Continuous Salt Crystallization with Decanter Separation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing crystallization processes for salt solutions are limited in controlling crystal size, require expensive settling zones, and cannot separate the heavier-boiling liquid component from crystals, making it difficult to adjust residence times and lead to fluctuations in crystal size due to metastable supersaturation.
Innovation Solution
A continuous process where the lower-boiling liquid components are evaporated in a forced circulation evaporator, with crystals collected at the bottom and separated from the solution using a decanter in the circulation line, allowing independent adjustment of residence times and crystal size, and enabling separate treatment of the heavier-boiling liquid phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If settling zones are installed inside the evaporator to collect crystal nuclei, then crystal size can be controlled, but the equipment becomes expensive and difficult to clean
Solution Approach 1:
The patent extracts the settling function from the evaporator by installing a separate decanter in the circulation line. The decanter collects crystal nuclei while the evaporator focuses on evaporation and crystallization. This separation eliminates the need for complex internal settling zones in the evaporator, making it easier to clean and maintain while still achieving crystal size control.
Solution Approach 2:
The decanter acts as an intermediary device between the evaporator and the pump. It receives the suspension from the evaporator, separates crystal nuclei through settling, and returns the clarified solution to the evaporator. This intermediary component enables crystal size control without modifying the evaporator's internal structure.
2Manufacturing precision
If the salt solution is circulated through a heat exchanger to dissolve crystal nuclei, then nucleation can be controlled, but the residence time of liquid and crystals cannot be adjusted independently
Solution Approach 1:
The patent segments the circulation system into distinct functional zones: the evaporator for evaporation and crystallization, the decanter for crystal nuclei separation, and the heat exchanger for dissolving nuclei. This segmentation allows independent control of residence times - crystals settle in the decanter while the liquid phase continues circulation through the heat exchanger, enabling separate adjustment of their residence times.
Solution Approach 2:
The decanter serves as an intermediary that separates crystals from the liquid phase before the liquid enters the heat exchanger. This separation allows the liquid residence time in the heat exchanger to be optimized for dissolving nuclei without affecting crystal residence time in the evaporator, providing independent adjustment capability.
3Manufacturing precision
If classification zones are installed in the evaporator to separate crystals from solution, then crystal size can be regulated, but the heavier-boiling liquid component cannot be withdrawn separately for further treatment
Solution Approach 1:
The patent extracts the classification function from the evaporator by installing a decanter in the circulation line. The decanter separates crystals from the solution, allowing the heavier-boiling liquid component to be withdrawn separately from the evaporator for further treatment. This extraction of the classification function enables both crystal size regulation and separate liquid phase withdrawal without interfering with each other.
Solution Approach 2:
The decanter acts as an intermediary separation device that divides the crystal-solution mixture into two streams: crystals are removed from circulation while the solution continues through the heat exchanger and back to the evaporator. This intermediary separation enables independent withdrawal of the liquid phase for further treatment while maintaining crystal size regulation.
4Duration of action of moving object
If the interface area for mass transfer decreases as crystals grow, then supersaturation increases to primary nucleation range, but this causes sudden crystal nucleus formation and crystal size fluctuations
Solution Approach 1:
The patent implements a feedback mechanism where crystal nuclei that form in the evaporator are continuously removed by the decanter and destroyed by heating in the heat exchanger. This feedback loop prevents the accumulation of crystal nuclei and maintains stable supersaturation levels, avoiding sudden primary nucleation events and ensuring consistent crystal size throughout the process.
Solution Approach 2:
The patent converts the harmful effect of crystal nuclei formation into a benefit by systematically removing and destroying these nuclei in the decanter and heat exchanger. The nuclei that would otherwise cause unwanted secondary crystallization are instead used as an opportunity to control the crystal population, ensuring that only desired crystal growth occurs in the evaporator.
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 process allows for controlled crystal size regulation without classification zones or nucleation destruction, achieving consistent nucleation and growth rates, and separates the heavier-boiling liquid for further treatment, improving process efficiency and reducing equipment costs.
Implementation Method 1
the lower-boiling liquid components are evaporated off in a forced circulation evaporator and the salt is crystallized out
Implementation Method 2
with the crystals retained suspension being separated and sent for further treatment
Implementation Method 3
treated by heating or diluting to dissolve the crystal nuclei
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a method for continuously treating a solution containing salt, running into a forced flow evaporator, in which the lower boiling liquid compounds are evaporated, the salt is separated by crystallisation whilst controlling the size of the crystals and evacuated, and the treated solution is separated from the circulating suspension by means of a separator which is installed into the circulation line, the crystals are restrained and the solution is then guided for further treatment.