How to avoid boiling/bubbling effect under vacuum?

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Discussion Overview

The discussion revolves around the challenge of separating a product mixed with water under low temperature conditions (5-10 deg C) while avoiding boiling and bubbling effects during evaporation under vacuum. Participants explore various methods and considerations related to this process, including vacuum control, surface modifications, and physical barriers.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that better control of the vacuum could help achieve evaporation without creating a hard vacuum, which may lead to rapid evaporation and splashing.
  • Another proposes the idea of floating a sterile, porous item on top of the liquid to mitigate splashing, such as using thin Styrofoam with holes.
  • A different viewpoint emphasizes limiting the undesirable effects of splash rather than preventing it entirely, suggesting this might simplify the problem-solving process.
  • Concerns are raised about the nature of the product and the formation of bubbles, with a suggestion to consider adding a surface modifier or defoamer to reduce bubble formation.
  • Mechanical or ultrasonic vibrations are mentioned as potential methods to help bubbles escape before they grow large enough to cause splashing.

Areas of Agreement / Disagreement

Participants express a range of ideas and approaches, with no clear consensus on the best method to avoid the boiling/bubbling effect. Multiple competing views and suggestions remain in the discussion.

Contextual Notes

Limitations include the specific temperature range and the nature of the product, which are not fully defined. The effectiveness of proposed solutions, such as the use of defoamers or mechanical vibrations, remains uncertain.

Dr SAYEED
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I have a process problem where my product is mixed with water and needs to be separated under low temperature range 5-10 deg C. I hope evaporation under vacuum is the only solution but the boiling effect is creating splash and want to avoid it. Prefreezing or lyophilization is not an option given the temperature range. If some body in the forum can help would be great.
 
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Sounds like you need better control of your "vacuum" so that it is more like "low pressure". After all, you don't need to go to a hard vacuum to get evaporation but a hard vacuum would be more likely to cause rapid evaporation, thus "splash".
 
phinds said:
Sounds like you need better control of your "vacuum" so that it is more like "low pressure". After all, you don't need to go to a hard vacuum to get evaporation but a hard vacuum would be more likely to cause rapid evaporation, thus "splash".
Appreciate your reply also the concern is time and volume, for us 1 litre should evaporate with in 2-3 minutes or so then we transfer to sterile storage. Its a new challenge we came across and I am working on it.

rgds
Sayeed
 
how about floating a sterile, porous item on top of the liquid to quell the spalsh? Something like thin Styrofoam with lots of holes in it.
 
phinds said:
how about floating a sterile, porous item on top of the liquid to quell the spalsh? Something like thin Styrofoam with lots of holes in it.
Thanks for the idea, will give it a try :)
 
I am with phinds second post. Limiting the effects of the splash (or the undesirable effects of it) rather than preventing it happening in the first place probably gives you an easier set of problems to solve.
 
The surface tension of the bubble as it forms must be building up energy prior to bursting and release. We do not know the form of the product or why the bubbles accumulate until they burst and splash.

What is it about the product that allows bubbles to form. Could some surface modifier like a drop of oil or a de-foamer be added to prevent the bubbles forming. https://en.wikipedia.org/wiki/Defoamer

Maybe a mechanical or ultrasonic vibration would help the bubbles escape from the material before they can accumulate to a size that becomes a problem.
 

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