Ion Exchange Membrane Electrolyzer Reverse Current Prevention
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Solution Overview
Problem
Existing methods for preventing reverse current flow in ion exchange membrane electrolyzers are inadequate, particularly when the system is stopped, leading to performance degradation and potential explosive gas mixtures due to hydrogen and oxygen generation.
Innovation Solution
Injecting a low electrical conductivity material, such as water or inert gases, into the anode and cathode solution-supplying pipes after stopping the electrolyzer operation to increase electrical resistance and terminate cathode solution circulation, while electrically insulating one cathode solution pathway from another to reduce reverse current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brine is injected into the anode chamber to eliminate active material and reduce electromotive force, then reverse current is reduced, but the system requires additional injection equipment and operational steps
Solution Approach 1:
The patent extracts the harmful active materials (chlorine and hydrogen) from the electrolyzer chambers by flushing them out with fresh electrolyte solution after shutdown. This eliminates the source of reverse current electromotive force without requiring complex injection systems, as the flushing uses the existing circulation system.
Solution Approach 2:
The patent changes the composition parameter of the electrolyte by introducing fresh electrolyte solution to replace the spent electrolyte containing active materials. This parameter change (electrolyte composition) directly reduces the electromotive force that drives reverse current.
2Productivity
If the electrolyzer operates at high temperature to improve efficiency, then productivity increases, but the electromotive force for reverse current generation is enhanced
Solution Approach 1:
The patent performs preliminary flushing of the electrolyzer chambers with fresh electrolyte immediately after shutdown, before reverse current can significantly develop. This preliminary action removes active materials and cools the electrolyte, preventing the temperature-related enhancement of reverse current electromotive force.
Solution Approach 2:
The patent converts the harmful high temperature condition that enhances reverse current into a benefit by using the temperature difference to drive convection currents that aid in flushing out active materials. The cooling process itself becomes part of the solution to eliminate reverse current sources.
3Reliability
If a protective current is applied from anode to cathode to prevent reverse current, then reverse current flow is prevented, but hydrogen gas is produced in the cathode chamber which may diffuse through the membrane and create explosive mixtures
Solution Approach 1:
Instead of applying protective current from anode to cathode (conventional direction), the patent flushes both chambers with fresh electrolyte to eliminate active materials, thereby eliminating the need for protective current and the associated hydrogen production risk. This inverts the approach from active protection to passive elimination.
Solution Approach 2:
The patent extracts active materials (chlorine from anode chamber, hydrogen from cathode chamber) by flushing with fresh electrolyte, removing the chemical basis for reverse current generation without requiring protective current that would produce additional hydrogen.
4Speed
If cathode solution circulation is continued after shutdown to maintain system readiness, then quick restart is enabled, but reverse current flows through the circulation system causing performance degradation
Solution Approach 1:
The patent performs preliminary flushing of the cathode solution circulation system with fresh electrolyte after shutdown, eliminating active materials before they can generate significant reverse current. This allows the circulation system to be restarted quickly without having dealt with active materials that would cause performance degradation.
Solution Approach 2:
The patent uses fresh electrolyte solution as an intermediary substance to replace the spent cathode solution containing active materials. This intermediary flushing process eliminates reverse current sources while maintaining system readiness for quick restart.
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
Effectively prevents reverse current flow by reducing electromotive force and electrical conductivity, thereby minimizing performance degradation and safety risks associated with gas mixtures.
Implementation Method 1
Injecting a low electrical conductivity material, such as water or inert gases, into the anode and cathode solution-supplying pipes after stopping the electrolyzer operation to increase electrical resistance
Implementation Method 2
a bipolar-type ion exchange membrane electrolyzer, in which bipolar elements each integrating with an anode chamber harboring an anode on one surface and a cathode chamber harboring a cathode on the other surface are arranged side by side with an ion exchange membrane interposed between the bipolar elements
Implementation Method 3
In the electrolysis of brine, for example, an electromotive force is induced across an intervening ion exchange membrane
Data Source
AI summary
Provided is a method of preventing reverse current flow through an ion exchange membrane electrolyzer, which method is capable of preventing a reverse current from being generated after stopping operation of the ion exchange membrane electrolyzer.A method of preventing reverse current flow through an ion exchange membrane electrolyzer 100, the ion exchange membrane electrolyzer 100 having an anode chamber 107 housing an anode, a cathode chamber 110 housing a cathode, an anode solution-supplying manifold 121 to feed anode solution to the anode chamber 107, and a cathode solution-supplying manifold 124 to feed cathode solution to the cathode chamber 110. After stopping operation of the ion exchange membrane electrolyzer 100, injected is a low electrical conductivity material with an electrical conductivity lower than that of the anode solution or the cathode solution to at least one of an anode solution-supplying pipe 127 which supplies the anode solution to the anode solution-supplying manifold 121 from an anode solution tank 123 and a cathode solution-supplying pipe 128 which supplies the cathode solution to the cathode solution-supplying manifold 124 from a cathode solution tank 123.