Sodium Chloride Production via Freezing Crystallization
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Solution Overview
Problem
Conventional sodium chloride production processes are energy-intensive and require brine purification to remove contaminants, leading to increased energy costs and scaling issues in evaporative crystallization, which reduces production capacity and efficiency.
Innovation Solution
A process involving a specific temperature lowering step to form sodium chloride dihydrate, followed by recrystallization, which reduces energy consumption and eliminates the need for brine purification, achieving higher purity sodium chloride production without scaling issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional evaporation methods are used to produce sodium chloride, then production capacity is maintained, but energy consumption is excessive
Solution Approach 1:
The patent applies phase transition by cooling brine to below 0°C to form sodium chloride dihydrate crystals through freezing, rather than using thermal evaporation. This reverses the conventional approach by utilizing冷冻 crystallization instead of evaporative crystallization, dramatically reducing energy consumption while maintaining production capacity
Solution Approach 2:
The patent changes the temperature parameter from conventional evaporation temperatures (above 0°C) to sub-zero temperatures (below 0°C), transforming the crystallization mechanism from evaporative to freezing-based. This parameter change enables the system to operate with much lower energy input while achieving the same production objective
2Manufacturing precision
If brine purification is performed to remove contaminants, then salt purity is improved, but scaling occurs in evaporators reducing production capacity
Solution Approach 1:
The patent inverts the conventional sequence by performing crystallization first to obtain pure sodium chloride dihydrate, then melting the crystals to produce anhydrous salt. This reversal eliminates the need for pre-purification steps and prevents scaling, as the crystallization process inherently separates contaminants from the product
Solution Approach 2:
The patent extracts pure sodium chloride dihydrate crystals from the brine through freezing crystallization, separating them from contaminants that remain in the mother liquor. This extraction step inherently purifies the product without requiring additional purification operations that would cause scaling
3Manufacturing precision
If brine purification is performed to remove contaminants, then salt purity is improved, but additional processing steps are required increasing complexity
Solution Approach 1:
The patent merges the purification and crystallization steps into a single freezing crystallization operation. The contaminants are automatically separated during the freezing process, eliminating the need for separate purification units and reducing overall process complexity while maintaining high salt purity
4Productivity
If evaporative crystallization is used to produce sodium chloride, then production capacity is maintained, but scaling occurs on heat exchanger surfaces
Solution Approach 1:
The patent replaces the thermal evaporation system with a freezing crystallization system. By using cooling instead of heating to achieve crystallization, the patent eliminates the heat exchangers that are prone to scaling, thereby maintaining production capacity while improving reliability
Solution Approach 2:
The patent converts the harmful effect of contaminants (which cause scaling in evaporative systems) into a benefit by using freezing crystallization. The contaminants remain in the liquid phase while pure sodium chloride dihydrate crystallizes, automatically separating impurities without causing scaling on equipment surfaces
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 process achieves lower energy consumption and higher purity sodium chloride production with reduced sludge purge and no need for brine purification, maintaining or improving salt quality compared to conventional methods while minimizing environmental impact.
Implementation Method 1
cooling the resulting brine by indirect cooling in a self-cleaning fluidized bed heat exchanger/crystallizer to a temperature lower than 0°C but higher than the eutectic temperature of the resulting brine, thereby forming a slurry comprising sodium chloride dihydrate and a mother liquor
Implementation Method 2
heating the formed sodium chloride dihydrate in a recrystallizer to melt and form anhydrous salt suspended in saturated brine
Implementation Method 3
indirect cooling in a self-cleaning fluidized bed heat exchanger/crystallizer
Data Source
Figure 1
AI summary
The present invention pertains to a process for producing sodium chloride comprising the steps of: (i) preparing a brine having a sodium chloride concentration which is higher than the sodium chloride concentration of the eutectic point but lower than the sodium chloride concentration of a saturated brine by dissolving a sodium chloride source in water; (ii) cooling the resulting brine by indirect cooling in a self-cleaning fluidized bed heat exchanger/crystallizer to a temperature lower than 00C but higher than the eutectic temperature of the resulting brine, thereby forming a slurry comprising sodium chloride dihydrate and a mother liquor; (iii) feeding the sodium chloride dihydrate to a recrystallizer to form sodium chloride and a mother liquor, and (iv) recycling at least part of the mother liquor obtained in step (ii) and/or step (iii) to step (i).