Preceding-stage mixing pipe assembly and tail gas aftertreatment device

Abstract

A forestage mixing tube assembly includes an outer housing, a first baffle, a second baffle, and a mixing tube. The outer shell comprises a first cavity, a second cavity and a third cavity. The first baffle is provided with a plurality of first communicating holes communicating with the first cavity and the second cavity. And the second baffle is provided with a plurality of second communicating holes for communicating the second cavity with the third cavity. The mixing pipe is provided with a first end part, a second end part and a pipe wall; the first end is fixed to the first baffle, the second end is fixed to the second baffle, and the pipe wall is provided with an inner cavity communicated with the first cavity. Compared with the prior art, the preceding-stage mixing pipe assembly can enable air flow to flow in layer, so that the distribution of a flow field is improved, the uniformity of the air flow is improved, and the back pressure is reduced. The utility model further discloses a tail gas after-treatment device comprising the preceding-stage mixing pipe assembly.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of front-stage mixing pipe assemblies and exhaust gas aftertreatment device, belong to engine exhaust gas aftertreatment technical field. BACKGROUND

[0002] In order to meet the higher regulatory emission requirements, a urea double-injection aftertreatment solution is proposed in the related art, which includes a front-stage aftertreatment assembly, a rear-stage aftertreatment assembly, a front-stage urea injection assembly, and a rear-stage urea injection assembly. The front-stage aftertreatment assembly includes a front-stage selective catalytic reducer. The rear-stage aftertreatment assembly includes a rear-stage diesel oxidation catalyst, a rear-stage diesel particulate filter located downstream of the rear-stage diesel oxidation catalyst, and a rear-stage selective catalytic reducer located downstream of the rear-stage diesel particulate filter. The rear-stage urea injection assembly includes a rear-stage urea nozzle located between the rear-stage diesel particulate filter and the rear-stage selective catalytic reducer. The front-stage urea injection assembly is provided with a front-stage urea nozzle located upstream of the front-stage selective catalytic reducer. SUMMARY

[0003] The utility model aims at providing a front-stage mixing pipe assembly and exhaust gas aftertreatment device with improved structure.

[0004] To achieve the above-mentioned purpose, the utility model adopts the following technical scheme: a front-stage mixing pipe assembly includes an outer shell, a first baffle installed in the outer shell, a second baffle installed in the outer shell and spaced apart from the first baffle, and a mixing pipe fixed between the first baffle and the second baffle. The outer shell includes a first cavity located on one side of the first baffle and away from the second baffle, a second cavity located between the first baffle and the second baffle, and a third cavity located on one side of the second baffle and away from the first baffle. The front-stage mixing pipe assembly further includes a front-stage urea nozzle configured to be installed on the outer shell, which is configured to inject atomized urea droplets into the first cavity. The first baffle is provided with a plurality of first communication holes communicating the first cavity and the second cavity, and the second baffle is provided with a plurality of second communication holes communicating the second cavity and the third cavity. The mixing pipe is provided with a first end, a second end opposite to the first end, and a pipe wall connecting the first end and the second end. The first end is fixed to the first baffle, the second end is fixed to the second baffle, and the pipe wall is provided with an inner cavity communicating with the first cavity.

[0005] As a further improved technical scheme of the present application, the first baffle is provided with a first mounting hole and a first flange portion at the periphery of the first mounting hole, and the first end portion of the mixing pipe is at least partially inserted into the first flange portion so as to connect the inner cavity with the first cavity.

[0006] As a further improved technical scheme of the present application, the first end portion of the mixing pipe is welded and fixed with the first flange portion.

[0007] As a further improved technical scheme of the present application, the second baffle is provided with a recessed portion and a shielding wall at the bottom of the recessed portion, and the second end portion of the mixing pipe is at least partially protruded into the recessed portion.

[0008] As a further improved technical scheme of the present application, the recessed portion is provided with a side wall connected with the shielding wall, and the second end portion of the mixing pipe is at least partially inserted into the side wall and fixed with the side wall.

[0009] As a further improved technical scheme of the present application, the shielding wall is not provided with any perforation.

[0010] As a further improved technical scheme of the present application, the mixing pipe is provided with a plurality of airflow perforations penetrating through the pipe wall, and the airflow perforations connect the inner cavity with the second cavity.

[0011] As a further improved technical scheme of the present application, the mixing pipe is provided with an airflow opening penetrating through the pipe wall, and the airflow opening connects the inner cavity with the second cavity.

[0012] As a further improved technical scheme of the present application, the shell body comprises a first shell and a second shell, the first shell and the second shell are separately arranged and welded and fixed together, the first shell is conical, the second shell is cylindrical, and the first baffle and the second baffle are welded and fixed on the inner wall of the second shell.

[0013] The present application also discloses a tail gas aftertreatment device, which comprises a front-stage mixing pipe assembly, a front-stage aftertreatment assembly, a rear-stage aftertreatment assembly and a rear-stage urea injection assembly, wherein the front-stage aftertreatment assembly comprises a front-stage selective catalytic reducer; the rear-stage aftertreatment assembly comprises a rear-stage diesel oxidation catalyst, a rear-stage diesel particulate filter located downstream of the rear-stage diesel oxidation catalyst and a rear-stage selective catalytic reducer located downstream of the rear-stage diesel particulate filter; the rear-stage urea injection assembly comprises a rear-stage urea nozzle located between the rear-stage diesel particulate filter and the rear-stage selective catalytic reducer; the front-stage mixing pipe assembly is the aforementioned front-stage mixing pipe assembly, and a front-stage urea nozzle is located upstream of the front-stage selective catalytic reducer.

[0014] Compared with the prior art, the front-stage mixing pipe assembly and the tail gas aftertreatment device can make the airflow flow in layers, thereby improving the flow field distribution, improving the airflow uniformity, and reducing the back pressure. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a principle diagram of the tail gas aftertreatment device of the utility model;

[0016] Figure 2 is Figure 1 a front-stage mixing pipe assembly in one embodiment of the utility model is a perspective schematic diagram from one angle;

[0017] Figure 3 is Figure 2 a perspective exploded view from another angle;

[0018] Figure 4 is Figure 3 a perspective exploded view from another angle;

[0019] Figure 5 is Figure 2 a cross-sectional schematic diagram along the line A-A in the front-stage mixing pipe assembly. DETAILED DESCRIPTION

[0020] The specific embodiments of the utility model will be described in detail below in combination with the drawings, wherein if there are several specific embodiments, the features in these embodiments can be combined with each other in the case of no conflict. When the description refers to the drawings, the same numbers or symbols in different drawings represent the same or similar elements unless otherwise specified. The content described in the following exemplary specific embodiments does not represent all the embodiments of the utility model, but rather, they are only examples of the products consistent with the utility model as recited in the claims of the utility model.

[0021] The terms used in the utility model are merely for the purpose of describing the specific embodiments, and are not intended to limit the protection scope of the utility model. It should be understood that the terms such as "first", "second", and the like used in the specification and claims of the utility model do not represent any order, quantity, or importance, but are only used for naming the features.

[0022] Please refer to Figure 1As shown, this utility model discloses an exhaust gas aftertreatment device, which includes: a pre-stage mixing pipe assembly 10, a pre-stage aftertreatment assembly 20, a post-stage aftertreatment assembly 40, and a post-stage urea injection assembly 30, wherein the pre-stage aftertreatment assembly 20 includes a pre-stage selective catalytic reduction (SCR) 21; the post-stage aftertreatment assembly 40 includes a post-stage diesel oxidation catalyst 41, a post-stage diesel particulate filter 42 located downstream of the post-stage diesel oxidation catalyst 41, and a post-stage selective catalytic reduction (SCR) 43 located downstream of the post-stage diesel particulate filter 42; the post-stage urea injection assembly 30 includes a post-stage urea nozzle 31 located between the post-stage diesel particulate filter 42 and the post-stage selective catalytic reduction (SCR) 43; the pre-stage mixing pipe assembly 10 includes a pre-stage urea nozzle 11, which is located upstream of the pre-stage selective catalytic reduction (SCR) 21.

[0023] Please combine Figures 2 to 5 As shown in the illustrated embodiment of this utility model, the pre-stage mixing tube assembly 10 includes a housing 12, a first baffle 13 installed in the housing 12, a second baffle 14 installed in the housing 12 and spaced apart from the first baffle 13, and a mixing tube 15 fixed between the first baffle 13 and the second baffle 14.

[0024] The outer shell 12 includes a first cavity 121 located on one side of the first baffle 13 and away from the second baffle 14, a second cavity 122 located between the first baffle 13 and the second baffle 14, and a third cavity 123 located on one side of the second baffle 14 and away from the first baffle 13.

[0025] In the embodiment illustrated in this utility model, the outer shell 12 includes a first shell 16 and a second shell 17, which are separately disposed and welded together. The first shell 16 is conical, and the second shell 17 is cylindrical. The first baffle 13 and the second baffle 14 are both welded to the inner wall of the second shell 17.

[0026] The pre-stage urea nozzle 11 is mounted on the first housing 16 of the outer housing 12, and the pre-stage urea nozzle 11 is configured to spray atomized urea droplets into the first cavity 121.

[0027] In the embodiment illustrated in this utility model, the first baffle 13 is provided with a plurality of first connecting holes 130 connecting the first cavity 121 and the second cavity 122. The second baffle 14 is provided with a plurality of second connecting holes 140 connecting the second cavity 122 and the third cavity 123.

[0028] The mixing tube 15 is generally cylindrical, and has a first end 151, a second end 152 opposite to the first end 151, and a tube wall 153 connecting the first end 151 and the second end 152. The first end 151 is fixed to the first baffle 13, the second end 152 is fixed to the second baffle 14, and the tube wall 153 has an inner cavity 150 communicating with the first cavity 121. In other words, in the embodiment illustrated in this utility model, the second cavity 122 is annular and surrounds the mixing tube 15.

[0029] Specifically, in the embodiment illustrated in this utility model, the first baffle 13 is provided with a first mounting hole 131 and a first flange portion 132 located around the first mounting hole 131. The first end portion 151 of the mixing tube 15 is at least partially inserted into the first flange portion 132, so that the inner cavity 150 communicates with the first cavity 121. In one embodiment of this utility model, the first end portion 151 of the mixing tube 15 is welded and fixed to the first flange portion 132. The first flange portion 132 is integrally stamped from the first baffle 13.

[0030] The second baffle 14 has a recess 141 and a shielding wall 142 located at the bottom of the recess 141. The second end 152 of the mixing tube 15 at least partially protrudes into the recess 141. Specifically, the recess 141 has a sidewall 143 connected to the shielding wall 142, and the second end 152 of the mixing tube 15 is at least partially inserted into and fixed to the sidewall 143. In the embodiment illustrated in this utility model, the shielding wall 142 is a complete wall, that is, it does not have any perforations.

[0031] The mixing tube 15 is provided with a plurality of airflow perforations 1531 penetrating the tube wall 153, the airflow perforations 1531 connecting the inner cavity 150 and the second cavity 122. In addition, the mixing tube 15 is also provided with an airflow opening 1532 penetrating the tube wall 153, the airflow opening 1532 connecting the inner cavity 150 and the second cavity 122.

[0032] In use, the engine exhaust gas enters the first chamber 121; when the injection conditions are met, the pre-stage urea nozzle 11 sprays atomized urea droplets into the first chamber 121; at this time, the engine exhaust gas and urea droplets form a mixed airflow; part of this mixed airflow passes through the first connecting hole 130 and enters the second chamber 122, and another part of the mixed airflow enters the inner chamber 150 of the mixing tube 15 from the first mounting hole 131; the mixed airflow mixes in the second chamber 122, and a portion of the mixed airflow passes through the airflow perforation 1531 and / or the airflow opening 1532 under the obstruction of the shielding wall 142 and enters the second chamber 122. The airflow entering the second chamber 122 can heat and / or insulate the mixing tube 15. With this configuration, the pre-stage mixing tube assembly 10 of this invention can make the heat exchange between the exhaust gas and urea droplets more complete, thereby improving the ability to resist urea crystallization and improving the uniformity of ammonia gas. Then, the airflow passes through the second connecting hole 140 to enter the third cavity 123.

[0033] Compared with the prior art, the pre-mixing pipe assembly 10 and the exhaust gas aftertreatment device of this utility model can make the airflow flow in layers, thereby improving the flow field distribution, while improving the airflow uniformity and reducing back pressure.

[0034] The above embodiments are only used to illustrate the present utility model and are not intended to limit the technical solutions described in the present utility model. The understanding of this specification should be based on those skilled in the art. Although the present utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still make modifications or equivalent substitutions to the present utility model. All technical solutions and improvements that do not depart from the spirit and scope of the present utility model should be covered within the scope of the claims of the present utility model.

Claims

1. A pre-mixing tube assembly, characterized in that, The assembly includes an outer casing, a first baffle installed within the outer casing, a second baffle installed within the outer casing and spaced apart from the first baffle, and a mixing tube fixed between the first baffle and the second baffle. The outer casing includes a first cavity located on one side of the first baffle and away from the second baffle, a second cavity located between the first baffle and the second baffle, and a third cavity located on one side of the second baffle and away from the first baffle. The pre-stage mixing tube assembly further includes a pre-stage urea nozzle configured to be installed on the outer casing, the pre-stage urea nozzle being configured to spray atomized urea droplets into the first cavity. The first baffle has a plurality of first connecting holes connecting the first cavity and the second cavity, and the second baffle has a plurality of second connecting holes connecting the second cavity and the third cavity. The mixing tube has a first end, a second end opposite to the first end, and a tube wall connecting the first end and the second end. The first end is fixed to the first baffle, the second end is fixed to the second baffle, and the tube wall has an inner cavity communicating with the first cavity.

2. The pre-mixing tube assembly as described in claim 1, characterized in that: The first baffle is provided with a first mounting hole and a first flange located around the first mounting hole. The first end of the mixing tube is at least partially inserted into the first flange, so that the inner cavity is connected to the first cavity.

3. The pre-mixing tube assembly as described in claim 2, characterized in that: The first end of the mixing tube is welded and fixed to the first flange.

4. The pre-mixing tube assembly as described in claim 1, characterized in that: The second baffle has a recess and a shielding wall at the bottom of the recess, and the second end of the mixing tube protrudes at least partially into the recess.

5. The pre-mixing tube assembly as described in claim 4, characterized in that: The recessed portion is provided with a sidewall connected to the shielding wall, and the second end of the mixing tube is at least partially inserted into the sidewall and fixed to the sidewall.

6. The pre-mixing tube assembly as described in claim 4, characterized in that: The shielding wall has no perforations.

7. The pre-mixing tube assembly as described in claim 1, characterized in that: The mixing tube is provided with a plurality of airflow perforations penetrating the tube wall, and the airflow perforations connect the inner cavity and the second cavity.

8. The pre-mixing tube assembly as described in claim 1, characterized in that: The mixing tube is provided with an airflow opening that penetrates the tube wall, and the airflow opening connects the inner cavity and the second cavity.

9. The pre-mixing tube assembly as claimed in claim 1, characterized in that: The outer shell includes a first shell and a second shell, which are separately disposed and welded together. The first shell is conical and the second shell is cylindrical. The first baffle and the second baffle are both welded to the inner wall of the second shell.

10. A tail gas aftertreatment device, characterized in that, include: The system comprises a pre-stage mixing pipe assembly, a pre-stage aftertreatment assembly, a post-stage aftertreatment assembly, and a post-stage urea injection assembly, wherein the pre-stage aftertreatment assembly includes a pre-stage selective catalytic reduction (SCR); the post-stage aftertreatment assembly includes a post-stage diesel oxidation catalyst, a post-stage diesel particulate filter located downstream of the post-stage diesel oxidation catalyst, and a post-stage selective catalytic reduction (SCR) located downstream of the post-stage diesel particulate filter; the post-stage urea injection assembly includes a post-stage urea nozzle located between the post-stage diesel particulate filter and the post-stage selective catalytic reduction (SCR); and the pre-stage mixing pipe assembly comprises the pre-stage mixing pipe assembly as described in any one of claims 1 to 9, wherein the pre-stage urea nozzle is located upstream of the pre-stage selective catalytic reduction (SCR).

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