):
a sleeve (106) affixed to the operative top section of the
mixing unit (102), the sleeve (106) in fluid communication
with a tip of the dosing module;
plurality of louvers (104) present on the outer peripheral
walls of the mixing unit (102);
plurality of stationary blades (105) attached on the inner
peripheral walls of the mixing unit (102), where each blades
corresponds to a set of louvers (1041).
2. The mixer (100) for an exhaust gas treatment (EGT) system as claimed in claim 1, where the mixing unit (102) is placed vertically in the cross-section of the EGT pipe (103), the bottom of the mixing unit (102) is not in contact with the Exhaust gas pipe (103) in the operative configuration of the EGT system.
3. The mixer (100) for an exhaust gas treatment (EGT) system as claimed in claim 1, where each of the louvers (104) are an opening

on the outer peripheral surface of the mixing unit (102) such that the gases from the exhaust gas pipe (103) enter the mixing unit (102) tangentially.
4. The mixer (100) for an exhaust gas treatment (EGT) system as claimed in claim 1, where each of the plurality of blades (105) are three dimensional blades.
5. The mixer (100) for an exhaust gas treatment (EGT) system as claimed in claim 1, where the louvers located circumferentially along the outer periphery of the mixing unit (102) at a particular vertical height of the mixing unit (102) form a set of louvers (1041).