Compressor Casing Heat Exchanger for Gas Turbine Clearance Control
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Solution Overview
Problem
Gas turbine engines face challenges in maintaining optimal compressor blade clearances during low power demand and load transitions, leading to potential rotor blade damage from rubbing and reduced performance due to differing thermal expansion rates between the casing and rotor blades.
Innovation Solution
A compressor clearance control system that utilizes hot exhaust gases from the turbine to heat the compressor casing through a heat exchanger, controlling thermal contraction and expansion to maintain stable clearances, thereby preventing rubbing and optimizing power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If inlet guide vanes are closed to reduce airflow and power output, then fuel consumption is reduced, but compressor casing temperature drops causing rotor blade rubbing
Solution Approach 1:
The patent converts the harmful cold exhaust gases into a beneficial heating medium by routing them through a heat exchanger to warm the compressor casing. This transforms the waste cold flow into a useful thermal resource that prevents rotor blade rubbing while maintaining low power output conditions, effectively solving the clearance stability problem without sacrificing fuel efficiency.
Solution Approach 2:
The patent introduces a heat exchanger as an intermediary component between the exhaust gas system and the compressor casing. This mediator transfers thermal energy from the cold exhaust gases to the compressor casing without direct mixing of the flows, enabling temperature control of the casing to maintain proper rotor blade clearances during low power operation.
2Reliability
If steady state clearances are increased to prevent rotor blade rubbing, then reliability is improved, but core flow capacity is reduced
Solution Approach 1:
The patent implements dynamic clearance control by actively managing the thermal state of the compressor casing through the heat exchanger system. Rather than using fixed steady-state clearances, the system dynamically adjusts casing temperature to maintain optimal clearances across varying operating conditions, thereby preserving core flow capacity while preventing rotor blade rubbing during transitions.
3Reliability
If compressor extraction air is used for active clearance control, then rotor blade clearance is controlled, but system complexity increases
Solution Approach 1:
The patent makes the exhaust gas heat exchanger system multi-functional by using it for both waste heat recovery and compressor casing temperature control. The same infrastructure that handles exhaust gas management also serves the clearance control function, eliminating the need for separate extraction air systems and reducing overall system complexity while maintaining effective rotor blade clearance control.
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 system allows for lower turndown without risking rotor blade damage, promotes higher power output, and reduces efficiency penalties associated with existing heat management techniques by using waste heat to control casing temperature.
Implementation Method 1
A compressor clearance control system that utilizes hot exhaust gases from the turbine to heat the compressor casing through a heat exchanger
Implementation Method 2
controlling thermal contraction and expansion to maintain stable clearances
Data Source
Figure 1~2
Figure 3~4
AI summary
The present application provides a compressor clearance control system (100) for a gas turbine engine (10). The gas turbine engine (10) includes a turbine (40) producing exhaust gases and a compressor (20) with a casing (24) and a number of rotor blades (26). The compressor clearance control system (100) may include an casing heat exchanger (110) positioned about the casing (24) of the compressor (20) and an extraction (120) of exhaust gases from the turbine (40). The extraction (120) is in communication with the casing heat exchanger (110) so as to heat the casing (24) of the compressor (20) with the exhaust gases from the turbine (24).