KR101758217B1 - Reducing agent mixing apparatus having liquid drop preventing function - Google Patents

Abstract

An apparatus for mixing a reducing agent according to the present invention includes: an exhaust pipe through which exhaust gas discharged from an engine passes inside and a catalyst is mounted on a rear end side; An injector for injecting a reducing agent into a portion of the internal flow path of the exhaust pipe that is spaced a predetermined distance from a point where the catalyst is mounted; And a swirling unit installed between the injector and the catalyst in the exhaust passage to spirally flow the fluid mixed with the exhaust gas and the reducing agent particles, wherein the swirl unit is spaced apart from the inner wall of the exhaust pipe by a predetermined distance So that the exhaust gas passing between the inner wall surface of the exhaust pipe and the outer surface of the swirl unit flows linearly along the inner wall surface of the exhaust pipe.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a reducing agent mixing apparatus having a droplet prevention function,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reducing agent mixing apparatus for uniformly mixing a reducing agent to an exhaust gas flowing toward a catalyst and more particularly to a reducing agent mixing apparatus for reducing a reducing agent mixing ≪ / RTI >

The diesel engine ignites the fuel injected into the engine by self-ignition due to the temperature rise caused by the compression of the piston. In such a process, incomplete combustion occurs due to non-uniformity of fuel and air, and particulate matter (PM) such as unburned carbon is generated. This kind of smoke can cause serious diseases to the human body through respiration. Especially, with the increase of diesel vehicles, it is becoming a social problem. Such a diesel vehicle has hydrocarbon (HC), carbon monoxide (CO) Various exhaust gas post-treatment apparatuses for purifying exhaust gas by treating particulate matter (PM), nitrogen oxide (NOx), and the like have been developed.

Such an exhaust gas post-treatment apparatus includes a DOC (Diesel Oxidation Catalyst) which converts the components of hydrocarbon and carbon monoxide contained in the exhaust gas into water and carbon dioxide through an oxidation reaction by a catalyst, exhaust gas contained in the exhaust gas A DPF (Diesel Particulate Filter) that collects the same particulate matter and regenerates and combusts it by the heat of the exhaust gas, a Selective Catalytic Reduction (SCR) which reduces the nitrogen oxide contained in the exhaust gas to water and nitrogen by using a catalyst : Selective catalytic reduction device).

Particularly, although diesel engines have higher thermal efficiency and lower carbon dioxide emissions than gasoline engines, they have the disadvantage that particulate matter (PM) and nitrogen oxide (NOx) emissions are greater than those of gasoline engines. Recently, an exhaust gas aftertreatment system such as an LNT (Lean NOx Trap) or SCR system has been actively researched and developed to reduce nitrogen oxides in the exhaust gas of a diesel engine.

In the SCR system, an injector for spraying a reducing agent such as an aqueous solution of urea (UREA) is installed at the upstream end of the SCR, and the reducing agent sprayed by the injector is decomposed into ammonia, whereby nitrogen oxides in the exhaust gas are reduced It is purified by water and nitrogen.

At this time, a swirl unit for spirally flowing the exhaust gas is widely used so that the reducing agent injected through the injector can be more evenly mixed into the exhaust gas, that is, the contact distance between the exhaust gas and the reducing agent can be secured longer. When the swirl unit is used, the exhaust gas flows not in a straight line but in a spiral manner. Therefore, even if the length of the exhaust pipe is not increased, the contact distance with the reducing agent is increased. As a result, the reducing agent can be more evenly mixed with the exhaust gas do.

However, in the conventional reductant mixing apparatus, since the swirl unit is inserted in the exhaust pipe in a fitting manner, the exhaust gas flowing in a helical manner by the swirl unit is brought into contact with the inner wall of the exhaust pipe, and the reducing agent particles mixed in the exhaust gas are centrifugally There is a problem that a phenomenon of trapping in the form of droplets occurs on the inner wall of the exhaust pipe.

When the reducing agent is trapped in the form of a droplet on the inner wall of the exhaust pipe, the amount of the reducing agent mixed in the exhaust gas is reduced, thereby significantly deteriorating the exhaust gas purifying efficiency.

KR 10-0999615 B1

SUMMARY OF THE INVENTION The present invention has been proposed in order to solve the above-mentioned problems, and it is an object of the present invention to provide an exhaust gas purifying apparatus capable of mixing a reducing agent more uniformly with exhaust gas by flowing exhaust gas flowing through an exhaust pipe in a spiral manner, And a reducing agent mixing device that can prevent the reducing agent from being mixed with the reducing agent.

According to an aspect of the present invention, there is provided an apparatus for mixing reductant, comprising: an exhaust pipe through which exhaust gas discharged from an engine passes and a catalyst is mounted on a rear end; An injector for injecting a reducing agent into a portion of the internal flow path of the exhaust pipe that is spaced a predetermined distance from a point where the catalyst is mounted; And a swirling unit installed between the injector and the catalyst in the exhaust passage to spirally flow the fluid mixed with the exhaust gas and the reducing agent particles, wherein the swirl unit is spaced apart from the inner wall of the exhaust pipe by a predetermined distance So that the exhaust gas passing between the inner wall surface of the exhaust pipe and the outer surface of the swirl unit flows linearly along the inner wall surface of the exhaust pipe.

Wherein the swirl unit includes a body including a cylindrical outer tube and an inner tube drawn into the outer tube, and a swirl unit arranged radially with respect to a central axis of the body, wherein one side of the swirl unit facing the catalyst is in a circumferential direction of the outer tube And is composed of a plurality of blades bending along.

The bending angle at one side of the blade is set to 45 degrees.

The swirl unit is manufactured to have a length of 30 mm or more.

Three or more support plates are inserted between the inner wall of the exhaust pipe and the outer surface of the outer pipe so that the distance between the inner wall of the exhaust pipe and the outer surface of the outer pipe can be maintained constant.

And a guide plate extending from a front end of the outer tube toward a side to which the exhaust gas flows.

The guide plate is formed in a hollow tube shape.

The guide plate is formed so as to be inclined in its entirety or in part so that the diameter of the end in the extending direction is narrower than the point joined to the tip of the outer tube.

The guide plate is formed so that its thickness becomes thinner toward the end in the extending direction.

By using the reducing agent mixing apparatus according to the present invention, it is possible to mix the reducing agent with the exhaust gas evenly by flowing the exhaust gas flowing in the exhaust pipe in a spiral manner, and by forming the exhaust gas laminar flow on the inner wall of the exhaust pipe, It is possible to prevent the phenomenon of trapping in the form of droplets and to increase the velocity of the exhaust gas flowing through the inner wall of the exhaust pipe to more effectively prevent the droplets of the reducing agent.

1 is a vertical sectional view of a reducing agent mixing apparatus according to the present invention.
2 and 3 are a perspective view and a side view of a swirl unit included in the reducing agent mixing apparatus according to the present invention.
4 is a perspective view of a second embodiment of the swirl unit included in the reducing agent mixing apparatus according to the present invention.
5 and 6 are a perspective view and a use state view of a third embodiment of the swirl unit included in the 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.

FIG. 1 is a vertical sectional view of a reducing agent mixing apparatus according to the present invention, and FIGS. 2 and 3 are a perspective view and a side view of a swirl unit included in a reducing agent mixing apparatus according to the present invention.

The reducing agent mixing apparatus according to the present invention is an apparatus for reducing a NOx contained in an exhaust gas into hydrogen and water by injecting a reducing agent such as an urea aqueous solution into the exhaust gas. The reducing agent is not concentrated on only one side, So that it can be evenly distributed.

That is, the reducing agent mixing apparatus according to the present invention includes an exhaust pipe 100 in which exhaust gas discharged from an engine passes through the inside of the exhaust pipe 100 and a catalyst 200 is mounted on a rear end side of the exhaust pipe 100, An injector 300 for injecting a reducing agent to a position spaced a predetermined distance from a mounting point of the injector 300 and the catalyst 200 in the internal flow path of the exhaust pipe 100, And a swirl unit 400 for spirally flowing a fluid mixed with the exhaust gas and the reducing agent particles. The swirl unit 400 includes a body 410 formed of a cylindrical outer tube 412 and an inner tube 414 drawn into the outer tube 412 and a cylindrical body 410 having a center axis of the body 410, And a plurality of blades 420 arranged radially and bent toward one side of the outer tube 412 toward the catalyst 200. The exhaust gas flowing into the exhaust pipe 100 flows in a spiral manner. The swirl unit 400 is applied to the conventional reductant mixer in the same manner. The detailed description of the structure and function of the swirl unit 400 will be omitted.

At this time, when the entire exhaust gas flowing into the exhaust pipe 100 flows spirally by the swirl unit 400, when the reducing agent particles mixed in the exhaust gas spirally move along the exhaust gas, the exhaust gas 100 ), So that the phenomenon of reducing agent droplet may occur. When some reducing agent is collected in the form of droplets on the inner wall of the exhaust pipe 100, the exhaust gas flowing into the catalyst 200 side is mixed with the reducing agent below the reference value, so that the exhaust gas purification can not be normally performed.

In order to solve such a problem, most of the exhaust gas flowing into the exhaust pipe 100 passes through the swirl unit 400 and flows in a spiral manner, and flows into the exhaust pipe 100 A part of the exhaust gas is constituted to flow straightly along the inner wall surface of the exhaust pipe 100 without passing through the swirl unit 400. [ That is, the reductant mixing apparatus according to the present invention is installed not to be closely attached to the inner wall of the exhaust pipe 100 but to be spaced apart from the inner wall of the exhaust pipe 100 by a certain distance, A part of the exhaust gas flowing into the exhaust pipe 100 flows between the inner wall surface of the exhaust pipe 100 and the outer surface of the swirl unit 400 and flows straight along the inner wall surface of the exhaust pipe 100.

As described above, when a part of the exhaust gas flowing in the exhaust pipe 100 flows straight along the inner wall of the exhaust pipe 100, the reducing agent particles mixed in the exhaust gas flowing in a helical manner are discharged to the exhaust pipe 100 by the centrifugal force, Even if the exhaust pipe 100 is pushed into the inner wall of the exhaust pipe 100, the reducing agent is trapped in the form of droplets on the inner wall of the exhaust pipe 100, that is, the exhaust gas flowing along the inner wall of the exhaust pipe 100, The wetting phenomenon does not occur. At this time, if a large amount of reducing agent particles are mixed in the exhaust gas flowing on the inner wall of the exhaust pipe 100, a reducing agent droplet phenomenon may occur on the inner wall of the exhaust pipe 100. However, The reducing agent injected through the injector 300 passes through the swirl unit 400 and is not directly transmitted to the inner wall of the exhaust pipe 100 . Therefore, since the reducing agent particles are hardly mixed in the exhaust gas flowing straight through the inner wall of the exhaust pipe 100, the reducing agent rarely collects in the form of droplets on the inner wall of the exhaust pipe 100.

When the reducing agent mixing apparatus according to the present invention is used, all the reducing agent injected from the injector 300 is mixed with the exhaust gas and flows toward the catalyst 200 side, so that the efficiency of purifying the exhaust gas can be remarkably improved.

At this time, the turning radius of the exhaust gas flowing in a helical shape is determined according to the bending angle of the blade 420. If the bending angle of the blade 420 is set to be very large like a fan, the turning radius of the exhaust gas gradually increases The exhaust gas flowing in a helical shape strikes the inner wall of the exhaust pipe 100, which may cause the reducing agent particles to be collected on the inner wall of the exhaust pipe 100. Therefore, in the swirl unit 400 included in the present invention, the bending angle [theta] at one side of the blade 420 is preferably set to 45 [deg.] So that the rotating radius of the exhaust gas can be kept constant like a circulator .

In order to allow the exhaust gas passing between the inner wall surface of the exhaust pipe 100 and the outer surface of the swirl unit 400 to flow stably and linearly, the inner wall surface of the exhaust pipe 100 and the outer surface of the swirl unit 400 It is necessary to secure a certain length of the flow path between the two. Therefore, the swirl unit 400 is preferably manufactured to have a length L of 30 mm or more. When the swirl unit 400 is manufactured longer than the reference value, a certain degree of straightness is generated while the exhaust gas passes between the inner wall surface of the exhaust pipe 100 and the outer surface of the swirl unit 400, The exhaust pipe 100 can be smoothly moved along the inner wall.

4 is a perspective view of a second embodiment of the swirl unit 400 included in the reducing agent mixing apparatus according to the present invention.

If the swirl unit 400 is shaken while the exhaust gas flows inside the exhaust pipe 100, the flow rate of the exhaust gas flowing along the inner wall of the exhaust pipe 100 can not be maintained constant, .

Therefore, the reducing agent mixing apparatus according to the present invention may be configured such that the distance between the inner wall of the exhaust pipe 100 and the outer side surface of the outer pipe 412 is kept constant, the inner wall of the exhaust pipe and the outer pipe 412, Three or more support plates 430 may be inserted between the outer side surfaces of the support plates 430. [ When the support plate 430 is further provided, the outer surface of the swirl unit 400 and the inner wall of the exhaust pipe 100 are always spaced apart from each other. The straightness of the exhaust gas flowing on the inner wall of the exhaust pipe 100 Is maintained at a high level.

The support plate 430 is extended along the longitudinal direction of the exhaust pipe 100 so that the exhaust gas can enhance the straightness of the exhaust gas passing between the inner wall surface of the exhaust pipe 100 and the outer surface of the swirl unit 400. [ As shown in Fig. When the support plate 430 is formed in the shape of a flat plate, the exhaust gas flowing between the inner wall surface of the exhaust pipe 100 and the outer surface of the swirl unit 400 flows through the support plate 430, , The exhaust gas flowing on the inner wall of the exhaust gas has an advantage that a stable linear flow can be achieved even after passing through the swirl unit 400.

The number of the support plates 430 may vary depending on the pressure of the exhaust gas flowing in the exhaust pipe 100 or the pressure of the exhaust gas flowing through the support plate 430 ), And the stiffness of the stiffener.

5 and 6 are a perspective view and a use state view of a third embodiment of the swirl unit 400 included in the reducing agent mixing apparatus according to the present invention.

The reductant mixing apparatus according to the present invention may further include a guide plate 440 extending from the tip of the outer tube 412 toward the side where the exhaust gas flows. When the guide plate 440 is further provided, the straightness of the exhaust gas passing between the inner wall surface of the exhaust pipe 100 and the outer surface of the swirl unit 400 can be further improved. When the guide plate 440 is additionally provided at the tip of the outer tube 412, a phenomenon that the reducing agent injected from the injector 300 flows into the inner wall surface of the exhaust pipe 100 and the outer side surface of the swirl unit 400 The effect that the reducing agent is not trapped on the inner wall of the exhaust pipe 100 can be obtained.

When the guide plate 440 is provided only at a part of the front end of the outer pipe 412, some of the exhaust gas flowing into the space between the inner wall surface of the exhaust pipe 100 and the outer surface of the swirl unit 400, 440), the above-mentioned effects can not be obtained. Therefore, it is preferable that the guide plate 440 is formed in a hollow tube shape as shown in FIG.

As the flow rate of the exhaust gas passing between the inner wall surface of the exhaust pipe 100 and the outer surface of the swirl unit 400 increases, the straightness of the exhaust gas flowing on the inner wall of the exhaust pipe 100 increases. May be configured to increase the flow rate of the exhaust gas passing between the inner wall surface of the exhaust pipe (100) and the outer surface of the swirl unit (400). 6, the guide plate 440 may be formed so as to be inclined in its entirety or in part so that the diameter of the distal end of the guide plate 440 in the extending direction is narrower than the point of the guide plate 440 coupled to the distal end of the outer tube 412.

When the guide plate 440 is inclined in this manner, the flow rate of the exhaust gas flowing between the inner wall surface of the exhaust pipe 100 and the outer surface of the swirl unit 400 increases. As a result, the flow of the exhaust gas flowing on the inner wall of the exhaust pipe 100 The flow rate of the exhaust gas is increased.

If the guide plate 440 is formed to be inclined excessively, the flow rate of the exhaust gas flowing into the swirl unit 400 is reduced to reduce the effect of mixing the reducing agent into the exhaust gas, It is preferable that the slope of the slope is appropriately selected according to various conditions.

6), the exhaust gas flowing inside the exhaust pipe 100 collides with the end of the guide plate 440, causing a decrease in the flow velocity and generation of eddy currents . Therefore, as shown in the present embodiment, the guide plate 440 is preferably formed so as to be thinner toward the end in the extending direction.

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 invention.

100: exhaust pipe 200: catalyst
300: Injector 400: Swirl unit
410: Body 412: Outer tube
414: Inner tube 420: Blade
430: Support plate 440: Guide plate

Claims (9)

An exhaust pipe through which the exhaust gas discharged from the engine passes, and a catalyst is mounted on the rear end side;
An injector for injecting a reducing agent into a portion of the internal flow path of the exhaust pipe that is spaced a predetermined distance from a point where the catalyst is mounted; And
A swirling unit mounted between the injector and the catalyst in an internal flow path of the exhaust pipe and configured to spirally flow a fluid mixed with the exhaust gas and the reducing agent particles;
≪ / RTI >
Wherein the swirl unit is spaced apart from the inner wall of the exhaust pipe by a predetermined distance so that the exhaust gas passing between the inner wall surface of the exhaust pipe and the outer surface of the swirl unit flows straight along the inner wall surface of the exhaust pipe,
Wherein the swirl unit includes a body including a cylindrical outer tube and an inner tube drawn into the outer tube, and a swirl unit arranged radially with respect to a central axis of the body, wherein one side of the swirl unit facing the catalyst is in a circumferential direction of the outer tube And is composed of a plurality of blades bending along,
And a guide plate extending from a front end of the outer tube toward a side to which the exhaust gas flows,
Wherein the guide plate is formed so as to be inclined in its entirety or in part so that the diameter of the end of the guide plate in the extending direction is narrower than a point of the guide plate joined to the tip of the outer tube. delete The method according to claim 1,
Wherein the bending angle of one side of the blade is 45 °. The method according to claim 1,
Wherein the swirl unit is manufactured to have a length of 30 mm or more. The method according to claim 1,
Three or more supporting plates are inserted between the inner wall of the exhaust pipe and the outer surface of the outer pipe so that the distance between the inner wall of the exhaust pipe and the outer surface of the outer pipe can be kept constant,
Wherein the support plate is formed in a flat plate shape extending along the longitudinal direction of the exhaust pipe. delete The method according to claim 1,
Wherein the guide plate is formed in a hollow tube shape. delete An exhaust pipe through which the exhaust gas discharged from the engine passes, and a catalyst is mounted on the rear end side;
An injector for injecting a reducing agent into a portion of the internal flow path of the exhaust pipe that is spaced a predetermined distance from a point where the catalyst is mounted; And
A swirling unit mounted between the injector and the catalyst in an internal flow path of the exhaust pipe and configured to spirally flow a fluid mixed with the exhaust gas and the reducing agent particles;
≪ / RTI >
Wherein the swirl unit is spaced apart from the inner wall of the exhaust pipe by a predetermined distance so that the exhaust gas passing between the inner wall surface of the exhaust pipe and the outer surface of the swirl unit flows straight along the inner wall surface of the exhaust pipe,
Wherein the swirl unit includes a body including a cylindrical outer tube and an inner tube drawn into the outer tube, and a swirl unit arranged radially with respect to a central axis of the body, wherein one side of the swirl unit facing the catalyst is in a circumferential direction of the outer tube And is composed of a plurality of blades bending along,
And a guide plate extending from a front end of the outer tube toward a side to which the exhaust gas flows,
Wherein the thickness of the guide plate is reduced toward the end in the extending direction.

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