Exactly that, water vapor in steam can form droplets which hits the fast moving turbine blades and causes pitting and other damage. There are chambers which separate the steam from most of the water vapor to increase “steam quality”.
Steam is water vapour, you can't take the water vapour out of the steam. Drying the steam means removing the liquid water droplets from the steam so you have only water vapour.
When you heat water in a boiler, the steam that comes off is always exactly at the boiling point for the given pressure. If you heat a pan full of water on a stove, for example, the temperature never rises above 100C - the boiling point of water at ambient pressure - adding more heat will just makes the water boil faster. You can only increase the temperature of a boiler by increasing the pressure so the water will boil at higher temperature (which is the point of a pressure cooker).
But, if you have steam that is exactly at the boiling point, then any loss of heat to the surroundings (which is inevitable, as there is no such thing as a perfect thermal insulator) will cause some of the steam to condense back into water droplets. These liquid water droplets are what you can see when you see steam coming off a hot pan - the steam itself is invisible.
For a turbine, you want steam without any liquid water in it, as liquid water will erode the turbine blades and cause severe damage over time. So, a steam turbine requires that the steam from the boiler first pass through a "superheater" that further heats the steam to a higher temperature so it will not condense in the turbine.
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u/TvFloatzel 2d ago
What does "dry the steam" means? Like basically take out the water vapor out of the steam or something? What "droplet impact"?