End cover integrated mixer and corresponding exhaust system

Abstract

The mixer comprises an end cover shell, the end cover shell is provided with an open end, a closed end and a side wall, the open end is used for being connected with an SCR, a first open hole and a second open hole are independently formed in the side wall of the end cover shell, the first open hole is used for installing a nozzle, and the second open hole is an air inlet of the mixer. A mixing pipe and a partition plate are arranged in an inner cavity of the end cover shell, the inner cavity of the end cover shell is divided into a first cavity and a second cavity through the partition plate, an inlet of the mixing pipe is located in the first cavity, an outlet of the mixing pipe is located in the second cavity, and the part, corresponding to the first cavity, in the open end of the end cover shell is closed. The part, corresponding to the second cavity, in the open end of the end cover shell is an air outlet of the mixer, a preset angle is formed between the longitudinal axis of the mixing pipe and the longitudinal axis of the end cover shell, and an arc plate is arranged below an outlet of the mixing pipe. The invention also relates to a corresponding exhaust system. The device is high in integration level, low in back pressure, good in mixing effect and excellent in anti-crystallization performance.

Description

Technical Field

[0001] The invention relates to the technical field of tail gas treatment, in particular to an end cover integrated mixer and a corresponding exhaust system. Background Art

[0002] With the continuous upgrading of domestic diesel vehicle emission regulations, more stringent requirements are put forward for automobile exhaust after-treatment systems and their core components, mixers. As a key component in the after-treatment system, the performance of the mixer directly affects NOx emissions.

[0003] The mixer needs to ensure that the exhaust gas and the reducing agent (such as urea aqueous solution) are fully mixed to improve the conversion efficiency of the SCR system. The mixer also needs to have good heat exchange performance to ensure that the urea aqueous solution is quickly vaporized and fully mixed with the exhaust gas during the injection process, which helps to improve the conversion efficiency of the SCR system and reduce urea consumption. Because the "National VI" standard has stricter emission restrictions under low temperature and low load conditions, and the injection volume increases, the risk of crystallization of the mixer increases. The generation of a large number of crystals will block the post-treatment channel, resulting in increased back pressure in the post-treatment system and insufficient vehicle power, and there is a risk of emissions exceeding regulatory limits.

[0004] The diesel engine regulations have been upgraded to National VII, and the urea dual injection system is one of the important solutions. Compared with the National VI exhaust after-treatment system, it is necessary to add urea injection at the entrance of the after-treatment system, and it is necessary to add a pre-stage mixer and SCR catalyst, which poses a greater challenge to the boundary of the after-treatment system. The general technical solution uses a simple mixer in the pre-exhaust pipe, which has many disadvantages: unsatisfactory mixing effect, high back pressure, easy urea crystallization and other problems.

[0005] In general, with the upgrade of regulations, the following problems still exist: the spatial layout of the pre-mixer and after-treatment system for National VII is challenging; the back pressure of the mixer and after-treatment system is high, resulting in poor engine fuel economy; the urea crystallization in the mixer and the mixing efficiency of urea and exhaust gas are low, and the De-NOx conversion efficiency is low. Summary of the invention

[0006] In view of the deficiencies of the existing prior art, the present invention provides an end cover integrated mixer and a corresponding exhaust system.

[0007] To achieve the above-mentioned object, the first aspect of the present invention provides an end cover integrated mixer, which has the following technical scheme: the end cover integrated mixer comprises an end cover shell, the end cover shell has an open end, a closed end opposite to the open end, and a side wall located between the open end and the closed end, the open end is used to connect the SCR, the first opening and the second opening are independently arranged on the side wall of the end cover shell, the first opening is used to install the nozzle, the second opening is the air inlet of the mixer, the inner cavity of the end cover shell is provided with a mixing tube and a partition, the mixing tube passes through the partition and is arranged in the inner cavity of the end cover shell, and the mixing tube is connected to the inner cavity of the end cover shell through the partition. The inner cavity of the end cover shell is divided into a first cavity and a second cavity, the mixing tube has an inlet for air intake and an outlet for air outlet, the inlet of the mixing tube is located in the first cavity, the outlet of the mixing tube is located in the second cavity, the part of the open end of the end cover shell corresponding to the first cavity is closed, and the part of the open end of the end cover shell corresponding to the second cavity is the air outlet of the mixer, so that the exhaust gas enters the first cavity through the air inlet of the mixer and enters the mixing tube through the inlet of the mixing tube, and is mixed with the reductant in the mixing tube, and then discharged through the outlet of the mixing tube and the air outlet of the mixer and enters the SCR,

[0008] The longitudinal axis of the mixing tube forms a preset angle with the longitudinal axis of the end cover shell, and the preset angle is 60° to 120°. An arc plate is arranged below the outlet of the mixing tube so that the mixed gas flowing out of the outlet of the mixing tube is discharged through the space between the outlet and the arc plate via the gas outlet.

[0009] Preferably, the nozzle is installed in the first opening via a nozzle mounting seat.

[0010] Preferably, central axes of the first opening and the second opening are perpendicular to the longitudinal axis of the end cover shell.

[0011] Preferably, the portion of the open end corresponding to the first cavity is closed by the partition.

[0012] Preferably, the partition has a plate body, the plate body is provided with a mounting hole, the mounting hole is used for the mixing tube to pass through, and the partition has an extension portion extending from the plate body toward the first cavity, and the portion of the open end corresponding to the first cavity is closed by the extension portion.

[0013] Preferably, at least one side of the arc plate has a concave channel, so that the mixed gas flowing out of the outlet of the mixing tube passes through the concave channel and is discharged through the gas outlet.

[0014] Preferably, the arc plate is provided with a plurality of third openings.

[0015] Preferably, the mixing tube includes a swirl tube with swirl blades inside, and a plurality of blade windows are arranged on the upper portion of the swirl tube. The plurality of blade windows form the inlet of the mixing tube, and the gas forms a rotating shape when entering the mixing tube through the blade windows. The bottom opening of the swirl tube is the outlet of the mixing tube.

[0016] A second aspect of the present invention provides an exhaust system, characterized in that it comprises an SCR and the mixer, wherein the mixer is installed on the SCR as an end cover.

[0017] The end cover integrated mixer and the corresponding exhaust system of the present invention utilize the end cone at the inlet of the existing post-processing system to integrate the mixer, which has high integration, compact space, low back pressure, good mixing effect and excellent anti-crystallization performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below.

[0019] Figure 1 It is a simplified diagram of the exhaust system of the present invention.

[0020] Figure 2 It is a schematic diagram of an explosion of the end cover integrated SCR mixer of the present invention.

[0021] Figure 3 It is a schematic diagram for explaining the working principle of the end cover integrated SCR mixer of the present invention.

[0022] Figure 4 It is a partial structural schematic diagram of the end cover integrated SCR mixer of the present invention.

[0023] Reference numerals

[0024] 1 partition; 101 first cavity; 102 second cavity; 2 mixing tube; 3 swirl blade; 4 arc plate; 5 end cover shell; 6 sealing plate; 7 nozzle seat; 8 end cover integrated SCR mixer; 9 SCR; 10 first opening; 11 second opening; 12 opening end. DETAILED DESCRIPTION

[0025] In order to more clearly describe the technical content of the present invention, it is further described below in conjunction with specific embodiments.

[0026] like Figure 1The figure is a schematic diagram of the exhaust system of the present invention. The exhaust system includes an SCR 9 and an end cover integrated SCR mixer 8, and the end cover integrated SCR mixer 8 is installed and connected to the SCR 9 as an end cover. The exhaust gas enters through the end cover integrated SCR mixer 8, and after mixing with the reducing agent sprayed by the nozzle and undergoing heat exchange, the mixed gas enters the SCR (Selective Catalytic Reduction) through the end cover integrated SCR mixer 8, and a reduction reaction occurs.

[0027] like Figures 2 to 4 As shown, it is a specific embodiment of the end cover integrated SCR mixer 8 of the present invention. The end cover integrated mixer 8 comprises an end cover shell 5, the end cover shell 5 has an open end 12, a closed end opposite to the open end, and a side wall between the open end and the closed end, the open end 12 is used to connect the SCR 9, the first opening 10 and the second opening 11 are independently arranged on the side wall of the end cover shell 5, the first opening 10 is used to install the nozzle, the second opening 11 is the air inlet of the mixer, the engine exhaust gas enters the mixer through the air inlet to mix with the reductant, the inner cavity of the end cover shell 5 is provided with a mixing tube 2 and a partition 1, the mixing tube 2 passes through the partition 1 and is arranged in the inner cavity of the end cover shell 5, as shown in FIG. Figure 3 As shown, the inner cavity of the end cover shell 5 is divided into a first cavity 101 and a second cavity 102 by the partition 1, the mixing tube 2 has an inlet for air intake and an outlet for air outlet, the inlet of the mixing tube 2 is located in the first cavity 101, the outlet of the mixing tube 2 is located in the second cavity 102, the part of the open end 12 of the end cover shell 5 corresponding to the first cavity 101 is closed, the part of the open end 12 of the end cover shell 5 corresponding to the second cavity 102 is the gas outlet of the mixer, and the mixed gas is discharged from the gas outlet, so that the exhaust gas enters the first cavity 101 through the air inlet of the mixer and enters the mixing tube 2 through the inlet of the mixing tube 2, and after mixing with the reducing agent in the mixing tube 2, it is discharged through the outlet of the mixing tube 2 and the gas outlet of the mixer and enters the SCR.

[0028] The end cover integrated SCR mixer provided by the present invention integrates the end cover of the package post-processing with the mixer components, and creatively integrates the air inlet and nozzle of the mixer independently on the side wall of the end cover shell. After the exhaust gas enters the inner cavity, it is mixed with the reductant in the mixing tube, and the open end of the end cover shell can be directly connected to the SCR. The present invention is the first to create a mixer structure with high integration and compact space, while having low back pressure and good mixing effect.

[0029] The nozzle is installed in the first opening 10 via the nozzle mounting seat 7. The first opening 10 is provided with a sealing plate 6 to mount the nozzle mounting seat 7, and the mixing tube 2 passes through the opening of the sealing plate 6 to enable the nozzle to spray the reducing agent into the mixing tube 2.

[0030] like Figures 2 to 3 As shown, the end cover shell 5 has a longitudinal axis, the longitudinal axis of the end cover shell 5 passes through the open end 12 and the closed end, and the longitudinal axis of the mixing tube 2 is perpendicular to the longitudinal axis of the end cover shell 5. The central axes of the first opening 10 and the second opening 11 are both perpendicular to the longitudinal axis of the end cover shell 5, and the first opening 10 and the second opening 11 are both arranged on the side wall of the end cover shell 5. The mixing tube 2 can also be arranged in the inner cavity of the end cover shell in a non-vertical state, for example, inclined at an angle between 60° and 120°.

[0031] like Figure 3 and Figure 4 As shown, the portion of the open end 12 corresponding to the first cavity 101 is closed by the partition 1.

[0032] Specifically, the partition 1 has a plate body, the plate body is provided with a mounting hole, the mounting hole is used for the mixing tube 2 to pass through, and the partition 1 has an extension portion extending from the plate body toward the first cavity 101, and the portion of the open end 12 corresponding to the first cavity 101 is closed by the extension portion.

[0033] like Figures 2 to 4 As shown, an arc plate 4 is arranged below the outlet of the mixing tube 2, and both sides of the arc plate 4 have concave channels, so that the mixed gas flowing out of the outlet of the mixing tube 2 is discharged through the concave channels and the gas outlet. The arc plate 4 used in this embodiment is generally bowl-shaped.

[0034] In this embodiment, the arc plate 4 is provided with a plurality of third openings. The high-temperature gas can enter the bottom of the arc plate through the third openings, remove the urea liquid film and urea crystals that may be gathered in the space between the bottom of the arc plate and the arc wall of the end cover shell 5, effectively improve the crystallization performance, and at the same time facilitate the evaporation of urea and the improvement of the mixing efficiency of ammonia.

[0035] like Figures 2 to 4As shown, the mixing tube 2 includes a swirl tube with swirl blades 3 inside, and a plurality of blade windows are arranged on the upper part of the swirl tube 2, and the plurality of blade windows form the inlet of the mixing tube 2. When the gas enters the mixing tube 2 through the blade opening, a swirl shape is formed, and the bottom opening of the swirl tube 2 is the outlet of the mixing tube 2. Based on the blade windows and swirl blades of the swirl tube, an efficient swirl is formed inside the end cover integrated SCR mixer of the present invention, and the performance is excellent. The side wall of the swirl tube can be perforated, and the blades in the blade windows can face inward or outward.

[0036] The end cover integrated SCR mixer and the corresponding exhaust system of the present invention utilize the end cone at the inlet of the existing post-treatment system to integrate the mixer, which has high integration, compact space, low back pressure, good mixing effect and excellent anti-crystallization performance.

[0037] In this specification, the present invention has been described with reference to specific embodiments thereof. However, it is apparent that various modifications and variations may be made without departing from the spirit and scope of the present invention. Therefore, the specification and drawings should be regarded as illustrative rather than restrictive.

Claims

1. An end cover integrated mixer, characterized in that: The invention comprises an end cover shell, wherein the end cover shell has an open end, a closed end opposite to the open end, and a side wall between the open end and the closed end, wherein the open end is used to connect the SCR, a first opening and a second opening are independently arranged on the side wall of the end cover shell, wherein the first opening is used to install a nozzle, and the second opening is an air inlet of the mixer, and a mixing tube and a partition are arranged in the inner cavity of the end cover shell, wherein the mixing tube passes through the partition and is arranged in the inner cavity of the end cover shell, and the inner cavity of the end cover shell is divided into a first cavity and a second cavity by the partition, and the mixing The mixing tube has an inlet for air intake and an outlet for air outlet, the inlet of the mixing tube is located in the first cavity, the outlet of the mixing tube is located in the second cavity, the part of the open end of the end cover shell corresponding to the first cavity is closed, and the part of the open end of the end cover shell corresponding to the second cavity is the outlet of the mixer, so that the exhaust gas enters the first cavity through the inlet of the mixer and enters the mixing tube through the inlet of the mixing tube, and after mixing with the reducing agent in the mixing tube, it is discharged through the outlet of the mixing tube and the outlet of the mixer and enters the SCR; The longitudinal axis of the mixing tube forms a preset angle with the longitudinal axis of the end cover shell, and the preset angle is 60° to 120°. An arc plate is arranged below the outlet of the mixing tube so that the mixed gas flowing out of the outlet of the mixing tube is discharged through the space between the outlet and the arc plate via the gas outlet.

2. The end cover integrated mixer according to claim 1, characterized in that: The nozzle is installed in the first opening via a nozzle mounting seat.

3. The end cover integrated mixer according to claim 1, characterized in that: The central axes of the first opening and the second opening are both perpendicular to the longitudinal axis of the end cover shell.

4. The end cover integrated SCR mixer according to any one of claims 1 to 3, characterized in that: The portion of the open end corresponding to the first cavity is closed by the partition.

5. The end cover integrated mixer according to claim 4, characterized in that: The partition has a plate body, the plate body is provided with a mounting hole, the mounting hole is used for the mixing tube to pass through, the partition has an extension portion extending from the plate body toward the first cavity, and the portion of the open end corresponding to the first cavity is closed by the extension portion.

6. The end cover integrated mixer according to claim 1, characterized in that: At least one side of the arc plate has a concave channel, and the mixed gas flowing out from the outlet of the mixing tube passes through the concave channel and is discharged through the gas outlet.

7. The end cover integrated mixer according to claim 1, characterized in that: The arc plate is provided with a plurality of third openings.

8. The end cover integrated mixer according to claim 1, characterized in that: The mixing tube comprises a swirl tube with swirl blades inside. A plurality of blade windows are arranged on the upper part of the swirl tube. The plurality of blade windows form the inlet of the mixing tube. When the gas enters the mixing tube through the blade windows, a rotating shape is formed. The bottom end opening of the swirl tube is the outlet of the mixing tube.

9. An exhaust system, characterized in that: The invention comprises an SCR and the mixer according to any one of claims 1 to 8, wherein the mixer is installed on the SCR as an end cover.

Images