Seal Structure and Control Method Therefor

Abstract

Provided are a seal structure and a control method therefor that can improve sealing performance between a rotating portion and a fixed portion, smoothly start up a steam turbine, and suppress the temperature rise of the rotating portion even if the rotating portion is continuously rotated for a long period of time.A seal structure is configured such that seal fins 62 on a seal base-plate 61 side and corresponding breathable spacers 4b on a rotor 2a side are opposed to each other and breathable spacers 4a on the seal base-plate 61 side and corresponding seal fins 2a1 on the rotor 2a side are opposed to each other. The seal base-plate 61 is installed shiftably in a direction coming close to or moving away from the rotor 2a. If steam St has low pressure, the seal fins 62 and the corresponding breathable spacers 4b are not in contact with each other and the seal fins 2a1 and the corresponding breathable spacers 4a are not in contact with each other. If the steam St has high pressure, the seal fins 62 and the corresponding breathable spacers 4b are in contact with each other and the seal fins 2a1 and the corresponding breathable spacers 4a are in contact with each other.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a seal structure provided for a steam turbine and a control method therefor.[0003]2. Description of the Related Art[0004]For power-generating plants in which a turbine (steam turbine) is rotated for electric generation by steam generated by a steam generator such as a boiler or the like, the steam turbine includes a high-pressure turbine, a medium-pressure turbine and a low-pressure turbine installed in that order from the upstream side of steam flow. The steam having rotated the low-pressure turbine is introduced via an exhaust hood into a condenser, in which the steam is condensed as feed-water, which is returned to the steam generator.[0005]In the steam turbine constituting part of the power-generating plant as described above, a stator blade secured to the inside of a casing is disposed between rotor blades rotated integrally with a rotor. In this way, the stator blade and the rotor ...

AI Technical Summary

Benefits of technology

[0015]If the clearance between the fins and the abradable metal is increased in order to prevent the contact between the fins and the abradable metal, the clearance between the rotating portion and the fixed portion is increased to increase the leakage of steam. Thus, it is not probable that the turbine efficiency of the steam turbine can be improved.

[0016]Accordingly, it is an object of the present invention to provide a seal structure and a control method therefor that can improve sealing performance between a rotating portion and a fixed portion, smoothly start up a steam turbine, and suppress the temperature rise of the rotating portion even if the rotating portion is continuously rotated for a long period of time.

[0018]The aspect of the present invention can provide the seal structure and the control method therefor that can improve sealing performance between the rotating portion and the fixed portion, smoothly start up a steam turbine, and suppress the temperature rise of the rotating portion even if the rotating portion is continuously rotated for a long period of time.

Problems solved by technology

In the technology disclosed in JP-2007-16704-A, however, if the rotating portion is continuously rotated for a long period of time so that the fins and the abradable metal are in contact with each other for a long period of time, the frictional heat thus generated is accumulated in the thermal insulation layer.

This poses a problem in that the heat accumulated in the thermal insulation layer is transmitted to the rotating portion, which has high-temperature.

When the contact between the fins and the abradable metal increases rotational resistance and steam pressure is low, the rotor does not rotate smoothly so that the smooth start-up of the steam turbine cannot be achieved.

Thus, it is not probable that the turbine efficiency of the steam turbine can be improved.

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