Two-Shaft Gas Turbine Load Balancing Without Variable Vanes
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Solution Overview
Problem
Two-shaft gas turbines face performance issues when atmospheric temperatures differ from design temperatures, as the inlet temperature of the high-pressure turbine and air quantity of the compressor do not simultaneously reach rated values, leading to suboptimal operation without the use of variable stator vanes in the low-pressure turbine.
Innovation Solution
A two-shaft gas turbine configuration that includes a gas generator, a high-pressure turbine, a fixed-vane low-pressure turbine, and a control unit that adjusts the load using a generator motor or other load adjustors to balance the rotor vane balance between the high-pressure and low-pressure turbines, ensuring both the inlet temperature and air quantity reach rated values regardless of atmospheric temperature without relying on variable stator vanes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a variable stator vane is used in the initial stage of the low-pressure turbine to adjust the rotor vane balance, then both the inlet temperature of the high-pressure turbine and air quantity of the compressor can reach rated values, but the device complexity increases and the vane requires cooling configuration
Solution Approach 1:
The patent removes the variable stator vane from the initial stage of the low-pressure turbine and instead places a variable vane at the inlet of the compressor. This extraction eliminates the need for complex cooling configurations in the turbine vane while achieving the same performance benefit of balancing the rotor vane relationship between high-pressure and low-pressure turbines.
Solution Approach 2:
The patent introduces a variable vane at the compressor inlet as an intermediary device to control the air quantity entering the system. This mediator allows indirect adjustment of the rotor vane balance by controlling the mass flow at the source, avoiding the need for direct intervention in the turbine section.
2Temperature
If the inlet temperature of the high-pressure turbine is raised to compensate for higher atmospheric temperature, then the air quantity of the compressor can reach rated value, but the initial-stage stator vane of the low-pressure turbine requires cooling configuration
Solution Approach 1:
The patent extracts the temperature control function from the low-pressure turbine stator vane section and relocates it to the compressor inlet variable vane. By controlling the air quantity at the compressor inlet, the system can adjust the inlet temperature to the high-pressure turbine without requiring cooling configurations in the turbine section.
3Temperature
If a cooled vane configuration is used in the initial stage of the low-pressure turbine, then the vane can withstand higher inlet temperatures, but the ease of manufacture decreases and operational flexibility is reduced
Solution Approach 1:
The patent removes the cooled vane configuration requirement from the low-pressure turbine by relocating the temperature and flow control function to the compressor inlet variable vane. This extraction simplifies the turbine vane design to a fixed, non-cooled configuration that is easier to manufacture while maintaining the ability to control operating conditions.
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 configuration allows the two-shaft gas turbine to maintain optimal performance by adjusting the load to ensure the inlet temperature and air quantity of the compressor reach rated values at any atmospheric temperature, enhancing operational efficiency without the need for variable stator vanes in the low-pressure turbine.
Implementation Method 1
a small motor/generator was added to the gas generator spool of the gas turbine engine in order to adjust the compressor speed and airflow
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A two-shaft gas turbine is provided that can raise an inlet temperature of a high-pressure turbine and the air quantity of a compressor to respective rated values at any atmospheric temperature without using a variable stator vane in the initial stage of a low-pressure turbine. The two-shaft gas turbine includes a power generator 21 having a compressor 11, a combustor 12 and a high-pressure turbine 13; a low-pressure turbine 14 driven by exhaust gas from the high-pressure turbine 13; a generator motor 23 connected to the gas generator 21; and a control unit 24. When either one of a value of the inlet temperature of the high-pressure turbine 13 and a value of the air quantity of the compressor 11 reaches a rated value before the other value reaches a rated value, the control unit 24 drives the generator motor 23 to bring the other value close to the rated value.