Gas Injection Right into the Cavitation Zone

Multiphase Cavitation

08.05.2015 The Multi Phase Cavitator Insert (InsertMPC48) from Hielscher is designed to improve the ultrasonic processing of liquid/liquid or liquid/gas mixes. 48 very fine cannulas inject liquid or gas into a liquid phase right in the cavitation zone. This creates very small suspended droplets or gas bubbles yielding a very high specific surface area.

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Multiphase Cavitation

On using the insert with an ultrasonic reactor, cavitation produces high hydraulic shear and breaks the injected phase into sub-micron and nanosize droplets (Picture: Hielscher Ultrasonics)

This insert is particularly useful for emulsion chemistry, for example in phase-transfer reactions, phase-transfer catalysis (PTC) or liquid-liquid extraction. Another interesting field of application is the precipitation of particles from two liquid precursors or sono-crystallization. This insert is designed for the manufacturer´s flow cell reactors and allows batch or continuous processing.

Ultrasonication is an effective procedure for emulsification and mixing. Unlike the conventional setup, where separate phases are combined before they enter the flow cell and the cavitation, this flow cell insert improves the combination of the two phases. When a liquid is injected through the 48 fine cannulas, it enters the flow cell in very narrow strands. The insert uses very 48 fine medical cannulas with inner diameters from 0.3 to 1.2 mm. These cannulas can be easily replaced and are a low cost consumable (sterile, approx. 2 ct/pc). The ultrasonic cavitation (at 20 kHz) cuts the 48 incoming liquid strands into small droplets when they enter the liquid phase in the flow cell. The design applies the same feed pressure from one supply to all 48 cannulas to level the flow between the cannulas.

Ultrasonic reactors are often used to emulsify, to improve phase-transfer process kinetics or dissolving rates in liquid-liquid phase systems. Examples of such processes are the oxidative desulfurization with hydrogen peroxide and subsequent solvent extraction or the base-catalyzed transesterification of triglycerides. Limited solubility of one reagent phase in another reagent phase is a significant problem in the process emulsion chemistry as both phases react with each other only at the interface. Without ultrasonics, this results in low reaction rates and a slow conversion kinetics in two-phase systems. On using the insert with an ultrasonic reactor, cavitation produces high hydraulic shear and breaks the injected phase into sub-micron and nanosize droplets. As the specific surface area of the phase boundary is influential for the chemical rate of reaction, this significant reduction in droplet diameter improves the reaction kinetics and may reduce or eliminate the need for phase-transfer agents. The volume percentage of the injected phase may be lowered, because finer emulsions need less volume to provide the same contact surface with the other reagent phase.

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Hall 6.0 – A50

Facts for Decision-Makers:

 

  • effective emulsion process
  • ultrasonic cavitation
  • high hydraulic shear

 

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