KR20160064422A - Apparatus for controlling supplying of reducing agent in selective catalytic reduction system - Google Patents

Apparatus for controlling supplying of reducing agent in selective catalytic reduction system Download PDF

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KR20160064422A
KR20160064422A KR1020140168008A KR20140168008A KR20160064422A KR 20160064422 A KR20160064422 A KR 20160064422A KR 1020140168008 A KR1020140168008 A KR 1020140168008A KR 20140168008 A KR20140168008 A KR 20140168008A KR 20160064422 A KR20160064422 A KR 20160064422A
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reducing agent
nitrogen oxide
amount
supply amount
nitrogen
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KR1020140168008A
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Korean (ko)
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성삼경
이상억
김승훈
김도윤
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현대중공업 주식회사
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/36—Arrangements for supply of additional fuel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

The present invention relates to an apparatus for controlling a supply amount of a reducing agent in an SCR system which can optimize the supply amount of the reducing agent using characteristics of a zirconia (ZrO_2) sensor measuring an amount of nitrogen oxide (NO_x). The apparatus for controlling the supply amount of a reducing agent in an SCR system according to the present invention comprises: an SCR reactor providing a space in which reducing reaction of the nitrogen oxide is processed by the reducing agent; a reducing agent supply device supplying the reducing agent to the SCR reactor; a nitrogen oxide detection sensor detecting an amount of the nitrogen oxide (NO_x) contained in exhaust gas discharged from the SCR reactor; and a control unit checking a nitrogen oxide change according to the supply amount of the reducing agent based on information on the supply amount of the reducing agent supplied to the SCR reactor by the reducing agent supply device and nitrogen oxide detection information measured by the nitrogen oxide detection sensor, and if the nitrogen oxide is increased until a second point after a first point of the supply amount of the reducing agent, recognizing the first point as an inflection point to control the supply amount of the reducing agent, supplied by the reducing agent supply device, to be the supply amount of the reducing agent at the first point.

Description

SCR 시스템의 환원제 공급량 제어장치{Apparatus for controlling supplying of reducing agent in selective catalytic reduction system}TECHNICAL FIELD The present invention relates to an apparatus for controlling the amount of reducing agent supplied to an SCR system,

본 발명은 SCR 시스템의 환원제 공급량 제어장치에 관한 것으로서, 보다 상세하게는 질소산화물(NOx)의 양을 측정하는 지르코니아(ZrO2) 센서의 특성을 이용하여 환원제 공급량을 최적화할 수 있는 SCR 시스템의 환원제 공급량 제어장치에 관한 것이다.
The present invention relates to a reducing agent supply amount control apparatus for a SCR system, and more particularly, the SCR system to optimize the reducing agent supply amount by using the properties of zirconia (ZrO 2) sensor that measures the amount of nitrogen oxide (NO x) And a reducing agent supply amount control apparatus.

선박의 배기가스에 포함되어 있는 질소산화물(NOx) 및 황산화물은 국제해사기구(IMO, International Maritime Organization)에 의해 배출규제를 받고 있는 대표적인 대기오염물질이다. Nitrogen oxides (NO x ) and sulfur oxides contained in the ship's exhaust are representative air pollutants subject to emission regulation by the International Maritime Organization (IMO).

질소산화물을 제거하기 위해 선박에는 통상, 선택적촉매환원 장치(selective catalytic reduction system)(이하, SCR 장치라 함)가 구비된다. SCR 장치는 촉매가 내장된 SCR 반응기, SCR 반응기 내에 요소수(尿素水)와 같은 환원제를 공급하는 환원제 공급장치를 구비한다. In order to remove nitrogen oxide, a ship is usually equipped with a selective catalytic reduction system (hereinafter referred to as SCR device). The SCR apparatus includes a SCR reactor having a catalyst and a reducing agent supply unit for supplying a reducing agent such as urea water into the SCR reactor.

SCR 장치에 의한 질소산화물 제거는 다음과 같은 과정으로 진행된다. 엔진의 배기가스가 SCR 반응기에 유입되는 상태에서 SCR 반응기 내에 환원제가 공급되면, 환원제가 배기가스와 섞여 촉매를 통과하게 되며 촉매를 통과하는 과정에서 환원제로부터 가수분해된 암모니아(NH3)가 배기가스 내의 질소산화물(NOx)과 반응하여 질소산화물(NOx)이 질소(N2)와 수증기로 환원된다. The removal of nitrogen oxide by the SCR apparatus proceeds as follows. When the reducing agent is supplied to the SCR reactor while the exhaust gas of the engine is flowing into the SCR reactor, the reducing agent is mixed with the exhaust gas and passes through the catalyst. During the passage through the catalyst, ammonia (NH 3 ) reacts with the nitrogen in the oxide (NO x) of nitrogen oxides (NO x) are reduced to nitrogen (N 2) and water vapor.

SCR 반응기 내에 공급되는 환원제의 공급량이 증가되면 질소산화물(NOx)도 그에 비례하여 감소된다. 그러나, 환원제 공급량이 일정 수준을 넘어서게 되면 질소산화물(NOx)의 감소는 정체되며, 이는 미반응 환원제의 양이 증가됨을 의미한다. 즉, 질소산화물(NOx)과의 반응에 필요한 적정 환원제의 양보다 환원제가 과잉 공급되면 과잉 공급된 환원제는 미반응된 채로 SCR 반응기로부터 배출되며, 환원제의 낭비를 초래하게 된다. When the amount of the reducing agent supplied into the SCR reactor is increased, the amount of nitrogen oxides (NO x ) is also reduced proportionally. However, when the amount of the reducing agent exceeds a certain level, the decrease of the nitrogen oxide (NO x ) is stagnated, which means that the amount of the unreacted reducing agent is increased. That is, when the reducing agent is excessively supplied than the amount of the appropriate reducing agent required for the reaction with the nitrogen oxide (NO x ), the excessively supplied reducing agent is discharged unreacted from the SCR reactor, resulting in waste of the reducing agent.

종래의 SCR 장치의 경우, 미리 설정된 일정량의 환원제가 지속적으로 SCR 반응기에 공급하도록 설계되어 있어 환원제가 낭비되는 문제점이 있었으며, 이를 해결하기 위해 본 출원인은 한국특허출원 2013-147577호를 통해 배기가스 내의 질소산화물(NOx)의 양에 따라 환원제를 선택적으로 공급하는 기술을 제시한 바 있다. In the case of the conventional SCR apparatus, a predetermined amount of the reducing agent is designed to continuously supply to the SCR reactor, and thus a reducing agent is wasted. In order to solve this problem, the present applicant has proposed Korean Patent Application No. 2013-147577 A technique of selectively supplying a reducing agent according to the amount of nitrogen oxides (NO x ) has been proposed.

한국특허출원 2013-147577호Korean Patent Application No. 2013-147577

본 발명은 상기와 같은 문제점을 해결하기 위해 안출한 것으로서, 질소산화물(NOx)의 양을 측정하는 지르코니아(ZrO2) 센서의 특성을 이용하여 환원제 공급량을 최적화할 수 있는 SCR 시스템의 환원제 공급량 제어장치를 제공하는데 그 목적이 있다.
SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a reducing agent supply amount control method of an SCR system capable of optimizing a reducing agent supply amount by using characteristics of a zirconia (ZrO 2 ) sensor for measuring the amount of NO x The purpose of the device is to provide.

상기의 목적을 달성하기 위한 본 발명에 따른 SCR 시스템의 환원제 공급량 제어장치는 환원제에 의한 질소산화물의 환원 반응이 진행되는 공간을 제공하는 SCR 반응기와, 상기 SCR 반응기에 환원제를 공급하는 환원제 공급장치와, 상기 SCR 반응기로부터 배출되는 배기가스에 포함되어 있는 질소산화물(NOx)의 양을 검출하는 질소산화물 검출센서 및 상기 환원제 공급장치로부터 SCR 반응기에 공급되는 환원제 공급량 정보 및 상기 질소산화물 검출센서에 의해 측정되는 질소산화물 검출정보를 기반으로 하여, 환원제 공급량에 따른 질소산화물 변화를 체크하며, 환원제 공급량의 제 1 시점 이후 제 2 시점까지 질소산화물이 증가되면 상기 제 1 시점을 변곡점으로 인식하여 환원제 공급장치에 의해 공급되는 환원제 공급량을 제 1 시점의 환원제 공급량으로 제어하는 제어수단을 포함하여 이루어지는 것을 특징으로 한다. In order to accomplish the above object, an apparatus for controlling a reducing agent supply amount of an SCR system according to the present invention includes an SCR reactor for providing a space in which a reduction reaction of nitrogen oxide by a reducing agent proceeds, a reducing agent supply device for supplying a reducing agent to the SCR reactor, A nitrogen oxide detection sensor for detecting the amount of nitrogen oxide (NO x ) contained in the exhaust gas discharged from the SCR reactor, and a reducing agent supply amount information supplied from the reducing agent supply device to the SCR reactor and the nitrogen oxide detection sensor The amount of the reducing agent is monitored based on the detected nitrogen oxide detection information, and if the amount of nitrogen oxide is increased to the second point in time after the first point of time of the amount of the reducing agent, the first point of time is recognized as an inflection point, To the reducing agent supply amount at the first time point It characterized by comprising control means for control.

상기 질소산화물 검출센서는 지르코니아(ZrO2) 센서이며, 상기 지르코니아(ZrO2) 센서는 질소산화물(NOx)을 일산화질소(NO)로 전환시키고 일산화질소(NO)로부터 분해되는 산소 이온의 양을 기반으로 질소산화물(NOx)을 측정함과 함께, 지르코니아(ZrO2) 센서는 암모니아(NH3)를 일산화질소(NO)로 전환시키고 일산화질소(NO)로부터 분해되는 산소 이온의 양을 질소산화물(NOx)로 인식하는 특성을 갖는다.
The nitrogen oxide sensor is a zirconia (ZrO 2) sensor, and the zirconia (ZrO 2) sensor is the amount of oxygen ions decomposed from the conversion of nitrogen oxides (NO x) to nitrogen monoxide (NO) and nitrogen monoxide (NO) (ZrO 2 ) sensor converts ammonia (NH 3 ) into nitrogen monoxide (NO) and the amount of oxygen ions decomposed from nitrogen monoxide (NO) into nitrogen oxide (NO x ) (NO x ).

본 발명에 따른 SCR 시스템의 환원제 공급량 제어장치는 다음과 같은 효과가 있다. The reducing agent supply amount control apparatus of the SCR system according to the present invention has the following effects.

미반응 암모니아(NH3)를 질소산화물로 인식하는 지르코니아(ZrO2) 센서의 특성을 이용하여 환원제 공급량이 증가됨에도 불구하고 질소산화물의 검출량이 증가되는 시점을 변곡점으로 특정하고, 해당 변곡점에서의 환원제 공급량 이상으로 환원제가 공급되는 것을 방지하여 환원제가 낭비되는 것을 방지할 수 있게 된다.
The point of time when the amount of the nitrogen oxide to be detected is increased is specified as an inflection point in spite of the increase of the amount of the reducing agent supplied using the characteristic of the zirconia (ZrO 2 ) sensor which recognizes unreacted ammonia (NH 3 ) as nitrogen oxide, It is possible to prevent the reducing agent from being supplied to the supply amount or more and to prevent the reducing agent from being wasted.

도 1은 본 발명의 일 실시예에 따른 SCR 시스템의 환원제 공급량 제어장치의 구성도.
도 2는 환원제(Urea) 공급량에 따른 SCR 반응기의 질소산화물(NOx) 변화를 나타낸 것.
도 3은 환원제 공급량에 따른 질소산화물 변화 추이 및 변곡점, 제 1 시점 및 제 2 시점을 나타낸 참고도. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a reducing agent supply amount control apparatus of an SCR system according to an embodiment of the present invention; FIG.
FIG. 2 shows the change in nitrogen oxide (NO x ) of the SCR reactor depending on the amount of the reducing agent (Urea) supplied.
3 is a reference view showing a transition of nitrogen oxide and an inflection point, a first point and a second point of time according to the amount of the reducing agent supplied.

본 발명은 SCR 반응기로부터 배출되는 배기가스에 포함되어 있는 질소산화물(NOx)의 변화 추세를 이용하여 SCR 반응기에 공급되는 환원제가 과잉 공급되지 않도록 하는 기술을 제시하며, 본 발명의 기술은 질소산화물(NOx) 검출센서로 지르코니아(ZrO2) 센서를 사용함을 전제한다. The present invention proposes a technique for preventing excessive supply of a reducing agent supplied to an SCR reactor by using a trend of change in nitrogen oxide (NO x ) contained in exhaust gas discharged from an SCR reactor, (ZrO 2 ) sensor is used as the detection sensor (NO x ).

앞서, '발명의 배경이 되는 기술'에서 언급한 바와 같이, SCR 반응기 내에 공급되는 환원제의 공급량이 증가되면 SCR 반응기의 배기가스에 포함되어 있는 질소산화물(NOx)은 감소된다. 이는 환원제로부터 가수분해된 암모니아(NH3)가 SCR 반응기 내에서 질소산화물(NOx)과 반응하기 때문이다. 한편, 질소산화물(NOx)과의 반응에 필요한 적정 환원제의 양보다 환원제가 과잉 공급되면 과잉 공급된 환원제는 미반응된 채로 SCR 반응기로부터 배출된다. As mentioned in the Background of the Invention, when the amount of the reducing agent supplied into the SCR reactor is increased, the amount of NO x contained in the exhaust gas of the SCR reactor is reduced. This is because ammonia (NH 3 ) hydrolyzed from the reducing agent reacts with nitrogen oxides (NO x ) in the SCR reactor. On the other hand, if the reducing agent is excessively supplied than the amount of the appropriate reducing agent necessary for the reaction with the nitrogen oxide (NO x ), the excess supplied reducing agent is discharged unreacted from the SCR reactor.

질소산화물(NOx)의 감소 추세가 정체됨에도 불구하고, 환원제의 공급량이 증가되는 것은 SCR 반응기의 후단에 구비되어 SCR 반응기의 배기가스에 포함되어 있는 질소산화물(NOx)의 양을 측정하는 질소산화물(NOx) 검출센서 즉, 지르코니아(ZrO2) 센서의 특성에 기인한다. 지르코니아(ZrO2) 센서는 전원 인가시 산소 이온(O2-)을 전도하는 특성을 갖고 있으며, 이와 같은 특성 하에 질소산화물(NOx)을 일산화질소(NO)로 전환시키고, 최종적으로 일산화질소(NO)를 질소(N2)와 산소(O2)로 분해하며, 최종 생성된 산소 농도를 통해 질소산화물(NOx)의 농도를 산출하는 방식으로 동작된다(유럽공개특허 EP769,694호 참조).Despite the stagnation of the decrease of nitrogen oxides (NO x ), the increase in the amount of the reducing agent is due to the fact that the amount of nitrogen (NO x ) contained in the exhaust gas of the SCR reactor Oxide (NO x ) detection sensor, that is, the characteristic of zirconia (ZrO 2 ) sensor. The zirconia (ZrO 2 ) sensor has a characteristic of conducting oxygen ions (O 2- ) when the power is applied. Under these characteristics, the nitrogen oxide (NO x ) is converted into nitrogen monoxide (NO) NO) is decomposed into nitrogen (N 2 ) and oxygen (O 2 ), and the concentration of nitrogen oxide (NO x ) is calculated through the finally produced oxygen concentration (see EP-A-679,694) .

그런데, 이와 같은 지르코니아(ZrO2) 센서는 질소산화물(NOx) 이외에 암모니아(NH3) 역시 일산화질소(NO)로 전환시키는 특성을 갖고 있다. 즉, 질소산화물(NOx)과 반응하지 않은 미반응 암모니아(NH3)는 일산화질소(NO)로 전환되고, 암모니아(NH3)로부터 전환된 일산화질소(NO)가 지르코니아(ZrO2) 센서에 의해 질소산화물(NOx)로 인식된다. 이와 같이, 환원제의 가수분해에 의해 생성된 암모니아(NH3)가 질소산화물(NOx)과 반응하지 않는 경우 지르코니아(ZrO2) 센서에 의해 질소산화물(NOx)로 인식됨에 따라, SCR 반응기의 배기가스에 실제 포함되어 있는 질소산화물(NOx)의 양보다 많은 양의 질소산화물(NOx)이 검출되는 것이다. However, such a zirconia (ZrO 2 ) sensor has a characteristic of converting ammonia (NH 3 ) into nitrogen monoxide (NO) in addition to nitrogen oxide (NO x ). That is, the non-reacted ammonia (NH 3) is converted into nitrogen monoxide (NO), ammonia (NH 3) a nitrogen monoxide (NO) is zirconia (ZrO 2) sensor switch from a non-reaction with the nitrogen oxide (NO x) (NO x ). ≪ / RTI > In this way, the, SCR reactor in accordance with recognized by the ammonia (NH 3) is a nitrogen oxide (NO x) and does not react with the zirconia (ZrO 2) the nitrogen oxide (NO x) by means of a sensor produced by the hydrolysis of a reducing agent (NO x ) greater than the amount of nitrogen oxide (NO x ) actually contained in the exhaust gas is detected.

도 2는 환원제(Urea) 공급량에 따른 SCR 반응기의 질소산화물(NOx) 변화를 나타낸 것이다. 도 2에서 빨간색 그래프는 퓨리에변환 적외선분광기(FTIR, Fourier Transform Infrared Spectrometer)를 이용하여 SCR 반응기의 배기가스에 포함되어 있는 질소산화물(NOx)의 양을 측정한 값이고, 파란색 그래프는 지르코니아(ZrO2) 센서를 이용하여 SCR 반응기의 배기가스에 포함되어 있는 질소산화물(NOx)의 양을 측정한 값이다. 퓨리에변환 적외선분광기(FTIR)로 측정한 결과는 SCR 반응기로부터 배출되는 기체를 적외선 분광방식으로 측정한 것으로서 실제 결과에 근접한 결과이다. 2 shows the change in nitrogen oxide (NO x ) of the SCR reactor depending on the amount of the reducing agent (Urea) supplied. 2, the red graph is a value obtained by measuring the amount of nitrogen oxide (NO x ) contained in the exhaust gas of the SCR reactor by using a Fourier transform infrared spectrometer (FTIR), and the blue graph is a value obtained by measuring the amount of zirconia 2 ) The amount of nitrogen oxide (NO x ) contained in the exhaust gas of the SCR reactor was measured using a sensor. The results of Fourier transform infrared spectroscopy (FTIR) were obtained by measuring the gas emitted from the SCR reactor by infrared spectroscopy.

FTIR 결과를 참조하면, 환원제 공급량의 증가에 비례하여 SCR 반응기의 배기가스로부터 검출되는 질소산화물(NOx)의 양이 감소됨을 알 수 있으며, 환원제 공급량이 일정 시점 이상인 경우에는 질소산화물(NOx)의 양이 더 이상 감소하지 않고 일정 수준을 유지함을 확인할 수 있다. Referring to FTIR results, and in proportion to an increase in the reducing agent supply amount, the amount of nitrogen oxide (NO x) is detected from the exhaust gas in the SCR reactor can be seen to decrease, if the reducing agent supply amount more than a certain point, the nitrogen oxide (NO x) Of the total number of workers is not decreased any more and it maintains a certain level.

한편, 지르코니아(ZrO2) 센서의 결과에서는 FTIR 결과와 마찬가지로 환원제 공급량에 비례하여 질소산화물(NOx)의 양이 감소하나, 특정 시점 이후에서는 환원제 공급량이 증가됨에도 불구하고 검출되는 질소산화물(NOx)의 양이 오히려 증가됨을 확인할 수 있다. 특정 시점 이후, 환원제 공급량이 증가됨에도 불구하고 검출되는 질소산화물(NOx)의 양이 증가되는 것은 상술한 바와 같은 지르코니아(ZrO2) 센서 특성 때문이다. 즉, 환원제가 과잉 공급됨으로 인해 미반응 암모니아(NH3)가 존재하게 되고, 미반응 암모니아(NH3)가 지르코니아(ZrO2) 센서에 의해 일산화질소(NO)로 전환됨과 함께 질소산화물(NOx)로 인식되어 질소산화물(NOx)의 양이 증가되는 것으로 측정되는 것이다. On the other hand, zirconia (ZrO 2) in the result of one sensor as in the FTIR results in proportion to the reducing agent supply amount reduces the amount of nitrogen oxides (NO x), the later point in time the nitrogen to which even though the reducing agent supply amount is increased, and detection oxide (NO x ) Is increased. It is because of the characteristic of the zirconia (ZrO 2 ) sensor as described above that the amount of nitrogen oxide (NO x ) detected after a specific point in time is increased despite the increase of the reducing agent supply amount. That is, the reducing agent is excessive due doemeuro supply and the presence of unreacted ammonia (NH 3), the unreacted ammonia (NH 3) is zirconia (ZrO 2) oxides of nitrogen together and converted into nitrogen monoxide (NO) by the sensor (NO x ), And the amount of nitrogen oxide (NO x ) is increased.

본 발명은 이와 같은 지르코니아(ZrO2) 센서의 질소산화물(NOx) 검출 특성을 이용한다. 즉, 본 발명은 미반응 암모니아(NH3)를 질소산화물(NOx)로 인식하는 지르코니아(ZrO2) 센서의 특성을 이용한다. The present invention utilizes the nitrogen oxide (NO x ) detection characteristic of such a zirconia (ZrO 2 ) sensor. That is, the present invention utilizes the characteristics of a zirconia (ZrO 2 ) sensor that recognizes unreacted ammonia (NH 3 ) as nitrogen oxides (NO x ).

이하, 도면을 참조하여 본 발명의 일 실시예에 따른 SCR 시스템의 환원제 공급량 제어장치를 상세히 설명하기로 한다. Hereinafter, a reducing agent supply amount control apparatus for an SCR system according to an embodiment of the present invention will be described in detail with reference to the drawings.

도 1을 참조하면, 본 발명의 일 실시예에 따른 SCR 시스템의 환원제 공급량 제어장치는 SCR 반응기, 환원제 공급장치(120), 질소산화물 검출센서(130) 및 제어수단(140)을 포함하여 구성된다. Referring to FIG. 1, the reducing agent supply amount control apparatus of the SCR system according to an embodiment of the present invention includes an SCR reactor, a reducing agent supply unit 120, a nitrogen oxide detection sensor 130, and a control unit 140 .

상기 SCR 반응기(110)는 환원제에 의한 질소산화물의 환원 반응이 진행되는 공간을 제공한다. 환원제는 요소수일 수 있으며, 요소수는 SCR 반응기(110) 내에서 가수분해되어 암모니아(NH3)를 생성하며, 생성된 암모니아(NH3)는 질소산화물(NOx)과 반응하고 환원 반응에 의해 질소산화물(NOx)은 질소(N2)와 수증기로 환원된다. 상기 환원제 공급장치(120)는 상기 SCR 반응기(110) 내에 우레아(urea) 등의 환원제를 공급하는 역할을 한다. The SCR reactor 110 provides a space where the reduction reaction of nitrogen oxides by the reducing agent proceeds. The reducing agent may be a urea water and the urea water is hydrolyzed in the SCR reactor 110 to produce ammonia (NH 3 ). The generated ammonia (NH 3 ) reacts with nitrogen oxides (NO x ) Nitrogen oxides (NO x ) are reduced to nitrogen (N 2 ) and water vapor. The reducing agent supply unit 120 serves to supply a reducing agent such as urea into the SCR reactor 110.

상기 질소산화물 검출센서(130)는 상기 SCR 반응기(110)로부터 배출되는 배기가스에 포함되어 있는 질소산화물(NOx)의 양을 검출하는 역할을 한다. 상기 질소산화물 검출센서(130)는 공지의 지르코니아(ZrO2) 센서가 적용된다. 상기 지르코니아(ZrO2) 센서는 질소산화물(NOx)을 일산화질소(NO)로 전환시키고 일산화질소(NO)로부터 분해되는 산소 이온의 양을 기반으로 질소산화물(NOx)을 측정한다. 또한, 지르코니아(ZrO2) 센서는 전술한 바와 같이 암모니아(NH3)를 일산화질소(NO)로 전환시키고 일산화질소(NO)로부터 분해되는 산소 이온의 양을 질소산화물(NOx)로 인식하는 특성을 갖는다. The nitrogen oxide detection sensor 130 detects the amount of nitrogen oxide (NO x ) contained in the exhaust gas discharged from the SCR reactor 110. A known zirconia (ZrO 2 ) sensor is applied to the nitrogen oxide detection sensor 130. The zirconia (ZrO 2 ) sensor converts nitrogen oxide (NO x ) to nitrogen monoxide (NO) and measures nitrogen oxide (NO x ) based on the amount of oxygen ions decomposed from nitrogen monoxide (NO). The zirconia (ZrO 2 ) sensor has a characteristic of converting ammonia (NH 3 ) into nitrogen monoxide (NO) and recognizing the amount of oxygen ions decomposed from nitrogen monoxide (NO) as nitrogen oxide (NO x ) Respectively.

상기 제어수단(140)은 상기 환원제 공급장치(120)로부터 SCR 반응기(110)에 공급되는 환원제 공급량 정보 및 상기 질소산화물 검출센서(130)에 의해 측정되는 질소산화물 검출정보를 기반으로 하여, 환원제 공급량에 따른 질소산화물 변화를 체크하며, 환원제 공급량의 제 1 시점 이후 제 2 시점까지 질소산화물이 증가되면 상기 제 1 시점을 변곡점으로 인식하여 환원제 공급장치(120)에 의해 공급되는 환원제 공급량을 제 1 시점의 환원제 공급량으로 제어하는 역할을 한다. Based on the reducing agent supply amount information supplied from the reducing agent supply device 120 to the SCR reactor 110 and the nitrogen oxide detection information measured by the nitrogen oxide detection sensor 130, the control means 140 controls the supply amount of the reducing agent The amount of reducing agent supplied from the reducing agent supplying device 120 is determined as the inflection point at the first point in time when the nitrogen oxide is increased to the second point in time after the first point of time of the reducing agent supply amount, Of the amount of reducing agent supplied.

상기 제어수단(140)에 의해 체크되는 환원제 공급량에 따른 질소산화물의 추이는 다음과 같이 정의된다. 최소량의 환원제가 공급되는 시점을 최초 시점이라 하면, 최초 시점에서 제 1 시점까지는 환원제 공급량의 증가에 따라 질소산화물의 검출량은 감소하며, 변곡점인 제 1 시점에서 제 2 시점까지는 환원제 공급량은 증가하고 질소산화물의 검출량 또한 증가한다(도 3 참조). 제 1 시점 즉, 변곡점을 기준으로 질소산화물 검출량의 감소 추세가 증가 추세로 전환하는 것은 전술한 바와 같은 지르코니아(ZrO2) 센서의 미반응 암모니아(NH3)의 질소산화물로의 인식 때문이다. The transition of the nitrogen oxide according to the amount of the reducing agent to be checked by the control means 140 is defined as follows. From the initial point of time to the first point of time, the amount of reducing agent decreases as the amount of reducing agent supplied increases, and the amount of reducing agent increases from the first point of time to the second point of inflection, The detection amount of the oxide also increases (see Fig. 3). The first point of view, that is, the tendency of decreasing the detection amount of nitrogen oxides based on the inflection point, is shifting to an increasing trend because of the recognition of unreacted ammonia (NH 3 ) of the zirconia (ZrO 2 ) sensor as described above as nitrogen oxides.

제 1 시점을 기준으로 질소산화물 검출량이 증가 추세로 전환되더라도 해당 추가 추세가 지르코니아(ZrO2) 센서의 미반응 암모니아(NH3)의 질소산화물로의 인식 때문이 아닌 일시적인 현상일 수도 있는 점을 고려하여 제 2 시점까지 환원제 공급량을 늘리고 제 2 시점까지 질소산화물 검출량의 증가 추세가 지속되는지 확인할 필요가 있다. 제 2 시점의 환원제 공급량은 임의에 따라 설정할 수 있다. Even if the NOx detection amount is converted to an increasing trend based on the first time point, it is considered that the additional trend may be a temporary phenomenon rather than a recognition of the unreacted ammonia (NH 3 ) of the zirconia (ZrO 2 ) sensor as nitrogen oxides It is necessary to increase the amount of the reducing agent to the second point of time and to confirm whether the increase amount of the nitrogen oxide detection amount continues until the second point in time. The amount of the reducing agent supplied at the second time point can be set arbitrarily.

이와 같은 구성 하에, 환원제 공급량에 따른 질소산화물 변화 추이에서 제 1 시점 이후 제 2 시점까지 질소산화물이 증가되면 상기 제어수단(140)은 상기 제 1 시점을 변곡점으로 인식함과 함께 환원제 공급장치(120)에 의해 공급되는 환원제 공급량을 제 1 시점의 환원제 공급량으로 제어하여 환원제의 과잉 공급을 방지할 수 있게 된다.
When the nitrogen oxide is increased from the first point of view to the second point of time in the change of the nitrogen oxide depending on the amount of the reducing agent supplied, the control unit 140 recognizes the first point of time as an inflection point, ) Is controlled to be the amount of the reducing agent supplied at the first time point, thereby preventing the excessive supply of the reducing agent.

110 : SCR 반응기 120 : 환원제 공급장치
130 : 질소산화물 검출센서 140 : 제어수단110: SCR reactor 120: Reducing agent supply device
130: nitrogen oxide detection sensor 140: control means

Claims (2)

환원제에 의한 질소산화물의 환원 반응이 진행되는 공간을 제공하는 SCR 반응기;
상기 SCR 반응기에 환원제를 공급하는 환원제 공급장치;
상기 SCR 반응기로부터 배출되는 배기가스에 포함되어 있는 질소산화물(NOx)의 양을 검출하는 질소산화물 검출센서; 및
상기 환원제 공급장치로부터 SCR 반응기에 공급되는 환원제 공급량 정보 및 상기 질소산화물 검출센서에 의해 측정되는 질소산화물 검출정보를 기반으로 하여, 환원제 공급량에 따른 질소산화물 변화를 체크하며, 환원제 공급량의 제 1 시점 이후 제 2 시점까지 질소산화물이 증가되면 상기 제 1 시점을 변곡점으로 인식하여 환원제 공급장치에 의해 공급되는 환원제 공급량을 제 1 시점의 환원제 공급량으로 제어하는 제어수단을 포함하여 이루어지는 것을 특징으로 하는 SCR 시스템의 환원제 공급량 제어장치.
An SCR reactor for providing a space in which the reduction reaction of nitrogen oxide by the reducing agent proceeds;
A reducing agent supply device for supplying a reducing agent to the SCR reactor;
A nitrogen oxide detection sensor for detecting the amount of nitrogen oxide (NO x ) contained in the exhaust gas discharged from the SCR reactor; And
The nitrogen oxide change according to the reducing agent supply amount is checked based on the reducing agent supply amount information supplied from the reducing agent supply device to the SCR reactor and the nitrogen oxide detection information measured by the nitrogen oxide detection sensor, And control means for recognizing the first time point as an inflection point and controlling the supply amount of the reducing agent supplied by the reducing agent supply device to the supply amount of the reducing agent at the first point of time when the nitrogen oxide is increased to the second point in time A reducing agent supply amount control device.
제 1 항에 있어서, 상기 질소산화물 검출센서는 지르코니아(ZrO2) 센서이며,
상기 지르코니아(ZrO2) 센서는 질소산화물(NOx)을 일산화질소(NO)로 전환시키고 일산화질소(NO)로부터 분해되는 산소 이온의 양을 기반으로 질소산화물(NOx)을 측정함과 함께,
지르코니아(ZrO2) 센서는 암모니아(NH3)를 일산화질소(NO)로 전환시키고 일산화질소(NO)로부터 분해되는 산소 이온의 양을 질소산화물(NOx)로 인식하는 특성을 갖는 것을 특징으로 하는 SCR 시스템의 환원제 공급량 제어장치. The method of claim 1, wherein the nitrogen oxide detection sensor is a zirconia (ZrO 2 ) sensor,
The zirconia (ZrO 2 ) sensor converts nitrogen oxide (NO x ) into nitrogen monoxide (NO) and measures nitrogen oxide (NO x ) based on the amount of oxygen ions decomposed from nitrogen monoxide (NO)
The zirconia (ZrO 2 ) sensor has a characteristic of converting ammonia (NH 3 ) into nitrogen monoxide (NO) and recognizing the amount of oxygen ions decomposed from nitrogen monoxide (NO) as nitrogen oxide (NO x ) Reducing agent feed rate control device in SCR system.
KR1020140168008A 2014-11-28 2014-11-28 Apparatus for controlling supplying of reducing agent in selective catalytic reduction system KR20160064422A (en)

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JP4854122B2 (en) * 2001-03-16 2012-01-18 東京瓦斯株式会社 Reducing agent addition amount control method
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