So I have been running distillation and doing pretty well(thanks to a ton of help from you guys!!!) but I am running into the same problem every time and have yet to find a fix or reason for the problem.
When I run winterized crude on a first pass, I am having trouble with my pressure going low enough, and its sitting around 2000 microns at the beginning of the run and as it goes on it drops to around 1000-1200 microns. This is low enough for me to push a first pass through but is causing oxidation and increasing the length of the run. However when I run the 2nd pass, I am getting my pressure down to 300ish microns at the start and going down to 100-150 microns as the run goes on. I am getting around 50-100 microns blanked off(My vacuum pump is not the greatest, but is all I have to work with until the company has funds to upgrade).
While this has been getting me some decent distillate on the 2nd pass(85-94% so far) its still leaving more to be desired and I am not sure what the cause of this is. Any tips or information would be greatly appreciated.
I have a Welch 1400 DuoSeal pump and an Ai T1 2L glass vacuum cold trap(not a fan of Across’s glass but again all I have until we have the extra funds to upgrade the setup)
@Siosis Its not decarbed fully. The crude we had tested in the past was only about 50% decarbed and we haven’t changed the decarb length since the distillate has been testing 100% D-9 THC and no THCA.
I’m curious the science behind why this is causing the issue and anything I could do to fix it without a vacuum oven?
Edit: The distillate isnt 100% D-9 just the THC present in it is lol figured this is a given but wanted to note anyways.
More gassed put off the less it’s decarbed. Your pump can’t keep up with the amount of gasses that are put off as you decarb it in your mantle. Therefore the pressure rises in the system
You need more pump. If you can, add a 7 to 8 cfm dual stage pump for a 2L system. Use them both but use the welch as a roughing pump (decarb, volatiles, and heads ) valve in your higher cfm pump as you get to mains. This keeps your second pump cleaner as volatiles that by pass the trap will end up in the roughing pump.
I have a larger setup pieced together for them to purchase with a better pump but due to it being a startup, its not as immediate a need as some other things in the lab. Ill definitely recommend them buying two so we have one for the decarb and volatiles on the larger setup!
Any recommendations on decarbing the crude safely without oxidizing too much of it before putting it in the boiling flask without a vacuum oven?
There are reactors for decarb purposes, I have never used one. If you size pumps go for around 4cfm per liter of boiling flask. Not saying it won’t work with less.
I agree on the need to fully decarb crude before distillation. As you proceed through your first pass you are releasing both CO2 and volatiles that should have come off durring the decarb step. This is at least part of your vac issue.
A blanked off Welch 1400 should pull much lower than 50-100u. How many times do you flush out the oil in between runs? You should change vac oil as follows:
Warm up the pump for 30 minutes
Drop the oil
Refill about half way with clean oil
Warm up the pump for 30 minutes
Drop the oil
Repeat this until the oil comes out clear with without any smell. Then fill it up to near the fill line. If after this process you aren’t pulling down to below 10u blanked off then there is a problem.
You should also ensure you are using a quality vac oil. The viscosity of the vac oil is critical to vacuum depth. I use vac oil from Cacejen vacuum, personally. It’s the best one I’ve used.
What are you using for a vac gauge? When was the last time you had a NIST calibration done? Distillations are a fairly dirty environment for a vacuum thermocouple. I find that if I don’t calibrate every 6 to 10 months the readings become very inaccurate. The errors are not equal at different depths either-- they get further off as the pressure goes up. When I got mine back the last time at a 5u standard it was reading 20u but at a 500u standard it was reading 1800u. If you’re out of calibration on the gauge your actual depth may not be as bad as you think.