Thank you for the detailed response! I love hearing about other people’s systems, workflow and preferences.
My system uses/requires nitrogen. When I vac out nitrogen (Using venturi pump, with vent line running outside of workspace) I don’t look at it like I am stopping the process. I look at it like it is simply a part of my process.
What are your recovery rates looking like with an active propane system?
How large is your system? Have any more pics you could share?
I find the recovery rate is highly variable depending on the liquid levels and vapor pressures in the collection/solvent tanks, the heat on the collection pot and the amount of cooling in the post pump heat exchanger.
I don’t really think about recovery rate as the defining factor to a system like a lot of people do. I look at material throughput and ease of use/simplicity.
I would take a slower peak recovery rate to have a higher total material throughput and/or a simpler system any day of the week.
For example, right now I really like keeping the recovery/feed tank in my system at around 80psi during operation. This allows for a good flow rate when flooding columns and enough pressure to push through CRC.
I can maintain this pressure easily with an active pure propane system. This is in part because of the heat of compression from recovery pump and in part because of the higher volatility of propane over butane.
Propane will have 80 psi vapor pressure at a temp of about 50F or 10C. This isn’t too crazy of a temperature to keep your solvent tank at while operating and is very easy to achieve by throttling the post-pump heat exchanger and letting the heat of compression naturally raise the temp/pressure in the tank. Also, given a starting temp of 50F, it’s still very easy to cool the liquid down to the -30 to -40C range using a coil in dry ice slurry on the injection side.
Butane on the other hand would need to keep the solvent tank at about 118F or 48C in order to maintain 80psi. This presents some issues and would be much more difficult to work with and maintain.
Running this way pretty much makes a passive recovery setup impossible because by definition you are keeping a higher pressure in the recovery tank than in the collection pot to facilitate injection. This means you will need the compressor in order to work against the pressure gradient on the recovery side.
Also, given the low vapor temperatures coming off a typical collection pot due to subzero extraction temps, the heat of compression afforded by the recovery pump is actually an advantage in gaining back valuable head pressure on the solvent tank to keep the process moving and to avoid having to use nitrogen and its associated headaches and additional steps to deal with.
I have worked out a nice system where I know how to throttle my post-pump heat exchanger by adding different scoop sizes of dry ice at different times so that I have 80-100psi in the solvent tank when I need to inject and about 40-80 psi or slightly lower while I’m just straight recovering and going for fastest recovery rate.
Do you see how operating this way might not give the absolute best peak recovery rate because not long after I want peak recovery rate I want high solvent tank pressure?
That’s why I strike a balance and leave some pressure in the tank even when I’m in “peak recovery mode” instead of just loading my heat exchanger with dry ice and dropping the pressure close to zero.
Do you also see how operating this way along with using pure propane vapor to clear the columns allows me to just focus on racking up column after column?
There’s no nitrogen. There’s no venting. All that’s really needed is to monitor the heat exchangers and pressures and rack up column after column.
But beyond that another big advantage to an active system is there is no need to keep the entire mass of solvent in the solvent tank at or close to zero like in a passive system.
Keeping all the solvent chilled becomes exponentially more difficult and expensive as you step up system size and is much more difficult with propane over butane. Granted, large compressors aren’t cheap but I think they’re generally cheaper and lower maintenance/higher reliability than a large capacity chiller system like what you would need to run a large passive propane system.
Exactly
I am.very fond of passive recovery
And god knows i have one of the largest chillers on can get
I have 7 ton cooling power at -55C
42kw chiller but i recover the same amount /speed as the Corken 491
At 15 kw only advantage it has over the Corken is solvent is cold and ready for use
What was your overall material:oil yield with this blend? How much starting material?
iLL Nye,
Gang Gang
sorry wish i remembered that was one of my first diamond runs in 2017, what i do remember is the material wasnt very good but i almost hit 4% total yield. probably 10 pounds went into it.
@Tech1145 I agree with you 100%. Propane is the way to go . Yes, you have to do some different, tricky things for a certain type of products (ie shatter, etc) Also, the pressures are much higher than running n-butane. You have to stay on that or it can get away from you real quick. Overall tho, it’s much easier and WAY faster to work with. It also consistently comes out much much lighter than bho…
It’s really minuscule, trust me, I “boil” it off everyday. ALL propane you guys see has about ten percent butane.
Those still are not propane pressure rated. 350psi minimum.
My system is rated to 350psi and I just made the switch to full propane. I love it. The product comes out so much better looking. I have noticed a taste difference, but not a smell difference. It does taste a lot more like the natural plant, which can be a good selling point to disp.
The highest I have seen the pressure in my system was about 120psi, and there was quite a bit of solvent in there.
I haven’t tried shatter yet but have heard it makes it difficult, shatter in my market is busted anyway, so not making it isn’t that big of a deal.
Exactly.
Its not the amount of solvent that sets the highest pressure you see, it’s the temperature.
Which is means you can figure out the solvent blend in your tank with a pressure gauge and a thermometer.
And quiet
Another big advantage to propane that I’ve been thinking about lately is a more favorable temp/pressure curve for dealing with heat sensitive compounds while also getting decent pressure and recovery rate in the collection pot.
For example, butane at 23psig in the collection pot will be boiling at a temp of 80F(27C). That’s already pretty warm by our standards and we usually don’t like to subject our heat sensitive compounds to any temps higher than that for a prolonged period.
If you were running an active system and wanted to get faster recovery one of the easiest ways is to increase vapor generation by increasing the pot temp during opportune moments.
If you increase pressure to 30psig the butane is now boiling at 90F(32C). That’s pretty hot and you might not want to have your oil at that temp for too long.
Now look at propane. At about 30psig it is boiling at a nice cool 10F(-12C). At 50psig it’s at 30F(-1C). Both temps are more than acceptable for us.
This will also give you more of a safety margin for turning the heat up on your collection pot.
Let’s say for example that you turn the heat up to 150-160F when the solution is highly diluted with propane and your pressure increases up to 50 psig. The solution is now boiling at 30F(-1C) but the heat exchanger is at 150F.
Any heat sensitive molecule that happens to come in contact with the heat exchanger will rise in temp from 30F(-1C) to whatever it does in the fraction of a second it contacts the exchanger, probably nowhere close to 150F(66C), then quickly ricochet back into the 10F solution and cool back down.
You really can’t increase butane past 30 psig or the temps start to get pretty high for the thermally sensitive molecules. This can potentially limit your recovery rate with butane.
Propane for the win IMO.
i have always wondered this and have been wanting someone with a little better understanding to lay it out for me. My understanding is that with water when you are boiling it, it won’t go over 100C while its boiling no matter how much extra heat you put on it, it will boil and make steam faster but the actual liquid temp shouldn’t go much above 100c.
When we have a liquid butane solution won’t the temp stay at butanes boiling point until most of the solvent is gone? I did a bunch of trial runs of running 20c vs 50c on my collection column and had no difference except increased recovery time as long as I removed the heat when it started getting towards the end.
Plus when you have pressure you are increasing the boiling point of all the compounds in the solution which also helps preserve the terps at higher temps. I have never understood recovering at room temp when you have 20lbs of solvent to recover because the temp of the solution shouldn’t get over 40F but I was never 100% sure. @Photon_noir you are really good at putting things in a way i can understand is this correct or no?
Believe it or not, you answered your own question.
Increased Pressure = Increased Boiling Point
So when your collection vessel is pressurized, the temperature of the escaping vapor is higher than its boiling point at atmospheric pressure. The same is true of water.
The thermodynamic term for this phenomenon is referred to as super heat. Check it out
I put my shatter or batch in a Pyrex dish or casserole dish, an set it in a a larger metal container. Then just add boiling water to your outside container and butane or propane will gass off much better. And best part is no flame to blow yourself up!
Came across this information today and thought it was very useful. Cany copy links but visit Gas Innovations Extraction Solvents Page.
Don’t see anything there related to “propane vs butane extraction”.
Just a supplier stating why their gas is better and AirGas.
What exactly did you run across and why do you think it has relevance here?
But their gas is better than airgas
You got tricked 