Multistage Membrane Crystallization for Uniform Crystal Size
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current crystallization processes face limitations in controlling supersaturated degrees, leading to low micromixing efficiency, uneven local supersaturation, and uncontrollable burst nucleation due to insufficient temperature and concentration control, which restricts the production of crystal products with uniform size and high purity.
Innovation Solution
A continuous crystallization method utilizing a multistage membrane system, where membrane surfaces act as nucleation interfaces and antisolvent dispersion interfaces, allowing for precise control of temperature, concentration, and mass transfer across membrane modules to regulate crystal nucleation and growth, eliminating the need for seed crystals and improving mixing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If single temperature control or concentration control is used in crystallization, then the control interface is small and insufficient, but this leads to low micromixing efficiency, uneven local supersaturated degree and uncontrollable burst nucleation
Solution Approach 1:
The crystallization process is segmented into multiple independent stages (nucleation stage, growth stage, and optimization stage), each controlled by a separate membrane module with specific temperature and concentration parameters. This segmentation allows precise control of supersaturation at each stage, preventing burst nucleation while maintaining manageable control complexity through modular design.
Solution Approach 2:
The system dynamically changes temperature and concentration parameters across different membrane modules to create controlled supersaturation gradients. By adjusting these parameters independently in each module, the system achieves precise control over crystal nucleation and growth without requiring a complex single-interface control system.
2Quantity of substance
If antisolvent is added dropwise with stirring, then the diffusion rate is limited and supersaturation level at addition point is much higher, but this causes burst nucleation and wide crystal size distribution
Solution Approach 1:
The membrane module serves as an intermediary device that controls antisolvent addition through its selective permeability. Instead of direct dropwise addition causing localized supersaturation, the membrane gradually allows antisolvent to permeate into the crystallization solution, creating a uniform supersaturation distribution that prevents burst nucleation and produces narrow crystal size distribution.
3Ease of operation
If jet way is used for antisolvent addition, then mixing is improved, but high turbulence intensity results in more crystal nucleation and low growth rate
Solution Approach 1:
The membrane module creates local quality differences in the crystallization system by allowing controlled antisolvent permeation at specific locations. This localized control achieves sufficient mixing for uniform supersaturation without generating system-wide turbulence, thereby maintaining high crystal growth rates while avoiding excessive nucleation.
4Manufacturing precision
If seed crystals are added based on experience, then crystal growth can be controlled, but there is no theoretical basis for quantity, size and temperature of addition
Solution Approach 1:
The multistage membrane system provides inherent feedback control by monitoring temperature, concentration, and supersaturation levels at each stage. This feedback mechanism replaces empirical seed crystal addition with a controlled process where the membrane modules automatically adjust antisolvent permeation and temperature to maintain optimal crystallization conditions, making the process scalable and adaptable to different production requirements.
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 enables precise control over crystal size distribution and morphology, avoiding burst nucleation and agglomeration, resulting in crystal products with uniform sizes and improved quality, expanding the application range of cooling and antisolvent crystallization technologies.
Implementation Method 1
a membrane module combination (19) comprising a multistage membrane; the crystallization solution and auxiliary control solution flow on both sides of the membrane, respectively
Implementation Method 2
Because of the temperature difference between cooling liquid and crystallization solution, the crystallization solution reaches a supersaturated degree on the surface of the membrane to nucleate
Implementation Method 3
cooling crystallization is a typical crystallization technology that produces the supersaturated degree by reducing solution temperature
Implementation Method 4
In the antisolvent crystallization process, crystallization solution and antisolvent flow on the both sides of the membrane. The antisolvent permeates into the crystallization solution side across the membrane
Data Source
AI summary
The present invention provides a continuous crystallization method under control of the multistage membrane modules, and belongs to the technical field of crystallization engineering. A crystallization solution is added to a crystallizer, and a stirring apparatus and a temperature control apparatus are started. After the system running stability, the loop of crystallization is started. Meanwhile, the coolant or antisolvent feed liquid loop is also started. The crystallization solution can respectively conduct crystal nucleation, growth and ripening in the multistage membrane modules, and then the crystallization solution is transported into a filter device and a drying apparatus to obtain the final crystal products. The desired crystal products can be obtained by the systematical control of the nucleation and crystal growth through the flow and the temperature of the crystallization solution, coolant or antisolvent feed liquid, and the contact time between two liquid phases.