CN111005789B - Urea SCR mixer, tail gas aftertreatment system and diesel vehicle - Google Patents
Urea SCR mixer, tail gas aftertreatment system and diesel vehicle Download PDFInfo
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- CN111005789B CN111005789B CN201911380504.XA CN201911380504A CN111005789B CN 111005789 B CN111005789 B CN 111005789B CN 201911380504 A CN201911380504 A CN 201911380504A CN 111005789 B CN111005789 B CN 111005789B
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- support frame
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- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 title claims abstract description 88
- 239000004202 carbamide Substances 0.000 title claims abstract description 88
- 238000009792 diffusion process Methods 0.000 claims abstract description 6
- 238000009423 ventilation Methods 0.000 claims description 77
- 238000005192 partition Methods 0.000 claims description 21
- 238000005273 aeration Methods 0.000 claims description 3
- 239000007788 liquid Substances 0.000 abstract description 13
- 238000006243 chemical reaction Methods 0.000 abstract description 7
- 238000002425 crystallisation Methods 0.000 abstract description 7
- 230000008025 crystallization Effects 0.000 abstract description 7
- 230000003197 catalytic effect Effects 0.000 abstract description 5
- 230000008021 deposition Effects 0.000 abstract description 3
- 239000007789 gas Substances 0.000 description 27
- 230000000694 effects Effects 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 4
- 238000013022 venting Methods 0.000 description 4
- 238000005452 bending Methods 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 230000007062 hydrolysis Effects 0.000 description 3
- 238000006460 hydrolysis reaction Methods 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000000197 pyrolysis Methods 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2066—Selective catalytic reduction [SCR]
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2066—Selective catalytic reduction [SCR]
- F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Exhaust Gas After Treatment (AREA)
Abstract
The invention belongs to the technical field of diesel vehicles, and discloses a urea SCR mixer, a tail gas aftertreatment system and a diesel vehicle. The urea SCR mixer comprises a primary mixer and a secondary mixer, and comprises a support frame and a plurality of first guide vanes obliquely arranged on different parts of the support frame, wherein each first guide vane is inclined towards the central direction of the support frame and is configured to enable urea liquid drops and NH 3 Diversion to the central region of the primary mixer; the secondary mixer is positioned downstream of the primary mixer and is connected to the primary mixer by a connecting shaft, the secondary mixer including a plurality of swirl vanes connected to the connecting shaft, the swirl vanes being configured to enable urea droplets and NH 3 And the diffusion is realized by swirling from inside to outside. So that NH before entering SCR end face 3 The distribution in the tail gas exhaust pipe is more uniform, the efficiency and the utilization rate of SCR catalytic conversion are increased, and the risk of urea deposition is reduced, so that the risk of urea crystallization is reduced.
Description
Technical Field
The invention relates to the technical field of diesel vehicles, in particular to a urea SCR mixer, a tail gas aftertreatment system and a diesel vehicle.
Background
At present, with the increasing emphasis of the national environmental protection problem, the higher requirements are put on the exhaust emission of the diesel engine, wherein nitrogen oxides NO X The emission limit was reduced to 3.5 g/(kw.h). In a plurality of NO X Among the treatment technologies, the Selective Catalytic Reduction (SCR) technology is currently considered the most promising, most widely used technology, and is well established. The mechanism is as follows: the high-temperature exhaust pipe is provided with a urea metering and spraying device for spraying urea aqueous solution into the high-temperature exhaust pipe, and urea is hydrolyzed and pyrolyzed at high temperatureAfter the reaction, NH is generated 3 ，NH 3 Has reducibility and can make NO react with specific catalyst X Reduction to pollution-free N 2 And H 2 O, thereby reducing the emission of pollutants.
With the increasing maturity of SCR technology and the limitation of the installation space of the whole vehicle aftertreatment system, the structure of the SCR system is more and more compact. The imperfect structural design will cause the problems of insufficient evaporation efficiency and uneven distribution of urea, and the crystallization is easy to form on the inner wall of SCR or the front end surface of the carrier, and the engine performance is seriously affected even, so that the problems of uniformity in urea distribution, evaporation efficiency, crystallization and the like must be emphasized in the structural design of SCR.
While urea hydrolyzes to NH 3 Can only be combined with NO X The hydrolysis of urea is mainly realized by a mixer at present, but the mixer adopted at present is easy to generate larger back pressure, affects the power of an engine, can not effectively reduce the concentration of urea due to insufficient hydrolysis of urea, and is easy to generate crystallization.
In the current mixers, almost all single-stage mixers can only make NH under certain specific working conditions 3 The uniformity of (2) meets the requirements, under some limit working conditions, such as low-load working conditions, the flow is lower, urea is easy to spray at the bottom of the mixer, and under high-load working conditions, the tail gas speed is high, urea is impacted by high-speed tail gas, and urea liquid drops are concentrated at the upper part of the mixer. Thus, NH at lower or higher load conditions 3 The concentration is higher in a certain part of a cross section, which results in NH when entering the SCR 3 Uneven distribution, leading to NO X The conversion is uneven and the efficiency is low.
Disclosure of Invention
It is an object of the present invention to provide a urea SCR mixer that increases NH 3 The distribution uniformity of the catalyst improves the efficiency and the utilization rate of SCR catalytic conversion.
The invention further aims to provide a tail gas aftertreatment system, which is high in tail gas treatment efficiency, environment-friendly and energy-saving.
The invention also aims to provide a diesel vehicle, which has high tail gas treatment efficiency, is environment-friendly and saves energy.
To achieve the purpose, the invention adopts the following technical scheme:
a urea SCR mixer, comprising:
the primary mixer comprises a support frame and a plurality of first guide vanes obliquely arranged on different parts of the support frame, wherein each first guide vane inclines towards the central direction of the support frame and is configured to enable urea liquid drops and NH 3 Diversion to the central region of the primary mixer;
a secondary mixer downstream of and connected to the primary mixer by a connecting shaft, the secondary mixer comprising a plurality of swirl vanes connected to the connecting shaft, the swirl vanes being configured to enable the urea droplets and NH to be mixed 3 And the diffusion is realized by swirling from inside to outside.
As a preferable technical scheme of the urea SCR mixer, the support frame comprises a first ventilation area and a plurality of second ventilation areas, wherein the first ventilation area and the plurality of second ventilation areas are formed by surrounding a partition plate, and the plurality of second ventilation areas are distributed at intervals along the circumferential direction of the first ventilation area; the first guide vanes are arranged on the partition plate at the outermost periphery of the first ventilation area and the partition plate at the outermost periphery of the second ventilation area.
As a preferred technical solution of the urea SCR mixer, the first ventilation zone and the second ventilation zone are each divided into a plurality of sub-ventilation zones by sub-partitions.
As a preferable technical scheme of the urea SCR mixer, the plurality of sub aeration areas have the same size.
As the preferable technical scheme of the urea SCR mixer, the cross section of the first ventilation area is square, the cross section of the second ventilation area is rectangular and is provided with four, the four second ventilation areas are respectively arranged on the periphery of the first ventilation area, the sides of the square are overlapped with the long sides of the rectangle, and the short sides of the rectangle are equal to one half of the long sides.
As the preferable technical scheme of the urea SCR mixer, an extension baffle is arranged between every two adjacent second ventilation areas, second guide vanes are obliquely arranged on the extension baffle, and the second guide vanes are obliquely oriented towards the central direction of the supporting frame.
As a preferable technical scheme of the urea SCR mixer, the swirl vanes are fan-shaped.
As the preferable technical scheme of the urea SCR mixer, a plurality of swirl vanes are uniformly distributed on the connecting shaft along the circumferential direction.
The tail gas aftertreatment system comprises a tail gas exhaust pipe and the urea SCR mixer, wherein the urea SCR mixer is fixedly arranged in the tail gas exhaust pipe.
A diesel vehicle comprises the tail gas aftertreatment system.
Compared with the prior art, the invention has the advantages that:
the invention provides a urea SCR mixer, which comprises a primary mixer and a secondary mixer, wherein the primary mixer comprises a support frame and a plurality of first guide vanes obliquely arranged on different parts of the support frame, each first guide vane is inclined towards the center direction of the support frame and is configured to enable urea liquid drops and NH to be discharged 3 Diversion to the central region of the primary mixer; then passing through a cyclone vane type secondary mixer to make the urea liquid drop and NH in the middle 3 Uniformly spread outwards to enable NH before entering SCR end face 3 The distribution in the tail gas exhaust pipe is more uniform, the efficiency and the utilization rate of SCR catalytic conversion are increased, the urea drop quantity at the front end face of the SCR is reduced, and the risk of urea deposition is reduced, so that the risk of urea crystallization is reduced; and the urea SCR mixer has compact and simple structure and lower cost.
The tail gas aftertreatment system provided by the invention comprises a tail gas exhaust pipe and the urea SCR mixer, wherein the urea SCR mixer is fixedly arranged in the tail gas exhaust pipe. The tail gas aftertreatment system has high tail gas treatment efficiency, and is environment-friendly and energy-saving.
The diesel vehicle provided by the invention comprises the tail gas aftertreatment system, and is high in tail gas treatment efficiency, environment-friendly and energy-saving.
Drawings
FIG. 1 is a schematic diagram of a urea SCR mixer provided in an embodiment of the present invention;
FIG. 2 is an exploded schematic view of a urea SCR mixer provided in an embodiment of the present invention;
fig. 3 is an end face front view of an exhaust pipe according to an embodiment of the present invention.
The figures are labeled as follows:
1. a primary mixer; 11. a support frame; 111. a first venting region; 112. a second venting region; 113. an extension spacer; 12. a first guide vane; 13. a second guide vane;
2. a secondary mixer; 21. swirl vanes;
3. a connecting shaft;
100. an exhaust pipe.
Detailed Description
In order to make the technical problems solved, the technical scheme adopted and the technical effects achieved by the invention more clear, the technical scheme of the invention is further described below by a specific embodiment in combination with the attached drawings.
In the description of the present invention, unless explicitly stated and limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.
In the description of the present embodiment, the terms "upper", "lower", "left", "right", and the like are orientation or positional relationships based on those shown in the drawings, and are merely for convenience of description and simplicity of operation, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the invention. Furthermore, the terms "first," "second," and the like, are used merely for distinguishing between descriptions and not for distinguishing between them.
The embodiment discloses a urea SCR mixer, as shown in fig. 1 and 2, which comprises two single-stage mixers, namely a first-stage mixer 1 and a second-stage mixer 2, wherein the second-stage mixer 2 is close to the front end face of SCR. The two mixers are structurally different and function differently. Wherein, as shown in FIG. 2, the primary mixer 1 comprises a support frame 11 and a plurality of first guide vanes 12 obliquely arranged on different parts of the support frame 11, each first guide vane 12 is inclined towards the center direction of the support frame 11, and the first guide vanes 12 are configured to enable urea drops and NH 3 Diversion to the central region of the primary mixer 1; the secondary mixer 2 is located downstream of the primary mixer 1 and is connected to the primary mixer 1 by a connecting shaft 3, the secondary mixer 2 comprising a plurality of swirl vanes 21 connected to the connecting shaft 3, the swirl vanes 21 being configured to enable urea droplets and NH to be mixed 3 And the diffusion is realized by swirling from inside to outside.
The urea SCR mixer in the embodiment adopts two single-stage mixers with different functions, and combines the two mixers together to make up the respective defects of the two mixers: the primary mixer 1 divides urea droplets and NH into regions by means of the first guide vanes 12 3 Guided to the middle area and increasedAdding turbulence intensity, passing through a cyclone vane type secondary mixer 2 to make the urea liquid drop and NH in the middle 3 Uniformly spread outwards to enable NH before entering SCR end face 3 More evenly distributed in the exhaust pipe 100, increasing the efficiency and utilization of the SCR catalytic conversion. By arranging the two-stage mixer, the primary crushing degree of urea liquid drops is increased, the secondary crushing is increased, the pyrolysis amount of the urea liquid drops when passing through the mixer is further increased, the urea liquid drop amount at the front end face of the SCR is reduced, and the risk of urea deposition is reduced, so that the risk of urea crystallization is reduced; and the urea SCR mixer has compact and simple structure and lower cost.
Specifically, as shown in fig. 3, the support frame 11 includes a first ventilation area 111 and a plurality of second ventilation areas 112 surrounded by a partition, and the plurality of second ventilation areas 112 are distributed at intervals along the circumferential direction of the first ventilation area 111; the first guide vane 12 is provided on the outermost partition of the first ventilation area 111 and on the outermost partition of the second ventilation area 112. As shown in fig. 1-3, the first ventilation area 111 is located in the central area of the support frame 11, and the plurality of second ventilation areas 112 are respectively arranged on the periphery of the first ventilation area 111, in this structure, the support frame 11 divides the exhaust pipe 100 into a plurality of areas, and each area is provided with a first guide vane 12, the first guide vanes 12 are obliquely arranged towards the central area direction, and can be used for mixing urea droplets and NH 3 Leading to the middle area. And the baffle plate structure and the first guide vane 12 work together to increase turbulence intensity, thereby facilitating the breaking and hydrolysis of urea liquid drops.
Further, the first and second venting areas 111, 112 are each divided into a plurality of sub-venting areas by sub-baffles to further increase turbulence intensity. Preferably, the multiple sub-aeration zones are the same size, such that urea droplets and NH 3 The distribution in the exhaust pipe 100 is more uniform, improving the efficiency and the utilization rate of the SCR catalytic conversion. It is further preferred that the first guide vanes 12 are provided at the edges of the respective sub-ventilation areas, respectively.
In this embodiment, as shown in fig. 3, the cross section of the first ventilation area 111 is square, the cross section of the second ventilation area 112 is rectangular and four second ventilation areas 112 are respectively disposed around the first ventilation area 111, the sides of the square overlap with the long sides of the rectangle, and the short sides of the rectangle are equal to one half of the long sides. In this configuration, each sub-ventilation area is square and of equal size, and the peripheral edge of each sub-ventilation area is provided with a first guide vane 12. It will be appreciated that the support frame 11 provided in this embodiment may be considered as a frame structure formed by a sixteen grid frame with the grid removed at the four corners.
Specifically, the first ventilation area 111 may be taken as a middle area, and the four second ventilation areas 112 are respectively an upper ventilation area, a lower ventilation area, a left ventilation area, and a right ventilation area, so that the support frame 11 composed of the partition plates divides the ventilation space of the exhaust pipe 100 into five areas, and the upper ventilation area and the lower ventilation area are disposed vertically symmetrically with respect to the middle area, and the left ventilation area and the right ventilation area are disposed horizontally symmetrically with respect to the middle area. The first guide vane 12 of the upper ventilation area is bent downwards, under the high load working condition, as the airflow speed is very high, the momentum exchange between the air and urea drops is large, the urea which is not pyrolyzed in time is blown to the upper half part of the primary mixer 1, and the urea drops which are dropped on the upper half part are pyrolyzed, under the guide effect of the first guide vane 12 of the area to the middle area, NH can be avoided 3 Concentrated in the upper half area. The first guide vane 12 of the lower ventilation zone bends upwards, urea droplets are more concentrated at the lower half part of the primary mixer 1 under the low-load working condition, and NH can be avoided under the guide effect of the first guide vane 12 of the zone to the middle zone after the urea droplets dropped on the lower half part are pyrolyzed 3 Concentrated in the lower half area. The first guide vane 12 in the left ventilation area is bent to the right, and the first guide vane 12 in the right ventilation area is bent to the left, so that urea droplets near the pipe wall of the exhaust pipe 100 can be guided to the middle area. In the present embodiment, the up, down, left, and right directions are all directions in fig. 3.
Further preferably, an extending partition plate 113 is disposed between two adjacent second ventilation areas 112, and second guide vanes 13 are obliquely disposed on the extending partition plate 113, and the second guide vanes 13 are inclined toward the center direction of the supporting frame 11. Specifically, the extension partition plate 113 located between the upper ventilation area and the left ventilation area, and the extension partition plate 113 located between the upper ventilation area and the right ventilation area are horizontally connected to the partition plate of the upper ventilation area, and the second guide vanes 13 on both the extension partition plates 113 are bent downward; an extension diaphragm 113 located between the lower ventilation area and the left ventilation area, and an extension diaphragm 113 located between the lower ventilation area and the right ventilation area are horizontally connected to the diaphragm of the lower ventilation area, and the second guide vanes 13 on both extension diaphragms 113 are bent upward. Alternatively, the length of the extension partition 113 is designed so as not to affect the installation of the support frame 11 into the exhaust gas pipe 100, and the size of the second guide vane 13 on the extension partition 113 is different from the size of the first guide vane 12 in the first ventilation area 111 and the second ventilation area 112. Illustratively, the width of the second guide vane 13 on the extension diaphragm 113 is smaller than the width of the first guide vane 12, and the length of the second guide vane 13 on the extension diaphragm 113 is greater than the length of the first guide vane 12. For the size design of each guide vane, the present embodiment does not have to be limited too much, so that the guide effect can be better realized.
With the above-described configuration, the primary mixer 1 in this embodiment includes sixteen guide vanes, and the bending angles of the guide vanes in each ventilation area may be the same or different, and may be designed according to the actual situation. Preferably, the bending angles of the first guide vanes 12 disposed in the same ventilation area are kept identical, and the bending angles of the second guide vanes 13 on the extension partition 113 are kept identical to those of the first guide vanes 12 of the ventilation area on the same side. The turbulent flow in different directions and different sizes can be greatly increased by the airflow passing through the primary mixer 1, the turbulent flow intensity is increased, the breaking and decomposition of urea liquid drops are facilitated, and therefore the pyrolysis of urea is promoted, and urea is pyrolyzed into NH as much as possible before entering SCR 3 And H 2 O。
In the present embodiment, the swirl blades 21 of the secondary mixer 2 form a certain angle with the plane, and the plane shape of the swirl blades 21 is fan-shaped like a fan blade, so that the swirl diffusion effect can be better realized.
Further, the swirl vanes 21 are uniformly arranged on the connecting shaft 3 along the circumferential direction, so that urea droplets and NH can be further improved 3 Uniformity of diffusion. Optionally, in this embodiment, eight swirl blades 21 are provided, the eight swirl blades 21 are uniformly welded on the connecting shaft 3, and one end of the connecting shaft 3, where the swirl blades 21 are not provided, is welded on the support frame 11 of the primary mixer 1, so as to form a two-stage SCR mixer with an integral structure. The structure of the connecting shaft 3 may be cylindrical or prismatic, and the present embodiment is not particularly limited.
Due to the effect of the primary mixer 1, urea liquid drops and NH are mixed under different load working conditions of the diesel vehicle 3 Mainly concentrate in the middle area of the exhaust pipe 100, urea drops and NH 3 After impinging on the downstream secondary mixer 2 from the middle zone, the secondary mixer 2 starts to swirl and spread from the middle to the outside, and has better swirling effect like a fan, so that urea liquid drops and NH are concentrated 3 The urea droplets become more uniform before entering the SCR and during the swirling process the urea droplets are further pyrolyzed, further reducing the urea droplets before entering the SCR and thus reducing the risk of urea crystallization. Experiments prove that after the urea SCR mixer provided by the embodiment is adopted, NH of the front end face of the SCR can be met 3 The working condition range required by the uniformity index is greatly increased.
The embodiment also provides a tail gas aftertreatment system, which comprises a tail gas exhaust pipe 100 and the urea SCR mixer, wherein the urea SCR mixer is fixedly arranged in the tail gas exhaust pipe 100. The tail gas aftertreatment system has high tail gas treatment efficiency, and is environment-friendly and energy-saving.
The invention also provides a diesel vehicle, which comprises the tail gas aftertreatment system, and the tail gas treatment efficiency of the diesel vehicle is high, and the diesel vehicle is environment-friendly and energy-saving.
It is to be understood that the above examples of the present invention are provided for clarity of illustration only and are not limiting of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.
Claims (7)
1. A urea SCR mixer, comprising:
the primary mixer (1) comprises a support frame (11) and a plurality of first guide vanes (12) obliquely arranged on different parts of the support frame (11), wherein each first guide vane (12) is inclined towards the central direction of the support frame (11), and the first guide vanes (12) are configured to enable urea drops and NH 3 Flow-guiding to the central region of the primary mixer (1);
a secondary mixer (2) downstream of the primary mixer (1) and connected to the primary mixer (1) by a connecting shaft (3), the secondary mixer (2) comprising a plurality of swirl blades (21) connected to the connecting shaft (3), the swirl blades (21) being configured to enable the urea droplets and NH 3 Swirl diffusion from inside to outside;
the support frame (11) comprises a first ventilation area (111) and a plurality of second ventilation areas (112) which are formed by surrounding a partition plate, and the second ventilation areas (112) are distributed at intervals along the circumferential direction of the first ventilation area (111); the first guide vane (12) is arranged on the partition plate at the outermost periphery of the first ventilation area (111) and the partition plate at the outermost periphery of the second ventilation area (112);
an extension baffle plate (113) is arranged between two adjacent second ventilation areas (112), second guide vanes (13) are obliquely arranged on the extension baffle plate (113), and the second guide vanes (13) are inclined towards the center direction of the supporting frame (11);
the swirl blades (21) are uniformly distributed on the connecting shaft (3) along the circumferential direction.
2. Urea SCR mixer according to claim 1, characterized in that the first ventilation zone (111) and the second ventilation zone (112) are each divided into a plurality of sub-ventilation zones by sub-partitions.
3. The urea SCR mixer of claim 2, wherein a plurality of the sub-aeration zones are the same size.
4. A urea SCR mixer according to claim 3, characterized in that the first ventilation zone (111) has a square cross section, the second ventilation zone (112) has a rectangular cross section and four second ventilation zones (112) are respectively arranged around the first ventilation zone (111), the sides of the square and the long sides of the rectangle coincide, and the short sides of the rectangle are equal to one half of the long sides.
5. Urea SCR mixer according to claim 1, characterized in that the swirl vanes (21) are sector-shaped.
6. An exhaust aftertreatment system, characterized by comprising an exhaust pipe (100) and a urea SCR mixer according to any one of claims 1-5, which is fixedly arranged in the exhaust pipe (100).
7. A diesel vehicle comprising the exhaust aftertreatment system of claim 6.
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| CN201911380504.XA CN111005789B (en) | 2019-12-27 | 2019-12-27 | Urea SCR mixer, tail gas aftertreatment system and diesel vehicle |
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| CN111927602B (en) * | 2020-08-18 | 2022-04-12 | 无锡威孚力达催化净化器有限责任公司 | Mixing device with double cyclone tube cross devices |
| CN112523843B (en) * | 2020-11-17 | 2022-03-22 | 江苏大学 | Control device and method for actively regulating and controlling working environment of diesel engine SDPF system |
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| CN211422736U (en) * | 2019-12-27 | 2020-09-04 | 清华大学苏州汽车研究院（吴江） | Urea SCR mixer, tail gas aftertreatment system and diesel vehicle |
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