Separator Tank Layout for PEM Electrolyzer Water Degassing
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Solution Overview
Problem
Existing proton exchange membrane water electrolyzers (PEMWE) face challenges with significant water crossover from the anode to the cathode, necessitating effective separation and recycling of water while minimizing dissolved hydrogen in the cathode stream.
Innovation Solution
A water treatment system incorporating an oxygen separator, hydrogen separator, and a separator tank with controlled pressure differentials and valves to separate and recycle water, reducing dissolved hydrogen and preventing gas crossover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If water is separated from the cathode stream and fed back to the anode loop in a recycling process, then water is conserved and recycling efficiency is improved, but dissolved hydrogen is carried towards the oxygen side creating a deflagration risk
Solution Approach 1:
The recycling system is divided into separate treatment streams: one for water recovery and another for hydrogen removal. The cathode stream is split where water is separated via phase separation in the separator tank, while dissolved hydrogen is removed through degassing equipment, preventing hydrogen carryover to the anode loop
Solution Approach 2:
A separator tank is introduced as an intermediary component between the cathode stream and the anode loop. This tank provides a controlled environment for phase separation and degassing, acting as a barrier that removes dissolved hydrogen before water is recycled to the anode, thus preventing hydrogen transport across the membrane
2Productivity
If a pressure gradient is maintained across the PEM, then electrochemical reaction efficiency is improved, but significant net-crossover of water from anode to cathode occurs
Solution Approach 1:
The system implements a feedback loop where water crossover is continuously monitored and the recycling rate is adjusted accordingly. Water separated from the cathode stream is fed back to the anode loop, creating a self-regulating system that compensates for pressure-driven crossover while maintaining efficient electrochemical reactions
Solution Approach 2:
Instead of discarding the water that crosses over from anode to cathode, the system recovers it through phase separation in the separator tank and feeds it back to the anode loop. This transforms a loss into a recovered resource, maintaining water balance while preserving the pressure gradient needed for reaction efficiency
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 effectively minimizes hydrogen load in the recycle stream, reduces the risk of deflagration, and ensures efficient water recycling by depressurizing and degassing before returning water to the oxygen separator.
Implementation Method 1
the hydrogen separator is adapted to operate at a first pressure and the separator tank is adapted to operate at a second pressure that is lower than the first pressure
Implementation Method 2
The separator tank is configured to receive water and dissolved hydrogen from the hydrogen separator
Implementation Method 3
Electrolyzers are known electrochemical devices that may be configured to convert electricity and water into hydrogen and oxygen
Implementation Method 4
a PEM is situated between an anode catalyst layer and a cathode catalyst layer. The PEM forms a barrier between the anode and cathode
Data Source
AI summary
A system includes at least one electrochemical device including a proton exchange membrane situated between an anode and a cathode. An oxygen separator is fluidly connected to an inlet to the anode and a hydrogen separator is fluidly connected to an outlet from the cathode. A separator tank fluidly interconnects an outlet from the hydrogen separator to an inlet to the oxygen separator.