Continuous stripper power calculations

We don’t condone the use of Continuous Stripping stills as a method of running 24/7 as this is a commercial setup only .
Home distillers should never leave any still run unattended and Continuous strippers should not be operated for longer periods than a Batch stripping session would typically be run to minimise operator fatigue..

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manu de hanoi
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Continuous stripper power calculations

Post by manu de hanoi »

Hi all,
Here is an excel file I made (15 kb) for computing the power required for continuous stripping
http://www.stainlessstuff.net/up/contin ... ations.xls

here is the content :

Code: Select all

Power calculations for continuous stripper					
	water	etoh			
specif heat vapo 	2246000	841000	J/kg		
heating 	4100	2460	J/k/kg		

	 abv %	mass %			
out	40	34,46920052	boiling temp for output	96	C
in 	10	8,060067423			

ethanol density kg/l	0,789				
wash input rate	25	l/hour			
input wash temp	20	C			
spent wash flow rate	18,75	l/hour	6150000	J/hour	
output flow rate	6,25	l/hour			
mass flow rate for output etoh	1,699762451	kg/hour	317787,5878	J/hour	
mass flow rate for output water	4,095674967	kg/hour	1276212,32	J/hour	
		total	1593999,908	J/hour

Evaporation:		etoh	1429500,221	J/hour
		water	9198885,976	J/hour
		total	10628386,2	J/hour

grand total	18372386,11	J/hour		
power required	5103,440585	watts		
1) Can someone double check the calculus ?
2) some very interesting points :
-if the output abv can be raised from 40 to 50 % abv the power required drops from 5103 Watts to 4300 W (or a bit less considering the boiling point lowers too)
-by using a wash preheater to heat the wash from 20 to 50 C, the power required drops from 5103 Watts to 4288 W
- with 50% abv and a wash preheater, the power required drops from 5103 Watts to 3490 W
it's so good i would not be surprised if I made a mistake
kiwistiller
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Re: Continuous stripper power calculations

Post by kiwistiller »

pretty awesome results Manu. I might have a crack at checking your working tonight, though I'm likely to get confused and stop. :lol:
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Re: Continuous stripper power calculations

Post by jdpete »

I recently did a maiden run of a continuous stripper I constructed and my actual figures worked out to be 450ml of feed per minute at 4000 watts feeding with a 6% apple wine. Seems pretty close to your calculations. Although I was not preheating the wash. (I will next time) I ran 200 liters through it in one run.
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Re: Continuous stripper power calculations

Post by Lubavitcher »

jdpete please put up pictures and diagrams!
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Re: Continuous stripper power calculations

Post by jdpete »

It's nothing out of the ordinary. It's a bok head with a 20" stripping section below that is feeding just above the packing. It works and is setup just like the diagram on the home distiller site.

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Re: Continuous stripper power calculations

Post by Lubavitcher »

did you use any electronic controllers or pumps to force the wash in
"malt does more than Milton can, to justify G-d's ways to Man."

There is a famous story in which the Kaiser asks Bismarck, “Can you prove the existence of God?” Bismarck replies, “The Jews, your majesty. The Jews.”
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Re: Continuous stripper power calculations

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Trample the injured and hurdle the dead.
jdpete
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Re: Continuous stripper power calculations

Post by jdpete »

I used a peristaltic pump to move the liquid.
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Re: Continuous stripper power calculations

Post by kiwistiller »

calcs look good to me manu. I'm not especially good at the math game though. if someone else finds errors, can you let me know so I know where I went wrong?
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manu de hanoi
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Re: Continuous stripper power calculations

Post by manu de hanoi »

thanks kiwi
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Re: Continuous stripper power calculations

Post by manu de hanoi »

Fixed an error (mass flow rate of etoh) and added calculations for steam generator, reflux, and wash pre-heater.

I really need someone to review the calculus and especially doubt my calculus for the reflux. Basically my formula is explained here :
http://homedistiller.org/forum/viewtopi ... 5#p6844433" onclick="window.open(this.href);return false;" rel="nofollow

The problem is that reflux sent to the stripper needs to be reboiled so more alcohol will be generated and that extra fraction of reboiled steam will need reflux too and so on. In the end (i think) the formula is sigma(x^n) for n=1 to infinity. I dont know how to put that in excel so I just developed it up to n=10 and fortunately it seems to converge somewhere for numbers below 1. I'm not following any book but rather freestyling for all this excel file.

Conclusion :
The minimum mandatory reflux needed to reach 96% will double the power required for the stripper! That seems too expensive to be true, can someone recheck ?
http://www.stainlessstuff.net/up/contin ... tions2.xls
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Re: Continuous stripper power calculations

Post by Orville »

manu de Hanoi,

I’m pulling apart and studying your spread-sheet and I need a clearer definition of cell B14 [88˚C], labled as “input wash temp”, I was thinking it was wash pre-heat, but you have that defined at 78˚C elsewhere, so I don't know what I'm looking at there???

Thanks.
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Re: Continuous stripper power calculations

Post by jdpete »

I'm a little math illiterate. What would be cool is if you had pre-defined input boxes and output data and hide everything else on the sheet. I'm not quite sure how to input the data and where.

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Re: Continuous stripper power calculations

Post by manu de hanoi »

Orville wrote:manu de Hanoi,

I’m pulling apart and studying your spread-sheet and I need a clearer definition of cell B14 [88˚C], labled as “input wash temp”, I was thinking it was wash pre-heat, but you have that defined at 78˚C elsewhere, so I don't know what I'm looking at there???

Thanks.
Hi, depending on the method used to preheat (spent wash, reflux condenser, output condenser) you will get different pre heating temps, choose the one you want and set the temp to the value given by the pre heater calculus on the bottom of the spreadsheed
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Re: Continuous stripper power calculations

Post by manu de hanoi »

I got a request for the file because my links are dead, here's the file, it's probably full of errors, so don't trust it. I unfortunately havent had the opportunity to dive back in seriously and clean it up.
continuous stripper calculations.xls
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drmiller100
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Re: Continuous stripper power calculations

Post by drmiller100 »

For fun, run the math if your still outputs 95 percent alcohol.

Smiles!!!
Now I know how you claim azeo so easy, it's based on a meat thermometer. :lol:
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Re: Continuous stripper power calculations

Post by drmiller100 »

The spreadsheet is incredible.

I'd like some help examining the math of a reflex pot still. I get started amd get wrapped in a knot.

So, assume 10 percent wash, some arbitrary btu, refluxing to 95 percent, and a really tall packed column.

So, the vapor coming off the wash is 50 percent alcohol amd 50 percent water (from the charts)

We know the top of the column is 95 percent alcohol.

The liquid falling back into the boiler is 10 percent alcohol and 90 percent water (same temp as the boiler same percentage. )

So we can quibble, but basically all the energy to boil the water is wasted as it falls back in the boiler. And the energy to boil the water is 70 to 80 ish percent of the energy to boil the wash (the latent heat of vaporization of water is 3 or 4 ish times that of etoh.)

Are the charts by weight or volume?

If the wash is run down to 5 percent it gets really ugly from an energy pov.
Now I know how you claim azeo so easy, it's based on a meat thermometer. :lol:
manu de hanoi
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Re: Continuous stripper power calculations

Post by manu de hanoi »

drmiller100 wrote: Wed Dec 01, 2021 7:42 pm

So we can quibble, but basically all the energy to boil the water is wasted as it falls back in the boiler. And the energy to boil the water is 70 to 80 ish percent of the energy to boil the wash (the latent heat of vaporization of water is 3 or 4 ish times that of etoh.)
yeah that's the main idea, you can recover some of that energy though in a continuous still by using the wash as a coolant


Are the charts by weight or volume?
->I dont remember

If the wash is run down to 5 percent it gets really ugly from an energy pov.
->you can also recover spent wash heat
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Re: Continuous stripper power calculations

Post by LWTCS »

100% Manu.
Screenshot_20180810-131544.jpg
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manu de hanoi
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Re: Continuous stripper power calculations

Post by manu de hanoi »

oh you found a good simulation software ?
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Re: Continuous stripper power calculations

Post by LWTCS »

Well this example was rendered from a collaborative effort that is the baseline for what we/ I'm doing at the moment.
It is an ASPEN model.
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Re: Continuous stripper power calculations

Post by drmiller100 »

manu de hanoi wrote: Thu Dec 02, 2021 8:25 am
drmiller100 wrote: Wed Dec 01, 2021 7:42 pm

So we can quibble, but basically all the energy to boil the water is wasted as it falls back in the boiler. And the energy to boil the water is 70 to 80 ish percent of the energy to boil the wash (the latent heat of vaporization of water is 3 or 4 ish times that of etoh.)
yeah that's the main idea, you can recover some of that energy though in a continuous still by using the wash as a coolant

->you can also recover spent wash heat
Mine does all that and more. It uses a fraction of the energy you predict.

So with your stripper where is the wash added to the system? Boiler? Column? Mid column?

On edit I ran across your 45 degree cooler at the top from 2010.
We both ended up with very similar designs!!! I took mine a bit further but it does require a needle valve.
Now I know how you claim azeo so easy, it's based on a meat thermometer. :lol:
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Re: Continuous stripper power calculations

Post by manu de hanoi »

drmiller100 wrote: Thu Dec 02, 2021 6:21 pm

So with your stripper where is the wash added to the system? Boiler? Column? Mid column?
wash enters the column on top of the stripper, like all continuous strippers.but it shoudl be preheated by the reflux/condenser coil first and spent wash heat exchanger second (cause it's near 100C).
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Re: Continuous stripper power calculations

Post by drmiller100 »

I've been thinking about this for a few days.

How many plates do you have? I think it matters just like it Matters on a reflux still how many effective plates you have.

On a reflux column "enough" is an answer. If you have enough plates it will run as efficiently as it can, and adding more doesn't help. Likewise if you are running a reflux Still and have one or two crummy plates you will either never see 190 proof or you will have to run the thing really slowly.

Assume your stripper gizmo has enough plates, you SHOULD be able to have almost 100 percent water at the bottom.
The top plate is going to be the temperature of the feed input, which really is going to be determined by the alcohol content of the beer. So, if your wash is 10 percent by volume, the vapor will be about 50 percent alcohol.

It will take a lot of plates. It takes a lot of work to drive a wash below 5 percent. The differences in temp are minute, just like a reflux column.

In fact, my testing lead.me to input my beer in the middle of a 6 foot column, and of course the insertion temp was such that the wash was starting to boil in the lines.
Now I know how you claim azeo so easy, it's based on a meat thermometer. :lol:
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