The hydrogen treatment system has been developed in order to prevent the overpressure of the primary containment vessel (PCV) caused by a large amount of hydrogen generated by the metal-water reaction in severe accidents (SAs) of Light Water Reactor. In previous studies, we evaluated the hydrogen treatment rate using a couple of metal oxides, and confirmed that MnO2, CuO, and Co3O4 were effective for the hydrogen oxidation under the oxygen-free condition, then we selected them as reactants[1]. Although the reactants were granulated with a diameter of 2 mm for application to the system, the hydrogen treatment rate has not been scarcely evaluated for the granulated MnO2 which is expected to treat the hydrogen around 120 °C [2]. Thus, we made the diameter of the granulated MnO2 smaller, and found that the hydrogen treatment was occurred by the granulated MnO2 with a diameter below 1.0 mm. The granules with a diameter below 1.0 mm were also acceptable for the system from the point of view of decreasing the differential pressure (DP). Moreover, the experiments using a test section simulating a reactor of the system had been conducted under the hydrogen condition simulating typical condition of a SA, by loading the granulated CuO with a diameter of 2mm onto the granulated MnO2 with a diameter of 1mm. As a result, the hydrogen treatment was markedly accelerated by supplying enough reaction heat from the granulated MnO2 to the granulated CuO.
Wave-shaped vanes are widely used in various power and energy systems for improved efficiency and prevention of droplet erosion. The vanes consist of wave-shaped parallel plates with pockets. As wet steam flows through the wave-shaped path, heavier droplets are thrown to the outside and captured in the pockets while frequently changing direction. However, microscale droplets are difficult to completely catch since they flow straight with the steam and are carried over through the wave-shaped vanes. Accordingly, we previously investigated installing a wire mesh at the inlet of the wave-shaped vanes to enhance the droplet capture efficiency by enlarging the microdroplets. In the present study, we examined the effect of the wire mesh configuration on enlarging the microdroplet size through air-water experiments. Droplet diameters were measured by a real-time image processing system consisting of a CCD camera and pulsed laser light source. The results showed that the droplet diameter distribution largely depended on the wire mesh configuration. We evaluated the mass flow ratio for droplets with a diameter smaller than the threshold diameter. The ratio was smallest in the case of the six-layer configuration of 0.65 mm diameter compared with two other cases, 0.19 and 0.80 mm, whereas the pressure loss was largest in the case of 0.19 mm. We conducted flow visualization at the outlet of the wire mesh using a high-speed camera. The visualization results showed that a liquid film had formed over the layered wire mesh and the surface wave of the liquid film on the last layer induced the detachment of enlarged droplets from the liquid film.
The mois 加 re separEtOr reheater ( MSR ) is a 飽cility which is used tO improve the thermal efficiency for the nude 肛 power plant. We have been developing the technique to improve moistUre sep 町 ad e 伍 ci 。ncy of MSR uSing wire − mesh combined with wave −shap θ d vanes . The o 切 eodve of this s加 dy is to clarify 止 e wirc −mesh eonfigurations which can minimize the exit mois 財 e by droplGt diameter measurement . We oon 丘rrned that dropl ¢ t diameters were increased and 止 e eXit moisture was reduced as the number of layer was incr ¢ ased . Withirt our ercperiment range , six layered鵬 mesh 覇 th O. 65 丗 aneter 町 血 imize止e moi 血 rc . 曲 ich is r瓠 uced m O. 45% 輌 thout wiremesh to O. 08% . κe γ Words : MVfre −mesh , Mo ' sture se ρaration, ルiicrodro ρ let , ルfS 尺
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