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flyhigher87

Pulsing Still

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Hey guys hope all is well.

So I'm in the middle of a vodka run and my distillate is pulsing.  By this I mean, the distillate will completely stop for like 10-15 seconds and then all of a sudden open the flood gates for like 5 seconds.  This has only happened once before on a previous run.  Normally my still is pretty steady stream a little variation in flow rate but nothing this drastic.  My still is a small 50 gallon it has four plates and a large random packed section with copper scrubbers and raschig rings.  I am running a dephlag with little trickle of water through it to maintain 95% abv.  

So Why is my distillate flow rate so crazy today??

 

thank you.

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Sounds like a back pressure issue. Did this just start ot has it always done that?

Does it only do it when you're running at 95%if you lower it to 90 do you still get the pulsation?

Might be useful to share a pic of the still.

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Is the spirit outlet open to the air or submerged as in a parrot?

If open then it is possible for cold air to get sucked into the condenser if the still slows for a moment.

If the condenser is short the cold air gets into the still and cools the vapor in there causing a slight negative pressure which sucks more cold air in. Then as that air heats up it rushes out again, when the air has finished expanding the output stops for a moment and more cold air gets drawn in. Huffing.

If that is what is happening then a submerged outlet will stop it.

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Google "Parrot Surge Breaker".  Most of the vendors here offer them. It will reduce/eliminate the backpressure/surge cycle. 

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So I have a parrot but before the parrot it has holes on the side below the condenser, so it is essentially open to the air.  And @Silk City Distillers You may be spot on about the cold condenser water, I converted an old Air conditioner into our water chiller and the water will get down to almost 0 C, I'm going to install a temp probe and controller soon, but I'll be sure to watch the condenser water temperature.

Thanks for the replies guys

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So I’m not sure anyone is following this or cares. But if you are and you do I fixed the problem. I was reading a home distillers forum and saw someone talking about boiling chips. So I threw in some ceramic rings and problem solved. So I guess the gas had no nucleation point and the liquid was super heating and then flash boiling. 

 

So this worked but I never in a million years would have thought that a still with an agitator would have needed boiling chips. 

Anyone else need them in a commercial still?

  • Thanks 1

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I get this a little bit when I’m running to much heat to the kettle and also real cold water to the condenser.  

 

who made your still. Do they have any recommended fixes?

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Sorry i posted my last comment before i saw your response.   Boiling chips.. Hm i agree never would have thought about needing them.  Are you thinking that it was boiling then stoping then boiling then stoping?  Causing the pulsing? 

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