Flooding bubble cap plates

[Royalwulf]

Hi, I have a home made still, 50L keg, 3" x 4 bubble cap plates, 3" packed column above that, packed with SS scrubbers + copper mesh and a 3" dephlegmator. I have 2 heaters, 2.2kw and 5 kw. I use a voltage controller. I have used the still successfully several times since building but I haven't used it for quite a while and I think I have forgotten how to. Yesterday I tried to run a kale wash. I turn the 5kw heater off as it starts to reflux and run on the 2.2kw. The issue I had was flooding while trying to get full reflux and fores etc. I turned down the power thinking that was the issue.After a lot of experimenting I got it to run without flooding at about 45% power. Usually I can run it at 80% to 100%. Fores and heads ran ok but I had issues getting enough power to run hearts. What have I done wrong? cheers

[TheRealMrMessy]

The setup sounds about right with packing above plates etc. and you say you had no problem running closer to the 100% before. Heat on the 5kw and run on the 2200w with power control... all good practice. It's all a balance of vapour up vs liquid down... What type of plates are you using? Downcomers all flowing properly?

On the technique, if you are just continually adding power and flooding, try decreasing your reflux cooling gradually instead of increasing power, just a bit and wait a min or two before adjusting again. It takes bugger all water on the RC even for me with my 4" at 3000w or so to have a good reflux ratio, and I do need a fine needle valve to control it. Once you hit that fine balance of just enough cooling (and the reflux condenser has warmed up a bit), when you add power you should soon push some product past the condenser, slowly adding power as your run progresses through hearts to maintain the offtake rate. If you flood again, pull back on the cooling a bit more.

[Royalwulf]

The setup sounds about right with packing above plates etc. and you say you had no problem running closer to the 100% before. Heat on the 5kw and run on the 2200w with power control... all good practice. It's all a balance of vapour up vs liquid down... What type of plates are you using? Downcomers all flowing properly?

On the technique, if you are just continually adding power and flooding, try decreasing your reflux cooling gradually instead of increasing power, just a bit and wait a min or two before adjusting again. It takes bugger all water on the RC even for me with my 4" at 3000w or so to have a good reflux ratio, and I do need a fine needle valve to control it. Once you hit that fine balance of just enough cooling (and the reflux condenser has warmed up a bit), when you add power you should soon push some product past the condenser, slowly adding power as your run progresses through hearts to maintain the offtake rate. If you flood again, pull back on the cooling a bit more.

Thanks.they are Chinese bubble cap plates, the downcomers were working as good as they used to if I remember correctly, they were working anyway. I got the power to 48% any higher it would flood, then I decreased cooling as you suggest. This got me through the fores and heads but I couldn't increase it for the hearts as there was no water going through reflux condenser so no reflux.

What puzzles me is this used to work fine so why not now?

[The Stig]

Cooling water too cold maybe

[Royalwulf]

Cooling water too cold maybe

ok, could be, it was -1 to start with , but warmed up to 8 during the day

[TheRealMrMessy]

That’ll do it, can’t get the water flow low enough. See if you can get a really fine needle valve for the reflux condenser and give it another whirl.

[Royalwulf]

That’ll do it, can’t get the water flow low enough. See if you can get a really fine needle valve for the reflux condenser and give it another whirl.

would that cause flooding? I would have thought it needed more power not less. i can see it would give me differculties getting greater flow for hearts but not flooding.

[TheRealMrMessy]

It's a vapour limit thing. Don't stress about the power level as such - it is what it needs to be to get you started and depends to an extent on the final gravity and abv of the wash.

Where you describe in your process upping power until the point of almost flooding then reducing water flow, try instead to get a comfortable reflux rate going with some headroom left on power and dial back the cooling first.

1. Power on up to temp.
2. Drop to your controlled 2200w.
3. Find your max power level for flooding. Dial back at least 200, 250w from that.
4. Adjust cooling down gradually (takes several minutes to have an effect, be patient!).
5. Once a drip or two coming over, you have a choice - ease cooling down a tiny bit more or increase power (since you are balanced well under your flooding point).

I dial cooling down while taking fores and heads, then increase power into hearts and through the run as the abv drops, though I've also never had to balance so close to flooding either.

If you can't get those few drops started, probably as suggested your cooling water is just too cold for the equipment combination to work with - hence my suggestion for a needle valve so you can slow it way way down to almost zero!

[Mr.Roughnutz]

not having run bubblers but if ur geting reflux with no watter in ur deflag then why question is how much pasive reflux are u geting from ur packed section?

[TheRealMrMessy]

not having run bubblers but if ur geting reflux with no watter in ur deflag then why question is how much pasive reflux are u geting from ur packed section?

Not quite what is happening bloke. I'm sure if the deflag water is off the reflux will stop once the deflag heats up (might take 15min but it'll get there!). Problem is its just a fancy looking pot still then.

Because the cooling water is so cold the vapour can't warm it up enough to overcoming the knock-down cooling. While adding power does add heat through more vapour flow up, its hitting the next barrier = the vapour limit of the column and plates and flooding them while still not producing. My 4" setup running 4 plates and standing over 2m tall, running at 2200w uses around 30 litres an hour for the deflag, maybe 35 if running 3000-3500w depending what I'm doing, and my tap water temp here is sitting around 26c. Royalwulf's 3" setup running give or take 1200w with basically zero degree cooling water in the deflag is going to struggle unless the water flow is able to be controlled to a very low flow rate.

[RuddyCrazy]

For a start I don't use elements as that little BD burner I made does everything I want :laughing-rolling: never had a problem with flooding as you guy's put it. Now I run my bubbler until the PC condensers the fores take a good 200ml fores cut then throw it back into reflux until all the plates are fully loaded which also gives the site glass's a good clean :laughing-rolling: while totally compressing the heads.

In winter my cooling water is that cold I get huffing out the spout of water vapour :scared-eek: and yes I do use a needle valve for my RC, now at 25 past clock wise the RC is totally closed and I usually set it at 15 past for the run so that little cold water is enough to control my still.