ETHANOL PRODUCER'S DATA BASE

• Before mixing Ethanol to Gasoline,
  • it is necessary to dehydrate it to 199 + Proof
• Here is an overview of the methods that may be adapted to small operations.
  • Corn Grits
  • Rock Salt 
  • Salting out experiment
  • Lime
  • Castor Oil
  • Molecular Sieves
  • Molecular Sieves Analogy ( Molecular Sieves Explained )
  • Model of the surface of a Zeolite Bead
  • Zeolite Dehydartion Technique for Small Producers
  • Pressure Swing Adsorption
  • Contamination

• Water dissolves in rock salt
• Ethanol does not.
• Water can be removed  by circulating the Ethanol / Water through dry salt.
• Rocksalt, such as used in water softeners is readily available, and low in cost.
  • The rocksalt can be dried and used many times.
  • Hygroscopic (water absorbing) material such as calcium salt will work.

However, common rocksalt, such as used in water softeners is cheap and available. Remember that the salt must be dry. After absorbing water from a certain amount of alcohol, the salt must be re-dried.

1. Fill an  empty  1 liter jar 1/4 full with table salt

2. Fill the jar about 3/4 full with 160 Proof Ethanol

3. Close lid to seal the contents 

4. Shake jar vigorously to be sure the salt and water combine.

5. Stand  jar on a table  for 30 minutes

   1.  and salt water to fully separate

   2. The dividing line is clearly visible

6. Siphon the Ethanol from the top

7. Poor out the water laden salt on a cookie sheet

8. Oven dry the salt at 300°F for 1 Hour

   1. Or lay it in the sun until the salt is completely dry

   2. The salt can be re-used indefinitely 

• Based on this simple experiment, you can then model a process
  • that will dehydrate your ethanol very efficiently.
  • No matter what size is required

• The oldest method of drying alcohol is dehydration with lime.
• This process is still used on a laboratory scale. It is similar to the salt absorption method just described except that, with this method, water is removed by a chemical reaction.
• Ordinary lime (calcium oxide, formula CaO) reacts with water to form calcium hydroxide (formula Ca(OH)2).
• The process is simple.
• The water-containing alcohol is mixed with lime at a ratio of about 35 pounds (or more) of lime for each gallon of water to be removed (as determined with a hydrometer) and allowed to “slake" for 12-24 hours with occasional stirring .
• The lime reacts with the water to form calcium hydroxide.
• The calcium hydroxide is insoluble in the alcohol and so the relatively pure (99.5%) alcohol goes to the top of the container and the calcium hydroxide settles to the bottom.

• The usual method of separating the lime and calcium hydroxide from the alcohol is by distillation.
• Alternately, but less desirable, the alcohol can be carefully drawn off (decanted) and filtered to remove any suspended particles that give it a milky appearance.

• An apparatus based on a 55-gallon drum can be built.
• A still head with thermometer (no reflux column is needed) and condenser should be added to allow simple distillation.
• Also, a small gate valve located 6-8 inches from the bottom (above the level of the lime) will allow the alcohol to be decanted, if desired.

• After slaking in the apparatus, the alcohol should be distilled off through the simple still head and condenser.
• During distillation, the temperature should remain exactly at the boiling point of pure alcohol.
• Remaining after the pure alcohol has been distilled or decanted is wet calcium hydroxide and lime.

• Some alcohol will also be trapped in the residue.
• To recover it, continue the distillation.
• The still head temperature will rise above 173 degrees F indicating that water is coming over with the remaining alcohol.
• When the still head reaches 208-212 degrees F all of the alcohol has been removed.
• The water/alcohol distillate should be added to the beer for the next run in the reflux distillation apparatus.

• The calcium hydroxide may be converted back into calcium oxide and re-used.
• However, the temperatures required are quite high unless a vacuum drying oven is used.
• Since lime is relatively cheap, this process is not recommended.
  • SOURCE: Mother Earth

Solubility" (LAR-14894), the proposed alcohol/water separation process could be exploited industrially to produce clean fuel from fermented vegetable matter.

In one version of this process, castor oil would be added to an ethanol/water solution. The ethanol would mix freely with castor oil, which is insoluble in water. The resulting ethanol/castor-oil phase, which would contain less than 1 percent water, would collect as the top layer, the bottom layer being the remainder of the ethanol/water solution somewhat depleted in ethanol. Heating this two-layer mixture to a temperature slightly below the boiling temperature of ethanol (78.5 °C) would cause the partial pressure of ethanol above the top layer to be much greater than the partial pressure of either castor oil or water. This vapor-phase ethanol could be condensed in a relatively pure state.

Although heating an isolated ethanol/water solution like that in the bottom layer would normally raise the vapor pressure of both ethanol and water above the solution, this would not be the case in the presence of the top castor-oil/ethanol layer for the following reasons: The amount of water that could dissolve in the top castor-oil/ethanol layer would increase only slightly upon heating. On the other hand, ethanol could readily cross the interface between the two layers and enter the top layer. As long as the total mix was kept at a temperature below the boiling temperature of ethanol (thereby preventing agitation of the layers by boiling), the diffusion of water through the castor-oil/ethanol phase would be inhibited.

In an alternative version of this concept, the upper castor-oil/ethanol layer would be skimmed off and heated to obtain the ethanol. Once the ethanol was driven off, the castor oil could be returned to an ethanol/water solution to dissolve more ethanol to repeat the process. This concept could readily lend itself to a continuous process. Substances other than castor oil (one of its components perhaps, or another substance) could be used in this process or to extract other compounds from other mixtures by using this upper-of-two-phases vaporization technique.

Source: This work was done by Renaldo V. Jenkins of Langley Research Center.

No further documentation is available. LAR-14895

DEFINITION:

A 'molecular sieve' is a material with selective adsorption properties capable of separating components of a mixture on the basis of a difference in molecular size and shape.

APPLICATION:

 In dehydration of ethanol, 3A Zeolite is used to absorb the water content from the ethanol.

• Ethanol molecules are 4.4 Angstroms in diameter.
• Water molecules are 2.8 Angstroms in diameter.
  • It is this size-sorting property of the zeolite that is responsible for the “sieve” term.
• Molecular sieve adsorbents are crystalline alumino-silicates.
• Their unique structure allows the water of crystallization to be removed, leaving a porous crystalline structure.
• These pores or "cages" have a high affinity to and re-adsorb water or other polar molecules.
• Aided by strong ionic forces (electrostatics fields) caused by the presence of cations such as sodium, calcium and potassium, and by the enormous internal surface area of close to 1'000 m2 / g, molecular sieves will adsorb a considerable amount of water or other fluids.
• If the fluid to be adsorbed is a polar compound, it can be adsorbed with high loadings even at very low concentrations of the fluid.
• This strong adsorptive force allows molecular sieves to remove gas/liquid impurities to very low levels (PPM or less).
• Another feature of molecular sieve adsorbents is their ability to separate gases/liquids by molecular size or polarity.
• The pore or "cage" openings are of the same size as many molecules.
  • E.g. in the case of hydrocarbon paraffins, the normal, straight chained molecules can fit into the pores and be adsorbed while the branched chain molecules cannot enter the pores and pass by the molecular sieve adsorbents un-adsorbed
•  Molecular sieve adsorbents product range includes all commercially used types, such as 3A, 4A, 5A and 13X, as well as several special types, formulated for specific applications.
• For typical characteristics, chemical and physical properties of the various molecular sieve adsorbents and further information on their nature, applications, [follwo this link]

   

MOLECULAR SIEVES EXPLAINED

These beads are like sponges that are full of holes, and are made so that the holes have a rather narrow range of sizes, just the right size to hold water and let ethanol roll off the surface..

• Let’s consider a working analogy: Using Marbles and beans…
  1. Take a liter or so of marbles, say 1/2” ( 12MM)
  2. Take a liter or so of dry beans ( Roughly 1/3 the size of the marbles )
  3. Mix the two in a bucket.
  4. Fill a clear 6” ( 150MM) plastic cylinder full of sponges. 
  5. Fit the bottom of the cylinder with removable bottom.
     1. Select sponges that have holes sufficiently large to hold the bean.
     2.   And let the marbles roll off their surface.
  6.  Dump the bucket of marbles and beans in the top of the cylinder.
  7. Shake the cylinder to cause the mixture to run down the cylinder. 
     1.  Watch the marbles bounce off the sponges.
     2.  Watch the beans get caught in the holes at the surface of the sponges.
  8.  Now, take the lid off the bottom, and remove the marbles.
     1. Note: Some beans will have made it to the bottom…
     2. Some marbles will have been caught up in some larger hole in the sponges…
     3. Exactly as happens in real life Zeolite dehydration: A little water and Ethanol remain mixed.
• You don’t have to actually construct the above cylinder and purchasse marbles and beans to fully understand the analogy,
• Your imagination can save you $$.

Photomicrograph of the surface of a zeolite bead showing the chrystals with holes between the chrystals providing the right space to grab and hold the smaller water molecules. Letting the larger Ethanol molecules slide off the surface of the bead.

• This is not an actual Ethanol Dehydration Zeolite, however it is the same.
• The surface has the ability to retain the water molecule
• [SOURCE]

Photomicrograph of the surface of a Zeolite bead showing the christal like structure which provide the right space to grab and hold the smaller water molecules. Letting the larger Ethanol molecules slide off the surface of the bead.

• This is not an actual Ethanol Dehydration Zeolite, however it is the same.
• The surface has the ability to retain the water molecule
• [SOURCE]

• The zeolite has a maximum amount of water that it can hold, if you
  incorperate it into the distilling process then you will load it up
  while the alcohol is still quite wet and thus making it unproductive.
• For 10 pounds of zeolite your maximum benefit would be to distill
  your alcohol to 195 proof.
• Pre dry your zeolite and then while still dry
• Pour about 3 gallons of alcohol into it.
  • (14 pounds per 5 gallons is what the mfgr told me.)
    
    
• wait about 20 minutes and then
• Pour off your 200 proof alcohol and
• Store in an air tight container.
  • You will find you do not get all 3 gallons back,
  • in fact you will only get maybe 2,
• The rest of the alcohol is still stuck inside the
  zeolite in the little particles that are to big to push the alcohol out.
• Now you need to recover the alcohol out of the zeolite before
  you dry it or you will loose the alcohol, not good!!!
• To recover your alcohol, pour the zeolite full of water, just enough
  to cover it. the water will push out the rest of the alcohol,
• Wait about 20 minutes and then
• Drain your alcohol/water mixture out and
• Put it into the next batch of beer that you are going to distill.
• The zeolite can now be dried for reuse.
  
  A lot of work I know but this is the only way to do it right now
  until you are ready to build a drying tower.
  I have not seen a good design for a drying tower but I know that
  there are a few members working on them.

 [Source: Donald Franson from Alcohol-fuel Forum]

• Zeolite must be kept very dry between uses,
  • if not, it may become contaminated and will have to be replaced with fresh dry Zeolite 

The following comment from Peggy G.Korth illustrates this very well. 

• Think of the spounge that is kept in the kitchen sink.  
  • Although those people that like to use spounges understand the necessity for completely drying a spounge after washing with one to reduce the impact  of contamination,
• That spounge can come up with some strange odors.  
  • If/ when this happens, it should be discarded.
    • ( or soaked in bleach water and dried.)  
• I am not aware of a 'fix' for contaminated zeolite.  
  • And if and when we find one, it may serve as a denaturant.  
    • (Just a thought with a huge warning about toxicity).  
• Waterborne microbes are primal in microbial development and the assumed first step in our earth's life cycle development.
  • Source: Peggy G Korth