Have a bit of an issue with a used rotovap I just picked up.
I have a temp probe inside boiling flask and another probe in water bath.
First I heat the water bath to 50c (double checked with second temp probe)
This gives my ethanol in the flask a temp of 47c
When I turn my vacuum pump on, as soon as distillation begins ~(28inhg) and the condenser is dripping the temp in the boiling flask begins to drop, as soon as the temp drops to ~32-33c distillation stops.
After distillation stops I bleed air back into the system and the temp rises.
If it wasn’t acting like an insulator before, why would it when vacuum is pulled?
You don’t show what you are using to control your heating elements (assuming its a PID of some sort), but if you have access to a temp probe that is inside your evaporation flask why not use that signal to drive your heating element instead of the temp of the liquid inside your drum? Especially without the fluid movement afforded by a rotating evaporation flask moving your thermal fluid around in a rotovap, the drum temp probe is going to lag significantly behind the temperature of whats inside your evaporation keg.
I found the issue, my heating element was wired incorrectly.
The PID is controlled by the probe inside the boiling flask, also there is an agitator inside the boiling flask and a circulating pump in the water bath.
The water bath runs ~20c hotter than the boiling flask under full vac.
Right now I am maintaining
BF 38c
WB 62c
Vacuum 600mmhg
I loaded 5 gallons in the still, I’m curious to see the recovery rates.
I don’t know the exact recovery time, ran 15 gallons through it in about 3-4 hours. All of it comes out 190+ proof. I will wash more biomass Monday and record some accurate data then.
I think once it’s dialed it should compete/surpass a 50l Roto.
are you making a thin film on the evaporation surface? that gets you “thin film evaporator”, of which a rotovap is one flavor.
are you achieving that thin film by rotating anything?
if no to either, then it’s not a rotovap or particularly conceptually related to one (based on already agreed upon terminology)
do you have an agitator in there? (Edit: yep🤔)
Do you understand that you can have your water bath at 90C and your boiling ethanol we still be at whatever boiling point (37C?) you’ve set with your vac pump?
@greenbuggy is correct. you are controlling at the wrong spot
Edit: beat me to it! congrats!! I really should know to read the whole thread before posting by now…