De-foaming Solution for Food-Grade Reactors/Vats and Packaging Lines:
Cavitus Ultrasonic Defoaming System (UDS)

The Problems Solved

Foam is a dispersion of gas in liquid, with a density approaching that of the gas, i.e., in which the distances between the individual bubbles are very small. However, its mechanical behaviour can be similar to that of a solid, depending on the type of foam.

In food and beverage manufacturing, foam has historically been controlled by the use of mechanical breakers, lowering packaging container temperatures below the ambient environment, or by the addition of chemical anti-foams. Nevertheless, problems remain, for example:

• Limitations on throughput
• Product losses and wastage
• Microbial contamination of product packaging
• Production delays, including occasional shutdowns
• Obstruction of ducts and exhaust valves
• Wetting of outlet air filters
• Malfunction of control instruments

The Technology

High power ultrasonics (or 'HPU') can be used to disperse foam through a combination of fluctuating high pressures, bubble resonance, cavitation, radiation pressure and sonic wind. When an ultrasonic standing wave is set up in air, a series of nodes and anti-nodes are formed. No use of de-foaming chemicals, temperature reduction or mechanical breakers is required.

Solution and Benefits

Cavitus is the exclusive distributor of this proprietary technology, the Ultrasonic De-foaming System (or 'UDS'), by which one or more stepped-plate, high-energy, piezoelectric transducers are used to direct air-borne ultrasound at 20-40 kHz to the liquid surface upon which the foam is being generated from above. The proprietary solution has been developed by the Power Ultrasonic Group of the Institute of Acoustics (CSIC), Spain, and is registered under US patent 5299175.

Advantages of the UDS - offering typical customers a 2-year ROI - include:

Improved bottle/package fill level and reduced product loss/waste; Enhanced bottling/packaging production capacity and throughput; Simplified and reduced maintenance, e.g., no moving parts and readily sterilisable Lower container/packaging reject rates; No airflow to interfere with plant environment; Easily installed into existing manufacturing lines and no physical interaction with the production process; Reduced anti-foam chemical usage; Improved food safety from reduced microbiological hazard, e.g., cap mould; and Reduced heating/cooling-related energy costs as a foam intervention strategy.

Applications

On canning lines, the air-borne ultrasonic radiation is focused on the working area where the foam excess is quickly destroyed to avoid liquid losses. In typical operations, 2000 containers/minute can be processed, using two focused transducers in parallel to cover the top container surface area with high-intensity sound pressure levels (165 dB). Relatively low power is required -- approximately 150-300W.



In fermentation reactors, the air-borne ultrasonic radiation is focused on a small working area, which results in the foam being destroyed, causing the foam around it to 'cave in' to the hole created the foam excess that has already been eliminated. Customers have seen the rate of foam breaking at 200 litres/minute, using input power on the transducer of 300W, with energy consumption of 30 Wh/m3, in a 6 mtr. diameter reactor.

Technical Specifications

• Air borne ultrasonic generator
• Diameter of the radiator 200-1000mm
• Power capacity 0.3-1kW
• Maximum intensity level 175dB
• Electro acoustic efficiency 75-80%
• Electronic dynamic control of resonance
• Titanium alloy plate radiator
• Stepped plate focused transducer
• Voltage controlled oscillator
• Frequency range 20-40kHz