PCBs (polychlorinated biphenyls) are a type of chlorinated aromatic hydrocarbons widely used in condensers and other applications prior to 1970, but now recognized as serious environmental pollutants. "Law Concerning Extraordinary Measures for Promotion of Proper Management of Polychlorinated Biphenyl Waste", which came into effect on July 15,2001, made PCBs disposal mandatory, and many companies are thus engaged in research and development work on PCBs disposal and processing. For protection from PCBs it is necessary to monitor their concentration quite rapidly. But the conventional methods require extensive analytical time (several days per sample) and are not suitable for the above requirement. The objective of the research reported here was to develop the Laser ionization time of flight mass spectrometry (LI-TOFMS) capable of monitoring PCBs within 1 minute. The achievable PCBs sensitivity for real-time (1 minute) measurement was found to be in the ppbV range (0.01 mg/Nm^3) by comparison with the conventional gas sampling / GS-MS (gas chromatograph-mass spectrometry) method. For PCBs, a satisfactory proportional relationship was confirmed between laser-based and conventional results. We examined the exhaust gas measurement using the PCB monitoring system installed in the PCB treatment plant (hydrothermal decomposition). Accordingly, this method implies a useful method for the on-line monitoring of PCBs. In the future we will pursue practical application in the form of a safety management-monitoring device for environmental monitoring.
Two dimensional (2D) temperature and concentration distribution is related to the combustion structure, the combustor efficiency in engines, burners, gas turbines and so on. Recently, tunable diode laser absorption spectroscopy (TDLAS) as a multi-species measurement technique with high sensitivity and high response has been developed and applied to industrial process monitoring and control technologies in combustion environments. With these engineering developments, transient phenomena such as start-ups and load changes in engines have been gradually elucidated in various conditions. This paper discusses a study of the fast response 2D temperature distribution measurement method based on the combination of TDLAS and Computed Tomographic (CT) reconstruction using absorption spectra of water vapor at 1388nm. The computed tomography tunable diode laser absorption spectroscopy (CTTDLAS) method was appliedtoengine exhausts for 2D temperature distribution measurements. The measured 2D temperature showed better characteristics compared with the temperature measured by a thermocouple. Theoretical H2O absorption spectra in the 1388 nm near-infrared region calculated by the revised HITRAN database were used for temperature measurement. For accurate measurement of temperature in combustion gases, the spectroscopic databases were modified using experimentally measured spectral parameters that are not found in the databases. Accuracy of temperature measurement using TDLAS have also been discussed to demonstrate its applicability to various types of combustor.
The transient 3-dimensional temperature distribution within the gas flame during line heating is measured in detail by a high performance L. I. F. measurement system. It has been found that the relative distribution of gas temperature around the torch is almost the same as that in spot heating. It has also been found that this relative distribution is almost unchanged regardless of the temperature increase in the steel plate. Thease results lead us to a new hypothesis that the relative distributions of gas temperature and local heat transfer coefficient around the torch remain unchanged and they are almost the same as those in spot heating during line heating process. A new method of heat input estimation for line heating process based on this hypothesis has been propounded.
In a sodium-cooled fast reactor (SFR), liquid sodium is used as a heat transfer fluid because of its excellent heat transport capability. On the other hand, it has strong chemical reactivity with water vapor. One of the design basis accidents of the SFR is the water leakage into the liquid sodium flow by a breach of heat transfer tubes in a steam generator. Therefore the study on sodium-water chemical reactions is of paramount importance for safety reasons. This study aims to clarify the sodium-water reaction mechanisms using laser diagnostics. The sodium-water counter-flow reactions were measured using laser diagnostics such as laser induced fluorescence, CARS, Raman scattering and photo-fragmentation. The measurement results show that the sodium-water reaction proceeds mainly by the reaction Na + H2O → NaOH + H and the main product is NaOH in this reaction. Its forward and backward reaction rates tend to balance with each other and the whole reaction rate reduces as temperature increases.
A collinear long-short double-pulse laser induced breakdown spectroscopy (LS-DP-LIBS) is employed to detect the underwater metal samples. The emission spectra, time-resolved signal, plasma images and sound characteristics of plasma shockwave are experimentally investigated in this work. The results show that the underwater signal of Al, Cu and Fe spectral lines are significantly improved by collinear LS-DP-LIBS with inter-pulse delay of 35 us. The mechanism of the signal improvement is considered to be the pre irradiation effect of long pulse laser beam. In the collinear LS-DP-LIBS method, the long pulse firstly generates a cavitation bubble in water and provides the gaseous environment. Then the short pulse generates the plasma from sample surface. The present experiments show that the collinear LS-DP-LIBS method has acquired significantly signal improvement in underwater measurement of metal samples. This new method has great potential in deep-sea exploration using LIBS.
Although the time-space mechanism of NOx formation in diesel injection combustion in high temperature and pressure has conventionally been pursued by the sampling method and so forth (1) , the cause-effect relationship on its formation factors still remains to be more accurately clarified. In our present research, NO, OH and soot in diesel fuel flames from a single injection in high temperature and pressure were measured using a motoring compressed injection test system by applying laser induced fluorescence (LIF) (2)(3)(4)(5)(6) and laser induced incandescence (LU) (6)(7) , both of which can provide unperturbed measurements necessary for clarifying formation characteristics of harmful exhaust substances from diesel fuel flames in high pressure.
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