Steam turbine rotor, steam turbine using the rotor, and thermal power plant using same

Abstract

It is an objective of the invention to provide a steam turbine rotor of which a rotor shaft is made of a low-cost heat resistant ferritic steel and that can withstand high main steam temperatures of about 650 DEG C; a steam turbine using the rotor and a thermal power plant using same. There is provided a steam turbine rotor comprising: a rotor shaft made of a heat resistant ferritic steel such as a 12-Cr steel; and a rotor blade made of a Ti-Al alloy, wherein the Ti-Al alloy includes: from 38 to 45 atomic % of Al; from 0.5 to 2 atomic % of V; from 2 to 6 atomic % of Cr and / or Mo; and the balance being Ti and incidental impurities.

Description

technical field [0001] The present invention relates to the technology of steam turbine rotors, and in particular, to a steam turbine rotor using conventional ferritic heat-resistant steel as a rotor shaft and capable of coping with an increase in main steam temperature, a steam turbine using the steam turbine rotor, and its use The thermal power generation unit with the steam turbine. Background technique [0002] In recent years, from energy saving (for example, the conservation of fossil fuels) and global environmental protection (for example, CO 2 From the viewpoint of suppressing the amount of gas generated), it is desired to improve the efficiency of the thermal power generation unit (for example, to improve the efficiency of the steam turbine). As one of the effective means for improving the efficiency of the steam turbine, there is an increase in the temperature of the main steam. For example, in the current state-of-the-art ultra-supercritical pressure (USC) gener...

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Problems solved by technology

[0011] The main steam temperature of the 700°C class has been the long-term goal of steam turbines, so many researches and developments have been carried out for practical use. Unfortunately, the 700°C class A-USC steam turbines have not yet been put into practical use.

[0012] However, the material cost of nickel-based superalloys resistant to the main steam temperature of 700°C class is very high, so it may offset the economic advantages brought by the practical use of 650°C class generator sets

On the other hand, the durable temperature of the rotor shaft made of ferritic heat-resistant steel is usually 620°C as the limit when considering the centrifugal load stress applied to the rotor shaft. It is not easy to increase the durable temperature of the rotor shaft to 650°C

[0013] In addition, in general, ferritic heat-resistant steel has relatively low index density in matrix grains, so it has the advantages of less microstructural changes even under high-temperature and long-term environments and excellent long-term stability / reliability , but has the weakness of low mechanical strength at high temperature

Austenitic heat-resistant steel has the advantages of superior high-temperature strength and oxidation resistance, but has a weakness in thermal fatigue caused by temperature changes due to a relatively large thermal expansion coefficient (that is, a weakness in long-term stability / reliability )

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