Visualized measurement of extremely high-speed droplets in Venturi scrubber

Horiguchi, Naoki   ; Yoshida, Hiroyuki  ; Abe, Yutaka*

Venturi scrubber (VS) has been installed in NPPs as one of the components of filtered venting systems. It can eliminate fine aerosol particles including fission products from polluted gas. Under extremely high-velocity conditions during severe accident, the data related to the droplet in the VS, which affects decontamination performance, is insufficient. This objective is to obtain the diameter of the extremely high-speed droplets and clarify an applicability of the existing correlations for the diameter. To visualize the extremely high-velocity droplet, an optical system with high frame rate and high resolution was developed. Visualization experiment using the VS under air-water condition was conducted, and droplet diameter distributions and Sauter mean diameter (SMD) were obtained. By comparing experimental data with values evaluated by existing correlations, it was clarified that the Nukiyama-Tanasawa equation can evaluate the SMD with good accuracy in the gas velocity range 82-250 m/s.