Method and apparatus for controlling the operation of a steam turbine

A diaphragm assembly for a steam turbine, the steam turbine including a rotor and a plurality of bucket stages coupled to the rotor, said diaphragm assembly comprising:

• a plurality of nozzle stages configured to be positioned between the bucket stages;
• a circumferentially extending groove, said groove located upstream from one bucket stage and between the one bucket stage and a nozzle stage that is positioned upstream from the bucket stage and adjacent to the one bucket stage;
• a circumferentially extending extraction chamber;
• at least one first bore extending from said groove to said extraction chamber, said at least one first bore providing bi-directional fluid communication between said groove and said extraction chamber;
• and
• at least one second bore extending from said extraction chamber through an outer surface of said diaphragm assembly;
• said at least one second bore providing bi-directional fluid communication between said extraction chamber and an area outside of said diaphragm assembly.

A method of controlling the operation of a steam turbine, the steam turbine comprising a rotor, a plurality of bucket stages coupled to the rotor, and an outer casing disposed about the rotor, each bucket stage comprising a plurality of circumferentially spaced buckets coupled to the rotor, each bucket comprising a base portion and a tip portion;

• said method comprising:
• providing a diaphragm assembly to surround the rotor and bucket stages, the diaphragm assembly comprising:
• a plurality of nozzle stages located between the bucket stages;
• a circumferentially extending groove, the groove located upstream from one of the bucket stages and between that bucket stage and an adjacent nozzle stage positioned upstream from the bucket stage;
• a circumferentially extending extraction chamber;
• at least one first bore extending from the groove to the extraction chamber, the at least one first bore providing bi-directional fluid communication between the groove and the extraction chamber;
• and
• at least one second bore extending from the extraction chamber through an outer surface of the diaphragm assembly;
• the at least one second bore providing bi-directional fluid communication between the extraction chamber and an area between the outer surface of the diaphragm assembly and the outer casing.