Temperature & ABV Relationship Charts

[drinktofabfabtodrink]

These charts would be for a batch set up, right? Do you know how these charts would look for a continuous distillation set up?

[smokindave]

Great chart. I have found it really helpful as a newbie. I can check my boka column thermo vs. my parrot proof and just watch the trend in the distillate %. It is a nice reference for keeping tabs on how things are progressing through a run.

[rad14701]

These charts would be for a batch set up, right? Do you know how these charts would look for a continuous distillation set up?

These charts show the relationship of alcohol by temperature so the fact that a continuous distillation process has no cuts makes no difference... You would only be using the red line which indicates the %ABV of the distillate vapor produced and would back-trace to what the incoming wash %ABV is... Both should remain steady...

[greenthumb]

Finding this saves me asking the questions I had, very handy thanks rad

[scarr]

So, I hope I don't sound like a simpleton, ideally if my vapor temp in a reflux still should be ran at the lowest temp possible to end up with the highest abv%.
Did i get the concept correct?

[BIGBIRD123]

Okay i have been studying these charts and think i understand. But the premise of these is based on a 10% wash. How do the charts differ if a 12%, 14%, 18%? It seems like i get more hearts from a reflux run if the wash is 18% then 10% but my temp seems to creep up a bit in to the 80 degree range versus the 78.2 range. I want to try and figure some maximums and some efficiencies.

Are you running a pot still or a reflux column...??? A pot still will always creep up from the time output starts until you shut down... A reflux column will only creep up as the alcohol in the wash depletes and not enough reflux can be maintained to keep the output at purity, either due to inefficiency of the still, operational techniques, or there's simply not enough alcohol left in the wash...

The charts are not based on 10%, they work with ANY percentage... There are several ways to use the charts... If you know the %ABV of your wash you can determine the boiling temperature as well as the vapor temperature... Or at a given vapor temperature you can determine the wash temperature and the %ABV of the wash remaining in the wash...

Let's say that for some reason you are running a thermometer in the vapor path of a pot still... You heat an unknown %ABV wash until it starts producing vapor and the temperature begins to rise rapidly... At some point the temperature will stabilize, but only for a few minutes as the temperature will continue to rise as alcohol is removed... Let's assume that this temperature initially stabilizes at 196F... By finding where the 196F line meets the blue line and running down to the %ABV at the bottom you will see that the wash contains 14% alcohol... Now continue over to the red line and follow down from there and you will see that the %ABV of the vapor, as well as the spirits collected, will be ~61% ABV... Or you can calculate that a 6% ABV wash will not reach a stabilized vapor temperature until 204F and will be producing 40% ABV spirits at that moment in time...

For a reflux column you can determine the %ABV of your spirits by simply running down from where the temperature line meets the red line... A vapor temperature of 174F is ~90% ABV or 180 proof... 180F is ~80% ABV or 160 proof... However, for a reflux column you cannot do a reverse lookup to determine the %ABV of the wash based on column vapor temperature... You would need to measure the vapor temperature in the boiler, or the wash temperature, in order to determine how much alcohol is left in the boiler, taking into account the amount of liquid spirits already removed... This measurement isn't of all that much help when running a reflux column but if you consistently run the same wash recipe it might help indicate when you are getting close to the tails...

The charts are very versatile once you become familiar with them, but they should only be used as a reference of approximation... They are not to be relied on as being 100% accurate due to the number of variables involved in the distillation process...

Rad,
This is by far one of the best explanations of some of the more delicate parts of running a still. I did not understand what another member was talking about with remaining abv, vapor path, etc but NOW I am understanding. I was trying to run my still up and holding the temp at 172F but had to adjust the heat back and forth to do so...I now know that that is imposssible and probably why my run just stopped making anything. the temp was rising because it was supposed to and I was trying to keep if from doing just that...Thanks for you extreme knowledge level and ability to get the point across even to us Ole' Texas Boys...

[Jacksonbrown]

Were the values to plot the charts in the OP calculated or just entered from the table in the parent site?

I’m hoping someone has an Excel spread sheet with the full equation in it.

If so there should be a value for pressure in it which I’d like to change to reference a cell containing an entered altitude.


I’m assuming the temps in the chart are only correct at mean sea level pressure (MSLP) but I’m in the mountains so my water doesn't boil at 100°C and product comes off at 77°C with a little bit of refluxing.

Has anyone done something like that, to correct for altitude?

[Jacksonbrown]

Guess not.

Still keen if anyone's interested or let me know if I'm off track.

[Bill-a-newbie]

I may have missed it, but the temp. on the left side of the chart.......Where is that measured at? In the pot, at the top of the column? Is that the temp of the mash?
Thanks,
Bill

[Prairiepiss]

I may have missed it, but the temp. on the left side of the chart.......Where is that measured at? In the pot, at the top of the column? Is that the temp of the mash?
Thanks,
Bill

For the red line it in the vapor path.
For the blue line its in the boiler liquid.

[Bill-a-newbie]

Thanks Prairiepiss, Is there an EASY way to get the temp of the boiler that does not have a thermometer?

[Prairiepiss]

Not without a thermometer of some sort.

[Bill-a-newbie]

Is there any way to tell the temp of the boiler by the temp. in the top of the column?
Has anyone ever tried one of those stick on thermometers on the outside of the boiler?

[Prairiepiss]

Most don't go high enough.

[Jacksonbrown]

Not with only one temp at the top of the column

If you had your column modeled exactly I suppose it is would be mathematically possible to work backwards but it would also require the reflux temps and the more HETP the less accurate IMO.

I haven't seen the stick on thermometer that go that high, do they exist? They're usually designed for aquariums.
The light gun thermometers might be what your after.

[Bill-a-newbie]

The light gun thermometers might be what your after.

I have one we used for racing to check the temp. of the tires. I wonder how close that would read the boiler temp from the outside of the tank?

[Jacksonbrown]

About the same as a stick on one I guess.

[rad14701]

Were the values to plot the charts in the OP calculated or just entered from the table in the parent site?

Not sure how I missed this until now... Been a crazy few months around here... All numbers were calculated and the chart made using Excel... The one thing not possible, at least I haven't figured out how, is to calculate the %ABV based on a given temperature... I haven't played with the concept in a few years, however...

[Jacksonbrown]

This is very close but falls down above 99.8°C

%=1+0.00474794075261437*T^2/(T^2-76.6991315532679^2)+0.166271372469937*T^2/(T^2-107.752485459244^2)

If Maritimer comes back we might be able to get it exactly the same as the base equations you used originally but I believe these are still just approximations.
Whether those equations were gleaned for experimental data or a much more complicated equation would be of interest.
Most on here wouldn't be stillen' on the beach so an elevation input would be of real use I think.

What I was originally referring to was to use something like this-
http://en.wikipedia.org/wiki/Boiling_po ... d_pressure

With a touch of this-
http://en.wikipedia.org/wiki/Vapor_pres ... e_equation

Maybe with a bit of this in too
http://en.wikipedia.org/wiki/Boiling-po ... centration

I don't even know if it's possible (especially for a multi component solution) but if someone did it, I'd use it.

A model that actually calculated exactly what was going on, rather than just an approximation of it.

[rad14701]

If you haven't checked, the formulas posted in the text don't match the actual formulas used in all of the Javascript calculators... It's always a good idea to check the actual page source rather than merely rely on what is presented... I have found several discrepancies...

[Jacksonbrown]

Don't know how to check java script. Are you saying they are more accurate? I just used the formulas I could see.

[rad14701]

Don't know how to check java script. Are you saying they are more accurate? I just used the formulas I could see.

In most web browsers you can view the HTML and Javascript code that renders the page by Right-Clicking and selecting "View Page Source", "View Source", or something to that effect... For example, on the http://homedistiller.org/calcs/calc" onclick="window.open(this.href);return false;" rel="nofollow page, the Vapour-Liquid Equilibrium formula displayed is incomplete... It should read %vap = -94.7613*x ^ 8 + 450.932 * x ^ 7 - 901.175 * x ^ 6 + 985.803 * x ^ 5 - 644.997 * x ^ 4 + 259.985 * x ^ 3 - 64.5050 * x ^ 2 + 9.71706 * x + 1.2824424781005507E-4 and, as you can see, the + 1.2824424781005507E-4 was missing on the rendered page... This might help explain why your calculations were off and in need of tweaking...

[Jacksonbrown]

If that is all then I can see why it was left off.
Adding 0.0001282 to the end result is a bit of a superfluous step. It is likely it was just to make 0% sit exactly on 100°C
Rounding to the nearest whole number in the calculator does that anyway.

I used the equations regardless.
The point is that those equations look like someone has just fit a curve to a data set in exactly the same way I did.
The Perry table stops at 95.5°C so not that i guess (or was the next point just 0@100°C?)
If that is the case then I should start with that data set rather than the best fit equations derived from it.
What is the history behind the equations? or is that lost in time?

[rad14701]

What is the history behind the equations? or is that lost in time?

Lost in time, I'm sure... Those were pre-2000 (or thereabouts) calculations that Tony Akland compiled into his original site... Where they came from is unknown... He may have scrounged them up from elsewhere or he may have derived them himself... But there are similar formulas for phase diagrams scattered about the internet and in textbooks...

[Jacksonbrown]

So using the Perry data and adding 0@100°C Excel gave me this

y=60.046x^4 - 162.09x^3 + 163.16x2 - 83.21x + 99.981

And ZunZun this

y=60.046218651198444x^4-162.09452555086926x^3+163.16385637528785Ex^2-83.210343349298128*x+99.981

[rad14701]

So using the Perry data and adding 0@100°C Excel gave me this

y=60.046x^4 - 162.09x^3 + 163.16x2 - 83.21x + 99.981

And ZunZun this

y=60.046218651198444x^4-162.09452555086926x^3+163.16385637528785Ex^2-83.210343349298128*x+99.981

I'll try tossing those into my Javascript calculator to see how they compare to the original posted on the parent site...

[Jacksonbrown]

And with the intercept pinned to 100°C

y = 60.46x^4 - 163.02x^3 + 163.87x^2 - 83.42x + 100

vs the parent sites

y= 60.53x^4 - 163.16x^3 + 163.96x^2 - 83.44x + 100

Plus that perry data has some distinct kinks in it when plotted that are lost in these best fit equations.

[Jacksonbrown]

I'm a dickhead I just realised that's what that chart at the bottom of the page is

I'm not sure why I don't get the same equation but it's pretty damn close. Perhaps the Perry data is rounded and he used the original.

[Jacksonbrown]

With what I learned over the last few days I think this is the equation to use.

V=1.00234870142762+0.00448539174680633*(T+A*F)^2/((T+A*F)^2-76.8192824761981^2)+0.167549870972697*(T+A*F)^2/((T+A*F)^2-107.95147196715^2)


T=Temp in °C
V=%ABV of vapour
A=Altitude in metres
F=fudge factor (%0.34 for water or %0.31 for azeotrope, depends which end of the scale to you want more accurate) Just leave at 0m for no effect.

If you don’t want altitude, just leave out A&F.
This equation gives 100°C as exactly 0% and 78.1°C as 95.6% and it is derived from the original Perry data set so hasn’t been washed down along the way.

If anyone has better data I could go further but I think this is the end of the line.

[Johnny6]

When entering your "fudge factor", what would you actually enter for azeotrope into the calculation? Is the value in percent, or would the value be 0.0031 for azeotrope?

I've been curious about the contribution of altitude/ambient pressure into the calculations. Thanks.