Quick and dirty continuous still

[lthendricks8]

Hey guys,

I know there are several threads on these forums re: continuous builds. My situation is somewhat unique - I'm in a third world country facing a shortage of disinfectant alcohol during the COVID-19 pandemic, and my existing business is a moderate sized craft brewery. In an attempt to ameliorate the shortage + keep our lights on + keep my employees working, we've started fermenting molasses/sugar washes in our fermenters (this is the cheapest fermentable to which we have access), and I'm in a position to churn out tens of thousands of liters of ~13% abv wash per month.

Unfortunately, the only piece of distillation equipment we have is a (very) small 25L boiler w/ one 5.5kW element and a four-plate flute from a pilot distilling project we were beginning to experiment with before the world went south a few months back.

I'm not interested in making cuts - no one should be drinking this product. All I want to talk about is general design principles and DIY-style solutions that would allow me to optimize my existing still in to something that would allow us to maximize our output. I've already welded an inlet on to my flute (it's a modular design, but right now it's between plates 2 and 3). I've also purchased everything I need to feed wash from our fermenters, through a pump controlled by a VFD, through the HEXs on the column to pre-heat it to saturation and finally in to the column. I'll also say (because I'm afraid someone will voice their opinion) that I'm not terribly interested in discussing the ethical issues associated with trying to keep my business running during a pandemic - we practice excellent hygiene and social distancing in the manufacturing facility.

I'm trying to conceptually optimize a few things, subject to the limitations of being in a third world country and not having access to a lot of things even under the best of conditions but even moreso under the conditions I find myself in currently (most things locked down/closed, etc.). Two issues have come to my mind, but perhaps I'm missing some other obvious issues that I won't realize until I fire everything up and something goes wrong.

First, do I run the feed wash through both the dephlegmator and the condenser? If so, do I do it in parallel or in series? If I do so in series, is it better to run counterflow on both or should I run crossflow on the dephlegmator to ensure it doesn't run dry? Under what conditions would I have an issue balancing the system--i.e., is it possible that my flow rate (to ensure I'm not dumping alcohol out of my bottoms overflow by injecting too quickly) will be too low to effectively provide enough of a heat sink to condense all my product? Can this be solved simply be adjusting the heat input too, managing both variables in tandem? Is it possible that the system of balances will have no solution, and I'll be dumping an uneconomical portion of alcohol out with my bottoms?

Second, my bottoms collection will simply be a J-tube coming off of the lid of my boiler. The apex of the tube will be beneath my first plate so that I don't run the risk of flooding the column. I know that I should probably have a condenser on this line to stop vapor from exiting here, but I do not have a spare condenser (the only two I have are currently on the flute above the plates and then on the product side). How do I avoid vapor exiting the bottoms outlet? Is this even something I need to worry about once the column is in equilibrium?

Any other observations or thoughts on how to make a quick, dirty, fast continuous column for the production of cheap disinfectant alcohol would be appreciated. I have a chemical engineering degree but haven't used it in nearly fifteen years, and as I mentioned was in a related (beer) but realistically pretty different field before. All this is by way of saying I barely know what I'm doing, so assistance on anything would be great.

[LWTCS]

Hello,
Some of the boys helped me spitball some napkin math based on some known numbers of a much larger system that was designed using an ASPEN modeling program.

We figured about 408 watts per gallon , per hour is needed. If you factor in potential heat losses, it may be best to round up to 500 watts per gallon , per hour is needed? But we have not pinned that number down.

Naturally, any heat recovery / preservation you can do will help with the requisite amount of heat needed. So yes, circulating your beer through your HXs to use it as a cooling medium will act as a great way to preheat your beer prior to injection.

With only a couple of plates in your lineup, using your kettle to contribute to more dwell time under heat is a good idea. You'll want to give the alcohol as much time/opportunity to flash before it goes down the drain. But I don't think 2 or 3 plates (4 including your kettle?) Is enough to prevent a lot of alcohol from going down the drain.

Also, part of the problem with using your kettle and column bottoms as a steam source to flash alcohol is that molasses foams up terribly. Even with good degassing you should expect a foam up in your kettle to puke all the way over into your distillate.

I'm not sure what kind of design you've put together but my system runs by monitoring the low wines vapor temperature. Heat input remains constant. It is the beer feed pump speed that will determine the vapor temperature. So let's say you want a target temperature of 91C. Run the pump speed that gets you stable at 91. If you then conclude that vapor temps at 97 C are best to insure that you are not draining alcohol out of your kettle then simply slow your pump down to increase the head temperature.
Of course all of this is assuming you'll be able to get compliant hydraulic behavior out of your plates.

Got a diagram of your proposed mods?

[Yummyrum]

OK
Realistically , forget about what you are trying to do and just run the fermentented Molasses wash through the 4 plate still .


He’s my logic .

First off , a continuous stripping still will only get you close to 50% AVB ... and thats an efficient still... not a half arsed attempt ..
You’ll need at least 70-80% for Hand Sanitiser to be effective... so you would need to re-run the strip anyway .

You could easily get 90+ % AVB from a single run through your 4 plate still . .... run it harder and you could pull it at 80% AVB ready for Bottling .

As LWTCS said , Molasses is a bitch ... it foams up , its not a five minute job to cobble up a batch of stuff to deal with it . You need anti foaming agents etc to deal with it .

As also mentioned , 4 plates is not even going to make a dent in the iceberg . You need a whole lot more plates than that just to strip it continuously to 50% AVB .. then ... you got redistill it to 80+%


Bottom line . You got to use what you’ve got in the most time appropriate way.

Friggin around trying to get 4 plates to work as a Continuous still is pissing in the wind IMHO

Just use them to pump the shit out as a plated still and forget the continuous idea .iff’n that's what you want

[jdetechguy]

OK
Realistically , forget about what you are trying to do and just run the fermentented Molasses wash through the 4 plate still .


He’s my logic .

First off , a continuous stripping still will only get you close to 50% AVB ... and thats an efficient still... not a half arsed attempt ..
You’ll need at least 70-80% for Hand Sanitiser to be effective... so you would need to re-run the strip anyway .

You could easily get 90+ % AVB from a single run through your 4 plate still . .... run it harder and you could pull it at 80% AVB ready for Bottling .

As LWTCS said , Molasses is a bitch ... it foams up , its not a five minute job to cobble up a batch of stuff to deal with it . You need anti foaming agents etc to deal with it .

As also mentioned , 4 plates is not even going to make a dent in the iceberg . You need a whole lot more plates than that just to strip it continuously to 50% AVB .. then ... you got redistill it to 80+%


Bottom line . You got to use what you’ve got in the most time appropriate way.

Friggin around trying to get 4 plates to work as a Continuous still is pissing in the wind IMHO

Just use them to pump the shit out as a plated still and forget the continuous idea .iff’n that's what you want

What do you think about using a packed column versus plates? Would that be too restrictive?

[drmiller100]

Hey guys,

I know there are several threads on these forums re: continuous builds. My situation is somewhat unique - I'm in a third world country facing a shortage of disinfectant alcohol during the COVID-19 pandemic, and my existing business is a moderate sized craft brewery. In an attempt to ameliorate the shortage + keep our lights on + keep my employees working, we've started fermenting molasses/sugar washes in our fermenters (this is the cheapest fermentable to which we have access), and I'm in a position to churn out tens of thousands of liters of ~13% abv wash per month.

Unfortunately, the only piece of distillation equipment we have is a (very) small 25L boiler w/ one 5.5kW element and a four-plate flute from a pilot distilling project we were beginning to experiment with before the world went south a few months back.

I'm not interested in making cuts - no one should be drinking this product. All I want to talk about is general design principles and DIY-style solutions that would allow me to optimize my existing still in to something that would allow us to maximize our output. I've already welded an inlet on to my flute (it's a modular design, but right now it's between plates 2 and 3). I've also purchased everything I need to feed wash from our fermenters, through a pump controlled by a VFD, through the HEXs on the column to pre-heat it to saturation and finally in to the column. I'll also say (because I'm afraid someone will voice their opinion) that I'm not terribly interested in discussing the ethical issues associated with trying to keep my business running during a pandemic - we practice excellent hygiene and social distancing in the manufacturing facility.

I'm trying to conceptually optimize a few things, subject to the limitations of being in a third world country and not having access to a lot of things even under the best of conditions but even moreso under the conditions I find myself in currently (most things locked down/closed, etc.). Two issues have come to my mind, but perhaps I'm missing some other obvious issues that I won't realize until I fire everything up and something goes wrong.

First, do I run the feed wash through both the dephlegmator and the condenser? If so, do I do it in parallel or in series? If I do so in series, is it better to run counterflow on both or should I run crossflow on the dephlegmator to ensure it doesn't run dry? Under what conditions would I have an issue balancing the system--i.e., is it possible that my flow rate (to ensure I'm not dumping alcohol out of my bottoms overflow by injecting too quickly) will be too low to effectively provide enough of a heat sink to condense all my product? Can this be solved simply be adjusting the heat input too, managing both variables in tandem? Is it possible that the system of balances will have no solution, and I'll be dumping an uneconomical portion of alcohol out with my bottoms?

Second, my bottoms collection will simply be a J-tube coming off of the lid of my boiler. The apex of the tube will be beneath my first plate so that I don't run the risk of flooding the column. I know that I should probably have a condenser on this line to stop vapor from exiting here, but I do not have a spare condenser (the only two I have are currently on the flute above the plates and then on the product side). How do I avoid vapor exiting the bottoms outlet? Is this even something I need to worry about once the column is in equilibrium?

Any other observations or thoughts on how to make a quick, dirty, fast continuous column for the production of cheap disinfectant alcohol would be appreciated. I have a chemical engineering degree but haven't used it in nearly fifteen years, and as I mentioned was in a related (beer) but realistically pretty different field before. All this is by way of saying I barely know what I'm doing, so assistance on anything would be great.

Send me a msg if you still monitor this. I can help you