Solid Oxide Fuel Cell Startup CO Suppression
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Solution Overview
Problem
Conventional solid oxide fuel cell (SOFC) systems face challenges in suppressing the generation of carbon monoxide during startup, as existing ignition methods do not effectively control the supply of reforming air, leading to instability and increased carbon monoxide production.
Innovation Solution
The SOFC system employs a controlled sequence of raw material and electric power generation air supply, where the reforming air is introduced only after ignition, and the flow rate is managed to prevent premature mixing, thereby stabilizing the flame and reducing carbon monoxide generation. Additionally, a temperature-controlled exhaust gas purifying system ensures efficient removal of carbon monoxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reforming air is supplied during ignition, then the combustion process can be sustained, but carbon monoxide generation increases and ignition stability deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-heating the reforming air to a high temperature (800-1000°C) before introducing it to the combustor during ignition. This pre-heating prepares the air in advance to provide sufficient heat for stable combustion without requiring additional reforming air flow that would cause CO generation and instability.
Solution Approach 2:
The patent changes the temperature parameter of the reforming air from ambient temperature to high temperature (800-1000°C) through pre-heating. This parameter change allows the reforming air to serve dual purposes: providing oxygen for combustion while simultaneously providing heat for stable flame maintenance, thereby eliminating the need for excessive reforming air flow that would cause CO generation.
2Reliability
If additional heating sources are used during startup, then ignition reliability can be improved, but system complexity and cost increase
Solution Approach 1:
The patent applies multi-functionality by making the reforming air serve multiple purposes: it provides oxygen for combustion, provides heat through pre-heating for flame stabilization, and eliminates the need for separate heating sources. The exhaust gas from the fuel cell stack is utilized to pre-heat the reforming air, creating a self-sustaining system that reduces complexity.
Solution Approach 2:
The system applies self-service by using its own exhaust gas to pre-heat the reforming air during startup. The heat that would otherwise be wasted in the exhaust gas is recovered and used to prepare the reforming air, making the system self-sufficient and eliminating the need for external heating sources or additional energy input.
3Object-generated harmful factors
If reforming air flow rate is increased during operation, then carbon monoxide can be suppressed, but energy efficiency decreases
Solution Approach 1:
The patent changes the temperature parameter of the reforming air from ambient to high temperature (800-1000°C) through pre-heating. This parameter change increases the energy content of each unit of reforming air, allowing CO suppression with lower flow rates and maintaining energy efficiency.
Solution Approach 2:
The patent converts the harmful hot exhaust gas that would be wasted into a beneficial heating source for the reforming air. The exhaust gas heat is utilized to pre-heat the reforming air, and this same pre-heated air then suppresses CO generation in the combustor, turning a potential waste stream into a solution for the CO problem while maintaining energy efficiency.
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 suppresses carbon monoxide generation during startup and operation, enhancing ignition stability and reducing harmful emissions, while eliminating the need for additional heating sources.
Implementation Method 1
an igniting portion configured to ignite the raw material when starting up the solid oxide fuel cell system
Implementation Method 2
a reformer portion configured to reform the raw material to generate the reformed gas
Implementation Method 3
a fuel cell module including a fuel cell stack configured to cause a reaction between a reformed gas and electric power generation air to generate electric power
Implementation Method 4
an exhaust gas purifying portion configured to purify a flue gas generated by the combustion in the combustor
Data Source
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AI summary
A solid oxide fuel cell system includes: an igniting portion configured to ignite a raw material when starting up the solid oxide fuel cell system; a water supply portion configured to supply reforming water to the reformer portion; an exhaust gas purifying portion configured to purify a flue gas generated by the combustion in the combustor; a flow rate controller configured to control flow rates of the raw material, the reforming air, the electric power generation air, and the reforming water; and a purifying portion temperature detector provided at an inlet of the exhaust gas purifying portion and configured to detect a temperature of the inlet of the exhaust gas purifying portion, wherein after the temperature of the inlet of the exhaust gas purifying portion detected by the purifying portion temperature detector becomes a predetermined temperature after the ignition, the water supply portion and the flow rate controller supplies the reforming water or increases the flow rate of the reforming water.