Fuel Cell System with Molten Carbonate Electrolyzer for Hydrogen Recycling
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Solution Overview
Problem
Fuel cell systems face inefficiencies due to the export of anode exhaust containing carbon dioxide and water, which are not fully utilized for power generation, leading to energy losses and reduced electrical efficiency.
Innovation Solution
A fuel cell system incorporating a high temperature hydrogen purification system, specifically a molten carbonate electrolyzer, recycles anode exhaust to produce a hydrogen stream with over 70% purity, minimizing carbon dioxide and water, and utilizing an anode gas oxidizer to recover heat and prevent inert buildup, thereby increasing overall electrical power generation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anode exhaust is exported to prevent excessive buildup of carbon dioxide and water, then carbon dioxide and water accumulation is controlled, but electrical efficiency decreases due to loss of usable hydrogen
Solution Approach 1:
The patent extracts and removes carbon dioxide and water from the anode exhaust stream using a purification system, separating these components from the hydrogen-rich gas. This allows the hydrogen to be recycled while the carbon dioxide and water are selectively removed and discharged, resolving the contradiction between controlling accumulation and maintaining efficiency.
Solution Approach 2:
The patent recovers hydrogen from the anode exhaust by removing carbon dioxide and water, then recycles the purified hydrogen back to the fuel cell anode. This recovery process prevents loss of usable fuel while still allowing controlled discharge of carbon dioxide and water, thereby improving electrical efficiency without compromising reliability.
2Productivity
If carbon dioxide and water are removed from anode exhaust to enable full recycling, then electrical efficiency increases, but energy losses occur due to heat exchanger temperature approaches
Solution Approach 1:
The patent performs carbon dioxide and water removal at high temperature within the purification system, minimizing energy losses due to heat exchanger temperature approaches. By maintaining high temperature throughout the purification and recycling process, the system avoids the thermal efficiency penalties that would occur with conventional cooling and reheating approaches.
3Productivity
If additional anode exhaust is recycled through purification, then overall electric power generation increases, but power is required to drive the purification system
Solution Approach 1:
The purification system is integrated into the fuel cell loop such that the power required to drive the purification process is provided by the fuel cell itself. The fuel cell generates electricity that powers the carbon dioxide and water removal system, enabling autonomous operation without external power input while still achieving net efficiency gains through hydrogen recycling.
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
The system achieves electrical efficiency greater than 70% by recycling hydrogen and minimizing energy losses, with the power needed to drive the purification system offset by additional hydrogen production, allowing for scalable and efficient power generation with zero water consumption.
Implementation Method 1
The electrolyte layer serves to transfer ions between the anode and the cathode, which facilitate reactions within the anode and the cathode to generate electrons for the production of electricity
Implementation Method 2
The anode of the electrolyzer cell may be configured to receive a first portion of the anode exhaust stream and another portion of the hydrocarbon feed, and to generate a hydrogen stream
Implementation Method 3
a heat exchanger configured to receive an air stream and the oxidized exhaust, and to transfer heat from the oxidized exhaust to the air stream
Implementation Method 4
an anode gas oxidizer configured to oxidize a gas stream to remove carbon dioxide and nitrogen therefrom and to output an oxidized exhaust
Implementation Method 5
Fuel cells are devices that are capable of converting chemical energy stored in a fuel, such as a hydrocarbon fuel, into electrical energy through electrochemical reactions
Data Source
AI summary
A fuel cell system includes a fuel cell having a cathode and an anode configured to receive a portion of a hhydrocarbon feed and to output an anode exhaust stream comprising carbon dioxide, hydrogen, and water; and an electrolyzer cell having a cathode and an anode. The anode of the electrolyzer cell is configured to receive a first portion of the anode exhaust stream and another portion of the hydrocarbon feed, and to generate a hydrogen stream.