What Is Solvent Distillation?

Posted by Larry Burton on Jun 21, 2016 4:00:00 PM

Our web page on solvent distillation spells out a very good explanation of exactly what solvent distillation is and how the entire process works. Here is what is says:


Solvent Distillation is Defined as:

“A process in which a liquid or vapor mixture of two or more substances is separated into its component fractions of desired purity, by the application and removal of heat”. 

Temarry-Recovery-Stills.jpgSolvent Distillation Recovery is based on the fact that the vapor of a boiling mixture will be richer in low boil point components such as acetones, ketones, aliphatic hydrocarbons and alcohols. 

When vapor is cooled and condensed, the liquid condensate becomes a valuable product that can be sold back into the industrial market place. The higher boiling point portion of the original mixture that does not vaporize remains in the bottom of the recovery still. This portion is valuable as a fuel source for certain industries like cement kilns to recover the heat value. 

Solvent recycling is preferred to other disposal methods for minimizing adverse environmental effects. Distillation is the most common method of solvent recycling, although filtration can be used to remove solids and nonmixable liquids.

 

What Types of Solvents Can Be Recycled?

Many solvents can be recycled, reprocessed, and then reused. The most commonly recycled solvents are:

  • Aliphatic
    • Mineral Spirits
    • Naphthas
  • Aromatics
    • Toluene
    • Xylene
  • Halogenated Hydrocarbons
    • Fluorocarbons
    • Methylene Chloride
    • Perchloroethylene
    • Trichloroethylene
    • 1,1,1 Trichloroethane
  • Alcohols
    • Isobutyl Alcohol
    • Isopropyl Alcohol
    • N-Butyl Alcohol
    • Methanol
  • Ketones
    • Acetone
    • Methyl Isobutyl Ketone
    • Methyl Ethyl Ketone
  • Esters
    • Ethyl Acetate

 

On average, for every 100 drums of solvent that Temarry receives 70 drums of useable product are produced and sold back into industry. The remaining 30 drums of still bottom waste are blended to be used as fuel at a cement kiln. The result is that 100% of solvents that Temarry receives are recycled. Because energy in the form of steam is produced from an onsite Waste to Energy process,

Temarry is the only Closed Loop Recycling facility serving the western U.S.

 

Do Different Waste Solvents Need To Be Stored Separately? 

There is no benefit for the generator to store or accumulate solvents separately. Often times solvent products purchased are a blend of different solvents listed above. For example, Paint Thinner can be a blend of aliphatic, aromatics, alcohols and ketones in various percentages. If a generator has various flammable solvents used in different processes they can be kept separate or accumulated together in the same container. It makes no difference in the solvent recovery process.   

 

Should You Perform Your Own Solvent Recycling?

How hard can it actually be if you’re only boiling off liquids? Apart from all the federal and state environmental regulations, permits and approval processes your business would need to wade through, the cost of purchasing and operating a recovery still, would more than likely, be cost prohibitive.

If you are considering doing your own solvent recycling here are a few items to consider when making a potential capital investment.

Initial Capital Investment

  • Equipment Cost
  • Shipping
  • Training

Annual Operating Expenditures

  • Labor
  • Electricity
  • Maintenance
  • Cooling Water
  • Costs of Manifesting left over waste products

 

All of these costs may be achievable for your business, however, you also need to consider your own States regulatory guidelines for operating a recovery still.

Using it becomes the issue.

A small recovery still with a 10 to 20-gallon capacity is exempt from most permits for onsite use only. They will have to know and understand the requirements of state, county, city and fire districts for their location. That can be very cumbersome.

With the current environmental climate the way it is, it makes more sense these days to use facilities that specialize in the solvent distillation process, have already gone through all the bureaucratic red tape and are experts in transporting and disposing of your waste. It’s not just a good financial decision, it is a good business decision.

 

Solvent Distillation and Energy Recovery Process

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