Advice on running 5 plate glass bubbler

[db1979]

Mine is 85 mm with 5 x 3/4" tubes that are filled with lose copper scrubbers. It responds in less than a minute, and with a 4 turn gate valve I have all the control I need within about half a turn from full reflux to stripping. I've never actually timed it's response time though, but it feels like a lot less than a minute. I should have a go at timing it next run.

I think there's been a trend on here for people to go for longer and longer RCs. And I think that trend coupled with a desire to run by overpowering the RC and or running a fast take-off rate has caused many to have problems.

Plated stills need to be balanced in terms of power, cooling flow, cooling temp, downcomer efficiency, column width and wash type. Add in a packed section and you're bound to have trouble if the rest aren't balanced. But ultimately I think you won't want a long RC. Warm cooling water should just need more water flow.

Additionally, my sieve plates can be run off as low as 1200 W (I think about 900 W saw it really misbehave) and still function but with far less vigorous bubbling. If I get the water flow balanced at this low power I can still get production but at a much slower speed. And less power means less reflux which also means lower quality product.

Take home messages: learn your still by keeping things simple to start with (no packed section), change one thing at a time and follow mac's instructions for running before experimenting with overpowering the RC. If you have no problems without a packed section, then the same run with a packed section and you come across problems, you know it's caused by the packed section.

[Amberale]

:text-+1:

Currently my power situation at home won’t give me 2 x 2400W so have been running mine on 1 x 2400W element... sloooooooooo as! But it works.

I also have a 500mm packed section but don’t have your issues... I think I did (a long time ago) - Heath talked me thru possibilities of ‘why’ turned out I stuffed a whole kilo of coppermesh in there as well as 15-20 SS scrubbers...
Waaay too dense!
So, we took the copper out and wound out 3 rolls the were loose but fitted tightly into the 4” tube. To clarify, we made 3 coils out of 1Kg copper mesh roll.
Now I use 1 of those in the top and one in the bottom and loosely fill the space in between with SS scrubbers (10-15 I think).
Problem solved.

I think this is my main issue.
I tried more power to offset the cold water issue but I have 1kg of copper wrapped in two cylenders top and bottom of my packed section with 11 ss scrubbers keeping them apart.
When I have run with 1 2400w I have had more success but more fiddling trying to get the low water flow adjusted.
Now I have a needle valve with a visual indication of water flow it should be easier.
I’m going to take 100g or so off each roll of copper and see how that goes.

I did have a 100mm RC but it had some sealing issues and was replaced with a 150mm one.
I was having a senior moment and comparing packed section length with RC. :doh:

[Amberale]

Yep it's on 75mm, check my glass duck build thread for more info.

I think you have way too much power for a 4" there. I'm guessing your packed section is flooding? I wouldn't think you'd need more than 3000w max, you should be able to run it on 2400w.

I think you’re right.
I was just trying to outsmart the very low water flow due to very cold water.
I might try to run my cooling water through a pipe in a bucket filled with the outflowing water to preheat it.
I’ll try to get everything else working first before introducing another variable.

Thanks and sorry for the thread steal

[Andrew]

I did have a 100mm RC but it had some sealing issues and was replaced with a 150mm:

Just to correct this statement .
You had an original 150mm that we replaced with a new 200mm :handgestures-thumbupleft:

[Amberale]

I did have a 100mm RC but it had some sealing issues and was replaced with a 150mm:

Just to correct this statement .
You had an original 150mm that we replaced with a new 200mm :handgestures-thumbupleft:

Bloody “senior moments” blocking the queue at the moment.
Sorry, family health issues are screwing with my mind and taking up lots of time at the moment.

I just thought 75mm seemed a lot smaller than what is on my riser( I know, size isn’t important, it just changes how you have to use it)

I just need some time to do some more brews and runs on the beastie to get it sorted out nd I don’t have that luxury at the moment.
Thanks Andrew, not complaining about the service, it’s been great.

[bigadz]

How many watts you throwing at it? Keep in mind there is a second way you can run these...blast past the rc using watts... find out how many watts the rc will hold back. Then with help of a voltage controller increase power beyond what the rc will hold back and run by output volume and smell taste.. not sure of your background but if you have your nose and tounge dialled in you should be able to blast past rc and use nose and taste. There is no subsitute for cuts in small amount airing then blending but once nose and tounge are tuned in you can do a pretty good job of tasting smelling straight off still(still collect in small amounts and do cuts) :-B

My background is IT! Both my Boilers have 2 x 2400w, use them both for heat up, then knock one out and maintain that throughout the run. When I run with 5 plates and 500mm packed section filled with copper, I have no probs knocking all of that down with my RC running at Max. However I can set the RC to Max and if I run 4 plates with no packed section, the RC can't knock it down at first, but then it catches up and drops back? It happened running wine twice and have just started searching about vapour speed.

RC is 200mm with 9 18mm pipes.

[bigadz]

I’m currently running a glassed like yours (tho only 4 plates), my packed section is 500mm and I use copper and SS mesh in there. To date I’ve always stripped first in pot still mode (because I do 150L washes to collect 50-75L low wines), then I do a spirit run with the full monty as you have describes at the beginning (I reflux for the full hour because I feel it gives me a cleaner product)... but I pull the power of the top element and just run one element, and ALWAYS do cuts!

My next purchase is a power controller (as bluc said above) so I can keep both element’s in the game and overpower my RC (300mm - But I live in the north where it’s far-quin hot 8-9 months of the year) as it should give me better control over the whole run, not just for neutral but also for whisky, and perhaps some Rum (not my strength!).
This will allow me to not have to worry about water flow...

I haven't tried overpowering the RC yet might be something for my next run!

I've been really keen to learn the best way to run my gear and the hobby bug has bitten me hard.

I always do cuts, air them and then try them.

I've now done a few runs, a couple of wines into grappa/brandy, tpw, ffv and my still has responded differently each time.

I've got a power controller for one of the elements so perhaps I can try overpowering above 2400w.

[Onlyalittlebitdodge]

Any adjustment to my water flow can take approx 5 minutes to settle, and I have seen it take as much as 15 minutes. Consider the size of your RC and how long it will take for metals to change to the different temperature, then allow even more time because stainless is not the best conductor. In any case you have a lot of knockdown power using a 4" RC + 4" x 200mm packed section with enough copper and stainless to fix the Bolivian economy.

My issue is sort of the opposite... I'm using 4 x 4" bubble plates with 2" x 200mm packed section with approx 2 x 200g copper scrubbers and 2" x 150mm RC, and I cannot stop offtake with the RC at max. (If I drop the boiler temp too low the plates load but don't bubble until the packed section is completely full and it ejects several litres in one big spurt). I hadn't thought of increasing the packing to achieve greater cooling, until reading this thread. I run one 2400W element, start offtake at around 35% and finish around 90% at approx 1.5 - 2lph.

Your rotameter is oversized, get a smaller one. All that pulldown power needs to be controlled at the lower end. Might pay to determine minimum flow rate to achieve zero offtake so you know the maximum flow rate you want your rotameter to measure.
Invest $42.95 in a temperature controller. You likely don't need all that 2400W.
A rough calculation of the approximate volume of your packed section with guess values to allow for area taken by scrubbers gives roughly 6 litres. Probably enough to flood your plates during cooling :)
If you're airing your cuts, are you really that concerned about achieving 95% ABV? Just a thought, are you reading the upper or lower meniscus?

[bigadz]

Any adjustment to my water flow can take approx 5 minutes to settle, and I have seen it take as much as 15 minutes. Consider the size of your RC and how long it will take for metals to change to the different temperature, then allow even more time because stainless is not the best conductor. In any case you have a lot of knockdown power using a 4" RC + 4" x 200mm packed section with enough copper and stainless to fix the Bolivian economy.

My issue is sort of the opposite... I'm using 4 x 4" bubble plates with 2" x 200mm packed section with approx 2 x 200g copper scrubbers and 2" x 150mm RC, and I cannot stop offtake with the RC at max. (If I drop the boiler temp too low the plates load but don't bubble until the packed section is completely full and it ejects several litres in one big spurt). I hadn't thought of increasing the packing to achieve greater cooling, until reading this thread. I run one 2400W element, start offtake at around 35% and finish around 90% at approx 1.5 - 2lph.

Your rotameter is oversized, get a smaller one. All that pulldown power needs to be controlled at the lower end. Might pay to determine minimum flow rate to achieve zero offtake so you know the maximum flow rate you want your rotameter to measure.
Invest $42.95 in a temperature controller. You likely don't need all that 2400W.
A rough calculation of the approximate volume of your packed section with guess values to allow for area taken by scrubbers gives roughly 6 litres. Probably enough to flood your plates during cooling :)
If you're airing your cuts, are you really that concerned about achieving 95% ABV? Just a thought, are you reading the upper or lower meniscus?

This is an awesome post with lots of details, thanks heaps!

So a couple of things that may help to make sense of it all:
- Taken notes of the rotameter and have ordered a smaller one
- I have a voltage controller for one of my elements, is that what you mean?
- My 500mm packed section is a 500g roll of copper, 10 copper scrubbers and then another 500g roll of copper
- I'm reading from what I believe to be the upper meniscus, however it's more to ensure I'm getting the most from my still, I do let them air and couldn't be tossed at the end of it all as it gets watered down to drinking strength
- I mentioned an issue with running wash/wine and having difficulties at the start of the run preventing off-take. The RC fills with cold water (and the last few runs have been on bloody cold days!) the element sits at 2400W and the wash/wine starts loading the plates, then I hear a gurgling, squeaking sound from the RC, temp on thermometer goes up suggesting it's passing vapour, and then i get a drop or so a minute. I haven't had this issue running 40% stripped gear.

I know this thread has sort of morphed a bit but the conversation is really helping me a lot!

[PeterC]

On my strip runs I regularly get a short period at the start of some reflux happening with vapours going past the RC, a brief temperature spike and a few drops coming out. These are some heads and I can smell acetone and other materials. After this it settles down and I full reflux for awhile then I collect heads slowly about 300-400 ml in a 50L wash. I generally throw this out. Obviously this doesn’t happen again on my spirit runs.

[db1979]

My issue is sort of the opposite... I'm using 4 x 4" bubble plates with 2" x 200mm packed section with approx 2 x 200g copper scrubbers and 2" x 150mm RC, and I cannot stop offtake with the RC at max. (If I drop the boiler temp too low the plates load but don't bubble until the packed section is completely full and it ejects several litres in one big spurt). I hadn't thought of increasing the packing to achieve greater cooling, until reading this thread. I run one 2400W element, start offtake at around 35% and finish around 90% at approx 1.5 - 2lph.

I think your 2" sections will be the cause of your troubles. Vapour speeds up in narrower sections. The vapour speed through your RC would make it very easy for the vapour to bypass it.

I'm probably wrong seeing as I've never used a packed section but it sounds like your packed section gets flooded because too much pressure from upcoming vapour is stopping it from coming down again to fill your plates. If this is the case it'd be caused by fast vapour speed due to the smaller diameter tube.

I have a 2" 4 plate bubbler that I used to run and it would only work nicely on about 900 W. 2400 W on a 2" packed section I think is too much. The 2" RC could probably work with 2400 W if it was longer.

[db1979]

- I mentioned an issue with running wash/wine and having difficulties at the start of the run preventing off-take. The RC fills with cold water (and the last few runs have been on bloody cold days!) the element sits at 2400W and the wash/wine starts loading the plates, then I hear a gurgling, squeaking sound from the RC, temp on thermometer goes up suggesting it's passing vapour, and then i get a drop or so a minute. I haven't had this issue running 40% stripped gear.

The sound you're hearing is probably the degassing of the cooling water in the RC. As the water heats up the air dissolved in the water becomes far less soluble and bubbles, this makes a squeaking sound in my RC. I've got 20 mm clear plastic tubing on my RC inlet and outlet and I can see the bubbles leaving the RC as soon as this happens. Also make sure your RC cooling outlet is the higher most otherwise air bubbles get trapped in the RC and it fills up with air, making it less and less efficient.

Read the lower meniscus only. There should be a flat section of product before it spills over the edge of your parrot, this is level with the bottom of the meniscus and is your best bet for reading your alcometer. As with any measurement, there will be errors.

[woodduck]

I'm with db here, 2" rc that long on a 4" bubbler will struggle I recon. The packing will only cause excessive reflux while it is cool, once it's up to temp the reflux all though it is there it shouldn't cause any problems. My guess is that the 4" plates are feeding too much vapour into the 2" packed section and causing flooding.

Also like db said make sure your water is going in the bottom of your rc otherwise it will more than likely be draining out the bottom and have air gaps that will cause poor cooling. You want the rc to be full of water.