Calculates continuously operated columns and displays them graphically.
The individual plates of a continuously operated column are shown.
This column can be heated by injecting water steam from below and / or by heating from below, a "reboiler".
Columns heated by water vapor injection are mainly used in the bourbon industry to produce low wines. There they are called "stripping columns".
Water has a much higher enthalpy of vaporization than alcohol. This means that water steam transports much more energy than is required to vaporize the same amount of alcohol. Of course, you don't get this large amount of energy for free, you have to invest it first when producing the steam. However, this high enthalpy of vaporization has the great advantage that less water steam is needed in the column and therefore the alcohol content is not diluted as much by the water injection, so that a high alcohol strength is achieved in the distillate without having to use energy-demanding reflux. An additional advantage of water steam injection is that this water is of course absolutely clean. Unlike the liquid in the reboiler.
The stripping columns are operated without reflux. The feed is normally placed on the top plate of these columns. However, this does not necessarily mean that, based on the alcohol strength of the feed, only one maximum theoretical plate is reached. This is because the alcohol strength in the plate into which the feed is introduced is not normally the same as the alcohol strength of the feed. Both a lower and a higher alcohol strength can be established there. However, more than a theoretical base is not necessary for a bourbon stripping column, as the alcohol strength must not be too high if the product is to be called bourbon. The plates of the bourbon columns only have the function of ensuring that there is almost no alcohol left at the bottom, where the so called "waste" flows out. This means that the feed flowing downwards is leached out as completely as possible. This is sufficient at the preset of the computer. If you add more plates at the bottom in this case, this only increases the heat loss to the environment. As a result, less vapor reaches the top, you get slightly less distillate, but with a slightly higher alcohol strength, because the heat loss means reflux and therefore rectification. From an economic point of view, this is probably more of a disadvantage in this case.
Most continuous columns are not thermally insulated. Perhaps this is because it makes very little difference. The heat loss to the environment depends very much on the time it takes to distil a certain amount of feed. And these columns have a very high throughput. So even if you lose a significant amount of energy per time, you lose very little per liter of alcohol collected - and that's what matters economically.
The calculation of the heat loss is based on the same data that we measured for our calculator Potstill / Thumper and refers to an ambient temperature of 20 °C.
The need for insulation is completely different with a batch reflux still, i.e. what many people here in the forum use to produce neutral alcohol or single run spirits, because the liquid spends a multiple of the time in the still. This is why the energy loss per quantity of alcohol is also multiple times greater.
The input of the column height and the column diameter is only necessary in the calculator to calculate the vapor speed and the heat loss. A large column naturally loses more heat to the environment than a small one. If 100 % column insulation is set, there is no heat loss and therefore the height and diameter of the column have no effect on this.
The calculator therefore assumes that the diameter and height of the individual plates are chosen so that the still functions efficiently. The calculated vapor velocity can be an indication of this. This is because a vapor speed that is too high has a negative effect on efficiency. The vapor velocity on the lowest plate is calculated. In other words, the speed of the steam introduced (and / or the steam from the reboiler) in relation to the column diameter. This is always the highest vapor velocity in the column. Further up, the velocity is lower, in principle because alcohol vapor has slightly less volume "per watt" than water steam, and depending on the way up due to heat radiation, cold feed and reflux.
With a stripping column for viscous mashes, however, you normally have to choose such a large diameter anyway due to the risk of clogging that the vapor velocity is very low.
The plate efficiency can be set between 50 and 100 %. In our calculation, an efficiency of 50 % means that for each plate, half of the vapor flowing into the plate from below passes through the liquid in the plate unchanged. This incomplete interaction of vapor and liquid leads to less alcohol concentrating in the column.
If you have a column with packing, you should normally set the efficiency slider to 100 %, as a packing height corresponding to a real plate in terms of separation capacity means a real plate with 100 % efficiency.
If reflux is set, a distinction must be made between a complete condenser, which condenses all the vapor arriving at the top and returns part of it to the column, and a partial condenser, which condenses only the part that is returned. Partial condensation results in more or less efficient additional alcohol enrichment. "100 % partial condensation efficiency" means that, depending on the % reflux, maximal one additional theoretical plate can be generated by partial condensation. Only a CM has a partial condenser. Full condensation is used in all other systems, i.e. LM and VM or similar. Further information: Partial Condensation
Generally, however, columns heated with steam injection are operated without reflux. This is because reflux means that more steam has to be introduced for the same amount of distillate. And more steam means that the alcohol is diluted more with water, which negates the alcohol enrichment caused by the reflux. An example of a column with a feed in the middle, so different from a classic stripping column with the feed at the top, but more illustrative of what can and cannot be achieved with reflux here:
On the left, without reflux, you get 33 ml distillate with 44.2 %abv with the steam from 1900 watts.
On the right, with 50 % reflux and the amount of steam increased so that you get about the same amount of distillate, you get 34 ml/min with 44.4 %abv.
This is only marginally different.
However, you now need 2800 watts, i.e. 47 % more energy than without reflux.
This means that it is not economically possible to produce neutral alcohol or vodka with such a still. For this you need a system that feeds less water into the column. In other words, conventional heating from below, in addition to or instead of steam injection. The reflux from the lowest plate runs into the reboiler, a heated boiler, where part of it evaporates again and the other part is disposed of as waste, so that the level in the boiler remains constant. (The reboiler is not shown in the diagram, but the vapor it produces is added to the water steam introduced at the bottom). In this way you get continuous energy into the column without adding more water. However, this does not work well with a mash containing a lot of solids. The solids would accumulate in the boiler and eventually scorch on the heating system. This is why neutral alcohol or vodka is normally produced with more than one column:
The rectifier usually generates the reflux using the wash as a coolant, whereby the wash enters the analyzer heated. A low feed temperature means less vapor development above the feed. And that means less distillate with a slightly higher alcohol strength. This can be counteracted with a little more steam from below. Preheating the feed therefore does not generally improve the system, but is one steps towards greater energy efficiency.
A reflux cooling water consumption is also calculated. This is only intended as a guide. A more precise calculation would require a great deal of information, which you probably do not even know. The calculation assumes a cooling water temperature of 20 °C and that the cooling water is heated exactly to reflux temperature, which means that the reflux cooler provides the best possible performance. At least with partial condensation, such a cooling water efficiency can be approximately achieved in practice. In systems with full condensation, on the other hand, a surplus of cooling water must always be used. The calculation does not take this into account.
The calculator does not take into account eventual cooling of the reflux below its boiling point. But calculation results with our Column Simulator show, that this has no major impact apart from a small loss of energy.
The calculation is not carried out according to McCabe-Thiele in this calculator. The same boiling point diagram data is used as in our other calculators, but instead of using the simple rules of the McCabe-Thiele method, the values are calculated according to the following rules:
A calculation that follows these two rules can only be carried out using a simulation. The calculator first fills all plates below the feed with feed, then adds the water steam from below and calculates in very small steps how the values in the column slowly change. When not much more changes, the result is displayed.
This type of calculation takes some time. In some cases, it can take a few seconds for a result to be displayed on old computers. Especially if the waste has a low alcohol strength and the distillate has a high alcohol strength. For this reason and because high accuracy is not so important there, this type of calculation is not implemented in our Potstill and Thumper Simulator, but instead it is still calculated according to McCabe-Thiele.
The calculated theoretical bottoms here refer to the distance between the alcohol strengths of the feed and the distillate.
The colors of the column refer to the alcohol strength. The color code is: black for 0 %abv, red for 50 %abv, yellow for 75 %abv, green for 90 %abv and blue for 100 %abv.
The feed can be switched between ml/min and g/min. This also determines whether ml/min or g/min is displayed on the left of the column. For vapor, ml/min means the volume if the vapor had condensed and cooled down to 20 °C. Not the much larger vaporous volume. However, its displayed temperature naturally refers to the actual temperature of the vapor in the column.
About the calculated energy balance:
Of course, it is important to know the energy required for the water steam. This is the sum of the energy required to heat the water to the boiling point (based on water at 20 °C) and the far greater evaporation energy. The negative watt values further down indicate the energy that must be dissipated or can be recovered, i.e. either dissipated in cooling water or used with a heat exchanger to preheat the water steam water or the feed. At the bottom, the loss to the environment is shown in absolute watts and in brackets as a percentage of the energy used.
Atmospheric pressures between 75 and 10000 hPa can be calculated. The consideration of the atmospheric pressure has a substantial influence on the result. If nothing is entered, the calculator assumes the local atmospheric pressure 1013.25 hPa.
Information about our boiling point data and about the influence of atmospheric pressure
This column can be heated by injecting water steam from below and / or by heating from below, a "reboiler".
Columns heated by water vapor injection are mainly used in the bourbon industry to produce low wines. There they are called "stripping columns".
Water has a much higher enthalpy of vaporization than alcohol. This means that water steam transports much more energy than is required to vaporize the same amount of alcohol. Of course, you don't get this large amount of energy for free, you have to invest it first when producing the steam. However, this high enthalpy of vaporization has the great advantage that less water steam is needed in the column and therefore the alcohol content is not diluted as much by the water injection, so that a high alcohol strength is achieved in the distillate without having to use energy-demanding reflux. An additional advantage of water steam injection is that this water is of course absolutely clean. Unlike the liquid in the reboiler.
The stripping columns are operated without reflux. The feed is normally placed on the top plate of these columns. However, this does not necessarily mean that, based on the alcohol strength of the feed, only one maximum theoretical plate is reached. This is because the alcohol strength in the plate into which the feed is introduced is not normally the same as the alcohol strength of the feed. Both a lower and a higher alcohol strength can be established there. However, more than a theoretical base is not necessary for a bourbon stripping column, as the alcohol strength must not be too high if the product is to be called bourbon. The plates of the bourbon columns only have the function of ensuring that there is almost no alcohol left at the bottom, where the so called "waste" flows out. This means that the feed flowing downwards is leached out as completely as possible. This is sufficient at the preset of the computer. If you add more plates at the bottom in this case, this only increases the heat loss to the environment. As a result, less vapor reaches the top, you get slightly less distillate, but with a slightly higher alcohol strength, because the heat loss means reflux and therefore rectification. From an economic point of view, this is probably more of a disadvantage in this case.
Most continuous columns are not thermally insulated. Perhaps this is because it makes very little difference. The heat loss to the environment depends very much on the time it takes to distil a certain amount of feed. And these columns have a very high throughput. So even if you lose a significant amount of energy per time, you lose very little per liter of alcohol collected - and that's what matters economically.
The calculation of the heat loss is based on the same data that we measured for our calculator Potstill / Thumper and refers to an ambient temperature of 20 °C.
The need for insulation is completely different with a batch reflux still, i.e. what many people here in the forum use to produce neutral alcohol or single run spirits, because the liquid spends a multiple of the time in the still. This is why the energy loss per quantity of alcohol is also multiple times greater.
The input of the column height and the column diameter is only necessary in the calculator to calculate the vapor speed and the heat loss. A large column naturally loses more heat to the environment than a small one. If 100 % column insulation is set, there is no heat loss and therefore the height and diameter of the column have no effect on this.
The calculator therefore assumes that the diameter and height of the individual plates are chosen so that the still functions efficiently. The calculated vapor velocity can be an indication of this. This is because a vapor speed that is too high has a negative effect on efficiency. The vapor velocity on the lowest plate is calculated. In other words, the speed of the steam introduced (and / or the steam from the reboiler) in relation to the column diameter. This is always the highest vapor velocity in the column. Further up, the velocity is lower, in principle because alcohol vapor has slightly less volume "per watt" than water steam, and depending on the way up due to heat radiation, cold feed and reflux.
With a stripping column for viscous mashes, however, you normally have to choose such a large diameter anyway due to the risk of clogging that the vapor velocity is very low.
The plate efficiency can be set between 50 and 100 %. In our calculation, an efficiency of 50 % means that for each plate, half of the vapor flowing into the plate from below passes through the liquid in the plate unchanged. This incomplete interaction of vapor and liquid leads to less alcohol concentrating in the column.
If you have a column with packing, you should normally set the efficiency slider to 100 %, as a packing height corresponding to a real plate in terms of separation capacity means a real plate with 100 % efficiency.
If reflux is set, a distinction must be made between a complete condenser, which condenses all the vapor arriving at the top and returns part of it to the column, and a partial condenser, which condenses only the part that is returned. Partial condensation results in more or less efficient additional alcohol enrichment. "100 % partial condensation efficiency" means that, depending on the % reflux, maximal one additional theoretical plate can be generated by partial condensation. Only a CM has a partial condenser. Full condensation is used in all other systems, i.e. LM and VM or similar. Further information: Partial Condensation
Generally, however, columns heated with steam injection are operated without reflux. This is because reflux means that more steam has to be introduced for the same amount of distillate. And more steam means that the alcohol is diluted more with water, which negates the alcohol enrichment caused by the reflux. An example of a column with a feed in the middle, so different from a classic stripping column with the feed at the top, but more illustrative of what can and cannot be achieved with reflux here:
This means that it is not economically possible to produce neutral alcohol or vodka with such a still. For this you need a system that feeds less water into the column. In other words, conventional heating from below, in addition to or instead of steam injection. The reflux from the lowest plate runs into the reboiler, a heated boiler, where part of it evaporates again and the other part is disposed of as waste, so that the level in the boiler remains constant. (The reboiler is not shown in the diagram, but the vapor it produces is added to the water steam introduced at the bottom). In this way you get continuous energy into the column without adding more water. However, this does not work well with a mash containing a lot of solids. The solids would accumulate in the boiler and eventually scorch on the heating system. This is why neutral alcohol or vodka is normally produced with more than one column:
- The first without reflux, only with steam injection, which is primarily intended to remove the solids and get as much alcohol as possible into the distillate. This column is sometimes called an "analyzer". The feed is placed on the top or one of the top plates. This corresponds to a stripping column for bourbon.
- And a second column with a reboiler and reflux condenser, often called a "rectifier".
In this column, the feed, i.e. the distillate from the analyzer, is fed in almost at the bottom.
As there are hardly any plates underneath, the alcohol yield is very poor.
However, the alcohol-rich waste is returned to the analyzer, usually one or a few plates below the feed for the mash.
And the analyzer has a very high alcohol yield.
This means that no alcohol is lost.
Here are a few simulations of a rectifier:On the left is a normal version of a rectifier. You can see that you get a strong distillate due to the reflux and the heating without water steam injection, but a completely unacceptable alcohol yield. But perhaps this will improve if there are a few more plates below the feed?
On the right five more plates are now simply added at the bottom. Unfortunately, it doesn't help. The amount of distillate, its alcohol strength and the alcohol yield remain almost the same.
On the left, additional water steam is introduced instead of the additional plates, but the % reflux is kept the same. And that looks much better. The %abv at the top drops only slightly, but the alcohol yield is now very good. And the kWh per liter of alcohol collected has even gone down.
On the right, with both steam and additional plates at the bottom, everything is now under control. Both strong distillate and high yield.
However, the system is now very fragile. The exact % reflux in particular is very critical:
On the left, with 1 % more reflux, the alcohol yield is significantly lower. And on the right, with 1 % less reflux, the distillate is significantly less strong.
In any case, it is common practice in the production of neutral alcohol or vodka to separate the tasks: One column for alcohol yield and one for concentration. The difficult control system may play a part in this.
These two columns can be decoupled by intermediate tanks. This means that the low wines from the analyzer are not fed directly into the rectifier and the waste from the rectifier is not fed directly into the analyzer. This ensures that both columns always receive the same feed, which makes them run more stably. - There may also be other columns with special tasks.
For example, a "demethylizer":
Here, the already highly rectified alcohol is fed into a column at the bottom, evaporated with a reboiler and a fraction with a high methanol content is separated off at the top with reflux. Almost the same alcohol strength then comes out at the bottom as waste, only with much less methanol and perhaps other congeners. So in this case, the waste is the product and the distillate is the waste.
The high alcohol strength in the feed is necessary because the volatility of methanol is highest relative to that of ethanol at high alcohol strengths. More about this here: Congeners Information
The rectifier usually generates the reflux using the wash as a coolant, whereby the wash enters the analyzer heated. A low feed temperature means less vapor development above the feed. And that means less distillate with a slightly higher alcohol strength. This can be counteracted with a little more steam from below. Preheating the feed therefore does not generally improve the system, but is one steps towards greater energy efficiency.
A reflux cooling water consumption is also calculated. This is only intended as a guide. A more precise calculation would require a great deal of information, which you probably do not even know. The calculation assumes a cooling water temperature of 20 °C and that the cooling water is heated exactly to reflux temperature, which means that the reflux cooler provides the best possible performance. At least with partial condensation, such a cooling water efficiency can be approximately achieved in practice. In systems with full condensation, on the other hand, a surplus of cooling water must always be used. The calculation does not take this into account.
The calculator does not take into account eventual cooling of the reflux below its boiling point. But calculation results with our Column Simulator show, that this has no major impact apart from a small loss of energy.
The calculation is not carried out according to McCabe-Thiele in this calculator. The same boiling point diagram data is used as in our other calculators, but instead of using the simple rules of the McCabe-Thiele method, the values are calculated according to the following rules:
- What leaves each plate downwards as reflux and upwards as vapor is exactly the same as what is added to each plate from above as reflux and from below as vapor.
- What is taken from the top as distillate is equal to the difference between the vapor produced by the boiler and what flows back into the boiler as reflux.
A calculation that follows these two rules can only be carried out using a simulation. The calculator first fills all plates below the feed with feed, then adds the water steam from below and calculates in very small steps how the values in the column slowly change. When not much more changes, the result is displayed.
This type of calculation takes some time. In some cases, it can take a few seconds for a result to be displayed on old computers. Especially if the waste has a low alcohol strength and the distillate has a high alcohol strength. For this reason and because high accuracy is not so important there, this type of calculation is not implemented in our Potstill and Thumper Simulator, but instead it is still calculated according to McCabe-Thiele.
The calculated theoretical bottoms here refer to the distance between the alcohol strengths of the feed and the distillate.
The colors of the column refer to the alcohol strength. The color code is: black for 0 %abv, red for 50 %abv, yellow for 75 %abv, green for 90 %abv and blue for 100 %abv.
The feed can be switched between ml/min and g/min. This also determines whether ml/min or g/min is displayed on the left of the column. For vapor, ml/min means the volume if the vapor had condensed and cooled down to 20 °C. Not the much larger vaporous volume. However, its displayed temperature naturally refers to the actual temperature of the vapor in the column.
About the calculated energy balance:
Of course, it is important to know the energy required for the water steam. This is the sum of the energy required to heat the water to the boiling point (based on water at 20 °C) and the far greater evaporation energy. The negative watt values further down indicate the energy that must be dissipated or can be recovered, i.e. either dissipated in cooling water or used with a heat exchanger to preheat the water steam water or the feed. At the bottom, the loss to the environment is shown in absolute watts and in brackets as a percentage of the energy used.
Atmospheric pressures between 75 and 10000 hPa can be calculated. The consideration of the atmospheric pressure has a substantial influence on the result. If nothing is entered, the calculator assumes the local atmospheric pressure 1013.25 hPa.
Information about our boiling point data and about the influence of atmospheric pressure