DIY vac distillation system using peltier thermoelectric heat pumps

[The Day Tripper]

I've been playing around with this idea for a few days, and would like some feedback on it. Basically it involves using a 500ml Erlenmeyer flask, a few peltier heat/cool plates, a few diy copper pipe condensers, a 500ml vacuum flask, a water cooling system, and a vac source.

The idea is to use the peltier plates heating and cooling abilities, to both heat the flask in which you have the liquid to be distilled, and attach GPU/CPU water blocks, and a small pump to circulate water to the condensers on the cold side of the plates.

Uses rubber bungs, and copper tubing to connect it all instead of glass, as well as two diy condensers via copper coils in water baths. One to condense the solvent, and another to ensure no vapor gets into your vac source. Set up a water circulation system with a small pump, and cool the condensers via the water blocks on the cold side of the peltier plates.

Since its going to be a vac setup, temps don't really need to be very high, ideally as low as possible while still achieving condensation. Variable power input to the plates, and the pump (slower circulation/less cooling), could control temps using an ir thermometer.

Even if diy copper condensers are not used, and you go all glass, i don't see why using the heating and cooling power of peltier plates could not be taken advantage of here. Could even be applied to a soxhelt setup.

Basically what I'm really asking about is if peltier plates are a viable option to use as heat/cold sources in a distillation setup, whether it be all glass, vacuum, soxhelt, or diy with copper coil condensers.

Any reason why this would not work? Safety concerns about anything?

Obviously it would be tested using water a few times before trying anything flammable/volatile, and safety would be stressed here, but i don't see any flaws that would prevent this from working.

Feedback on this idea would be appreciated

 

[Dr_Sister]

Flat bottomed flasks, with the exception of filtration flasks, will not stand up to high vacuum, they will implode. And filtration flasks are so thick they don't heat evenly and often fracture due to heat stress. This can happen when heating or if they cool to quickly or someone makes the mistake of trying to cool them by immersing them in cold water.

Its unlikely to be a safety hazard unless you are distilling a flammable solvent, but can be incredibly discouraging at the end of a long synthesis. Speaking from painful personal experience, gained the hard way. Distillation rigs can be purchased inexpensively on eBay, btw.

I don't know enough about peltier plates to offer an opinion on that aspect of you plan.

light and blessings
Sistah

 

[InMotion]

As dr. sister said don't use flat bottom flasks under vacuum. Copper condenser will work in some cases so long as acid/base and funky organics aren't being past through. Make sure you're vacuum pump can handle the approximate volume of air in the entire set-up if you are going to be building condensers and such(cubic feet/liter per second I believe is the figure that concerns this).

Also you would like to have an adequate cold trap so you don't wreck your vacuum.This is a cold air-tight(of course) vessel between your collection flask and your vacuum. It is cooled either by salt/water or something more elaborate such as dry-ice/acetone depending on what is being distilled.

A way to get around using a flat surface is to use a proper pot/pan/heat resistent dish filled with water or non-flammable oil. If you can heat this to an adequate temperature you can simply suspend your distillation flask half way into the oil/water and go right ahead! This is called an oil bath or a hot water bath.

Another concern and reason to go all glass as dr. sister has said is you can use a 'pig' or distillation receiver to switch fractions that are collecting without breaking the vacuum. If you are simply ripping/recycling high boiling solvents(xylene, toluene, limonene, acetophenone) this is of no concern.