Applications of laser diagnostics to thermal power plants and engines

• Published in: Applied thermal engineering 2014-12, Vol.73 (2), p.1453-1464
• Main Authors: Deguchi, Y., Kamimoto, T., Wang, Z.Z., Yan, J.J., Liu, J.P., Watanabe, H., Kurose, R.
• Format: Article
• Language: English
• Subjects: Applied sciences; Coal; Computed tomography-tunable diode laser absorption spectroscopy; Energy; Energy. Thermal use of fuels; Engine; Engines; Engines and turbines; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Exhaust; Fly ash; Heat transfer; Installations for energy generation and conversion: thermal and electrical energy; Laser-induced breakdown spectroscopy; Lasers; Low pressure; Power plants; Temperature and concentration measurement; Theoretical studies. Data and constants. Metering; Thermal power plant; Thermal power plants; Thermoelectricity; Time-of-flight mass spectrometry
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2014.05.063

The demands for lowering the burdens on the environment will continue to grow steadily. It is important to monitor controlling factors in order to improve the operation of industrial thermal systems. In engines, exhaust gas temperature and concentration distributions are important factors in nitrogen oxides (NOx), total hydrocarbon (THC) and particulate matter (PM) emissions. Coal and fly ash contents are parameters which can be used for the control of coal-fired thermal power plants. Monitoring of heavy metals such as Hg is also important for pollution control. In this study, the improved laser measurement techniques using computed tomography-tunable diode laser absorption spectroscopy (CT-TDLAS), low pressure laser-induced breakdown spectroscopy (LIBS), and laser breakdown time-of-flight mass spectrometry (LB-TOFMS) have been developed and applied to measure 2D temperature and species concentrations in engine exhausts, coal and fly ash contents, and trace species measurement. The 2D temperature and NH3 concentration distributions in engine exhausts were successfully measured using CT-TDLAS. The elemental contents of size-segregated particles were measured and the signal stability increased using LIBS with the temperature correction method. The detection limit of trace species measurement was enhanced using low pressure LIBS and LB-TOFMS. The detection limit of Hg can be enhanced to 3.5 ppb when employing N2 as the buffer gas using low pressure LIBS. Hg detection limit was about 0.82 ppb using 35 ps LB-TOFMS. Compared to conventional measurement methods laser diagnostics has high sensitivity, high response and non-contact features for actual industrial systems. With these engineering developments, transient phenomena such as start-ups in thermal systems can be evaluated to improve the efficiency of these thermal processes. •Applicability of newly developed laser diagnostics was demonstrated for the improvement of thermal power plants and engines.•Time resolved 2D temperature and NH3 distributions were measured in engine exhausts using CT-TDLAS.•The measurement method of fly ash contents was developed using LIBS for the thermal power plant application.•The sensitive trace species measurement method was developed using low pressure LIBS and LB-TOFMS.