Ceramic Fiber Diaphragm Flow Control in Chlor-Alkali Cells
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Solution Overview
Problem
Electrolytic diaphragm cells in chlor-alkali electrolysis often develop perforations, leading to excessive anolyte flow into the catholyte compartment, which reduces the concentration of the principal product, increasing production costs and recycling efforts.
Innovation Solution
Introducing ceramic fibers into the anolyte compartment to reduce the flow of liquid anolyte through the diaphragm, potentially combined with halogen-containing polymer fibers and dopant materials, to mitigate the effects of perforations and maintain desired product concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the diaphragm is made microporous to allow brine flow, then brine permeability is improved, but perforations develop during electrolysis causing excessive anolyte flow
Solution Approach 1:
Ceramic fiber is introduced as an intermediary substance into the anolyte compartment that mediates the flow of brine through the diaphragm. The ceramic fiber acts as a flow restrictant that prevents excessive anolyte from passing through perforations while maintaining normal brine permeability, thus resolving the contradiction between diaphragm integrity and anolyte flow control
Solution Approach 2:
The invention changes the physical parameter of the anolyte compartment by introducing ceramic fiber material that alters the flow dynamics. This parameter change (addition of flow restrictant material) modifies the effective permeability of the system without compromising the diaphragm structure, allowing control of excessive anolyte flow while maintaining brine permeability
2Quantity of substance
If excessive anolyte flows through the diaphragm, then brine permeability is maintained, but the concentration of alkali metal hydroxide in catholyte liquor decreases
Solution Approach 1:
Ceramic fiber serves as an intermediary that selectively restricts anolyte flow while allowing necessary brine permeability. By positioning this flow restrictant in the anolyte compartment, the system maintains appropriate brine flow rates while preventing excessive anolyte from diluting the catholyte product, thus resolving the contradiction between quantity of substance and manufacturing precision
3Speed
If perforations occur in the diaphragm, then liquid flow is increased, but hypochlorite ion concentration in catholyte liquor increases
Solution Approach 1:
The ceramic fiber acts as an intermediary flow control mechanism that prevents the high-velocity liquid flow through perforations from carrying hypochlorite ions into the catholyte compartment. By moderating the flow velocity at the diaphragm interface, the system maintains liquid flow necessary for operation while preventing product contamination, resolving the contradiction between speed and manufacturing precision
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 introduction of ceramic fibers effectively increases the concentration of alkali metal hydroxide and decreases hypochlorite ion levels in the catholyte liquor, returning the electrolytic cell to desired operating conditions, thereby reducing production costs and improving product quality.
Implementation Method 1
introducing ceramic fiber into the anolyte compartment in amounts sufficient to lower the flow of liquid anolyte through the diaphragm into the catholyte compartment
Implementation Method 2
The microporous diaphragm is sufficiently porous to allow the hydrodynamic flow of brine through it
Implementation Method 3
a microporous diaphragm that separates the anolyte compartment from the catholyte compartment
Implementation Method 4
at the same time inhibiting the back migration of hydroxyl ions from the catholyte compartment into the anolyte compartment
Implementation Method 5
When direct current is applied to the cell, halogen gas is evolved at the anode, hydrogen gas is evolved at the cathode, and an aqueous alkali metal hydroxide solution is formed in the catholyte compartment
Data Source
AI summary
Describes a method for lowering the flow of liquid anolyte through perforations in the diaphragm of a diaphragm electrolytic cell, e.g., a chlor-alkali diaphragm electrolytic cell, comprising introducing ceramic fiber into the anolyte compartment of the electrolytic cell, e.g., during cell operation. The benefits described for lowering the flow of anolyte liquor through the diaphragm of a chlor-alkali diaphragm electrolytic cell are increasing the concentration of alkali metal hydroxide, e.g., sodium hydroxide, and decreasing the concentration of hypochlorite ion, e.g., sodium hypochlorite, in the catholyte liquor. Also describes introducing dopant material and/or fibers comprising halogen-containing polymer, e.g., fluorocarbon polymer fibers, into the anolyte compartment of the electrolytic cell in conjunction with the addition of ceramic fiber into the anolyte compartment, e.g., during cell operation.