SOFC Air Supply Stabilization via Booster and Control Valves
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Solution Overview
Problem
Conventional power generation systems face instability during fuel cell starting due to rapid pressure and flow rate fluctuations in compressed air, leading to air shortages and inefficient combustion and cooling in gas turbines, and pressure instability affects the operating state of solid oxide fuel cells (SOFCs), impairing power generation efficiency.
Innovation Solution
A power generation system with a booster and control valves in the compressed air supply lines to stabilize air pressure and flow rate, ensuring constant air supply to the SOFC and preventing air shortages, using a booster circulation line and pressure control valves to maintain stable compressed air pressure during SOFC operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the flow rate of compressed air is rapidly increased to supply the SOFC during starting, then the SOFC can be pressurized and started, but the compressed air for the combustor becomes insufficient causing air shortage
Solution Approach 1:
The compressed air supply is divided into two separate controllable paths: one path supplies the combustor with sufficient air for combustion and cooling, while the other path supplies the SOFC with pressurized air through the blower. This segmentation allows independent control of air distribution to resolve the conflict between rapid SOFC pressurization and maintaining adequate combustor air supply.
Solution Approach 2:
The blower is introduced as an intermediary device specifically for the SOFC air supply line, while the combustor receives air directly from the compressor through a separate path. This intermediary allows the SOFC to receive pressurized air without compromising the combustor's air supply, as the blower handles the pressure boosting function for SOFC exclusively.
2Stress or pressure
If the blower is activated to provide pressure for SOFC starting, then the SOFC can operate, but rapid fluctuations in pressure and flow rate cause unstable operation
Solution Approach 1:
The gas turbine and compressor are started and stabilized before activating the blower for SOFC pressurization. This preliminary action ensures that the base compressed air supply is stable before introducing the blower, reducing the impact of blower-induced fluctuations on overall system stability.
Solution Approach 2:
Control mechanisms monitor pressure and flow rate parameters in the compressed air supply lines, providing feedback to adjust blower operation and control valve positions. This feedback control stabilizes the pressure and flow rate fluctuations caused by blower activation, maintaining stable SOFC operation.
3Adaptability or versatility
If the outlet pressure of the compressor fluctuates during gas turbine operation changes, then the gas turbine responds to power generation conditions, but the pressure of compressed air supplied to the SOFC becomes unstable
Solution Approach 1:
The blower serves as an intermediary pressure-stabilizing device in the SOFC air supply line. It compensates for pressure fluctuations from the compressor by maintaining consistent pressure delivery to the SOFC, allowing the gas turbine to respond to load changes without transmitting pressure instability to the SOFC.
Solution Approach 2:
Pressure control valves and control systems monitor the compressed air pressure before and after the blower, providing feedback to adjust valve positions and blower operation. This feedback mechanism decouples the SOFC pressure supply from compressor pressure fluctuations, maintaining stable SOFC operation during gas turbine load changes.
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 achieves stable starting and operation of the fuel cell by suppressing air shortages and maintaining constant air pressure, thereby ensuring efficient combustion, cooling, and stable power generation.
Implementation Method 1
a booster provided in the second compressed air supply line, boosting pressure of the compressed air
Implementation Method 2
controlling the flow rate of the compressed air, as necessary, such that the pressure of the compressed air is constant
Data Source
AI summary
The present invention enables a fuel cell to be stably started by minimizing a lack of air in a gas turbine when starting the fuel cell. This fuel cell system comprises: a gas turbine (11) having a compressor (21) and a combustor (22); a first compressed air supply line (26) that supplies compressed air (A1), which has been compressed by the compressor, to the combustor; a solid oxide fuel cell (SOFC) (13) having an air electrode and a fuel electrode; a second compressed air supply line (31) that supplies partially compressed air (A2), which has been compressed by the compressor, to the air electrode; a blower (33) that is disposed on the second compressed air supply line, and raises the pressure of the compressed air (A2); a circulation booster line (60) connecting the upstream side and downstream side of the blower in the second compressed air supply line; a control valve (61) disposed on the circulation booster line; a control valve (63) disposed between the circulation booster line in the second compressed air supply line and the SOFC; and a control device (62) that closes the control valves and opens the control valves to start the blower when starting the SOFC.