Gas Diffusion Electrode Pressure Control in Brine Electrolysis
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Solution Overview
Problem
In ion exchange membrane brine electrolysis using a gas diffusion electrode, the salt concentration in the caustic soda aqueous solution increases over time, leading to electrolysis cessation.
Innovation Solution
Pressurizing the cathode gas chamber in a two-chamber ion exchange membrane electrolytic cell to reduce the salt concentration in the caustic soda aqueous solution by increasing the gas pressure, thereby maintaining a differential pressure that suppresses salt movement from the anode chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the gas diffusion electrode is intimately adhered to the ion exchange membrane to remove the cathode liquid chamber, then the electrolysis voltage is reduced to the minimum level, but the salt concentration in the caustic soda aqueous solution increases continuously
Solution Approach 1:
The invention changes the pressure parameter of the cathode gas chamber to control salt concentration. By maintaining a pressure differential between the anode and cathode chambers, the salt migration is suppressed while keeping the gas diffusion electrode in intimate contact with the ion exchange membrane for minimum electrolysis voltage.
2Power
If the cathode chamber is pressurized to realize intimate contact between the gas diffusion electrode and the ion exchange membrane, then the electric resistance is reduced to the lowest limit, but the salt concentration in the caustic soda aqueous solution reaches 100 ppm at the early stage followed by continuous upward trend
Solution Approach 1:
The invention dynamically adjusts the pressure differential between chambers during electrolysis. The cathode gas chamber pressure is maintained higher than the anode chamber pressure to suppress salt migration, while both chambers maintain the necessary pressure for intimate contact between electrodes and membrane to minimize resistance.
3Manufacturing precision
If the cathode gas chamber pressure is increased to suppress salt movement, then the salt concentration in caustic soda solution is reduced, but the differential pressure between chambers increases
Solution Approach 1:
The invention optimizes the pressure parameters by maintaining a controlled differential pressure between chambers. The cathode gas chamber pressure is kept higher to suppress salt migration, but the overall differential pressure is managed within acceptable limits to avoid excessive stress on the system components while achieving the desired salt concentration control.
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 method effectively maintains low salt concentration in the caustic soda solution without disrupting the electrolysis process, improving the quality and stability of the produced caustic soda.
Implementation Method 1
a two-chamber ion exchange membrane electrolytic cell having a gas diffusion electrode
Implementation Method 2
oxygen-containing gas (oxygen concentration is 100 % to 20 %) is supplied into the cathode chamber
Implementation Method 3
The electrolysis is carried out by feeding current between the above two electrodes
Implementation Method 4
the salt concentration in the caustic soda aqueous solution can be reduced when the electrolysis is conducted while the interior of the cathode gas chamber of the two-chamber ion exchange membrane electrolytic cell is pressurized
Data Source
AI summary
A method of electrolysis is provided in which salt concentration is reduced in a caustic soda aqueous solution produced in the two-chamber ion exchange membrane brine electrolytic cell which is divided, by means of an ion exchange membrane, into a cathode chamber equipped with a gas diffusion electrode as a cathode and an anode chamber equipped with an anode. The electrolysis is conducted while a differential pressure [a pressure obtained by subtracting an oxygen-containing gas pressure in the cathode gas chamber (measured by a manometer 18) or a gas pressure at an oxygen-containing gas inlet 14 from a liquid pressure in the anode chamber which is applied on the ion exchange membrane when the anode chamber is filled with brine (= brine height x brine density ÷ 2)] between the liquid pressure and the gas pressure in the cathode gas chamber of the two-chamber ion exchange membrane electrolytic cell 1 employing the gas diffusion electrode 7 is reduced.