다종의 레이저 H₂O 광흡수 파장을 이용한 정밀 온도계측 및 광 경로 내 온도 구간 분석에 관한 연구

유미연(Miyeon Yoo),소성현(Sunghyun So),박지연(Jiyeon Park),김대해(Daehae Kim),박대근(Daegeun Park),이창엽(Changyeop Lee) 한국에너지기후변화학회 2019 에너지기후변화학회지 Vol.14 No.2

Temperature is a basic monitoring element for combustion efficiency improvement and pollutant gas reduction in a large combustion system. but it is very difficult that measuring temperature precisely and predicting temperature distribution. For that reason, the on about precise temperature measurement has been continuing. Among various methods of measuring temperature, TDLAS(Tunable Diode Laser Absorption Spectroscopy), which is an optical method using a laser, is attracting attention. TDLAS method is good to use due to contactless measurement, fast response time, high precision and good durability in larger combustion system. TDLAS method can measure the temperature as analyzing of optical absorption signals of water vapor using a DFB(Distributed feedback) laser. Water vapor has optically strong absorption signals on 1.3 ㎛ to 1.4 ㎛, and it can be used in a large combustion system which requires temperature division analysis method. In this paper, various laser wavelengths and absorption signals were used to attempt temperature division analysis.

가스의 광 흡수 특성 분석을 통한 대형 연소시스템 내 실시간 온도 및 농도 계측에 관한 실증 연구

박지연,소성현,박대근,류창국,이창엽,유미연 한국가스학회 2020 한국가스학회지 Vol.24 No.5

It is practically difficult to accurately measure the temperature and concentrationof a large combustion systems at industrial sites in real time. Temperature measurement usingthermocouple, which are mainly used, is a point-measuring method that is less accurate andless reliable to analyze the wide area range of inner combustion system, and has limitationsto internal accessibility. In terms of concentration analysis, most measurement methods usesampling method, which are limited by the difficulty of real-time measurement. As a way toovercome these limitations, laser-based measurement methods have been developedcontinuously. Laser-based measurement are line-average measurement methods with high rep resentation and precision, which are beneficial for the application of large combustion systems. In this study the temperature and concentration were measured in real time by water vaporand oxygen generated during combustion using Tunable Diode Laser Absorption Spectroscopy(TDLAS). The results showed that the average temperature inside the combustion system was1330°C and the mean oxygen concentration was 3.3 %, which showed similar tendency withplant monitoring data. 산업현장의 대형 연소시스템 내부의 온도 및 농도를 실시간으로 정밀하게 계측하는 일은 그 규모 및 환경 조건으로 인해 사실상 어렵다. 현재 주로 사용되고 있는 열전대를 이용한 온도 계측은 점 측정 방식으로 대형 연소시스템내부 광역 범위의 온도 분석에 적용하기에는 정밀성과 신뢰성이 낮으며, 접근성에 한계가 있다. 농도 분석 측면에서 대부분의 계측 방법은 샘플링 방식으로 실시간 측정이 어렵고 대표성에 한계가 있다. 이러한 한계점을 극복하기위한 방법으로, 레이저를 이용한 측정법이 지속적으로 개발되고 있다. 레이저 기반 측정법들은 선 평균 측정 방식으로 대표성과 정밀도가 뛰어나 대형 연소시스템 적용에 유리하다. 본 연구에서는 파장 가변형 레이저 흡수 분광법(Tunable Diode Laser Absorption Spectroscopy, TDLAS)을 통해 연소 시에 발생하는 수증기와 산소를 이용하여 실시간으로 온도 및 농도를 측정하였다. 측정 결과 연소시스템 내부 평균 온도는 1330℃, 평균 산소 농도는 3.3 %로발전소 데이터와 비교하였을 때 유사한 경향성의 측정값을 얻었다.

Area-based velocimetry using TDLAS for low-speed flow

정시온,Hanseul Shim,Gyeongrok Kim,박기수 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.8

This study presents an absorption-area-based method for the measurement of gas flow velocity using diode laser absorption spectroscopy. In the proposed method, the gas flow velocity is determined using the area difference between the absorption lines. To verify the proposed method, flow velocity measurements are conducted for test conditions with a velocity range of 5-30 m/s in a low-speed wind tunnel, and the results are compared with those of the conventional method using the Doppler-shifted peak. Oxygen in the air is selected as the target gas. By comparing the flow velocity measurement results of the conventional method and the proposed area-based method, it is confirmed that the measurement precision is improved when the proposed area-based method is used. Moreover, the measurement accuracy of the proposed area-based method is significantly improved at a relatively low-speed range of 5-10 m/s compared to the conventional method.

파장 변조 기법을 이용한 연소배기 가스의 계측

김동혁(Dong-Hyuck Kim),김세원(Se-Won Kim),신명철(Myung-Chul Shin),김용모(Yong-Mo Kim) 한국연소학회 2006 KOSCOSYMPOSIUM논문집 Vol.- No.-

This work forcus on the development of gas sensor that measure the concentrations of exhaust gas using diode laser. Each diode laser for exhaust gas measurement is set to work at near-IR using both DA and WMS methods. Also use of fiber-coupled optical elements makes such a sensor rugged and easy to align. On-line data acquisition and processing can be performed with a PC running LabVIEW software, and absorption signals are measured simultaneously by multiplexing method. Finally, It were experimentally compared WMS (Wavelength Modulation Spectroscopy) with DA (Direct Absorption) for the accuracy.

연소배기 가스의 계측을 위한 다이오드 레이저 센서

신명철(Myung Chul Shin),김세원(Se Won Kim),김동혁(Dong Hyuck Kim) 한국연소학회 2006 한국연소학회지 Vol.11 No.3

This work forcus on the development of gas sensor that measure the concentrations of exhaust gas using diode laser. Each diode laser for exhaust gas measurement is set to work at near-IR using both DA and WMS methods. Also use of fiber-coupled optical elements makes such a sensor rugged and easy to align. The results showed that gas concentrations of O₂, CO, CO₂, NO are accurately measured within ±2% error. The application of WMS method increased the beam intensity 2-3 times higher than DA method. It were experimentally compared WMS (Wavelength Modulation Spectroscopy) with DA (Direct Absorption) for the accuracy.

근적외선 영역의 흡수 분광법을 이용한 불균일 온도 분포 조건에서의 정밀 산소 농도 측정에 관한 연구

소성현(Sunghyun So),유미연(Miyeon Yoo),맹새롬(Saerom Maeng),김대해(Daehae Kim),박호영(Hoyoung Park),이창엽(Changyeop Lee) 한국에너지기후변화학회 2018 에너지기후변화학회지 Vol.13 No.1

This study describes a measurement of oxygen concentration at Non-uniform high temperature region. Accurate measuring of internal temperatures and oxygen concentrations in high-temperature gases is important for improving energy efficiency of a combustion system and reduction of pollutant. However, it is not easy to measure the temperature inside combustion boiler by T/C(Thermocouple). because of its internal temperature and solid particles. And to overcome the reliability problem of measured temperature in huge combustion system such as power plant boiler, it is necessary to measure the line average temperature like as TDLAS method. TDLAS is a very attractive analysis technique for measuring the temperature and concentration of certain species in a gaseous mixture inside the combustion system. When a gas concentration is measured by TDLAS, Line-strength which is one of the important physical parameter becomes a indispensable value. Because the line-strength varies according to temperature change, accurate temperature values are needed to measure a gas concentration precisely. In this study, The temperature was measured via the strong H₂O absorption signals with a four near infrared diode lasers. And the oxygen concentration was measured using a visible diode laser in addition to applying exact line averaged temperature measured by H₂O absorption signals.

광흡수 신호가 완전 중첩된 조건에서 내재 흡수 면적 도출을 통한 2종 가스 농도 분석에 관한 연구

유미연(Miyeon Yoo),맹새롬(Saerom Maeng),소성현(Sunghyun So),이창엽(Changyeop Lee) 한국에너지기후변화학회 2016 에너지기후변화학회지 Vol.11 No.1

In a huge combustion system such as powerplant boiler, it is important to measure gas concentrations and internal temperatures precisely. The gas concentrations and temperatures is are the indispensable physical to operate and maintain the combustion system efficiently and to design a new combustion system. And the concentration of a combustion gas like CO₂ and CO can be a most important factor to indicate the energy efficiency of a large combustion system. TDLAS (Tunable Diode Laser Absorption Spectroscopy) method can be used to measure the gas concentration, temperature or speed of a gas with a diode laser. Absorption spectroscopy measurement measuring system with DFB(Distributed feed-back) diode laser can realize non-contacting and real-time measurement and semipermanent longevity. In this study, a TDLAS-based gas concentration measurement method was suggested to analyze the concentration of two gas species, CO₂ and CO, with a non-independent absorption signal.

다이오드 레이저를 이용한 연소 배기가스의 농도 계측 기법 개발

김동혁(Dong-Hyuck Kim),신명철(Myung-Chul Shin),김세원(Se-Won Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11

This work forcus on the development of gas measurement sensor about harmful exhaust gas using diode laser in the combustion environment. A diode laser sensor has been applied to monitor the combustion gases in combustion environment with absorption spectroscopy and fast extraction-sampling techniques. Species concentrations above combustion flow were determined from measured absorption in a fast-flow multipass absortion cell containing probe-sampled combustion gases. Also, To exchange the number density to concentrations, we need to the experimental equation . we obtain the equation and perform the calibration about each gas. In this paper, will compare accuracy and standard deviation between diode laser sensor and commercial gas sensor for CO₂ concentration in the combustion environment.

TDLAS를 이용한 고온로 내 산소 농도 측정에 관한 연구

소성현(Sunghyun So),유미연(Miyeon Yoo),맹새롬(Saerom Maeng),이창엽(ChangYeop Lee) 한국에너지기후변화학회 2017 에너지기후변화학회지 Vol.12 No.2

The use of a tunable diode laser absorption sensor(TDLAS) for concentration measurement of oxygen in a high temperature furnace is presented. The concentration of oxygen was chosen as the target species to increase the energy efficiency and to reduce the pollutants. The sensor utilizes diode laser of having the visible absorption band of oxygen near 13142.5 cm<SUP>-1</SUP>. And both scanned-wavelength direct absorption spectroscopy and wavelength modulation spectroscopy with second-harmonic detection (WMS-2f ) techniques were used to measure oxygen concentration precisely. The results in this paper show that the advantages of wavelength modulation spectroscopy method over direct absorption spectroscopy appear in diagnosing the high temperature environment in which the measuring distance is short.

파장가변형 레이저 흡수 분광법을 이용한 수소 농도 분석

박지연,이승룡,정낙원,류창국,유미연,이창엽 한국에너지기후변화학회 2022 에너지기후변화학회지 Vol.17 No.2

Carbon neutrality has been declared to reduce carbon dioxide, which causes global warming, and interestin clean energy that can replace fossil fuels have been increasing significantly. As interest in hydrogen energy increases,research on hydrogen production and measurement is also being actively conducted. Currently, hydrogen is also usedin petrochemical, oil refining, and semiconductor industries, but it is difficult to accurately measure the concentration ofhydrogen gas in various gas mixtures in the process. The generally used hydrogen measurement method is gaschromatography (GC), which has disadvantages in that the measurement speed is slow and the equipment price isexpensive. In addition, various hydrogen sensors are commercialized to detect hydrogen leakage. However, mostcommercial hydrogen measurement sensors have the disadvantage of being difficult to use under reactive, corrosive gasor high dust conditions and have low precision. In this study, Tunable Diode Laser Absorption Spectroscopy (TDLAS) hasbeen used as a method of measuring the hydrogen concentration. The TDLAS method can measure the hydrogenconcentration in real time even under various gas mixing conditions. Hydrogen concentration analysis was performedusing a 2.12 μm near-infrared laser using not only direct absorption spectroscopy (DAS) but also wavelength modulationspectroscopy (WMS), and the measured limits of the two methods were compared with various distance andconcentration conditions.