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Jun 08, 2022 View:

Running a vodka column with a Danfoss valve

Anyone running their column and modified pot still with a Danfoss valve?

We're having issues and want to make sure it's not us before I re-plumb everything.


We had our pot/column on one. Bulb read water temp inside the dephleg. We tried to hold 20C there. The inlet of the dephleg was on bottom with constant pressure. The outlet of the dephleg was on top and that is where the Danfoss was. Hope this helps!


Which Danfoss?  The integral unit (FJVA) or the remote bulb (AVTA)?  The integral unit has a small orifice bypass to keep water flowing to the internal temp sensor, the remote bulb has no bypass.  That remote bulb becomes problematic if you try to install it in the dephleg output plumbing (especially without a bypass).  The integral can be problematic when your dephleg is running cold water at high flow rates - the lag time will often cause cycling - wavering temps).

Both can work well, assuming you take into account some of these factors.  In both cases, tempering your input water through your PC to reduce the potential for cycling, can help smooth out temps - however this requires that your product condenser is not undersized, nor is your dephlegmator.


@Silk City Distillers @Stumpy's it's an integral.  

We run the cooling water into the condenser, out via the Danfoss sensor assembly, then into the second dephleg and finally into the first dephleg and out to the return.

We run a recirculated cooling water system using two 1800 gallon wine tanks cooled to 55F. We switch tanks once we hit 65F. The system operates at 75 psi.  

I can get both columns balanced (equally loaded plates) but no output.  I try to increase heat input or raise the dephleg temp the top plate floods and overflows. 

The water pressure maybe too high and needs to be throttled back. 

Another ideas?




You need a reverse acting Danfoss valve and here is how it should be set up.



Yours looks like one of our Danfoss set ups.  Try increasing the temp setting on the danfos and allow a little bypas at the danfoss valve.  If that doesn't work increase the temp setting more.  Also you should try bypassing the dephlegmator on column 1 completely.


Reply:58 minutes ago, Southernhighlander said:
Reply:56 minutes ago, Southernhighlander said:

I'm not sure why you are having trouble.  These usually work well.  Did you buy your danfos valve from us?




That's an interesting approach - you are basically controlling the input temperature to the dephlegmator, but not the flow rate.



Post a photo of the Danfoss valve label.


Reply:29 minutes ago, Silk City Distillers said:

Golden Beaver,  You should try bypassing the Danfoss valve to completely control the coolant flow manually to see if the still will function correctly manually.  If you cannot get correct functionality manually something is wrong other than the valve.  If you get correct functionality manually then there is something wrong with the valve.  

Also if you purchased the valve from us it will be a reverse acting valve.  If you purchased it yourself and did not purchase a reverse acting valve it will never work.  Did you just buy your column from us or your complete still including the still pot?



Reply:1 hour ago, Southernhighlander said:
Reply:1 hour ago, Silk City Distillers said:
Reply:4 hours ago, Golden Beaver Distillery said:

Yep that's the right valve.  We've been having our customers plumb them like this for some time with good results.   


I think you should run her manually.  Go ahead and bypass both plate columns with your vaper and also bypass both dephlegmators so that no coolant is going through them and see if you get any output and then we will move on from there to running one column.  It might be more expedient if we do this over the phone.  Call me when you set things to run  at 417-778-6908 and we'll get her lined out.


Reply:4 minutes ago, whiskeytango said:

I might have done something wrong, but I never liked the operation of the danfoss and when we ran one it always seemed to be open a little too much or too little too closed.

We switched back to metered needle valves and it works very well for us.  We have them on our single column still and two column vodka still.  For the most part we turn the still on, set each meter to whatever flow rate we know works best, and have to make very few adjustments between the beginning and end of the run.  Our cooling is a constant temperature, so our setup might not be ideal if you have coolant temperature creep.

Reply:19 hours ago, Golden Beaver Distillery said:

I'm not Paul (don't know his rigs), but I'd be glad to hop on a Facetime/Video call with you and walk through real time.

Based on what I'm seeing, you should be able to get this to work.

You should be starting with valves full open through Dephleg 1 and 2, and only enough flow through the PC Bypass to be able to just barely hit 100% reflux to load the plates, which will be a pretty small amount of overall flow.  It's a ball valve, so tiny adjustments will make huge differences in flow rate.  Input coolant at 55f is plenty cold enough to easily generate full reflux.

Too high of a flow rate through the Dephlegmators will over cool the reflux, and result in top plate flooding that will be challenging to settle down without turning off heat to the kettle and allowing the pressure to reduce so the plates can drain down.  Top plate flooding, or flooding on some seemingly random plate in the column, is almost **ALWAYS** due to subcooled reflux creating a kind of block in the column, as the liquid is cold enough to condense the vapor trying to pass through it.  Where the flooding will sit in the column will tend to be based on the backpressure generated by the kettle vapor generation.  Quickly turning off heat to the kettle will drop the vapor pressure and allow the reflux to drain down to subsequent plates.  Usually a quick on and off is all it takes to force the column to restack.

You said something about 75psi on the water feed, having the PC valve full open is going to be way too much flow.

Reply:48 minutes ago, Silk City Distillers said:

Golden Beaver,

I believe that Silk and Whiskey Tango's advice is spot on, especially Silks advice concerning your high pressure and backing off the coolant flow.  With that kind of pressure and the size of your lines you have far more flow than you need in this situation.   I rarely run stills anymore so the insight of people that run stills everyday can be really helpful in a situation like this.


Another thing to think about is the size of the wash and the size of the column.  If your wash volume is smaller and your low abv you might have a hard time just packing the column due to not enough alcohol in the wash to fill it causing a very slow / takeoff.  


Reply:2 hours ago, whiskeytango said: