KR20170059159A - Power plant with selective catalytic reuction system - Google Patents

Abstract

The present invention relates to power equipment including a selective catalytic reduction system, capable of effectively reproducing a poisoned catalyst. According to one embodiment of the present invention, the power equipment comprises: an engine to discharge exhaust gas including NO_x; a discharge passage through which the exhaust gas discharged from the engine moves; a reactor installed on the discharge passage and having a catalyst installed therein; a branch passage branched from the discharge passage in front of the reactor to connect to the reactor; a bypass passage branched from the discharge passage and the discharge passage in front of a branching position of the branch passage to join with the discharge passage in the rear of the reactor; and a heating device installed on the branch passage.

Description

[0001] POWER PLANT WITH SELECTIVE CATALYTIC REUCTION SYSTEM [0002]

The present invention relates to a power plant including 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 power plant with a selective catalytic reduction system capable of effectively regenerating a poisoned catalyst.

According to an embodiment of the present invention, a power unit including a selective catalytic reduction system includes an engine for exhausting exhaust gas containing nitrogen oxides (NOx), an exhaust passage through which the exhaust gas discharged from the engine moves, A branching flow path branched from the exhaust flow path in front of the reactor and connected to the reactor and branched from the exhaust flow path in front of a branch point of the exhaust flow path and the branch flow path, A bypass passage joined to the exhaust passage in the rear side; And a heating device provided on the branch passage.

A power plant including the selective catalytic reduction system includes a post-treatment operating mode in which exhaust gas of the engine moves along the exhaust passage through the reactor, and exhaust gas of the engine bypasses the reactor along the bypass passage. And a catalyst regeneration mode in which a catalyst in the reactor is regenerated by forming a closed loop including the heating device and the reactor.

The closed loop formed in the catalyst regeneration mode may include a part of the exhaust passage, the branch passage, and the bypass passage, and may be formed to circulate between the reactor and the heating device.

The power plant including the selective catalytic reduction system includes a main valve provided in the exhaust passage between a branch point of the exhaust passage and the bypass passage and a branch point of the exhaust passage and the branch passage, A first closed loop valve installed in the exhaust passage in front of a branch point of the exhaust passage and the bypass passage and a second closed loop valve provided in the exhaust passage behind the junction point of the exhaust passage and the bypass passage, 2 closed loop valve.

In the after-treatment operation mode, the main valve, the first closed-loop valve, and the second closed-loop valve are opened and the bypass valve can be closed. And in the postprocessing non-active mode, the first closed loop valve, the second closed loop valve, and the bypass valve are open and the main valve is closed. In the catalyst regeneration mode, the main valve and the bypass valve are opened, the first closed-loop valve is closed, and the second closed-loop valve is closed or only partially opened.

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

The power unit including the selective catalytic reduction system described above may further include an outside air supply unit connected to the branch flow path to supply outside air to the heating apparatus.

The power unit including 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 to the decomposition chamber.

The heating apparatus may be operated in the post-treatment operation mode in which the temperature of the decomposition chamber is lower than the reducing agent production temperature or in the catalyst regeneration mode.

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

1 is a configuration diagram of a power unit including a selective catalytic reduction system according to an embodiment of the present invention.
FIGS. 2 to 4 are block diagrams illustrating an operation state of the power unit including 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 power unit 101 including a selective catalytic reduction (SCR) system according to an embodiment of the present invention will be described with reference to FIG.

1, a power unit 101 including a selective catalytic reduction (SCR) system according to an embodiment of the present invention includes an engine 200, an exhaust passage 610, a reactor 300, A branch flow passage 640, a bypass flow passage 620, and a heating device 400.

The power unit 101 including the selective catalytic reduction system according to an embodiment of the present invention includes a blower 450, an outside air supply unit 800, a decomposition chamber 500, a reducing agent supply unit 550, a reducing agent spraying unit 570 ), And a supercharger 250, as shown in FIG.

Further, the power unit 101 including the selective catalytic reduction system according to the embodiment of the present invention includes a main valve 710, a bypass valve 720, a first closed loop valve 760, a second closed loop valve 760, 780), and an auxiliary valve (730).

The engine 200 can be used as a main power source for supplying a propulsion force to a ship or a vehicle. As an example, the engine 210 may be a marine two-stroke low-speed diesel engine. As the engine 200, various types of engines known to those skilled in the art can be used.

Further, in one embodiment of the present invention, the engine 200 exhausts exhaust gas containing nitrogen oxides (NOx).

The supercharger 250 is connected to the exhaust port of the engine 200 to rotate the turbine with the pressure of the exhaust gas of the engine 200 to compress and supply new external air to the engine 200. Thus, the efficiency of the engine 200 equipped with the turbocharger 250 is improved. However, the turbocharger 250 may be omitted as needed and may be installed at various locations as is known to those skilled in the art.

In one embodiment of the present invention, the exhaust gas discharged from the 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.

The exhaust passage 610 is connected to the exhaust port of the engine 200 to exhaust the exhaust gas of the engine 200. When the turbocharger 250 is mounted, the exhaust passage 610 can sequentially connect the engine 200, the turbocharger 250, and the reactor 300, which will be described later. That is, the exhaust gas of the engine 200 moves along the exhaust flow path 610. Thus, the exhaust flow path 610 supplies the exhaust gas of the engine 200 to the reactor 300.

The reactor 300 is installed on the exhaust passage 610. The reactor 300 includes a catalyst for reducing nitrogen oxides (NOx) contained in the exhaust gas discharged from the engine 200. The catalyst promotes the reaction of the reducing agent with the nitrogen oxides (NOx) contained in the exhaust gas and reduces the nitrogen oxides (NOx) to nitrogen and water vapor.

The catalyst may be made of a variety of materials known to those skilled in the art, such as zeolite, vanadium, and platinum. In one example, the catalyst 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 can be stably reduced without being poisoned. When the catalyst reacts outside the activation temperature range, the catalyst 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 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 material is adsorbed on the catalyst to lower the activity of the catalyst. 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 in the reactor 300 can be heated to regenerate the poisoned catalyst.

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.

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

The branch flow path 640 branches from the exhaust flow path 610 in front of the reactor 300 and is connected to the reactor 300.

At this time, the connection between the reactor 300 and the branch passage 640 may be indirectly connected by joining the branch passage 640 to the exhaust passage 610 from the front of the reactor 300 or by connecting the branch passage 640 to the reactor 300, As shown in FIG.

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 4000 is installed on the branch passage 640. When the heating device 400 is operated, a part of the fluid flowing in the branch flow path 640, that is, the exhaust gas discharged from the engine 200, 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 for decomposing the reducing agent or for regenerating the catalyst provided in the reactor 300.

The blower 450 can be installed on the branch passage 640, like the heating device 400. The blower 450 can control the flow rate and the flow rate of the fluid moving along the branch flow path 640.

The outside air supply part 800 may be connected to the branch flow path 640 to supply outside air to the heating device 400. [ That is, the outside air supply unit 800 can supply outside air to the branch flow path 640 to supply oxygen necessary for operating the heating apparatus 400.

For example, the outside air supply unit 800 may include an outside air supply passage 810 for injecting outside air and an outside air supply valve 870 for opening and closing the outside air supply passage 810.

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 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. The 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 in the reactor 300. For example, the reducing agent spraying section 570 can be installed at the junction point of the branch passage 640 and the exhaust passage.

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 the reducing agent that varies depending on the load of the 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 bypass flow path 620 branches from the exhaust flow path 610 in front of the reactor 300 and merges with the exhaust flow path 610 in the rear of the reactor 300. The bypass valve 720 is installed on the bypass flow path 620 to open / close the bypass flow path 620.

The main valve 710 is installed in an exhaust passage 610 between a branch point of the exhaust passage 610 and the bypass passage 620 and a branch point of the exhaust passage 620 and the branch passage 640. The auxiliary valve 730 is installed at the confluence point of the bypass flow path 620 and the exhaust flow path 610 and in the exhaust flow path 610 between the reactor 300 and the reactor 300. 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 first closed-loop valve 760 is installed in the exhaust passage 610 in front of the branching point of the exhaust passage 610 and the bypass passage 620. The second closed loop valve 780 is installed in the exhaust passage 610 behind the junction point of the exhaust passage 610 and the bypass passage 620.

The first closed loop valve 760 and the second closed loop valve 780 are closed and the main valve 710, the auxiliary valve 730 and the bypass valve 720 are opened, A closed loop formed to circulate between the reactor 300 and the heating device 400, including a part of the fluid, the branch flow channel 640, and the bypass flow channel 640, may be formed.

With this configuration, the power unit 101 including the selective catalytic reduction system according to an embodiment of the present invention can effectively regenerate the poisoned catalyst.

That is, by forming a closed loop that can circulate between the reactor 300 and the heating device 400 by utilizing the branch channel 640 and the bypass channel 620, the thermal energy consumed for regenerating the catalyst can be minimized . Further, the time required for raising the temperature of the catalyst can be shortened.

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

The power unit 101 including the selective catalytic reduction system according to an embodiment of the present invention can be divided into a post-treatment mode, a post-treatment non-active mode, and a catalyst regeneration mode.

1, the exhaust gas of the engine 200 can be moved along the exhaust flow path 610 through the reactor 300 in the post-processing operation mode. That is, in the post-processing operation mode, the exhaust gas of the engine 200 can be post-treated for purification.

Specifically, in the after-treatment operation mode, the main valve 710, the auxiliary valve 730, the first closed-loop valve 760, and the second closed-loop valve 780 are opened and the bypass valve 720 is closed .

In addition, the heating device 400 can be operated when the temperature of the decomposition chamber 500 generating the reducing agent in the post-treatment operating mode becomes lower than the temperature at which the reducing agent can be generated.

If the fluid flowing through the branch flow path 640 lacks oxygen required for the heating apparatus 400 after the heating apparatus 400 is operated, the outside air supply unit 800 supplies the outside air to supply the combustion air required for the heating apparatus 400 Can be supplemented.

As shown in FIG. 2, in the post-processing non-operating mode, the exhaust gas of the engine 200 can travel along the bypass flow path 720 and bypass the reactor 300. That is, in the post-processing non-operating mode, the exhaust gas of the engine 200 can be discharged without being post-processed. If the ship is operated in a non-pollution zone or in an environment-restricted area, or if the selective catalytic reduction system fails, but can not be regenerated, it may operate in a postprocessing-inactive mode.

The first closed loop valve 760, the second closed loop valve 780 and the bypass valve 720 are opened and the main valve 710 and the auxiliary valve 730 are opened Can be closed. At this time, the auxiliary valve 730 can prevent the part of the exhaust gas moving along the bypass flow path 620 from flowing back to the reactor 300 in the post-treatment non-operating mode.

Further, the heating device 400 and the outside air supply part 800 are not operated in the postprocessing non-operating mode.

As shown in FIG. 3, in the catalyst regeneration mode, a closed loop including the heating apparatus 400 and the reactor 300 may be formed to heat and regenerate the catalyst in the reactor 300.

As described above, the catalyst may be poisoned by the catalyst poisoning material produced 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 in the reactor 300 is heated, the activity of the catalyst can be restored by removing the catalyst poisoning substance.

The closed loop formed in the catalyst regeneration mode includes a part of the exhaust flow path 610 and the branch flow path 640 and the bypass flow path 620. The reactor 300 and the heating device 400 As shown in Fig.

Thus, by forming a closed loop and heating the fluid circulating through the closed loop of the heating device 400, the thermal energy consumed for regenerating the catalyst can be minimized, and waste of fuel can be prevented.

Specifically, in the catalyst regeneration mode, the main valve 710, the auxiliary valve 730, and the bypass valve 720 are opened, the first closed loop valve 760 is closed, the second closed loop valve 780 is closed, May be closed or only partially open. And the heating device 400 is operated in the catalyst regeneration mode.

4, when the oxygen in the closed loop becomes insufficient due to the operation of the heating apparatus 400, the outside air supply unit 800 can be operated to supply the combustion air required for the heating apparatus 400. [

In this way, when the outside air supply unit 800 continuously supplies outside air to the closed loop to supply the combustion air to the heating apparatus 400, the pressure of the closed loop can be raised.

At this time, it is possible to partially open the second closed loop valve 780 to keep the pressure of the closed loop within a safe range. Here, the safe range means within the allowable pressure that the exhaust system and the selective catalytic reduction system can be stably maintained.

By this operation, the power unit 101 including the selective catalytic reduction system according to the embodiment of the present invention can effectively regenerate the poisoned catalyst.

That is, by forming a closed loop that can circulate between the reactor 300 and the heating device 400 by utilizing the branch channel 640 and the bypass channel 620, the thermal energy consumed for regenerating the catalyst can be minimized . Further, the time required for raising the temperature of the catalyst can be shortened.

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: Power unit including selective catalytic reduction system
200: engine
250: Supercharger
300: reactor
400: Heating device
450: Blower
500: decomposition chamber
550: Reducing agent supply unit
570: Reducing agent dispensing part
610: Main exhaust channel
620: Bypass channel
640:
710: Main valve
720: Bypass valve
730: auxiliary valve
760: First closed-loop valve
780: Second closed-loop valve
800: outside air supply part
810: Outdoor supply line
870: Outdoor supply valve

Claims (9)

An engine for exhausting exhaust gas containing nitrogen oxides (NOx);
An exhaust passage through which the exhaust gas discharged from the engine moves;
A reactor installed on the exhaust passage and having a catalyst therein;
A branch flow path branching from the exhaust flow path in front of the reactor and connected to the reactor;
A bypass passage branched from the exhaust passage in front of a branch point of the exhaust passage and the branch passage and merging with the exhaust passage in the rear of the reactor; And
A heating device
≪ / RTI > The method according to claim 1,
A post-treatment operating mode in which the exhaust gas of the engine moves along the exhaust passage via the reactor;
A post-treatment non-operating mode in which the exhaust gas of the engine travels along the bypass passage to bypass the reactor; And
A catalyst regeneration mode for regenerating a catalyst in the reactor by forming a closed loop including the heating device and the reactor;
And a selective catalytic reduction system operating in any one of the two modes. 3. The method of claim 2,
Wherein the closed loop formed in the catalyst regeneration mode includes a part of the exhaust passage, the branch passage, and the bypass passage and is arranged to circulate between the reactor and the heating device, Lt; / RTI > 3. The method of claim 2,
A main valve provided in the exhaust passage between a branch point of the exhaust passage and the bypass passage and a branch point of the exhaust passage and the branch passage;
A bypass valve provided on the bypass passage;
A first closed loop valve provided in the exhaust passage in front of a branch point of the exhaust passage and the bypass passage; And
A second closed loop valve installed in the exhaust passage behind the junction of the exhaust passage and the bypass passage,
Further comprising a selective catalytic reduction system. 5. The method of claim 4,
In the after-treatment operation mode, the main valve, the first closed-loop valve, and the second closed-loop valve are opened and the bypass valve is closed,
In the postprocessing non-active mode, the first closed-loop valve, the second closed-loop valve, and the bypass valve are opened and the main valve is closed,
Wherein in the catalyst regeneration mode the main valve and the bypass valve are open and the first closed loop valve is closed and the second closed loop valve is closed or only partially opened. The method according to claim 1,
And a blower provided on the branch passage. The method according to claim 1,
And an outside air supply unit connected to the branch flow path to supply outside air to the heating apparatus. 8. The method according to any one of claims 1 to 7,
A decomposition chamber provided on the branch passage;
A reducing agent supply unit for supplying a reducing agent to the decomposition chamber,
Further comprising a selective catalytic reduction system. 9. The method of claim 8,
Wherein the heating device includes a selective catalytic reduction system in which the temperature of the decomposition chamber is lower than or equal to a reducing agent production temperature in the post-treatment operation mode.

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