Depending on what you are distilling (fruit, grains, flowers, crude and derivatives etc.) a mixture of different chemical substances will be obtained in the distillation process.
If the intention is to obtain alcohol fit for human consumption, independently of what is being distilled, what we want is the ethanol alcohol.
The different chemical substances in a batch (liquid or matter being distilled) begin to vaporise (their boiling point) at specific temperatures.
If isolated these would be:
Acetone 56.5 ºC (134 ºF) Methanol (wood alcohol) 64 ºC (147 ºF) Ethyl acetate 77.1C (171 ºF)
Ethanol 78 ºC (172 ºF)
2-Propanol (rubbing alcohol) 82 ºC (180 ºF) 1-Propanol 97 ºC (207 ºF) Water 100 ºC (212 ºF) Butanol 116 ºC (241 ºF) Amyl alcohol 137.8 ºC (280 ºF)
Furfural 161 ºC (322 ºF)
However, as the different substances are not produced separately but as a mixture, there is a greater variance in the temperatures for each one.
Fortunately each of the substances will tend to dominate around its boiling point temperature, thus we can determine which alcohol is dominating and being produced at that point.
Temperature readings of a distillation are taken in the vapour chamber area of the still, usually the lid where vapours gather before proceeding to the refinig lentil or condensing recipient.
By tracking the temperature of the vapour you will know when you are collecting the desired ethanol and how the purity of the run is proceeding. Temperature reading must be between 78º to 82 ºC or other chemical substances will be obtained.
If you are not obtaining the desired temperature, you will have to increase or decrease the heat source accordingly. This is the first stage of obtaining the desired alcohol. Once the distillate starts to exit the condensing recipient, basic distillation rules must be respected to define cutting off points.
You may use a copper parrot spout and alcoholometer to aid you in this task.
- 1 Why it is futile to try and boil your Mash at a specific Temperature
- 2 Temperature conditions for distillation of moonshine. General information about the freezing point and boiling point of alcohols. Household and industrial use
- 3 Distillation
Why it is futile to try and boil your Mash at a specific Temperature
First published on Distillique's website in 2015 by GM Bosman
In the distilling industry, there are many myths which have persisted over many years. This is especially true amongst Home Distillers or Cultural Distillers.
One of these myths (that lead to many an argument during some of our training sessions) is the belief that you should boil your mash at a certain temperature to “boil off” the alcohol before the water starts boiling.
Almost all Home and Cultural Distillers, and especially “Web Educated” Distillers believe this. “You distill at THIS temperature”. But nobody can explain why they all have a different temperature!
Now we all know that alcohol boils at 78.3˚C and water at 100˚C (at standard atmospheric pressure of 101.325 kPa) – and this fact has lead to the growth of this distilling myth: “That you should boil your mash at a specific temperature to get the alcohol first”.
- We have been asked numerous times at which temperature we boil our mashes to get “good alcohol”.
- The answer to this is not easy without explaining some physics and thermodynamic principles first.
- Raoult was the first to discover in 1882 that different liquids, when mixed, will NOT boil at their individual boiling temperatures, but at a different temperature, depending on the amount of each liquid present in the a solution.
- This simply means that, according to Raoult, a 50/50 solution of two liquids, will boil at a temperature that is the average of the two liquids temperature.
I.e. Water boiling at 100 degrees and ethanol at 78 degrees. A solution of 500ml water and 500ml ethanol will therefore boil at 89 degrees – halfway between.
Should the concentration of ethanol be greater (lets say 750ml) vs water (250ml), then the boiling temperature of the solution will be closer to the boiling temperature of the greater component, in other words lower.
Should the reverse be true, and the concentration of water (at 750ml) is greater than the amount of ethanol (250ml) then the boiling temperature of the solution will be closer to the boiling temperature of water, in other words, higher.
Obviously in a Fermentation we are not just dealing with Ethanol and Water though – we have Methanol, Acetone, Hydrogen Sulfide, Fusil Oils, Acids, Esters, etc. Each of these components, liquids and dissolved solids will have an impact on the boiling temperature of the fermentation. For sake of argument (and to avoid complicating matters) we will however just focus on Ethanol and Water.
Now, this fact of the concentration of different liquids and their individual boiling points impacting the boiling point of a solution is known in physics as “Raoult’s law” and is valid for “ideal solutions”, normally portrayed as a nice straight line on a Graph.
Unfortunately a solution of water and ethanol is however seen as a “non-ideal” solution, and therefore the results are a bit different.
Instead of a nice straight line, here we use the proven thermodynamic and physics concept of “phase diagrams”.
A phase diagram is a graph indicating at which temperature a solution will start boiling (or condenses) for the various percentages of liquids in the solution.
In the phase diagram, everything above the pink line is vapour (or gas), below the blue line everything is liquid, and between the blue and red line, a mixture of gas and vapour exists. The blue line is also called the boiling, or bubble line, while the red line is also called the dew point, or condensation line.
This graph also explains why we cannot distil to purer levels than 95.5% alcohol (using normal distillation methods). This is called the alcohol/water azeotrope.
From the graph, we can see that, for example, a mash with 15% alcohol, will boil at a temperature of 90.5 ˚C. (at standard atmospheric pressure). No matter how big or hot a flame (energy input) we put under our kettle, the mash WILL boil at this temperature and this temperature alone.
As we continue to put heat / energy into the kettle, the temperature of the vapour directly above our mash will not become hotter or colder than the boiling temperature. The energy will however be used to turn more liquid in the boiling vapour, into vapour (the area between the red and blue lines) until all the liquid is vaporised (at the red line).
As we can see from the solid orange line (of the 15% mash example) is that it crosses the red line and that, if we look at the composition of the vapour at that point, the vapour now contains MORE alcohol than the 15% in the mash. In other words, the mash boils at the 90.5C temperature and the resulting vapour contains a richer alcohol content.
If we now condense this alcohol rich vapour, it will condense into a liquid which is higher in alcohol content (the basic mechanism how distillation works).
BUT … because we extract the alcohol richer vapour, the alcohol percentage in our mash reduces. As the percentage of alcohol in our mash reduces, so the boiling temperature of our mash rises.
The conclusions we can draw from the alcohol/water phase diagram is as follows:
1. The boiling temperature of a mash depends on the percentage of alcohol (and other components) in the mash. We therefore cannot decide at which temperature we want to boil our mash, as we do not know EXACTLY which components formed during fermentation and in which concentrations.
2. As we distil, the percentage of alcohol in our mash slowly reduces, and the boiling temperature slowly rises.
3. If there is no more alcohol left in the mash, the boiling point will reach 100 C – that of the last remaining water in the mash (just before our kettle will boil dry).
Off course the phase diagram can also be used in “reverse”. For example: If we collect our alcohol from a pot still at 55% alcohol, we can use the graph to see how much alcohol is left in the mash. If for example, our distillate reaches 20% alcohol, we would see on the graph that the mash only contains about 2% alcohol.
The above is true ONLY for a proper pot still with no internal reflux.
In a later article we will discuss internal reflux in stills and then understand why different still designs give different results when distilling.
Attend one of our distilling courses and you will learn how the phase diagram is used and how to determine your own still’s natural internal reflux ratio…and off-course how to use this to make really good spirits! …and why some stills have thermometers in the boiler (kettle) and another one close to the top.
Temperature conditions for distillation of moonshine. General information about the freezing point and boiling point of alcohols. Household and industrial use
Column control comes down to a simple rule: you cannot select a fraction at a rate exceeding the rate at which it enters the column. Methods for determining the moment when this speed begins to be exceeded are various. The main thing is to understand as early as possible that the balance has been violated, and by reducing the rate of selection, restore it.
In the simplest version, control is possible using two thermometers:
- vat, showing the moment of boiling of raw alcohol in a cube, transition to the selection of “tails” and the end of the process;
- a thermometer located 20 cm from the bottom of the nozzle. In this zone, all transient processes are completed, the temperature is more or less stable and reflects the processes occurring in the column with the maximum lead in relation to the withdrawal zone. An increase in temperature even by 0.1 degrees indicates that too much alcohol is taken away – more than it enters the column, therefore, it is necessary to reduce the sampling rate. If the withdrawal is not reduced, the separation into fractions in the column will deteriorate, and impurities from the equilibrium position established for them will move up the column, closer to the withdrawal.
During rectification due to forced reflux and precise control of the reflux ratio, the most volatile fractions are obtained at the outlet, which can be taken sequentially. In addition, competent control of the column allows stopping the movement of unnecessary impurities into the extraction zone in it, accumulating them up to a certain time in the column, or even returning them to the cube.
The distillation column is not so much an accurate, but rather a powerful tool for the total purification of alcohol from impurities.
It is hardly applicable for obtaining noble distillates, since it requires special technologies and methods.
The grouping of impurities by volatility and the high concentration of alcohol in the column create azeotropes from them indiscriminately into necessary and unnecessary; it will no longer be possible to separate them.
When obtaining noble distillates, the goal is not to completely purify alcohol from all impurities, but to reduce their concentrations in a balanced manner with partial removal of some of the most unnecessary ones. A partial condensation apparatus is required, working on which the distiller divides the distillate into parts, and then assembles a masterpiece from this mosaic.
With all the external difference, the most important properties of impurities – their volatility and the associated rectification coefficients – lie at the heart of the management of distillation and rectification.
By controlling the reflux ratio in a very limited (during distillation) or, conversely, very wide (during rectification) ranges, you can get a very different product: from a distillate balanced in impurities to pure alcohol.
The main thing is to understand the principles of management and use the right tool in each case.
P.S. On 03/30/2018, the article was supplemented and significantly revised, comments before this date have lost their relevance.
A bit of theory
Alcohol has a density different from water, and, therefore, its evaporation temperature will be different… This knowledge is used most widely when distilling mash.
Fermented compote or jam is distilled, getting moonshine at the exit. This is not the magic of turning water into wine, this is a common physical phenomenon.
When the mash is heated, the most volatile alcohols, which are the most poisonous for the body, begin to evaporate first.
The next to evaporate is ethyl alcohol, followed by heavy alcohols, the use of which also often leads to death from low doses.
Before you start driving, you need to know:
- Boiling points of alcohols. Each faction has its own degree.
- The cleaner the final product is, the better the distillation is.
- The main guarantee of the quality of the final product is the quality of the initial wash.
Relying on this knowledge, the distillation process is based. Thus, a distillate of alcohol is obtained from sugar, berry, grain, fruit and any other mash. First you need to figure out at what temperature the moonshine is driven?
Boiling points of alcohols
As soon as the mash is heated to a certain temperature , the most volatile parts begin to evaporate first… Methanol, acetaldehyde and other especially dangerous poisons are evaporated first. This happens already at a boiling point of 64–67 degrees.
Second phase – ethyl alcohol is separated – the heating fire is reduced to a minimum. Thus, the temperature is maintained at about 62-64 degrees. It is this temperature that must be maintained throughout the entire distillation. However, the distillation temperature of moonshine in the container gradually rises as the alcohol evaporates.
When the temperature rises to 85 degrees, the third stage begins… Now all possible ethyl alcohol has already separated, and fusel oils are evaporated behind it. These are also poisonous substances that are not consumed for drinking purposes.
The temperature should not be allowed to rise to 95 degrees and above. Such overheating will lead to the release of the mash into the cooling element of the moonshine still. This will noticeably impair the quality of the final drink, its color and taste.
The most popular property of liquids to evaporate at different temperatures is in the art of home brewing… There it opens in all its glory. Its application is to evaporate all the alcohols unnecessary in the final product and obtain pure alcohol at the exit.
That's just the art of home brewing and the art that in this area they learned to do many very interesting things.
The use of the art of moonshine is by no means limited to muddy, smelly moonshine. At home, some enthusiastic people have learned to drive real works.
But, starting from the basics, what are the main stages of distillation? And how to properly distill moonshine from home brew?
Some of the most useful devices for home brewing simple meters will become:
- Home brewing thermometer.
- Alcohol meter.
At the first stage the process of evaporation of the most volatile fractions takes place, including dangerous poisons: acetone, methanol. The so-called head cut is removed. At this stage, the separation of methyl alcohol occurs. The boiling point of methanol is 64.7 degrees Celsius.
Initially, the container with the mash is set on maximum fire, and it gradually heats up to this temperature.
The fact that the distillation of mash has begun can be judged by the smell that stands out brightly when the first squeeze appears.
“Pervak” (as the people call the squeeze from the first distillation tap), has a pungent, not too pleasant smell, the reason for it is methanol and its boiling.
For some very long time, it was “pervak” that was considered the best moonshine. They get drunk faster from it, and for this quality it has become so popular for consumption. However, the head cut intoxicates faster, not because it has a higher degree, but because contains poisonous substances.
We have discussed what is involved in the fermentation of sugar to alcohol and by
this time many of you have direct experience of this process. The fermentation of
alcoholic beverages is a technology that dates back to the stone age.
separation of the alcohol from the water, on the other hand, is a
relatively recent development. The Chinese were distilling rice beer as
early as 800 BC. But the separation of ethyl alcohol as a substance was not
achieved in Europe until the 12th century AD.
At that time it was regarded
by the alchemists as a “fifth essense” or “quintessence,” a higher form of water
which was capable of dissolving many medicines which were not soluble in ordinary water.
The use of alcohol for medicinal purposes is reflected in another common name for
alcohol: aqua vitae (water of life), a name which survives as the name of a modern
The principle problem of the preparation of alcohol is that yeasts are unable
to ferment a liquid which is more than about 18% alcohol. It is useful to view
alcohol as a waste product from the yeast's point of view.
Beyond about 18%
they simply cannot live in their own “urine.” We start, then, with a liquid
which is between 5% and 15% alcohol and our primary task is to separate the
alcohol from the water and other materials.
There are two common methods for doing
this: freezing and boiling.
We have already discussed the melting and freezing of solutions when we discussed
the difference between quartz and glass.
Recall that a pure substance melts and
freezes at a single temperature, that is, the melting point equals
the freezing point.
By contrast, a solution melts over a range
of temperatures rather than at a single point. Let us recall the behavior of water
as it freezes.
Pure water freezes at 0 C. Pure ice melts at 0 C. If I start with water at room
temperature and cool it, the temperature will drop. From 25 C (room temperature)
to 20 C, 10 C, 5 C, 0 C. But at 0 C something peculiar happens, ice crystals form.
By the time that half the water has turned to ice, the temperature is still 0 C.
Only after all the water is frozen will the temperature fall to -1 C, -5 C, …
Similarly if I start with ice at -10 C and warm it, it will warm to -5 C, -1 C,
0 C but then the ice starts to melt.
The temperature will stay at 0 C until the
last bit of ice is melted and then will start to rise again.