Pressurized Solid Oxide Cell Stack Sealing Without External Vessels
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Solution Overview
Problem
Existing electrochemical cell stacks face challenges in operating efficiently at pressures above atmospheric conditions without requiring external pressure vessels, which are costly and impractical due to system constraints and potential damage from unbalanced fuel and air pressures.
Innovation Solution
The design of internally pressurized electrochemical cell stacks with integrated seals and interconnects that allow operation at pressures above atmospheric conditions, using fuel and air channels within the stack to balance internal pressures without external vessels, and employing specific seal materials and configurations to prevent fuel and air leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If external pressure vessels are used to operate electrochemical cell stacks at elevated pressures, then the stack can operate at pressures above atmospheric conditions, but the system becomes more costly and complex due to the additional external pressure vessel requirement
Solution Approach 1:
The patent integrates the pressure-containing function directly into the cell stack structure by using seals between adjacent cell units and interconnects, merging the reactor vessel and pressure containment functions into a single integrated structure, thereby eliminating the need for separate external pressure vessels
Solution Approach 2:
The cell stack structure itself provides the pressure containment function through its own seals and interconnect design, making the system self-sufficient for pressure management without requiring external pressure vessels or additional containment structures
2Stress or pressure
If external pressure vessels are used to contain the electrochemical cell stack, then elevated pressure operation is enabled, but the cost of the system increases due to the additional pressure vessel component
Solution Approach 1:
The pressure containment function is merged into the cell stack structure itself through the seal and interconnect design, eliminating the need for separate pressure vessels and reducing overall system cost
Solution Approach 2:
The external pressure vessel is extracted from the system by redistributing the pressure containment function to individual cell units and interconnects, thereby removing the costly external pressure vessel component while maintaining elevated pressure operation capability
3Productivity
If unbalanced fuel and air pressures are applied to the electrochemical cell stack, then the electrochemical reactions can proceed, but component damage may occur due to excessive stress on the cell structure
Solution Approach 1:
The seal design provides localized pressure management at each cell unit interface, allowing different pressures in fuel and air channels while distributing mechanical stress locally rather than concentrating it on the entire cell structure
Solution Approach 2:
The cell stack is segmented into multiple cell units with individual seals and interconnects, allowing independent pressure management for fuel and air sides while distributing mechanical loads across multiple localized seal interfaces, preventing catastrophic failure
4Reliability
If seals are added to prevent fuel and air leakage in pressurized operation, then pressure containment is improved, but the device complexity increases due to additional seal components
Solution Approach 1:
The seal function is merged into the interconnect structure itself, where the interconnect serves both as an electrical/structural connector and as a pressure barrier through integrated sealing features, reducing the need for separate seal components
Solution Approach 2:
The interconnect is designed to perform multiple functions simultaneously: electrical connection, structural support, and pressure containment through integrated seals, thereby reducing overall component count while maintaining reliable pressure containment
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 efficient operation of electrochemical cell stacks at elevated pressures, reducing the need for external pressure vessels and minimizing the risk of component damage, while enhancing reaction kinetics and power density.
Implementation Method 1
a solid oxide electrolyte located between the fuel electrode and the air electrode
Implementation Method 2
sintering the stack to compress the ring seals, such that the interconnects are supported by the pressure seals
Implementation Method 3
applying a compressive load to the stack to compress the pressure seals, such that the interconnects apply a first load to the electrochemical cells
Data Source
AI summary
A method of operating a solid oxide electrolyzer cell stack includes providing steam into a fuel internal riser extending through the solid oxide electrolyzer cell stack at a pressure of at least 15 psig, and electrolyzing the steam in the solid oxide electrolyzer cell stack to generate a hydrogen containing product stream at a pressure of at least 15 psig.