Solid Oxide Fuel Cell Pre-Reformer for Hydrogen Power Modulation
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Solution Overview
Problem
Current combined hydrogen and electricity supply systems using solid oxide fuel cells have limited modulation between hydrogen and electrical power production, and are constrained by heat balance requirements, leading to restricted operating points and potential degradation of SOFC electrodes.
Innovation Solution
A method and system that utilize both external and internal steam reforming in a solid oxide fuel cell system, where a pre-reformer converts carbonaceous fuel into hydrogen and carbon monoxide, and the SOFC stack further reforms these gases to produce electricity, allowing independent thermal control of the pre-reformer and SOFC stack to adjust the ratio of hydrogen and electrical power production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If internal reforming only is used in the SOFC system, then the system structure is simplified, but the modulation between hydrogen and electrical power production is strongly limited
Solution Approach 1:
The reforming process is segmented into two independent stages: external reforming in a pre-reformer unit and internal reforming in the SOFC stack. This segmentation allows independent control of each reforming stage, enabling flexible modulation between hydrogen production and electrical power generation by adjusting the operating parameters of the pre-reformer and SOFC stack separately
2Quantity of substance
If the SOFC stack operates close to short-circuit to maximize hydrogen production, then hydrogen output is increased, but strong degradation of the SOFC electrodes occurs
Solution Approach 1:
The pre-reformer performs preliminary reforming of the carbonaceous fuel before it enters the SOFC stack. This preliminary action converts a significant portion of the fuel to hydrogen and carbon monoxide externally, allowing the SOFC stack to operate at optimized conditions rather than extreme conditions, thereby preventing electrode degradation while maintaining high hydrogen production
3Adaptability or versatility
If external reforming is added to the SOFC system, then modulation between hydrogen and electrical power is improved, but the device complexity increases
Solution Approach 1:
The pre-reformer is thermally coupled to the SOFC stack, allowing the SOFC stack to provide heat for the endothermic reforming reactions in the pre-reformer. This self-service arrangement reduces the need for external heating systems and other auxiliary equipment, thereby limiting the increase in device complexity while enabling flexible modulation between hydrogen and electrical power production
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 flexible and efficient co-production of hydrogen and electricity over a wide range of operating conditions, reducing the risk of SOFC electrode degradation and expanding the system's operational flexibility.
Implementation Method 1
introducing a carbonaceous fuel and steam into a pre-reformer, and in the pre-reformer reforming part of the carbonaceous fuel by steam reforming into a first reformate gas comprising hydrogen and carbon monoxide
Implementation Method 2
in the solid oxide fuel cell stack converting oxygen as well as hydrogen and carbon monoxide of the first and second reformate gas into electrical power and an anode off-gas
Implementation Method 3
in the solid oxide fuel cell stack reforming at least part of the unconverted carbonaceous fuel and preferably all of the unconverted carbonaceous fuel by steam reforming into a second reformate gas comprising mainly hydrogen and carbon monoxide
Implementation Method 4
introducing the anode off-gas into a H2 separation unit, converting in the H2 separation unit the anode off-gas into purified hydrogen and an off-gas
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A combined hydrogen and electricity supply system (1) for producing hydrogen (80), electrical Power (P) and co-production, the system comprising a variable electrical load (6) for varying the amount of impedance on the system, a pre-reformer (3) connected to a stream of carbonaceous fuel (20), a stream of steam (40) and connected to a heating source (9), wherein said pre-reformer (3) produces a first reformate gas comprising at least hydrogen, carbon monoxide and unconverted carbonaceous fuel, wherein the pre-reformer (3) is responsive to the amount of heat provided by the heating source, a solid oxide fuel cell stack (2) coupled to the variable electrical load (6) and coupled to the first reformate gas, wherein the ratio between electrical power (P) and amount of hydrogen (80) produced depends at least on the variable electrical load (6) and the heat provided by the heating source (9).