Extra-High-Pressure Turbine Casing Cooling and Material Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional steam turbine power generation systems face challenges in achieving high efficiency and economical productivity when operating with high-temperature steam due to the limitations of ferrite-based materials, particularly in maintaining mechanical characteristics and environmental resistance at temperatures above 600°C, and the poor workability and productivity of Ni base alloys and austenite-based materials.
Innovation Solution
A steam turbine power plant design incorporating a double-structured casing with an outer and inner casing, utilizing heat-resisting alloys and cast steel with specific chemical compositions for the turbine rotor, inner casing, and nozzle box, along with cooling units to manage high-temperature steam of 650°C or more, ensuring thermal efficiency, reliability, and economical efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ferrite-based heat-resisting steel is used for steam turbine main members, then workability and productivity are improved, but mechanical characteristics and environment resistance deteriorate at temperatures above 600°C
Solution Approach 1:
The steam turbine is divided into high-temperature portions (nozzle, rotor, inner casing) and low-temperature portions (outer casing, other components). The high-temperature portions use Ni base alloy or austenite-based material to withstand 650°C steam, while other portions use conventional ferrite-based material, combining the advantages of both material types.
Solution Approach 2:
Different materials are applied to different parts of the steam turbine based on local temperature requirements. Ni base alloy and austenite-based material are used specifically in high-temperature zones where mechanical characteristics are critical, while ferrite-based material is used in lower-temperature zones where workability is more important.
2Reliability
If Ni base alloy or austenite-based material is used for high-temperature turbine portions, then mechanical characteristics and environment resistance are improved, but workability, productivity and economical efficiency deteriorate
Solution Approach 1:
The steam turbine is divided into high-temperature portions (nozzle, rotor, inner casing) and low-temperature portions (outer casing, other components). The high-temperature portions use Ni base alloy or austenite-based material to withstand 650°C steam, while other portions use conventional ferrite-based material, combining the advantages of both material types.
Solution Approach 2:
Different materials are applied to different parts of the steam turbine based on local temperature requirements. Ni base alloy and austenite-based material are used specifically in high-temperature zones where mechanical characteristics are critical, while ferrite-based material is used in lower-temperature zones where workability is more important.
3Use of energy by moving object
If steam temperature is raised to 650°C or more to improve power generation efficiency, then energy saving and high efficiency are achieved, but applicability of conventional steam turbine structure deteriorates
Solution Approach 1:
The steam turbine is divided into high-temperature portions (nozzle, rotor, inner casing) and low-temperature portions (outer casing, other components). The high-temperature portions use Ni base alloy or austenite-based material to withstand 650°C steam, while other portions use conventional ferrite-based material, combining the advantages of both material types.
Solution Approach 2:
The material parameters (composition, microstructure) are changed for specific components to enable them to withstand the elevated steam temperature of 650°C or more, while maintaining the overall conventional steam turbine structure for components that do not require such high temperature resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design allows for the effective introduction of high-temperature steam into the steam turbine, improving thermal efficiency while ensuring reliability, operability, and economical efficiency by using ferrite-based alloy steels for critical components and cooling units to manage thermal stress.
Implementation Method 1
an outer casing cooling unit which cools the outer casing by introducing cooling steam between the outer casing and the inner casing
Implementation Method 2
a turbine rotor of the extra-high-pressure turbine is formed of a heat-resisting alloy which contains in percent by weight C: 0.10-0.20, Si: 0.01-0.5, Mn: 0.01-0.5, Cr: 20-23, Co: 10-15, Mo: 8-10, Al: 0.01-1.5, Ti: 0.01-0.6, B: 0.001-0.006 and the balance of Ni and unavoidable impurities
Data Source
AI summary
A steam turbine power plant which is provided with an extra-high-pressure turbine 100, a high-pressure turbine 200, an intermediate-pressure turbine 300 and a low-pressure turbine 400, and has high-temperature steam of 650° C. or more introduced into the extra-high-pressure turbine 100, wherein the extra-high-pressure turbine 100 has an outer casing cooling unit which cools an outer casing 111, and a turbine rotor 112, an inner casing 110 and a nozzle box 115 of the extra-high-pressure turbine 100 are formed of an Ni base heat-resisting alloy, and the outer casing 111 is formed of a ferrite-based alloy.