Fuel Cell Air Feed Control for CO Emission Reduction
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Solution Overview
Problem
Fuel cell systems face issues with carbon monoxide emissions during start-up, leading to inefficient combustion and potential health hazards due to insufficient oxygen supply, which contaminates the catalyst and affects power generation performance.
Innovation Solution
Increasing the air feed rate to the combustor after switching the fuel gas destination to the combustor, ensuring sufficient oxygen for complete combustion of natural gas and reducing carbon monoxide emissions by using a bypass passage to fill the fuel cell with raw material gas before switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the air feed rate to the combustor is increased after switching fuel gas destination, then carbon monoxide emissions are reduced through complete combustion, but the system complexity increases due to dynamic air feed rate control requirements
Solution Approach 1:
The air feed rate control system dynamically adjusts the air feed rate based on operational state. During start-up or switching operations, the controller increases the air feed rate to ensure complete combustion and prevent carbon monoxide emissions. During normal operation, the air feed rate is maintained at optimal levels for efficiency.
Solution Approach 2:
The system employs a controller that monitors operational parameters and adjusts the air feed rate accordingly. The controller receives feedback from sensors detecting fuel gas flow, combustor temperature, and emission levels, then modulates the air feed rate to maintain complete combustion and minimize carbon monoxide emissions.
2Reliability
If the fuel cell is filled with raw material gas before switching, then catalyst contamination is prevented, but the response time for power generation starts is delayed
Solution Approach 1:
The system performs preliminary filling of the fuel cell with raw material gas (natural gas) before switching from hydrogen-containing fuel gas. This preliminary action ensures that the catalyst is not exposed to hydrogen during the transition period, preventing contamination and maintaining catalyst integrity for long-term reliable operation.
Solution Approach 2:
The fuel gas switching operation is performed in controlled periodic stages: first stopping hydrogen supply, then filling the fuel cell with natural gas over a predetermined period, and finally establishing normal natural gas operation. This staged periodic approach balances catalyst protection with acceptable start-up time.
3Object-affected harmful factors
If inert gas is fed to force out dwelling fuel gas during stop period, then rapid oxidation of hydrogen is prevented, but the system size and initial cost increase due to additional inert gas feeding means
Solution Approach 1:
The system uses the combustion burner, which is already an integral component of the reformer, to perform the function of forcing out dwelling fuel gas. By utilizing the existing combustion burner and its associated air supply system, the invention eliminates the need for separate inert gas feeding means, reducing system size and cost while still preventing rapid oxidation damage during stop periods.
Solution Approach 2:
The combustion burner is designed to serve multiple functions: (1) heating the reformer during normal operation, (2) forcing out dwelling fuel gas during stop periods to prevent oxidation, and (3) providing a transition path during fuel gas switching operations. This multi-functionality eliminates the need for dedicated inert gas feeding equipment.
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 approach effectively restrains carbon monoxide emissions at the start of power generation, maintaining catalyst integrity and improving power generation efficiency while ensuring environmental safety.
Implementation Method 1
the combustion burner (2a) combusts the supplied fuel gas containing high concentrations of carbon monoxide, thereby heating the reforming catalyst
Implementation Method 2
hydrogen-rich fuel gas is generated through the steam reforming reaction that uses water and raw material such as natural gas
Implementation Method 3
the chemical energy of fuel gas and oxidizing gas is directly converted into electric energy through a specified electrochemical reaction
Implementation Method 4
combustion by using the raw material gas supplied from the fuel cell to the combustor is performed after the switching the destination
Data Source
AI summary
A fuel cell system (100) comprising: a fuel cell (1) for generating electric power using a fuel gas; a fuel gas generator section (2) for generating the fuel gas using a raw material gas; a combustor section (2a) for generating heat energy to be used for generating the fuel gas; an air feeder section (2b) for feeding aft when the heat energy is generated; and a controller section (101); wherein the fuel cell is filled with the raw material gas before the fuel gas is fed, and wherein the controller section (101) performs a control operation such that the feed rate of air supplied from the air feeder section (2b) to the combustor section (2a) increases when the fuel gas generated in the fuel gas generator section (2) is supplied to the fuel cell (1).