Crystallization Apparatus with Adjustable Baffle for Crystal Size Control
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Solution Overview
Problem
Existing crystallization methods, such as those using draft tube baffled agitated vessels, fail to produce uniformly sized crystals due to poorly defined and controlled hydrodynamic regimes, resulting in small and poorly defined product crystals.
Innovation Solution
A multi-function chemical reactor with a three-phase crystallization unit incorporating a coaxial draft tube, agitator, and adjustable coaxial vertical baffle, allowing for simultaneous reaction, solvent extraction, crystallization, and direct heat transfer, enabling controlled hydrodynamic conditions for producing large, well-defined crystals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional draft tube baffled agitated vessels are used for crystallization, then the system can perform reaction and crystallization, but the hydrodynamic regime is poorly defined and controlled resulting in small and badly defined crystals
Solution Approach 1:
The apparatus is divided into three distinct sections: upper section for solvent extraction, intermediate section for phase separation, and lower section for crystallization. Each section is optimized for its specific function, allowing independent control of hydrodynamic conditions in the crystallization zone while maintaining overall process integration.
Solution Approach 2:
The intermediate section with coaxial vertical baffles acts as a mediator between the upper solvent extraction section and the lower crystallization section. It facilitates controlled phase separation and provides a transition zone that establishes well-defined hydrodynamic conditions for crystal growth.
2Productivity
If multiple agitated vessels in series are used for reaction and crystallization, then the process can be carried out, but the hydrodynamic regime remains poorly defined and crystals are small and badly defined
Solution Approach 1:
The apparatus merges solvent extraction, phase separation, and crystallization functions into a single integrated unit with three sections. This eliminates the need for multiple separate agitated vessels while maintaining process productivity, and provides controlled hydrodynamic conditions that produce high-quality crystals.
Solution Approach 2:
The crystallizer apparatus performs multiple functions simultaneously: reaction, solvent extraction, phase separation, and crystallization. The coaxial draft tube configuration enables this multi-functionality by providing structured flow patterns that benefit all process stages while optimizing crystal growth conditions.
3Ease of operation
If classical hydrodynamic conditions are not maintained, then the process can operate, but crystal size distribution becomes poor and crystals are poorly defined
Solution Approach 1:
The apparatus employs adjustable coaxial vertical baffles that can be moved to optimize the gap between the draft tube and baffle. This dynamic adjustment capability allows the system to maintain classical hydrodynamic conditions for crystal growth while adapting to different operating conditions, ensuring consistent crystal size distribution.
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 apparatus achieves the production of crystals with a consistent size range of 350 to 550 microns by maintaining classical hydrodynamic conditions and optimizing mass transfer and phase separation, significantly improving crystal quality compared to conventional methods.
Implementation Method 1
The hydrodynamic regime at these agitated vessels are poorly defined and controlled far from the classical hydrodynamic conditions required for appropriate crystallization
Implementation Method 2
producing a three-phase stream that is fed to a decanter for separation of the loaded solvent; the mother liquor; and the product
Implementation Method 3
Methods and apparatus for crystallization of salts from solution are well known in the chemical process industry
Implementation Method 4
A method for crystallization according to which cooling of a saturated solution is carried out directly by employing a volatile liquid was described
Implementation Method 5
the production of potassium nitrate from KCl and Nitric acid, by solvent extraction has been applied at several production plants
Data Source
AI summary
A reaction-crystallization apparatus for carrying out reaction and/or solvent extraction and/or crystallization of soluble salts has an upper section having a top and a decanter. The decanter has a vertical vessel having a horizontal weir at the top of the upper section. The top of the upper section has an outlet for removing a light phase at the top of the decanter. The apparatus has a lower section, including a crystallizer. The crystallizer includes: a coaxial draft tube; a feed pipe; an agitator inside the draft tube; and at least one outlet at the bottom for crystal slurry removal. The apparatus has an intermediate section sandwiched between the lower section and the upper section such that the sections are in fluid communication and includes at least one coaxial vertical baffle with a gap between the draft tube and the coaxial vertical baffle and is adjustable by moving the baffle.