WO2017155150A1

WO2017155150A1 - Reductant mixing device

Info

Publication number: WO2017155150A1
Application number: PCT/KR2016/002871
Authority: WO
Inventors: 정종화; 양재욱
Original assignee: 세종공업 주식회사
Priority date: 2016-03-07
Filing date: 2016-03-22
Publication date: 2017-09-14
Also published as: KR101744797B1; CN108350782B; CN108350782A

Abstract

A reductant mixing device according to the present invention comprises: a housing having an exhaust gas inflow part provided at a front end side thereof and a selective catalytic reduction catalyst provided at a rear end side thereof; a reductant injection nozzle for spraying a reductant aqueous solution between the exhaust gas inflow part and the selective catalytic reduction catalyst in an inner passage of the housing; and a swirl unit mounted between the exhaust gas inflow part and the selective catalytic reduction catalyst in the inner passage of the housing so as to guide, in a spiral shape, the flow direction of the fluid in which exhaust gas and reductant aqueous solution particles are mixed, wherein a cross sectional area of a passage of the swirl unit is formed to be smaller than a cross sectional area of the passage of the housing. If the reductant mixing device according to the present invention is used, the exhaust gas flows in a spiral shape when the reductant aqueous solution is mixed in the exhaust gas discharged from a vehicle engine, a vortex is generated while the exhaust gas flows along a spiral flow path, such that the reductant aqueous solution can be more uniformly mixed in the exhaust gas, and a mixing space having a long pipe shape is provided in a spatially compressed mixing form such that the device can be mounted even in a narrow available space.

Description

Reducing agent mixing device

The present invention relates to a reducing agent mixing apparatus for efficiently mixing an aqueous solution of a reducing agent by spirally discharging an exhaust gas discharged from an engine of a vehicle. More specifically, the present invention relates to a reducing agent mixing apparatus for efficiently mixing a reducing agent aqueous solution, To a reductant mixing device capable of preventing the phenomenon of being adhered to the outermost wall.

Generally, the exhaust gas discharged from the engine is guided to a catalytic converter disposed in the middle of the exhaust pipe, purified, passed through the muffler, attenuated in noise, and then discharged to the atmosphere.

This exhaust line is installed in an internal combustion engine (e.g., a diesel engine) and includes a system for reducing nitrogen oxides and a reducing agent (e.g., a reducing agent aqueous solution) injector disposed upstream of the system. The elemental injection zone of the most common configuration is generally located between the upstream particle filter (with an oxidation catalyst in front of it) and the downstream selective oxide reduction catalyst (Selective Catalytic Reduction; SCR). According to another fairly common approach, an impregnated particle filter or a conventional particle filter for treating the oxidation catalyst and nitrogen oxide reduction places a reducing agent injection zone between the SCRs next.

In order to ensure the correct operation of the reducing agent injection, it is necessary to ensure the function of injecting and evaporating the reducing agent and the function of mixing the reducing agent and the exhaust gas so that the reducing agent is uniformly dispersed in the exhaust gas from the suction surface of the downstream block. At this time, it takes a certain time to mix the reducing agent and the exhaust gas, so that a path through which the reducing agent and the exhaust gas are in contact with each other is required to be considerably long.

An exhaust line having an injection system configured to induce the exhaust gas to rotate to the outside and inject a reducing agent into the exhaust gas so that the contact path between the reducing agent and the exhaust gas can be increased as described above (Korean Patent Laid- 0053494) has been proposed.

However, if the exhaust gas is simply rotated to the outside, the contact path between the reducing agent and the exhaust gas is not sufficient, and there is a limit in increasing the efficiency of mixing the reducing agent and the exhaust gas.

When the exhaust gas rotates to the outside, the reducing agent particles mixed in the exhaust gas come into contact with the outermost wall by centrifugal force. Since the outermost wall is relatively low in temperature, the reducing agent particles in contact with the outermost wall remain in a droplet state May occur.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made in order to solve the above problems, and it is an object of the present invention to provide an exhaust gas purifying apparatus, By generating the eddy current through the swirl unit while flowing along the helical flow path, it is possible to mix the reducing agent aqueous solution more uniformly into the exhaust gas, suppress the phenomenon that the reducing agent remains in the droplet state on the wall surface, Which is capable of being mounted in a narrow clearance space by providing a mixed space spatially compressed.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a reductant mixing apparatus comprising: a housing having a discharge gas inflow section at a tip end thereof and a selective reduction catalyst at a rear end thereof; A reducing agent spray nozzle for spraying a reducing agent aqueous solution between the exhaust gas inlet and the selective reduction catalyst in the inner flow path of the housing; And a flow path which is installed between the exhaust gas inlet and the selective reduction catalyst in the inner flow path of the housing and guides the flow direction of the mixed fluid of the exhaust gas and the reducing agent aqueous solution particles spirally from the outside to the center, Wherein the fluid passing through the inner flow path of the swirl unit is configured to flow in the longitudinal direction of the inner flow path of the swirl unit while generating a vortex in a direction wrapping the inner flow path center line of the swirl unit.

Wherein the swirl unit comprises a first block mounted to cross the inner side surface of the housing and a second block coupled to cover a front end side of the first block, And a center protruding portion protruding toward the exhaust gas inflow portion and having an opening formed at one side of the side wall, wherein the second block includes a center protruding portion including a point where the opening is formed, And a top plate connecting the top end of the side plate and the top end of the center projecting portion. The side plate is disposed on the edge of the center projecting portion.

The swirl unit includes the edge portion, the side wall of the center projecting portion, the other widthwise end of the side plate, and a mixing gas inlet portion surrounded by the upper plate. The reducing agent spray nozzle injects the reducing agent aqueous solution toward the mixing gas inlet portion Respectively.

At least one through hole is formed at a position corresponding to the inner surface of the side plate of the upper plate.

One end in the width direction of the side plate is coupled to a position corresponding to one side edge of the opening.

A plurality of fastening protrusions are formed at the lower end of the side plate, and the fastening recesses are formed at the edge portions to fasten the fastening protrusions.

When the reducing agent mixture is mixed with the exhaust gas discharged from the engine of the vehicle, the exhaust gas is spirally moved toward the center from the outer periphery, and the exhaust gas flows through the vortex flow path while flowing along the spiral flow path. The reducing agent aqueous solution can be more uniformly mixed with the exhaust gas.

Further, it is possible to minimize the phenomenon that the reducing agent remains in a droplet state on the wall surface by blocking the contact of the reducing agent to the outermost wall having a low temperature through the housing, and it is possible to minimize the residual of the reducing agent in the droplet state, It has the advantage of being able to be mounted in a narrow space.

1 and 2 are a perspective view and a longitudinal sectional view of a reducing agent mixing apparatus according to the present invention.

3 and 4 are perspective views of a swirl unit included in the reducing agent mixing apparatus according to the present invention.

5 is an exploded perspective view of the swirl unit included in the reducing agent mixing apparatus according to the present invention.

FIG. 6 shows the flow direction of the exhaust gas and the reducing agent aqueous solution in the reducing agent mixing apparatus according to the present invention.

Fig. 7 shows a shape in which a vortex is formed in a direction across the internal flow path of the swirl unit.

FIG. 8 shows an exhaust gas flow pattern realized by a conventional reducing agent mixing apparatus and an exhaust gas flow pattern realized by a reducing agent mixing apparatus according to the present invention.

Hereinafter, embodiments of a reducing agent mixing apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

The reducing agent mixing apparatus according to the present invention is a device for mixing a reducing agent aqueous solution (for example, a urea aqueous solution) with a DPF (Diesel Particulate Filter) coated with a selective reduction catalyst or a selective reduction catalyst, And is characterized in that the exhaust gas is spirally moved toward the center from the outer periphery so that the injected reducing agent aqueous solution is not concentrated in any part but is evenly distributed over the entire flow path of the exhaust gas.

That is, the reducing agent mixing apparatus according to the present invention comprises a duct structure having an internal passage so that exhaust gas discharged from an engine can pass therethrough, and an exhaust gas inlet 110 is provided at a front end side (right side in FIG. 2) A housing 100 having a catalyst mounting part 120 in which SDPF (a DPF 10 coated with a selective reduction catalyst) is inserted and inserted into the housing 100 (left side in FIG. 2) A reducing agent spray nozzle 200 for spraying the reducing agent spray nozzle 200 between the nozzle 110 and the catalyst mount 120 and a spraying path of the reducing agent spray nozzle 200 in the inner flow path of the housing 100 200) on which the swirl unit 300 is mounted.

The swirl unit 300 is a unit that spirally flows a fluid (hereinafter, referred to as 'mixing gas') mixed with an exhaust gas and a reducing agent aqueous solution particle to increase the contact time between the aqueous solution of the reducing agent and the exhaust gas, To be mixed with the gas. Thus, when the exhaust gas flows in a spiral form, the contact time with the reducing agent aqueous solution is increased, the reducing agent aqueous solution particles can be mixed evenly, and the reducing agent aqueous solution particles are evenly contacted over the entire surface of the SDPF, .

In addition, the swirl unit 300 included in the present invention flows in a spiral manner so that the exhaust gas passing through the internal flow path does not flow in a spiral shape having the same turning radius but gradually decreases in the turning radius, And the vortex is generated so as to surround the vortex generator. Such characteristics will be described in detail below with reference to separate drawings.

3 and 4 are perspective views of the swirl unit 300 included in the reducing agent mixing apparatus according to the present invention, FIG. 5 is an exploded perspective view of the swirl unit 300 included in the reducing agent mixing apparatus according to the present invention, Shows the direction in which the exhaust gas and the reducing agent aqueous solution flow in the reducing agent mixing apparatus according to the present invention. At this time, the edge portion 312 is omitted in FIG. 6 so that the flow direction of the exhaust gas passing through the swirl unit 300 is clearly shown.

When the swirling flow radius of the vortex formed through the swirl unit 300 is the same as the inner diameter of the housing 100, when the exhaust gas and the reducing agent aqueous solution particles rotate along the vortex, So that the reducing agent aqueous solution particles can not be uniformly contacted over the entire SDPF and the NOx reduction efficiency is lowered accordingly. As described above, when the entire reducing agent aqueous solution particle is not transferred to SDPF and some of the reducing agent aqueous solution particles are buried in the inner wall of the housing 100, the amount of the reducing agent aqueous solution injected from the reducing agent injection nozzle 200 and the amount of the reducing agent aqueous solution particle on the surface of the SDPF There is a difference in the amount of the contacted reducing agent aqueous solution particles, which makes it difficult to set the amount of the reducing agent aqueous solution injection, and also unnecessarily wastes the aqueous reducing agent solution, thereby increasing the maintenance cost.

Therefore, it is preferable that the vortex flow formed through the swirl unit 300 is set so as to form a vortex pattern in which the turning radius gradually decreases.

That is, the swirl unit 300 includes a first block 310 mounted to cross the inner surface of the housing 100, a second block 320 coupled to cover the front end of the first block 310, So that the mixing gas mixed with the exhaust gas and the reducing agent aqueous solution particles flows along the space between the first block 310 and the second block 320 to form a swirling vortex. The first block 310 includes an edge portion 312 having an outer end coupled to an inner side surface of the housing 100 and an opening portion 316 protruding toward the exhaust gas inlet portion 110, And a center protruding portion 314 formed with the center protrusion 314. The second block 320 is erected on the edge portion 312 so as to surround a portion of a side wall of the center protrusion 314 including a point where the opening 316 is formed, and one side of the center protrusion 314 A side plate 322 which is in close contact with the side wall and is spaced apart from the side wall of the center projecting portion 314 and a top plate 324 which connects the upper end of the side plate 322 and the upper end of the center projecting portion 314 do. The swirling unit 300 has a mixing gas inflow portion 326 surrounded by the edge portion 312, the side wall of the center projecting portion 314, the other widthwise end of the side plate 322 and the upper plate 324, .

When the swirl unit 300 is formed as described above, the exhaust gas flowing into the housing 100 through the exhaust gas inlet 110 flows into the swirl unit 300 as shown by the alternate long and two- The mixture is mixed with the reducing agent aqueous solution and then discharged through the opening 316 to the catalyst mounting part 120 side through the space between the side plate 322 and the center projecting part 314 do. At this time, the exhaust gas is spirally rotated while passing through the spacing space between the side plate 322 and the center protrusion 314, so that the spiral flow is maintained even when the exhaust gas is discharged toward the catalyst mounting part 120. Therefore, the reducing agent aqueous solution particles injected from the reducing agent injection nozzle 200 are in contact with the exhaust gas for a long time until reaching the SDPF 10, so that they can be uniformly and effectively mixed with the exhaust gas, thereby maximizing the NOx reduction efficiency.

Since the temperature of the outside of the housing 100 through which the exhaust gas flows inward is very low compared to the inside of the housing 100, when the reducing agent aqueous solution particles directly contact the wall surface of the housing 100 during the mixing of the reducing agent, There is a problem that it is easily attached. However, in the reducing agent mixing apparatus according to the present invention, since the reducing agent mixing is performed between the first block 310 and the second block 320 of the swirl unit 300, the reducing agent aqueous solution contacts the inner wall of the housing 100, Since the first block 310 and the second block 320 have a very high temperature compared to the inner wall of the housing 100, there is an advantage that droplet phenomenon of the reducing agent aqueous solution does not occur. That is, it is possible to minimize the phenomenon that the reducing agent remains in the droplet state on the wall surface by originally blocking the contact of the reducing agent with the outermost wall having a low temperature through the housing.

If the reducing agent aqueous solution particles are not adhered to the inner wall of the housing 100, the amount of the reducing agent aqueous solution particles sprayed from the reducing agent spray nozzle 200 and the amount of the reducing agent aqueous solution particles brought into contact with the surface of the SDPF disappear, The setting can be facilitated, unnecessary waste of the reducing agent aqueous solution can be prevented, and the maintenance cost can be reduced.

On the other hand, the mixing gas in which the exhaust gas and the reducing agent aqueous solution particles are mixed flows into the mixing gas inflow portion 326 provided at one side of the swirl unit 300 to form a vortex, 316 to flow in a spiral pattern in which the turning radius gradually decreases. Therefore, the phenomenon that the reducing agent aqueous solution particles adhere to the inner wall of the housing 100 due to the centrifugal force can be further reduced, and the effect that the reducing agent aqueous solution particles are evenly distributed over the entire inner flow path of the housing 100 can be obtained. In addition, when the mixing gas flows in a spiral pattern in which the turning radius of the mixing gas gradually decreases, the flowability of the mixing gas becomes higher, and the mixing gas can flow in a spiral manner very far, thereby further enhancing the mixing effect of the reducing agent aqueous solution .

On the other hand, if the injection direction of the reducing agent injection nozzle 200 is set to face the side plate 322 or the center projecting portion 314, the reducing agent aqueous solution particles are buried in the swirl unit 300 and wasted, There is a problem in that the mixing efficiency of the mixture is low.

Therefore, it is preferable that the reducing agent spraying nozzle 200 is mounted to spray the reducing agent aqueous solution toward the mixing gas inlet 326 as indicated by the solid line arrow in FIG. When the injection direction of the reducing agent injection nozzle 200 is set so as to face the mixing gas inlet 326, there is an advantage that the phenomenon of the reducing agent aqueous solution particles being buried on the surface of the swirl unit 300 and being wasted can be minimized.

Since the cross-sectional area of the flow path of the mixing gas inlet 326 is smaller than that of the housing 100, when the exhaust gas flowing inside the housing 100 flows into the mixing gas inlet 326, The flow velocity is dramatically improved. As described above, when the reducing agent spray nozzle 200 is configured to spray the reducing agent aqueous solution particles toward the mixing gas inlet 326, the reducing agent aqueous solution particles are sucked into the mixing gas inlet 326 at a very high speed, It is possible to expect the advantage that the reducing agent aqueous solution particles and the exhaust gas can be mixed more efficiently.

In addition, a certain level of exhaust gas back pressure is generated between the front side and the rear side of the swirl unit 300. If such a back pressure is generated so as to exceed the reference value, the exhaust gas generated in the engine can not be exhausted smoothly, There is a problem that various vibrations and noises may be generated.

Therefore, at least one through hole 328 may be formed in the upper plate 324 of the swirl unit 300. When the through hole 328 is formed in the upper plate 324 as described above, a part of the exhaust gas flowing through the housing 100 passes through the swirl unit 300 through the mixing gas inlet 326, And the remaining part can flow directly to the opening 316 through the through hole 328, so that the back pressure can be reduced to a certain level.

When the through hole 328 is formed at a position corresponding to the inner side surface of the side plate 322 of the upper plate 324 as shown in this embodiment, It is possible to prevent the phenomenon that the reducing agent aqueous solution contained in the mixing gas adheres to the inner side surface of the side plate 322.

Although the shape of the through hole 328 is curved along the edge of the upper plate 324 in the present embodiment, the shape, position, and number of the through hole 328 are not limited to the exhaust pressure Or the size of each part of the swirl unit 300, and the like.

5), the mixing gas introduced through the mixing gas inlet portion 326 flows through the opening portion 316 (see FIG. 5) to the outside of the opening portion 316, A turbulent flow is generated in a corner formed between one end in the width direction of the side plate 322 and one side edge of the opening 316 when passing therethrough, so that the flow of the mixing gas may not be smooth. Accordingly, one end in the width direction of the side plate 322 is preferably coupled to a position corresponding to one side edge of the opening 316.

A plurality of fastening protrusions 323 are formed at the lower end of the side plate 322 so that the coupling position between the first block 310 and the second block 320 can be constantly guided. May be formed with a coupling groove 313 to which the coupling protrusion 323 is coupled. When the fastening protrusion 323 and the fastening groove 313 are formed as described above, the second block 320 is accurately coupled to the first block 310 only by inserting the fastening protrusion 323 into the fastening groove 313 Therefore, there is an advantage that the assembling failure of the swirl unit 300 can be reduced.

When the fastening protrusion 323 is inserted into the fastening groove 313 as shown in this embodiment, the contact area between the first block 310 and the second block 320 is increased. Therefore, There is also an advantage that the coupling force between the first block 310 and the second block 320 is remarkably improved when the first block 310 and the second block 320 are coupled with each other.

FIG. 7 shows a shape in which a vortex is formed in a direction transverse to the internal flow path of the swirl unit, and FIG. 8 is a plan view of the exhaust gas flow pattern realized by the conventional reducing agent mixing apparatus and the reducing agent mixing apparatus according to the present invention And shows an exhaust gas flow pattern.

The longitudinal direction of the internal flow path of the swirl unit 300 is arranged at right angles to the flowing direction of the mixing gas flowing through the exhaust gas inlet portion 110. The exhaust gas flowing into the mixing gas inlet portion 326 is swirl The center protrusion 314 and the edge portion 312 and the side plate 322 and the top plate 324 in order not to flow in the longitudinal direction of the inner channel of the unit 300 but to sequentially pass the center protrusion 314 and the edge portion 312, (Flow along arrowed double-dotted line arrows in FIGS. 3 to 5) as a whole while generating a vortex, which is advantageous in that the reducing agent aqueous solution can be mixed more effectively and effectively.

8 (a), the exhaust gas flows in a spiral shape having the same turning radius. However, when the reducing agent mixing apparatus according to the present invention is used, as shown in FIG. 8 (b) As shown in FIG. 5A, the swirling pattern is formed so as to form a spiral pattern in which the swirling pattern gradually decreases in size, that is, the spiral pattern is formed so as to form a spiral from the outer periphery to the center. As a result, the flow efficiency of the exhaust gas is remarkably improved. There is an advantage that it is remarkably improved.

Meanwhile, in order for the reducing agent aqueous solution to be uniformly mixed with the exhaust gas, the distance through which the aqueous solution of the reducing agent and the exhaust gas flow together must be maintained to be equal to or higher than a reference value. In the conventional reductant mixing apparatus, the flow path of the reducing agent aqueous solution and the exhaust gas, And the pipe mounted between SCR had to be very long. However, in the reducing agent mixing apparatus according to the present invention, the fluid passing through the internal flow path of the swirl unit generates a vortex in a direction wrapping the internal flow path center line of the swirl unit as shown in FIG. 8 (b) Since it flows in the longitudinal direction of the channel, a sufficient flow distance can be ensured even if the above-mentioned pipe is made short, which is advantageous in that the aqueous solution of the reducing agent can be evenly mixed with the exhaust gas. That is, it is advantageous that the long-length pipe-shaped mixed space is provided with a spatially compressed mixed shape and can be mounted in a narrow clearance space.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. It will also be appreciated that many modifications and variations will be apparent to those skilled in the art without departing from the scope of the present invention.

Claims

A housing having an exhaust gas inflow section at a tip end thereof and a selective reduction catalyst at a rear end thereof;

A reducing agent spray nozzle for spraying a reducing agent aqueous solution between the exhaust gas inlet and the selective reduction catalyst in the inner flow path of the housing; And

And a flow path which is installed between the exhaust gas inflow section and the selective reduction catalyst in the internal flow path of the housing and guides the flow direction of the mixed fluid of the exhaust gas and the reducing agent aqueous solution particles spirally from the outside to the center, ;

Including,

Wherein the fluid passing through the inner flow path of the swirl unit is configured to flow in the longitudinal direction of the inner flow path of the swirl unit while generating a vortex in a direction wrapping the inner flow path center line of the swirl unit.
A housing having an exhaust gas inflow section at a tip end thereof and a selective reduction catalyst at a rear end thereof;

A reducing agent spray nozzle for spraying a reducing agent aqueous solution between the exhaust gas inlet and the selective reduction catalyst in the inner flow path of the housing; And

And a flow path which is installed between the exhaust gas inflow section and the selective reduction catalyst in the internal flow path of the housing and guides the flow direction of the mixed fluid of the exhaust gas and the reducing agent aqueous solution particles spirally from the outside to the center, ;

Including,

Wherein the fluid passing through the inner flow path of the swirl unit is configured to flow in the longitudinal direction of the inner flow path of the swirl unit while generating a vortex in a direction wrapping the inner flow path center line of the swirl unit.
The method of claim 2,

Wherein the swirl unit has the edge portion, the side wall of the center projecting portion, the other widthwise end of the side plate, and the mixing gas inlet portion surrounded by the upper plate,

Wherein the reducing agent spraying nozzle is mounted to spray the reducing agent aqueous solution toward the mixing gas inlet.
The method of claim 2,

Wherein at least one through hole is formed at a position corresponding to an inner surface of the side plate of the upper plate.
The method of claim 2,

And one end in the width direction of the side plate is coupled to a point corresponding to one side edge of the opening.
The method of claim 2,

Wherein a plurality of fastening protrusions are formed at a lower end of the side plate and a fastening groove is formed at the edge portion to fasten the fastening protrusions.