KR20210067454A - Reactor for selective catalytic reduction - Google Patents

Abstract

The present invention relates to a selective catalytic reduction reactor for reducing nitrogen oxides contained in exhaust gas. According to an embodiment of the present invention, the selective catalytic reduction reactor includes: a body unit connected to a main outlet pipe at one end and having an opening on the other side; a bypass unit integrally coupled to the other side of the body unit having the opening, communicating with the inside of the body unit through the opening, connected to a main inlet pipe at one end, and connected to the bypass outlet pipe at the other end; and a catalyst disposed between the opening and the main outlet pipe in the body unit.

Description

Selective catalytic reduction reactor {REACTOR FOR SELECTIVE CATALYTIC REDUCTION}

The present invention relates to a selective catalytic reduction reactor, and more particularly, to a selective catalytic reduction reactor used to reduce nitrogen oxides (NOx) contained in exhaust gas.

As industrialization progresses rapidly, the use of various fossil fuels such as petroleum and coal has increased. As a result, various harmful gases emitted during the combustion of fossil fuels cause serious air pollution. Typical examples include smog and acid rain.

The main culprits of air pollution include sulfur oxides (SOx) and nitrogen oxides (NOx) in exhaust gases emitted from engines of vehicles and ships, thermal power plants, factories, and the like.

In recent years, with the increasing awareness of environmental conservation, emission regulations for these sulfur oxides and nitrogen oxides have been introduced.

In particular, there is a selective catalytic reduction (SCR) system as a representative facility for reducing nitrogen oxides. The selective catalytic reduction system reacts nitrogen oxides and reducing agents contained in the exhaust gas while passing the exhaust gas and the reducing agent together through a reactor in which the catalyst is installed to reduce the nitrogen and water vapor.

When this selective catalytic reduction system is used in ships, the emission of nitrogen oxides (NOx) emitted from marine diesel engines is the 3rd International Air Pollution Prevention Regulation (IMO Tier-III) regulated by the International Maritime Organization. Therefore, an effective operation method along with a low-cost and high-efficiency denitrification facility is required.

On the other hand, due to the limited space of the ship, the selective catalytic reduction system used in the ship is required to simplify.

In general, the conventional selective reduction system used in ships includes an exhaust passage through which the exhaust gas discharged from the engine moves, and a reducing agent injection unit for injecting a reducing agent to the exhaust gas moving along the exhaust passage, and mixing the reducing agent with the exhaust gas. It includes a mixer, and a reactor in which a catalyst for selective catalytic reduction reaction is provided. And since the reducing agent injected through the reducing agent injection unit must be sufficiently mixed with the exhaust gas, a residence time is required for mixing with the exhaust gas from the point where the reducing agent is injected before reaching the reactor where the catalyst is installed. And in order to secure such a residence time, the exhaust passage from the point where the reducing agent is injected to the reactor is required to have a minimum length. Thus, forming the length of the exhaust passage to be long greatly reduces the ease of installation according to the spatial limitation when the selective catalytic reduction system is installed in a ship.

In addition, when the selective catalytic reduction system is not in operation, the exhaust gas should be separately installed as a bypass flow path for bypassing and moving the catalyst installed reactor.

As described above, as the overall configuration of the selective reduction system becomes complicated, there is a problem in that it is not easy to optimally install the selective catalytic reduction system to maximize the efficiency of the selective catalytic reduction system in a limited space such as a ship. In addition, there is a problem that maintenance becomes difficult by installing a selective catalytic reduction system having a complicated structure in a narrow space.

An embodiment of the present invention provides a selective catalytic reduction reactor with improved ease of installation and maintenance by minimizing the space required for installation by simplifying the configuration.

According to an embodiment of the present invention, the selective catalytic reduction reactor for reducing nitrogen oxides contained in exhaust gas is connected to the main discharge pipe at one end and has an opening formed on the other side thereof, and the other of the main body portion having the opening formed therein. A bypass part integrally coupled to the side and communicating with the inside of the body part through the opening, connected to the main inlet pipe at one end and connected to the bypass discharge pipe at the other end, and the opening and the main outlet pipe in the inside of the body part a catalyst disposed therebetween.

The selective catalytic reduction reactor is installed inside the bypass part adjacent to the opening of the main body, and guide vanes for diffusion and moving the exhaust gas so that the exhaust gas flowing into the interior of the main body through the opening evenly contacts the catalyst. (guide vane) may be further included.

In addition, according to another embodiment of the present invention, the selective catalytic reduction reactor for reducing nitrogen oxides contained in exhaust gas includes a body part connected to a main exhaust pipe through which exhaust gas is discharged in the first region, and installed inside the body part and one end is connected to the main inlet pipe through which exhaust gas is introduced through the second area of the body part, the other end is opened inside the body part and the other side is a bypass outlet pipe passing through the third area of the body part and a bypass unit connected thereto, and a catalyst disposed between the opening of the bypass unit and the main discharge pipe inside the body unit.

The selective catalytic reduction reactor may further include a reducing agent injection unit installed in the main inlet pipe. And the reducing agent injected from the reducing agent injection part may be mixed with the exhaust gas inside the bypass part and then introduced into the body part through the opening.

In addition, a main valve may be formed in the main discharge pipe, and a bypass valve may be formed in the bypass discharge pipe.

When the main valve is opened and the bypass valve is closed, the exhaust gas introduced into the bypass unit through the main inlet pipe may move to the main body through the opening and then may be discharged to the main discharge pipe through the catalyst. And when the main valve is closed and the bypass valve is opened, the exhaust gas introduced into the bypass unit through the main inlet pipe may be discharged to the bypass discharge pipe.

According to an embodiment of the present invention, the selective catalytic reduction reactor minimizes the space required for installation by simplifying the configuration, thereby improving the ease of installation and maintenance.

1 is a perspective view showing a selective catalytic reduction reactor according to a first embodiment of the present invention.
FIG. 2 is a perspective view showing a state in which the body part and the bypass part of the selective catalytic reduction reactor of FIG.
3 is a plan view showing the internal structure of the selective catalytic reduction reactor of FIG.
4 is a perspective view showing a selective catalytic reduction reactor according to a second embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In addition, in various embodiments, components having the same configuration are typically described in the first embodiment using the same reference numerals, and only configurations different from those of the first embodiment will be described in the second embodiment. do.

It is noted that the drawings are schematic and not drawn to scale. Relative dimensions and proportions of parts in the drawings are shown exaggerated or reduced in size for clarity and convenience in the drawings, and any dimensions are illustrative only and not limiting. In addition, the same reference numerals are used to indicate like features to the same structure, element, or part appearing in two or more drawings.

The embodiment of the present invention specifically represents an ideal embodiment of the present invention. As a result, various modifications of the diagram are expected. Accordingly, the embodiment is not limited to a specific shape of the illustrated area, and includes, for example, a shape modification by manufacturing.

Hereinafter, a selective catalytic reduction reactor 101 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3 .

The selective catalytic reduction reactor 101 according to the first embodiment of the present invention is used in a selective catalytic reduction (SCR) system for reducing nitrogen oxides (NOx) contained in exhaust gas discharged from a power plant. . For example, the power unit may be a diesel engine used as a main power source for supplying propulsion to a ship. Also, the diesel engine may be a two-stroke low-speed diesel engine for marine use.

However, the first embodiment of the present invention is not limited thereto. The power unit may be an internal combustion engine for a plant or an engine for a vehicle. That is, various types of engines known to those of ordinary skill in the art may be used as the power device.

The exhaust gas containing nitrogen oxides (NOx) discharged from the power unit moves through the exhaust passage. That is, the exhaust passage is connected to the exhaust port of the diesel engine, which is a power device, to discharge the exhaust gas of the diesel engine, and may be connected to the selective catalytic reduction reactor 101 .

1 to 3, the selective catalytic reduction reactor 101 according to the first embodiment of the present invention has a main body 300, a bypass unit 400, a catalyst 350, and a main discharge pipe 630. ), a main inlet pipe 610 , and a bypass outlet pipe 640 .

In addition, the selective catalytic reduction reactor 101 may further include a guide vane 430 , a main valve 730 , a bypass valve 740 , and a reducing agent injection unit 500 .

The main body 300 is connected to the main discharge pipe 630 at one end and an opening 304 is formed at the other side. In addition, the main body 300 may have a main body outlet 309 to be connected to the main discharge pipe (630). And the main body 300 may be formed in various types of container shapes.

The bypass part 400 is integrally coupled to the other side of the body part 300 in which the opening 304 is formed and communicates with the interior of the body part 300 through the opening 304 . And it is connected to the main inlet pipe 610 at one end of the bypass unit 400 and is connected to the bypass outlet pipe 640 at the other end. In addition, the bypass unit 400 may have an inlet 401 connected to the main inlet pipe 610 and a bypass outlet 409 connected to the bypass outlet pipe 640 .

The main inlet pipe 610 , the main outlet pipe 630 , and the bypass discharge pipe 640 are respectively connected to the exhaust flow path. That is, the exhaust gas discharged from the engine moves along the exhaust flow path and flows into the selective catalytic reduction reactor 101 through the main inlet pipe 610 , and then discharged through the main discharge pipe 630 or the bypass discharge pipe 640 . do. And the main valve 730 and the bypass valve 740 open and close the main discharge pipe 630 and the bypass discharge pipe 640, respectively.

The catalyst 350 is disposed between the opening 304 and the main discharge pipe 630 in the interior of the body part 300 . The catalyst 350 may be disposed in the form of a module, and a plurality of catalyst modules may be loaded in a direction crossing the movement direction of the exhaust gas inside the body part 300 to form a plurality of catalyst layers. The plurality of catalyst layers may be arranged to be spaced apart from each other based on the direction in which the exhaust gas moves within the main body 300 .

In addition, the plurality of catalyst modules may be formed in a hexahedron. For example, the plurality of catalyst modules may be a cuboid or a cube. When the catalyst module is formed as a cuboid or cube as described above, it is easy to load the catalyst module, as well as easy replacement and transport of the catalyst module, and the efficiency of the catalyst 350 included in the catalyst module can be maximized.

In addition, the catalyst 350 may be made of various materials known to those skilled in the art, such as zeolite, vanadium, and platinum. For example, the catalyst 350 may have an activation temperature within the range of 200 degrees Celsius to 500 degrees Celsius. Here, the activation temperature refers to a temperature at which the catalyst 350 can stably reduce nitrogen oxides without being poisoned. If the catalyst 350 reacts outside the active temperature range, the catalyst 350 is poisoned and the efficiency is lowered.

For example, when a reduction reaction to reduce nitrogen oxides contained in exhaust gas occurs at a relatively low temperature of 150 degrees Celsius or more and less than 250 degrees Celsius, sulfur oxides (SOx) of exhaust gas and ammonia (NH ₃ ) as a reducing agent reacts to form a catalyst poisoning substance. Specifically, the poisoning material for poisoning the catalyst 350 may include at least one of _{ammonium sulfate ((NH 4} ) ₂ SO ₄ ) and ammonium bisulfate (NH ₄ HSO _{4 ).} This catalyst poisoning material is adsorbed to the catalyst 350 to reduce the activity of the catalyst 350 . Since the catalyst poisoning material is decomposed at a relatively high temperature, that is, at a temperature within the range of 350 degrees Celsius to 450 degrees Celsius, the catalyst 350 in the reactor may be heated to regenerate the poisoned catalyst 350 .

_{In addition, ammonia (NH 3} ) is used as a reducing agent that directly reacts with nitrogen oxides in the catalyst 350, but it is common to use a stable aqueous urea solution because ammonia itself is not easy to store and transport as a contaminant. That is, urea, which is a reducing agent precursor, is stored, transported, and supplied in the form of an aqueous solution. Urea (urea, CO(NH ₂ ) ₂ ) aqueous solution is hydrolyzed or pyrolyzed _{to produce ammonia (NH 3} ) and isocyanic acid (HNCO). And isocyanic acid (HNCO) is again decomposed into _{ammonia (NH 3} ) and carbon dioxide (CO _{2 ).} That is, urea is decomposed to produce ammonia, which is a reducing agent that reacts with nitrogen oxides.

The guide vane 430 is installed inside the bypass unit 400 adjacent to the opening 304 of the main body 300 , and exhaust gas flowing into the main body 300 through the opening 304 . The exhaust gas may be diffusely moved so that the gas is in contact with the catalyst 350 evenly. To this end, a plurality of guide vanes 430 may be set at various angles. That is, the exhaust gas flowing into the body part 300 through the opening 304 is diffused by the guide vanes 430 to evenly contact the catalyst 350 installed inside the body part 300 .

The reducing agent injection unit 500 is installed in the main inlet pipe 610 to inject the reducing agent. And the reducing agent injected from the reducing agent injection unit 500 is mixed with the exhaust gas inside the bypass unit 400 and then introduced into the body unit 300 through the opening 304 .

As such, in the first embodiment of the present invention, the reducing agent may be mixed with the exhaust gas in the bypass unit 400 integrally formed with the body unit 300 . That is, the bypass unit 400 may perform two roles of moving the exhaust gas without going through the catalyst 350 or mixing the reducing agent with the exhaust gas.

The main valve 730 is installed in the main discharge pipe 630 to open and close the main discharge pipe (630). And the bypass valve 740 is installed in the bypass discharge pipe 640 to open and close the bypass discharge pipe (640).

In the first embodiment of the present invention, when the main valve 730 is opened and the bypass valve 740 is closed, the exhaust gas introduced into the bypass unit 400 through the main inlet pipe 610 is transferred to the bypass unit 400 . ), the reducing agent injection unit 500 is mixed with the injected reducing agent, and then moves to the body unit 300 through the opening 304 and is discharged to the main discharge pipe 630 through the catalyst 350 .

On the other hand, when the main valve 730 is closed and the bypass valve 740 is opened, the exhaust gas introduced into the bypass unit 400 through the main inlet pipe 610 directly bypasses the bypass outlet pipe (350) without passing through the catalyst (350). 640). At this time, the reducing agent injection unit 500 does not spray the reducing agent.

As such, the bypass unit 400 formed integrally with the body unit 300 becomes a space for mixing the exhaust gas and the reducing agent when the reducing agent is injected from the reducing agent injection unit 500, and when the reducing agent is not injected, the catalyst ( 350) to bypass the exhaust gas.

By such a configuration, the selective catalytic reduction reactor 101 according to the first embodiment of the present invention minimizes the space required for installation by increasing space utilization, thereby improving the ease of installation and maintenance. That is, the overall configuration can be simplified by using the bypass unit 400 as a space for mixing the reducing agent and the exhaust gas.

In addition, according to the first embodiment of the present invention, the exhaust gas introduced into the main inlet pipe 610 connected to one end of the bypass unit 400 moves in the direction of the other end inside the bypass unit 400 . Afterwards, the guide vane 430 and the opening 304 are introduced into the interior of the main body 300 . As such, since the movement direction is switched when the exhaust gas moves from the bypass unit 400 to the body unit 300 , the exhaust gas and the reducing agent can be mixed more effectively. Accordingly, a mixer for mixing the exhaust gas and the reducing agent may be omitted.

In addition, according to the first embodiment of the present invention, the reducing agent injection unit 500 and the bypass unit 400 needlessly in order to secure a residence time for the reducing agent injected from the reducing agent injection unit 500 to be mixed with the exhaust gas. There is no need to lengthen the exhaust flow path between them, and it does not matter if the reducing agent injection unit 500 is installed in a position close to the bypass unit 400 of the selective catalytic reduction reactor 101, the installation freedom of the reducing agent injection unit 500 becomes higher Therefore, the position of the reducing agent injection unit 500 can be freely set according to the size and shape of the space in which the selective catalytic reduction reactor 101 is to be installed.

Hereinafter, a selective catalytic reduction reactor 102 according to a second embodiment of the present invention will be described with reference to FIG. 5 .

As shown in Figure 5, the selective catalytic reduction reactor 102 according to the second embodiment of the present invention is a body portion 300, a bypass portion 400, a catalyst (not shown), a main discharge pipe 630, It includes a main inlet pipe 610, and a bypass outlet pipe (640).

In addition, the selective catalytic reduction reactor 102 may further include a guide vane 430 , a main valve 730 , a bypass valve 740 , and a reducing agent injection unit 500 .

The body part 300 is connected to the main exhaust pipe 630 through which exhaust gas is discharged from the first region. And the body part 300 may be formed in various types of container shapes.

The bypass unit 400 is installed inside the body unit 300 and has one end connected to the main inlet pipe 600 through which exhaust gas is introduced through the second region of the body unit 300, and the other end is connected to the main body unit. It is opened from the inside of the 300 , and one side is connected to the bypass discharge pipe 640 passing through the third region of the main body 300 .

Although the first region and the third region are formed on the same side in FIG. 4 , the second embodiment of the present invention is not limited thereto. According to the size and shape of the space in which the selective catalytic reduction reactor 101 is installed, the third region may be formed on a different side from the first region. That is, a direction in which the main discharge pipe 630 is connected to the main body 300 and a direction in which the bypass discharge pipe 640 passes through the main body 300 and is connected to the bypass unit 400 may be different.

The catalyst (not shown) may be disposed between the opening 304 and the main discharge pipe 630 in the interior of the body part 300 .

In FIG. 4, the arrow filled in black indicates the flow of exhaust gas when the main valve 730 is opened and the bypass valve 740 is closed, and the arrow filled in white is the main valve 730 is closed and the bypass valve ( 740) represents the flow of exhaust gas in the open state.

As shown in FIG. 4 , when the main valve 730 is opened and the bypass valve 740 is closed, the exhaust gas introduced into the bypass unit 400 through the main inlet pipe 610 is the bypass unit 400 . The reducing agent injection unit 500 is mixed with the injected reducing agent, and then moves to the body unit 300 through the opening 304 and is discharged to the main discharge pipe 630 through the catalyst 350 .

On the other hand, when the main valve 730 is closed and the bypass valve 740 is opened, the exhaust gas flowing into the bypass unit 400 through the main inlet pipe 610 goes directly to the bypass outlet pipe 640 without going through a catalyst. is emitted At this time, the reducing agent injection unit 500 does not spray the reducing agent.

In addition, in the second embodiment of the present invention, the bypass unit 400 is installed inside the body unit 300 . The inside of the main body 310 is maintained at the active temperature of the catalyst, for example, a temperature within the range of 200 degrees Celsius to 500 degrees Celsius for a smooth reduction reaction. However, in the second embodiment of the present invention, since the bypass unit 400 is installed inside the body unit 300 , the bypass unit 400 may also be maintained close to the internal temperature of the reactor body 300 . That is, since the reducing agent injected from the reducing agent injection unit 500 is mixed with the exhaust gas in the bypass unit 400 having an appropriate temperature for the reduction reaction, the vaporization of the reducing agent becomes more active so that it can be mixed with higher efficiency as well as the reduction reaction Efficiency can also be improved.

By this configuration, the selective catalytic reduction reactor 102 according to the second embodiment of the present invention also increases space utilization and minimizes the space required for installation, thereby improving the ease of installation and maintenance.

In addition, according to the second embodiment of the present invention, the exhaust gas introduced into one end of the bypass unit 400 through the main inlet pipe 610 moves toward the other end of the bypass unit 400 and then opens It is introduced into the interior of the body portion 300 through 304 . Then, the exhaust gas is discharged through the main discharge pipe 630 through the catalyst after the movement direction is changed in the body portion 300 . In this way, as the movement direction of the exhaust gas is switched, the exhaust gas and the reducing agent can be mixed more effectively. Accordingly, a mixer for mixing the exhaust gas and the reducing agent may be omitted.

In addition, according to the second embodiment of the present invention, the reducing agent injection unit 500 and the bypass unit 400 needlessly in order to secure a residence time for the reducing agent injected from the reducing agent injection unit 500 to be mixed with the exhaust gas. There is no need to lengthen the exhaust flow path between the reducing agent injection unit 500, and it does not matter if the reducing agent injection unit 500 is installed at a position close to the body unit 300 and the bypass unit 400 of the selective catalytic reduction reactor 102. The degree of freedom of installation of 500 is increased. Therefore, the position of the reducing agent injection unit 500 can be freely set according to the size and shape of the space in which the selective catalytic reduction reactor 102 is to be installed.

In addition, according to the second embodiment of the present invention, the selective catalytic reduction reactor 102 can suppress unnecessary waste of overall thermal energy consumed to vaporize the reducing agent and reduce nitrogen oxides.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains can understand that the present invention may be embodied in other specific forms without changing the technical spirit or essential features thereof. will be.

Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all respects, and the scope of the present invention is indicated by the following claims, the meaning and scope of the claims, and All changes or modifications derived from the equivalent concept should be construed as being included in the scope of the present invention.

101, 102: selective catalytic reduction reactor
300: body part
304: opening
309: body outlet
400: bypass unit
401: inlet
409: bypass outlet
430: guide vanes
500: reducing agent injection unit
610: main inlet pipe
630: main discharge pipe
640: bypass discharge pipe
730: main valve
740: bypass valve

Claims (6)

In the selective catalytic reduction reactor for reducing nitrogen oxides contained in exhaust gas,
a body part connected to the main discharge pipe at one end and having an opening on the other side;
a bypass part integrally coupled to the other side of the body part having the opening, communicating with the inside of the body part through the opening, connected to the main inlet pipe at one end, and connected to the bypass outlet pipe at the other end; and
Catalyst disposed between the opening and the main discharge pipe in the body part
A selective catalytic reduction reactor comprising a. According to claim 1,
and a guide vane installed inside the bypass unit adjacent to the opening of the main body to diffuse and move the exhaust gas so that the exhaust gas flowing into the interior of the main body through the opening evenly contacts the catalyst. Selective catalytic reduction reactor, characterized in that. In the selective catalytic reduction reactor for reducing nitrogen oxides contained in exhaust gas,
a body part connected to the main exhaust pipe through which exhaust gas is discharged from the first area;
It is installed inside the main body, and one end is connected to the main inlet pipe through which exhaust gas is introduced through the second area of the main body, the other end is opened inside the main body, and the other side is the third area of the main body. a bypass unit connected to the bypass discharge pipe passing through; and
Catalyst disposed between the opening of the bypass part and the main discharge pipe in the body part
A selective catalytic reduction reactor comprising a. 4. The method of claim 1 or 3,
Further comprising a reducing agent injection unit installed in the main inlet pipe,
Selective catalytic reduction reactor, characterized in that the reducing agent injected from the reducing agent injection part is mixed with the exhaust gas inside the bypass part and then introduced into the body part through the opening. 4. The method of claim 1 or 3,
A selective catalytic reduction reactor, characterized in that a main valve is formed in the main discharge pipe, and a bypass valve is formed in the bypass discharge pipe. 6. The method of claim 5,
When the main valve is opened and the bypass valve is closed, the exhaust gas introduced into the bypass unit through the main inlet pipe moves to the main body through the opening and is discharged to the main discharge pipe through the catalyst,
When the main valve is closed and the bypass valve is opened, the exhaust gas introduced into the bypass unit through the main inlet pipe is discharged to the bypass discharge pipe.

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