KR20220161776A - Scr system and mixer for thereof - Google Patents

Abstract

The present embodiment relates to a mixer for a selective catalytic reduction (SCR) system installed in an engine exhaust pipe, and an SCR system using the same. More particularly, the present invention relates to a mixer for an SCR system and an SCR system for contacting a blade heated by a heater with urea solution in order to promote hydrolysis of urea solution.

Description

Mixer for SCR system and SCR system using the same {SCR SYSTEM AND MIXER FOR THEREOF}

This embodiment relates to a mixer for an SCR system installed in an engine exhaust pipe and an SCR system.

As a way to solve environmental problems worldwide, environmental regulations are strengthened, and in particular, the development of various technologies to control nitrogen oxides (NOx), known as precursors, is accelerating to reduce ultrafine dust, which is a big issue among various air pollutants. It is becoming. In particular, among various treatment technologies, a technology using ammonia as a reducing agent for the removal of nitrogen oxides through a selective catalytic reduction (SCR) technology with technical and economic advantages is representative.

The SCR system is a system that effectively proceeds a reduction reaction of nitrogen oxides (NOx) at a relatively low temperature of 250 to 450 ° C. by injecting a reducing agent into exhaust gas and passing it through a catalyst layer. As the exhaust gas passes through the SCR catalyst, ammonia converts nitrogen oxides into nitrogen and water through a chemical reaction (see formula below).

4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O : Reduction Example 1

NO + NO ₂ + 2NH ₃ → 2N2 + 3H ₂ O: reduction reaction example 2

6NO ₂ + 8NH ₃ → 7N ₂ + 12H ₂ O: Reduction Example 3

As shown in the chemical formula below, urea water is decomposed to produce HNCO, and HNCO generates ammonia (NH ₃ ) through a hydrolysis reaction, and in general, an SCR catalyst (eg, zeolite, Zr, Ti, etc.) It acts as a decomposition catalyst.

NH ₂ -CO-NH ₂ (g or l, Urea) ↔ NH ₃ (g) + HNCO (g) : thermal decomposition reaction

HNCO (g) + H ₂ O (g) → NH ₃ (g) + CO ₂ (g) : hydrolysis reaction

On the other hand, when the hydrolysis of the HNCO does not occur rapidly and is at a low temperature or a specific temperature, by-products are generated by HNCO. The generation of these by-products does not help in exhaust gas purification and consequently the exhaust gas purification efficiency in the SCR system will lower

NH ₂ -CO-NH ₂ + HNCO ↔ NH ₂ -CO-NH-CO-NH ₂ (Biuret): incomplete thermal decomposition reaction

NH ₂ -CO-NH-CO-NH ₂ + HNCO → CYA + NH ₃ (Cyanuric acid)

3HNCO → CYA (190℃)

NH ₂ -CO-NH-CO-NH ₂ + HNCO → Ammelide + H ₂ O

NH ₂ -CO-NH-CO-NH ₂ + HNCO → Ammeline + H ₂ O

Therefore, in order to increase exhaust gas purification efficiency in the SCR system, it is necessary to reduce by-product generation by HNCO by accelerating the hydrolysis of HNCO.

Against this background, an object of the present embodiment is, in one aspect, to provide a technique for heating the wings through a heater provided in the mixer rather than a separate external heating device in order to promote the hydrolysis of urea water.

In order to achieve the above object, in one aspect, a mixer for an SCR system according to the present embodiment includes a body portion of the mixer; a center disposed at the center of the inside of the body; a heater disposed inside the center and heating the center; an inner space formed between the body portion and the center portion and through which exhaust gas and urea water pass; and wing portions coupled to an outer surface of the central portion and heated by the heater through the central portion to heat the urea water and promote hydrolysis of the urea water passing through the internal space. includes

As described above, according to the present embodiment, the heated wings of the mixer heat the urea water, thereby promoting hydrolysis of the urea water. Accordingly, it is possible to increase the purification efficiency of nitrogen oxides included in the exhaust gas.

1 is a configuration diagram of a mixer for an SCR system according to an embodiment.
2 is a front view viewed from the side of the mixer for the SCR system of FIG. 1;
3 is a view for explaining a process in which exhaust gas and urea water pass through an internal space of a mixer according to an exemplary embodiment.
4 is a view for explaining a wing portion equipped with a heat dissipation coil.
5 is a view for explaining a wing part coated with a catalyst that promotes hydrolysis of urea water.
6 is a view for explaining a heater separated from the center of a mixer for an SCR system.
7 is a view for explaining a mixer for an SCR system to which a temperature sensor is attached.
8 is a configuration diagram of an SCR system including a mixer for the SCR system according to an embodiment.
9 is a diagram for explaining a flow process of exhaust gas and urea water in an SCR system.

Hereinafter, some embodiments are described in detail through exemplary drawings. In adding reference numerals to components of each drawing, it should be noted that the same components have the same numerals as much as possible even if they are displayed on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted.

Also, terms such as first, second, A, B, (a), and (b) may be used to describe the components. These terms are only used to distinguish the component from other components, and the nature, order, or order of the corresponding component is not limited by the term. When an element is described as being “connected,” “coupled to,” or “connected” to another element, that element is directly connected or connectable to the other element, but there is another element between the elements. It will be understood that elements may be “connected”, “coupled” or “connected”.

1 is a configuration diagram of a mixer 100 for an SCR system according to an embodiment.

Referring to FIG. 1 , the mixer 100 for the SCR system may include a body portion 110, a center portion 120, a heater 130, an inner space 140, and a wing portion 150.

The body portion 110 is a component forming the body of the mixer 100 for the SCR system.

The body portion 110 may include a central portion 120 , a heater 130 , an inner space 140 , and wing portions 150 inside the body portion 110 .

The body portion 110 may have a plurality of grooves to be coupled with the center portion 120, the heater 130, and other components through screws.

One or more sockets may be provided on an outer surface of the body portion 110 so that connection lines of the heater 130 and the temperature sensor 160 that measure temperature may come out of the body portion 110 . The heater 130 and the temperature sensor 160 may be connected to an external device of the SCR system with a connection wire coming out through a socket.

The socket includes a 1/2 inch or 1/8 inch socket, but is not limited thereto and may be configured in various ways.

The center portion 120 may be disposed inside the body portion 110 so that the center of the body portion 110 and the center of the center portion 120 coincide.

According to one embodiment, the central portion 120 may be provided on both end surfaces facing flanges for binding with the body portion 110, and may be fastened to the ends of the body portion 110 through screws. .

In addition, the wing part 150 may be coupled to the outer surface of the center part 120 disposed inside the body part 110, and the center part 120 serves as the center of the screw shape of the wing part 150. can be performed. The outer surface of the central portion 120 and the wing portion 150 may be coupled by welding, but is not limited thereto.

As the performance of the catalyst continues to be developed, it is possible to purify nitrogen oxides (NOx) even when the temperature of the SCR reactor is relatively low, about 180 ° C or higher. However, hydrolysis of urea water occurs at about 200 ~ 210 ℃, so it cannot function normally around 180 ℃.

Accordingly, the heater 130 may serve to promote hydrolysis by raising the temperature of the urea water to about 200 to 210° C., which is a temperature at which hydrolysis easily occurs.

Specifically, the heat generated from the heater 130 heats the central portion 120 and the wing portion 150, and the heated wing portion 150 heats urea water passing through the inner space 140 to perform hydrolysis. it will promote This is to increase the efficiency of purifying nitrogen oxides (NOx) of exhaust gas by allowing hydrolysis of urea water to occur before the urea water enters the SCR reactor 210.

The heater 130 may emit heat as described above. The temperature of the heater 130 may be appropriately controlled to a temperature of about 200 to 210° C. or higher at which hydrolysis of urea water is promoted.

The heater 130 may be driven by receiving power from a power supply provided separately outside the body 110 .

According to one embodiment, the connection line of the heater 130 comes out through one or more sockets provided on the outer surface of the body portion 110, and thus can be connected to a separately provided power supply.

The heater 130 may be formed in the form of a long metal pipe to heat the entirety of the center portion 120 and wing portion 150 in the mixer 100 .

The heater 130 may be disposed inside the central portion 120, and may be disposed so that the front surface of the heater 130 and the central portion 120 directly contact each other for heat transfer efficiency. Accordingly, the entirety of the central portion 120 and the wing portion 150 can be quickly heated.

According to one embodiment, the heater 130 may be a flange heater coupled with a flange for coupling with the body portion 110 . In the flange heater, the body portion 110 and the flange coupled to the heater 130 may be coupled and separated through screws. Since the heater 130 can be separated from the body 110 and managed separately, the effect of facilitating management and repair of the heater 130 is recognized.

The inner space 140 is located between the body portion 110 and the center portion 120 and refers to a space formed inside the body portion 110 .

The exhaust gas generated from the engine and the urea water injected from the urea water injector 230 pass through the mixer 100 for the SCR system through the internal space 140 .

In the inner space 140, a wing part 150 coupled to the center 120 may be disposed so that the exhaust gas passing through the inner space and the urea water may be uniformly mixed.

The diameter of the inner space 140 may be formed to be the same as or similar to the diameter of the wing portion 150 in order to control the flow of urea and exhaust gas flowing through the inner space 140 .

The wing portion 150 extends radially from the center portion 120 and may be formed as a plate-shaped wing portion having a structure having a certain curvature or as a plate-shaped wing portion having a flat structure.

Meanwhile, in one embodiment, the wing portion 150 may be formed in a screw shape around the center portion 120 within the body portion 110 .

Specifically, the screw shape of the wing part 150 means that the wing part 150 starts from an arbitrary starting point in the center part 120 and follows the direction in which exhaust gas and urea water flow, and the outer circumferential surface of the center part 120. It refers to a shape that advances in a way that wraps around.

Meanwhile, in one embodiment, the central portion 120 and the wing portion 150 coupled thereto may be disposed within the body portion 110 while being fixed without rotation.

The wing portion 150 may be heated by the heater 130 . The temperature at which the wings 150 are heated may be about 200 to 210° C. or higher, which is a temperature at which hydrolysis of urea water occurs well.

A heat dissipation coil 151 may be provided inside the wings 150 so that the heat transferred from the heater 130 can be well discharged.

Meanwhile, in one embodiment, a hydrolysis catalyst for accelerating the hydrolysis of urea water may be coated on the surface of the wing part 150 .

If the wings 150 receive heat from the heater 130 to heat the urea solution and the catalyst is coated on the surface of the wing 150 to come into contact with the urea solution passing through the internal space 140, the urea solution It can be confirmed that the effect of significantly accelerating the hydrolysis of

The wing unit 150 may be referred to as a blade, a mixing unit, a guide unit, and the like.

2 is a front view when looking at the mixer 100 for the SCR system from the side.

Referring to FIG. 2 , the body portion 110, the center portion 120, the heater 130, and the flange of the heater 130 according to an embodiment may have a cylindrical shape to have a circular cross section, but are limited thereto. It can be formed in various shapes such as rectangular, oval, etc.

The central part 120 and the heater 130 may be disposed at the center of the inside of the body part 110 by being bound to the body part 110 .

FIG. 3 is a diagram for explaining a process in which exhaust gas and urea water pass through the internal space 140 of the mixer 100 according to an exemplary embodiment.

According to one embodiment, the central portion 120 and the wing portion 150 formed in the form of a screw coupled thereto are disposed while being fixed without rotating.

In addition, the wing portion 150 formed in a screw shape passes through the internal space 140 in a three-dimensional spiral, as shown in the direction of the arrow shown in FIG. 3 according to the flow direction of the exhaust gas and urea water flowing in the internal space 140. It plays a role of guiding to do so, so that the exhaust gas introduced from the exhaust pipe 220 of the engine and the urea water injected from the urea water injector 230 are uniformly mixed.

Through this, the uniformity of the number of elements provided to the SCR reactor 210 installed on the rear side of the mixer 100 for the SCR system is improved.

During the above process, hydrolysis of urea water may be promoted by the wing portion 150 heated by the heater 130 while passing through the inner space 140 .

In addition, according to an embodiment, the hydrolysis of urea water may be promoted by coating the wing portion 150 with a catalyst that promotes hydrolysis of urea water.

4 is a view for explaining a wing portion provided with a heat dissipation coil 151.

According to one embodiment, a heat dissipation coil 151 is provided inside the wings 150, so that heat transferred from the heater 130 to the wings 150 can be smoothly discharged.

Since the heat dissipation coil 151 is provided inside the wing portion 150 to efficiently dissipate heat into the inner space 140, the efficiency of energy consumed by the heater 130 can be increased.

The heat dissipation coil 151 may be made of a material having high thermal conductivity, such as aluminum or other metals including the same.

The heat dissipation coil 151 may be heated by heat emitted by the heater 130 or directly connected to the heater 130 to be heated.

5 is a view for explaining the wing portion 150 coated with a catalyst that promotes the hydrolysis of urea water.

According to one embodiment, the surface of the wings 150 may be coated with a catalyst that promotes hydrolysis of urea water.

The hydrolysis catalyst is a catalyst that promotes the hydrolysis of HNCO generated through the thermal decomposition reaction of urea water, and zeolite, Zr, and Ti-based catalysts may be used.

In order to more effectively promote a hydrolysis reaction through a hydrolysis catalyst of urea water coated on the surface of the wing part 150, the surface area of the wing part 150 may be formed to be wide.

The surface of the wings 150 may be roughened so that the catalyst coating that promotes hydrolysis is easily formed.

If the surface of the wing portion 150 is roughened, the contact area with the catalyst coating is widened so that the coating is easily performed and the already coated catalyst is difficult to come off.

6 is a view for explaining the heater 130 separated from the center 120 of the mixer 100 for the SCR system.

The heater 130 may be separated from the mixer 100 for the SCR system.

The heater 130 may be formed in the form of a long metal pipe to heat the entirety of the center portion 120 and wing portion 150 in the mixer 100 .

According to one embodiment, as shown in FIG. 6 , the heater 130 may be a flange heater combined with a flange for binding with the body 110 . The body portion 110 may be coupled and separated through a flange coupled to the heater 130 and a screw.

7 is a view for explaining the mixer 100 for the SCR system to which the temperature sensor 160 is attached.

In the case of a typical SCR system, the temperature of the exhaust gas is measured through a separate temperature sensor provided in the exhaust pipe, and urea water is injected from the urea water injection device when the exhaust temperature is 180° C. or higher. This is to vaporize water in urea water and convert urea into ammonia (NH ₄ ) by heating.

According to one embodiment, a temperature sensor 160 may be additionally added to the mixer 100 for the SCR system, and the temperature sensor 160 controls whether or not the urea water injection device 230 sprays the urea water at the center ( 120) or to measure the temperature of the wings 150.

When the temperature of the center portion 120 and the wing portion 150 reaches about 200 to 210° C. or higher, which is a temperature for hydrolysis of urea water, urea water can be sprayed from the urea water injection device.

The temperature sensor 160 may be attached to a place for measuring the temperature of the center 120 as well as the wings 150 or other mixers 100 for the SCR system.

According to one embodiment, the connection line of the temperature sensor 160 can go out of the body portion 110 through a socket provided on the outer surface of the body portion 110, and a power supply device provided separately in addition to the mixer 100 for the SCR system. Power can be supplied through

8 is a configuration diagram of an SCR system 200 including a mixer 100 for the SCR system according to an embodiment.

Exhaust gas to be purified by the SCR system 200 according to the present embodiment may come from a vehicle, ship propulsion engine, engine for other purposes, or equipment emitting exhaust gas such as a boiler or an incinerator installed in a land plant.

The mixer 100 for the SCR system may be disposed at a front end of the SCR reactor 210 or at a predetermined interval from the front end of the SCR reactor 210 .

The SCR reactor 210 may include a catalyst activated by exhaust gas therein.

In the SCR reactor 210, ammonia (NH ₄ ) generated by hydrolysis of urea water reacts with nitrogen oxide (NOx) to produce nitrogen (N ₂ ) and water (H ₂ O).

When the temperature of the center portion 120 and the wing portion 150 reaches about 200 to 210° C. or higher, which is a temperature for hydrolysis of urea water, urea water can be sprayed from the urea water injection device.

9 is a diagram for explaining a flow process of exhaust gas and urea water in the SCR system 200.

The exhaust gas coming from the exhaust pipe 220 connected to the front of the urea water injector 230 and the urea water injected from the urea water injector 230 are evenly mixed by the SCR system mixer 100 according to the present embodiment.

Exhaust gas before nitrogen oxides (NOx) are purified passes through the exhaust pipe 220 connected to the front of the urea water injection device 230, and nitrogen oxides (NOx) are purified through the exhaust pipe 220 connected to the rear of the SCR reactor 210. exhaust gas will pass through.

In the mixer 100 for the SCR system, the exhaust gas from the exhaust pipe 220 connected to the front of the urea water injector 230 and before nitrogen oxides (NOx) are purified are mixed with the urea water injected from the urea water injector 230. .

The urea water that has passed through the mixer 100 for the SCR system is heated by the wings 150 heated by the heater 130 before being put into the SCR reactor 210, and is coated on the wings 150. Hydrolysis is promoted by contacting with a hydrolysis catalyst in the presence of water, and ammonia can be rapidly produced. As a result, it contributes to improving the nitrogen oxide purification efficiency of the SCR system.

Specifically, when ammonia is generated by rapidly hydrolyzing urea water in the mixer 100 for the SCR system, the ammonia is filled more quickly in the SCR reactor 210 to improve nitrogen oxide purification efficiency. 150), and the hydrolysis of HNCO generated through the thermal decomposition reaction of urea water by the hydrolysis catalyst is promoted to reduce the production of by-products generated by HNCO, the by-products of the SCR system in the SCR reactor 210 It is possible to prevent deterioration of the purification function.

In addition, the technique of providing a heater in the mixer, such as the mixer 100 for the SCR system according to the present embodiment, to increase the nitrogen oxide purification efficiency of the SCR system, can be applied not only to the chamber-type mixer but also to the blade-type mixer.

In the SCR system using existing urea water, most of the urea should be converted to NH ₃ at the front of the SCR reactor and there is a need to have a uniform flow distribution. The present invention has the advantage of significantly reducing the emission of nitrogen oxides by configuring a mixer for an SCR system for reducing nitrogen oxides to meet these requests, thereby maximizing the generation of NH ₃ and flow uniformity at the front end of the SCR reactor. provides

In addition, according to the present embodiment, there is no need to separately provide a heating device for heating urea water in the SCR system, thereby minimizing the addition of the device, thereby improving productivity and providing economic benefits.

Terms such as "comprise", "comprise" or "having" described above mean that the corresponding component may be inherent unless otherwise stated, and therefore do not exclude other components. It should be construed that it may further include other components. All terms, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs, unless defined otherwise. Commonly used terms, such as terms defined in a dictionary, should be interpreted as consistent with the meaning in the context of the related art, and unless explicitly defined in the present invention, they are not interpreted in an ideal or excessively formal meaning.

The above description is merely an example of the technical idea of the present invention, and various modifications and variations can be made to those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed according to the claims below, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

100: mixer
110: body part
120: center
130: heater
140: inner space
150: wing part
151: heat dissipation coil
160: temperature sensor
200: SCR system
210: SCR reactor
220: exhaust pipe
230: urea water injector

Claims (15)

mixer body;
a center disposed at the center of the inside of the body;
a heater disposed inside the center and heating the center;
an inner space formed between the body portion and the center portion and through which exhaust gas and urea water pass; and
a wing portion coupled to an outer surface of the central portion and heated by the heater through the central portion to heat the urea water and promote hydrolysis of the urea water passing through the inner space;
Including, mixer for the SCR system. According to claim 1,
The wing portion forms a screw shape around the center, the mixer for the SCR system. According to claim 2,
The mixer for the SCR system, which does not rotate, and allows the urea water and the exhaust gas to flow along the screw-shaped wing in the inner space. According to claim 1,
A mixer for an SCR system equipped with a heat dissipation coil inside the wing. According to claim 4,
The mixer for the SCR system, wherein the heat dissipation coil is made of aluminum. According to claim 1,
In order to help remove nitrogen oxides contained in the exhaust gas, a catalyst for promoting hydrolysis of the urea water is coated on the wings, the mixer for the SCR system. According to claim 6,
A mixer for an SCR system in which the surface of the wings is roughened so that the catalyst coating is easily performed. According to claim 1,
A mixer for an SCR system in which a temperature sensor capable of measuring the temperature of the center is attached to the center. According to claim 1,
The heater is separable from the mixer, the mixer for the SCR system. An SCR reactor, which is a device for removing nitrogen oxides contained in exhaust gas;
Exhaust pipes connected to the front and rear sides of the SCR reactor to allow the exhaust gas to pass through;
a mixer formed in the exhaust pipe connected to the front of the SCR reactor; and
A urea water injection device formed between the mixer and the exhaust pipe connected to the front of the SCR reactor;
including,
The mixer includes a wing portion heated by a heater provided in the mixer to promote hydrolysis of the urea water sprayed from the urea water injection device. According to claim 10,
The wing of the mixer forms a screw shape along the center provided in the mixer, the SCR system. According to claim 11,
The wing portion does not rotate, and the urea water and the exhaust gas flow along the screw-shaped wing portion in the inner space of the mixer. According to claim 10,
A temperature sensor is attached to a central portion provided in the mixer to which the wings are coupled, the SCR system. According to claim 10
In order to help remove nitrogen oxides contained in the exhaust gas, a catalyst that promotes hydrolysis of the urea water is coated on the wings, the SCR system. 15. The method of claim 14,
The SCR system, wherein the surface of the wings is roughened so that the catalyst coating can be easily performed.

Images