The solvent passes through a water separator and can be reused. Steam is used to heat spent solvent to its boiling point. The residue left in the still, called sludge or still bottoms, must be disposed of as hazardous waste. To extract even more solvent from the sludge, add water to the still bottom or cooker following the final boil down or cook down. Talk to your equipment supplier for more information on how to do this for your specific type of still.
Steam regenerates the solvent from the carbon bed.
The steam-solvent vapor mixture condenses, and the solvent and water are separated. Otherwise, it must be disposed of in an acceptable manner. Condensers are equipped with a refrigeration unit to increase the condensation efficiency. Air containing solvent from the dry cleaning machine is fed into the unit and forced over a series of very cold baffles. The stripped air is returned to the dryer, while the condensed vapor drains to a water separator.