Still started huffing

[stillanoob]

HI All,

Equipment: 12 gallon pot still, all copper, propane fired, worm condenser of about 20 feet of 5/8" OD copper tubing in a 15.5 gallon keg as a flake stand. From the end of the Lyne arm there is about 7 feet of copper pipe in the air before it enters the flake stand and worm.

I have been experiencing huffing with my still. The funny thing is that it didn't used to. I built it at my shop and ran it there a number of times and had no huffing and a really nice even stream. I brought it over to where I ferment and on the very first run it started to huff. I figured that I must have bent the worm and introduced a low spot during transit as the coil had no support inside the keg so I took it back and made some supports and made sure it had a nice even incline. Next run, same thing. Thinking about it further I would imagine that a low spot in the worm would cause surging but not huffing. True?

I know the most common cause of huffing is vapor collapse. It does seem if I don't refresh the water in the flake stand and allow the temp to rise at the top of the flake stand it gets a little better but still huffs. The funny thing is that it ran at least 7 times at the shop with no huffing and now it does it every time. Are there other causes of huffing other than vapor collapse?

Thanks!

[still_stirrin]

Hmmmmmm....is it “breezy” where you distill now? Vapor collapsing in the Lyne arm to the worm perhaps (especially if it’s copper)? Insulate that line and see if that solves the problem.
ss

[stillanoob]

SS, no breeze where I am distilling. In fact less than there was where I used it with no problem.

Wouldn't insulating the lyne arm/copper pipe to the condenser tend to increase huffing? It seems like keeping the vapor warmer would lead to more drastic collapse when it hit the worm. I was actually thinking of ways to increase cooling on the way so the vapor is cooler when it hits the worm. Do I have this backwards?

It occurs to me, maybe the reason it is huffing in the new location is because it is LESS breezy and the vapor is hotter when it hits the worm?

[greggn]

It occurs to me, maybe the reason it is huffing in the new location is because it is LESS breezy and the vapor is hotter when it hits the worm?

By any chance, are you adding ice to the flake stand ?

[LWTCS]

By huffing do you mean vapor is visibly exiting your dick?
Or that you are getting some surging due to some measure of puddled condensate in the vapor path?

[stillanoob]

No vapor is making it past the condenser. I can run at 6 liters an hour with no problem so the condenser can knock down the slow rate I am actually running no problem. You can hear and feel it pulling air in. No ice in the flake stand. Water is about 53 degrees.

[43South]

I have a 50 litre copper alembic & have similar problem. My fix , I start with hot water 35c in condenser and only introduce cold from the bottom when the top is 65 to 70c .product is around 25c at spout.when it “huffs” it causes the bottom of the boiler to pulse up & down and it settles into a rhythm that takes a long time to settle out of.

[LWTCS]

If you can hear it sucking then that's indicative of a rapid vapor collapse.
Is there a gradient in your flake stand?

[Yummyrum]

Is there a gradient in your flake stand?

This would be the problem in my mind too .

A long liebig will huff if the coolant flow is too fast . The ideal operating point is where the flow is so low that the water is exiting almost boiling . When you run your hand up the liebig , there is a temperature gradient from cold through to untouchably hot .

Now consider a worm is like a coiled up liebig . ( the shell is removed and replaced by the water in the flake stand)

The operation is the same though . There must be a temperature gradient in the flake stand from cool at the bottom to hot at the top .
In the perfect setup , you would run water slowly into the bottom of the flake and have the hot exit from the top .

But thats not how most are used .They are juat a big barrel of water . The initial water temp will have a whole lot to do with it .The colder it is , the more likely for huffing before the run finishes .

[Saltbush Bill]

Is huffing really an issue .....besides the fact thay your still sounds like a dog panting?

[Yummyrum]

Is huffing really an issue .....besides the fact thay your still sounds like a dog panting?

Only when it spits out past the funnel . Nothing a bigger one won’t fix .

[Saltbush Bill]

pretty much how I see it Yummy.

[LWTCS]

A larger diameter coil should reduce aspiration.
But larger usually means more $.

Say, got any pics so we can see how well your flake stand will allow for gradient?
Diameter of pipe?
Diameter of coil?
Diameter of flake stand (bucket/reservoir)
Depth of bucket?

[still_stirrin]

“Huffing” is due to vapor collapse in the riser, or possibly the Lyne arm.

Since the piping is copper, it conducts heat (and cold) very easy, often faster and easier than the convection that transfers heat to the copper. As a result, the cold water in the flake stand is cooling your vapor pipe/Lyne arm inlet to the flake, causing the vapors to collapse in the path before they actually reach the worm.

The problem rectifies itself later in the run as the flake water warms up from the initial startup. And then, the huffing reduces.

My suggestion to insulate the riser and Lyne arm would help hold the heat in the piping until you are ready for it to condense in the worm. Also, it would warm the upper portion of the flake water sooner as the top of the worm would be warmer.

“Puffing” is a different condition when vapors are pushed out of the spout. This occurs when the vapors are not condensed fully within the product condenser. The primary cause is the boiler overpowering the product condenser, so you reduce heat input and subsequently, the vapor production rate. Another solution is a longer Liebig, or a shotgun condenser. Increase the conducting surface area for the vapors to transfer heat to as well as the “dwell time”, or time the vapors can contact the surface.

But increasing coolant water flow is often tried to solve the puffing problem. However, this can add to the huffing problem, thereby giving instability in operation with both “sucking & blowing” at the spout.

Heat transfer is an interesting study and highly appropriate for our hobby. Chemistry isn’t the only science we practice here.
ss

[stillanoob]

@LWTCS: The worm uses 1/2" ID copper tubing. The coil is about 10" in diameter. There are 7 turns plus the two sections of hard pipe at the top and bottom. The flake stand is a standard keg. Here are pics.

The coil has supports now and the pipe connecting the Lyne arm to the worm is a little shorter now as I built a proper stand for the flake stand.

@Still_Stirrin: Definitely huffing, not puffing. I have run the still as hard as 6 quarts an hour and it knocks it down no problem. Of course I am running waaaay slower than that. Ok, so you think the vapor collapse is happening before it hits the worm. I will try insulating the Lyne arm and connecting pipe next time I run.

There is a temperature gradient. I can and do refresh the water from the bottom and allow the hot water to run from the top. Last run allowing the temp to build up seemed to help a little. I guess what is bothering me is that it didn't used to huff and it was only after moving the still from where I built it to its new home that it started. I gather that operationally it doesn't affect the quality of the output so I guess I can live with it. I'll be interested to see if insulating helps.

Thanks for all the replies!

[Durhommer]

Nice machine there

[jonnys_spirit]

Hey Still, When I first built my liebig i had some huffing. I coiled up a piece of romex ground wire a little and stretched it out to maybe 12-14” or so and wove in a small piece of copper mesh on each end. Just enough to increase surface area and make a little turbulence. This stopped the huffing for some reason so i keep it in there. Towards the product end in mine. Maybe I keep a better gradient now with much slower water flow but the huffing went away and a little extra copper is welcome as far as I know. Might help might not. I didn’t recognize any significant slowing of takeoff either. It has caught a couple pukes but that cleans right up after running a bit on a strip.

Really nice still btw and love the flake stand and worm.

Cheers!
-jonny

[LWTCS]

Yeah farg.
I got nuthin.
That's a good looking outfit.

Maybe your lyne arm would be better off on a decidedly upward angel or a downward angle?

[stillanoob]

Thanks for the kind words about the rig. I had a lot of fun building it, it was the first time I had really worked copper, aside from soldering plumbing. It works well except for the huffing. Its greatest limitation is me learning to run it.

I will try insulating the Lyne arm next run and report back. Thanks for the help!