Dear Rosaria Piseri,

 

Thank you for your inquiry. We have a few possible solutions that can be used for your application. I need to understand a little more about the current ultrasonic set-up before I can make a recommendation.

 

Questions:

1.)     I understand the frequency and power specs of the current ultrasonic machine. Could you give some details about the physical arrangement?

a.       Is this a bath or probe with flow-cell or static chamber?

b.       What are the dimensions of the bath or reactor cell?

2.)     If the current system is a probe what are the specifications?

a.       Total length and length submersed?

b.       Tip diameter?

c.       Do you know the tip amplitude peak to peak?

3.)     Can you send a picture of the current system? Probe and reaction cell?

4.)     Is the current tested treatment flow-through or batch?

a.       What is the treatment time? This will effect the design of the flow-cell and power requirements.

 

We can offer a 40 kHz solution but I don’t know of hand if it will help your application. We would need to provide some consulting time and organize some tests to learn what would be best for your application. The answer is of course very depended on the material. Generally speaking a lower frequency (e.g. 20 kHz) would offer bigger cavitation bubbles and stronger acoustic pressure resulting in strong streaming and mixing. As you may know 40 kHz would provide more cavitation density but smaller bubbles and less acoustic pressure. We really need to learn if extraction of this material is most improved form the cavitation or from the probe pressure and resulting acoustic streaming. Can you make a conclusion from your tests and experience?

 

If the strong acoustic pressure from the probe tip is a critical element we would propose a fixed frequency high powered probe and flow cell as you suggested. I’m guessing that we may have a problem using a 6 mm probe due to power limitations wearing issues. We may need to consider a larger probe to increase the load (larger surface area) and allow more power to be deliver to the liquid. Also a small probe will likely ware out quickly due to cavitation pitting on the tip. This will drive the probe out of resonance and require frequent replacement. A larger probe should offer longer life and higher flow rates.

 

If we find that cavitation is the primary extraction force we can consider our MMM wideband technology in a flow through tube arrangement. Here we would drive at a primary resonance frequency of  20 kHz and use our proprietary modulation techniques to stimulate wideband frequency effects. This technology can stimulate coupled harmonics to generate cavitation across a wide range of frequencies from 20 kHz to 1 MHz. In most sonochemical or extraction environments we are seeing an improved reaction or extraction time with this technology. It is also very easy to adapt to existing industrial processes.

 

Please reply to my questions above and we can begin to discuss options. Also please provide your telephone number so we can discuss the issues.

 

I look forward to your reply.

 

Mario Plasencia

Active Ultrasonics S.ar.l.

Puits-Godet 6A, CH-2000 Neuchatel,  Switzerland

Tel: +41 32 727 3807  Fax: +41 32 727 3809 

Email:  m.plasencia@activeultrasonics.com

Web Pages:  www.activeultrasonics.com

 

-----Original Message-----
From: Tir na nog seaweed [mailto:tirnanogseaweed@eircom.net]
Sent: Sunday, 21 March, 2004 17:41
To: sales@activeultrasonics.com
Subject: ultrasonic extraction

 

Good morning,

 

We are a small company producing seaweed extracts from water and vegetable oil.

 

We have a small extracting ultrasound machine of 2,5 lt of which we are quite happy, but we need now a production of extract of about 800 - 1000 lts a day and the engineer who made for us this machine is not yet available.

 

The details of our machine are 25 kHz, 50 Hz, 230 v, 200 W.

 

Could you send us more information and a quotation of your machines?

 

We think the continuous flow through a probe of 6 mm would be good. What about 40 kHz? Is it too much for us or could it extract more goods from seaweed (which are actually a very hard plant to extract)

 

Thanks for your prompt reply

 

Best regards

 

Rosaria Piseri

Tir na nOg Seaweed LTD

Aran islands

Co. Galway

Ireland