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Solvent recovery and chemical disposal can become an expensive yet unplanned cost for solvent processes like vapor degreasing. Solvent recycling equipment can separate and remove soils, debris and oils from solvent through a process called distillation. These used solvent recovery systems can recycle most cleaning solvents, reduce solvent purchases by 95%+ and chemical waste disposal cost by 90%+.
Most solvents can be recycled and recovered with solvent recovery equipment including:
- Mineral spirits
- Paint Thinner
- Acetone
- IPA (isopropyl alcohol)
- MEK (methyl ethyl ketone)
- Xylene
- Hexane
- Various alcohols
- Chlorinated solvents (AK225, 1,2 trans-dichloroethylene / trans DCE, 3M Novec, Dupont Vertrel)
- Microcare solvents
- Terpenes Toluene
- Aromatic Solvents
In addition, Class 1 Division 1 NFPA solvent recyclers can be used to ensure safety for flammable solvents.
Solvent recycling equipment can recycle nearly any solvent or chemistry used in electroplating, metal finishing, paint and powder coating, parts washing, and vapor degreasing.
How Does a Solvent Recovery System Work?
Solvent recovery systems use the process of distillation, which separates volatile and nonvolatile solutions in a solvent. The solution is boiled and the vapors are condensed back into liquid in a separate tank, very similar to how a vapor degreaser works. The various constituents of the solvent and contaminants each boil at different temperatures: typically oils and soils are much higher than solvents. A good example of this is paint thinner which is used to clean paint off paint guns and parts; the solvent will boil at much lower temperatures than paint, so boiling the mix will result in condensed pure solvent in a separate tank and the paint sludge components in another.
Simple vs. Fractional Distillation and How to Separate Multiple Solvents
The above description and solvent recycling example is of simple distillation which aims to separate one solvent in solution and recovers the majority of the solvent in solution. Simple distillation entails condensing hot boiled vapors directly from the boiling tank of the solvent recycler. Because the condensing occurs directly near the boil “sump,” only one volatile solvent can be recovered and the purity of the solvent may contain very small amounts of non-volatile contaminants carried with the boiling, volatile vapors. This is the same process used by vapor degreasers. While recovery of a single volatile solvent can reach 99%+, there are times when higher recoveries are necessary.
When higher purity recovery or two or more volatile components (ie. water and isopropyl alcohol) require separation, fractional distillation is required. Fractional distillation uses a reflux column between the boiling tank and the condenser coils to achieve higher purity solvent recovery and separation of different volatile solvents. This process can achieve 99% solvent recovery and solvent purities of over 99.9%, often required for electronic / PCB manufacturing, medical device and aerospace applications.
Vacuum Assisted Distillation
Putting a vacuum on the distillation column and chamber can be required for higher boiling and heavier-than-air (higher vapor density than 29 AMU – atomic mass units) solvents such as xylenes, CFCs, etc. vs. lighter-than-air acetones, MEK (Methyl ethyl ketone / butanone), MPK (Methyl n-Propyl Ketone), alcohols, etc.
Used Solvent Recovery System and Recycling Waste Solvent Benefits
- Reduce virgin solvent purchases
- Reduce solvent chemical waste
- Reduce effects on hazardous waste generator permit status
- Lower storage costs
- Obtain quicker ROI on capital equipment when using safer yet more expensive engineered solvents like Dupont Vertrel or 3M Novec engineered fluids.
Inline Vapor Degreaser Integration
While vapor degreasers inherently distill solvents, further distillation of just the vapor degreaser boil sump can extend the life and reduce consumption of solvents. Automated integration of a solvent recovery system with a vapor degreaser is typically very simple, with no vapor degreaser modifications: pull from the drain of the boil sump and exit distilled solvents into the rinse sump or water separator. Waste is then stored in the solvent recycler for easy disposal. This permits continuous use of the degreaser without down time to clean the boil sump. With solvent recovery systems, solvent boil down and change-out intervals can be increased by 200%.
Solvent recycling and recovery systems can greatly reduce costs, hazardous waste disposal, and solvent consumption while increasing process stability and operation.
