They have it setup with dedicated valves and heat exchangers for each leg which requires the operator to manually switch between the active and passive legs.
Iām thinking you could add a one-way check valve with 5-10 PSI cracking pressure to the passive leg, remove the control valves and just feed both legs into the same heat exchanger and not have to worry about switching between them.
This is pretty much an active recovery setup with a bypass and check valve around the pump.
When the differential pressure between the collection and solvent tanks is above the cracking pressure of the check valve, the passive leg will operate automatically when needed and the recovery pump can operate continuously.
I think this design offers max efficiency but I personally donāt have too much time on my system when the tank pressures would operate the passive leg so Iām not sure if the added complexity maxes sense for a small increase in efficiency.
Can anyone point me at the maths for how many BTUs (or other more appropriate unit of measure) to calculated how much heat energy I have to dump in a CLS water bath to keep my water temp up to @120F. Iām running a passive system.
The system is:
4"x48" material column
1/2" JIC hose to
6"x36" fully jacketed dewax spool w/ 3 - 6" filter plates at bottom
1/2" JIC hose to
12"x12" shatter platter (not jacketed) in waterbath (non circulating )
1/2" JIC hose to 3x12 spool of mol seives to 1/2" hose to 120lb recovery/injection tank with internal condenser coil and full jacket.
Solvent is Isobutane pure 99.something percent instrument grade (usually), just switched gas suppliers, used to get it from Matheson before they stopped selling it last year. but always iso, no blends.
Iām running LN2 through the jacket on the recovery tank and outside for now, because of the massive ā²T the hot water bath is cooling too fast and Iām not getting enough vapor pressure to move as fast as I should be able to.
I do not own this machine, I just started running it for a friend, it is pretty janky right now, Iām working on getting a jacketed base and a jacketed material spool as well as trying to design a chiller that uses LN2 to chill a thermal exchange fluid (I am considering methanol as it is cheap, has good thermal transfer properties and is easily pumped at -100C) still looking into safety on this issueā¦
So Iām in need of the maths that ultimately calculate how many watts I have to my heater needs to keep water hot. or even just the math for how much heat is being moved per rate of evaporation.
Thanks in advance for everyone in this community, Iāve spent 60-80hrs researching in the last month or so and this site has been a fundamental part and itās members have provided wonderful insight and info on how to operate well at almost any scale.
Thanks, thatās a nice spreadsheet of some of the values I need.
Iām looking more for the formulas I need to use to calculate how much heat I need to add or how many btus of heat need to be removed from the system including the latent heat from phase change and loss of efficiency to the environment
Simple math is what I use
I know the volume I need to evaporate
So that times their liquid and vapor enthalpy is the amount of heat I need to ad at my desired pressure /temp
I know the heat transfer numbers on my jackets and coils so I know there rates
I don t know my losses to surroundings
But I add 20% for insulated jackets and piping
Thatās exactly what I was looking for, the abstract calculations (simple math) to start narrowing in on what is a complex issue with many variables.
One of my biggest challenges is that there are no temp probes anywhere in the system, so Iāll have to use a non contact thermometer and guess.
honestly I could just buy an electric home water heater and a boiler circulator as Iām sure that there is more than enough heat energy in a unit that size. Iām more interested in figuring out how to calculate the basic overall energy gains and losses in the system because the owners have a much poorer understanding of physics than they believe and Iām just some guy with ass-burgers (thatās what I call HFA) and no degreesā¦ but I can assure you that I understand far more about how all this shit works.
Math is a good language to show people how things actually work in my experience.
I am going to do this, I looked into the rate that i should be able to move gas at through a 1/2" line vs dual vs 1.5" hardlineā¦ seem that this isnāt my main issue currently as even with one 1/2" line the possible throughput was insane like ā30lbs/minā or something way outside of current realworld parameters in this case. It is a good solution however I would have to add an external coil as the current setup has an internal coil in the solvent tank
excellent point. I assume that I can tweak that once I know how much pressure is being lost due to evap when I can measure how fast the collection pot is losing mass
I use a modulating butane/propane heater of 32kw on a 240L collection pot
Even with a jacket and internal coil I had isseus to keep the 12cfm corken fed and 45psi in the pot
I solved this with welding a ss coil to a 6" >1 1/2" endcap with two 3/8 ports
The coils entry and exit for water
This I placed at the botom of my collection pot and use the 1 1/2" as connection to my honeypot
I manage to ad an additional 6 kw of heat to my solvent
Dry ice is not the only way to use a passive set up, it is in fact much more expensive than cryo fluids or refrigeration solutions, so once you get out of the dry ice is expenive box, you may find that there are many advantages to passive at most if not all scales
Internal so a 4" diameter 24" high coil standing smack in the middle from the botom up
Because it stands 4 " from the botom and I have the honey pot
I don t get fouling on the coil and by taking of the 6" plate I can take it out for cleaning
Wouldnāt matching the heating and cooling with the correct amount of kw, with passive recovery with 1/2" ports all around make it more effective than active? Like isnāt passive mainly about temperature differences pushing the solvent? So wouldnāt sufficient vapor generation and a larger orafice for the vapor to travel thru be more effective?
What if your running 1/2 revovery active? Or 1 in?
Ultimately depends on the pump. A t90 is slaying speeds.
Passive optimized goes fast tooā¦ The thing is at what cost per run. If your using chillers and not comsumables like dry ice, you already dropped some loot for chillers. Assuming we are talking about large systems where passive just doesnāt make sense because of the cost of said chillers.
So run expensive dry ice, or expensive chillers, with lc02 or something similar.
Or a recovery pump where depending on which pump can get you āfast enoughā to āpassive could never do this for this priceā
Passive effective? Definitely.
Passive cheaper at larger scales? No
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