Problems running VM

[bunny]

Thanks to everyone who has input and made suggestions!

We go again.
OK, I'll go with you
I removed the top half of the column, leaving the lower 1.5m section. This is filled with 125cm of SPP with a scrubber top and bottom of the SPP and a 10cm gap from the top of the packing to the 1/2" vapour take-off valve above it. Replumbed it and ran again. This sounds good

Still to do is: column insulation and a drip guard above the temperature probe that sits opposite the vapour take-off valve.
Insulate the column and as much of the boiler you can before you run again. All of your temp numbers appear to be distorted. If the boiler is actually boiling with 35% low wines, the temp should be about 85*C, not 78*C. The probe near the take-off should be about 78*+ when product is being collected. Could be getting "rained on" by distillate.
Filled the pot with 50 litres of 30% ABV barley wash, left the vapour take-off valve open (no equilibrium stage) and warmed it all up.

Good news: We have distillate exiting the column and filling the parrot
I hate parrots!
So then I ran a series of tests with the vapour take-off valve at different settings to measure flow rate and also worked out the maximum gas setting I could use before the draining liquid was forced back up the column, potentially flooding it. I will do a separate test to calculate this setting in kWh of gas.

Most of your numbers at best can point you toward better results in the future. Since you did not get through the fores and heads you have zero hearts to taste at this time. I would bet they would be very clean. Were the ABVs you listed temp corrected?
During the test, I collected just over a litre of distillate in total, so never got past the heads stage.

I have pulled together all the data in this spreadsheet. Hope it makes sense if interested.
Test Feb 1, 2023.xlsx
Sadly, most of your collection rate numbers are heartbreaking for your purpose. The only way to improve these rates is by enlarging the take-off 1/2" tube to possibly 1" or more. SMF, or maybe Hebden might have some numbers from their relatively recent experiences.
With the vapour port open settings, I had these flow rates:
Initially open full: 750ml per hour
Closed for gas input testing and then reopened by half: 424ml per hour
Opened to 3/4: 679ml per hour
Opened fully: 923ml per hour

Just a reminder that the boiler is 250 litres and the column is 64mm internal diameter.

Does a litre an hour seem about right? That makes for a very long run!
No. My guess you should get at least 2L extremely clean neutral with a 2 1/2" column, maybe a lot more.?
One thing I could not rationalise is that the temperature below the reflux condenser started dropping when the vapour take-off valve was closed by half, from initially being fully open. Temperature started rising again when the vapour valve was being opened again.
I'll go along with Mars and Greggn here.
The pot temperature is measured in the lid and with the boiler only being partially filled, the analogue temperature probe was about 80cm above the liquid level. Does the analog thermometer have a short thermowell? If so, your freezing lid is transferring a far amount of cold into the thermometer. Can you hear the boiler boiling when it's up to temp?

The level of coolant needed to keep the reflux condenser stable was about 40 seconds per litre. Mains water here is about 10°C. That's a lot of water, approx 99 litres for 1 litre of distillate per hour. Water currently costs here 32 Pence per hectolitre.
What is the outlet temp of your condenser?
Now that we have some output, my next step will be to run again with 160 litres of 30% ABV wash and cut the distillate. I am expecting approximately the cuts to work as follows. Do they sound about right?
image.png
Where did you get that chart? I can only speak for myself. I collect 1500ml of fores and heads(13.4%) from a 28L x 40%ABV low wines batch from my usual sugar wash. I then collect 6L of hearts (54%). Then I collect 2 -2 1/2 L of the next stuff to toss into the next run. I start with 3 12g ferments, (36g total) and end up with approximately 4.4% hearts
Final question - how long should I expect the equilibrium stage to take? I had worked on the basis of 2 hours but with 2 hours warmup of the still charge, that's a big chunk of the day gone before collection starts.
I'm following the lead of others here. Since I have a relatively tall column filled with spp and it takes a long time to heat up, which it does fairly uniformly. I start up immediately drawing at 200ml/hr. For me, this is a seven or eight hour process to reach 1500ml total. I then do my last judgement for the day taking the next 5ml off the spout and mix with 25ml distilled water. Sometimes I re-do the final judgement more than once. Then shut down and restart in the morning.
Thanks again for your input.
Matt

[kimbodious]

Matt it is not too late for you to read this great resource by kiwistiller viewtopic.php?t=15508

[bunny]

Thanks to everyone who has input and made suggestions!

We go again.
OK, I'll go with you
I removed the top half of the column, leaving the lower 1.5m section. This is filled with 125cm of SPP with a scrubber top and bottom of the SPP and a 10cm gap from the top of the packing to the 1/2" vapour take-off valve above it. Replumbed it and ran again. This sounds good

Still to do is: column insulation and a drip guard above the temperature probe that sits opposite the vapour take-off valve.
Insulate the column and as much of the boiler you can before you run again. All of your temp numbers appear to be distorted. If the boiler is actually boiling with 35% low wines, the temp should be about 85*C, not 78*C. The probe near the take-off should be about 78*+ when product is being collected. Could be getting "rained on" by distillate.
Filled the pot with 50 litres of 30% ABV barley wash, left the vapour take-off valve open (no equilibrium stage) and warmed it all up.

Good news: We have distillate exiting the column and filling the parrot
I hate parrots!
So then I ran a series of tests with the vapour take-off valve at different settings to measure flow rate and also worked out the maximum gas setting I could use before the draining liquid was forced back up the column, potentially flooding it. I will do a separate test to calculate this setting in kWh of gas.

Most of your numbers at best can point you toward better results in the future. Since you did not get through the fores and heads you have zero hearts to taste at this time. I would bet they would be very clean. Were the ABVs you listed temp corrected?
During the test, I collected just over a litre of distillate in total, so never got past the heads stage.

I have pulled together all the data in this spreadsheet. Hope it makes sense if interested.
Test Feb 1, 2023.xlsx
Sadly, most of your collection rate numbers are heartbreaking for your purpose. The only way to improve these rates is by enlarging the take-off 1/2" tube to possibly 1" or more. SMF, or maybe Hebden might have some numbers from their relatively recent experiences.
With the vapour port open settings, I had these flow rates:
Initially open full: 750ml per hour
Closed for gas input testing and then reopened by half: 424ml per hour
Opened to 3/4: 679ml per hour
Opened fully: 923ml per hour

Just a reminder that the boiler is 250 litres and the column is 64mm internal diameter.

Does a litre an hour seem about right? That makes for a very long run!
No. My guess you should get at least 2L extremely clean neutral with a 2 1/2" column, maybe a lot more.?
One thing I could not rationalise is that the temperature below the reflux condenser started dropping when the vapour take-off valve was closed by half, from initially being fully open. Temperature started rising again when the vapour valve was being opened again.
I'll go along with Mars and Greggn here.
The pot temperature is measured in the lid and with the boiler only being partially filled, the analogue temperature probe was about 80cm above the liquid level. Does the analog thermometer have a short thermowell? If so, your freezing lid is transferring a far amount of cold into the thermometer.
(Well, actually, it would be the other way around: The lid would be sucking the heat out of the thermowell)
Can you hear the boiler boiling when it's up to temp?

The level of coolant needed to keep the reflux condenser stable was about 40 seconds per litre. Mains water here is about 10°C. That's a lot of water, approx 99 litres for 1 litre of distillate per hour. Water currently costs here 32 Pence per hectolitre.
What is the outlet temp of your condenser?
Now that we have some output, my next step will be to run again with 160 litres of 30% ABV wash and cut the distillate. I am expecting approximately the cuts to work as follows. Do they sound about right?
image.png
Where did you get that chart? I can only speak for myself. I collect 1500ml of fores and heads(13.4%) from a 28L x 40%ABV low wines batch from my usual sugar wash. I then collect 6L of hearts (54%). Then I collect 2 -2 1/2 L of the next stuff to toss into the next run. I start with 3 12g ferments, (36g total) and end up with approximately 4.4% hearts
Final question - how long should I expect the equilibrium stage to take? I had worked on the basis of 2 hours but with 2 hours warmup of the still charge, that's a big chunk of the day gone before collection starts.
I'm following the lead of others here. Since I have a relatively tall column filled with spp and it takes a long time to heat up, which it does fairly uniformly. I start up immediately drawing at 200ml/hr. For me, this is a seven or eight hour process to reach 1500ml total. I then do my last judgement for the day taking the next 5ml off the spout and mix with 25ml distilled water. Sometimes I re-do the final judgement more than once. Then shut down and restart in the morning.
Thanks again for your input.
Matt

[Matt64]

Matt it is not too late for you to read this great resource by kiwistiller viewtopic.php?t=15508

Very helpful for my next run - thanks for that

[Matt64]

I have pulled together all the data in this spreadsheet. Hope it makes sense if interested.
Test Feb 1, 2023.xlsx
Sadly, most of your collection rate numbers are heartbreaking for your purpose. The only way to improve these rates is by enlarging the take-off 1/2" tube to possibly 1" or more. SMF, or maybe Hebden might have some numbers from their relatively recent experiences.
With the vapour port open settings, I had these flow rates:
Initially open full: 750ml per hour
Closed for gas input testing and then reopened by half: 424ml per hour
Opened to 3/4: 679ml per hour
Opened fully: 923ml per hour

If I enlarge the take-off port to 1" or more, to increase the output rate (it is a bottle neck at the moment), presumably I need to maintain the same pipe diameter down to and through the condenser, until the distillate is liquid again?

Cheers,
Matt

[bunny]

I have pulled together all the data in this spreadsheet. Hope it makes sense if interested.
Test Feb 1, 2023.xlsx
Sadly, most of your collection rate numbers are heartbreaking for your purpose. The only way to improve these rates is by enlarging the take-off 1/2" tube to possibly 1" or more. SMF, or maybe Hebden might have some numbers from their relatively recent experiences.
With the vapour port open settings, I had these flow rates:
Initially open full: 750ml per hour
Closed for gas input testing and then reopened by half: 424ml per hour
Opened to 3/4: 679ml per hour
Opened fully: 923ml per hour

If I enlarge the take-off port to 1" or more, to increase the output rate (it is a bottle neck at the moment), presumably I need to maintain the same pipe diameter down to and through the condenser, until the distillate is liquid again?

Cheers,
Matt

I'm not remotely sure what you should do.
There was a time 10-12 years ago that your problem was heavily argued over on this forum.
I haven't been able to find the exact threads again, but I'm pretty sure they are after 2008.


EDIT: Here's two of many interesting threads that don't want to link at this time:

go to "Column Builds", Sun May 19, 2013 4:12pm, "please set me straight - VM build" (choppinlow)

"Research and Theory", Wed Aug 26, 2009 11:49am, "Measured product production in VM head" (DestructoMutt)





If you can find them I'm sure you will get a better understanding of the flow in a VM column.

[Sporacle]

If I enlarge the take-off port to 1" or more, to increase the output rate (it is a bottle neck at the moment), presumably I need to maintain the same pipe diameter down to and through the condenser, until the distillate is liquid again?

Hope I'm understanding correctly Matt.
You don't need the same size pipe diameter in your condesor as the rest of your set up.
My 2 inch modular ran with a inch over half inch liebig.
As long as it is able to condense the vapour and handle the flow rate a smaller diameter will be fine

[Matt64]

"Research and Theory", Wed Aug 26, 2009 11:49am, "Measured product production in VM head" (DestructoMutt)
viewtopic.php?t=11396

Thanks Bunny - reading through that thread and others seems inconclusive, as there are many views on both sides. I will have to do my own tests to work that one out.

If I enlarge the take-off port to 1" or more, to increase the output rate (it is a bottle neck at the moment), presumably I need to maintain the same pipe diameter down to and through the condenser, until the distillate is liquid again?

Hope I'm understanding correctly Matt.
You don't need the same size pipe diameter in your condesor as the rest of your set up.
My 2 inch modular ran with a inch over half inch liebig.
As long as it is able to condense the vapour and handle the flow rate a smaller diameter will be fine

Thanks Sporacle - what sort of distillate per hour output do you get from your 2" column and are you running neutral?

My column is 2.5" wide, so I am thinking that I will add a 1" takeoff valve connected to a 22mm pipe and then run this down to the existing 1/2" condenser to see how that affects take-off. Or should I go larger and add a 2" takeoff?

Slow output
I ran the column again with a larger volume of 30% ABV low wines and the slow output rate is hugely frustrating. I was getting output of 1 litre per 1 hour, extending to 1 litre per 1.5 hours later in the run, with the 1/2" valve wide open. This meant running over 3 days, which is totally impractical. And the time is dragged out further by needing to heat the boiler up again, although it was faster on days 2 and 3 due to the residual heat left in the liquid.

I have trawled the forum but haven't found anything definitive about expected max output of a 2.5" column for 96% ABV neutral. I would need to be hitting 2.5 to 3 litres an hour output for a 2.5" column to be feasible. Does anybody have experience as to how realistic that might be?

The other option is to ditch the 2.5" and move to a 4" packed column. That would give 2.5 times the column area, so could I expect that the output for 96% ABV neutral would be 2.5 times faster that for the 2.5" column - in theory.

At a 20:1 column height to diameter, a 4" column would need to be 2 metres high. That's not a problem and I have room to go higher.

Centering constrictor
At the moment I don't have a centering constrictor to direct the reflux away from the column walls but found this thread that describes it viewtopic.php?t=12386&start=30

Also, I see people using a “turbulator” to disrupt the vapour flow to improve the vapour split to the takeoff valve and increase output.

Insulation
I need to drastically improve the column insulation to improve efficiency. I can buy products like this but need to check its fire rating.
https://www.screwfix.com/p/ybs-thermawr ... -05m/9691p
Unless there is something more suitable?

Taste
I had another issue. The taste of the distillate was not clean. When I have run tests with a smaller test still in the past, the result was clean.

This wasn't, so I am trying to troubleshoot this. Some possibilities?
- The wash I used was resused barley wash that I have been using for testing. It was stripped a year ago and has been through the column still maybe 8 or 9 times and each time all the distillate was added back to the main batch. Perhaps it's possible for off flavours to be picked up during all this testing but I had hoped that the 1.25 metres of packing would clean it up.
- The distillate was coming off at 96% ABV but maybe I was not getting the separation that I intended and so the hearts were contaminated. Perhaps I was running the column too hard to try to get more output (it didn't make any difference).
- Maybe the stainless SPP is not creating the separation I was hoping for?
- Maybe adding a copper scrubber above the stainless SPP to introduce some more copper into the system. The boiler and column itself are copper but the SPP packing is all stainless.

I back-flush the column with water after every run but one thing I notice is that a black layer can quite quickly build up on the copper surface. A citric wash will remove it but could the presence of the black layer create flavour contamination?

I am trying to work this out as much as I can by myself but my experience with this type of set-up is limited and progress has been much slower than I would like, so I really appreciate all the input.

Matt

[Sporacle]

2 inch CCVM, a touch under a litre per hour around 95abv or a touch under.

[OtisT]

Slow output
.....
I have trawled the forum but haven't found anything definitive about expected max output of a 2.5" column for 96% ABV neutral. I would need to be hitting 2.5 to 3 litres an hour output for a 2.5" column to be feasible. Does anybody have experience as to how realistic that might be?

The other option is to ditch the 2.5" and move to a 4" packed column. That would give 2.5 times the column area, so could I expect that the output for 96% ABV neutral would be 2.5 times faster that for the 2.5" column - in theory.

At a 20:1 column height to diameter, a 4" column would need to be 2 metres high. That's not a problem and I have room to go higher.

Matt

In my experience you will need a larger diameter column in order to get a higher production rate and maintain quality. Since you are at 2.5” now and not even close to happy with your production rate, change to a 4” packed column and you should be able to get 3 lph or more at 95+%.

[Yummyrum]

I agree with Sporicle
My 2” pulls 95% from 40% low wines at a little under 1l/h .

If I open the valve more and collect faster, the AVB drops .
But I certainly can get the separation I’m happy with using this rig .

2.5” is not much bigger than 2” , so I believe the reslts you are getting a pretty much to be expected .
Sure , you could fit a larger outlet and valve , and this will increase your potential takeoff rate , but the ABV will drop .

I also agree with Otis.
If you want higher takeoff rate , and if you are commercial , you’re gunna need it , you need a bigger size column .

I have a 4” 2metre tall VM . The takeoff port and valve is 1.25” and its never fully open .
I can pull just over 3l/h but the ABV starts to fall below 95%.
I think 4” is more suited to the size of boiler and you are using .

But remember that you will need around 8kw potential power to get the most out of it and cooling requirements increase big time .

[Matt64]

I have a 4” 2metre tall VM . The takeoff port and valve is 1.25” and its never fully open .

Is that a packed column or plated and does the 2m height deliver a clean pure product? Is the take-off pipe 1.25" down through the condenser?

What wash volume are you running and how long in total does the run take, as the output rate will drop over the run.

I read somewhere that 4" is about the limit for packed.

Sounds like there is not much point in modifying the existing 2.5" column. Better to start again with a wider one.

I can rationalise the slow output and the fix to that seems clear. I was however thrown a bit by the taste of the hearts that came through off the last run. Testing on a smaller still previously (but with the same column) gave much better results.

Cheers,
Matt

[bluefish_dist]

1l/hr is about right for a 2”. A 3” should do 2l/hr and a 4” 4l/hr, then jumping to 6” you can get 8l/hr. Also taller is better. For a neutral with scrubbies, I would aim for a minimum of 6ft of packed. 8ft will be better. Yes, you can go bigger than 4” with packed, but how you arrange the packing does matter.

[Matt64]

1l/hr is about right for a 2”. A 3” should do 2l/hr and a 4” 4l/hr, then jumping to 6” you can get 8l/hr. Also taller is better. For a neutral with scrubbies, I would aim for a minimum of 6ft of packed. 8ft will be better. Yes, you can go bigger than 4” with packed, but how you arrange the packing does matter.

Thanks for the output numbers. Are you able to elaborate on "how you arrange the packing does matter" please?

Cheers,
Matt

[bluefish_dist]

Thanks for the output numbers. Are you able to elaborate on "how you arrange the packing does matter" please?

Cheers,
Matt

On a 2”, you can just stack scrubbies and fill the column. On the 6” I had to arrange each level, can’t just throw them in and expect good results. If I remember right it was one in the middle and then 5 or 6 around the outside, then stagger the next level so that the scrubbie is sitting over were the level below had two meet. On the 4”, I think it was 4 or 5 per level and staggered by 45 deg or so. Takes more time to put in all the packing, but it does make a difference. On the 6” I did a random fill and it would only hit 188-189 proof. Once I repacked it in an ordered manner, I could run 190.3-190.5.

[Matt64]

Thanks for the output numbers. Are you able to elaborate on "how you arrange the packing does matter" please?

Cheers,
Matt

On a 2”, you can just stack scrubbies and fill the column. On the 6” I had to arrange each level, can’t just throw them in and expect good results. If I remember right it was one in the middle and then 5 or 6 around the outside, then stagger the next level so that the scrubbie is sitting over were the level below had two meet. On the 4”, I think it was 4 or 5 per level and staggered by 45 deg or so. Takes more time to put in all the packing, but it does make a difference. On the 6” I did a random fill and it would only hit 188-189 proof. Once I repacked it in an ordered manner, I could run 190.3-190.5.

Ah, OK. I am using stainless SPP, so I am guessing that the column can simply be filled with this? Have you tried SPP in your columns? Not sure if there is a limit to column diameter with SPP?

Do you know of any numbers that show what kWh of power input are needed for 4" and 6"? I am using a gas burner which is rated at 14kWh but I haven't yet worked out what it is in reality from my heat up numbers.

[bluefish_dist]

Yes, just dump the spp in. I tried some member made spp and was never able to get it to work as well as scrubbies. Gave up due to the cost and wasn’t able to get better performance. Also tried structured packing which came as pucks. It’s hetp was rated very good, but again could not get it to run as well as scrubbies. Used marbles as well and still have them to use on a 4” column. Marbles hetp isn’t quite as good as scrubbies, about 5.5” vs 4” for scrubbies. That’s fine as I use only a short packed column instead of plates. For a neutral column, they were too heavy and expensive. 4” x 8 ft is a lot of marbles.

Power, 1500-1800w for 2”, 3000 ish for 3”, 6000 ish for 4, 12000 for 6” although I ran my 6” on 8000 as that’s all the power I had in that boiler.

[Matt64]

Yes, just dump the spp in. I tried some member made spp and was never able to get it to work as well as scrubbies. Gave up due to the cost and wasn’t able to get better performance. Also tried structured packing which came as pucks. It’s hetp was rated very good, but again could not get it to run as well as scrubbies. Used marbles as well and still have them to use on a 4” column. Marbles hetp isn’t quite as good as scrubbies, about 5.5” vs 4” for scrubbies. That’s fine as I use only a short packed column instead of plates. For a neutral column, they were too heavy and expensive. 4” x 8 ft is a lot of marbles.

Power, 1500-1800w for 2”, 3000 ish for 3”, 6000 ish for 4, 12000 for 6” although I ran my 6” on 8000 as that’s all the power I had in that boiler.

Thanks bluefish_dist

I calculate that I have >8000 but it's complicated by the fact that the copper boiler is not (yet) insulated, so I am losing a lot of heat, particularly while its so cold here in the UK.

A couple of issues have thrown me when testing. When I did my last test run, I was not getting a clean vodka product and I can't work out whether the 1.25cm height of spp is insufficient, or was it down to pushing too much heat into the column?

Also, when I have the column extension on, doubling the height of spp, I could not get any output at all, even though the top of the column was at temperature. The column wasn't insulated then and it was close to °C when I ran it. Could the lack of insulation be the issue that stopped vapour exiting?

[bluefish_dist]

I would guess your 1.25m is not enough height. It doesn’t take more than 2 kw for a 2” column. Less power should give a higher abv within reason. Also takeoff rate will drop as well. A true azeo or 190+ neutral is hard to get imho. You need a super efficient column. From what I have read by people who have been successful with spp, it has to be run in a semi flooded state to get a short hetp. I was never able to achieve this with spp. I quickly gave up on it and moved to larger diameter to get more output as it was cheaper and worked better.

[Yummyrum]

I have a 4” 2metre tall VM . The takeoff port and valve is 1.25” and its never fully open .

Is that a packed column or plated and does the 2m height deliver a clean pure product? Is the take-off pipe 1.25" down through the condenser?

What wash volume are you running and how long in total does the run take, as the output rate will drop over the run.

It is packed with ss scrubbers . I initially tried scoria and of different sizes but found scrubbers gave me better results . Also assembling and dismantling a column full of rock was getting too heavy for me .

Yes the takeoff , valve and 90° bend into the condenser is all 1.25”

I’ve always stripped first before using a reflux still and this was no exception . To be honest , I haven’t used it for a year or two now but from memory I was loading around 45-50 litres of low wines .
It was taking me about 7 or 8 hours with heatup .
Would keep around 13litres of hearts IIRC and yes it tasted fine , no off tastes at all .

[Yummyrum]

Sorry, I tell a lie .
I forgot I’d reduced it down to 3/4” and added a compression fitting when I needed the condenser for other duties .
I don't thing it matters a big deal that far from the column . Vapour flow may speed up as it goes inti the smaller pipe , it probably also starts to slow again as it hits the 1.25” at the start of the Shotty .

Also here is the takeoff module on the 4” .
I just unscrew the valve off the 2” head and attach it to the 4” . You can see part of the 2metre packed column behind it . It’s actually 2 x1 metre sections. I started with 1metre then added a second .

[Matt64]

My 2.5" column currently sits on top of an alembic still with a 2.5" dia fitting on top of the pot. If I go larger (4" or 6" column) I am probably going to have to sit the column to one side of the pot as I am not sure that the copper would take the weight of a 6" packed column 3m high.

Since the fitting on top of the alembic pot is 2.5", am I going to run into constriction issues, running a 2.5" pipe from the top of the pot into the base of a 6" column?

That 6" x 3m column has a volume of 59 litres, so it's going to take a lot of packing.

[Matt64]

It is packed with ss scrubbers . I initially tried scoria and of different sizes but found scrubbers gave me better results . Also assembling and dismantling a column full of rock was getting too heavy for me .

Are they winding scrubbers and woven scrubbers? I see that there are two kinds, see https://www.stainlesssteelscrubber.org/ ... ubber.html

The woven kind look to me like they could compress under the weight of a tallish column.

[bluefish_dist]

My 2.5" column currently sits on top of an alembic still with a 2.5" dia fitting on top of the pot. If I go larger (4" or 6" column) I am probably going to have to sit the column to one side of the pot as I am not sure that the copper would take the weight of a 6" packed column 3m high.

Since the fitting on top of the alembic pot is 2.5", am I going to run into constriction issues, running a 2.5" pipe from the top of the pot into the base of a 6" column?

That 6" x 3m column has a volume of 59 litres, so it's going to take a lot of packing.

A 6” x 3m column is huge for a home distiller. With a 25 gal still you will have a hard time even getting it to run right unless you only run low wines. I ran a 6” x 8’ over a 30 gallon still, but I fed it from a 120 gallon still that I used for stripping runs (Running commercial). For home use a 4” is plenty big, it will also run better if using scrubbies for packing. A 4” should pull 1 gal/hr at the start.

Offset columns need to be able to drain back to the boiler. Can be done by gravity or a pump.

[Yummyrum]

It is packed with ss scrubbers . I initially tried scoria and of different sizes but found scrubbers gave me better results . Also assembling and dismantling a column full of rock was getting too heavy for me .

Are they winding scrubbers and woven scrubbers? I see that there are two kinds, see https://www.stainlesssteelscrubber.org/ ... ubber.html

The woven kind look to me like they could compress under the weight of a tallish column.

I used the large winding scrubbers .They are about 4” so initially I just pushed them in similar to what I’d done with smaller ones on my 2” . However I discovered that if I teased them out first , and then packed them in , I got higher ABV and could run more power before flooding .

I believe Shadylane found the same thing .
I suspect that the area inside the coils is not utilised so it it becomes inefficient in the space . When teased out, there is more access for vapour and liquid to make contact .

[Matt64]

A 6” x 3m column is huge for a home distiller. With a 25 gal still you will have a hard time even getting it to run right unless you only run low wines. I ran a 6” x 8’ over a 30 gallon still, but I fed it from a 120 gallon still that I used for stripping runs (Running commercial). For home use a 4” is plenty big, it will also run better if using scrubbies for packing. A 4” should pull 1 gal/hr at the start.

Pot still is 250 litre. Will be running low wines only that is stripped in a separate still.

My main priority is high quality commercial vodka but at a fast enough output that it doesn't need to be run over two days. It takes 2 hours to heat the still up to temperature, so that is already a chunk out of the day.

[bluefish_dist]

My 6” on half that volume (120l) was a full day of running. If you are running 250l of low wines, you really need 8” or bigger. Pretty sure at 8” you will need to be plates or structured packing. For structured packing to work you will need a tall column, probably a minimum of 3 M. I found the hetp was a lot higher than the 4” of scrubbies.
. You will also need a lot of power to make an 8” go, 20kw. At that point, steam is probably the best choice and we are far beyond what any hobby distiller will ever use.

[Yummyrum]

Probably a daft Idea , but what about a bank of smaller stills .
A 50 litre keg with a 3” column pumps out over 2l/h of high. Quality and can be easily run in a day . Get 4 of these and you’d be making 10 L/H easily .
And they don’t need a 2 Story warehouse and a staircase to adjust .

[Salt Must Flow]

A decent 3" should get at least 3 lph. I get just a bit more, approx 3.25 lph at 2750W.

[Yummyrum]

A decent 3" should get at least 3 lph. I get just a bit more, approx 3.25 lph at 2750W.

Thats pretty decent SMF .I struggle to get much more than that in my 4” …… but I’m not using SPP

Also to add to my silly idea ,most have a 50litre keg boiling in under an hour . 4 x 50 litre kegs producing while Matts big 250litre job is still halfway through heatup …. Although I guess Matt could double his elements.

And more smaller stills can be added to as finances dictate .