Diaphragm Electrolytic Cell Anolyte Flow Control
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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 dilutes the concentration of the principal product, increasing production costs and recycling requirements.
Innovation Solution
Introducing ceramic fibers and halogen-containing polymer fibers into the anolyte compartment to reduce the flow of anolyte through the diaphragm, thereby maintaining desired product concentrations by regulating microporosity and enhancing the diaphragm's resistance to corrosive conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the diaphragm is made microporous to allow brine flow, then hydrodynamic flow of brine is enabled, but perforations develop leading to excessive anolyte flow into catholyte compartment
Solution Approach 1:
The patent uses a microporous diaphragm made of porous ceramic material that allows controlled hydrodynamic flow of brine while maintaining structural integrity. The porous structure enables ion and fluid transport necessary for electrolysis while preventing perforation-induced leakage.
Solution Approach 2:
The diaphragm is constructed as a composite structure combining porous ceramic material with appropriate binders or coatings that enhance mechanical strength and corrosion resistance. This composite approach allows the diaphragm to withstand operational stresses without developing perforations while maintaining its microporous flow characteristics.
2Productivity
If too high flow of anolyte through diaphragm occurs, then electrolysis continues, but concentration of alkali metal hydroxide in catholyte compartment decreases
Solution Approach 1:
The patent implements monitoring and control mechanisms that track the flow rate of anolyte through the diaphragm and the concentration of products in the catholyte compartment. When deviations are detected, operational parameters are adjusted to maintain optimal flow rates and product concentrations, preventing excessive dilution while sustaining productivity.
Solution Approach 2:
The patent optimizes operational parameters including applied current density, brine flow rate, and diaphragm pore size to achieve the desired balance between electrolysis productivity and product concentration. By carefully controlling these parameters, the system maintains high production rates while preventing excessive anolyte leakage that would dilute the catholyte product.
3Quantity of substance
If ceramic fibers and halogen-containing polymer fibers are introduced into anolyte compartment, then anolyte flow through diaphragm is reduced, but device complexity increases
Solution Approach 1:
The patent introduces ceramic fibers and halogen-containing polymer fibers as intermediary materials within the anolyte compartment. These fibers act as flow regulators that intercept and redirect anolyte flow, preventing excessive penetration through the diaphragm. The fibers are suspended in the electrolyte solution and do not require complex installation structures, thereby limiting the increase in device complexity.
Solution Approach 2:
The ceramic and halogen-containing polymer fibers possess porous structures that facilitate controlled fluid interaction. These porous materials allow the fibers to absorb and release electrolyte while providing resistance to bulk flow, effectively reducing anolyte penetration through the diaphragm without requiring complex structural modifications to the cell.
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 and halogen-containing polymer fibers effectively reduces anolyte flow, restoring optimal alkali metal hydroxide concentrations and decreasing hypochlorite ion levels, thus improving operational efficiency and reducing process costs by maintaining desired product concentrations.
Implementation Method 1
The microporous diaphragm is sufficiently porous to allow the hydrodynamic flow of brine through it, while at the same time inhibiting the back migration of hydroxyl ions from the catholyte compartment into the anolyte compartment
Implementation Method 2
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.