Two-Shaft Gas Turbine Exhaust Diffuser Design
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Solution Overview
Problem
Existing gas turbine plants face challenges in achieving high efficiency during updates due to output, spatial, and cost constraints, with existing methods often requiring new structures that increase costs and complexity, particularly in reducing losses at the exhaust diffuser and support members.
Innovation Solution
The modification of a one-shaft gas turbine to a two-shaft gas turbine configuration, where the high-pressure and low-pressure turbines share a common axis but operate at different rotational speeds, allowing for reduced axial length and increased efficiency without the need for additional components like decelerators, and the use of a specially designed exhaust diffuser with support members that suppress fluid flow interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a one-shaft gas turbine is updated to a two-shaft gas turbine configuration, then efficiency and power generation performance are improved, but device complexity increases
Solution Approach 1:
The single turbine shaft is segmented into two separate shafts: a high-pressure turbine shaft and a low-pressure turbine shaft. This segmentation allows each shaft to operate at its optimal rotational speed independently, improving overall power generation efficiency while maintaining manageable complexity through modular design
Solution Approach 2:
The system transitions from a static single-shaft configuration to a dynamic two-shaft configuration where each shaft can rotate at different speeds. This dynamic operation enables optimization of energy extraction at different stages, enhancing productivity without requiring complete redesign of the entire turbine system
2Length of moving object
If the axial length of the gas turbine is reduced to fit spatial constraints, then ease of installation is improved, but the ability to accommodate efficient turbine stages is worsened
Solution Approach 1:
The patent utilizes the radial dimension by positioning the high-pressure and low-pressure turbine stages in series along the radial direction rather than extending them axially. This dimensional rearrangement allows the turbine to achieve sufficient length for efficient stages while maintaining a compact axial footprint, solving the spatial constraint problem
3Loss of energy
If support members are added to the exhaust diffuser to reduce flow losses, then loss reduction is achieved, but device complexity and interference with fluid flow increase
Solution Approach 1:
Instead of adding multiple support members throughout the exhaust diffuser, the patent applies local quality by positioning support members strategically only at specific locations where flow separation occurs. This localized approach reduces flow losses effectively while minimizing overall structural complexity and interference with the fluid flow path
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
This approach enables a highly efficient gas turbine plant with reduced fuel consumption and CO2 emissions, while maintaining or reducing the axial length and eliminating the need for decelerators, thus overcoming spatial and cost limitations.
Implementation Method 1
a compressor for compressing air
Implementation Method 2
a combustor for generating a combustion gas from the air compressed by the compressor and a fuel
Implementation Method 3
a turbine driven by the combustion gas generated by the combustor
Data Source
AI summary
A method of modifying a gas turbine plant which is provided with a one-shaft gas turbine having a compressor for compressing air, a combustor for generating a combustion gas from the air compressed by the compressor and a fuel, and a one-shaft turbine driven by the combustion gas generated by the combustor and supported by a rotational axis common to the compressor, and an electric generator for generating electric power by driving force of the one-shaft turbine, wherein: the one-shaft turbine is replaced with a two-shaft gas turbine including a compressor for compressing air, a combustor for generating a combustion gas from the air compressed by the compressor and a fuel, and a high-pressure turbine driven by the combustion gas generated by the combustor and supported by a first rotational axis common to the compressor, and a low-pressure turbine driven by the combustion gas used to drive the high-pressure turbine and supported by a second rotational axis, which is different from the axis for the high-pressure turbine.