Halogen Salt Purification via Active Metal Contact
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Solution Overview
Problem
Existing methods are inadequate for reducing impurities in halogen salts from about 1% by weight to ≤0.05% by weight, which is necessary for safe and efficient operation in high-temperature applications such as thermal power plants and batteries.
Innovation Solution
Contacting halogen salts with a liquid active metal in an inert atmosphere at a temperature above the melting point of both the active metal and the halogen salt, allowing impurities to react with the active metal and be separated, thereby reducing impurity levels to 0.05% by weight or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If halogen salts are used as high-temperature heat storage materials, then thermal stability is improved, but corrosivity increases due to impurities
Solution Approach 1:
The patent extracts harmful impurities (hydroxides, water, oxygen) from halogen salts through a multi-step purification process involving heating, sparging with inert gas, and filtration. This removal of impurities eliminates the source of corrosivity while preserving the high thermal stability of the halogen salts, enabling their use as heat storage materials at temperatures above 560°C.
Solution Approach 2:
The patent applies preliminary purification actions to halogen salts before they are used as heat storage materials. The process includes pre-heating to remove moisture, sparging with inert gas to remove oxygen and hydroxides, and filtration to remove particulates. This preliminary treatment prevents corrosivity from developing during subsequent high-temperature operation.
2Productivity
If heating rate is increased to improve efficiency, then energy transfer is improved, but thermal decomposition increases
Solution Approach 1:
The patent changes the chemical composition parameters of the halogen salt mixture by removing impurities (water, hydroxides, oxygen) through controlled heating and sparging. This parameter change lowers the decomposition temperature threshold and allows safer, more efficient heating rates during thermal energy storage and transfer operations, as the purified salt is more resistant to thermal decomposition.
3Duration of action of stationary object
If impurity content is reduced to increase service life, then corrosivity is reduced, but processing complexity increases
Solution Approach 1:
The patent implements a continuous purification process where halogen salts are heated, sparged with inert gas, and filtered in a continuous sequence rather than discrete batch operations. This continuous action efficiently removes impurities to extend service life while maintaining relatively simple processing equipment and操作流程, making the complexity manageable.
4Manufacturing precision
If purification is intensified to reduce impurities from 1% to ≤0.05%, then corrosivity is reduced, but energy consumption increases
Solution Approach 1:
The patent uses a composite approach combining multiple purification mechanisms (thermal heating, inert gas sparging, filtration) in sequence. Each mechanism targets specific impurity types, achieving cumulative purification from 1% to ≤0.05% impurity content. This composite method distributes energy consumption across different stages rather than requiring extreme conditions in a single step, making the intensive purification more energy-efficient.
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 method effectively reduces the impurity content of halogen salts to the required low levels, significantly reducing corrosivity and enhancing the suitability of halogen salts for high-temperature applications.
Implementation Method 1
contacting said halogen salt or halogen salt mixture with said active metal in an inert atmosphere at a temperature that is above the melting temperature of said active metal, whereby impurities in said halogen salt or halogen salt mixture react with said active metal
Implementation Method 2
said active metal is selected to be immiscible with the molten halogen salts, have a density different from that of the purified halogen salt
Data Source
AI summary
Processes and devices for reducing impurities in halogen salts, where the halogen salt is brought into contact with an active metal. The halogen salts purified in this way are suitable for use as high-temperature storage materials in thermal power plants and for industrial process heat, or as electrolytes in batteries.