Urea mixer

Abstract

The present invention relates to the field of tail gas treatment, and in particular to a urea mixer. The urea mixer comprises a second shell, a urea nozzle fixed to the upper end of the second shell, a partition plate and a spiral plate are arranged in the second shell, a support pipe is arranged in the middle of the spiral plate, and the spiral plate and the shell form a spiral airflow channel. The tail gas enters the airflow channel to be accelerated and rotated, thereby improving the mixing efficiency, urea decomposition, and mixing uniformity.

Description

Technical Field

[0001] The invention relates to the field of tail gas treatment, in particular to a urea mixer. Background Art

[0002] The function of the urea mixer is to break up and atomize the urea aqueous solution sprayed from the urea nozzle in the diesel internal combustion engine after-treatment system, so as to achieve full and uniform mixing of the urea aqueous solution with the hot exhaust gas discharged from the diesel internal combustion engine.

[0003] See also Figure 1 , a Chinese invention patent with publication number CN109653843A discloses an SCR urea mixer for a diesel internal combustion engine exhaust aftertreatment system, comprising a cylindrical shell and a urea nozzle seat arranged on the shell, characterized in that: the front end and the rear end of the shell both have flat panels sealed and connected to the shell to form a cylindrical cavity, and the cylindrical cavity is a mixing chamber, an expansion mixing chamber, and an SCR catalyst from the front end to the rear end; the mixing chamber comprises: an air intake end panel at the front end of the shell, an air outlet end panel that forms a mixing chamber with the air intake end panel, the urea nozzle seat is arranged on the shell wall that forms the mixing chamber, the air intake end panel is opened and connected to the air intake port arranged along the circumference of the mixing chamber, the air intake port is arranged at the circumferential front end of the urea nozzle seat, a guide plate with a spiral structure and a convergent flow feature is arranged in the mixing chamber along the circumference, and the air outlet end panel opens an air outlet to connect to the expansion mixing chamber; the expansion mixing chamber comprises: a cavity formed by the air outlet end panel and the front end face of the SCR catalyst, and a spoiler that can change the gas flow state is radially arranged in the axial middle of the cavity; The outer peripheral wall of the SCR catalyst is sealed and fixed to the inner wall of the shell and is arranged behind the expansion mixing chamber.

[0004] The structure in the prior art is relatively complex, and the mixing stroke in the front section is relatively long, which easily causes deposition in the mixing chamber, thereby affecting the mixing efficiency. Summary of the invention

[0005] The present invention aims to provide a urea mixer which can improve mixing efficiency, urea decomposition and mixing uniformity.

[0006] To achieve the above advantages, the urea mixer provided by the present invention includes a second shell and a urea nozzle fixed to the upper end of the second shell. A partition and a spiral plate are arranged in the second shell. A support tube is arranged in the middle of the spiral plate. The spiral plate and the shell form a spiral airflow channel.

[0007] In one embodiment of the present invention, the partition is provided with a second spoiler and a third spoiler extending toward the spiral plate, the second spoiler is located above the third spoiler, and the third spoiler is larger than the second spoiler.

[0008] In one embodiment of the present invention, the partition is provided with a first air flow inlet and a second air flow inlet, the first air flow inlet is larger than the second air flow inlet, the first air flow inlet is located above the second spoiler, and the second air flow inlet is located below the third spoiler.

[0009] In one embodiment of the present invention, the exhaust gas can enter the air flow channel through the first air flow inlet, the second spoiler and / or the third spoiler in sequence or through the second air flow inlet.

[0010] In one embodiment of the present invention, a plurality of spray ports are provided at one end of the spiral plate facing away from the partition plate, and the spray ports are connected to the air flow channel.

[0011] In one embodiment of the present invention, the second spoiler and the third spoiler are both provided with a plurality of through holes.

[0012] In one embodiment of the present invention, the second shell is provided with thermal insulation cotton, and the thermal insulation cotton is ceramic fiber cotton.

[0013] In one embodiment of the present invention, the exhaust gas enters the air flow channel to be accelerated and rotated.

[0014] In one embodiment of the present invention, the urea nozzle is perpendicular to the second spoiler and the third spoiler.

[0015] In one embodiment of the present invention, the second air flow inlet is used to blow part of the mixed exhaust gas into the air flow channel.

[0016] In the present invention, the tail gas is accelerated and rotated when entering the air flow channel, thereby improving the mixing efficiency, urea decomposition and mixing uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The figure shows the structure schematic diagram of the SCR urea mixer used in the diesel internal combustion engine exhaust after-treatment system in the prior art.

[0018] Figure 2 Shown is a schematic structural diagram of an exhaust gas treatment assembly according to a first embodiment of the present invention.

[0019] Figure 3 Shown Figure 2 Schematic diagram of the structure of the electrically heated catalyst of the exhaust gas treatment assembly.

[0020] Figure 4 Shown Figure 3 Schematic diagram of a cross-section of an electrically heated catalyst of an exhaust gas treatment assembly.

[0021] Figure 5 Shown Figure 2Schematic diagram of the structure of the urea mixer of the exhaust gas treatment assembly.

[0022] Figure 6 Shown Figure 5 Front view of the urea mixer of the exhaust gas treatment assembly.

[0023] Figure 7 Shown Figure 5 Rear view of the urea mixer of the exhaust gas treatment assembly.

[0024] Figure 8 Shown Figure 5 A cross-sectional schematic diagram of a urea mixer of an exhaust gas treatment assembly.

[0025] Fig. 9 Shown Figure 2 A top view of the particulate filter of the exhaust treatment assembly.

[0026] Fig.10 Shown Figure 2 A partial cutaway schematic diagram of the particulate filter of the exhaust treatment assembly.

[0027] Fig.11 Shown Figure 2 Schematic diagram of the structure of the tail catalyst of the exhaust gas treatment assembly. DETAILED DESCRIPTION

[0028] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of the specific implementation method, structure, characteristics and effects of the present invention in combination with the accompanying drawings and preferred embodiments.

[0029] See also Figure 2 , Figure 3 The urea mixer of the first embodiment of the present invention is a part of the exhaust gas treatment assembly, which includes an electric heating catalyst 1, a urea mixer 2, a particulate trap 3, and a tail catalyst 4 which are connected by flanges in sequence. The electric heating catalyst 1, the urea mixer 2, the particulate trap 3, and the tail catalyst 4 are all provided with heat preservation cotton 5.

[0030] See also Figure 4 The electrically heated catalyst 1 comprises a first shell 11 and a connecting pipe 12 connected to one end of the first shell 11. A first spoiler 13, a heater 14, and a metal carrier 15 are sequentially arranged inside the first shell 11, and a first mounting bracket 16 is arranged outside the first shell 11. The first shell 11 is also provided with a pair of positive and negative electrode connectors 17 electrically connected to the heater 14 respectively, and the positive and negative electrode connectors 17 are threadedly connected to the first shell 11.

[0031] The connecting pipe 12 is vertically connected to the first shell 11, and the connecting pipe 12 is provided with an air inlet 121, and the axial distance between the air inlet 121 and the end face of the heater 14 is ≤70mm. The first spoiler 13 has a plurality of through holes a, and the through holes a at the lower part of the first spoiler 13 are smaller than the through holes a at the upper part of the spoiler, so that the uniformity of the end face of the heater 14 is ≥95%. When the tail gas enters the first shell 11 from the air inlet 121, since the connecting pipe 12 is vertical to one end of the first shell 11, the tail gas is more concentrated in the lower part of the first shell 11, and since the through holes a at the lower part of the first spoiler 13 are smaller than the through holes a at the upper part of the first spoiler 13, the passage of the tail gas at the lower part is reduced, which plays a role of uniform diversion.

[0032] During use, the exhaust gas or airflow enters the housing from the air inlet 121, then passes through the through hole a of the spoiler, and then contacts the heater 14, and the heated exhaust gas reacts with the metal carrier 15. The electric heating catalyst 1 (EHC) adopts the method of current preheating, which can make the catalyst of the metal carrier 15 reach the ignition temperature of the catalyst within 5 to 10 seconds after the engine is started, thereby reducing the emission of harmful substances in the first few minutes after starting.

[0033] See also Figure 5 , Figure 6 , Figure 7 The urea mixer 2 includes a second shell 21, a urea nozzle 22 fixed to the upper end of the second shell 21, a partition 23 and a spiral plate 24 are arranged in the second shell 21, the partition 23 is located at one end close to the metal carrier 15, a support pipe 241 for supporting the spiral plate 24 is arranged in the middle of the spiral plate 24, and the spiral plate 24 and the second shell 21 form a spiral air flow channel 242. A plurality of spray ports 243 are arranged at one end of the spiral plate 24 facing away from the partition 23.

[0034] See also Figure 8 The partition plate 23 is provided with a second spoiler 231 and a third spoiler 232 extending toward the spiral plate 24, the second spoiler 231 is located above the third spoiler 232, and the third spoiler 232 is larger than the second spoiler 231. The urea nozzle 22 is perpendicular to the second spoiler 231 and the third spoiler 232.

[0035] The partition 23 is provided with a first air flow inlet 233 and a second air flow inlet 234. The first air flow inlet 233 is larger than the second air flow inlet 234. The first air flow inlet 233 is located above the second spoiler 231, and the second air flow inlet 234 is located below the third spoiler 232. The gas can enter the air flow channel 242 through the first air flow inlet 233, the second spoiler 231 and / or the third spoiler 232 or through the second air flow inlet 234 in sequence. The urea nozzle 22 is mainly dispersed and remixed through the third spoiler 232. Since the urea nozzle 22 has a certain inclination angle, the second spoiler 231 is used to evenly divert part of the exhaust gas and prevent the uniform spraying of urea from being affected and part of the urea from being broken.

[0036] During use, the urea nozzle 22 sprays urea, and most of the exhaust gas passes through the first air flow inlet 233 and is mixed with urea through the first air flow inlet 233; the mixed exhaust gas passes through the third spoiler 232 to produce urea fragmentation and decomposition and flows into the air flow channel 242; a small part of the exhaust gas passes through the second air flow inlet 234, and the mixed exhaust gas moved to the lower part is blown into the air flow channel 242 to prevent urea deposition; then, the exhaust gas that has been preliminarily mixed enters the air flow channel 242 and is accelerated and rotated; finally, the further mixed exhaust gas is discharged and fragmented from the spray port 243, and evenly diffused to the end face of the DPF carrier 32 of the particulate collector 3.

[0037] By making full use of the engine exhaust gas flow to break up and decompose the urea droplets, the urea liquid entering the mixer is fully atomized and preliminarily mixed with the engine exhaust gas, and then further mixed through the rotation and acceleration of the air flow channel 242, thereby improving the mixing efficiency, urea decomposition and mixing uniformity.

[0038] See also Fig. 9 , Fig.10 The particulate trap 3 includes a third shell 31, a DPF carrier 32 located in the third shell 31, and a pair of differential pressure pipes 33 connected to the third shell 31, and the ends of the differential pressure pipes 33 are located at both ends of the DPF carrier 32. The DPF carrier 32 is coated with an active coating, which is a precious metal catalyst, so that it has the function of an SCR carrier 44, further reducing the content of nitrogen oxides in the exhaust gas.

[0039] An air outlet pipe 34 with a gradually decreasing diameter is disposed at the end of the third shell 31 , and a second mounting bracket 35 is disposed outside the air outlet pipe 34 .

[0040] See also Fig.11 The tail catalyst 4 includes a fourth shell 41, one end of which is connected to the outlet pipe 34, and the other end of which is provided with an outlet port 42. The first mounting bracket 16 and the second mounting bracket 35 are both provided with a metal heat insulation layer.

[0041] The fourth housing 41 is provided with a fourth spoiler 43, an SCR carrier 44, an ASC carrier 45, a guide plate 46, and a muffler 47 in sequence. The outlet pipe 34 increases the distance between the DPF carrier 32 and the SCR carrier 44, thereby reducing the aging of the SCR carrier 44. The ASC carrier 45 is located at the rear end of the SCR carrier 44, and reduces the ammonia leaked from the exhaust gas after passing through the SCR carrier 44 through catalytic oxidation.

[0042] The first spoiler 13 , the second spoiler 231 , the third spoiler 232 , and the fourth spoiler 43 are all provided with a plurality of through holes a.

[0043] The guide plate 46 is provided with a plurality of air holes 461, one end of the muffler 47 is an inlet 471 fixed to the guide plate 46 and close to the ASC carrier 45, a plurality of muffler holes 472 are provided on one side of the muffler 47 close to the inlet, and the other end of the muffler 47 is an outlet 42. The exhaust gas treated by the ASC carrier 45 can be discharged from the outlet 42 through the inlet or through the air holes 461 and the muffler holes 472 in sequence, thereby reducing noise pollution.

[0044] The exhaust gas enters the electric heating catalyst 1 through the air inlet 121, is mixed with urea through the urea mixer 2, and then the particulate matter is captured by the particulate trap 3, and then is decomposed into nitrogen and water by the tail catalyst 4 to reduce the ammonia in the exhaust gas, and finally is discharged through the outlet 42. The treated exhaust gas meets the national emission standards.

[0045] In the present invention, heat preservation cotton is arranged outside the electric heating catalyst, the urea mixer, the particle collector and the tail catalyst, so as to reduce the temperature loss of the assembly.

[0046] In the present invention, the DPF carrier is coated with an active coating so that it has the function of an SCR carrier.

[0047] In the present invention, an ASC carrier is added to the tail catalyst to capture excess ammonia, thereby improving emission standards.

[0048] In the present invention, the tail catalyst is provided with a muffler pipe, thereby reducing noise pollution.

[0049] In the present invention, the through holes at the lower portion of the first spoiler are smaller than the through holes at the upper portion of the spoiler, so that the uniformity of the contact between the exhaust gas and the end surface of the heater is ≥95%, further improving the catalytic efficiency.

[0050] In the present invention, the second air flow inlet is used to blow part of the mixed exhaust gas into the air flow channel, thereby avoiding the deposition of urea.

[0051] In the present invention, the tail gas is accelerated and rotated when entering the air flow channel, thereby improving the mixing efficiency, urea decomposition and mixing uniformity.

[0052] The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A urea mixer, characterized in that: It comprises a second shell and a urea nozzle fixed to the upper end of the second shell, wherein a partition plate and a spiral plate are arranged in the second shell, a support pipe is arranged in the middle of the spiral plate, and the spiral plate and the shell form a spiral airflow channel; The partition is provided with a second spoiler and a third spoiler extending toward the spiral plate, the second spoiler is located above the third spoiler, and the third spoiler is larger than the second spoiler; The partition is provided with a first air flow inlet and a second air flow inlet, the first air flow inlet is larger than the second air flow inlet, the first air flow inlet is located above the second spoiler, and the second air flow inlet is located below the third spoiler; The exhaust gas may enter the air flow channel through the first air flow inlet, the second spoiler and / or the third spoiler in sequence or through the second air flow inlet; The second air flow inlet is used to blow part of the mixed exhaust gas into the air flow channel.

2. The urea mixer according to claim 1, characterized in that: A plurality of spraying ports are arranged at one end of the spiral plate facing away from the partition plate, and the spraying ports are communicated with the air flow channel.

3. The urea mixer according to claim 1, characterized in that: The second spoiler and the third spoiler are both provided with a plurality of through holes.

4. The urea mixer according to claim 1, characterized in that: The second shell is provided with thermal insulation cotton outside, and the thermal insulation cotton is ceramic fiber cotton.

5. The urea mixer according to claim 1, characterized in that: The exhaust gas enters the air flow channel and is accelerated and rotated.

6. The urea mixer according to claim 1, characterized in that: The urea nozzle is perpendicular to the second spoiler and the third spoiler.

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