4.1. Equipment
Supercritical CO2 fluid extraction takes place inside a reactor
under high pressure conditions (pressure above 72 bar). This fact
makes it difficult to introduce a mechanical agitation system in
the reactor, as well as an ultrasonic transducer, which represents
the main obstacle to the application of ultrasound in this kind of
process. To address it, two different set-ups may be mentioned.
One of them consists of the use of a commercial sound probe
joined to the wall of the extractor. As the transducer is fitted externally,
it is expected that there will be a power attenuation as the
ultrasound passes through the stainless steel vessel walls
(Balachandran et al., 2006).