Electrodialysis Chloride Ion Recovery in Nuclear Reprocessing
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Solution Overview
Problem
Current methods for recirculating reprocessing effluent from ion exchange resins are inefficient in recovering chloride ions and water, leading to high energy consumption and pollutant discharge, particularly in the concentration of chloride ions from diluted fractions which requires costly evaporation techniques.
Innovation Solution
The method involves selecting fractions with varying chloride ion concentrations and using electrodialysis to transfer chloride ions from less concentrated to more concentrated fractions, thereby enriching the chloride ion concentration, and optionally combining with nanofiltration and reverse osmosis steps to maximize chloride recovery and minimize energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If evaporation techniques are used to concentrate chloride ions from diluted fractions, then chloride ion concentration is improved, but energy consumption increases significantly
Solution Approach 1:
The patent replaces thermal evaporation (heat-based mechanical system) with electrodialysis (electrical system) for concentrating chloride ions. The electrodialysis unit uses electric current to drive ion exchange membranes that selectively transport chloride ions from diluted fractions to concentrate them, eliminating the high energy consumption associated with evaporation while achieving the same concentration effect
Solution Approach 2:
The patent changes the concentration parameter of chloride ions by using electrodialysis to transfer ions between compartments. By applying electrical potential and using selective ion exchange membranes, the system dynamically adjusts chloride ion concentration from diluted fractions (e.g., 5-20 g/L) to concentrated form (e.g., 80-100 g/L) without thermal energy input
2Manufacturing precision
If nanofiltration is applied to separate coloring agents from salt, then separation efficiency is improved, but chloride ion recovery is reduced due to dilution
Solution Approach 1:
The patent extracts only the necessary function (coloring agent removal) using nanofiltration while preserving the chloride ions in the permeate. The nanofiltration membrane selectively retains macromolecular coloring agents while allowing small chloride ions to pass through, separating the harmful component while recovering the valuable salt for reuse in reprocessing
Solution Approach 2:
The patent discards the coloring agents retained by the nanofiltration membrane while recovering the chloride-rich permeate for reuse. The separated permeate containing concentrated chloride ions is fed back to the electrodialysis unit or directly reused as reprocessing brine, minimizing salt loss and maximizing resource efficiency
3Object-generated harmful factors
If diluted fractions of reprocessing effluent are discarded, then pollutant discharge is reduced, but water recycling is minimized
Solution Approach 1:
The patent establishes a continuous recycling loop where diluted fractions are not discarded but continuously fed into the electrodialysis unit for chloride ion concentration. The system maintains continuous operation by constantly processing diluted effluent, concentrating chloride ions, and returning them to the reprocessing circuit, eliminating discharge while maximizing water and salt reuse
Solution Approach 2:
The system makes the diluted fractions serve a useful function by using them as feed material for the electrodialysis unit. Rather than being waste, the diluted fractions provide the chloride ions that need to be concentrated, transforming a disposal problem into a resource recovery opportunity
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
This approach effectively recovers a high concentration of chloride ions with reduced energy consumption, minimizing the volume of pollutant effluents and optimizing water recycling, while avoiding the costly evaporation processes.
Implementation Method 1
using electrodialysis to transfer chloride ions from less concentrated to more concentrated fractions
Implementation Method 2
Transferring by electrodialysis the chloride ions of the fraction B to the fraction A
Implementation Method 3
the separation of both of these species by applying a nanofiltration membrane is quite easy
Implementation Method 4
Because of the difference in size between the salt, i.e. the chloride ions, and the macromolecules which the coloring agents are
Implementation Method 5
optionally combining with nanofiltration and reverse osmosis steps to maximize chloride recovery
Data Source
AI summary
The object of the present invention is a method for recirculating a reprocessing effluent comprising chloride ions from an ion exchange resin comprising the following steps:(ii) selecting fractions A, B, and optionally B′, directly stemming from a reprocessing effluent comprising chloride ions or after one or several steps for modifying the chloride ion concentration, having concentrations of chloride ions (g/l) of respectively (a), (b) and (b′)>0 g/l, with (a)>(b);(iii) transferring by electrodialysis the chloride ions from the fraction B to fraction A for obtaining a fraction C having a chloride ion concentration (c) greater than (a); or(iv) transferring by electrodialysis the chloride ions from fraction B to fraction B′, in order to obtain a fraction B″ having a concentration of chloride ions (b″) greater than (b′) and then mixing the fractions B″ and A in order to obtain a fraction C having a chloride ion concentration (c) greater than (a).