Parallel Regenerable Sulfur Traps for Continuous Fuel Cell Reformate
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Solution Overview
Problem
Existing systems for desulfurizing reformate fuel streams in fuel cell systems require intermittent shutdowns for trap regeneration, leading to sulfur contamination and potential damage to active materials due to high temperatures, and involve additional heat exchanger complexity.
Innovation Solution
A system with first and second regenerable sulfur traps in parallel, connected by four-way valves, allowing continuous desulfurization and alternating regeneration to maintain a sulfur-free reformate stream, using controlled temperature and oxygen levels to protect trap materials and eliminate the need for an extra heat exchanger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sulfur trap is used for desulfurization, then the system structure is simple, but the fuel cell operation must be suspended periodically for trap regeneration
Solution Approach 1:
The single sulfur trap is divided into two separate traps (first sulfur trap and second sulfur trap) that operate in parallel. While one trap is serving the fuel cell, the other can be regenerated independently, eliminating the need to suspend fuel cell operation for regeneration and enabling continuous desulfurization.
2Productivity
If high temperature is used for trap regeneration, then sulfur removal efficiency is improved, but active materials may be damaged
Solution Approach 1:
The system alternates between two operational modes: desulfurization mode (lower temperature) and regeneration mode (higher temperature). By periodically switching between these modes using two traps, the system achieves effective sulfur removal when needed while limiting high-temperature exposure to only the regeneration phase, thereby protecting active materials from continuous thermal damage.
3Ease of repair
If intermittent shutdowns are implemented for trap regeneration, then trap maintenance is achieved, but sulfur contamination occurs and operational time is lost
Solution Approach 1:
The dual-trap system enables continuous useful action by ensuring that while one trap is being regenerated, the other trap continues to provide sulfur-free reformate to the fuel cell. This eliminates operational downtime and prevents sulfur contamination during regeneration, as the fuel cell never stops receiving desulfurized fuel.
4Temperature
If additional heat exchanger is added for temperature control during regeneration, then temperature management is improved, but system complexity increases
Solution Approach 1:
The system uses self-service temperature management by utilizing the fuel cell's own exhaust gases (cathode air and anode gas) as heating sources during trap regeneration. This eliminates the need for external heat exchangers or additional temperature control equipment, as the system recycles its own thermal energy for the regeneration process.
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 continuous supply of sulfur-free reformate to fuel cells while efficiently regenerating sulfur traps, reducing operational complexity and protecting active materials from high temperatures.
Implementation Method 1
a first regenerable trap including a trap element and, optionally, a filter element... adapted to trap sulfur and sulfur-containing compounds in a reformate stream
Implementation Method 2
an SOFC is readily fueled by 'reformate' gas, which is the effluent from a catalytic hydrocarbon oxidizing reformer
Implementation Method 3
Fuel cells for combining hydrogen and oxygen to produce electricity are well known
Data Source
AI summary
A system for removing sulfur from a continuous reformate stream feeding a fuel cell stack. First and second sulfur traps are disposed in parallel between a hydrocarbon reformer and the fuel cell stack. The ends of the sulfur traps are connected to conventional four-way valves such that either trap may be selected for trapping sulfur from the reformate stream, while the other trap is undergoing regeneration by backflushing the accumulated adsorbed sulfur deposits. Thus, the sulfur traps may be used and stripped alternately, permitting continuous supply of desulfurized reformate to the fuel cell assembly. In a currently preferred embodiment, the hot cathode air exhaust is used to assist in stripping the out-of-service trap. In an alternative embodiment, two reformers are provided and the reformers are alternately regenerated along with their respective traps.