ptfe seals and explosion proof, used in industrial propane/butane facilities, same price as small pneumatic pumps, once I finish playing around with mine and making adjustments I’ll be designing a skid for it with a condensor and chilling method to match.
1 Like
Yeah i’ve been playing with liquid ring vacuum pumps lately. Haven’t used it as a compressor before but for a few grand you can get one that makes a GC5000 look tiny in terms of CFM. I am pretty shocked the state of recovery pumps is still so lame, how come someone hasn’t bought one of these, put a pot leaf on it and sold it for 5x the price? People would have eaten it up too.
8 Likes
Well I can promise I won’t put a leaf on it, or mark it up anywhere in the hundreds of percents. I’ll post up a thread once it comes in and it’s dialed.
3 Likes
For vapor generation you are running into all the problems associated with large sized vessels and the square-cube law.
One solution is a butane FFE. You would need to setup a liquid pump, evaporator, new oil collection scheme, and a new vapor path. You could also try and tune/size the evaporator to handle the incoming volume directly from your extraction setup to eliminate the liquid pump and intermediate holding vessel. IMO, based on how you currently operate, this sounds like a high-disruption solution and would change a lot of things you’re currently used to.
To me it sounds like you essentially have a very large batch extraction system. I think the easiest and simplest way to increase your vapor generation without doing major changes is to increase the efficiency with which you transfer heat into the solution in your current collection vessel.
One option is to setup a liquid pump and continuously send the solution through an exterior heat exchanger, like a tube-in-tube that empties back into the collection pot it started in. If you know the company Bhogart, they have a setup like this that pumps the solution through sprayers into a simple jacketed tube that sits on top of the collection pot and empties right back into it.
This allows a somewhat simple way of increasing the surface area to volume ratio of the collection pot you currently have. Setting up and running a liquid pump for butane makes me nervous and I would not want to deal with it, but this may be the quickest/easiest solution for you.
Another way is to use a very efficient internal heat exchanger inside the collection pot itself. A simple coil or two won’t cut it for a setup like yours.
The petroleum industry uses something called a kettle reboiler to deal with re-heating the bottoms product in large fractional distillation columns. You might need to use something similar as your collection pot.
You can see it’s basically a vessel with a U-tube sheet inserted inside. Using this tube arrangement will give you the max amount of surface area with relatively short tube length in comparison to a standard coil. You probably don’t need the weir or liquid level plate pictured in the diagrams.
This could probably be done relatively simply if you can get your vessels modified (just a port in the side, not too difficult) to accept the U-tube bundle. Otherwise in the grand scheme of your operation, I believe getting new vessels (kettle reboilers) fabbed would be the easiest and least complicated/expensive of the available options. No liquid pumps, and it’s not really changing your current overall operating procedures to a great degree.
9 Likes
Thank you
My curiosity has been triggered by a half ffe so to say
Yust the vapor side
My butane comes from a intermediate tank so biomass tank -media tank - collection pot so i am contemplating
i if i can control this transfer to an large evaporation surface to feed the 24 cfm
Of the compressor
1 Like
Interesting I already I have a tank with the u tube in it
4 Likes
My inquiries into liquid ring compressors have gone well. You can get a unit the same price as the MVP with literally 10x the CFM. Seems like everyone running active has been taken for a ride so far!
1 Like
Exactly
Since the vitamine E tragedy s i have been concentrating on big active recovery options and Basicly the sky is the limit in sizing if focused on oilless piston compressors and will report back
But man O man this is all 30 years proven industrial equipment so don t really expect hick ups
1 Like
Anyone on the west coast running butane who would like to test run one of these?
2 Likes
What s the price tag ?
Garateed no lube to pollute the tane ?
No lube, about 15k for the one I’m looking at now (and I’m looking for other ones). Does use water though. Might need to put your molsieves after the compressor instead of before
1 Like
Every Milk cow farmer uses them
Sihi is a strong brand
1 Like
FInally! Someone on the new wave! We’re building a 96cfm recovery skid using liquid ring compressors.
4 Likes
Which brand? I got my quote from Nash
1 Like
I need 22kw of heat to feed 12cfm
How the hell Are you gooing to feed 196kw of heat to a collection tank
Love to hear your solutions 
You don’t need to increase the heating power necessarily. Just make the heat transfer more efficient. Butane FFEs are a thing now.
2 Likes
I know but I am already transferring this heat to a jacket an internal coil and a
Tube in tube solvent entry to collection pot and it s maxed out and only works if I restrain the solvent amount. Entering the collection pot
But imagine the numbers you can recover at decent pressure 96cfm
Should be in the 40+ pounds a minute
Woah hope it works out
1 Like
The tube in tube doesn’t give you headspace for the vapor, although I’m sure it gets the butane pretty warm. It’s a combination of a lot of factors, you need surface area, you need a good vapor path, enough room for the butane vapors to be generated, and enough movement by the pump to push it, and enough surface area and heat transfer to recondense the butane so there is somewhere to push the vapor to. There is alot info out there about moving butane and thermodynamics. Lots of books for petroleum Chem engineers. I’ll try to find you some of the stuff I’ve been checking out. Definitely not claiming or even hoping to hit 40lbs a minute though. I don’t think the cfm vs recovery rate if you charted it out would be linear even if you accounted for surface area and heating/cooling power.
1 Like
All info is welcome
But quite amazing it s taking us 10+ years to figure this out
The math the equipment all exist for way longer yet I sat watching hvac units
In paralel chuming night and day 
Guess ignorance is bliss sometimes bites you in the butt
2 Likes
@GreenMachine_Consult @MagisterChemist
I’m curious why you have chosen the liquid ring compressor design. To me they seem slightly more complicated and less suited to our application than the vertical/horizontal oilless reciprocating compressor design.
I briefly researched liquid ring compressor designs and came up with the following points of contention, let me know what you guys think because I didn’t really dig in fully:
-
Compressed outlet gas stream will likely contain some of the working fluid (water or oil) which will require a vapor-liquid separator somewhere downstream of the pump’s discharge.
-
Will typically require a system to clean/cool/recirculate the working “ring” fluid.
-
Typically uses unlubricated roller type bearings that don’t have the same long term reliability as hydrodynamic bearings like those found in oilless reciprocating compressors.
-
I’m not sure about this one but it seems liquid ring compressors are typically designed for a specific compression ratio and can run into over or under compression situations more easily than reciprocating compressors. This has to do with differences in the inlet/outlet pressures both of which tend to fluctuate with LPG extraction systems as recovery progresses to completion, tank pressures rise/fall and vapor assist is applied at various points in the cycle to encourage fluid flow to flood columns.
I eventually landed on the oilless reciprocating design (blackmer/corken/etc.) because there is pretty much none of the aforementioned issues to deal with. No separator required, no working fluid except the oil in the crankcase which is very simple to deal with, uses very reliable hydrodynamic bearings and can handle a highly variable pressure ratio across the compressor.
Furthermore, if you guys are getting to the point where you need CFM capabilities in the neighborhood of 100CFM or more I would suggest looking into the horizontal oilless reciprocating designs.
Horizontal reciprocating designs have an advantage over the vertical designs in the sense that the pistons are double acting, meaning the piston does work to the fluid on both sides of its stroke as seen in the upper left corner in the pic below. This allows much higher pumping capacities for a given pump size.
The largest model horizontal Corken has a claimed 414 CFM or 704 m3/hr in a fairly compact single unit.
4 Likes