7.3 Gland steam condenser
The function of the gland steam condenser is to maintain a sub-atmospheric pressure at the outermost leak-off belt of the glands and thereby prevent the leakage of steam from the glands into the turbine hall, where it would condense on the walls and plant.
The condenser is vented to the atmosphere via a blower. The small vacuum created by the blower is sufficient to draw air into the glands where it mixes with steam leaking from the cylinder; the air is separated in the gland condenser and passed back to the atmosphere via the vent fans. The steam is condensed and the condensate passes to the main condenser. A typical gland steam condenser is shown in Fig 2.74.
The condenser typically consists of a steel shell closed by a dished-end waterbox cover incorporating a tubeplate into which are expanded U-tubes. Cooling water, provided by local river water or seawater, is circulated through the U-tubes to condense the steam. When the gland steam condenser is out of service, steam is prevented from escaping into the turbine hall by operating the vent fans.