Slugging (Steam Turbine)

A steam turbine is designed to operate on a superheated steam supply of high quality, at or very close to 1. (A steam quality of 0 indicates the stream is 100% water, whereas a steam quality of 1 indicates the stream is 100% steam.) Steam boilers are normally designed to provide high-quality steam. However, during startups and upset conditions, free water or condensate can collect and travel to steam turbines in the form of water slugs. This event, which is called water slugging, can cause failure of the thrust bearing, blading, shroud bands, and even lead to a shaft bow. Regular carryover events of free water will invariably lead to erosion on the blades, diaphragms, and rotors.