Dialytic Stack Desalination Using Concentration Gradient Energy
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Solution Overview
Problem
Current desalination methods, such as reverse osmosis, multiple effect distillation, and electrodialysis, face challenges including high energy consumption, scaling issues with ion exchange membranes, and the production of brine that is environmentally problematic, which limits their efficiency and effectiveness in providing freshwater from saltwater sources.
Innovation Solution
A method and system utilizing a dialytic stack that leverages concentration difference energy to desalinate saltwater by generating a drive voltage through a concentrate and diluent solution flow, allowing ions to migrate across exchange membranes, thereby reducing the salt concentration and managing brine output efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If reverse osmosis is used to desalinate saltwater, then freshwater can be produced, but high energy consumption and extensive pre-treatment are required
Solution Approach 1:
The patent employs concentration difference energy from the brine stream itself to drive the desalination process. The high-concentration brine naturally generates electrical potential that is used to power ion migration through membranes, eliminating the need for external high-pressure pumps and reducing energy consumption.
Solution Approach 2:
The invention replaces the mechanical high-pressure system of reverse osmosis with an electrochemical system. Instead of using mechanical pressure to force water through membranes, the system uses electrical potential generated from concentration differences to drive ion removal, substituting mechanical energy with electrochemical energy.
2Quantity of substance
If electrodialysis is used to desalinate saltwater, then freshwater can be produced, but ion exchange membranes accumulate scaling over time
Solution Approach 1:
The patent implements periodic reversal of the electrical field direction to prevent scaling accumulation on membranes. By alternating the polarity, ions are periodically removed from both sides of the membranes, preventing the buildup of scale deposits that would occur with continuous unidirectional operation.
Solution Approach 2:
The system uses the concentration difference energy from the brine stream to generate the electrical potential needed for ion removal. This self-powered approach eliminates the need for external power sources and reduces the conditions that lead to scaling, as the natural concentration gradient drives the process without requiring high external voltages.
3Quantity of substance
If multiple effect distillation or multi-stage flash is used to desalinate saltwater, then freshwater can be produced, but large amounts of thermal energy are consumed
Solution Approach 1:
The invention replaces thermal energy-based distillation processes with an electrochemical process. Instead of using heat to evaporate and condense water, the system uses electrical potential generated from concentration differences to drive ion migration, substituting thermal energy with electrochemical energy.
Solution Approach 2:
The patent changes the fundamental operating parameter from thermal energy to electrochemical energy. By utilizing the electrical potential generated from concentration differences, the system operates in a different energy regime that avoids the high thermal energy requirements of distillation processes.
4Quantity of substance
If conventional desalination methods are used, then freshwater can be produced, but brine with high salt concentration and large volume is discharged
Solution Approach 1:
The system uses the concentration difference energy from the brine stream itself to drive the desalination process. The brine's high concentration naturally generates electrical potential that is harnessed to power ion migration, turning the potentially harmful waste stream into a useful energy source that simultaneously reduces brine volume and concentration.
Solution Approach 2:
The patent converts the harmful high-concentration brine stream into a beneficial energy source. The concentration gradient in the brine, which would normally be a waste product, is used to generate electrical potential that drives the desalination process, thereby reducing both the volume and concentration of the final brine discharge.
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 enables a high recovery ratio of freshwater production with reduced brine volume and concentration, lowering energy consumption and mitigating scaling issues, thus improving the economic and environmental sustainability of desalination processes.
Implementation Method 1
utilizing a dialytic stack designed to desalinate saltwater at a relatively high recovery ratio
Implementation Method 2
flowing a diluent solution having an ionic concentration lower than an ionic concentration of the concentrate solution through a diluent chamber, the concentrate and diluent chambers forming a drive cell and sharing one of an anion and cation exchange membrane such that anions or cations flow from the concentrate chamber to the diluent chamber through the exchange membrane
Implementation Method 3
applying a sufficient voltage that comprises the drive voltage across a first product chamber through which flows the saltwater to be desalinated and that is in ionic communication with the drive cell. The sufficient voltage equals or exceeds a desalination voltage of the first product chamber such that cations and anions respectively migrate from the first product chamber
Data Source
AI summary
Described herein are a method and system for desalinating saltwater using concentration difference energy. A “five stream” dialytic stack is described that can be used to desalinate saltwater at a relatively high recovery ratio. The dialytic stack may include, for example, one or more drive cells having a paired concentrate and a diluent-c chamber in ionic communication with a product chamber that is adjacent to an anion and a cation discharge chamber each filled with diluent-p. The drive cell applies a drive voltage across the product chamber, and when the drive voltage exceeds a desalination voltage of the product chamber, the saltwater in the product chamber is desalinated. The dialytic stack may accept brine discharged from a first desalination plant as saltwater to be desalinated. Processing the brine in the dialytic stack may decrease its volume, decreasing costs associated with treating or otherwise disposing of the brine.