Struggling with flow on my 10lb closed loop

Hash and Stuff Extraction
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Hey guys me again, im struggling with flow in my cls .

So I followed the process from the gas cylinder to the material columns, that part runs perfectly, but my problem is from the columns to the collection chamber i get the gas flowing up then it dribbles out a few drops then stops …please help me with this bottle neck . Nitrogen push helps it but then it leaves some gas left in the gas cylinder…

Pressure test and vacuum test done , no leaks at all

The jacketed collection vessel do I start it off cold or heat it up from the start ?

Note this is passive still waiting for my haskel pump to come

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You can heat it, but you’ll need to recover while you’re injecting to relieve pressure, or increase N2.

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Can the vapor lock be from opening the material columns separately instead of simultaneously? There is a vacuum on the whole system and i left the heater off while running and still nothing without n2 , last question if my gas is -20 do I still need to dry ice my columns? Fast push

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Once the headspace in your collection equalizes with the headspace in your solvent tank, liquid will no longer flow. Media can slow or stop flow as well. To overcome this, you’ll need N2 or a warm vapor loop (less ideal), if recovering to relieve pressure is not enough.

-20°C is pushing it. You can make decent extract with -40, if you move fast. You’ll have noticeably better results if you chill your material columns, though.

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Without N2, OR a pump, the only pressure differential you’ve got is the vacuum you pulled on your collection. If you start with it warm, you loose all of it the moment solvent hits…

Same applies to getting solvent into your column

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Captain Safety Pants here, can we get someone on a call with OP to work this out? There is a giant pipe bomb involved.

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Vapor likes chasing cold and low pressure. Put the collection in dry ice alcohol slurry or have coils submerged in dry alcohol slurry before collection. The vapor chasing the cold will chill out condense and keep on flowing

Or if you are working with just n butane you can use regular ice water and salt

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I can count at least a handfull of operators down here that all hit this snag for exactly this reason. Like the sands through an hour glass, these of the days of our lives.

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This is something I’ve always been on the fence about.

I’ve run a lot of live resin without actively chilling the material columns. I would pull the socks/columns from the freezer, load them and flood immediately with cold solvent. Since it only took a minute or two to flood a column and I wasn’t soaking, there wasn’t much time for the material to warm significantly.

I used bare un-jacketed columns, then heat mats with Velcro straps during column recovery.

I can see active column cooling mattering more with slower floods, long soaks or a process where loaded columns sit for a while. But with a fast, no-soak workflow, it always seemed like a lot of added equipment and energy (and cost) for very little practical benefit, especially at scale.

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You’d be surprised how much warming occurs from the time cold solvent is introduced to the time the last bit of solvent leaves the material column, even without a soak period, especially with un-jacketed columns.

From a purely theoretical perspective I can think of three mechanisms that lead to substantial heat gain—consider that the stainless spool is the thermodynamic boundary:

  1. Heat gain to solvent due to equilibration of column to solvent temp (biggest driver)
  2. Heat gain due to latency from filling up and draining column (medium driver)
  3. Enthalpy of solution for dissolution of cannabinoids, etc in solvent (almost negligible)

Assumed Variables:

Column OD = 6" =0.152 m

Column Length = 48" =1.219 m

Column Thickness = 6mm =0.006m

Density of Stainless Steel = 8000 kg/m3

Heat Capacity of Stainless Steel (c_ss) = 0.5 kJ/kg*K

Heat Capacity of Butane (c_but) = 2.3 kJ/kg*K

Heat Capacity of Biomass (c_bio) = 1.5kJ/kg*K

Volume of Stainless Steel Column = V=piL(r_o^2-r_i^2) = 0.00336 m^3

Mass of Stainless Steel Column (m_ss) = 27kg

Mass Butane (m_but) = 12kg

Mass Biomass (m_bio) = 5kg

Solvent/Biomass = -40C

Ambient/Stainless Temp = 20C

Part 1

C_ss = c_ss * m_ss

C_bb = (c_bio * m_bio) + (c_but * m_but)

T_f = ( C_ss*T*_ss,0 + C_bb**T_bb,0 ) / (C_ss + C_bb)

T_f = -21.2C (47% increase in temp)

Part 2 (lol)

assuming 5 mins to inject and transfer to collection

Convective Heat Gain = Qcon = hAdT

(dT in this case is just the temp difference between the ambient surroundings and the solvent/biomass—since the temp of the solvent is differential due to what was shown in part one, just assume an average for a more accurate calc—so instead of a 60K difference, it’s closer to 50.5K)

h = 5 - 10 W/m^2*K

A = pi*ODL + 2pir^2 = 0.6205m^2

Qdot_con = 298W

Qcon = 298W*5min = 89.4kJ

Radiative Heat Gain…I’m tired of typing shit out, it’s getting ridiculous, just trust me, is 14.1kJ

Qtot = Qcon + Qrad = 89.4 + 14.1 = 103.5kJ

Change in Temp from Conv+Rad = 103.5kJ/C_ss + C_bb = 2.1C

T final final =- 21.2 + 2.1 = -19.1C

This is all theoretical, but you can assume that it’s a bit more considering that frost increases heat flux over time, the differential effects intensify the heat gain

IME I’ve injected -40C solvent and gotten close to 0C by the time it was in collection

$0.02

P.S. excuse any math errors, the formulas should be right though

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Have you tried adding a valve you can open to bleed off pressure build up while going from your material columns to collection vessel? Sounds to me like your pressures are equalizing hence the slow down and dribbles. Or dont turn on your hot water on the collection until you finish dumping your material columns. The heat will build pressure too once the butane starts evaporating.

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Problem and solution. Assuming you’re using the pump to recover gas from the collection, you’ll reduce the pressure on one side, allowing flow from high (material) to collection (distillation).

N2 works, but much more efficient (imo) to just have a recovery loop or vessel to drop pressure in the distillation as opposed to shoving more PSI into it.

The vapor lock is from not having a way to recover solvent in the collection, or from not having enough PSI to overcome the pressure from distilling/warming butane gas in the collection. I run at -50 from tanks, -40 in soak, and it’s upwards of -20/-10 by the time it hits and passes the CRC; These are just ballpark numbers from an IR gun one day last week.

Unjacketed columns will warm up your tane substantially and exacerbate the pressure lock issue. As stated, the best solution is to recover, but more N2 will probably do as well.

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Have you checked if there is any restriction between the material columns and the collection chamber?

Sometimes a system can pass pressure and vacuum tests but still have flow issues if there is a partial blockage, especially around screens, filters, or small passages where material can accumulate.

It may be worth checking the condition and micron rating of any inline screens/filter elements in that section. A restriction there can allow pressure to build but limit actual flow.

Also curious — does the flow improve when the collection vessel temperature changes, or is it the same regardless?

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Vent to atmosphere , jk recovery is the only option I would just hookup another vessel and have it vacuumed down and crack that -30 when you inject.have it in it dry ice or a slurry if you want to

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Thank u so much everyone, all sorted, threw a hot cold bath circulator on the collection vessel, and pushed with n2 . Flow for days thanks to this platform, and u all that guided me in the right direction. Forever thankful :folded_hands:

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