Full-scale numerical study on the thermal-hydraulic characteristics of steam-water separation system in an advanced PWR UTSG. Part two: Droplets separation process

Performance of the separation system in the UTSG determines the quality of supplied steam in a nuclear power plant. In the present study, the Eulerian-Lagrangian methodology is applied in a full-scale UTSG separation system of GEN-III China advanced PWR. Detailed flow characteristics and separation performance of the whole system are investigated. Effects of the steam velocity and droplets sizes on the separation process are also discussed. Last but not least, the mal-distribution phenomena in dryers are analyzed. Results illustrate that the separators at the hot side have a better performance than the ones at the cold side, and the separation efficiency falls within the range from 98.16% to 99.39% in the current system. What's more, both the steam velocity and the droplets radii have obvious effects on the separation performance. For dryers, obvious mal-distribution phenomena are estimated. As a result of the lower efficiency of separators at cold side, the #7 dryer suffers the maximum loading of entrained water on unit-area (1.24kg/(m2·s)), and the greatest humidity at entrances of dryers is observed to be 4.90% accordingly. In general, the present work could be expected to be the assessment and basis of UTSG separation system optimization for China advanced PWR.