Three-stage series mixer for stationary source SCR (selective catalytic reduction) aftertreatment system

Abstract

The utility model relates to a three-stage series mixer for a fixed source SCR (Selective Catalytic Reduction) post-processing system, which structurally comprises an air inlet pipe, a round-to-square connecting part and an SCR catalyst chamber which are connected with one another, a urea nozzle is arranged on the side surface of the front end of the air inlet pipe, and a blade type mixer is arranged on the rear side of the urea nozzle in the air inlet pipe. Large-blade rotational flow mixers are arranged on the rear side of the blade type mixer in the air inlet pipe at intervals, and a rectifying pore plate is arranged at the tail end in the round-to-square connecting part close to the SCR catalyst chamber. The utility model has the advantages that the structural design is reasonable, urea liquid drops and airflow can be fully mixed through the first-stage mixer and the second-stage mixer, so that the urea liquid drops reach a higher mixing degree before entering the round-to-square section, and the situation that the distribution of NH3 is influenced due to the gathering effect of vortex on the urea liquid drops is avoided. And the three-stage rectification pore plate can further eliminate the influence of the vortex on the airflow after the round-to-square section, so that the influence of the vortex on the ammonia gas distribution on the front end surface of the carrier is reduced, and the uniformity of the ammonia gas distribution can be improved.

Description

Technical Field

[0001] The utility model relates to a mixer for a fixed source SCR post-processing system, in particular to a three-stage series mixer for the fixed source SCR post-processing system. Background Art

[0002] To meet emission requirements, a fixed-source SCR (Selective Catalytic Reduction) after-treatment system is used to treat vehicle exhaust, which can effectively reduce NOx emissions and has obvious energy-saving characteristics.

[0003] In the existing technology, the fixed source SCR after-treatment system has a high requirement for back pressure, usually less than 1.5kPa, and the exhaust temperature of the fixed source is generally high, and the risk of crystallization is relatively small compared to automotive after-treatment. Therefore, a mixer is usually not provided, or only a first-stage mixer is provided to mix urea and airflow. However, due to the circular rotating square section structure, the urea droplets cannot be fully mixed before entering the circular rotating square section, resulting in more airflow vortices and incomplete mixing, which has an adverse effect on the uniformity of ammonia distribution at the front end of the carrier, often resulting in low carrier utilization and substandard emissions. Utility Model Content

[0004] The utility model proposes a three-stage series mixer for a fixed source SCR post-treatment system, which aims to overcome the above-mentioned shortcomings of the prior art, so that urea droplets and airflow are fully mixed before entering the circular-to-square section, thereby improving the uniformity of ammonia distribution.

[0005] The technical solution of the utility model is: a three-stage series mixer for a fixed source SCR after-treatment system, whose structure includes an intake pipe, a round-to-square connection part and an SCR catalyst chamber connected to each other, a urea nozzle is installed on the side of the front end of the intake pipe, a blade mixer is arranged behind the urea nozzle in the intake pipe, a large-blade swirl mixer is arranged at intervals behind the blade mixer in the intake pipe, and a rectifying orifice plate is arranged at the inner end of the round-to-square connection part near the SCR catalyst chamber. When the three-stage series mixer is used, urea droplets are sprayed from the urea nozzle and fall on the first-stage blade mixer in the direction of the airflow. The urea spray hits the blade mixer, and the large droplets are broken into small droplets. The small droplets stick to the blade mixer and absorb heat to decompose into NH3. They are broken by the first-stage blade mixer for the first mixing. Then, the droplets that are not absorbed and decomposed pass through the second-stage large-blade cyclone mixer with the airflow. The second-stage large-blade cyclone mixer can make the airflow rotate violently. While rotating violently with the airflow, the urea droplets are fully mixed with the airflow and the previously decomposed NH3, and further decomposed into NH3 during the rotation disturbance process. The gas and urea droplets are mixed for the second time. The airflow after the secondary mixing enters the circular-to-square connection part. In this space, the airflow forms a vortex due to the structural shape, and then passes through the three-stage rectifying orifice plate. The airflow after passing through the rectifying orifice plate is decelerated and the direction is relatively uniform, and finally enters the SCR catalyst chamber.

[0006] Preferably, a first temperature sensor and a second temperature sensor are respectively provided near both ends of the intake pipe.

[0007] Preferably, the blade mixer includes a transverse plug-in plate, a vertical plug-in plate and an annular mounting shell, several layers and the transverse plug-in plate and the vertical plug-in plate are plugged into each other, the ends of the top and bottom transverse plug-in plates are welded to the inner side of the mounting shell by welding overlaps, and the transverse plug-in plates except the top and bottom are evenly provided with blades staggered up and down.

[0008] Preferably, the large-blade swirl mixer includes a swirl blade and a swastika-shaped connecting piece, and a centrally symmetrical swirl blade is provided on each of the four sides of the connecting piece, and the outer end of the connecting piece is connected to the inner wall of the air inlet pipe.

[0009] Advantages of this utility model: The rational structural design allows for thorough mixing of urea droplets and airflow through the primary and secondary mixers, achieving a high degree of mixing before the urea droplets enter the circular rotating square section, thus preventing eddy currents from agglomerating the urea droplets and thus affecting the distribution of NH3. The tertiary rectifying orifice further eliminates the effect of eddy currents on the airflow after the circular rotating square section, thereby reducing the impact of eddy currents on ammonia distribution on the front face of the carrier and improving the uniformity of ammonia distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1It is a structural schematic diagram of a three-stage series mixer for a fixed source SCR post-treatment system of the utility model.

[0011] Figure 2 This is a schematic structural diagram from another angle of the three-stage series mixer used in the fixed source SCR post-treatment system of the utility model.

[0012] Figure 3 It is a perspective view of a three-stage series mixer for a fixed source SCR post-treatment system of the present invention.

[0013] Figure 4 The utility model is a structural diagram of a blade mixer in a three-stage series mixer for a fixed source SCR post-treatment system.

[0014] Figure 5 The utility model is a structural schematic diagram of a large-blade swirl mixer in a three-stage series mixer for a fixed source SCR post-treatment system.

[0015] Figure 6 The utility model is a structural schematic diagram of a rectifying orifice plate in a three-stage series mixer for a fixed source SCR post-processing system.

[0016] In the figure, 1 is the intake pipe, 11 is the first temperature sensor, 12 is the second temperature sensor, 2 is the round-to-square connection part, 3 is the SCR catalyst chamber, 4 is the urea nozzle, 5 is the blade mixer, 51 is the mounting shell, 52 is the horizontal plug-in plate, 521 is the blade, 53 is the vertical plug-in plate, 54 is the welding overlap, 6 is the large-blade swirl mixer, 61 is the swirl blade, 62 is the connecting piece, and 7 is the rectifying orifice plate. DETAILED DESCRIPTION

[0017] The present invention will be further described in detail below with reference to the embodiments and specific implementation methods.

[0018] like Figure 1 、 3 As shown, a three-stage series mixer for a fixed source SCR after-treatment system has a structure comprising an intake pipe 1, a round-to-square connection part 2 and an SCR catalyst chamber 3 connected to each other. A urea nozzle 4 is installed on the side of the front end of the intake pipe 1. A first temperature sensor 11 and a second temperature sensor 12 are respectively provided near both ends of the intake pipe 1. A blade mixer 5 is provided behind the urea nozzle 4 in the intake pipe 1. A large-blade swirl mixer 6 is provided at intervals behind the blade mixer 5 in the intake pipe 1. A rectifying orifice plate 7 is provided at the inner end of the round-to-square connection part 2 near the SCR catalyst chamber 3.

[0019] According to the above structure, a three-stage series mixer is adopted. Urea droplets are sprayed from the urea nozzle 4 and fall on the first-stage blade mixer 5 in the direction of the airflow. The urea spray hits the blade mixer 5, and the large droplets are broken into small droplets. The small droplets adhere to the blade mixer 5 and are adsorbed and decomposed into NH3 by endothermic absorption. After being broken by the first-stage blade mixer 5, the droplets that are not adsorbed and decomposed pass through the second-stage large-blade cyclone mixer 6 with the airflow. The second-stage large-blade cyclone mixer 6 can cause the airflow to rotate violently. While rotating violently with the airflow, the urea droplets are fully mixed with the airflow and the previously decomposed NH3. They are further decomposed into NH3 during the rotation disturbance process. The gas and urea droplets are mixed for the second time. The airflow after the secondary mixing enters the round-to-square connecting portion 2. In this space, the airflow forms a vortex due to the structural shape, and then passes through the third-stage rectifying orifice plate 7. After passing through the rectifying orifice plate 7, the airflow is decelerated and has a relatively uniform direction, and finally enters the carrier (SCR catalyst chamber 3).

[0020] like Figure 4 As shown, the blade mixer 5 includes a horizontal plug-in plate 52, a vertical plug-in plate 53 and an annular mounting shell 51. Several layers of the horizontal plug-in plates 52 and the vertical plug-in plates 53 are plugged into each other. The ends of the top and bottom horizontal plug-in plates 52 are welded to the inner side of the mounting shell 51 through welding overlaps 54. Except for the top and bottom, the horizontal plug-in plates 52 are evenly provided with blades 521 staggered up and down.

[0021] like Figure 5 As shown, the large-blade swirl mixer 6 includes a swirl blade 61 and a swastika-shaped connecting piece 62. A swirl blade 61 is provided on each of the four sides of the connecting piece 62 in a centrally symmetrical manner. The outer end of the connecting piece 62 is connected to the inner wall of the intake pipe 1.

[0022] The components described above are all prior art, and those skilled in the art can use any model and existing design that can achieve their corresponding functions.

[0023] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the creative concept of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A three-stage series mixer for a stationary source SCR post-treatment system, characterized in that: The invention comprises an intake pipe (1), a round-to-square connection part (2) and an SCR catalyst chamber (3) which are connected to each other. A urea nozzle (4) is installed on the side of the front end of the intake pipe (1). A blade mixer (5) is arranged behind the urea nozzle (4) in the intake pipe (1). A large blade swirl mixer (6) is arranged at intervals behind the blade mixer (5) in the intake pipe (1). A rectifying orifice plate (7) is arranged at the inner end of the round-to-square connection part (2) near the SCR catalyst chamber (3).

2. A three-stage series mixer for a stationary source SCR post-treatment system according to claim 1, characterized in that: A first temperature sensor (11) and a second temperature sensor (12) are respectively provided near both ends of the air intake pipe (1).

3. The three-stage series mixer for a stationary source SCR post-treatment system according to claim 1, characterized in that: The blade mixer (5) includes a transverse plug-in plate (52), a vertical plug-in plate (53) and an annular mounting shell (51), wherein a plurality of layers and the transverse plug-in plates (52) and the vertical plug-in plates (53) are plugged into each other, and the ends of the top and bottom transverse plug-in plates (52) are welded to the inner side of the mounting shell (51) through welding overlaps (54), and blades (521) are evenly arranged on the transverse plug-in plates (52) except for the top and bottom.

4. The three-stage series mixer for a stationary source SCR post-treatment system according to claim 1, characterized in that: The large-blade swirl mixer (6) comprises a swirl blade (61) and a swastika-shaped connecting piece (62). The four sides of the connecting piece (62) are respectively provided with a centrally symmetrical swirl blade (61). The outer end of the connecting piece (62) is connected to the inner wall of the air inlet pipe (1).

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