Effect of water level on performance of swirl-vane separator and steam dryer in PWR SG

Abstract

Swirl-vane separator and steam dryer work as primary and secondary separator in PWR SG to supply the dry-saturation steam for the turbines to generate electricity. In this paper, steam-water two-phase experiment is conducted to investigate the effect of water level on the separation efficiency, moisture carryover (MCO) and pressure drop of swirl-vane separator and steam dryer, respectively. The operation pressure is 6 MPa and the mass flowrate of steam and water are 3.81–11.73 kg/s and 7.62–70.40 kg/s, corresponding to 50–154% full power and 3–7 circulation ratio under prototypical conditions. For swirl-vane separator, the results indicate that the separation efficiency decreases (or MCO increases) with power load and circulation ratio at normal-water level, while it decreases more significantly with power load and the dependence on circulation ratio becomes complex at high-water level. The separator pressure drop increases with power load and circulation ratio increasing, but the influence of water level is minor. In terms of steam dryer, at both normal and high-water level, the separation efficiency and MCO exhibit minor change with power load and circulation ratio below the critical load (e.g. 120%–140%). Otherwise, MCO increases (or separation efficiency decreases) rapidly with power load and circulation ratio, and its value changes from 0.1% to 1.9% at normal-water level and from 1.0% to 22.4% at high-water level. The dryer pressure drop increases with power load while the influence of circulation ratio and water level is minor. Overall, the high-water level deteriorates the separation efficiency but has little influence on pressure drop of steam separator package in nuclear SG.