Turbine Gland Spill Over Steam

Gland steam is used on condensing turbines in order to prevent the ingress of air at the exhaust side shaft extension.

Gland steam, usually low pressure steam, is injected into the labyrinth, most is "sucked" into the turbine exhaust, some is then vented to atmosphere via a small pipe to a few meters above the turbine shaft where a small wisp of steam should always be visible. If you push too much steam to the gland then it will also come out of the turbine along the shaft - I guess you could call this "gland spill over steam"