CN112459875A

CN112459875A - Post-treatment urea mixing device

Info

Publication number: CN112459875A
Application number: CN202011429215.7A
Authority: CN
Inventors: 孟家帅; 牛雨飞; 朱海艳; 徐谦; 李江飞
Original assignee: Quanjiao Yili Environmental Protection Technology Co ltd; Wuxi Yili Environmental Protection Technology Co Ltd; Hebei Yili Technology Co Ltd
Current assignee: Quanjiao Yili Environmental Protection Technology Co ltd; Wuxi Yili Environmental Protection Technology Co Ltd; Hebei Yili Technology Co Ltd
Priority date: 2020-12-09
Filing date: 2020-12-09
Publication date: 2021-03-09
Anticipated expiration: 2040-12-09
Also published as: CN112459875B

Abstract

The invention discloses a post-treatment urea mixing device, wherein a partition plate is transversely arranged between a front shell and a rear shell, a mixing assembly vertically penetrates through the center of the partition plate along the longitudinal direction, the mixing assembly comprises a vertically arranged barrel body, and the barrel body is of an 8-shaped cylindrical structure formed by intersecting double circular tubes. Compared with a straight-barrel-shaped mixing barrel, the barrel body has the advantages that the occupied space between the front shell and the rear shell is larger, the airflow flowing area of the cross section of the barrel body is larger, the space utilization rate is improved, and the back pressure value is reduced; the urea liquid drop can obtain larger pyrolysis and mixing area in the mixing cavity, so that the urea liquid drop can be fully pyrolyzed and mixed, urea crystal formation and urea crystal accumulation are avoided, and NO is ensured_xThe conversion efficiency of the engine ensures that the tail gas normally flows and the normal work of the engine.

Description

Post-treatment urea mixing device

Technical Field

The invention relates to the technical field of automobile exhaust aftertreatment, in particular to a urea aftertreatment mixing device.

Background

With the implementation of the national six-emission regulations, countries are increasingly strict with respect to engine emission limits. Currently, diesel engines usually employ DOC (oxidative catalyst) + DPF (particulate filter) + SCR (selective catalytic reduction) technology to perform after-treatment on exhaust emission, wherein the SCR part mainly converts urea solution ejected by a urea injection system into ammonia (NH) at a certain temperature₃) With NO in the diesel exhaust_x(nitrogen oxide) is mixed and reduced into nitrogen (N) without pollution to the atmosphere under the action of a catalyst₂) And water (H)₂O）。

The existing post-treatment urea mixer generally has the problems of poor gas flow velocity distribution uniformity and low space utilization rate; poor uniformity of gas flow velocity distribution can lead to non-uniform catalyst aging on the one hand; on the other hand, because the gas flow velocity distribution is uneven, the temperature of the inner wall surface of the tail gas aftertreatment mixing device in the area with small gas flow velocity is low, and when urea liquid drops contact with the inner wall surface of the part, a part of heat can be taken away, so that the temperature of the inner wall surface of the part is further reduced, and the urea liquid drops falling on the inner wall surface with too low temperature are easy to form urea crystals due to insufficient heat absorption and volatilization, so that the conversion efficiency of aftertreatment is reduced; and the accumulation of urea crystals can block pipelines, influence the normal flow of tail gas of an engine, increase the back pressure of an exhaust system, even block the surface of a carrier of an SCR mixer, cause aftertreatment failure and influence the normal work of the engine. The low space utilization of the mixer results in a large back pressure value of the mixer and a large loss of engine power.

Disclosure of Invention

The applicant aims at the defects of poor flow velocity distribution uniformity, low space utilization rate, large backpressure value and the like of the existing after-treatment urea mixer, and provides an after-treatment urea mixing device with a reasonable structure, high flow velocity distribution uniformity, high space utilization rate and small backpressure value.

The technical scheme adopted by the invention is as follows:

a post-treatment urea mixing device is characterized in that an internal cavity is formed between a front shell and a rear shell, a partition plate is transversely arranged between the front shell and the rear shell, and the internal cavity is divided into an upper air inlet cavity and a lower air outlet cavity; the upper part of the front shell is provided with an air inlet communicated with the air inlet cavity, and the lower part of the front shell is provided with an air outlet communicated with the air outlet cavity; the center of the clapboard is vertically penetrated and provided with a mixing component along the longitudinal direction, the mixing component comprises a vertically arranged cylinder body, a communicated mixing cavity is arranged in the cylinder body, and the mixing cavity is communicated with an air inlet cavity and an air outlet cavity; the barrel is an 8-shaped cylindrical structure formed by intersecting double round pipes, and two communicated major arc cylindrical cavities are arranged inside the barrel.

Compared with a straight-barrel-shaped mixing barrel, the barrel body has the advantages that the occupied space between the front shell and the rear shell is larger, the airflow flowing area of the cross section of the barrel body is larger, namely the mixing cavity volume and the airflow flowing area which are as large as possible are obtained through the 8-shaped structure in the effective cavity volume between the front shell and the rear shell, the space utilization rate is improved, and the back pressure value is reduced; the urea liquid drop can obtain larger pyrolysis and mixing area in the mixing cavity, so that the urea liquid drop can be fully pyrolyzed and mixed, urea crystal formation and urea crystal accumulation are avoided, and NO is ensured_xThe conversion efficiency of the engine ensures that the tail gas normally flows and the normal work of the engine.

As a further improvement of the above technical solution:

the upper end nozzle of barrel is first horn mouth, and first horn mouth is big-end-up.

The first bell mouth of the cylinder body has a flow guiding function on the tail gas flow entering the mixing cavity, so that the tail gas flow can change the flowing direction stably, the uniformity of the flow velocity of the gas flow is improved, the vortex effect is avoided, the noise of the gas flow is reduced, meanwhile, the flowing area of the gas flow is reduced from large to small, the flow velocity is increased rapidly after the gas flow enters from the first bell mouth, the tail gas flow is mixed with urea liquid drops, the urea liquid drops are fully absorbed by heat and volatilized, and the formation of urea crystals is avoided.

The upper part of the air inlet is provided with a baffle.

The baffle plate can enable the tail gas flow to horizontally enter the inner cavity from the gas inlet and then turn upwards for a certain distance, so that the moving path of the tail gas flow is prolonged while the uniform flow rate of the gas flow at the gas inlet is ensured, the tail gas flow can fully preheat each wall surface, urea liquid drops dropping on each wall surface can fully absorb heat and volatilize, and the formation of urea crystals and further the accumulation of the urea crystals are avoided.

A guide cylinder is fixedly arranged on the inner wall surface of the inclined plane of the rear shell, and the lower end part of the guide cylinder extends into the cylinder body; the cylinder mouth of the lower end part of the guide cylinder is a second horn mouth with a large outside and a small inside.

The guide cylinder provided by the invention surrounds the periphery of the urea nozzle, and can guide all urea liquid drops sprayed by the urea nozzle to be sprayed into a mixing cavity of the mixing component, so that urea crystals are prevented from being formed by the urea liquid drops splashing on the inner wall surfaces of the front shell and the rear shell. The nozzle at the lower end part of the guide cylinder is a second horn nozzle with a large outside and a small inside, urea liquid drops can be guided to be sprayed towards the region with higher airflow velocity and temperature in the cylinder body, the risk of urea crystallization in low-velocity and low-temperature regions is reduced, and meanwhile the urea liquid drops can fully absorb heat and volatilize, so that NO is guaranteed_xThe conversion efficiency of the engine ensures that the tail gas normally flows and the normal work of the engine.

The top end of the rear shell is provided with an inclined plane, and a nozzle seat is arranged on the inclined plane and right opposite to the mixing assembly.

A guide plate, a plurality of first pore plates and a second pore plate are sequentially and radially arranged in the cylinder from top to bottom.

The guide plate is an arc plate.

The middle part of the upper edge of the guide plate is provided with a notch which is positioned under the nozzle seat.

The guide plate further guides the entering tail gas flow, so that the tail gas flow turns to move to the front side for a certain distance, the uniformity of the flow velocity of the tail gas flow is further improved, meanwhile, the movement path of the tail gas flow is further prolonged, the tail gas flow fully preheats all wall surfaces, urea liquid drops fully absorb heat and volatilize, and urea crystals are prevented from being formed and further urea crystal accumulation is avoided. The notch on the edge of the guide plate is positioned under the urea nozzle, and because the flow velocity and the temperature of the air flow at the central part of the guide plate are slightly lower than those of other parts, the notch is arranged at the middle part, so that the distance between the urea nozzle and the edge of the guide plate can be increased, and the risk of forming urea crystals in a low-flow-velocity and low-temperature area is reduced.

The first orifice plate comprises plate surface parts on two sides and a plurality of bridge parts for connecting the two plate surface parts, a plurality of first openings are formed between the two plate surface parts and the bridge parts, a plurality of first through holes are formed in the plate surface parts, and the opening area of each first opening is larger than that of each first through hole; two plate surfaces of the first orifice plate are respectively positioned in two major arc cylindrical cavities of the cylinder body.

The second pore plate is provided with a plurality of second openings and second through holes, and the opening area of the second openings is larger than that of the second through holes; the second opening is located directly below the first orifice plate face portion.

The first pore plate and the second pore plate are provided with the openings with larger opening areas and the through holes with smaller opening areas, so that urea liquid drops sprayed by the urea nozzle are fully crushed, and the flow passing area is as large as possible, thereby being beneficial to reducing the airflow backpressure, ensuring the normal flow of tail gas and ensuring the normal work of an engine.

The invention has the following beneficial effects:

compared with a straight-barrel-shaped mixing barrel, the barrel body has the advantages that the occupied space between the front shell and the rear shell is larger, the airflow flowing area of the cross section of the barrel body is larger, namely the mixing cavity volume and the airflow flowing area which are as large as possible are obtained through the 8-shaped structure in the effective cavity volume between the front shell and the rear shell, the space utilization rate is improved, and the back pressure value is reduced; urea liquid drop in mixing cavityLarger pyrolysis and mixing area can be obtained, so that urea liquid drops can be fully pyrolyzed and mixed, urea crystals are prevented from being formed and accumulated, and NO is ensured_xThe conversion efficiency of the engine ensures that the tail gas normally flows and the normal work of the engine.

Drawings

Fig. 1 is a perspective view of the present invention.

Fig. 2 is an exploded view of fig. 1.

Fig. 3 is a front-rear longitudinal sectional view of fig. 1.

Fig. 4 is a perspective cut-away view of the mixing assembly.

Fig. 5 is a perspective view of a baffle.

Fig. 6 is a perspective view of a first orifice plate.

Fig. 7 is a perspective view of a second orifice plate.

In the figure: 1. a front housing; 11. an air inlet; 12. an air outlet; 2. a rear housing; 21. a slanted plane; 3. a nozzle holder;

4. a mixing assembly; 41. a barrel; 411. a first bell mouth; 42. a baffle; 421. a notch; 43. a first orifice plate; 431. a plate surface portion; 432. a bridge portion; 433. a first through hole; 434. a first opening; 44. a second orifice plate; 441. a second opening; 442. a second through hole;

5. a baffle plate; 6. a partition plate; 7. a draft tube; 71. a second bell mouth;

10. an air inlet cavity; 20. an air outlet cavity; 30. a mixing chamber.

Detailed Description

The following describes embodiments of the present invention with reference to the drawings.

As shown in fig. 1, 2 and 3, the cross section of the whole body along the longitudinal axis is in the shape of a peanut shell, the front shell 1 of the peanut shell is fixed on the rear shell 2, and an internal cavity is formed between the front shell 1 and the rear shell 2; the upper part of the front shell 1 is provided with a cylindrical air inlet 11, and the lower part is provided with a cylindrical air outlet 12; the upper portion of air inlet 11 is provided with semicircular baffle 5, baffle 5 can make the tail gas air current follow air inlet 11 level get into inside cavity after, turn to a certain distance of upward movement again, when guaranteeing that the air current velocity of flow of air inlet 11 is even, the motion route of tail gas air current has been prolonged for the tail gas air current carries out abundant preheating to each wall, makes the urea liquid drop of drippage on each wall fully absorb heat and volatilize, has avoided forming the urea crystallization, and then has avoided the urea crystallization to pile up. As shown in fig. 3 and 4, a partition plate 6 is horizontally and transversely arranged at the middle position of the front shell 1 and the rear shell 2, the partition plate 6 is fixed on the wall surfaces of the front shell 1 and the rear shell 2 by welding, the partition plate 6 divides an internal cavity between the front shell 1 and the rear shell 2 into an upper air inlet cavity 10 and a lower air outlet cavity 20, the air inlet cavity 10 is communicated with an air inlet 11, and the air outlet cavity 20 is communicated with an air outlet 12; the center of the baffle plate 6 is vertically penetrated and provided with the mixing component 4 along the longitudinal direction, a communicated mixing cavity 30 is arranged inside the mixing component 4, and the mixing cavity 30 is communicated with the air inlet cavity 10 and the air outlet cavity 20. The top end of the rear shell 2 is provided with an inclined plane 21, a nozzle holder 3 is arranged on the inclined plane 21 and opposite to the mixing component 4, and a urea nozzle (not shown in the figure) is arranged in the nozzle holder 3 and can spray urea liquid drops into the mixing component 4.

As shown in fig. 3 and 4, the mixing assembly 4 includes a vertically arranged cylinder 41, the cylinder 41 is an "8" cylindrical structure formed by intersecting double circular tubes, the mixing chamber 30 is arranged inside the cylinder 41, and the cylinder has two communicated major arc cylindrical cavities, and compared with a straight cylindrical mixing cylinder, the cylinder 41 occupies a larger space between the front housing 1 and the rear housing 2, and has a larger cross-sectional airflow area, that is, in an effective cavity volume between the front housing 1 and the rear housing 2, the volume of the mixing chamber 30 and the airflow area are obtained as large as possible by the "8" shaped structure, so that the space utilization rate is improved, and the back pressure value is reduced; urea dropletsLarger pyrolysis and mixing area can be obtained in the mixing cavity 30, so that urea liquid drops can be fully pyrolyzed and mixed, urea crystals are prevented from being formed and accumulated, and NO is ensured_xThe conversion efficiency of the engine ensures that the tail gas normally flows and the normal work of the engine. The upper end nozzle of barrel 41 is first horn mouth 411, first horn mouth 411 is big-end-up, there is a water conservancy diversion effect to the tail gas air current that gets into mixing chamber 30, make the tail gas air current change flow direction steadily, be favorable to improving the homogeneity of the air current velocity, avoid producing the vortex effect, reduce the production of air current noise, the air current flow area simultaneously by big to little reduction, the air current gets into the back from first horn mouth 411, the velocity of flow increases rapidly, more do benefit to the mixture of tail gas air current and urea liquid drop, make the abundant heat absorption of urea liquid drop volatilize, avoid forming the urea crystallization.

As shown in fig. 3 and 4, a guide plate 42, a plurality of first orifice plates 43, and a second orifice plate 44 are sequentially and radially arranged in the cylinder 41 from top to bottom. As shown in fig. 4 and 5, the guide plate 42 is an arc plate, and further guides the entering exhaust gas flow to turn to move a distance to the front side, so that the uniformity of the flow velocity of the exhaust gas flow is further improved, and meanwhile, the movement path of the exhaust gas flow is further extended, so that the exhaust gas flow fully preheats each wall surface, urea droplets are fully volatilized by heat absorption, and urea crystals are prevented from being formed and further urea crystals are prevented from being accumulated; the notch 421 of V-arrangement is seted up at the last border middle part of guide plate 42, and the notch 421 is located nozzle block 3 under, because the air current velocity of flow and the temperature of guide plate 42 central part will be slightly lower than other positions, sets up notch 421 in the middle part, can increase the distance between urea nozzle and the guide plate 42 border, reduces the risk that forms the urea crystallization at this low velocity of flow, low temperature region. The first orifice plate 43 includes plate portions 431 on both sides and bridge portions 432 connecting the plate portions 431, a plurality of first openings 434 are formed between the plate portions 431 and the bridge portions 432, a plurality of first through holes 433 are formed in the plate portions 431, and the first openings 434 have a larger opening area relative to the first through holes 433; as shown in fig. 4, the two plate surfaces 431 of the first orifice plate 43 are respectively located in the two major arc cylindrical cavities with higher airflow velocity and temperature in the cylinder 41, and the plurality of first openings 434 are located in the middle of the cylinder 41 with relatively lower airflow velocity and temperature. Second openings 441 with large opening areas are respectively formed in the second orifice plate 44 and located right below the plate surface portion 431 of the first orifice plate 43, and a plurality of second through holes 442 with small opening areas are further formed in the second orifice plate 44 and located on the outer side of the second openings 441. The first orifice plate 43 and the second orifice plate 44 are provided with openings (the first opening 434 and the second opening 441) with large opening areas and a plurality of through holes (the first through hole 433 and the second through hole 442) with small opening areas, so that urea liquid drops sprayed by the urea nozzle are fully crushed, and meanwhile, the flow area is as large as possible, which is beneficial to reducing the back pressure of air flow, ensuring the normal flow of tail gas and ensuring the normal work of an engine.

As shown in fig. 2 and 3, the inner wall surface of the inclined plane 21 of the rear housing 2 is fixedly provided with a guide cylinder 7, the lower end of the guide cylinder 7 extends into the first bell mouth 411 of the cylinder 41, the guide cylinder 7 surrounds the periphery of the urea nozzle, and can guide all urea droplets sprayed by the urea nozzle to be sprayed into the mixing cavity 30 of the mixing component 4, so as to prevent the urea droplets from splashing on the inner wall surfaces of the front housing 1 and the rear housing 2 to form urea crystals; the nozzle at the lower end part of the guide cylinder 7 is a second horn-shaped nozzle 71 with a large outside and a small inside, urea liquid drops can be guided to be sprayed towards the area with higher airflow velocity and temperature in the cylinder 41, the risk of urea crystallization in low-velocity and low-temperature areas is reduced, and meanwhile the urea liquid drops can fully absorb heat and volatilize, so that NO is guaranteed_xThe conversion efficiency of the engine ensures that the tail gas normally flows and the normal work of the engine.

When the urea spraying device is actually used, urea liquid drops are sprayed into the mixing component 4 from the urea nozzle in the nozzle seat 3, tail gas flows into the air inlet cavity 10 from the air inlet 11, the tail gas flows into the mixing cavity 30 through the first bell mouth 411 of the cylinder 41 of the mixing component 4 in an accelerated mode to be mixed with the urea liquid drops, the mixed tail gas flows sequentially pass through the first pore plates 43 and the second pore plates 44, are fully crushed and mixed through the multiple layers of pore plates, then flow into the air outlet cavity 20, and are discharged from the air outlet 12.

The cylinder body 41 of the mixing component 4 adopts an 8 shape, so that the space utilization rate is improved, and the reduction of the number of partsThe backpressure value is high, urea liquid drops can be fully pyrolyzed and mixed in the mixing cavity 30, urea crystals are prevented from being formed and accumulated, and NO is guaranteed_xThe conversion efficiency of the engine ensures that the tail gas normally flows and the normal work of the engine.

The foregoing description is illustrative of the present invention and is not to be construed as limiting thereof, as the invention may be modified in any manner without departing from the spirit thereof.

Claims

1. A post-treatment urea mixing device is characterized in that an internal cavity is formed between a front shell (1) and a rear shell (2), a partition plate (6) is transversely arranged between the front shell (1) and the rear shell (2) to divide the internal cavity into an upper air inlet cavity (10) and a lower air outlet cavity (20); the upper part of the front shell (1) is provided with an air inlet (11) communicated with the air inlet cavity (10), and the lower part of the front shell is provided with an air outlet (12) communicated with the air outlet cavity (20); the method is characterized in that: the center of the partition plate (6) is vertically penetrated and provided with a mixing component (4) along the longitudinal direction, the mixing component (4) comprises a vertically arranged cylinder body (41), a communicated mixing cavity (30) is arranged in the cylinder body (41), and the mixing cavity (30) is communicated with the air inlet cavity (10) and the air outlet cavity (20); the cylinder body (41) is in an 8-shaped cylindrical structure formed by intersecting double round pipes, and two communicated major arc cylindrical cavities are arranged inside the cylinder body.

2. The aftertreatment urea mixing device of claim 1, wherein: the upper end opening of the cylinder body (41) is a first bell mouth (411), and the first bell mouth (411) is large in outside and small in inside.

3. The aftertreatment urea mixing device of claim 1, wherein: the upper part of the air inlet (11) is provided with a baffle (5).

4. The aftertreatment urea mixing device of claim 1, wherein: a guide cylinder (7) is fixedly arranged on the inner wall surface of the inclined plane (21) of the rear shell (2), and the lower end part of the guide cylinder (7) extends into the cylinder body (41); the cylinder mouth of the lower end part of the guide cylinder (7) is a second bell mouth (71) with a large outside and a small inside.

5. The aftertreatment urea mixing device of claim 1, wherein: the top end of the rear shell (2) is provided with an inclined plane (21), and a nozzle seat (3) is arranged on the inclined plane (21) and is opposite to the mixing component (4).

6. The aftertreatment urea mixing device of claim 1, wherein: a guide plate (42), a plurality of first pore plates (43) and a second pore plate (44) are sequentially and radially arranged in the cylinder body (41) from top to bottom.

7. The aftertreatment urea mixing device of claim 6, wherein: the guide plate (42) is a circular arc plate.

8. The aftertreatment urea mixing device of claim 6, wherein: a notch (421) is formed in the middle of the upper edge of the guide plate (42), and the notch (421) is located right below the nozzle seat (3).

9. The aftertreatment urea mixing device of claim 6, wherein: the first orifice plate (43) comprises plate surface parts (431) on two sides and a plurality of bridge parts (432) connecting the two plate surface parts (431), a plurality of first openings (434) are formed between the two plate surface parts (431) and the bridge parts (432), a plurality of first through holes (433) are formed in the plate surface parts (431), and the opening area of the first openings (434) is larger than that of the first through holes (433); two plate surface parts (431) of the first orifice plate (43) are respectively positioned in two major arc cylindrical cavities of the cylinder body (41).

10. The aftertreatment urea mixing device of claim 6, wherein: the second pore plate (44) is provided with a plurality of second openings (441) and second through holes (442), and the opening area of the second openings (441) is larger than that of the second through holes (442); the second opening (441) is positioned directly below the panel surface portion (431) of the first aperture plate (43).