1000L / 500L Pot Still Config Advice

Hi all,

Longstanding home-stilling lurker building my first small commercial setup in Budapest. We're expanding off an existing brewery, looking to convert our extra capacity into around 200L/week of CS juice, barrelled full-size for 3-10yrs. The build is pretty well-defined already, but I've got a couple outstanding questions I'd love to run by the huge wealth of experience on here.

We currently have about 2400L/week of wash capacity which will first go into a ~1000L pot for stripping down to ~30% ABV, and then be double-batched into a ~500L pot for spirit run to ~65% ABV entry strength. Both stills will be fired by direct electric elements, 30kW on the strip and 20kW on the spirit (reduced via PID after heating).

Our wash is very clean so we're keen to keep as much character on it as possible, with the exception of peated mashes where we'll get a little creative with passive reflux. As a result, we're planning pretty standard Scottish-style superstructures using SD copper helmets straight into lynes and condensers.

For the 1000L (600-800L wash charge, 30kW run, 60L/hr) we're planning a semi-custom 8" copper helmet with a 4" top, lyne, and condenser. For the 500L (300-400L low wines charge, 10kW run, 30L/hr) I'm planning to canibalise my home still with an old-style SD 4" copper helmet, which exits & condenses at 2".

Condenser numbers all work out fine on paper (helps that we're running glycol), but I'm a bit wary of running the 4" helmet that fast/hot. Typically at home it pukes wash above 3kW but is fine on low wines up to 4-5kW -- I'm just worried that anything north of 5kW is going to ram vapour through too fast for even minimal sulfate binding & passive reflux on the helmet.

I've had trouble finding vapour speed numbers for pot stilling -- presumably because of the subjectivity of it all -- so thought I'd ask the hive mind here. Should we be looking at a larger helmet and diameter for our spirit still? For that matter, do any of the above numbers look wonky? Happy to hear any thoughts/suggestions you guys have on the setup!

Thanks in advance!

Comments

  • 12" column for your 1000L and 8" for your 500L is what I'd recommend. I run my 1000L strip at 51kW and 500L spirit 12 (heads)-18(hearts)kW.

    Since you're running it as a pot it really doesn't matter though. 2" would be fine too (especially for the stripping run) and if it's foaming/puking just put some antifoam in it.

  • It sounds like it’s under powered and under refluxed with the copper head. And a 2” exit on that size still right out of the head would be way small and bottle neck it in my mind.

    For reference I was running a more size optimized 4” column with a really small 140l boiler pushing 15kw on heat up and operating at 11kw on a strip.

    I think I’d want a big ass 36” whiskey head fed thru at least 8” (agree 100% with @jbierling here) with an exit stepping down over some length to 2-3” right before the condenser. (See attached pic). I don’t think it all has to be copper tho. Maybe just the whiskey head itself. You could increase possible reflux by pointing a fan at the cooling section. That’s usually good for a few more percent.

    I think you could get creative on the passive reflux area before the condenser with modular parts but you may have to spend for a decent sized whiskey head or equivalent. Hell you may be better off with an 8” 4-6 plate reflux section and just do it all in one run.

    A pointer on the direct electrical elements. Make sure you use ALL ultra low watt density elements. It will reduce cavitation and thus foaming. It makes a really big difference in run speed and frustration.

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  • Thanks guys! Exactly the sort of feedback I was looking for, I've got column wattage & vapour speed numbers but not much idea how those relate to sizing for passive reflux on a whiskey head.

    On our spirit still we can easily upgrade to an 8" head with 3" exit and increase our condenser size to match. As for underpowered, how much power would you be running through this? I've been thinking 20kW heat & 10-15kW run on the basis of a 1hr heat & 3-4hr run, and our pot volume is sized to take 2 batches off the strip and run them together. We could size down to 250L but that adds labour and doesn't save us that much space or money.

    For our wash still, I'd like to push 30kW through the run, possibly more for the heat-up; we're aiming to strip 2x 600L batches/day through here. Obviously reflux is less important on this and we can anti-foam, but it sounds like you'd advise a 12" copper head here? Condenser is a big 4", so we'd exit at either 4" or 6" and step down.

    Our elements are all ULWD, 23 or 35W/in2 depending on boiler width, with agitators on all vessels to speed the heat-up.

    We'll be building a 250L with a couple 6" columns & a gin head as well, but we want to keep our primary whiskey production passive for now (and the column boiler is going to be too crowded to tack on an 8" copper).

  • I think you'll want a bigger condenser for your stripping run. A 1000L still should have a 8-12" condenser and a 500L still should have 6-8" IMHO. 4" would probably be OK for your spirit run.

    I really don't think vapor piping (piping between your still head and condenser) size matters all that much. All of mine is 2" and I push up to 1/gal a minute of product through it.

  • Thanks @jbierling !

    As I understand it these are really questions of power, not boiler size. We're still working the numbers on this but the current plan is to 2-stage the condensers with the first running municipal water and the second running our spare glycol capacity. Using two 4" x 510mm SD condensers, homedistiller's calc gives me a total combined flow around 10L/min to eat 30kW of power on our stripping runs.

    On our 500L spirit still, we can condense 15kW using two 3" x 510mm SD condensers in the same 2-stage setup. That gives us the same roughly 10L/min total flow requirement.

    We'll have a look at upsizing those condensers, 6" on the strip and 4" on the spirit would save us a good chunk of water and give us a bit more surface area on the lyne arms. In an ideal world we'd use 100% glycol chilling, but unfortunately our space for outdoor equipment is almost nonexistent here (we're in the city center and subject to a ton of district & condominium regulation).

    I agree that our vapour piping diameter isn't that influential, 1gal/min through 2" is pretty impressive!

  • Personally I would use nothing less than a 100mm diameter vapour line otherwise flow velocity is way too high which as far as I am concerned will result in unwanted smearing

  • You're right of course, a condenser is responsible for dealing with a certain amount of power. But, a condenser is also responsible for doing that in a reasonable amount of time and as your still gets bigger, it's going to take more time.

    So, if your condenser can condense 1/2 liter a minute and you want to condense 200 liters of liquid out of a 1000L still, that's going to take nearly 7 hours ignoring heat up and clean up. A 500L still might be perfectly fine.

    I had my 1000L still hooked up to my 6" condenser before I got my 12", and it was way too easy to over power the 6". Your glycol setup may be a different story though.

  • Yeah, we're looking for 150-200L low wines from 600-800L charge in our 1000L (~3hrs at 60L/hr), and 100-150L high wines from 300-400L charge in our 500L spirit (~4hrs at 30L/hr).

    Sounds like you're pushing product a fair bit faster than we're planning, but you're right that we could probably use a chunk more condenser capacity on the strip. Probably worth bumping up to a 12" head and 40kW there to help with our wash bottleneck, and we'll need the condensing capacity to match.

    51kW on the strip is pretty angry, I can see how you'd overwhelm some cooling there. How long is that 6" you overcooked?

    @richard Cheers, agreed on the smearing. Minimum lyne diameter would be that of the condensers, so probably 6" (152mm) on the strip and 4" (102mm) on the spirit.

  • I don't get the smearing comments. Hydraulic law says the vapour will speed up to pass a constriction.

    Not sure if the vapour is coming off the top of the wash at the volume dictated by the power level, and is being taken to the condensor and condensed at the same volume that it is forming then how is the smearing introduced? And who gives a fuck about smearing on a stripping still where you are putting all the strip back in for another run and smearing it all together anyway?

    And really? 6" piping? It will add a lot to the cost for no benefit i can see, but it's your money and your equipment.

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • @punkin Good point, thanks for weighing in. I guess smearing is the wrong term here; my thinking was more that ramming vapour fast through a (non-descending) lyne would diminish passive reflux and result in a messier strip overall. You'll know far better than I though how much that matters compared to the head reflux.

    Space is limited here so we're not planning huge lyne arms; on a 1m run the upgrade from 6" to 4" would cost about 250USD extra in the spool and bend. If we run 4" from the head and expand it back to 6" we need about 120USD in steel plus maybe 30USD in packing material to prevent channelling.

    Not saying I wouldn't pick up 100 bucks from the pavement though, so point taken :)

  • edited February 23

    That's not a lot of money, so maybe the expense is not the issue. If you go to my store, a 2" clamps is $10 and a 6" one is $70 though.
    I'm no expert for sure, but all our systems are 2" piping here, i think it looks neater and i just haven't had any feedback that would make me change it..

    If you are worried about vapour speed you could put a small expansion chamber before the condensor as it will slow back down after the constriction.

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • Regarding heating power and product condensing...

    I’m a big fan of going big on both. You almost can’t overdo product condensing. The single drawback is capital expense. Even that gets mitigated by lower water usage/cooling eventually tho.

    As for heat I kinda like being in the 100-120watt per liter range for fast heat ups between 45-70 minutes. With electric you have to add more elements as going with higher watt density has its issues.

    On reflux you do need to size the condensor properly and precisely control AND monitor flow rates.

    A weird side note I was just thinking of on a related topic. The discussion about product cooling temperature. I think the safe level of take off is relative to ambient humidity. With more humidity and ambient temps I feel like it’s safe to take off at higher temps like 26-35c. With dryer climates I think it’s would be prudent to cool the product down to a temp where it’s not easily off-gassing creating flammable vapor at those temps and humidity.

    That never occurred to me before...

  • @Fiji_Spirits Wow, that's a ton of power. I certainly wouldn't mind putting 50kW into our strip (1hr heat-up, 1-2hr strip), if we can make the elements work; our nice ULWD Watlow elements are 5kW each so we may be limited by boiler dimensions. Would definitely need to upsize the PC to 6-8"" for that, with a total length around 1.5m.

    Interesting thought on the ambient conditions, not sure I entirely agree on the humidity point. I need to brush up on my vapour dynamics, but my admittedly rusty understanding of Dalton, Henry, etc. says that H2O and ethanol vapour pressures should act mostly independently of each other; "dry" air evaporates water into it more readily than humid air, but all air is "dry" in terms of ethanol.

    Even so, always a good idea to keep output temps low. This is one of the thoughts behind the 2-stage PC setup, as we can condense and drop pretty efficiently to ~50C on water, then down to ~20C on glycol.

    @punkin True, the clamps etc. will shift costs a bit, if not a huge amount overall. If we incline our stripping lyne arm upward we can get that extra passive reflux regardless of diameter; maybe that's the smart move to give us extra condenser height & reflux at little cost. We've got 4.85m of height to work with so may as well use it.

  • edited February 25

    @gravbp said: 51kW on the strip is pretty angry, I can see how you'd overwhelm some cooling there. How long is that 6" you overcooked?

    The 6" is 48" long. The 12" is 52" long.

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  • Thanks @jbierling ! Are you packing that big reducer above the condenser with something to spread out the vapour flow?

  • Yes, there are stainless scrubbies in that 12-3" reducer. There is also a 3" condenser above the 12" in case I want to heat tap water. You can see the main recirculation tank (2400 gallons) for the condensers in the background.

  • I wonder if 1000l is too big for direct electrical heat. Maybe a Bain Marie or steam would be in order?

    As for humidity. My thought is that the water in the air means that any ethanol in the air can’t reach volatile levels as easily. Since ethanol doesn’t displace the water it’s just adds to total moisture and would also bind with water making it less volitile.

    That’s kind of my to thought. My experience in high humidity conditions would seem to bear that out. I could be way wrong tho. Who knows.

  • Yeah, definitely getting toward some limits on direct electric, but we're pretty tight on space so it's the easiest for us by far. Steam is out due to bureaucracy and layout, unfortunately; bain marie is workable but would still require a bunch of higher watt density elements and would increase boiler costs a lot. Plus the extra belly diameter means we're probably better off just squashing the still into a wider single-wall to allow for longer ULWD elements.

    Just want to thank everyone for all the input here, it's been a huge help! Will undoubtedly have more questions as we start configuring our columns and sensors, but that's a great starting point. Cheers!

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