Steam turbine, partition member, and method for operating steam turbine

A partition member for a steam turbine that partitions a high-pressure stage to which steam is supplied and a low-pressure stage to which the steam passed through the high-pressure stage is introduced, and is used in the steam turbine including a pressure regulation valve configured to regulate pressure of extraction steam or pressure of steam to be mixed, the partition member comprising:

• a bypass passage configured to make the high-pressure stage side and the low-pressure stage side communicate with each other without passing through the pressure regulation valve that is disposed in a region including outer peripheral side relative to the partition member;
• a high-pressure side partition part facing the high-pressure stage;
• and
• a low-pressure side partition part facing the low-pressure stage, wherein
• the partition member is an annular member provided separately from a cabin accommodating the high-pressure stage and the low-pressure stage, and
• the bypass passage includes:
• openings that make the high-pressure stage side relative to the high-pressure side partition part and a gap between the high-pressure side partition part and the low-pressure side partition part, communicate with each other;
• and
• a nozzle hole for the steam that leads from the gap to the low-pressure stage side.

A method for operating a steam turbine, the steam turbine including a partition section that partitions a high-pressure stage to which steam is supplied, and a low-pressure stage to which the steam passed through the high-pressure stage is introduced, and a pressure regulation valve configured to regulate pressure of a first steam or a second steam, the first steam being extraction steam that is a part of the steam passed through the high-pressure stage, the second steam being steam to be mixed flowing from outside into the steam passed through the high-pressure stage,

• the pressure regulation valve includes:
• a plurality of flow rate regulation valves that are located on outer peripheral side relative to the partition section and to which the first steam or the second steam is guided from the high-pressure stage side relative to the partition section;
• and
• a plurality of flow path compartments that:
• correspond to the respective flow rate regulation valves, and
• communicate with the low-pressure stage side relative to the partition section through respective nozzle holes, and
• guide the first steam or the second steam passed through the respective flow rate regulation valves to the low-pressure stage,
• the plurality of flow path compartments are arranged over the entire partition section in a circumferential direction in a region including the outer peripheral side relative to the partition section as a whole,
• the plurality of flow path compartments include:
• first parts that extend in parallel from the position of the flow rate regulation valves toward the partition section;
• second parts that are formed by dividing, in the circumferential direction, a space between a high-pressure side partition part of the partition section facing the high-pressure stage and a low-pressure side partition part of the partition section facing the low-pressure stage;
• and
• the nozzle holes for the first steam or the second steam that are prepared for the respective flow path compartments and lead from the respective second parts to the low-pressure stage side,
• the partition section is a partition member that is formed integrally with a cabin accommodating the high-pressure stage and the low-pressure stage, or a partition member provided separately from the cabin,
• the partition section includes the high-pressure side partition part facing the high-pressure stage and the low-pressure side partition part facing the low-pressure stage, and
• the partition section further includes:
• a bypass passage including:
• openings that make the high-pressure stage side relative to the high-pressure side partition part and the second parts located between the high-pressure side partition part and the low-pressure side partition part, communicate with each other;
• and
• the nozzle holes that lead from the respective second parts to the low-pressure stage side,
• the method comprising:
• controlling the pressure of the first steam or the second steam by regulating a flow rate of the steam to be introduced to the low-pressure stage through the pressure regulation valve that is disposed in a region including outer peripheral side relative to the partition section;
• and
• constantly introducing the steam from the high-pressure stage side to the low-pressure stage side through the bypass passage provided in the partition section without passing through the pressure regulation valve while the high-pressure stage and the low-pressure stage are rotated.