KR20170075964A - Selective catalytic reuction system - Google Patents

Abstract

The present invention relates to a selective catalytic reduction system, and a selective catalytic reduction system according to an embodiment of the present invention includes an exhaust flow passage through which exhaust gas containing nitrogen oxides (NOx) discharged during a power generation process moves, A recirculation flow path branched from the exhaust flow path behind the reactor and joined to the branch flow path in front of the reactor; a heating device installed on the recirculation flow path; And a regeneration auxiliary flow path branched from the recirculation flow path between the confluence point of the exhaust flow path and the heating device and joining the exhaust flow path between the exhaust flow path and the branch point of the recirculation flow path and the rear end of the reactor.

Description

{SELECTIVE CATALYTIC REUCTION SYSTEM}

The present invention relates to a selective catalytic reduction system for reducing nitrogen oxides contained in an exhaust gas using a selective catalytic reduction reaction.

Generally, the power unit used in ships and the like is composed of a diesel engine for generating power, a turbocharger for supplying air to the diesel engine, and a selective catalytic reduction for reducing the nitrogen oxide contained in the exhaust gas from the diesel engine selective catalytic reduction (SCR) systems, and the like.

The selective catalytic reduction system reacts the nitrogen oxides contained in the exhaust gas with the reducing agent while passing the exhaust gas and the reducing agent together in the reactor equipped with the catalyst, thereby reducing the nitrogen and the water vapor.

When this selective catalytic reduction system is used in ships, its performance and operation are required so that the emission amount of NOx emitted from the marine diesel engine can satisfy the IMO Tier III .

In addition, the selective catalytic reduction system mainly utilizes a high-temperature active catalyst having an active temperature within the range of 250 ° C. to 350 ° C. in consideration of economical efficiency and radioactivity regulation. Here, the activation temperature refers to a temperature at which the catalyst can be stably reduced without being poisoned.

However, when the catalyst reacts outside the activation temperature range, the activity of the catalyst is continuously deteriorated as the catalyst is poisoned. Particularly, when exhaust gas having a relatively low temperature of less than 250 ° C. is introduced into a reactor equipped with a high-temperature active catalyst, sulfur oxide (SOx) of exhaust gas reacts with ammonia (NH ₄ ) do. Catalyst poisoning material may comprise one or more of ammonium sulfate _{(Ammonium sulfate, (NH4) 2} SO 4) and ammonium bisulfite _{(Ammonium bisulfate, NH 4 HSO 4} ).

Such a catalyst poisoning material is adsorbed on the catalyst to lower the activity of the catalyst. Therefore, in order to increase the efficiency of the catalyst and minimize the loss due to maintenance, it is required to keep the temperature of the catalyst within the active temperature range.

However, in the case of a low speed diesel engine for ships, since the emission amount of the exhaust gas changes according to the load change of the diesel engine and the climate environment in which the ship is operating also affects the selective catalytic reduction reaction, .

An embodiment of the present invention provides a selective catalytic reduction system capable of effectively regenerating a poisoned catalyst.

According to an embodiment of the present invention, a selective catalytic reduction system includes an exhaust flow path through which exhaust gas containing nitrogen oxides (NOx) discharged during a power generation process moves, a reactor provided on the exhaust flow path, A recirculation flow path branched from the exhaust flow path behind the reactor and joined to the branch flow path in front of the reactor, a heating device installed on the recirculation flow path, and a circulation path between the recirculation flow path and the exhaust flow path, And a regeneration auxiliary flow path branching from the recirculation flow path and joining to the exhaust flow path between a branch point of the exhaust flow path and the recirculation flow path and a rear end of the reactor.

The selective catalytic reduction system may include a post-treatment mode in which the exhaust gas discharged during the power generation process moves through the reactor along the exhaust passage, and a closed loop including the heating device, And a catalyst regeneration mode for regenerating the catalyst.

The selective catalytic reduction system includes a main valve disposed in the exhaust passage in front of a confluence point of the exhaust passage and the recirculation passage, an auxiliary valve provided in the exhaust passage behind the branch point of the exhaust passage and the recirculation passage, A recirculation valve provided on the recirculation passage between a recirculation passage and a branch point of the recycling auxiliary passage and a junction point between the recirculation passage and the exhaust passage; and a regeneration assisting valve provided on the regeneration assistance passage.

In the post-treatment mode, the main valve, the auxiliary valve, and the recirculation valve may be open and the regeneration auxiliary valve closed.

Wherein the catalyst regeneration mode is a mode in which the main valve, the auxiliary valve, and the regeneration auxiliary valve are closed and the recirculation valve is opened, and the main valve, the auxiliary valve, and the recirculation valve are closed, The regeneration assistant valve may be opened and the regeneration valve may be closed, and the recycle valve and the regeneration assisting valve may be opened.

The selective catalytic reduction system may further include a bypass flow path branched from the exhaust flow path in front of the main valve and joined to the exhaust flow path behind the auxiliary valve, and a bypass valve provided on the bypass flow path .

The bypass valve may be closed in the post-treatment mode and open in the catalyst regeneration mode.

The selective catalytic reduction system may further include an outside air supply unit connected to the recirculation flow path to supply oxygen required for the heating apparatus.

When the outside air supply unit is activated, the auxiliary valve may be at least partially opened.

The selective catalytic reduction system may further include a decomposition chamber provided on the branch passage and a reducing agent supply unit for supplying a reducing agent or a reducing agent precursor to the decomposition chamber.

The selective catalytic reduction system may further include a blower installed on the branch passage.

In the post-treatment mode, the temperature of the decomposition chamber may be lower than the reducing agent production temperature or the catalyst may be operated in the catalyst regeneration mode.

According to an embodiment of the present invention, the selective catalytic reduction system can effectively regenerate the poisoned catalyst.

1 is a block diagram of a selective catalytic reduction system according to an embodiment of the present invention.
FIGS. 2 to 4 are block diagrams showing an operation state of the selective catalytic reduction system of FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

The drawings are schematic and illustrate that they are not drawn to scale. The relative dimensions and ratios of the parts in the figures are exaggerated or reduced in size for clarity and convenience in the figures, and any dimensions are merely illustrative and not restrictive. And to the same structure, element or component appearing in more than one drawing, the same reference numerals are used to denote similar features.

The embodiments of the present invention specifically illustrate ideal embodiments of the present invention. As a result, various variations of the illustration are expected. Thus, the embodiment is not limited to any particular form of the depicted area, but includes modifications of the form, for example, by manufacture.

Hereinafter, a selective catalytic reduction (SCR) system 101 according to an embodiment of the present invention will be described with reference to FIG.

The selective catalytic reduction reaction system 101 according to an embodiment of the present invention reduces nitrogen oxides (NOx) contained in the exhaust gas discharged from the power unit. Here, the power unit includes a diesel engine 200. That is, the power unit may include a diesel engine 200 used as a main power source for supplying driving force to a ship or a vehicle. For example, the diesel engine 200 may be a two-stroke low-speed diesel engine for a marine vessel.

However, the embodiment of the present invention is not limited thereto. The power unit may be an internal combustion engine for a plant or an automotive engine. That is, as the diesel engine 200, various types of engines known to those skilled in the art can be used.

In addition, the power unit may include a supercharger 250. The supercharger 250 is connected to the exhaust port of the diesel engine 200 to rotate the turbine with the pressure of the exhaust gas of the diesel engine 200 to supply new external air to the diesel engine 200. Thus, the efficiency of the diesel engine 200 equipped with the turbocharger 250 is improved. However, the turbocharger 250 may be omitted as necessary, and may be installed at various positions as known to those skilled in the art without being limited to the position shown in FIG.

In one embodiment of the present invention, the exhaust gas discharged from the diesel engine 200 has a temperature within a range of 250 degrees Celsius to 500 degrees Celsius, and the temperature of the exhaust gas can be lowered through the supercharger 250. For example, the exhaust gas passing through the turbocharger 250 can be lowered to a temperature of not less than 150 degrees Celsius and less than 250 degrees Celsius.

1, a selective catalytic reduction (SCR) system 101 according to an embodiment of the present invention includes an exhaust passage 610, a reactor 300, a recirculation passage 680, (400), and a reproduction auxiliary flow path (690).

The selective catalytic reduction system 101 according to an embodiment of the present invention includes a blower 450, a decomposition chamber 500, a reducing agent supply unit 550, a reducing agent injection unit 570, a bypass flow channel 620, And may further include an outside air supply unit 800.

The selective catalytic reduction system 101 according to an embodiment of the present invention includes a main valve 710, a bypass valve 720, an auxiliary valve 730, a recirculation valve 780, and a regeneration auxiliary valve 790, As shown in FIG.

The exhaust passage 610 moves and discharges the exhaust gas containing nitrogen oxides (NOx) discharged during the power generation process. Specifically, the exhaust passage 610 is connected to the exhaust port of the diesel engine 200 to exhaust exhaust gas of the engine 200. When the turbocharger 250 is installed, the exhaust passage 610 can sequentially connect the diesel engine 200, the turbocharger 250, and the reactor 300, which will be described later. That is, the exhaust gas of the diesel engine 200 moves along the exhaust passage 610. Thus, the exhaust passage 610 supplies the exhaust gas of the diesel engine 200 to the reactor 300.

The reactor 300 is installed on the exhaust passage 610. The reactor 300 includes a catalyst 350 for reducing nitrogen oxides (NOx) contained in the exhaust gas discharged during the power generation process. The catalyst 350 promotes the reaction of the reducing agent with the nitrogen oxides (NOx) contained in the exhaust gas to reduce the nitrogen oxides (NOx) to nitrogen and water vapor.

Also, in an embodiment of the present invention, the catalyst 350 installed inside the reactor 300 may be arranged in a multi-layer structure based on the moving direction of the exhaust gas. That is, the catalyst 350 may be provided in the form of a plurality of catalyst modules, and the plurality of catalyst modules may be arranged along the moving direction of the exhaust gas.

Catalyst 350 may be made from a variety of materials known to those skilled in the art, such as zeolite, vanadium, and platinum. In one example, catalyst 350 may have an active temperature in the range of 250 degrees Celsius to 350 degrees Celsius. Here, the activation temperature refers to a temperature at which the catalyst 350 can be stably reduced without being poisoned. When the catalyst 350 reacts in an environment outside the activation temperature range, the catalyst 350 is poisoned and the efficiency is lowered.

For example, occurs the reduction reaction for reducing nitrogen oxide-containing exhaust gas at a relatively low temperature of less than ° C more than 250 ° C, 150, of the exhaust gas sulfur oxides (SOx) and ammonia (NH ₃₎ the reaction Thereby forming a catalyst poisoning substance.

Specifically, the poisoning substance that poisons the catalyst 350 may include at least one of ammonium sulfate (NH ₄ ) ₂ SO ₄ and ammonium hydrogen sulfite (NH ₄ HSO ₄ ). Such a catalyst poisoning substance is adsorbed on the catalyst 350 to lower the activity of the catalyst 350. Since the catalyst poisonous substance 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 300 can be heated to regenerate the poisoned catalyst 350.

Ammonia (NH ₃ ) or urea (urea, CO (NH ₂ ) ₂ ) may be used as the reducing agent. When urea is used as the reducing agent, ammonia (NH ₃ ) and isocyanic acid (HNCO) are produced by hydrolysis or pyrolysis of urea (urea, CO (NH ₂ ) ₂ ). And isocyanate (HNCO) decomposes again into ammonia (NH ₃ ) and carbon dioxide (CO ₂ ). That is, it decomposes urea to finally produce ammonia. And ammonia (NH ₃ ) acts as a final reducing agent that reacts directly with nitrogen oxides. Urea (urea, CO (NH ₂ ) ₂ ) and isocyanic acid (HNCO) correspond to the reducing agent precursor.

In addition, the housing of the reactor 300 may be made of stainless steel having excellent heat resistance, for example.

The recirculation flow path 680 branches off from the exhaust flow path 610 behind the reactor 300 and joins the exhaust flow path 610 in front of the reactor 300. That is, a part of the exhaust gas passing through the reactor 300 can be recirculated to the front of the reactor through the recycle passage 680. A part of the exhaust gas recirculated through the recirculation flow path 680 may be used to decompose and produce the reducing agent in the decomposition chamber 500 to be described later and may be used for regeneration of the catalyst 350 installed in the reactor 300.

In the present specification, the front means the upstream side based on the flow of the exhaust gas and the rear means the downstream side.

The heating device 400 is installed on the recirculation flow path 680. When the heating apparatus 400 is operated, a part of the fluid flowing through the recirculation flow path 680, that is, a part of the exhaust gas passing through the reactor 300, is heated to raise the temperature. For example, the heating device 400 may be an oil burner or a plasma burner. That is, in one embodiment of the present invention, oxygen may be required to operate the heating apparatus 400.

In one embodiment of the present invention, the thermal energy supplied by the heating device 400 may be used to decompose and produce the reducing agent, or may be used to regenerate the catalyst 350 installed in the reactor 300. In this way, when regenerating the catalyst 350, a closed loop including a part of the exhaust flow path 610 and the recirculation flow path 680 is formed, and the heating device 400 is disposed in the closed loop .

The blower 450 can be installed on the recirculation flow path 680 in the same manner as the heating apparatus 400. The blower 450 can control the flow rate and the flow rate of the fluid moving along the recirculation flow path 680.

The outside air supply part 800 may be connected to the recirculation flow path 680 to supply the outside air to the heating device 400. That is, the outside air supply unit 800 can supply oxygen necessary for operating the heating apparatus 400. At this time, the outside air supply unit 800 supplies only the air to which the heating device 400 supplies oxygen necessary for burning the fuel. Particularly, in the catalyst regeneration process, the heating device 400 is operated in the place where the closed loop is formed. Therefore, if the outside air supply part 800 is not provided, the heating device 400 may be continuously operated and the combustion air may be insufficient.

The outside air supply unit 800 may include an outside air supply passage for injecting outside air, an outside air supply valve for opening and closing the outside air supply passage, or an outside air supply pump, though not shown.

As described above, in an embodiment of the present invention, when the burner requiring combustion air is used as the heating device 400, the heating device 400 can receive oxygen from the outside air supply part 800, 400 can be operated effectively.

The decomposition chamber 500 is installed on the recirculation passage 680. The decomposition chamber 500 generates ammonia (NH ₃ ) which is used as a reducing agent to reduce nitrogen oxide (NOx) by decomposing the urea (CO (NH ₂ ) ₂ ) as a reducing agent precursor.

If specifically, the temperature in the decomposition chamber 500 is maintained within Celsius 300 degrees to degrees Celsius to 500 degrees, urea (urea, CO (NH _{2) 2)} is as easily hydrolyzed ammonia (NH ₃₎ and isocyanate ( Isocyanic acid, HNCO). And isocyanate (HNCO) is decomposed again into ammonia (NH ₃ ) and carbon dioxide (CO ₂ ). That is, when urea is decomposed, ammonia may finally be generated.

The reducing agent spraying unit 570 injects ammonia (NH ₃ ) generated in the decomposition chamber 500 into the exhaust gas to be introduced into the reactor 300. Ammonia injected through the reducing agent injecting section 570 is mixed with the exhaust gas to reduce the nitrogen oxide contained in the exhaust gas through the catalyst 350 of the reactor 300. For example, the reducing agent spraying section 570 may be installed at a junction point between the recirculation passage 680 and the exhaust passage 610, that is, in the exhaust passage 610 in front of the reactor 300. Also, the reducing agent spraying unit 570 may be installed at the front end of the reactor 300.

The reducing agent supply unit 550 supplies urea, which is a reducing agent precursor, to the decomposition chamber 500. The reducing agent supply unit 550 can supply an appropriate amount of urea to the decomposition chamber 500 in consideration of the amount of reducing agent that varies depending on the load of the diesel engine 200. [

The reducing agent supply unit 550 may include various configurations known to those skilled in the art such as a storage tank, compressed air supply apparatus for spraying, and the like.

The regeneration auxiliary flow path 690 is branched from the junction point between the recirculation flow path 680 and the exhaust flow path 610 and the recirculation flow path 680 between the heating device 400 and branches the exhaust flow path 610 and the recirculation flow path 680 And can join the exhaust flow path 610 between the point and the rear end of the reactor 300. The regeneration auxiliary flow path 690 can be utilized together with the recirculation flow path 680 in the process of regenerating the catalyst 350. [

The main valve 710 may be installed in the exhaust passage 610 in front of the confluence point of the exhaust passage 610 and the recirculation passage 680. The auxiliary valve 730 may be installed in the exhaust passage 610 behind the branch point of the recirculation passage 680. That is, the main valve 710 and the auxiliary valve 730 are installed at the front and rear of the reactor 300 to open and close the exhaust passage 610, respectively.

The recirculation valve 780 may be installed on the recirculation flow path 680 between the recirculation flow path 680 and the regeneration assist flow path 690 and between the recirculation flow path 680 and the exhaust flow path 610. The regeneration assistant valve 790 may be installed on the regeneration assistant flow path 690.

The bypass flow path 620 branches from the exhaust flow path 610 in front of the main valve 710 and can join the exhaust flow path 610 behind the auxiliary valve 730. The bypass valve 720 is installed on the bypass flow path 620.

With such a configuration, the selective catalytic reduction system 101 according to an embodiment of the present invention can effectively regenerate the poisoned catalyst 350. [

That is, the selective catalytic reduction system 101 forms a closed loop through the heating device 400 by utilizing the recycle passage 680 and the regeneration auxiliary passage 690 to regenerate the catalyst 350, It is possible to minimize the heat energy consumed for regenerating the heat exchanger. Also, the time required for raising the temperature of the catalyst 350 can be shortened.

In addition, according to an embodiment of the present invention, the flow of the fluid circulating through the closed loop, that is, the moving direction of the fluid, can be selectively controlled by utilizing the regeneration auxiliary flow path 690. Therefore, the regeneration of the catalyst 350 installed in the reactor 300 can be effectively performed.

Specifically, when the catalyst 350 disposed at the upstream side of the reactor 300 is preferentially regenerated, the fluid is circulated from the front end to the rear end side of the reactor 300 through the recirculation flow path 680.

When the catalyst 350 disposed at the rear end of the reactor 300 is preferentially regenerated, the fluid is moved through the regeneration assistant flow path 690. The fluid moving through the regeneration auxiliary flow path 690 indirectly heats the catalyst 350 disposed at the rear end of the reactor 300.

Also, according to an embodiment of the present invention, the exhaust gas of the diesel engine 200 may be discharged through the bypass flow path 620 during the operation of regenerating the catalyst 350. That is, a vessel having the selective catalytic reduction system 101 according to an embodiment of the present invention can regenerate the catalyst 350 during operation without anchoring or disabling the operation.

Hereinafter, the operation principle of the selective catalytic reduction system 101 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG.

The selective catalytic reduction system (101) according to an embodiment of the present invention can operate in either of a post-treatment mode and a catalyst regeneration mode.

As shown in FIG. 1, in the post-treatment mode, the exhaust gas discharged in the power generation process can be moved along the exhaust flow path 610 through the reactor 300. For example, the exhaust gas discharged in the power generation process may be the exhaust gas discharged from the diesel engine 200. That is, in the post-treatment mode, the exhaust gas of the diesel engine 200 can be post-treated for purification. Here, purification means reduction of nitrogen oxides contained in the exhaust gas.

Specifically, in the post-treatment mode, the main valve 710 and the auxiliary valve 730 are opened and the bypass valve 720 is closed. Then, the recirculation valve 780 is opened and the regeneration auxiliary valve 790 can be closed.

Further, the heating apparatus 400 can be operated when the temperature of the decomposition chamber 500, which generates the reducing agent in the post-treatment mode, becomes lower than the temperature at which the reducing agent can be generated.

In the catalyst regeneration mode, the exhaust gas discharged during the power generation process is moved along the bypass flow path 620 while bypassing the reactor 300. The heating device 400 heats the catalyst 350 installed in the reactor 300 to supply thermal energy necessary for decomposing and removing the catalyst poisoning substance. The reducing agent supply unit (550) stops the supply of the reducing agent precursor to the decomposition chamber (500).

Further, the catalyst regeneration mode includes a first regeneration mode, a second regeneration mode, and a third regeneration mode.

As shown in FIG. 2, the first regeneration mode can be activated when the catalyst 350 disposed at the upstream side of the reactor 300 is preferentially regenerated.

In the first regeneration mode, the main valve 710, the auxiliary valve 730, and the regeneration assistant valve 790 are closed and the recirculation valve 780 is opened. The bypass valve 720 is also opened. That is, in the first regeneration mode, a closed loop including a part of the exhaust flow path 610 and the recirculation flow path 680 and circulating between the heating device 400 and the reactor 300 can be formed . The blower 450 moves the fluid heated by the heating device 400 from the front end of the reactor 300 toward the rear end to circulate the closed loop.

As described above, the catalyst 350 may be poisoned by the catalyst poisoning material generated by the reaction of sulfur oxides (SOx) and ammonia (NH ₃ ) of the exhaust gas, and the activity may be lowered. In one example, the catalyst poisoning materials, such as ammonium sulfate _{(Ammonium sulfate, (NH 4)} 2 SO 4) and hydrogen sulfite, ammonium _{(Ammonium bisulfate, NH 4 HSO 4} ) is decomposed at a temperature in the range degrees to degrees Celsius to 450 degrees Celsius to 350. Therefore, when the catalyst 350 in the reactor 300 is heated with the fluid heated by the heating device 400, the catalyst poisoning material is decomposed and removed to restore the activity of the catalyst 350.

A closed loop formed in the first regeneration mode includes a part of the exhaust flow path 610 and the recirculation flow path 680 and is connected to the reactor 300 and the heating device 400, And the heating device 400 minimizes the thermal energy consumed by regenerating the catalyst 350 by heating the fluid circulating in the closed loop, thereby preventing waste of fuel.

In addition, when oxygen in the closed loop becomes insufficient due to the operation of the heating device 400, the outside air supply part 800 can be operated to supply the combustion air required for the heating device 400.

As described above, when the outside air supply part 800 is operated, the auxiliary valve 730 may be partially opened only if necessary. That is, when the outside air supply part 800 is activated, the auxiliary valve 730 can be partially closed. This is because when the outside air supply unit 800 continuously supplies outside air to the closed loop to supply the combustion air to the heating unit 400, the pressure of the closed loop can be raised. At this time, the auxiliary valve 730 may be partly opened to maintain the pressure of the closed loop within a safe range. Here, the safe range means that the exhaust system of the power unit and the selective catalytic reduction system 101 are within an allowable pressure at which they can be stably maintained.

As shown in FIG. 3, the second regeneration mode can be activated when the catalyst 350 disposed at the rear end of the reactor 300 is preferentially regenerated.

In the second regeneration mode, the main valve 710, the auxiliary valve 730, and the recirculation valve 780 are closed, and the regeneration auxiliary valve 790 is opened. And the bypass valve 9720) are also opened.

That is, in the second regeneration mode, a closed loop including a part of the exhaust passage 610, a part of the recycle passage 680, and the regeneration auxiliary passage 690 and passing through the heating device 400 can be formed . The blower 450 circulates the fluid heated by the heating device 400 in the closed loop.

At this time, since the joining point of the regeneration auxiliary flow path 690 and the exhaust flow path 610 is adjacent to the rear end of the reactor 300, the fluid heated by the heating device 400 flows from the regeneration auxiliary flow path 690 to the exhaust flow path 610 The catalyst 350 disposed at the rear end of the reactor 300 is indirectly heated by preferentially moving the catalyst 350 along the recirculation flow path 680. That is, as the heated fluid moves, it is heated from the catalyst 350 disposed at the rear end of the reactor 300 by a heat transfer method such as convection or radiation.

Further, the operations of the heating device 400, the outside air supply part 800, and the auxiliary valve 730 are the same as those in the first regeneration mode. In particular, the operation of the auxiliary valve 730 according to the operation of the outside air supply unit 800 is the same as that of the first regeneration mode.

As shown in FIG. 4, the third regeneration mode can be activated when regenerating the catalyst 350 disposed at the upstream and downstream sides of the reactor 300 with the same specific gravity.

In the third regeneration mode, the main valve 710 and the auxiliary valve 730 are closed, and the recirculation valve 780 and the regeneration auxiliary valve 790 are opened. The bypass valve 720 is also opened. That is, both the closed loop formed in the first reproduction mode and the closed loop formed in the second reproduction mode are formed in the third reproduction mode. The blower 450 circulates the fluid heated by the heating device 400 in the closed loop.

That is, in the second regeneration mode, a closed loop including a part of the exhaust passage 610, a part of the recycle passage 680, and the regeneration auxiliary passage 690 and passing through the heating device 400 can be formed . The blower 450 circulates the fluid heated by the heating device 400 to both of the closed loops simultaneously.

Thus, both the catalyst 350 disposed at the front end of the reactor 300 and the catalyst 350 disposed at the rear end of the reactor 300 can be effectively regenerated.

The operations of the heating device 400, the outside air supply part 800, and the auxiliary valve 730 are the same as those of the first regeneration mode and the second regeneration mode. In particular, the operation of the auxiliary valve 730 according to the operation of the outside air supply unit 800 is the same as the first regeneration mode and the second regeneration mode.

Also, the outside air supply part 800 can be operated even in the post-treatment mode when combustion air is required in the heating device 400. [

Also, according to one embodiment of the present invention, the exhaust gas discharged from the diesel engine 200 in the catalyst regeneration mode can travel along the bypass flow path 620 while bypassing the reactor 300. That is, in the catalyst regeneration mode, the exhaust gas of the diesel engine 200 can be discharged without post-treatment.

In the meantime, the present invention is not limited to the above-described embodiment. Even when the ship is not in the catalyst regeneration mode, if the ship is operated in a region other than the pollution region or the environment regulatory region, In an emergency, the exhaust gas of the diesel engine 200 can be discharged through the bypass flow path 620. In this case, the heating apparatus 400 is not operated.

By such operation, the selective catalytic reduction system 101 according to an embodiment of the present invention can effectively regenerate the poisoned catalyst 350. [

The exhaust gas may be gradually lowered through the plurality of catalysts 350 installed in the reactor 300 and the degree of poisoning of the catalyst 350 may vary depending on the position in the reactor 300.

Also, the catalyst 350 disposed at the upstream side of the reactor 300 is actively subjected to the reduction reaction more actively than the catalyst 350 disposed downstream of the reactor 300. This is because the concentration of nitrogen oxides contained in the exhaust gas is reduced while passing through the catalyst 350. Therefore, the lifetime or the activity of the catalyst 350 disposed at the upstream side of the reactor 300 can be lowered relatively rapidly as compared with the catalyst 350 disposed at the downstream side of the reactor 300.

In addition, the catalyst 350 disposed on the upstream side of the reactor 300 is liable to adhere to the catalyst 350 in addition to the catalyst poisoning substance.

Therefore, it is necessary to regenerate some of the catalysts 350 preferentially according to the positions of the plurality of catalysts 350 disposed in the reactor 300.

According to an embodiment of the present invention, selective regeneration of a plurality of catalysts 350 installed in the reactor 300 is possible.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. will be.

It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

101: Selective Catalytic Reduction System
200: Diesel engine
250: Supercharger
300: reactor
350: catalyst
400: Heating device
450: Blower
500: decomposition chamber
550: Reducing agent supply unit
570: Reducing agent dispensing part
610:
620: Bypass channel
680: Recirculation flow path
690:
710: Main valve
720: Bypass valve
730: auxiliary valve
780: recirculation valve
790: Regeneration auxiliary valve
800: outside air supply part

Claims (12)

An exhaust passage through which exhaust gas containing nitrogen oxides (NOx) discharged in the power generation process moves;
A reactor installed on the exhaust passage and having a catalyst therein;
A recirculation flow path branched from the exhaust flow path behind the reactor and joined to the branch flow path in front of the reactor;
A heating device installed on the recirculation flow path; And
A regeneration auxiliary flow path which branches from the recirculation flow path between the recirculation flow path and the exhaust flow path and between the recirculation flow path between the heating device and the exhaust flow path between the exhaust flow path and the branch point of the recirculation flow path and the rear end of the reactor,
≪ / RTI > The method according to claim 1,
A post-treatment mode in which the exhaust gas discharged in the power generation process moves through the reactor along the exhaust passage;
A catalyst regeneration mode for regenerating the catalyst of the reactor by forming a closed loop including the heating device;
The selective catalytic reduction system operating in any one of the two modes. 3. The method of claim 2,
A main valve provided in the exhaust passage in front of a junction point of the exhaust passage and the recirculation passage;
An auxiliary valve provided in the exhaust passage behind the branch point of the exhaust passage and the recirculation passage;
A recirculation valve provided on the recirculation flow path between a branch point of the recycle passage and the recycling auxiliary passage and a junction point of the recirculation passage and the exhaust passage; And
And a regeneration auxiliary valve
≪ / RTI > The method of claim 3,
In the after-treatment mode, the main valve, the auxiliary valve, and the recirculation valve are opened and the regeneration auxiliary valve is closed. The method of claim 3,
In the catalyst regeneration mode,
A first regeneration mode in which the main valve, the auxiliary valve, and the regeneration auxiliary valve are closed and the recirculation valve is opened;
A second regeneration mode in which the main valve, the auxiliary valve, and the recirculation valve are closed and the regeneration assisting valve is opened; And
The main valve and the auxiliary valve are closed, and the recycle valve and the regeneration auxiliary valve are opened,
≪ / RTI > The method of claim 3,
A bypass flow path branched from the exhaust flow path in front of the main valve and joined to the exhaust flow path behind the auxiliary valve;
And a bypass valve
≪ / RTI > The method according to claim 6,
Wherein the bypass valve is closed in the post-treatment mode and is open in the catalyst regeneration mode. The method of claim 3,
And an outside air supply unit connected to the recirculation flow path to supply oxygen necessary for the heating apparatus. 9. The method of claim 8,
And the auxiliary valve is at least partially opened when the outside air supply unit is activated. 10. The method according to any one of claims 1 to 9,
A decomposition chamber provided on the branch passage;
A reducing agent supply unit for supplying a reducing agent or a reducing agent precursor to the decomposition chamber;
≪ / RTI > 11. The method of claim 10,
And a blower provided on the branch passage. 11. The method of claim 10,
Wherein the heating apparatus is operated in the post-treatment mode in which the temperature of the decomposition chamber is below the reducing agent production temperature or in the catalyst regeneration mode.

Images