semi continuous column design

[yudpray]

Hi guys..
I am preparing to build a distiller.
I am only interested to distill alcohol for fuel, so i don't really concern about the cuts.

Do you think that stainless steel 201 is safe for distilling 95% alcohol?
I read somewhere that it is food grade, but alcohol distilling is a whole
different level.

I want to build a semi continuous still, so i make mash inlet above the
stripper to fill up the mash to the still and i make water collecter at the
bottom to prevent it from getting back to the boiler. My assumtion is that
at the bottom temperature only water will be liquid and if i can get rid of
it i can mantain alcohol concentration in my boiler.

It is not really fully continuous actually (that is why i call it semi
continuous), i just want to add more mash easily without have to open the
boiler. Since i only have small boiler.

I make a little bit tweaking in my design different than usual.

First, i make mash inlet above the stripper so i can refill the mash to the column easily without having to open the boiler.

Second, i use bokabob LM plate design to tap distilled water below the stripper. I assumtion is that only water will be condensed in that area since the temperature is almost 100 Celsius.

How do you guys think about my design? will it work?

What problem do you think will occur with my design?

do you think i will be able to distill at least 99% pure water from the
water outlet below the stripper?


I will really appreciate any critics and advices

[der wo]

Why need the stainless be food grade if you only want to produce fuel?

To get distilled water will not work. It will contain fusel oils and solids of the mash from the mash tank. Perhaps it's better if you install a drain at the boiler. This sounds like if you don't have much knowledge about distillation. If it is your first still, stop your plan and build a simple potstill first. Then a normal VM. And then perhaps if you still think you want a continuous stripper, build it. If you start from zero to a continuous setup you will make many mistakes, loose much time and money, and you will not reach faster your goal.

[rad14701]

Your continuous stripper will not work efficiently as you have sketched it... Those slant plates will direct virtually all liquids out the drain rather than reboiling... Also, most continuous strippers don't have a large boiler at the bottom... If you are truly set on running a continuous reflux column then perhaps you should research designs which are proven to work... The design you have proposed would be terribly inefficient compared to other designs...

[yudpray]

Why need the stainless be food grade if you only want to produce fuel?

To get distilled water will not work. It will contain fusel oils and solids of the mash from the mash tank. Perhaps it's better if you install a drain at the boiler. This sounds like if you don't have much knowledge about distillation. If it is your first still, stop your plan and build a simple potstill first. Then a normal VM. And then perhaps if you still think you want a continuous stripper, build it. If you start from zero to a continuous setup you will make many mistakes, loose much time and money, and you will not reach faster your goal.

About food grade, I just want to be safe, maybe in the future i want to use it for something else, so i don't have to build another still. That being said, do you think SS 201 is safe for making alcohol other than drink, for example: parfume solvent, antiseptic, in pharmacy. Because the price diffference is quite a lot between SS 304 and SS 201.
Yes, i am novice in this field, but that is actually the design in this parent site (in here http://homedistiller.org/equip/cont" onclick="window.open(this.href);return false;" rel="nofollow). the only different is the distilled water outlet. I don't really looking into tapping the distilled water for any other purpose other than to prevent it going back to the boiler and dillute my boiler's alcohol concentration. So, i think i asked the wrong question before. Maybe the better question is:

Will the water outlet contains much alcohol? if not then i am achieving my goal. I don't really concern what is in the water out other alcohol.

Btw, you don't mention the mash inlet in the middle of the packing, so will it work?

Maybe i am little bit greedy going from zero to continuous setup, It is purely because budget limitation. Thanks for your advices.

Your continuous stripper will not work efficiently as you have sketched it... Those slant plates will direct virtually all liquids out the drain rather than reboiling... Also, most continuous strippers don't have a large boiler at the bottom... If you are truly set on running a continuous reflux column then perhaps you should research designs which are proven to work... The design you have proposed would be terribly inefficient compared to other designs...

Ok, i'll give up the slant idea and go to make drain at the boiler instead as yo advised me.
What about the mash inlet in the middle of the packing, will it work?
btw, thanks for the advices guys, it's really helping.

[shadylane]

The lower grades of SS should work all right for fuel alcohol production.
Your only worried about corrosion
I might be pouring gasoline on my panties It may also be good enough for drinking alcohol.
One problem you may not of thought of.
The design you want to use, will have all the sediment down where the electric heater is.
I learned to think about things like that the hard way

[rad14701]

Ok, i'll give up the slant idea and go to make drain at the boiler instead as yo advised me.
What about the mash inlet in the middle of the packing, will it work?
btw, thanks for the advices guys, it's really helping.

You definitely want the wash inlet to be close to the center of the packed column rather than down low or up high so there is good separation of water and alcohol... The majority of alcohol should separate and rise while the water and a little alcohol drops to the bottom where the alcohol boils off an rises again while the water exits the overflow port... If memory serves me correctly an efficient continuous still should have somewhere around 3% alcohol in the waste water... I still think you should forego the keg and integrate a much smaller reboiling reservoir at the bottom...

[yudpray]

Ok, i'll give up the slant idea and go to make drain at the boiler instead as yo advised me.
What about the mash inlet in the middle of the packing, will it work?
btw, thanks for the advices guys, it's really helping.

You definitely want the wash inlet to be close to the center of the packed column rather than down low or up high so there is good separation of water and alcohol... The majority of alcohol should separate and rise while the water and a little alcohol drops to the bottom where the alcohol boils off an rises again while the water exits the overflow port... If memory serves me correctly an efficient continuous still should have somewhere around 3% alcohol in the waste water... I still think you should forego the keg and integrate a much smaller reboiling reservoir at the bottom...

That is exactly what i am thinking about. If i have 1,5 meters (5 feet) of packed column, where the inlet should be?

The lower grades of SS should work all right for fuel alcohol production.
Your only worried about corrosion
I might be pouring gasoline on my panties It may also be good enough for drinking alcohol.
One problem you may not of thought of.
The design you want to use, will have all the sediment down where the electric heater is.
I learned to think about things like that the hard way

I am not gonna use electric heater, i am going to use external LPG heater. So i hope i don't have that problem.

[thecroweater]

Is 201 safe well yeah in the short to moderate time frame. Alloys like 201 have been made to reduce cost and how that is achieved is to supplement nickel and chromium for magnesium and nitrogen. What that means is in a damp environment the as will be much more susceptible to pitting and rust. Not a big deal in the short to moderate term for fuel production but I'd be a little weary to consume anything from it. That said if you are going to make a continuous column realistically it will be a continuous stripper and you are going to need another still, even if just a pot to make your cuts on. There are some even more complicated, complex designs to get around that but not with the still you are contemplating.

[der wo]

What about the mash inlet in the middle of the packing, will it work?

It depends. For example looking at the long continuous columns for whiskey, the inlet is almost on the top of the column. But they don't use a dephlegmator and are happy with 60% abv. You need the length upper the inlet for purity and the part downer the inlet for efficiency (that you don't loose much of the alcohol).
It will be hard to control. VM-valve, inlet valve, waste outlet valve, heat input. You are playing with too many variables. And all the new things for you...
And the packing will get dirty during the run, what will affect the function. Normally a continuous setup uses plates. Less efficient but it will not plug.
Do you want to sell the fuel?

[yudpray]

Is 201 safe well yeah in the short to moderate time frame. Alloys like 201 have been made to reduce cost and how that is achieved is to supplement nickel and chromium for magnesium and nitrogen. What that means is in a damp environment the as will be much more susceptible to pitting and rust. Not a big deal in the short to moderate term for fuel production but I'd be a little weary to consume anything from it. That said if you are going to make a continuous column realistically it will be a continuous stripper and you are going to need another still, even if just a pot to make your cuts on. There are some even more complicated, complex designs to get around that but not with the still you are contemplating.

What about the mash inlet in the middle of the packing, will it work?

It depends. For example looking at the long continuous columns for whiskey, the inlet is almost on the top of the column. But they don't use a dephlegmator and are happy with 60% abv. You need the length upper the inlet for purity and the part downer the inlet for efficiency (that you don't loose much of the alcohol).
It will be hard to control. VM-valve, inlet valve, waste outlet valve, heat input. You are playing with too many variables. And all the new things for you...
And the packing will get dirty during the run, what will affect the function. Normally a continuous setup uses plates. Less efficient but it will not plug.
Do you want to sell the fuel?

Yes, after all of your advice i think will revise my design to the standard VM still that has been proven working. Thanks for the sharing of knowledge.
It is actually a hobby and i don't plan to sell the fuel in the near future.

Thanks guys, i will update my progress very soon (hopefully).

[der wo]

Yes, after all of your advice i think will revise my design to the standard VM still that has been proven working.

We often have new distillers with plans for a continuous setup. Not all are wise enough to reconsider it after our responses.

One more idea for you:
You will be faster if you double distill your spirit. When you have a wash for 3 runs, it's faster to do 3 stripping runs and one spirit run, than 3 spirit runs. You can use your VM for stripping too. You have to take out the valve or guarantee and quadruple check, that it is always!!! open. And then seal the top of the column, no packing, no water through the reflux condenser, column insulated (as always, the column should be insulated always). For fast stripping your product condenser has to be a bit larger than for a VM, it has to knock down all the power you throw in.

When you have the new ideas sorted, you can open a new thread and we will help you.

[yudpray]

Yes, after all of your advice i think will revise my design to the standard VM still that has been proven working.

We often have new distillers with plans for a continuous setup. Not all are wise enough to reconsider it after our responses.

One more idea for you:
You will be faster if you double distill your spirit. When you have a wash for 3 runs, it's faster to do 3 stripping runs and one spirit run, than 3 spirit runs. You can use your VM for stripping too. You have to take out the valve or guarantee and quadruple check, that it is always!!! open. And then seal the top of the column, no packing, no water through the reflux condenser, column insulated (as always, the column should be insulated always). For fast stripping your product condenser has to be a bit larger than for a VM, it has to knock down all the power you throw in.

When you have the new ideas sorted, you can open a new thread and we will help you.

Thanks for the idea der wo, so it will be safe if i seal the top as long i ALWAYS OPEN the valve right. Your idea sounds like a potstill for me. What if i build another potstill and connect the product output to the boiler of my reflux still?

[still_stirrin]

...so it will be safe if i seal the top as long i ALWAYS OPEN the valve right. Your idea sounds like a potstill for me. What if i build another potstill and connect the product output to the boiler of my reflux still?

Your question sounds like putting a reflux head & column on a thumper....right? A thumper (also known as a "doubler") acts like a secondary boiler powered by the hot vapor output from the primary boiler. Several members have added a reflux column to a thumper...look to the potstill and thumper forum for the discussions.
ss

[der wo]

Your idea sounds like a potstill for me. What if i build another potstill and connect the product output to the boiler of my reflux still?

Yes, it is the potstill mode of a VM. Of course you could build in addition a potstill. I have a potstill too for stripping, I use the same boiler and hotplate for it. But you want to run it at the same time, so you would need two boilers and two heating sources. Expensive, and it becomes almost as complicated as your continuous still plan. Perhaps more complicated, because the abv coming from the potstill will drop during the run, so you have to react with the other parameters. And for time efficiency you should have the potstill in theroy three times larger than the VM, that you can run three stripping runs and one spirit run at the same time. But in pratice for safety the VM should a bit larger than 1/3 of the volume of the potstill, because if it is too small, it could get overfilled. A sightglass at the VM-boiler would help to maintain a constant fill level. IMO it gets more and more complicated and more and more expensive... The good news is, that if you start to build a normal VM, you can always upgrade.

[The Baker]

I seem to remember that whisky distilleries use a big pot still (or several pot stills) feeding into a smaller pot still....
Geoff

[yudpray]

...so it will be safe if i seal the top as long i ALWAYS OPEN the valve right. Your idea sounds like a potstill for me. What if i build another potstill and connect the product output to the boiler of my reflux still?

Your question sounds like putting a reflux head & column on a thumper....right? A thumper (also known as a "doubler") acts like a secondary boiler powered by the hot vapor output from the primary boiler. Several members have added a reflux column to a thumper...look to the potstill and thumper forum for the discussions.
ss

Your idea sounds like a potstill for me. What if i build another potstill and connect the product output to the boiler of my reflux still?

Yes, it is the potstill mode of a VM. Of course you could build in addition a potstill. I have a potstill too for stripping, I use the same boiler and hotplate for it. But you want to run it at the same time, so you would need two boilers and two heating sources. Expensive, and it becomes almost as complicated as your continuous still plan. Perhaps more complicated, because the abv coming from the potstill will drop during the run, so you have to react with the other parameters. And for time efficiency you should have the potstill in theroy three times larger than the VM, that you can run three stripping runs and one spirit run at the same time. But in pratice for safety the VM should a bit larger than 1/3 of the volume of the potstill, because if it is too small, it could get overfilled. A sightglass at the VM-boiler would help to maintain a constant fill level. IMO it gets more and more complicated and more and more expensive... The good news is, that if you start to build a normal VM, you can always upgrade.

My conclusion is that i will just build normal VM and see if i it works the way i read it in HD while learning to control it.

[Seb]

Gentlemen, I wish to make fuel alcohol too. My project is to produce up to 48.000 litres (13,000 gallons) during the 6 months of the sugar cane season. I understand I need such a continuous stripping still : http://homedistiller.org/equip/cont" onclick="window.open(this.href);return false;" rel="nofollow - it seems to be the simplest and thus the most flawless design of all - it would be heated by a mix of wood and cane straw direct fire below the "small" boiler. How would you scale it to eventually produce the 360 litres per day of 90% ethanol?
Your help will be very appreciated.

[Saltbush Bill]

it seems to be the simplest and thus the most flawless design of all

It all looks very simple doesn't it, my opinion is that the opposite is true, there is a reason that there are hardly any continuous strippers used or working on the hobby forums. If anyone can show me a good working example that is used regularly Id love to have a look at it.

[Seb]

I'd love that too. It's true that posts about that always end ... unfinished which is frustrating. The one I put the link of seemed to be used tho.

[Yummyrum]

Seb
From my undestanding if them , they are a critical balancing act of boiler power and wash feed rate and wash preheating .
Having a direct fire burning cane waste would be a major variable to control.

There is a major issue with continuous strippers operating 24/7 ....: its totally unacceptable by this form on safety grounds .

OK if someone wants to run one for several hours a day while standing next to it watching it .

[Seb]

Seb
From my undestanding if them , they are a critical balancing act of boiler power and wash feed rate and wash preheating .
Having a direct fire burning cane waste would be a major variable to control.

Sure but we expect the mash to boil in the kettle. The system is not pressurized: too much heat = less pure alcohol up there, I agree on that. But since we are stripping and not yet rectifying, is it a problem? Also, after a while - and not necessarily a long while - wouldn't we be able to fine tune that too, just by habit?

There is a major issue with continuous strippers operating 24/7 ....: its totally unacceptable by this form on safety grounds .
OK if someone wants to run one for several hours a day while standing next to it watching it .

Of course. Not only a person but also a sensor/alarm at the outlet of the overflow in case the flow is interrupted. The person can squeeze cane next to that operation during the day.

[Cu29er]

Will you have a lot of solids in the wash? Solids and a packed column lead to plugging which leads to bursting boiling hot liquid spraying everywhere and scalding you the operator who is right next to trying to figure out why no output when the thing is rocking and rolling in the kettle. (Grain side, if not all the starch gets converted to sugar that starch becomes a sneaky plugging risk).

Much safer is a two stage system where you use a simple pot still design on the first run to collect all the output into a barrel and then separately run that clear and already condensed (but under 40proof) liquid through a packed column system to reach your high % target.

[Seb]

Will you have a lot of solids in the wash? Solids and a packed column lead to plugging which leads to bursting boiling hot liquid spraying everywhere and scalding you the operator who is right next to trying to figure out why no output when the thing is rocking and rolling in the kettle. (Grain side, if not all the starch gets converted to sugar that starch becomes a sneaky plugging risk).

Much safer is a two stage system where you use a simple pot still design on the first run to collect all the output into a barrel and then separately run that clear and already condensed (but under 40proof) liquid through a packed column system to reach your high % target.

Not that much solids. I could also flush/clean the column every day. The basic design you describe was my first option but since I have to produce some 360 litres / 95 gallons of pure alcohol a day, my boiler would have to be giant

[Expat]

Out of curiosity, you said in your first message 90% ABV (10% water) and in your last message Pure alcohol i.e Azeotrope. So you'd still have roughly 5-10% water in your fuel.... Which is a lot.

Are you sure whatever you're planning to fuel can handel that much water, or are you planning to further process the results to dry it?

[Seb]

Out of curiosity, you said in your first message 90% ABV (10% water) and in your last message Pure alcohol i.e Azeotrope. So you'd still have roughly 5-10% water in your fuel.... Which is a lot.

Are you sure whatever you're planning to fuel can handel that much water, or are you planning to further process the results to dry it?

A car will run with 85% alcohol. 90% is better. 96% being top. But 90% is good enough.

[zapata]

There are readily available text books covering industrial distillers design, as well as many patents and academic papers. Why are we even discussing something so far beyond the skill and experience set of home distillers? A proven design far beyond hobbyist conjecture is probably a dime a dozen amongst people who work in the industry. Good thing they tend to publish a lot of resources.

I suspect it is because the industry norms are too expensive or too complicated. But if it could be done just as well cheaper or simpler, the industry has far more motivation to have already figured it out than we do.

Maybe take a look here for a variety of sources
https://aussiedistiller.com.au/books/" onclick="window.open(this.href);return false;" rel="nofollow

[DeepSouth]

I think your biggest issue is fermentation. You'll need to process something like 1000-1500 gallons of fermented wash per day.

Your column will need probably need to be around 10 to 12" on diameter and maybe 15-20' tall.

As has been said, continuous columns need steady operating conditions. Your beer feed rate needs to be constant, and at a constant feed temperature. Your heat input needs to be constant as well, which will be difficult by burning biomass.

[Saltbush Bill]

I think your biggest issue is fermentation. You'll need to process something like 1000-1500 gallons of fermented wash per day.

The logistics of how to cut, transport and crush that much cane each day are also a little mind boggling.

[cob]

Out of curiosity, you said in your first message 90% ABV (10% water) and in your last message Pure alcohol i.e Azeotrope. So you'd still have roughly 5-10% water in your fuel.... Which is a lot.

Are you sure whatever you're planning to fuel can handel that much water, or are you planning to further process the results to dry it?

A car will run with 85% alcohol. 90% is better. 96% being top. But 90% is good enough.

if you are referring to e85 fuel, the other 15% is petrol and other hydrocarbons not water.

[StillerBoy]

A car will run with 85% alcohol. 90% is better. 96% being top. But 90% is good enough.

In agreement with cob.. E85 is not 85% alcohol and 15% water.. there is no water, as it is either filtered out, which can be done on a small scale using a water filter used on a car/tractor or removed in other manners which the industry does..

There is much research to what you are proposing to do..

Mars