Gas Turbine Load Coupling Cooling via Forced Air Convection
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Solution Overview
Problem
Existing load-coupling cooling systems in gas turbines suffer from thermal deformation issues due to high temperatures, leading to axial forces on bearings and potential dynamic stresses and vibration, with prior solutions like fan blades causing rotodynamic behavior modifications and potential failure.
Innovation Solution
A forced air convection system is implemented to actively remove heat from the load coupling, using a cooling air circulation system that channels air from the turbomachinery compartment to surround the load coupling, reducing thermal deformation and mechanical stress without the need for fan blades or separate cooling devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fan blades are mounted on the load coupling to generate cooling air stream, then cooling effect is improved, but rotodynamic behavior is modified causing dynamic stresses and vibration
Solution Approach 1:
The cooling function is extracted from the load coupling itself by removing the fan blades mounted on the load coupling shaft. Instead, a separate cooling system with its own air source and circulation path is provided, allowing the load coupling to operate without the harmful rotodynamic modifications while still achieving effective cooling through dedicated cooling air streams.
Solution Approach 2:
A separate cooling air circulation system acts as an intermediary between the cooling requirement and the load coupling. This intermediate system provides cooling air through dedicated passages and channels, preventing the direct coupling of fan blades to the load coupling shaft, thereby eliminating the transmission of harmful dynamic stresses and vibration to the rotodynamic components.
2Shape
If thermal expansion of the shaft is compensated by arranging a joint, then thermal deformation is reduced, but axial forces are generated on the bearings
Solution Approach 1:
The mechanical joint system that compensates for thermal expansion is replaced with a thermal management system. By actively controlling the temperature of the load coupling and shaft through forced air convection, the thermal expansion is minimized at the source, eliminating the need for mechanical compensation joints and the associated axial forces on bearings.
3Temperature
If separate cooling devices or fan blades are added to cool the load coupling, then cooling effectiveness is improved, but device complexity increases
Solution Approach 1:
The cooling system is merged with the existing gas turbine infrastructure by utilizing the gas turbine's own air intake and exhaust systems as part of the cooling circuit. The cooling air passages are integrated into the load coupling structure itself, and the system is controlled through the existing gas turbine control mechanisms, thereby achieving effective cooling without adding separate standalone cooling devices or fan blades.
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 effectively reduces thermal and mechanical stresses on the load coupling, minimizing axial loads on turbine and load bearings, enhancing system reliability and efficiency while maintaining a compact design.
Implementation Method 1
heat is actively removed by forced air convection from the load coupling
Implementation Method 2
a stream of cooling air from the environment through a guard surrounding the load coupling
Implementation Method 3
Thermal deformation of the shaft 7 must be sagged, i.e. measures must be adopted to prevent the thermal expansion of the shaft 7
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A gas turbine (33) is described, comprising at least a compressor (43), a power turbine (47), a load coupling (35) connecting said gas turbine (33) to a load (37), a load-coupling guard (65) at least partly surrounding the load coupling (35), a cooling air channeling (51, 61, 63) designed and arranged to circulate a cooling air flow in the load-coupling guard sufficient to remove heat from the load coupling (35).