Method of and system for controlling stress produced in steam turbine rotor
AssigneeHitachi, Ltd.
InventorsKatsukuni Hisano, Hitoshi Isa, Hazime Sibaoka
Life of this patent
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Abstract
A stress controlling system for a rotor of a steam turbine determines thermal and rotational conditions of the rotor. Thermal and centrifugal stresses produced in the rotor during operation of the steam turbine are calculated from the thermal and rotational conditions, respectively, of the rotor. Also, brittle fracture toughness of the material of the rotor under the thermal condition determined is calculated. Operation of the steam turbine is controlled to prevent the calculated brittle fracture toughness from being exceeded by the combined stress of thermal and centrifugal stresses during operation of the steam turbine.
Claims11
In a method of controlling stress produced in a rotor of a steam turbine during operation of said turbine, said method comprising the steps of:
- determining thermal and rotational conditions of said rotor;
- calculating thermal and centrifugal stresses produced in said rotor from said thermal and rotational conditions, respectively;
- calculating brittle fracture toughness under said thermal condition of the material of said rotor, and
- controlling the operation of said turbine to prevent the combined stress of said thermal and centrifugal stresses from exceeding said brittle fracture toughness.
A method of controlling stress produced in a rotor of a steam turbine comprising the steps of:
- calculating the temperature of said rotor from the temperature detected at a predetermined portion of said steam turbine,
- calculating thermal and centrifugal stresses produced in said rotor from the temperature variation and rotation, respectively, of said rotor,
- calculating brittle fracture toughness at said calculated temperature of the material of said rotor, and
- controlling the operation of said turbine to prevent the combined stress of said thermal and centrifugal stresses from exceeding said brittle fracture toughness.
A system for controlling stress produced in a rotor of a steam turbine during operation of said turbine, comprising:
- first calculator means for calculating temperature of said rotor from thermal condition of said turbine;
- second calculator means for calculating thermal stress produced in said rotor from the temperature variations of said rotor;
- third calculator means for calculating centrifugal stress produced in said rotor from rotational condition of said rotor;
- fourth calculator means for calculating brittle fracture toughness at said temperature of the material of said rotor;
- comparator means for comparing the calculated brittle fracture toughness of said rotor with the combined stress of said thermal and centrifugal stresses;
- and
- means for controlling the operation of said steam turbine in response to an output signal of said comparator means.
Dependencies are inferred from the claim text.