High Temperature Fuel Cell Recirculation System
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Solution Overview
Problem
High temperature solid oxide fuel cell systems face challenges with long start-up and shutdown times, mechanical and chemical compatibility issues, and the formation of harmful carbon compounds that reduce efficiency and lifespan, due to high operating temperatures and the need for expensive purge gases.
Innovation Solution
Implementing a recirculation arrangement with a high recycle ratio of 70% or more for the anode side flow, using catalytic partial oxidation to produce hydrogen and control temperature conditions, minimizing external purge gases and water usage, and optimizing oxygen content to prevent carbon formation and maintain efficient operation during start-up and shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high operating temperature is used in solid oxide fuel cells, then energy conversion efficiency is improved, but start-up and shutdown times increase and mechanical compatibility issues worsen
Solution Approach 1:
The patent applies preliminary action by preheating the fuel cell stack using recirculated exhaust gas before正式启动 operation. The recirculation system prepares the thermal conditions in advance, allowing the stack to reach operating temperature faster and reducing overall start-up time while maintaining high efficiency operation.
2Use of energy by moving object
If high operating temperature is used in solid oxide fuel cells, then energy conversion efficiency is improved, but mechanical and chemical compatibility issues worsen
Solution Approach 1:
The patent applies parameter changes by carefully controlling the temperature profile and composition of recirculated gases to prevent thermal stress and chemical degradation. The system adjusts operational parameters to maintain temperatures that are high enough for efficient energy conversion but controlled enough to prevent material incompatibility issues.
3Object-affected harmful factors
If purge gases are used to prevent carbon formation, then harmful carbon compound formation is reduced, but system cost increases
Solution Approach 1:
The patent applies feedback by using recirculated exhaust gas that contains unreacted fuel and combustion products back to the fuel cell stack. This feedback loop maintains a reducing atmosphere that prevents carbon formation on catalyst surfaces without requiring additional purge gases, thereby reducing system costs while controlling harmful carbon compound formation.
Solution Approach 2:
The system applies self-service by utilizing its own exhaust gas for preventing carbon formation. The recirculated exhaust gas naturally provides the reducing conditions needed to protect catalysts from coking, eliminating the need for external purge gas supplies and reducing overall system complexity and cost.
4Power
If recirculation ratio is increased, then hydrogen production and temperature control are improved, but system complexity increases
Solution Approach 1:
The patent applies universality by designing the recirculation system to perform multiple functions simultaneously: it controls temperature, produces hydrogen through reforming, prevents carbon formation, and reduces the need for external purge gases. This multi-functional approach increases hydrogen production and temperature control capability without proportionally increasing system complexity.
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 reduces start-up and shutdown times, minimizes the use of expensive purge gases, and prevents carbon formation, thereby extending the service life and maintaining high efficiency of the fuel cell system while controlling thermal stresses and material selection.
Implementation Method 1
performing catalytic partial oxidation in the recirculation flow to produce an amount of hydrogen for the recirculation flow
Implementation Method 2
performing catalytic partial oxidation in the recirculation flow to produce an amount of hydrogen
Implementation Method 3
performing heat exchanging to reduce temperature conditions in the recirculation flow
Implementation Method 4
Fuel cells, by which energy of fuel, for example biogas, can be directly converted to electricity via a chemical reaction
Implementation Method 5
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, carbon dioxide, carbon monoxide and inert gases
Data Source
AI summary
An arrangement utilizing recirculation for high temperature fuel cell system, each fuel cell including an anode side, a cathode side, and an electrolyte between the anode side and the cathode side, wherein the fuel cell system can perform anode side recirculation flow of reactants. The arrangement can accomplish a recycle ratio of 70% or more for the recirculation flow, feed to the recirculation a feed-in flow, which can include substantially high oxygen content, the feed-in flow being 30% or less of entire flow, perform heat exchanging to provide substantially reduced low temperature conditions in the recirculation flow, perform catalytic partial oxidation in the recirculation flow to produce a substantially high amount of hydrogen for the recirculation flow in fuel cell system start-up or shutdown situations, and exhaust 30% or less of the entire flow from the anode side recirculation.