Fuel Cell Control via O/C Ratio and Utilization Feedback
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Solution Overview
Problem
High temperature fuel cell systems face challenges in adapting quickly to internal and external changes in operating conditions, such as fuel composition variations, due to limited response times and potential loss of capacity in prior art control schemes that rely on predefined settings.
Innovation Solution
A fuel cell system with closed loop controllers that utilize fuel utilization and oxygen to carbon ratio feedback information to dynamically adjust fuel feeding and loading, implementing constraint functions to maintain optimal operating ranges, allowing for rapid responses to changes without requiring predefined parameter sets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If predefined control schemes with manual set points are used, then the system is simple to operate under stable conditions, but the response time is limited when operating conditions change
Solution Approach 1:
The patent implements feedback control by continuously measuring actual fuel utilization and oxygen-to-carbon ratio, comparing them to target values, and automatically adjusting fuel feed rate and anode recirculation flow rate. This closed-loop feedback mechanism enables the system to respond dynamically to changing operating conditions, resolving the contradiction between simple operation and fast response time.
2Productivity
If fuel feed is increased to meet higher loading demands, then productivity increases, but the oxygen to carbon ratio decreases which may cause carbon formation
Solution Approach 1:
The patent uses anode recirculation flow as an intermediary control variable to independently adjust the oxygen-to-carbon ratio without affecting productivity. By increasing anode recirculation, the system supplies additional oxygen to maintain the O/C ratio within safe limits while keeping fuel feed rate high for maximum productivity, thus preventing carbon formation.
Solution Approach 2:
The patent changes multiple operating parameters simultaneously - fuel feed rate, anode recirculation flow rate, and oxygen feed rate - to independently control both productivity and oxygen-to-carbon ratio. This multi-parameter adjustment allows the system to increase productivity while maintaining safe O/C ratios through coordinated parameter changes.
3Object-affected harmful factors
If anode recirculation is increased to maintain oxygen to carbon ratio, then carbon formation is prevented, but the fuel utilization rate decreases
Solution Approach 1:
The patent maintains continuous monitoring and adjustment of both anode recirculation flow and fuel utilization rate. By continuously optimizing the balance between these two parameters, the system prevents carbon formation while minimizing energy loss, ensuring that fuel utilization remains as high as possible at all times.
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
Enables the fuel cell system to effectively respond to changes in operating conditions, maintaining efficient operation and preventing issues like carbon formation, while ensuring stable fuel utilization and oxygen to carbon ratios, thus enhancing flexibility and reliability.
Implementation Method 1
Fuel cell device are promising future energy conversion device by means of which fuel, for example bio gas, is directly transformed to electricity via a chemical reaction
Implementation Method 2
Heat exchangers are used for controlling thermal conditions in fuel cell process and there can be located more than one of them in different locations of SOFC device
Implementation Method 3
Reformer 107 is a device that converts the fuel such as for example natural gas to a composition suitable for fuel cells, for example to a composition containing hydrogen and methane, carbondioxide, carbonmonoxide and inert gases
Data Source
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AI summary
The focus of the invention is a fuel cell system comprising fuel feeding means (116) for feeding fuel to the fuel cell system and for providing information on the fuel, means (118) for generating information about fuel utilization in the fuel cells and oxygen to carbon ratio (O/C ratio) in the fuel cell system process and active means (120) for controlling loading of the fuel cells. The fuel cell system also comprises a first closed loop controller (122) for controlling said fuel feeding means by taking into account the fuel utilization information as process feedback information, and by implementing a constraint function taking control of O/C ratio by means of restricting output of the first controller (122) when said O/C ratio deviates from an allowed range, and a second controller (124) for controlling the active fuel cell loading means (120) by implementing a constraint function taking control of fuel utilization by means of restricting output of the second controller (124) when said fuel utilization deviates from an allowed range.