KR20160104367A - Power plant with selective catalytic reuction system - Google Patents

Abstract

The present invention relates to a power apparatus with a selective catalytic reduction system capable of reducing an installation space and maintenance costs by efficiently reducing nitrogen oxide contained in the exhaust gas discharged from multiple engines. According to an embodiment of the present invention, the power plant of the invention comprises: a first engine discharging exhaust gas containing nitrogen oxide (NOx); one or more second engines discharging exhaust gas containing nitrogen oxide (NOx) having a higher temperature than that of the first engine; a first exhaust flow passage through which the exhaust gas of the first engine flows; a second exhaust flow passage through which the exhaust gas of the second engine flows; a first reactor including a catalyst reducing nitrogen oxide included in the exhaust gas which is installed in the first exhaust flow passage; a second reactor including a catalyst reducing nitrogen oxide included in the exhaust gas which is installed in the second exhaust flow passage; a first reducing agent injection unit injecting a reducing agent into exhaust gas flowing toward the second reactor; and a single decomposition chamber generating a reducing agent to be supplied to the first and second reducing agent injecting units.

Description

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

The present invention relates to a power plant including a selective catalytic reduction system, and more particularly to a power plant including a selective catalytic reduction system using a plurality of engines.

Generally, a power unit used for a ship or the like includes a low speed diesel engine and a turbocharger.

In addition, in the case of a ship, there are many cases in which at least one auxiliary engine used as a power for power generation or the like is included in addition to the main engine used as a main power source. At this time, a medium speed diesel engine is mainly used as the auxiliary engine, and the exhaust gas emitted from the main engine of the low speed diesel engine and the auxiliary engine of the medium speed diesel engine are different in the temperature and the nitrogen oxide content.

On the other hand, the selective catalytic reduction (SCR) system is a system for reducing nitrogen oxides by purifying the exhaust gas generated from a diesel engine.

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.

This selective catalytic reduction system is required to be capable of satisfying the third regulation (IMO Tier-III) of engine international air pollution emission of NOx emitted from a marine diesel engine.

The selective catalytic reduction system is mainly used by pyrolysis and hydrolysis of urea as a reducing agent for reducing nitrogen oxides. At this time, in order to improve the efficiency of the thermolysis reaction, a method of raising the internal temperature of the pyrolysis chamber to a pyrolysis reaction temperature using a separate electric heater or a burner is used.

However, since there is not much energy consumed in pyrolysis, there is a problem that more energy is consumed than necessary in operation of the overall selective catalytic reduction system.

In addition, the ambient temperature and pyrolysis residence time for pyrolysis serve as very important factors. However, as the pyrolysis and residence time of urea increases, there is a problem that a deposit is generated.

Ammonia slip is generated when ammonia used as a reducing agent is injected more than necessary in order to satisfy the IMO Tier-III requirements of the engine international air pollution prevention regulations. Ammonia slip is a phenomenon in which unreacted ammonia, which has not participated in the reaction, is discharged together with the exhaust gas when a larger amount of ammonia is injected than the amount of ammonia reacting quantitatively with nitrogen oxides.

If ammonia slip occurs, unreacted ammonia may cause corrosion of the exhaust pipe, and if unreacted ammonia is discharged to the outside together with the exhaust gas, there may further be a problem of air pollution caused by ammonia.

On the other hand, when the injection amount of ammonia used as the reducing agent is insufficient, the nitrogen oxide contained in the exhaust gas can not be sufficiently reduced, thereby failing to satisfy the IMO Tier-III condition of the engine international air pollution prevention.

Therefore, it is required to operate a selective catalytic reduction system that not only satisfies the IMO Tier-III condition but also minimizes the occurrence of ammonia slip when the load fluctuates as well as at the initial stage of operation of the diesel engine .

In addition, since the exhaust gas discharged from the main engine of the low speed diesel engine and the auxiliary engine of the medium speed diesel engine are different in temperature and nitrogen oxide content, the selective catalytic reduction system for the main engine and the selective The catalytic reduction system is operating independently.

However, even though the installation space of the ship is limited, when the plurality of selective catalytic reduction systems are operated independently, there is a problem in that not only the installation space is excessively occupied but also the human resources for maintenance for each system are wasted.

An embodiment of the present invention is directed to a power unit including a selective catalytic reduction system capable of efficiently reducing nitrogen oxides contained in exhaust gas discharged from a plurality of engines and simplifying the configuration, Lt; / RTI >

According to an embodiment of the present invention, a power unit including a selective catalytic reduction system includes a first engine for exhausting exhaust gas containing nitrogen oxides (NOx), a nitrogen oxide (NOx) at a relatively higher temperature than the first engine, A first exhaust passage through which the exhaust gas of the first engine moves, a second exhaust passage through which the exhaust gas of the second engine moves, and a second exhaust passage through which the exhaust gas of the first engine moves, A second reactor provided on the exhaust flow path and including a catalyst for reducing nitrogen oxides contained in the exhaust gas; a second reactor provided on the second exhaust flow path and including a catalyst for reducing nitrogen oxides contained in the exhaust gas; A first reducing agent injecting unit injecting a reducing agent into the exhaust gas directed to the first reactor, a second reducing agent injecting unit injecting a reducing agent into the exhaust gas directed to the second reactor, And a single decomposition chamber for generating a reducing agent to be supplied to the first reducing agent spraying part and the second reducing agent spraying part.

The power unit including the selective catalytic reduction system includes a urea supply unit for supplying urea, which is a reducing agent precursor, to the single decomposition chamber, and a urea supply unit for branching a part of the exhaust gas passing through the first reactor from the first exhaust passage, A circulation flow path for recirculation to the single decomposition chamber, and an auxiliary heating member provided on the circulation flow path.

The auxiliary heating member may raise the exhaust gas supplied to the single decomposition chamber through the circulation channel to maintain the temperature within the range of 350 to 600 degrees Celsius.

The auxiliary heating member may include a burner, a fuel supply unit for supplying fuel to the burner, and a ring blower for supplying oxygen to the burner.

In the power plant including the selective catalytic reduction system, the exhaust flow rate and the nitrogen oxide concentration of the first engine and the exhaust flow rate and the nitrogen oxide concentration of the second engine are summed to generate a reducing agent in the single decomposition chamber by a required amount can do.

Further, the power unit including the selective catalytic reduction system may further include a urea direct diffusing unit for directly injecting urea into the exhaust gas directed to the second reactor, It is possible to selectively operate only at the same time.

In the case where the second engine is a plurality of engines, the urea direct injection engine may add the exhaust flow rate and the nitrogen oxide concentration of the plurality of second engines and adjust the injection amount of the urea according to the amount of the reducing agent required.

The power unit including the selective catalytic reduction system may further include a mixing duct disposed on the second exhaust passage, and the second reducing agent spraying unit and the urea direct diffusing unit are respectively connected to the mixing duct, And urea.

According to the embodiment of the present invention, the power unit including the selective catalytic reduction system efficiently reduces the nitrogen oxides contained in the exhaust gas discharged from the plurality of engines, simplifies the configuration, reduces the installation space required, .

1 is a configuration diagram of a power unit including a selective catalytic reduction system according to an embodiment of the present invention.
FIG. 2 is a configuration diagram illustrating an operation state of a power unit including the selective catalytic reduction system of FIG. 1. 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 a first engine 100, a second engine 200, The first reducing agent injecting section 710, the second reducing agent injecting section 720, and the single decomposition section 720. The first reducing agent injecting section 720 is provided in the first exhaust passage 610, the second exhaust passage 620, the first reactor 310, the second reactor 320, And a chamber (400).

The power unit 101 including the selective catalytic reduction system according to an embodiment of the present invention includes a urea supply unit 450, a circulation channel 630, an auxiliary heating member 500, a mixing duct 800, And a urea direct dividing section 740. [

The power unit 101 including the selective catalytic reduction system according to an embodiment of the present invention includes a circulation blower 550, a first injection flow channel 660, a second injection flow channel 670, and a supply blower 850, As shown in FIG.

The first engine 100 is a low-speed diesel engine used as a main power source for ships and the like. As the first engine 100, various engines known to those skilled in the art can be used. By way of example, a low speed diesel engine may be a two stroke diesel engine.

In one embodiment of the present invention, the first engine 100 exhausts exhaust gas containing nitrogen oxides (NOx).

Also, although not shown, the power unit 101 including a selective catalytic reduction (SCR) system according to an embodiment of the present invention may further include a supercharger.

The supercharger may be installed on the first exhaust passage 610 to be described later. The turbocharger boosts the efficiency of the first engine 100 by compressing and supplying fresh air to the first engine 100 by rotating the turbine with the pressure of the exhaust gas of the first engine 100

As described above, the temperature of the exhaust gas discharged from the first engine 100 is lowered to less than 250 degrees Celsius by more than 150 degrees Celsius through the supercharger.

The second engine 200 may be a medium speed diesel engine used as an auxiliary power source for power generation. That is, the second engine 200 can be used for power generation to generate electric power necessary for a ship or the like. For example, a medium speed diesel engine may be a four stroke diesel engine

In an embodiment of the present invention, the second engine 200 discharges exhaust gas containing nitrogen oxides (NOx), and the exhaust gas discharged by the second engine 200 is discharged from the first engine 100 And has a relatively higher temperature than the exhaust gas. For example, the second engine 200 may exhaust exhaust gas having a temperature in the range of 250 degrees Celsius to 450 degrees Celsius.

Further, in one embodiment of the present invention, at least one second engine 200 may be provided.

The first exhaust passage 610 discharges the exhaust gas discharged from the first engine 100. That is, the exhaust gas discharged from the first engine 100 moves along the first exhaust flow path 610.

The second exhaust passage 620 discharges the exhaust gas discharged from the second engine 200. That is, the exhaust gas discharged from the second engine 200 moves along the second exhaust passage 620.

When a plurality of second engines 200 are used, the exhaust gases discharged from the plurality of second engines 200 join together and move along the second exhaust passage 620.

The first reactor 310 is installed on the first exhaust passage 610. The first reactor 310 includes a catalyst for reducing nitrogen oxides (NOx) contained in the exhaust gas discharged from the first engine 100.

The second reactor 320 is installed on the second exhaust passage 620. The second reactor 320 includes a catalyst for reducing nitrogen oxides (NOx) contained in the exhaust gas discharged from the second engine 200.

The catalyst provided in each of the first reactor 310 and the second reactor 320 promotes the reaction of the reducing agent with the nitrogen oxide (NOx) contained in the exhaust gas to reduce the nitrogen oxide (NOx) into 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 active temperature range, the efficiency decreases as it is poisoned.

In addition, the housings of the first reactor 310 and the second reactor 320 may be made of, for example, stainless steel.

The first reducing agent spraying part 710 injects the reducing agent into the exhaust gas moving to the first reactor 310 along the first exhaust flow path 610. Specifically, the first reducing agent spraying portion 710 may be installed on the first exhaust passage 610 in front of the first reactor 310. The reducing agent injected from the first reducing agent injecting portion 710 is mixed with the exhaust gas flowing through the first exhaust gas passage 610, and then the nitrogen oxide is reduced in the catalyst of the first reactor 310.

The second reducing agent injecting section 720 injects the reducing agent into the exhaust gas moving to the second reactor 320 along the second exhaust gas passage 620. Specifically, the second reducing agent injecting section 720 may be installed on the second exhaust passage 620 in front of the second reactor 320. The reducing agent injected from the second reducing agent injecting portion 720 is mixed with the exhaust gas moving through the second exhaust gas passage 620, and then the nitrogen oxide is reduced in the catalyst of the second reactor 320.

The reducing agent injected from the first reducing agent spraying part 710 and the second reducing agent spraying part 720 includes ammonia (NH ₃ ).

The single decomposition chamber 400 generates a reducing agent to be supplied to the first reducing agent spraying unit 710 and the second reducing agent spraying unit 720. The single decomposition chamber 400 receives urea (CO (NH ₂ ) ₂ ) as a reducing agent precursor and hydrolyzes it to produce ammonia (NH ₃ ) as a reducing agent.

When the temperature in the single decomposition chamber 400 maintained within Celsius 300 degrees to degrees Celsius to 500 degrees, while the urea is decomposed easily hydrolysis is ammonia (NH ₃₎ and isocyanate (Isocyanic acid, HNCO) is generated, and isocyanate (HNCO) is decomposed again into ammonia (NH ₃ ) and carbon dioxide (CO ₂ ).

The urea supply unit 450 supplies urea (CO (NH ₂ ) ₂ ), which is a reducing agent precursor, to the single decomposition chamber 400. The urea supply unit 450 supplies an appropriate amount of urea to the single decomposition chamber 400 in consideration of the amount of the reducing agent required to vary depending on the loads of the first engine 100 and the second engine 200.

That is, the exhaust gas flow rate and the nitrogen oxide concentration of the first engine 100, the exhaust gas flow rate of the second engine 200, and the nitrogen oxide concentration are summed to generate the reducing agent in the single decomposition chamber 400, The urea supply unit 450 can supply the urea in accordance with the amount of the reducing agent required under the control of the control unit (not shown).

Here, the control unit may be an electronic control unit (ECU) of the engine or a separate control unit.

The exhaust flow rate and the nitrogen oxide concentration of the first engine 100 and the second engine 200 may be measured using a separate sensor or may be estimated using mapping results from the engine. The mapping of the engine to the electronic control device controlling the engine can be performed using various methods known to those skilled in the art.

The circulation flow passage 630 divides a part of the exhaust gas passing through the first reactor 310 in the first exhaust flow passage 610 and recycles it to the single decomposition chamber 400.

The auxiliary heating member 500 is installed on the circulating flow path 630. The auxiliary heating member 500 heats the exhaust gas passing through the first reactor 310 supplied to the single decomposition chamber 400 through the circulation flow path 630 to raise the temperature to a temperature sufficient to generate the reducing agent. For example, the auxiliary heating member 500 raises the exhaust gas supplied to the single decomposition chamber 400 through the circulation channel 630 to maintain the temperature within the range of 350 ° C. to 600 ° C.

Since the exhaust gas supplied to the first reactor 310 is supplied mainly to the activation temperature of the catalyst, the exhaust gas passing through the first reactor 310 may have a temperature within a range of about 200 degrees Celsius to about 350 degrees Celsius.

Therefore, according to the embodiment of the present invention, since the auxiliary heating member 500 supplies auxiliary thermal energy to the exhaust gas passing through the first reactor 310 to elevate the temperature to the hydrolysis of the urea, It is possible to minimize the energy consumed.

In one embodiment of the present invention, the auxiliary heating member 500 includes a burner 510, a fuel supply unit 520 for supplying fuel to the burner 510, and a ring blower 520 for supplying oxygen to the burner 510. [ 530 < / RTI >

Since the exhaust gas recycled after passing through the first reactor 310 has a low concentration of oxygen, burning of the burner 510 may not be smooth, so that the auxiliary heating member 500 according to an embodiment of the present invention replenishes oxygen And a ring blower 530 for supplying outside air to the outside.

The circulation blower 550 is installed on the circulation flow path 630. The circulation blower 550 blows the exhaust gas through the circulation flow path 630 to supply the exhaust gas to the single decomposition chamber 400.

The first injection path 660 connects the single decomposition chamber 400 and the first reducing agent spray part 710 and the second spray path 670 connects the single decomposition chamber 400 and the second reducing agent spray part 720, Lt; / RTI >

The supply blower 850 is provided on the second injection path 670 to smoothly supply the reducing agent generated in the single decomposition chamber 400 to the second reducing agent spraying unit 720.

The urea direct fractionator 740 can directly separate urea from the exhaust gas flowing into the second reactor 320 along the second exhaust gas passage 610. For example, the urea direct fractionator 740 may be installed on the second exhaust passage 620 in front of the second reactor 320. The urea injected from the urea direct fractionator 740 is decomposed into the reducing agent while moving along the second exhaust passage 620.

In addition, the urea direct finishing section 740 can receive urea from the urea supply section 450 that supplies urea to the single decomposition chamber 400.

The exhaust gas discharged from the second engine 200 is transferred to the second exhaust passage 620 and the exhaust gas of the second engine 200 is exhausted from the exhaust gas having a relatively high temperature, that is, a temperature within the range of 250 degrees Celsius to 450 degrees Celsius So that the exhaust gas is moved.

Therefore, the urea injected through the urea direct diffusing portion 740 to the exhaust gas moving along the second exhaust gas passage 620 can be easily decomposed by the reducing agent.

In a preferred embodiment of the present invention, when the number of the second engines 200 is plural, the urea direct dividing section 740 sums up the exhaust flow rate and the nitrogen oxide concentration of the plurality of second engines 200, The amount of urea injected can be adjusted according to the amount.

At this time, the exhaust flow rate and the nitrogen oxide concentration of the plurality of second engines 200 may be measured using a separate sensor or may be estimated using mapping results from the engine. The mapping of the engine to the electronic control device controlling the engine can be performed using various methods known to those skilled in the art.

A mixing duct 800 is installed on the second exhaust passage 620. The second reducing agent spraying part 720 and the urea spraying part 740 spray the reducing agent and the urea to the mixing duct 800, respectively.

Thus, the reducing agent and the urea injected from the second reducing agent injecting section 720 and the urea injecting section 740 can be smoothly mixed with the exhaust gas moving along the second exhaust gas passage 620.

With this configuration, the power unit 101 including the selective catalytic reduction system according to the embodiment of the present invention efficiently reduces nitrogen oxides contained in the exhaust gas discharged from the plurality of engines 100 and 200 To reduce the required installation space and reduce maintenance costs.

Specifically, the power plant 101 including the selective catalytic reduction system according to an embodiment of the present invention includes a first reactor 310 optimized for the first engine 100 and a second reactor 200 optimized for the second engine 200, (320). However, since the reducing agent necessary for the selective catalytic reduction reaction is generated and supplied in one single decomposition chamber (400), it is possible to minimize the overall installation configuration and installation space required for generating the reducing agent.

Also, in an embodiment of the present invention, in consideration of the second engine 200 that is operated even when the first engine 100 is not operated, that is, unlike the first engine 100 used at the time of operating the ship, And a urea direct sheath portion 740 provided to reduce nitrogen oxides of the exhaust gas discharged from the second engine 200, which is also used in berths.

The urea direct dividing section 740 selectively operates when the second engine 200 is running but the first engine 100 is stopped. The urea direct fractionator 740 can receive urea from the urea supply unit 450 that supplies urea to the single decomposition chamber 400.

In addition, the urea direct sheath portion 740 is a device for directly separating urea from the mixing duct 800, which not only simplifies the structure but also takes up less installation space.

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 and 2. FIG.

1 shows a state in which both the first engine 100 and the second engine 200 are in operation.

1, in a state in which both the first engine 100 and the second engine 200 are in operation, the exhaust gas from the first engine 100 through the first reactor 310 and the exhaust gas from the auxiliary heating member 500 to generate a reducing agent in the single decomposition chamber 400 and supply the reducing agent to the first reducing agent spraying unit 710 and the second reducing agent spraying unit 720.

2 shows a state in which the operation of the first engine 100 is stopped and only the second engine 200 is in operation.

2, since the exhaust gas discharged from the first engine 100 can not be used when the first engine 100 is stopped, the second engine 200 can be operated through the urea direct- The urea is directly fed into the exhaust gas discharged from the exhaust gas recirculation system.

The exhaust gas discharged from the second engine 200 is close to a temperature suitable for decomposition of the urea. Therefore, in order to supply the reducing agent only to the exhaust gas discharged from the second engine 200, It is effective to remove urea directly from the gas.

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
100: First engine
200: Second engine
310: first reactor
320: second reactor
400: single decomposition chamber
450: urea supply part
500: auxiliary heating member
510: Burner
520: fuel supply unit
530: ring blower
550: Circular blower
610: a first exhaust passage
620: the second exhaust passage
630:
660: First injection channel
670: First injection channel
710: First reducing agent spraying part
720: Second reducing agent spraying part
740: urea direct division
800: Mixing duct
850: Feed blower

Claims (8)

A first engine for exhausting an exhaust gas containing nitrogen oxides (NOx);
At least one second engine for exhausting an exhaust gas containing nitrogen oxide (NOx) at a relatively higher temperature than the first engine;
A first exhaust passage through which the exhaust gas of the first engine moves;
A second exhaust passage through which the exhaust gas of the second engine moves;
A first reactor provided on the first exhaust flow path and including a catalyst for reducing nitrogen oxides contained in the exhaust gas;
A second reactor provided on the second exhaust passage and containing a catalyst for reducing nitrogen oxides contained in the exhaust gas;
A first reducing agent injecting unit injecting a reducing agent into the exhaust gas directed to the first reactor;
A second reducing agent injecting unit injecting a reducing agent into the exhaust gas directed to the second reactor; And
A first decomposing chamber for generating a reducing agent to be supplied to the first reducing agent spraying part and the second reducing agent spraying part,
≪ / RTI > The method according to claim 1,
A urea supply unit for supplying a urea which is a reducing agent precursor to the single decomposition chamber;
A circulation passage for branching a part of the exhaust gas passing through the first reactor in the first exhaust passage and recirculating the part of exhaust gas to the single decomposition chamber; And
The auxiliary heating member
Further comprising a selective catalytic reduction system. 3. The method of claim 2,
Wherein the auxiliary heating member heats the exhaust gas supplied to the single decomposition chamber through the circulation channel to maintain the exhaust gas within a temperature range of about 350 degrees Celsius to about 600 degrees Celsius. 3. The method of claim 2,
The auxiliary heating member
A burner;
A fuel supply unit for supplying fuel to the burner; And
A ring blower for supplying oxygen to the burner
≪ / RTI > The method according to claim 1,
And a selective catalytic reduction system for producing a reducing agent in the single decomposition chamber by summing the exhaust flow rate and the nitrogen oxide concentration of the first engine and the exhaust flow rate and the nitrogen oxide concentration of the second engine. 6. The method according to any one of claims 1 to 5,
Further comprising a urea direct diffusing part for directly injecting urea into the exhaust gas toward the second reactor,
Wherein the urea direct fractionator includes a selective catalytic reduction system that selectively operates only at the same time as the first engine. The method according to claim 6,
Wherein the urea direct fractionation section is a power generation section that includes a selective catalytic reduction system for regulating an injection amount of urea in accordance with an amount of a reducing agent required by summing an exhaust flow rate and a nitrogen oxide concentration of a plurality of the second engines when the second engine is a plurality Device. The method according to claim 6,
Further comprising a mixing duct disposed on the second exhaust passage,
Wherein the second reducing agent spraying portion and the urea direct diffusing portion each include a selective catalytic reduction system for spraying a reducing agent and urea to the mixing duct.

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