Continuous stripping still

[violentblue]

Looking for a little feedback on a design I've been thinking of for a stripping column.
Planning on building the column itself out of 3" stainless, with marbles as packing. not planning on getting much reflux, just to slow the wash down a little.
all coils will be 3/8 copper.

Valvs are there ro try and regulate things some.



Plan is to cut the volume of material for final distilation down significantly, then do final distillation in a pot still making cuts as needed.

[Nykter]

To me it looks as if you have thought of everything. Maybe you wont need two valves for the wash entry...

Marbles or raschig are better because yeast residues wont stick as easily as they do to pot scrubbers or similar.

By not trying to reboil the spent wash you're avoiding to boil out more nasties from the yeast cells than necessary.

Im looking forward to hear about your results.

[HookLine]

Never built or used a stripper, but I though the best place to feed the wash in was about halfway up the packing, not at the top.

[alice]

I'd like to see it built...

[minime]

Maybe measure the spent wash temperature to be sure there's not too much alcohol left in there.

[Rudi]

Absinthe has built a continus stripper read about it here http://homedistiller.org/forum/viewtopic.php?f=1&t=5432

[Nykter]

Never built or used a stripper, but I though the best place to feed the wash in was about halfway up the packing, not at the top.

No, if its a true stripper the feed should be at the top.
The part of the column above the feed will be rectifying, not stripping. And to use that properly, you would need reflux too. A lot more complicated to tune in.

Yes, its a good idea to measure the temperature at the bottom. But dont measure the spent wash, it might have cooled off a bit. Be sure to measure steam inside the column.

[HookLine]

Never built or used a stripper, but I though the best place to feed the wash in was about halfway up the packing, not at the top.

No, if its a true stripper the feed should be at the top.
The part of the column above the feed will be rectifying, not stripping. And to use that properly, you would need reflux too. A lot more complicated to tune in.

I see. Learn something new everyday here. Thanks for that.

[Dan Call]

This is very interesting and I've thought alot about an initial stripping system that was fast and efficient to collect low wines then pot stilling or low reflux collumn stilling for flavor. It seems that large scale distilleries have continuous systems with the "beer stripper" steam fed from the bottom through collumn plates then the collected stuff going into low wine tanks then pumped into rectification collums of similar size. This does massive amounts of stuff.

The more traditional bourbon folks of days gone by, like Sitzel Weller, used a stripper for collection then a series of "pot doublers" as they called them. I'm not sure what works best, but if the flavor is any indication, pretty much anything out there really sucks badly, so there must be a better way to scale batches and maintain flavor.

But as for the system you've proposed here, a few questions/comments.

I'm wondering how the marbles are going to work with steam shooting up between them and the mash coming down, it doesn't seem like it's going to create the necessary slow-flow in order to get vapor separation. Wouldn't drilled copper plates with an overflow hole work better? The sheer density of the marbles is going to introduce a new variable as their temp will have a noticeable effect on the success of the whole vaporization process, it would seem. In other words, your 'marbles would need to be hot' for the system to work, wouldn't they?

Also, are you using the "mash input" vat as a defacto pre-heater for the mash?

Steam, the source has to be fairly precisely regulated in order to maintain the vapour pressure for the collumn to work consistently and get any type of consistent results and, again, the vapour separation, else you're going to be pouring alot of mash down the drown with ethanol still in it.

Again let me say....fascinating idea and the exact direction alot of us around here are thinking, especially with regards to batch processing for micro-distilling.

Mother Earth News has some stuff on this that I've found interesting.

http://journeytoforever.org/biofuel_lib ... meCh7.html" onclick="window.open(this.href);return false;" rel="nofollow

[Nykter]

I'm wondering how the marbles are going to work with steam shooting up between them and the mash coming down, it doesn't seem like it's going to create the necessary slow-flow in order to get vapor separation. Wouldn't drilled copper plates with an overflow hole work better? The sheer density of the marbles is going to introduce a new variable as their temp will have a noticeable effect on the success of the whole vaporization process, it would seem. In other words, your 'marbles would need to be hot' for the system to work, wouldn't they?

The properties of different column fillings apply to continuous systems in the same way as it does to batch systems, i.e the finer, the more area the better. The problem with yeast cells and other residues calls for using an inferior filling, marbles or better raschig rings since they dont collect residues that easy are easier cleaned.

The density of the marbles shouldnt be a problem, in a stabilized column they will be heated to the correct temperature by the steam.

Also, are you using the "mash input" vat as a defacto pre-heater for the mash?

A good idea, havent tried that in practice.

Steam, the source has to be fairly precisely regulated in order to maintain the vapour pressure for the collumn to work consistently and get any type of consistent results and, again, the vapour separation, else you're going to be pouring alot of mash down the drown with ethanol still in it.

Yes, correct. The amount of steam introduced corresponds to the heating power in a batch still. If you use to little steam, as you say you will be wasting ethanol. If you use too much, you will be wasting steam, and getting a diluted product out of your still. I have tried a system called AFC, (search for this) that uses the thermosiphon effect to feed the column with the correct amount of wash for a given heating power. The problem with this system is that it prevents preheating of the wash in the condenser.

[absinthe]

it looks great but with the setup you have:

a: i wouldn't bother with the fresh water condenser.. you will have better output doing is all with the wash (if your condenser is that big then the slow input of the wash will handle it)..

b: marbles, etc good for this setup

c: a temp sensor at the bottom will aid you in gauging the input speed

( i was gonna say don't use stem use the spent wash in the boiler but i haven't played with steam as yet to know the difference and i don't know if your going for vodka or flavour.. for me i use spent wash cause even in a single batch run strip i go right down to about 7-10% deeeeeeepppp into the tails)

[manu de hanoi]

-for 3'' i'd suggest 1,25m height or more. The more height, the faster you can push the device.
-SS packing is ok if you racked once or twice before for 100L/150L run. Just make sure you leave 2 cm void between the wash input and the packing.
-your wash condenser/preheater is wrong because the wash will run down as soon as it is in, to fix this put the wash input to the condenser at the bottom of the condenser and the pipe towards the column on top of the condenser. Surprisingly you did it correctly for the water condenser.

[violentblue]

response to some of you questions

Product I'm aiming for, rum mostly, with the possibility of Brandy occasionally.
so Yes I'm concerned about flavor loss from the steam injection, was hoping to offset this by running 50% stripped distilate and 50% wash in a poststill for final distillation and cuts.

Manu- I see your point, was hoping the valve on the output of the preheater would solve this issue, but yes the way you suggested would make filling the preheat chamber much easier.

I based this design on a modification I did on a Column still I built a while ago, same scenerio, I fed the wash in above the packing, but the outlet was at about the same level, which meant I'd have run the wash feed in slower or it'd just flow rightn through directly to the output. I added a valve to my boiler below, which then drained away the excess spent wash. The system did work, it was faster than running in batches, and the distillate was very flavorfull, and after a second distillation with proper cuts it turned out very well.

there were several changes I made to the design to address specific issues witht he original.

1. preheater: original lacked this feature and Just figured would be a good way to reduced the amount of wasted heat.
2. outlet raised above wash inlet: wash inlet was moved to above the packing material to eliminate as much reflux from the system as possible, wanting to keep as much flavor as possible. the outlet moved well above the inlet to avoid a direct path across.
3. increased colum diameter: first design had a 2" column, wich made for a fine balancing act between boiler tempurature, and the input of the wash, if the boiler was too high distillate came off watery, to low and not all the ehanol was removed, flow of wash too slow the distilate came off to watery, to fast and it'd flow directly through.
Larger diameter colum means more mass and surface area for thermal trasfer, the marbles used as packing are basically there to slow the wash down on its way to the bottom, and transfer the heat from the steam.

I thnk there is definatly room for improvement in the design, but this is just a first draft, I think there might be some wisdom in utilising a small boiler at the bottom, over steam injection, I'll just have to do some figuring and fabricating to make it work. The idea of using steam came out of the desire to remove the flame as far from the distillate as possible, I guess An electric heating element would be the next best thing.

[manu de hanoi]

-you can reuse much more heat by preheating the wash with spent wash than with distillate (spent wash will bring u half way from the wash temp to the boiling temp of water on a perfect exchanger), best is both
- I also would like to make steam injection because direct heating may cause some particles to burn and give bad flavors (maybe), do you have a design for the steam boiler ?
- By fear of having the steam going out through the spent wash output, i'd make a "n" shaped bend on the spent wash output pipe
- the 2 valve thing on the preheater will also have problem when CO2 will accumulate in it. It is best if opened to the atmosphere

[Dan Call]

The fact that you've designed and used a similar systems certainly invigorates the discussion, so to speak. I thought you were just spitballing. I have a few more questions, if you don't mind.

What are you proposing as a steam source/generator, and how controllable is that source?

In the previous system, what was your output/throughput per hour?

It looks like with this system you could just run batch after batch so long as the system pressure relative to input was consisten and got your separation.

[Nykter]

Example of a steam generator:

Tried this a couple of years ago.
The leftmost tube is the steam generator. Its electrically heated, amount of steam is controlled by controlling the power to the element.
I am using a part of the spent cooling water to keep the steam generator filled.

This setup doesnt use any preheating.

Swedish to English translation:

Code: Select all

Vattenånga         Steam
Etanolånga         Ethanol vapour
Kylvatten in       Cooling water entrance
Kylvatten ut       Cooling water exit
Mäsk               Wash
Drank ut           Spent wash exit
Strippat           Low wines

[violentblue]

that looks like a perfect low pressure steam boiler. I had been putting some thought into it, and so far had come up with a design that was way more complicated and wouldnt work near as good.

That looks like it'd be simple to fabricate as well, just need a section of stainless tube that would fit over the heater element. I would add a heat exchanger to preheat the boiler water with the spent wash.

Funny thing is when complete this wouldn't look much like a still at all.

[violentblue]

-you can reuse much more heat by preheating the wash with spent wash than with distillate

True, but my idea behind the wash preheat was more to save on water being used in the condenser, as well as gain in some preheat. preheating with the spent wash would be a good idea, but I'd have to figure out how to do it all with gravity, I want to avoid using pumps. The plan was to make the system as simple to operate as possible, one or two valves to control almost everything.

[manu de hanoi]

goddammit! just while i was reading your post a wild male spent wash heat recuperator just crawled near my feet, freaky ! Fortunately I could capture this magic moment with my webcam :

[Nykter]

Funny thing is when complete this wouldn't look much like a still at all.

It doesn't, but if a policeman showed up while running it, what should you tell him i is? A part of the house's heating system? The smell would give it away.

[manu de hanoi]

A nice continuous hobby still infomercial from 1894:
http://cnum.cnam.fr/CGI/page.cgi?4KY28.42/272/110/p.268

Note the very special regulator Q (on top of the condenser) which is filled with a volatile chemical. When the temp raises, the chemical turns into vapor and pushes the wash entry valve to allow for more wash.

[Nykter]

Beautiful.

It seems to sense the temp in the top of the column though.

[violentblue]

revised design

includes boiler and provision to feed boiler with spent mash or water depending on your wants or needs.

I'd think that making a rum or wiskey you'd want to use the wash, to keep the flavor undiluted as possible.
but a vodka or neutral water would be the best to use.

also the wash would have to be clarified before running on this rig, or it'd be a pain to clean afterwards.

[manu de hanoi]

nice job, dont forget the thermometer hole on the bottom.

the overflow for the boiler input from nykter 's design is very smart, i'll copy that !

[violentblue]

nice job, dont forget the thermometer hole on the bottom.

Havent included any controlls or extras on this drawing, also would need to have a parrot on the distillate output.
I was thinking of putting a thermometer at the bottom to measure the temp of the spent mash, and a thermostatically controlled valve connected to it to controll the mash feed. so in a sence the heating element controll will be the only point of adjustment once its all tuned in.

love to hear the feedback, I'd rather get everything taken care of on paper before I attempt to build it.

[manu de hanoi]

ps On my still the 2 condensers (properly called wine heater and refrigerant) are in line on top of each other, boka style. This would save you a lot of piping and casing and soldering, but it's less reusable than external modular condensers.

[violentblue]

have to look at boka's design again
thanks for the heads up
ease of fabrication would definatly be a plus

[manu de hanoi]

I was thinking of putting a thermometer at the bottom to measure the temp of the spent mash, and a thermostatically controlled valve connected to it to controll the mash feed. so in a sence the heating element controll will be the only point of adjustment once its all tuned in.

Or you can use the heat pipe shown on nykter's design, it 's a Riku's design for "AFC" automatic feed control.

[Nykter]

the overflow for the boiler input from nykter 's design is very smart, i'll copy that !

Not my design, I copied that from "Farbror Plast", a really bright inventor on the Swedish distillers forums.

The AFC is mine though, but truly a derivative of the ARC which was first invented by Farbror_Plast, and further developed by Riku.

Whats the function of the three-way valve? I dont think you should mix spent wash with the steam generation system, to avoid reboiling yeast cells. if you do, you could use spent wash only for steam generation, you willsave on energy doing that.

Create an overflow exit "waterlock" for the spent wash too, and maybe connect the exits further down to cool the spent wash making it smell less, and being nicer to your plumbing.

Also be sure to insert the wash into the center of the column, if you follow your drawing it is inserted at the column wall, which might make it follow the wall, reducing column efficiency.

[manu de hanoi]

the overflow for the boiler input from nykter 's design is very smart, i'll copy that !

Not my design, I copied that from "Farbror Plast", a really bright inventor on the Swedish distillers forums.

The AFC is mine though, but truly a derivative of the ARC which was first invented by Farbror_Plast, and further developed by Riku.

I need to create a thread for that.... http://homedistiller.org/forum/viewtopi ... =17&t=7898