10mm riser / outlet hole with bigger 15mm condenser

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Asos21
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10mm riser / outlet hole with bigger 15mm condenser

Post by Asos21 »

Just a hypothetical question for now but I'm very curious.

Let's say you have a 50l pot. And the 50l pot has a 10mm bulkhead in the top of the lid. The 10mm bulkhead has a short 6 inch piece of 10mm copper pipe attached. That 10mm copper pipe then has a 10mm to 15mm reducer which connects up directly to a 15mm condenser with a 28mm water jacket. The water jacket length would be 30 to 40 inches long.

How would this work out?

Basically my question is what would happen if you had a smaller output pipe from the boiler and a larger condenser tubing! 10mm outlet hole from boiler leading up to 15mm condenser tubing.

If it makes any difference the still would be running 2-3kw of power via an internal element.
NormandieStill
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Re: 10mm riser / outlet hole with bigger 15mm condenser

Post by NormandieStill »

I think your vapour speed is going to be extremely high or your throughput is going to be extremely slow.

My condensor is a 28 over 16mm liebig (so basically the same as what you're proposing), but it's sat on a 30l keg with a 2" triclamp on the top. And it's 2" all the way to the reducers that take it down into the liebig. In general, vapour speed and consequently production rate depends on the cross-sectional area of the riser. So going from 2" to 3" basically doubles your maximum take-off (Assuming boiler power is raised to match). I run 3kW and max out my 78cm liebig. I'm not sure what would happen if I started pushing more power into it (assuming I had a different condenser that could handle it).

10mm is basically 1/10th of the area of 2" so based on that, 3kW will likely be overkill.

If you're looking at building a 50l pot still, put a decent sized opening on it. A 2" tri-clamp bulkhead is not a luxury and now you'll have options available.
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Sporacle
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Re: 10mm riser / outlet hole with bigger 15mm condenser

Post by Sporacle »

+1 with Normandie, 10mm is very small. I have a 50L with a 2 inch bulkhead and 4000w I can strip at over 8L an hour, have to slow down a bit with rum washes, spirit run at a bit below 2 an hour and can reflux at 1 an hour, I have a inch over half liebig that is 900 long and 4000w is pretty close to Max, I do only use a low flow recirc pump though. I would suggest 2 inch as a minimum, it will allow a more options further down the track
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Asos21
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Re: 10mm riser / outlet hole with bigger 15mm condenser

Post by Asos21 »

Thanks guys! Again not planning on doing this as I already have a build.

Was just curious what would happen if the boiler had a small connecting pipe opening out into a standard sized condenser.

It was a route that initially I was going to take hence the curiosity.
LD50
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Re: 10mm riser / outlet hole with bigger 15mm condenser

Post by LD50 »

Just a data point, I have a mail-order 15 litre pressure-cooker style still I use for stripping only.
It has a 6mm (yes, less than 1/4 inch!) short riser into a spiral-in-a-fat-tube condenser (I forget the name for those right now it's early morning here)
It works fine, no worries. Far from optimal and if I had a 1-and-a-half or 2 inch triclamp flange adaptor fitting I'd drill that into the lid.

But I work with what I have and it's OK. I could run a standard UK mains-grid domestic gas hob close to 100% output when stripping with sufficient water flow, maybe 1 litre of headspace OR a low-foam. It was little happier at 75% output.

The condensor product outflow is 7mm ID, fed from that riser at 6mm ID.
Cooling water input/output hoses are 6mm ID. The condensor is designed or mains faucet/tap feed, not recirulating ambient in a bucket-style water.
Full gas hob power requires significant flow from a mains-fed faucet/tap flow but the stripping run product still comes out ambient.

Because I degass and clear well if I'm filling it up to the 15l max volume, puking doesn't happen (on sugar washes). Brandewyn I leave a litre or so headroom and run slower, but have never had a puke.

Bear in mind, this is for stripping only, where the main intention is to go kinda fast to make the volumes more manageable. But it goes to show that under the right conditions, very small tubing can work OK.

(pot stilling neutral vodkas - all sugar washes, 2 passes if I'm in a hurry, 3 passes for a quality almost tastless drink)

To answer your original question- It will work. No inherent problems matching a larger condensor to a smaller vapour tube (provided you have the couplings available haha)

I think if you had a 15mm inflow and a 10mm condensor, it would still work OK and in my world, that clopse to my normal practice (European-style sugar washing from 15% ABV 25l batches in a 15l still pot). Yep, vapour speeds would be very fast so a 50 litre wash through that sort of arrangement would be tedious. But it could be done and with the right amount of power and time it will definitely work.

A 10>15 or 15>10 condensor will not be a fast, time-efficient run though, for sure.

With current energy prices in Europe, you'd also have to bear in mind that heat loss in the system overall (heat loss being relatively constant over time, and mainly from an uninsulated pot) would make an arrangment like this more expensive to power for a 6 hour run than, say, something you could complete a run in 2 hours. But with cheap energy, free time and a good view, it'll work just fine. If you have a job, young family, limited space, distractions, etc then a slower vapour speed and larger feed would allow huge volumes to be processed easier though.

The reason I mention this: in the past, due to limited tubing resources where I was working for 6 months, I built a 22 over 15mm leibig, but my lyne arm into it was 28mm (inherited from the previous guy, who took his condensor away with him at changeover time) So I stepped down from 28mm vapour tube to 15mm (I'm talking in British-style ODs here) The lyne arm was about 60cm long on a 1M tall plain 28mm column (no plates or packing) and it ran just fine with a very powerful propane burner under the keg (a huge weld-preheater for thick steel pipes that gulped large gas tanks for breakfast). Strip runs went fast but used a LOT of cooling water. Spirit runs were done on a very low heat and the end result was great.
I suspect the 60cm of lyne arm provided some air cooling with the 28mm pipe and the 15mm condensor neck could handle it just fine. If there was no lyne arm length, maybe the vapour would be too hot entering a 15mm OD tube (about 13mm ID) with the burner on high.

My understanding is the first few cm of product condensor vapour tube cool the vapour charge and condense it (whereupon the expansive volume shrinks considerably as it condenses to a hot liquid) and the rest of the condensor length cools the liquid product towards ambient. With this is mind, I wondered if a fat-neck condensor using mainly thinner tubing for the majority of the length (say 15mm product, with a 22mm water over it ) but a wider short length of cooled neck - flaring to 28mm at the input end) would work well, but I've never had enough fittings of the right size lying around (meaning: easily stealable lol) to solder one up to test it. One for the condensor subforum maybe, one day in the future.
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