CN207018067U - The reactant exhaust mixing arrangement of engine exhaust SCR system - Google Patents
The reactant exhaust mixing arrangement of engine exhaust SCR system Download PDFInfo
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- CN207018067U CN207018067U CN201720389721.5U CN201720389721U CN207018067U CN 207018067 U CN207018067 U CN 207018067U CN 201720389721 U CN201720389721 U CN 201720389721U CN 207018067 U CN207018067 U CN 207018067U
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- reactant
- exhaust
- blender
- reflecting plate
- mixing tube
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Abstract
A kind of reactant exhaust mixing arrangement of SCR system, including a reactant nozzle, an exhaust mixing tube, a reflecting plate, a blender, it is characterised in that：The exhaust mixing tube is straight tube, the blender and reflecting plate are in exhaust mixing tube, blender is co-axially mounted fixation with blast pipe, reflecting plate be located at blender upstream and with the almost parallel fixation of blast pipe axis, on the exhaust mixing tube, nozzle mounting surface is provided with positioned at the position of blender upstream, the nozzle mounting surface and exhaust mixing tube axis bevel, the reactant nozzle is arranged on the nozzle mounting surface, the reactant jet direction ejected and the flow direction of exhaust gases bevel in exhaust mixing tube, the jet of taper diverging sprays to the blender and reflecting plate.
Description
Technical field
The invention belongs to engine exhaust post-processing technology field, and in particular to engine exhaust selective reduction (SCR)
The reducing agent of technology and the mixing arrangement of engine exhaust.
Background technology
With becoming increasingly conspicuous for environmental problem, energy-saving and emission-reduction have become the endless requirement of vehicle and engine,
Therefore, each state has all put into effect a series of vehicular emission standards, and it is more and more stricter.On the other hand, using internal combustion engine as the car of power
Need that discharge post-treatment system is installed in the hope of meeting emission request.For example, it is currently used primarily in in diesel motor exhaust
The pollutants such as NOx carry out SCR (Selective Catalytic Reduction) technology of catalytic treatment etc. and have become diesel oil
The technology that vehicle etc. must use.
SCR technology needs to enter reducing agent metered injection in diesel exhaust gas, enters SCR catalytic conversions after being mixed with exhaust
Device.The aqueous solution of urea that reducing agent has 32.5% weight concentration (is also diesel exhaust gas treatment fluid DEF=Diesel Exhaust
Fluid, either add blue liquid AdBlue) or ammonia.The ammonia that DEF is decomposited in exhaust by exhaust high temperature, or directly
The gaseous state ammonia ejected, SCR catalyst is entered after being mixed with engine exhaust, in the presence of catalyst, ammonia will
Catalytic reduction reaction occurs with the NOx in engine exhaust etc., NOx is decomposed into harmless N2, H2O.If reduction reaction agent
Can not uniformly it be mixed with exhaust, then ammonia will be very uneven with NOx ratio value (ammonia nitrogen ratio) in SCR catalyst, as a result portion
Divide catalyser unit to might have unnecessary ammonia to be leaked in tail gas, and partially catalyzed device unit is difficult in default of ammonia
NOx is set effectively to be degraded.
On the other hand, after the DEF of liquid is ejected into the exhaust pipe of engine, if can not fast pyrogenation be ammonia and with row
Gas is well mixed, then may be because other physicochemical changes and become solid-state junction crystal and remain in blast pipe, for a long time product
It is tired to block the exhaust pipe of engine, make engine performance severe exacerbation.
Crystallizations of the DEF in blast pipe, influenced by many factors, most importantly temperature and two phase flow speed.
Temperature determines chemical reaction product, and flowing velocity determines whether the solid-state junction crystal in product can be accumulated in inside pipeline.
Existing SCR technology, the reactant of ejection will be made to be well mixed with engine exhaust by every means, be adopted for this
SCR system is helped with compressed air atomized spray DEF gas, also reliable pressure injection atomization DEF non-gas helps SCR system,
There is the solid-state ammonia SCR system of directly injection ammonia.But due to the limitation of physical dimension, accomplish the mixed uniformly scheme of absolute ideal
It is not present, is especially the SCR system that non-gas helps, spray particle diameter is larger, and spraying distribution has the characteristic of oneself, it is necessary to design again
Special mixing arrangement is prevented from crystallizing and realized well mixed.Such as the scheme having is deliberately blast pipe bending, in pipe bent position
DEF nozzles are installed, and blender is set, liquid spray is ejected on blender first.But this brings limit to blast pipe arrangement
System, blast pipe manufacturing cost can also increase.If being mounted directly DEF nozzles on the blast pipe of straight tube, can only be necessarily：
Angular injection, spraying are difficult to uniform directive blender, and as a result crystallizing risk will increase, and ammonia nitrogen is than the uniformity also than relatively low；
Nozzle is deep near blast pipe inside center, but this can cause the nozzle inside blast pipe heated serious, no
Only nozzle is easily damaged, and structure complicates, and more crucially also likely results in nozzle interior when reactant is DEF
DEF dries out and produces urea crystals too early, plug nozzle.
The content of the invention
The present invention in view of the above-mentioned problems, purpose be to provide one kind can reduce crystallization risk in the exhaust pipe of engine,
Improve reactant and be vented the SCR exhaust mixing arrangements of mixture homogeneity, while reduce SCR system cost.
To achieve the above object, the present invention takes following technical scheme：
A kind of reactant exhaust mixing arrangement of SCR system, including a reactant nozzle, an exhaust mixing tube, one
Individual reflecting plate, a blender, it is characterised in that：The exhaust mixing tube is straight tube, and the blender and reflecting plate are positioned at row
In gas mixing tube, blender and blast pipe are co-axially mounted fixation, reflecting plate be located at blender upstream and with blast pipe axis substantially
Parallel fixation, nozzle mounting surface, the nozzle mounting surface are provided with the exhaust mixing tube, positioned at the position of blender upstream
With being vented mixing tube axis bevel, the reactant nozzle is arranged on the nozzle mounting surface, and the reactant ejected is penetrated
Direction and the flow direction of exhaust gases bevel being vented in mixing tube are flowed, the jet of taper diverging sprays to the blender and reflection
Plate.
According to above-mentioned technical proposal, although reactant jet be merely able to it is oblique be sprayed onto blender, and because reactant is penetrated
Stream may have larger diffusion cone angle, and typically just top half reactant can be reached directly on blender, but lower half
The reactant divided can first collide reflecting plate, blender be reached again by reflecting resilience, so as to prevent the latter half reactant mistake
Divide the bottom wall for focusing on mixing tube.Transition concentrates on the reactant of bottom wall, even if after flowing through blender, will also result in
Larger reactant distribution is uneven.Especially DEF liquid reactants, also exist and increase macrocrystalline risk, reason is：Collision
The excessive DEF of tube wall is mixed, strong cooling is necessarily produced to tube wall, and outer tube wall is natively because radiating temperature ratio greatly
Delivery temperature is low, causes the local temperature at the rebuffed position of reactant relatively low, and DEF pyrolysis is that the speed of ammonia is greatly reduced, and is formed
The chemical time of crystalline material will lengthen, and because the boundary layer influence of near wall, always there is part flowing velocity
Very low, crystalline particle thing is just difficult to be blown away by air-flow, so crystallization risk increase.
DEF is after by engine exhaust or the heating of blast pipe wall, and can dry out precipitated urea crystalline particle first, but such as
Fruit temperature is sufficiently high, i.e. the gasification temperature higher than urea, then is not in urea crystals particle and is directly becoming gaseous state urea.It is high
Warm urea and vapor reaction will be pyrolyzed as ammonia and carbon dioxide.Meanwhile urea can also carry out other chemical reactions, generation
The crystalline solid such as biuret, cyanuric acid, melamine, but speed of the speed of these reactions than urea pyrolysis for ammonia
Slowly, when DEF does not contact lower temperature solid wall surface, crystalline solid will not accumulate.When two-phase flow speed is sufficiently large, crystalline solid is
Making to be formed can also flow away with exhaust, will not also accumulate.
Therefore, technical scheme, reactant is prevented by the higher reflecting plate of the temperature in exhaust middle part
It is directly injected on mixing tube wall, while prevents considerable fraction of reactant accumulation to be caused on mixing tube part tube wall
Serious skewness, after reflection reach blender reactant be relatively evenly distributed on blender, then by mixing
Device mixes, and the exhaust reaction agent in the exhaust mixing tube in blender downstream can just reach well mixed.
Following technical scheme, is further limited or optimizes to the present invention.
The injection stream center line intersects with the exhaust mixing tube center line, and the plane formed is by reflecting plate and mixes
Clutch is divided into the rear virtual extended line along line of symmetrical two parts, the nozzle vent central point and the reflecting plate,
It is located at the foot position of blender with the intersection point of the blender, the reactant that such nozzle sprays will not be just directly sprayed onto completely
Mixing tube bottom wall, all reactants are divided into two parts, and most directly sprays to blender, and another fraction sprays to instead
Penetrate plate and blender is reached after reflection.
Further, in structure design, the nozzle mounting position is close to mounting surface and exhaust mixer intersection one end, nozzle
The jet cone that injection is formed, before blender or reflecting plate is reached, is completely in free state, not by any solid wall surface
Stop.This is to prevent injection stream to be first sprayed onto the relatively low wall of other wall, particularly temperature, such as nozzle mounting surface institute
The peripheral wall surface of the pit at place, to avoid unnecessary reactant integrated distribution or crystallization.
In order to prevent stagnant area occur in reflection back, so as to cause crystallization to accumulate, more excellent technical scheme is by institute
State reflecting plate or reflecting plate effectively receive reactant spraying second half section (the exhaust stream port of export) (mixed the reverse side of nozzle to following
Close tube wall direction) bending certain angle, bending angle is no more than 15 °.
Reflexed to for the jet on reduction reflecting plate after the mixing tube of side and gather temperature again than relatively low wall angle
Place, the reflecting segment (second half section) of reflecting plate are designed to the hanging tongue shape not contacted with any solid wall surface, to reduce reflection
Radiating of the plate to mixing tube wall, the temperature of reflecting plate is improved, and the front half section of reflecting plate is fixed with exhaust mixing tube.It can use
The methods of welding, is fixed, its direction and exhaust mixing tube axis can into the angle within one 5 °, it is preceding it is high after it is low, front end is closer to spray
Mouth side, i.e. exhaust stream arrival end high point, the port of export are low.This be equally for prevent reflection back and its with tube wall junction
Crystallization is grown because of flowing stagnation.
The reflection plate thickness be not more than 3mm, rear end, or rear end and front end, from i.e. nozzle side chamfering above into knife
Mouthful.This DEF liquid for being also beneficial to be ejected into reflecting plate completely disengages reflecting plate from the edge of a knife, without because capillarity spreads
Go to form crystallization to reflection back.
The beneficial effects of the invention are as follows：In straight barrel type exhaust mixing tube convenient using mounting arrangements simple in construction, drop
Crystallization risk, raising reactant and exhaust mixture homogeneity in the low exhaust pipe of engine, while SCR system cost can be reduced.
Brief description of the drawings
Fig. 1 is the two-dimensional representation of one of the embodiment of the present invention.
Fig. 2 a and Fig. 2 b are two two-dimensional representations of the embodiment of the present invention.
Fig. 3 is three three dimensional sectional view of the embodiment of the present invention.
Fig. 4 is the schematic diagram of one embodiment of the reflecting plate in the present invention.
Embodiment
The present invention is further illustrated with reference to the accompanying drawings and examples.
It is as shown in Figure 1 one embodiment of the present of invention, what is drawn in figure is one section be connected on the exhaust pipe of engine
Mixing tube.The NOx reduction reactions agent (such as DEF) of SCR system mixes with engine exhaust in this section of mixing tube, including exhaust
Mixing tube leading portion 1, a reactant nozzle 2, a reflecting plate 8, a blender 6, mixing tube back segment 9.
Exhaust mixing tube leading portion 1 and back segment 9 are coaxially arranged straight tube, and reflecting plate 8 is in exhaust mixing tube leading portion 1
Pipe near axis is simultaneously located at the intersection of mixing tube leading portion 1 and back segment 9 with the almost parallel fixation of pipe axis, blender 6, and with
Mixing tube is co-axially mounted fixation, and therefore, reflecting plate 8 is located in the upstream of blender 6.Blender 6 will make local exhaust flowing side
The change of divergence very big to generation, therefore the exhaust that can be strongly facilitated downstream carries out quick strong mixing, while blender 6
The smooth surface of itself and higher temperature, higher surface velocity, liquid reactant evaporation flowing is also beneficial to, resistive connection crystalline substance
Ability is stronger.On exhaust mixing tube leading portion 1, provided with nozzle mounting surface 5, nozzle mounting surface 5 and the axis of exhaust mixing tube leading portion 1
Bevel, reactant nozzle 2 are arranged on nozzle mounting surface 5, the reactant jet direction ejected and exhaust mixing tube leading portion 1
Interior flow direction of exhaust gases bevel, the border of reactant jet is 11, sprays to blender 6 and reflecting plate 8, sprays to reflecting plate 8
Jet form contrajet 12 after its reflection, finally also reach the central region of blender 6, it is mixed without being gathered in exhaust
Close the bottom wall of pipe leading portion 1 and then enter back into blender edge.Therefore blender will be to almost all of reactant and row
The mixing of gas produces strong facilitation, the reactant exhaust inside exhaust mixing tube back segment 9 is quickly reached uniform
Distribution.
Injection stream center line 4 intersects with the exhaust center line of mixing tube leading portion 1, and the plane formed is by reflecting plate 8 and mixes
Clutch 6 is divided into symmetrical two parts.In the symmetrical plane of reflecting plate 8 and blender 6, because nozzle is close to nozzle mounting surface
5 with the handing-over position of exhaust mixing tube leading portion 1, end spaces is open before injection stream, and setting angle ensures that reactant jet will not
Encounter the border of nozzle mounting portion pit 10, injection stream is before blender 6 or reflecting plate 8 is reached, not by any solid
Wall stops, would not also produce crystallization deposition in solid wall surface.
The rear virtual extended line 7 along line of nozzle vent central point 3 and reflecting plate 8, the intersection point with blender 6 is positioned at mixed
The foot position of clutch 6, so as to which the injection stream above the extended line 7 will directly spray to blender 6, and remainder
Injection stream will spray to reflecting plate 8 and blender 6 is reached after reflection.It is direct thus almost to completely avoid nozzle reactant
It is ejected on the relatively low mixing tube wall of the relatively low exhaust flow rate of temperature, while enables reactant large area as far as possible again
Ground is distributed on blender.Advantageously reduce crystallization risk of the liquid reactant in blast pipe wall.
Fig. 2 a and Fig. 2 b show second embodiment of the present invention.The front half section 13 of reflecting plate 8 and exhaust mixing tube 1 are solid
It is fixed, the installation direction of reflecting plate 8 and the axis of exhaust mixing tube 1 into the low-angle β within one 5 °, it is preceding it is high after it is low.Such knot
The air-flow for making reflection back will not be separated, will not produce Stagnation zones by structure, so as to avoid the liquid D EF in exhaust from existing
These Stagnation zones crystallize and grow accumulation.Reflecting plate 8 is fixed on the tube wall in exhaust mixing tube leading portion 1 by its front half section 13
On, such as by being welded and fixed, its effective reflecting surface is its second half section 14, in order to reduce the dissipating to mixing tube wall of reflecting plate 8
Heat is narrowed the side both sides of second half section 14 with improving the temperature of the live part of reflecting plate 8, and the second half section 14 of reflecting plate turns into not
The hanging tongue shape contacted with any solid wall surface, it forms larger gap 15 with being vented between the inwall of mixing tube 1.This is same
When the reactant flow that reflexes to after the mixing tube of side of the jet that reduces on reflecting plate, for preventing reactant from gathering temperature
It is more favourable than relatively low wall angle.
Fig. 3 is the 3rd embodiment of the present invention, and reflecting plate 8 is designed to the front and rear bending plate for having a low-angle bending,
Its second half section 14 is not more than 15 ° to following bending certain angle α, bending angle.
Fig. 4 is another structure of reflecting plate, and the thickness of reflecting plate 8 is not more than 3mm, in order to reduce discharge flow resistance,
And the liquid above reflecting plate 8 is prevented because capillarity flows back to the back side of reflecting plate 8, front end inlet 16 is brought out with after
Mouthfuls 17 all from upper surface chamfer into the edge of a knife.
Above-described embodiment is merely to illustrate the essence of the present invention, but is not intended to limit the present invention.Without departing from the principle of the invention
In the case of, any modification for being made, the substitute mode such as simplify, be included within protection scope of the present invention.
Part that the present invention does not relate to is same as the prior art or can be realized using prior art.
Claims (7)
1. a kind of reactant exhaust mixing arrangement of SCR system, including a reactant nozzle, an exhaust mixing tube, one
Reflecting plate, a blender, it is characterised in that：The exhaust mixing tube is straight tube, and the blender and reflecting plate are positioned at exhaust
In mixing tube, blender is co-axially mounted fixation with blast pipe, and reflecting plate is located at blender upstream and substantially put down with blast pipe axis
Row is fixed, and on the exhaust mixing tube, is provided with nozzle mounting surface positioned at the position of blender upstream, the nozzle mounting surface and
Mixing tube axis bevel is vented, the reactant nozzle is arranged on the nozzle mounting surface, the reactant jet ejected
Direction sprays to the blender and reflecting plate with the flow direction of exhaust gases bevel in exhaust mixing tube, the jet of taper diverging.
2. the reactant exhaust mixing arrangement of SCR system as claimed in claim 1, it is characterised in that：In the injection stream
Heart line intersects with the exhaust mixing tube center line, and reflecting plate and blender are divided into symmetrical two by the plane formed
Point, the rear virtual extended line along line of the nozzle vent central point and the reflecting plate, the intersection point position with the blender
In the foot position of blender, the reactant that such nozzle sprays will not just be directly sprayed onto mixing tube bottom wall completely, own
Reactant be divided into two parts, most directly sprays to blender, and another fraction sprays to reflecting plate and reached after reflection
Blender.
3. the reactant exhaust mixing arrangement of SCR system as claimed in claim 2, it is characterised in that：The nozzle installation position
Rest against nearly mounting surface and exhaust mixer intersection one end.
4. the reactant exhaust mixing arrangement of SCR system as claimed in claim 3, it is characterised in that：The reflecting plate is effective
The second half section for receiving reactant spraying is not more than 15 ° to following bending certain angle, bending angle.
5. the reactant exhaust mixing arrangement of SCR system as claimed in claim 4, it is characterised in that：The second half section of reflecting plate
For the hanging tongue shape not contacted with any solid wall surface, to reduce radiating of the reflecting plate to mixing tube wall, reflection is improved
The temperature of plate, and the front half section of reflecting plate is fixed with exhaust mixing tube.
6. the reactant exhaust mixing arrangement of SCR system as claimed in claim 5, it is characterised in that：Before the reflecting plate
Half section of direction and exhaust mixing tube axis can be into the angles within one 5 °, and front end is closer to nozzle side.
7. the reactant exhaust mixing arrangement of SCR system as claimed in claim 5, it is characterised in that：The reflection plate thickness
No more than 3mm, at least rear end is from nozzle side chamfering into the edge of a knife.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720389721.5U CN207018067U (en) | 2017-04-14 | 2017-04-14 | The reactant exhaust mixing arrangement of engine exhaust SCR system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720389721.5U CN207018067U (en) | 2017-04-14 | 2017-04-14 | The reactant exhaust mixing arrangement of engine exhaust SCR system |
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| Publication Number | Publication Date |
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| CN207018067U true CN207018067U (en) | 2018-02-16 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201720389721.5U Withdrawn - After Issue CN207018067U (en) | 2017-04-14 | 2017-04-14 | The reactant exhaust mixing arrangement of engine exhaust SCR system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108729997A (en) * | 2017-04-14 | 2018-11-02 | 浙江福爱电子有限公司 | The reactant of engine exhaust SCR system is vented mixing arrangement |
-
2017
- 2017-04-14 CN CN201720389721.5U patent/CN207018067U/en not_active Withdrawn - After Issue
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108729997A (en) * | 2017-04-14 | 2018-11-02 | 浙江福爱电子有限公司 | The reactant of engine exhaust SCR system is vented mixing arrangement |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20180216 Effective date of abandoning: 20200131 |