1-805-484-2992
Quotes - Engineering - SalesThree solvents, three flowsheets
Pick the solvent, and the exchangers follow
A processor chooses hydrocarbon for terpene-rich concentrates, ethanol for throughput and distillate, or supercritical CO2 for a solvent-free label, and each comes with a different set of exchangers. Hydrocarbon lines chill propane and butane to -40 to -80 F and recover the solvent on a chilled condenser. Ethanol lines chill, evaporate and condense. CO2 lines run the solvent through a heater into the vessel and through a separator and a condenser back to the pump at 1,000 to 5,000 psi.
Post-processing is common to all three: winterization, decarboxylation at 220 to 250 F, and distillation with a condenser on the vapor. The ethanol flowsheet in detail is on the CBD Extraction page.
Hydrocarbon, CO2, post-processing and the classified room
Hydrocarbon lines: chill, extract, recover
Butane boils at 31 F and propane at -44 F, so a hydrocarbon line stores the solvent under its own vapor pressure and chills it to -40 to -80 F before injection to keep terpenes and leave waxes. The chiller is a shell-and-tube on a low-temperature fluid at -90 F, rated for the solvent's vapor pressure at the warmest temperature it could see, about 175 psig for propane at 100 F. After extraction the solvent is boiled off the extract in a jacketed collection vessel at 90 to 100 F and the vapor goes to a recovery condenser, a shell-and-tube with hydrocarbon in the tubes and chilled fluid at 0 to 20 F on the shell, which liquefies it back to the solvent tank. The condenser sets the recovery rate; an undersized one turns a 30 minute recovery into two hours.
CO2 lines: heat, separate, condense
Supercritical CO2 runs at 1,500 to 5,000 psi and 90 to 120 F through the biomass, drops pressure in one or more separators where the extract falls out, and returns the CO2 to a condenser at 40 to 60 F and 600 to 900 psi for the pump. The exchangers are a preheater ahead of the vessel, cooling on the separators to control what drops out, and the recycle condenser. Every one is a pressure vessel first: a coil-in-shell or small shell-and-tube rated well above 5,000 psi on the CO2 side, ASME stamped, in 316L. The duties are small and the design is about pressure, not cleanability.
Decarb and distillation condensers
Decarboxylation heats crude to 220 to 250 F for an hour or more in a jacketed reactor on hot oil or 60 psig steam, with a small condenser on the vent that catches terpenes and water driven off. Distillation, wiped-film or short-path, runs at 300 to 400 F under deep vacuum with an internal condenser fed by a circulating heater-chiller. The external condensers on these steps are small vertical shell-and-tube units on tower or tempered water, sized on the vapor rate the reactor vendor states with a generous sub-cooling section, because a decarb condenser that lets terpene vapor past it makes the room smell and loses product.
The classified room and the common mistake
Hydrocarbon extraction is done in a Class I Division 1 room and ethanol in Class I Division 2. A heat exchanger has no electrical parts, but the skid, transmitters, valves and chiller are classified, and the exchanger is specified with them in mind: no elastomer that ethanol or butane swells, no aluminum in a propane line, clamps rated for the pressure, and full drainability so solvent does not sit in a shell after shutdown. The common mistake is a plate exchanger on a hydrocarbon duty: the gasket seam is a leak path for flammable gas under pressure and most jurisdictions will not accept it. Hydrocarbon exchangers are welded shell-and-tube.
Send the solvent, the recovery rate, the vessel ratings, the chiller fluid and the room classification and HeatX quotes the set. Call and talk it through with an engineer: 1-805-484-2992
Cannabis extraction process conditions by solvent
The solvent sets the build, so each row is read by solvent: hydrocarbon, ethanol or CO2. Find yours, compare it with your room classification and send both with the quote request.
| Condition | Detail |
| Product | Propane and butane blends; ethanol; CO2 at supercritical conditions; crude and distillate downstream |
| Flow range | Hydrocarbon recovery 20 to 200 lb/h; ethanol 5 to 60 gpm; CO2 10 to 100 lb/min |
| Temperatures in / out | Hydrocarbon chilled to -40 to -80 F, recovered at 90 to 100 F; CO2 heated to 90 to 120 F, condensed at 40 to 60 F |
| Hold | Vessel residence 5 to 30 minutes; decarb 60 to 90 minutes at 220 to 250 F |
| Utility | Low-temperature fluid to -90 F for hydrocarbon chillers; chilled water for CO2 condensers; hot oil or steam for decarb |
| Approach | 10 to 15 F on cryogenic chillers; 5 to 10 F on CO2 condensers; 20 F on decarb heaters |
| Construction | Shell-and-tube for hydrocarbon at pressure; plate for ethanol; coil or shell-and-tube rated 5,000 psi for CO2 |
| Finish / class | 316L product side, 32 Ra; food-grade gaskets; pressure rating per the solvent, ASME stamp on hydrocarbon and CO2 vessels |
| Area classification | C1D1 for hydrocarbon rooms, C1D2 for ethanol, unclassified for CO2 |
| CIP | Solvent flush between runs; periodic hot ethanol or caustic clean |
Common FAQs
A silicone-based or hydrofluoroether fluid on a cascade chiller; glycol is out below -50 F.
Not in most jurisdictions and not by HeatX. Gasketed plates leak at the seam; hydrocarbon duties get a welded shell-and-tube rated for the vapor pressure with margin.
The CO2 side needs pressure integrity, not polish. The separator and downstream extract handling are where food-grade surfaces matter.
Ethanol, because it is chilled and evaporated in bulk. Hydrocarbon has a smaller chiller and a critical recovery condenser; CO2 has several small high-pressure units.
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