Crystallization Device Metastable Region Control
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Solution Overview
Problem
Current crystallization methods for obtaining sugar crystals face challenges in achieving rapid crystallization with minimal formation of unwanted crystal nuclei, especially in solutions of low purity, as they require precise control of supersaturation boundaries which are difficult to maintain due to variable physical and chemical properties.
Innovation Solution
A closed-loop process control method that determines the metastable region above the saturation curve using sensors to prevent new crystal nuclei formation while allowing existing crystals to grow rapidly, eliminating the need for complex mathematical models and empirical specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If open-loop process control with empirical specifications is used to prevent crystal nuclei formation, then crystal size uniformity is improved, but the process cannot adapt to variable physical and chemical properties of the mother solution
Solution Approach 1:
The patent implements closed-loop process control by continuously measuring the actual position of the saturation curve and the metastable region boundary using optical sensors, and adjusting process parameters accordingly. This feedback mechanism allows the system to adapt to variable mother solution properties while maintaining precise control over crystal growth conditions, resolving the contradiction between manufacturing precision and adaptability.
Solution Approach 2:
The patent dynamically adjusts process parameters (temperature, concentration) based on real-time detection of the metastable region boundary. By changing operating parameters according to actual solution conditions rather than fixed empirical specifications, the system maintains crystal size uniformity while adapting to variable solution properties.
2Productivity
If supersaturation is increased to accelerate crystal growth, then productivity is improved, but formation of primary and secondary crystal nuclei increases
Solution Approach 1:
The patent dynamically determines the boundary of the metastable region during the crystallization process using optical measurements, rather than relying on fixed empirical specifications. This dynamic approach allows the system to operate at optimal supersaturation levels that maximize crystal growth rate while preventing nucleation, as the control limits are continuously adapted to actual solution conditions.
Solution Approach 2:
The patent replaces empirical mechanical control methods with optical measurement and closed-loop control. By using light scattering and absorption measurements to detect the metastable region boundary, the system can precisely control supersaturation levels to promote crystal growth while preventing nucleation, substituting trial-and-error empirical approaches with precise optical-based feedback control.
3Manufacturing precision
If precise control of supersaturation boundaries is maintained to prevent nucleation, then crystal quality is improved, but device complexity increases due to sophisticated control systems
Solution Approach 1:
The patent replaces complex mechanical control systems with optical measurement techniques. By using light scattering and absorption measurements to detect the metastable region boundary, the system achieves precise control of supersaturation with simpler instrumentation, reducing device complexity while maintaining high crystal quality.
Solution Approach 2:
The system uses the mother solution itself as the measurement medium - the solution's optical properties (light scattering, absorption) directly indicate its supersaturation state and metastable region boundary. This self-service approach eliminates the need for external complex analytical instruments, achieving precise control with minimal additional device complexity.
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 faster crystal growth with reduced formation of fines, improving crystal quality and process efficiency by maintaining operation within a metastable region, allowing for online monitoring and adaptation to variable system conditions.
Implementation Method 1
data are currently determined by sensors in the mother solution
Implementation Method 2
supersaturation of the mother solution is brought about by open and/or closed-loop control of the temperature
Implementation Method 3
the seed crystals are grown as crystal nuclei by continuous closed-loop process control
Data Source
AI summary
A method for obtaining crystals from a mother solution operates such that mother solution is fed into a crystallisation device. Supersaturation of the mother solution is brought about by open and/or closed-loop control of the temperature (□). Seed crystals are added to the mother solution at a seeding point (Sp). The seed crystals are grown as nuclei by continuous closed-loop process control and are finally removed from the method as crystals. They form the product yield. The formation of crystal nuclei in the mother solution is countered by steps in the closed-loop process control. During the closed-loop process control and the crystallisation procedure, the position of the limit (M) of the formation of secondary nuclei is determined using sensors that detect data currently, wherein the position of the limit (M) is established as a value of the concentration (c) and the temperature (□) from these data. This determined position of the limit (M) of the formation of crystal nuclei is used as the basis for the closed-loop process control of the crystallisation.