Cylinder type SCR (Selective Catalytic Reduction) mixer and corresponding post-processing system

Abstract

The utility model relates to a barrel-type SCR mixer which comprises a barrel-shaped shell, the barrel-shaped shell is provided with a first opening end and a second opening end, a first opening hole is formed in the side wall of the barrel-shaped shell, a mixing pipe and a partition plate assembly are arranged in an inner cavity of the barrel-shaped shell, and the mixing pipe penetrates through a first partition plate unit to be arranged in the inner cavity of the barrel-shaped shell. An inner cavity of the cylindrical shell is divided into a first cavity body and a second cavity body through the first partition plate unit, the second partition plate unit is used for sealing the part, corresponding to the second cavity body, in the first open end, and the part, corresponding to the first cavity body, in the first open end is an air inlet of the cylindrical SCR mixer. The third partition plate unit is used for sealing the part, corresponding to the first cavity, of the second open end, the part, corresponding to the second cavity, of the second open end is an air outlet of the barrel type SCR mixer, an inlet of the mixing pipe is located in the first cavity, and an outlet of the mixing pipe is located in the second cavity. The utility model also relates to a corresponding post-processing system. The mixing effect is good, and the anti-crystallization performance is excellent.

Description

TECHNICAL FIELD

[0001] The utility model relates to tail gas treatment technical field especially a kind of cylinder type SCR mixer and corresponding aftertreatment system. BACKGROUND

[0002] With the continuous upgrading of domestic diesel vehicle emission regulations, more stringent requirements are put forward for automobile exhaust aftertreatment system and its core component mixer. As a key component in the aftertreatment system, the performance of the mixer directly affects the emission of NOx.

[0003] The mixer needs to ensure that the exhaust gas and the reducing agent (such as urea 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 solution is rapidly 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. Due to the stricter emission limits of "China VI" standard under low temperature and low load conditions, and the increase of injection amount, the risk of crystallization of the mixer increases. The generation of a large amount of crystallization will block the aftertreatment channel, causing the back pressure of the aftertreatment system to rise, the vehicle power to be insufficient, and the risk of emission exceeding the regulatory limits.

[0004] Therefore, the existing mixer and aftertreatment system still have the following problems: high back pressure of the mixer and aftertreatment system, leading to poor engine fuel economy; urea crystallization in the mixer; low mixing efficiency of urea and exhaust gas, and low De-NOx conversion efficiency. SUMMARY

[0005] In view of the deficiencies of the existing technology, the utility model provides a cylinder type SCR mixer and corresponding aftertreatment system.

[0006] To achieve the above object, the utility model discloses a first aspect provides a kind of barrel type SCR mixers, with following technical solutions: including cylindrical shell, the cylindrical shell has first open end, with the second open end opposite to the first open end, first aperture is arranged on the lateral wall of the cylindrical shell, the first aperture is used to install nozzle, the inner chamber of the cylindrical shell is provided with mixing pipe, baffle assembly, the baffle assembly includes first baffle unit, second baffle unit and third baffle unit, the mixing pipe is arranged in the inner chamber of the cylindrical shell by the first baffle unit, the inner chamber of the cylindrical shell is separated into first cavity and second cavity by the first baffle unit, the second baffle unit is used to close the portion corresponding to the second cavity in the first open end, the portion corresponding to the first cavity in the first open end is the gas inlet of the barrel type SCR mixer, the third baffle unit is used to close the portion corresponding to the first cavity in the second open end, the portion corresponding to the second cavity in the second open end is the gas outlet of the barrel type SCR mixer, the mixing pipe has inlet for gas and outlet for gas, the inlet of the mixing pipe is located in the first cavity, the outlet of the mixing pipe is located in the second cavity, so that tail gas enters the first cavity through the gas inlet of the mixer, enters the inside of the mixing pipe through the inlet of the mixing pipe to mix with the reducing agent sprayed by the nozzle, and from the outlet of the mixing pipe into the second cavity, exhaust through the gas outlet of the mixer.

[0007] Preferably, the baffle assembly includes a front baffle and a rear baffle, the front baffle includes a front baffle body and a front extension extending from the front baffle body towards the second cavity, the rear baffle includes a rear baffle body and a rear extension extending from the rear baffle body towards the first cavity, the front baffle body and the rear baffle body combine to form the first baffle unit, the first baffle unit has a mounting hole for the mixing pipe to pass through, the front extension forms the second baffle unit, and the rear extension forms the third baffle unit.

[0008] Preferably, the front baffle and the rear baffle each have an L-shaped profile.

[0009] Preferably, an edge of the gas outlet is provided with a gas baffle, the gas baffle closes an edge portion of the gas outlet, so that mixed gas is discharged through an area of the gas outlet that is not closed by the gas baffle.

[0010] Preferably, the gas baffle is provided with a plurality of second apertures, so that mixed gas is discharged through the area of the gas outlet that is not closed by the gas baffle and the second apertures.

[0011] Preferably, the longitudinal axis of the mixing tube is at a preset angle of 60°-120° with the longitudinal axis of the cylindrical shell.

[0012] Preferably, the central axis of the first opening is perpendicular to the longitudinal axis of the cylindrical shell.

[0013] Preferably, the outer side of the cylindrical shell is provided with heat insulation cotton and a heat insulation cover.

[0014] Preferably, the mixing tube comprises a cyclone tube, the upper part of the cyclone tube is provided with a plurality of vane windows, the plurality of vane windows form the inlet of the mixing tube, and the gas enters the mixing tube through the vane windows to form a rotating mode, the bottom opening of the cyclone tube is the outlet of the mixing tube; the nozzle is installed in the first opening through a nozzle mounting seat.

[0015] Preferably, the inside of the cyclone tube is provided with cyclone vanes or a wire mesh.

[0016] The second aspect of the utility model provides a kind of post-processing system, its main features are, including the cylindrical SCR mixer, the first opening end of the cylindrical SCR mixer is sequentially connected with DPF, DOC, the second opening end of the cylindrical SCR mixer is connected with SCR or ASC, the DOC is provided with gas inlet, and the SCR or ASC is with setting gas outlet, the longitudinal axis of the cylindrical SCR mixer coincides with the longitudinal axis of the post-processing system.

[0017] The cylindrical SCR mixer and the corresponding post-processing system of the utility model adopt cylindrical mixer, space is compact, back pressure is low, mixing effect is good, and crystallization prevention performance is excellent. BRIEF DESCRIPTION OF DRAWINGS

[0018] To more clearly illustrate the technical scheme in the embodiment of the utility model, the drawings needed in the embodiment are simply introduced as follows.

[0019] Figure 1 It is the structural schematic diagram of the post-processing system of the utility model.

[0020] Figure 2 It is the explosion schematic diagram of the cylindrical SCR mixer of the utility model.

[0021] Figure 3 It is the first visual angle schematic diagram of the working principle of the cylindrical SCR mixer of the utility model.

[0022] Figure 4 It is the second visual angle schematic diagram of the working principle of the cylindrical SCR mixer of the utility model. DETAILED DESCRIPTION

[0023] In order to enable the technical content of the utility model to be described more clearly, further description will be made below in combination with specific embodiments.

[0024] As Figure 1 shown, it is a principle schematic diagram of the aftertreatment system of the utility model. Wherein the aftertreatment system includes the barrel type SCR mixer 16, the first open end of the barrel type SCR mixer 16 is connected with DPF 15, DOC 14 in turn, the second open end of the barrel type SCR mixer 16 is connected with SCR 18 or ASC, the DOC 14 is connected with the intake subassembly 13 to set up gas inlet, the SCR 18 is connected with the exhaust subassembly 19 to set up gas outlet, the longitudinal axis of the barrel type SCR mixer 16 coincides with the longitudinal axis of the aftertreatment system, that is, the aftertreatment system is straight barrel type as a whole.

[0025] DPF 15, DOC 14, barrel type SCR mixer 16, SCR 18 can be connected through flange, clamp 20, welding and the like, form straight barrel type internal cavity. Specifically, DPF can be designed to be detachable. Wherein, DOC (Diesel Oxidation Catalyst) is diesel engine oxidation catalyst, DPF (Diesel Particulate Filter) is diesel particulate trap, SCR (Selective Catalytic Reduction) is selective catalytic reducer, ASC (Ammonia Slip Catalyst) is ammonia gas oxidation catalyst, DOC, DPF, SCR, ASC all contain catalyst carrier.

[0026] As Figure 1 shown, the exhaust gas enters the aftertreatment system through the intake subassembly 13, passes through DOC 14, DPF 15 in turn, enters the barrel type SCR mixer 16, mixes with the reducing agent sprayed by the nozzle 17 in the internal barrel type SCR mixer 16, enters SCR 18 to carry out catalytic reduction reaction, and the exhaust gas meeting the requirements is discharged through the exhaust subassembly 19.

[0027] As Figures 2 to 4The utility model discloses a barrel type SCR mixer 16, as shown in the specific embodiment of the barrel type SCR mixer 16. The barrel type SCR mixer 16 includes a cylindrical shell 5, the cylindrical shell 5 has a first open end, a second open end opposite the first open end, a first opening 9 is arranged on the lateral wall of the cylindrical shell 5, the first opening 9 is used to install the nozzle 17, the inner cavity of the cylindrical shell 5 is provided with a mixing pipe 2, a baffle assembly, the baffle assembly includes a first baffle unit, a second baffle unit and a third baffle unit, the mixing pipe 2 is arranged in the inner cavity of the cylindrical shell 5 through the first baffle unit, the inner cavity of the cylindrical shell 5 is divided into a first cavity and a second cavity through the first baffle unit, the second baffle unit is used to close the part corresponding to the second cavity in the first open end, the part corresponding to the first cavity in the first open end is the air inlet of the barrel type SCR mixer 16, that is, the part not closed by the second baffle unit in the first open end is the air inlet, the third baffle unit is used to close the part corresponding to the first cavity in the second open end, the part corresponding to the second cavity in the second open end is the air outlet of the barrel type SCR mixer, that is, the part not closed by the third baffle unit in the second open end is the air outlet. The mixing pipe 2 has an inlet for air and an outlet for air, the inlet of the mixing pipe 2 is located in the first cavity, and the outlet of the mixing pipe 2 is located in the second cavity.

[0028] The exhaust gas enters the first cavity through the air inlet of the mixer 16, enters the inside of the mixing pipe 2 through the inlet of the mixing pipe 2 to mix and exchange heat with the reducing agent sprayed by the nozzle 17, and enters the second cavity from the outlet of the mixing pipe 2, is discharged through the air outlet of the mixer 16, enters the rear-end SCR, and in the SCR, nitrogen oxide and ammonia gas occur reduction reaction. The nozzle 17 is installed in the first opening 9 through the nozzle mounting seat 7, the first opening 9 is provided with a sealing plate 6 to install the nozzle mounting seat 7, and the mixing pipe 2 passes through the opening of the sealing plate 6 to realize that the nozzle sprays the reducing agent into the mixing pipe 2.

[0029] As Figures 2 to 4As shown, the baffle assembly comprises a front baffle 1 and a rear baffle 4, the front baffle 1 comprises a front baffle body 11 and a front extension 22 extending from the front baffle body 11 towards the second cavity, the rear baffle 4 comprises a rear baffle body 21 and a rear extension 23 extending from the rear baffle body 21 towards the first cavity, the front baffle body 11 and the rear baffle body 21 combine to form the first baffle unit, the first baffle unit has a mounting hole, the front baffle body 11 and the rear baffle body 21 both have concave parts to fit together to form the mounting hole, the mounting hole is used for the mixing pipe 2 to pass through, the front extension 22 forms the second baffle unit, as shown in Figure 3 As shown, the front extension 22 closes the part of the first open end corresponding to the second cavity, the rear extension 23 forms the third baffle unit, as shown in Figure 4 As shown, the rear extension 23 closes the part of the second open end corresponding to the first cavity.

[0030] As shown in Figure 2 The front baffle 1 and the rear baffle 4 both have an L-shaped profile. The front baffle 1 and the rear baffle 4 are assembled to form a baffle assembly with a first baffle unit, a second baffle unit and a third baffle unit.

[0031] As shown in Figure 2 And Figure 4 As shown, the edge of the gas outlet is provided with a gas baffle 8, the gas baffle 8 closes the edge part of the gas outlet, so that the mixed gas is discharged through the area of the gas outlet which is not closed by the gas baffle, which can effectively adjust the gas uniformity index and ammonia uniformity index of the SCR end face, and can effectively prevent urea liquid or crystals from passing through the mixer part from the bottom to the SCR end face to block the SCR catalyst.

[0032] The gas baffle 8 can be provided with a plurality of second openings, so that the mixed gas is discharged through the area of the gas outlet which is not closed by the gas baffle and the second openings, to adjust the gas and ammonia distribution uniformity index.

[0033] In the cylindrical SCR mixer 16 of the utility model, the longitudinal axis of the mixing pipe 2 is perpendicular to the longitudinal axis of the cylindrical shell. The mixing pipe 2 can also be arranged in a non-perpendicular state in the inner cavity of the cylindrical shell 5, for example, inclined at an angle between 60° and 120°. The central axis of the first opening 9 is perpendicular to the longitudinal axis of the cylindrical shell 5.

[0034] As shown in Figure 2 The outer side of the cylindrical shell 5 is provided with heat insulation cotton 12 and a heat shield 10. The heat insulation cotton 12 and the heat shield 10 are both formed by two petals.

[0035] AsFigure 2 and Figure 3 As shown in the figure, the mixing pipe 2 comprises a cyclone pipe, the upper part of the cyclone pipe is provided with a plurality of vane windows, the plurality of vane windows form the inlet of the mixing pipe 2, the gas enters the mixing pipe through the vane windows to form a rotating mode, and the bottom opening of the cyclone pipe is the outlet of the mixing pipe 2. The vane of the vane window can be at an angle, which can be outward or inward.

[0036] The inside of the cyclone pipe is provided with a wire mesh, which can increase the breaking of the reducing agent droplets, is beneficial to the evaporation of the urea solution into ammonia gas, and can also be provided with a cyclone vane. The height direction of the cyclone vane can be parallel to the axis of the cyclone pipe or there is an included angle, and the included angle can be 0-80 degrees. The cyclone vane can be selected to be provided with a groove structure to improve the rotating effect of the airflow and reduce the turbulent flow.

[0037] The cylinder type SCR mixer and the corresponding aftertreatment system adopt the cylinder type mixer, are compact in space, low in back pressure, good in mixing effect, and excellent in crystallization prevention performance.

[0038] In this specification, the utility model has been described with reference to its specific embodiments. However, it is obvious that various modifications and changes can still be made without departing from the spirit and scope of the utility model. Therefore, the specification and drawings should be considered as illustrative rather than restrictive.

Claims

1. A barrel-type SCR mixer characterized by, The cylinder shell has a first open end, a second open end opposite to the first open end, and a first opening in the side wall of the cylinder shell for mounting a nozzle, and an inner cavity of the cylinder shell is provided with a mixing pipe and a baffle assembly, the baffle assembly includes a first baffle unit, a second baffle unit and a third baffle unit, the mixing pipe is arranged in the inner cavity of the cylinder shell through the first baffle unit, the inner cavity of the cylinder shell is divided into a first cavity and a second cavity by the first baffle unit, the second baffle unit is used for closing a part of the first open end corresponding to the second cavity, a part of the first open end corresponding to the first cavity is an air inlet of the cylinder SCR mixer, the third baffle unit is used for closing a part of the second open end corresponding to the first cavity, and a part of the second open end corresponding to the second cavity is an air outlet of the cylinder SCR mixer, the mixing pipe has an inlet for air and an outlet for air, the inlet of the mixing pipe is located in the first cavity, and the outlet of the mixing pipe is located in the second cavity, so that the exhaust gas enters the first cavity through the air inlet of the mixer, enters the inside of the mixing pipe through the inlet of the mixing pipe to mix with the reducing agent sprayed by the nozzle, and is discharged through the outlet of the mixing pipe into the second cavity and then through the air outlet of the mixer.

2. The drum SCR mixer of claim 1, wherein, The baffle assembly includes a front baffle and a rear baffle, the front baffle includes a front baffle body and a front extension part extending from the front baffle body towards the second cavity, the rear baffle includes a rear baffle body and a rear extension part extending from the rear baffle body towards the first cavity, the front baffle body and the rear baffle body combine to form the first baffle unit, the first baffle unit has a mounting hole for the mixing pipe to pass through, the front extension part forms the second baffle unit, and the rear extension part forms the third baffle unit.

3. The drum SCR mixer of claim 2, wherein, The front baffle and the rear baffle both have an L-shaped profile.

4. The cartridge SCR mixer of claim 1, wherein, An air outlet baffle is arranged at the edge of the air outlet, the air outlet baffle closes the edge part of the air outlet, so that the mixed gas is discharged through the area of the air outlet which is not closed by the air outlet baffle.

5. The drum SCR mixer of claim 4, wherein, The air outlet baffle is provided with a plurality of second openings, so that the mixed gas is discharged through the area of the air outlet which is not closed by the air outlet baffle and the second openings.

6. The cartridge SCR mixer of claim 1, wherein, A longitudinal axis of the mixing pipe and a longitudinal axis of the cylinder shell form a preset angle, the preset angle is 60°-120°, and a central axis of the first opening is perpendicular to the longitudinal axis of the cylinder shell.

7. The cartridge SCR mixer of claim 1, wherein, Heat insulation cotton and a heat insulation cover are arranged outside the cylinder shell.

8. The cartridge SCR mixer of claim 1, wherein, The mixing pipe comprises a cyclone pipe, the upper part of the cyclone pipe is provided with a plurality of vane windows, the vane windows form the inlet of the mixing pipe, and gas enters the mixing pipe through the vane windows to form a rotating mode, and the bottom opening of the cyclone pipe is the outlet of the mixing pipe; the nozzle is installed in the first opening through a nozzle mounting seat.

9. The cartridge SCR mixer of claim 8, wherein, The inside of the cyclone pipe is provided with cyclone vanes or a wire mesh.

10. An aftertreatment system characterized by, The cylinder SCR mixer comprises a cylinder SCR mixer according to any one of claims 1 to 9, a first open end of the cylinder SCR mixer is connected with a DPF and a DOC in sequence, a second open end of the cylinder SCR mixer is connected with an SCR or an ASC, the DOC is provided with a gas inlet, the SCR or the ASC is provided with a gas outlet, and a longitudinal axis of the cylinder SCR mixer coincides with a longitudinal axis of the aftertreatment system.

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