Evaluation of a Steam Dryer used in Steam Generators

Abstract

The hooked-vane-type dryer is used in vertical, natural circulation steam generators used in PWR-type nuclear power stations. It separates the fine droplets of water carried by steam so that the steam generator outlet steam moisture is below 0.25%. Such low moisture is demanded to ensure a safe and economic operation of the unit. The dryer is composed of hooked vanes and a draining structure. A series of tests to screen different designs were performed using air-water mixture. The paper presents the results of the investigation of the effect of the number of drainage hooks, the bending angle, distance between two adjacent vanes, and other geometrical parameters on the performance of a hooked-vane-type steam dryer. It indicates that the dryer still works effectively when the moisture of the steam at the dryer inlet changes in a wide range. and that the performance of the dryer is closely related to the geometry of the draining structure. On the basis of the results of this program, a draining structure with an original design was selected and it is presented in the paper. The performance of the selected draining structure is better than that of similar structures in China and abroad.