Urea mixer and tail gas aftertreatment system

Abstract

The utility model provides a urea mixer and a tail gas after-treatment system, the exhaust back pressure is small, the urea crushing effect is good, the tail gas mixing effect is good, a baffle is arranged in a mixer cylinder and divides the mixer cylinder into a front part and a rear part, and a mixing pipe mounting part is formed on the baffle through bending. A mixing pipe is installed on the mixing pipe installation part, the upper half portion of the mixing pipe is located on the front side of the baffle, the lower half portion of the mixing pipe penetrates through the baffle and extends to the rear side of the baffle, the top of the mixing pipe is connected with a urea nozzle installation base, and the upper half portion and the lower half portion of the mixing pipe are provided with an air inlet and an air outlet respectively. The at least two urea crushing parts are sequentially arranged in the radial direction of the mixer barrel, each urea crushing part comprises a plurality of steel bars which are arranged in the cross section of the mixer barrel at intervals, and the steel bars of every two adjacent urea crushing parts are arranged in the cross section of the mixer barrel in a crossed mode.

Description

TECHNICAL FIELD

[0001] The utility model relates to exhaust gas aftertreatment technical field, concretely relates to a kind of urea mixers and exhaust gas aftertreatment system. BACKGROUND

[0002] Current diesel engine exhaust gas aftertreatment all need to be equipped with mixer to improve urea decomposition efficiency and reducing agent distribution uniformity, for the diesel engine adapted to European seven regulations, such as the diesel engine of double injection structure, the existing mixer is used, and the back pressure is large;Especially for the large displacement diesel engine above 4L, it may need to use 2 groups of mixers, and the back pressure is larger;Excessive back pressure can affect the operating efficiency of diesel engine, cause exhaust not to be smooth, adversely affect the combustion of engine, increase fuel consumption, so as to affect the power, economy and the like of engine. SUMMARY

[0003] In view of the above problems, the utility model provides a kind of urea mixers and exhaust gas aftertreatment system, and its exhaust back pressure is small, and urea is not easy to crystallize, and mixing effect is good.

[0004] Its technical scheme is as follows: a kind of urea mixer, including mixer cylinder, baffle is provided in the mixer cylinder, the baffle separates the mixer cylinder into two parts, the baffle is formed by bending and is provided with mixing pipe mounting portion, mixing pipe is installed on the mixing pipe mounting portion, the upper half of the mixing pipe is located on the front side of the baffle, the lower half of the mixing pipe extends to the back side of the baffle through the baffle, the top of the mixing pipe is connected with urea nozzle mounting seat, the upper and lower halves of the mixing pipe are respectively provided with air inlet and air outlet, characterized by: the mixing pipe is provided with urea breaking piece, the urea breaking piece is provided with at least two and is sequentially arranged along the radial direction of the mixer cylinder, the urea breaking piece includes a plurality of steel bars arranged at intervals in the cross section of the mixer cylinder, and the steel bars of adjacent two urea breaking pieces are cross arranged in the cross section of the mixer cylinder.

[0005] Further, the steel bar is provided with a layer on the urea breaking piece.

[0006] Further, the steel bar is provided with multiple layers on the urea breaking piece, and the steel bars of different layers are staggered.

[0007] Further, the urea breaking piece includes a ring body with the same size as the mixing pipe, and the two ends of the steel bar are connected to the ring body.

[0008] Further, the mixing pipe is provided with a plurality of sections, wherein the urea breaking piece is arranged between the two adjacent mixing pipe sections, and the ring body of the urea breaking piece is welded to the pipe wall of the mixing pipe.

[0009] Further, the top of the mixing pipe is provided with a variable diameter step portion, an upper end of the variable diameter step portion is provided with an opening, the opening is arranged towards the urea nozzle mounting seat, and a urea nozzle is mounted on the urea nozzle mounting seat.

[0010] Further, the air inlet comprises a main air inlet and an auxiliary air inlet, windows are formed in the pipe wall of the upper half of the mixing pipe to form the main air inlet, the main air inlets are arranged at intervals around the pipe wall of the mixing pipe, and guide vanes are arranged at the main air inlets, and the auxiliary air inlet is arranged on the variable diameter step portion.

[0011] Further, the lower half of the mixing pipe is provided with the air outlet towards one side of the baffle, and the air outlet is arranged as a plurality of strip-shaped small windows arranged along the pipe wall of the mixing pipe.

[0012] Further, the steel rods of the two adjacent urea breaking pieces are arranged vertically in the cross section of the mixer cylinder.

[0013] Further, the bottom of the mixing pipe is connected with a plug cover, and the plug cover is welded on the cylinder mixer.

[0014] Further, when the mixer is used in the aftertreatment system of a diesel engine with a displacement of less than 4L, the diameter of the steel rod is 0.5mm-1mm; when the mixer is used in the aftertreatment system of a diesel engine with a displacement of 4L-10L, the diameter of the steel rod is 1mm-2mm; and when the mixer is used in the aftertreatment system of a diesel engine with a displacement of more than 10L, the diameter of the steel rod is 1mm-5mm.

[0015] An exhaust gas aftertreatment system, characterized by comprising the urea mixer.

[0016] The urea mixer of the utility model, through setting urea breaking piece in mixing pipe, adopting urea breaking piece with steel rod structure to atomize urea droplet, effectively improve atomization effect of urea, cross arrangement of steel rod and multilayer setting of urea breaking piece enhance atomization effect, reduce risk of urea crystallization, cross installation of steel rod of multiple groups of urea breaking piece form more efficient urea droplet breaking and mixing effect, also do not bring obvious back pressure, through multilayer, staggered arrangement of steel rod design of breaking piece, effectively reduce exhaust back pressure, make the application of mixer on large displacement diesel engine more feasible. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a schematic view of the urea mixer in the embodiment;

[0018] Figure 2 It is a schematic view of the urea mixer in the embodiment from the first perspective of hidden mixer cylinder;

[0019] Figure 3 is a schematic view of the urea mixer in the embodiment from a second perspective of the hidden mixer barrel;

[0020] Figure 4 is a front view of the hidden mixer barrel of the urea mixer in the embodiment;

[0021] Figure 5 is a sectional view of the A-A direction of Figure 4

[0022] Figure 6 is a perspective view of two urea breakers in another embodiment;

[0023] Figure 7 is a front view of two urea breakers in another embodiment stacked in sequence;

[0024] Figure 8 is a sectional view of the B-B direction of Figure 7 DETAILED DESCRIPTION

[0025] To make the technical problems solved by the present application, the technical solutions adopted and the technical effects achieved more clear, the technical solutions of the embodiments of the present application are described in further detail below. In the description of the present specification, the description of the terms "embodiment" and the like means that the specific features, structures or characteristics described in connection with the embodiment are contained in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example.

[0026] See Figures 1 to 8 , the urea mixer of the present application comprises a mixer barrel 1, a baffle 2 is arranged in the mixer barrel 1, the baffle 2 divides the mixer barrel 1 into two parts, a mixing pipe mounting portion 201 is formed by bending on the baffle 2, a mixing pipe 3 is mounted on the mixing pipe mounting portion 201, the upper half of the mixing pipe 3 is located on the front side of the baffle 2, the lower half of the mixing pipe 3 extends to the rear side of the baffle 2 through the baffle 2, the top of the mixing pipe 3 is connected to a urea nozzle mounting seat 6, the upper and lower halves of the mixing pipe 3 are respectively provided with an air inlet and an air outlet 302, a urea breaker 4 is arranged in the mixing pipe 3, the urea breaker 4 is provided with at least two, a plurality of urea breakers 4 are arranged in sequence along the radial direction of the mixer barrel 1, the urea breaker 4 comprises a plurality of steel rods 401 arranged at intervals in the cross section of the mixer barrel, the steel rods 401 of two adjacent urea breakers 4 are arranged in cross in the cross section of the mixer barrel, and the two urea breakers can be seen in sequence in the schematic view of Figure 7

[0027] ​​​The traditional wire mesh mixer has high resistance of the wire mesh, so that the exhaust back pressure is high when processing large displacement diesel engines. In order to adapt to the new emission standard, two groups of mixers may be needed for large displacement diesel engines above 4L, which further increases the back pressure and affects the running efficiency and power of the engine.

[0028] In the utility model, the steel rods of the two adjacent urea breaking pieces are vertically arranged in the cross section of the mixer cylinder.

[0029] In one embodiment, the steel rods 401 of the two adjacent urea breaking pieces are vertically arranged in the cross section of the mixer cylinder.

[0030] In one embodiment, the diameter of the steel rod is 0.5-1mm for diesel engines below 4L, 1-2mm for diesel engines with displacement of 4L-10L, and 1-5mm for diesel engines above 10L. The diameter of the steel rod changes accordingly with the change of the displacement and the diameter of the mixing pipe, which ensures the strength and makes the back pressure and atomization reach a good state. In order to ensure the durability and resistance to ablation at high temperature, the steel rod in the embodiment is made of SUS310 or SUS316 with high strength and corrosion resistance.

[0031] See Figure 4 , 5 In one embodiment of the utility model, the steel rods 401 are arranged on the urea breaking piece 4 in one layer, and four urea breaking pieces 4 are arranged in the embodiment.

[0032] See Figure 6 , 7 , 8, in another embodiment of the utility model, two urea breaking pieces 4 are stacked together, the steel rods 401 on each urea breaking piece 4 are arranged in three layers, and the steel rods 401 in different layers are staggered. By staggering the arrangement of the steel rods 401 and the multi-layer design, the back pressure is further reduced. Each steel rod has a height difference, the flow area is further expanded in the same plane, the height is used to cut and atomize the urea droplets, and the airflow is more uniformly distributed when passing through the mixer, which reduces the local resistance of the airflow and reduces the overall exhaust back pressure. The multi-layer steel rod design makes the airflow flow in layers when passing through the mixer, and the resistance of each layer of steel rod to the airflow is small, which reduces the overall exhaust back pressure. The staggered arrangement of the steel rods in different layers makes the airflow resistance uniformly distributed in the mixer, avoiding the formation of local high resistance area.

[0033] In one embodiment, in order to more simply install the urea breaking piece, the urea breaking piece 4 is provided with a ring body 402 which has the same size as the mixing pipe, and the two ends of the steel rod 401 are connected to the ring body 402, respectively, and the corresponding mixing pipe 3 is provided with a plurality of sections, and the urea breaking piece 4 is arranged between two adjacent sections of the mixing pipe 3, and the ring body 402 of the urea breaking piece 4 is welded to the pipe wall of the mixing pipe 3 to form a pipe body of the mixing pipe 3 which has a consistent diameter.

[0034] In one embodiment, the top of the mixing pipe 3 is provided with a variable-diameter step portion 303, and the upper end of the variable-diameter step portion 303 is provided with an opening 304 which is arranged towards the urea nozzle mounting seat 6, and the urea nozzle is mounted on the urea nozzle mounting seat 6.

[0035] In one embodiment, the air inlet includes a main air inlet 301A and an auxiliary air inlet 301B, and the main air inlet 301A is formed by windowing the pipe wall of the upper half of the mixing pipe, and the main air inlets 301A are arranged at intervals around the pipe wall of the mixing pipe 3, and the variable-diameter step portion 303 is provided with a guide vane 305, and the auxiliary air inlet 301B is arranged on the variable-diameter step portion 303, and the design of the main air inlet and the auxiliary air inlet realizes multi-channel air inlet, reduces the resistance of a single flow channel, reduces the air inlet back pressure, and the main air inlets are arranged at intervals around the pipe wall of the mixing pipe, so as to ensure that the airflow entering the mixer generates a cyclone, and to provide airflow conditions for urea atomization, the airflow is introduced from the auxiliary air inlet, and a negative pressure environment is further formed, which is helpful for the suction and atomization of urea droplets and prevents urea crystallization.

[0036] In one embodiment, the lower half of the mixing pipe 3 is provided with an air outlet 302 which is arranged on the side towards the baffle 2, and the air outlet 302 is arranged as a plurality of strip-shaped small windows arranged along the pipe wall of the mixing pipe 3, so as to ensure that the treated exhaust gas can be smoothly discharged, reduce the exhaust back pressure, and the strip-shaped small window design reduces the generation of turbulence at the air outlet, and the exhaust gas mixed with urea can be smoothly discharged, and the mixed airflow of the exhaust gas and the urea can be uniformly distributed in the subsequent SCR system, thereby improving the exhaust gas treatment efficiency.

[0037] In the embodiment, the arrangement of the air inlet and the air outlet improves the overall performance of the mixer, makes the urea atomization and mixing more efficient, and improves the overall treatment effect of the exhaust gas aftertreatment system.

[0038] The mixer can solve the problem of excessive back pressure of the traditional wire mesh mixer in the application of large-displacement diesel engines, the urea breaking piece with a steel rod structure greatly reduces the exhaust back pressure, ensures the efficient operation of the aftertreatment system, can improve the combustion efficiency of the engine, reduces fuel consumption, and meets the strict emission standards such as Euro 7.

[0039] In the embodiment of the utility model, a tail gas aftertreatment system is also provided, which comprises the urea mixer in the above embodiment.

[0040] In addition, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A urea mixer, comprising a mixer cylinder, a baffle plate disposed within the mixer cylinder, the baffle plate dividing the mixer cylinder into front and rear parts, a mixing pipe mounting portion formed by bending on the baffle plate, a mixing pipe mounted on the mixing pipe mounting portion, the upper half of the mixing pipe located on the front side of the baffle plate, the lower half of the mixing pipe extending through the baffle plate to the rear side of the baffle plate, the top of the mixing pipe connected to a urea nozzle mounting seat, and an air inlet and an air outlet respectively provided on the upper and lower halves of the mixing pipe, characterized in that: The mixing tube is provided with urea breaking elements, the urea breaking elements are arranged in two or more along the radial direction of the mixing tube, the steel rods of the urea breaking elements are arranged in cross in the cross section of the mixing tube.

2. A urea mixer according to claim 1, characterized in that: The steel rods are provided with a layer on the urea breaking elements.

3. A urea mixer according to claim 1, characterized in that: The steel rods are provided with multiple layers on the urea breaking elements, the steel rods of different layers are staggered.

4. A urea mixer according to claim 1, characterized in that: The urea breaking elements comprise ring bodies with the same size as the mixing tube, and the two ends of the steel rods are connected to the ring bodies.

5. A urea mixer according to claim 4, characterised in that: The mixing tube is provided with multiple sections, and the urea breaking elements are arranged between the two adjacent sections, and the ring bodies of the urea breaking elements are welded to the wall of the mixing tube.

6. A urea mixer according to claim 4, wherein: The top of the mixing tube is provided with a variable diameter step, the upper end of the variable diameter step is provided with an opening, the opening is arranged towards the urea nozzle mounting seat, and the urea nozzle is mounted on the urea nozzle mounting seat.

7. A urea mixer according to claim 6, characterised in that: The air inlet comprises a main air inlet and an auxiliary air inlet, the main air inlet is formed by windowing the wall of the upper half of the mixing tube, the main air inlets are arranged in intervals around the wall of the mixing tube, and the main air inlets are further provided with guide vanes, the auxiliary air inlet is arranged on the variable diameter step, the lower half of the mixing tube is provided with the air outlet towards one side of the baffle, the air outlet is arranged as multiple strip-shaped small windows arranged along the wall of the mixing tube, the bottom of the mixing tube is connected to a plug cover, and the plug cover is welded to the cylinder mixer.

8. A urea mixer according to claim 1, characterized in that: The steel rods of the two adjacent urea breaking elements are arranged in vertical in the cross section of the mixing tube.

9. A urea mixer according to claim 1, characterized in that: When the mixer is used in the aftertreatment system of diesel engines below 4L, the diameter of the steel rods is 0.5mm-1mm; when the mixer is used in the aftertreatment system of diesel engines of 4L-10L, the diameter of the steel rods is 1mm-2mm; and when the mixer is used in the aftertreatment system of diesel engines above 10L, the diameter of the steel rods is 1mm-5mm.

10. An exhaust gas aftertreatment system characterized by: The urea mixer comprises the urea mixer of any one of claims 1-9.

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