Integrated Turbine Sealing Air and Active Clearance Control
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Solution Overview
Problem
Existing gas turbine designs face challenges in maintaining optimal blade tip clearances across varying load and temperature conditions, leading to inefficiencies and increased auxiliary power consumption due to complex and costly clearance control systems.
Innovation Solution
An active blade tip clearance control system that utilizes compressor bleed air to circulate through the inner turbine shell and compressor discharge casing, integrated with the gas turbine's cooling and sealing air system, to actively control blade tip clearances, eliminating the need for a complex skid and reducing auxiliary power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex clearance control system with separate skid and additional components is used, then blade tip clearance control capability is improved, but device complexity and auxiliary power consumption increase
Solution Approach 1:
The patent merges the clearance control function with the existing cooling air system by integrating the thermal circuit into the inner shell structure. The cooling air path serves dual purposes: cooling the turbine components and controlling blade tip clearances through thermal expansion/contraction of the inner shell, thereby eliminating the need for a separate clearance control skid and reducing system complexity
Solution Approach 2:
The cooling air system is designed to perform multiple functions simultaneously: it cools the turbine components, seals the gaps between rotating and stationary parts, and controls blade tip clearances through thermal effects on the inner shell. This multi-functionality eliminates the need for dedicated separate systems for each function, reducing overall device complexity
2Reliability
If a complex clearance control system with separate skid and additional components is used, then blade tip clearance control capability is improved, but auxiliary power consumption increases
Solution Approach 1:
The patent combines the clearance control function with the existing cooling air system, eliminating the need for a separate powered clearance control skid. The thermal circuit uses the same cooling air that is already being compressed and circulated for cooling purposes, thereby avoiding additional auxiliary power consumption while maintaining effective blade tip clearance control
3Productivity
If tight blade tip clearances are maintained through active control, then gas turbine efficiency is improved, but device complexity increases
Solution Approach 1:
The system uses the natural thermal expansion and contraction of the inner shell in response to cooling air temperature changes to automatically control blade tip clearances. This self-regulating mechanism eliminates the need for complex active control hardware such as motors, actuators, and control systems, while still achieving tight and stable blade tip clearances for optimized turbine efficiency
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 solution enhances gas turbine efficiency and reliability by maintaining tight blade tip clearances, reducing auxiliary power consumption, and simplifying the hardware components, thereby improving overall performance and reducing operational costs.
Implementation Method 1
by flowing a thermal medium in the described thermal circuit, the inner shell may contract and expand in a radial direction in response to flow of the thermal medium. Consequently, by controlling the thermal expansion or contraction in a radial direction of the inner shell relative to the tips of the buckets of the first and second stages, tip clearance control is afforded
Implementation Method 2
a flow path for directing a stream of compressor bleed air to circulate through a passage defined in at least one of (1) an inner turbine shell and (2) a compressor discharge casing to actively control the blade tip clearances therein
Data Source
AI summary
An active clearance control system is provided that uses compressor extraction air to manipulate blade tip clearance in an industrial gas turbine and compressor. A stream of air is taken from a cooling and sealing air circuit and redirected to be used for active clearance control. The spent clearance control air is re-introduced into the hot gas path of the gas turbine for cooling and sealing purposes.