KR102402331B1 - Reaction 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 has a hollow cylindrical shape with one end of a hemispherical shape or a curved plate convex to the outside. a reactor body having a reactor body, a plurality of catalyst modules loaded inside the reactor body, a discharge pipe connected to the other side of the reactor body, and a space between the plurality of catalyst modules and the inner wall surface of the reactor body inserted into the other side of the reactor body A plurality of inlet pipes passing through the space and having one end opposite to the inner surface of one end of the reactor body, and an exhaust passage that surrounds the discharge pipe and is connected to the other end of the plurality of inlet pipes and through which the exhaust gas moves and an annular chamber having a connector for being

Description

Selective catalytic reduction reactor

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, or from thermal power plants or factories.

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. In the selective catalytic reduction system, the exhaust gas and the reducing agent pass together through a reactor in which the catalyst is installed, and the nitrogen oxides and the reducing agent contained in the exhaust gas are reacted to reduce the nitrogen and water vapor.

When such a selective catalytic reduction system is used for a ship, 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 simplification of the selective catalytic reduction system used in the ship is required.

As shown in Figure 1, the conventional selective reduction system used in ships is an exhaust passage 61 through which the exhaust gas discharged from the engine moves, and injecting a reducing agent to the exhaust gas moving along the exhaust passage 61 The reducing agent injection unit 41 and the decomposition chamber or evaporator 40 installed on the exhaust flow path 61 to decompose or vaporize the reducing agent injected through the reducing agent injection unit 41, and the reducing agent with the exhaust gas A mixer (mixer) 45 for mixing, and a catalyst 35 for the selective catalytic reduction reaction includes a reactor 30 provided therein.

However, when urea is used as a reducing agent, since urea injected through the reducing agent injection unit 41 must undergo a decomposition process, it is thermally decomposed or hydrolyzed before reaching the reactor 30 in which the catalyst 35 is installed from the point where the urea is injected. A residence time is required for And in order to secure such a residence time, the exhaust flow path 61 is required to have a minimum length (L). In this way, the long length (L) of the exhaust passage greatly reduces the ease of installation according to the spatial limitation when installing the selective catalytic reduction system on a ship.

In addition, since the conventional selective catalytic reduction system uses a separate decomposition chamber or vaporizer 50, the size of the overall space occupied by the selective catalytic reduction system is increased. And since the exhaust passage 61 is connected to the front and rear ends of the reactor 30 in only one direction, the installation of the reactor 30 is limited in space.

As described above, in order to maximize the efficiency of the selective catalytic reduction system in a limited space such as a ship, the overall structure becomes complicated and the optimal installation is not easy. 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 increasing space utilization.

According to an embodiment of the present invention, the selective catalytic reduction reactor includes a reactor body having a hollow cylindrical shape having one end of a hemispherical shape or an externally convex curved plate, a plurality of catalyst modules loaded inside the reactor body, and the reactor body a plurality of discharge pipes connected to the other side of the reactor body and inserted into the other side of the reactor body, passing through the space between the plurality of catalyst modules and the inner wall surface of the reactor body, and having one end opposite to the inner surface of one end of the reactor body An inlet pipe and an annular chamber surrounding the outlet pipe and connected to the other ends of the plurality of inlet pipes and having a connector for connecting to an exhaust passage through which exhaust gas moves.

The plurality of catalyst modules may be formed in a hexahedron. And it may be loaded in a direction crossing the longitudinal direction of the inlet pipe to form a catalyst layer.

In addition, the plurality of catalyst modules may form a plurality of the catalyst layers. In addition, the plurality of catalyst layers may be arranged to be spaced apart from each other based on a direction in which the exhaust gas moves in the reactor body.

The plurality of inlet pipes may be radially disposed around the discharge pipe.

The selective catalytic reduction reactor may further include an annular support for supporting one end of the plurality of inlet pipes in the interior of the reactor body.

In addition, a plurality of connectors of the annular chamber may be provided.

The connector of the annular chamber may be formed in a direction parallel to the longitudinal direction of the inlet pipe.

In addition, the connector of the annular chamber may be formed in a direction crossing the longitudinal direction of the inlet pipe.

The selective catalytic reduction reactor may further include one or more reducing agent injection units coupled to the plurality of inlet pipes or the annular chamber to inject a reducing agent.

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

In addition, according to an embodiment of the present invention, the selective catalytic reduction reactor can be freely installed in various directions and angles.

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

1 is a block diagram showing a conventional selective catalytic reduction system for reducing nitrogen oxides contained in exhaust gas.
2 is a perspective view showing a selective catalytic reduction reactor according to a first embodiment of the present invention.
3 is a longitudinal cross-sectional view of the selective catalytic reduction reactor of FIG. 1 .
4 is a cross-sectional view of the selective catalytic reduction reactor of FIG. 1 .
5 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, the 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. And the same reference numerals are used to denote 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. 2 to 4 .

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 .

2 to 4, the selective catalytic reduction reactor 101 according to the first embodiment of the present invention has a reactor body 300, a plurality of catalyst modules 350, an exhaust pipe 520, a plurality of inlets tube 510 , and an annular chamber 550 .

In addition, the selective catalytic reduction reactor 101 according to the first embodiment of the present invention may further include an annular support 580 and a reducing agent injection unit 410 .

The reactor body 300 is basically formed in a cylindrical shape. And one end 308 corresponding to the bottom of the cylindrical shape is formed in a hemispherical shape protruding to the outside or a curved plate convex to the outside. That is, the reactor body 300 has a hemispherical shape with one end 308 protruding to the outside or a hollow cylindrical shape formed of a curved plate convex to the outside.

The plurality of catalyst modules 350 are loaded inside the reactor body 300 . In addition, the plurality of catalyst modules 350 are loaded in a direction crossing the movement direction of the exhaust gas in the reactor body 300 or in a direction crossing the longitudinal direction of the inlet pipe 510 to be described later to form a catalyst layer.

In addition, the plurality of catalyst modules 350 may form a plurality of catalyst layers in the reactor body 300 . The plurality of catalyst layers are arranged to be spaced apart from each other in the direction in which the exhaust gas moves in the reactor body 300 .

In addition, the plurality of catalyst modules 350 each includes a catalyst for the selective catalytic reduction reaction. In addition, the plurality of catalyst modules 350 may be formed in a hexahedron. For example, the plurality of catalyst modules 350 may be a rectangular parallelepiped or a cube. When the catalyst module 350 is formed in a cuboid or cube as described above, it is easy to load the catalyst module 350 as well as easy to replace and transport the catalyst module 350, and the catalyst contained in the catalyst module 350 is efficiency can be maximized.

However, when a cuboid or cube-shaped catalyst module 350 is loaded inside the cylindrical reactor body 300, a gap is inevitably generated between the inner surface of the reactor body 300 and the plurality of catalyst modules 350. .

In addition, the catalyst included in the plurality of catalyst modules 350 may be made of various materials known to those skilled in the art, such as zeolite, vanadium, and platinum. As an example, the catalyst 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 can stably reduce nitrogen oxides without being poisoned. If the catalyst reacts outside the active temperature range, the catalyst 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 may include at least one of ammonium sulfate ((NH ₄ ) ₂ SO ₄ ) and ammonium bisulfate (NH ₄ HSO ₄ ). These catalyst poisoning substances are adsorbed to the catalyst to reduce the activity of the catalyst. Since the catalyst poisoning material decomposes at a relatively high temperature, that is, at a temperature within the range of 350 degrees Celsius to 450 degrees Celsius, the catalyst in the reactor may be heated to regenerate the poisoned catalyst.

In addition, ammonia (NH ₃ ) is used as a reducing agent that directly reacts with nitrogen oxides in the catalyst, which is a reducing agent precursor urea (urea, CO(NH ₂ ) ₂ ) It may be supplied in the form of an aqueous solution. Since ammonia itself is a contaminant, it is not easy to store and transport, so it is common to use a stable aqueous urea 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, a reducing agent that reacts with nitrogen oxides.

The discharge pipe 520 is connected to the other side of the reactor body 300 . The discharge pipe 520 discharges the exhaust gas that has passed through the plurality of catalyst modules 350 after being introduced into the reactor body 300 to the outside of the reactor body 300 .

The plurality of inlet pipes 510 are inserted into the other side of the reactor body 300 and penetrate the space between the plurality of catalyst modules 350 and the inner wall surface of the reactor body 300 , and the one end 308 of the reactor body 300 . ) and has one end opposite to the inner surface. That is, in the first embodiment of the present invention, a gap inevitably generated between the inner wall surface of the cylindrical reactor body 300 and the plurality of catalyst modules 350 that is a cuboid or cube is formed by a plurality of inlet pipes 510. Use it as a passing space. And the other ends of the plurality of inlet pipes 510 are connected to the annular chamber 550 to be described later from the outside of the reactor body 300 .

In addition, the plurality of inlet pipes 510 may be radially disposed with respect to the discharge pipe 520 . In this way, as the plurality of inlet pipes 510 are radially disposed, the exhaust gas and the reducing agent may be introduced while being evenly distributed in the reactor body 300 .

The annular support 580 supports one end of the plurality of inlet pipes 510 inside the reactor body 300 . That is, the annular support 580 includes one end 308 of the reactor body 300 formed of a hemispherical shape protruding to the outside or an outwardly convex curved plate and a plurality of catalyst modules 350 loaded inside the reactor body 300 . can be formed in between.

The annular chamber 550 surrounds the discharge pipe 520 and is connected to the other end of the plurality of inlet pipes 510 . And the annular chamber 550 has a connector 557 for being connected to the exhaust passage through which the exhaust gas moves.

With this configuration, the exhaust gas introduced into the inlet 557 of the annular chamber 550 is uniformly dispersed in the annular chamber 550 and then moves into the reactor body 300 through the plurality of inlet pipes 510 . will do That is, the annular chamber 550 serves to distribute the exhaust gas moving along the exhaust flow path to the plurality of inlet pipes 510 .

The reducing agent spraying unit 410 may be coupled to the plurality of inlet pipes 510 or the annular chamber 550 to spray the reducing agent. In addition, in the first embodiment of the present invention, one or more reducing agent injection unit 410 may be provided. When the reducing agent is sprayed into the plurality of reducing agent spraying units 410, the sprayed reducing agent can be easily atomized, and the reducing agent distribution area is increased to be effective in decomposing the reducing agent.

When a plurality of reducing agent injection unit 410 is used, the reducing agent injection unit 410 may be coupled to each of the plurality of inflow pipes 510 . In addition, a plurality of reducing agent injection unit 410 may be radially coupled to the annular chamber 550 .

When the reducing agent injection unit 410 injects the reducing agent to the annular chamber 550, the annular chamber 550 serves as a decomposition chamber or vaporizer for decomposing or vaporizing the reducing agent together with the role of distributing the exhaust gas. Also, it is possible to effectively mix the exhaust gas and the reducing agent.

In the first embodiment of the present invention, since the reducing agent injection unit 410 injects the urea aqueous solution as a reducing agent, the injected urea must first undergo a process of decomposition into ammonia in order to react with nitrogen oxides in the catalyst.

However, according to the first embodiment of the present invention, since the plurality of inlet pipes 510 extend long from the inside of the reactor body 300 to a position opposite to the one end 308, the catalyst from the point where the reducing agent urea is sprayed. It is possible to effectively secure a long distance to reach the module 350 . That is, it is possible to stably secure a residence time for the reducing agent injected from the reducing agent injection unit 410 to be thermally decomposed or hydrolyzed.

In addition, since there is no need to form the length of the inlet pipe 510 or the exhaust passage from the outside of the reactor body 300 to be long, it is possible to overcome the spatial limitation when installing the selective catalytic reduction system on a ship, thereby greatly improving the ease of installation. .

In addition, the inside of the reactor body 300 is maintained at the active temperature of the catalyst for a smooth reduction reaction, for example, a temperature within the range of 200 degrees Celsius to 500 degrees Celsius. However, in the first embodiment of the present invention, since the plurality of inlet pipes 510 pass through the inside of the reactor body 300 , the plurality of inlet pipes 510 are also maintained close to the internal temperature of the reactor body 300 . can That is, the reducing agent injected by the reducing agent injection unit 410 through the internal temperature of the reactor body 300 without the need to supply separate thermal energy to decompose the reducing agent injected into the plurality of inlet pipes 510 or the annular chamber 550 . can be decomposed or vaporized.

As such, according to the first embodiment of the present invention, there is no need to separately supply thermal energy for decomposing the reducing agent and thermal energy for maintaining the internal temperature of the reactor body 300 in the active temperature range of the catalyst reactor body 300 It is possible to decompose or vaporize the reducing agent only by maintaining the internal temperature of the

In addition, the exhaust gas and the reducing agent introduced into the reactor body 300 through the inlet pipe 510 collide with one end 308 of the reactor body 300 formed in a hemispherical shape protruding to the outside or a convex curved plate to the outside. After the movement direction is changed, it passes through the plurality of catalyst modules 350 .

As such, it is possible to further secure a residence time for urea to be decomposed into ammonia in the process where the exhaust gas and the reducing agent introduced into the inlet pipe 510 collide with one end 308 of the reactor body 300 and the direction is changed. In addition, the exhaust gas and the reducing agent can be effectively mixed.

In addition, while the exhaust gas and the reducing agent collide with the one end 308 of the reactor body 300 and the direction is changed, a swirling flow may be generated according to the shape of the one end 308 of the reactor body 300 . In this case, the exhaust gas and the reducing agent can be mixed more effectively. In addition, when the swirl flow is formed, the exhaust gas and the reducing agent are mixed and then evenly distributed and delivered to the plurality of catalyst modules 350 .

By such a configuration, the selective catalytic reduction reactor 101 according to the first embodiment of the present invention increases space utilization and minimizes the space required for installation, thereby improving the ease of installation and maintenance.

In addition, according to the first embodiment of the present invention, the selective catalytic reduction reactor 101 decomposes or vaporizes the reducing agent and can suppress unnecessary waste of overall thermal energy consumed to reduce nitrogen oxides.

In particular, according to the first embodiment of the present invention, there is no need to separately provide a decomposition chamber or vaporizer for decomposing and vaporizing the reducing agent.

In addition, according to the first embodiment of the present invention, there is no need to unnecessarily lengthen the exhaust flow path in order to secure a residence time for the injected reducing agent to be thermally decomposed or hydrolyzed.

In addition, according to the first embodiment of the present invention, the mixer for mixing the exhaust gas and the reducing agent may be omitted.

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

5, in the selective catalytic reduction reactor 102 according to the second embodiment of the present invention, a plurality of connectors 557 of the annular chamber 550 may be provided.

In addition, the connector 557 of the annular chamber 550 may be formed in a direction parallel to the longitudinal direction of the inlet pipe 510 .

In addition, the connector 557 of the annular chamber 550 may be formed in a direction crossing the longitudinal direction of the inlet pipe 510 .

By this configuration, according to the second embodiment of the present invention, a plurality of connectors 557 are formed in various angles and directions in the annular chamber 550, and the direction and angle in which the selective catalytic reduction reactor 102 is installed. By selecting and using a connector 557 that is easy to connect with the exhaust flow path through which the exhaust gas moves from among the plurality of connector 557 according to the It can be installed freely. That is, by connecting the front and rear ends of the selective catalytic reduction reactor 102 with the exhaust flow path in only one direction, it is possible to solve the spatial limitation generated during installation.

Although the 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 characteristics 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: reactor body
308: one end of the reactor body
350: catalyst module
410: reducing agent injection unit
510: inlet pipe
520: discharge pipe
550: annular chamber
557: connector
580: annular support

Claims (9)

A reactor body having a hollow cylindrical shape having one end of a hemispherical shape or an externally convex curved plate;
a plurality of catalyst modules loaded inside the reactor body;
a discharge pipe connected to the other side of the reactor body;
a plurality of inlet pipes inserted into the other side of the reactor body through a space between the plurality of catalyst modules and an inner wall surface of the reactor body and having one end opposite to an inner surface of one end of the reactor body; and
An annular chamber surrounding the discharge pipe and connected to the other ends of the plurality of inlet pipes and having a connector for connecting to the exhaust passage through which the exhaust gas moves
including,
The plurality of catalyst modules are formed in a cube or a rectangular parallelepiped,
The plurality of inlet pipes are disposed in a gap between the inner surface of the reactor body and the plurality of catalyst modules generated while loading the plurality of catalyst modules, which are cubes or cuboids, inside the reactor body having a cylindrical shape. . According to claim 1,
Selective catalytic reduction reactor, characterized in that it is loaded in a direction crossing the longitudinal direction of the inlet pipe to form a catalyst layer. 3. The method of claim 2,
The plurality of catalyst modules form a plurality of the catalyst layers,
The plurality of catalyst layers are selective catalytic reduction reactor, characterized in that arranged spaced apart based on the direction in which the exhaust gas moves in the reactor body. According to claim 1,
Selective catalytic reduction reactor, characterized in that the plurality of inlet pipes are radially arranged around the discharge pipe. According to claim 1,
Selective catalytic reduction reactor, characterized in that it further comprises an annular support for supporting one end of the plurality of inlet pipes in the interior of the reactor body. According to claim 1,
Selective catalytic reduction reactor, characterized in that the plurality of connectors of the annular chamber are provided. According to claim 1,
The connector of the annular chamber is a selective catalytic reduction reactor, characterized in that formed in a direction parallel to the longitudinal direction of the inlet pipe. According to claim 1,
The connector of the annular chamber is a selective catalytic reduction reactor, characterized in that formed in a direction crossing the longitudinal direction of the inlet pipe. 9. The method according to any one of claims 1 to 8,
Selective catalytic reduction reactor, characterized in that it further comprises one or more reducing agent injection unit coupled to the plurality of inlet pipe or the annular chamber to inject a reducing agent.

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