Managing a CCVM Still

[Biff Henderson]

I've recently converted my 2" Boka to a traditional 2" CCVM -- modified keg (+5500W heating element, PID controller), 48" SS column to a 2" tee/90 degree elbow on top of a shotgun condenser. I've completed my vinegar run, am preparing for the sacrificial run. I have a few questions - I understand I can operate the still in Pot Still mode or CCVM mode. I am interested in doing both and am going to be experimenting with both over the next few years.

If I am running in pot still mode, I will use a stripping run followed by a spirit run. For my stripping run, I will not have any copper scrubbies, I will just blow through it as quickly as can. I'll take my time with my spirit run. There is ample material on this site for review regarding pot stills.

But when I am using the still in CCVM mode - I have a few other questions (apologies if these have been answered previously). Is there general guidance around how long to allow reflux to occur, or when to raise the condenser coil allowing the vapor to make its way to the shotgun condenser? Would I let the column reach equilibrium and then pull some off, restore equilibrium and pull some off (wash, rise, repeat)? Is it a timing mechanism (20 minutes on reflux, 10 minutes off reflux)? Is it a one time process (to raise the condenser coil) or will it require frequent management? What is the general guidance here? Thanks in advance.

Biff

[kimbodious]

gday Biff
I have 2” CCVM using a 2200W keg boiler and a power controller.

I put the RC in the lowest position (total reflux position) and set the recirculating cooling water running at the same time I turn the power on to the boiler.

As soon as the heating up noises start to decrease (reaching boiling point) I back off the power controller to ~ 1200W. Once I start to see condensate through the sightglass I back off the power controller to around 400W. I leave my still in total reflux for around 45 minutes or until I notice a change in the boiling sounds or flow of condensate.

I raise the RC about an inch and increase the power to around 1200W. I draw off 150 mls foreshots very slowly at about 1 drip per second. I raise the RC another inch or so to draw off heads at 2 drips per second.I gradually raise the RC and increase power during the heads extraction so that by the time I have collected around one litre the RC is in the highest position and the power is around 1450W. I leave it at those settings for the rest of the run.

With those settings I am achieving a steady thin stream at around 1.25 litres per hour of product.

TIp #1 Don’t attempt to run a CCVM without a power controller.
Tip #2 Don’t pack your column too tightly
Tip #3 Don’t rush the run or your product will suffer

[still_stirrin]

Biff,

Kimbodious has pointed out an obvious fact...You don’t run a VM like you would run a LM. Your questions seemed to reflect your experience with the Boka, a LM reflux head. The Boka manages the reflux ratio by the liquid takeoff rate and timing. As you’ve asked, you keep the purity high by keeping the takeoff slow relative to the vapor production in the boiler. That’s the LM operation.

The CCVM will function differently. It manages reflux ratio by the ratio of vapor that advances to the product condenser versus the vapor that proceeds to the reflux condenser. The “position” of the valve is what creates this ratio. The advantage of the VM reflux head is that the ratio is constant for a single “valve” position independent of the vapor production in the boiler. However, the CCVM is influenced by reflux condenser cooling power (water flow rate and condenser coil position) in it’s function as a “valve”. Conventional valves are not likewise affected by the water dynamics, just the position of the valve.

So, don’t expect to run the CCVM like you would run your Boka, although it certainly will operate much faster. And, it is easier to just “set and forget” as you progress through the run. It is the easiest of all designs to operate although each method of reflux management has its advantages and disadvantages.

Of note, I like the LM design for compressing heads at the start of the run. But my conventional valve controlled VM is very good at managing the reflux ratio throughout the balance of the run, pushing the tails to the very end. Yes, my reflux head is a combination LM/VM head...I like it a lot!
ss

[kimbodious]

Dunno about adjusting water flow rate SS, I just set and forget the water flow. You are certainly right about the CCVM being the easiest (and most boring) reflux still to operate compared with a CM and a VM! Mind you they also might have been easier if I had the sightglass back then

[still_stirrin]

... compared with a CM and a VM!

You MUST mean to say LM here.

A CCVM is a VM, just that it uses the reflux condenser as the “valve”. If water flow varies, the cooling power changes and the effectiveness as a “valve” can vary too. Perhaps the sensitivity of yours is below the threshold of measurement, so you don’t notice the effects. A mechanical valve does not have this interaction and as a result, it is more stable without sensitivity to reflux coolant flow or vapor production rate.
ss

[Biff Henderson]

You're right SS - I do have some experience (~20 runs) with my Boka - still a rube I know - have gotten used to managing it fairly rigorously as I sought the optimal ratio of takeoff/purity -- while keeping equilibrium in the column. A desire to use different ingredients led me to the CCVM/Pot Still combi.

Based on prior readings, my understanding is that a CCVM/Pot Still will be easier to manage - although I expect "boring" is not a term I'll use. The test I have run thus far indicates water thru the RC will not be a variable, as I have plenty of pressure from a March pump. I'm using an inline thrumometer on my water return so I can monitor the effectiveness of the RC as a "valve" -- although I've not had a true test using real ingredients over multiple hours. Ice is always an option if temperature begins to become a variable requiring management.

Really looking forward to my Sacrificial Run.

Thanks for your feedback Kimbodious and still_stirrin - very clear explanations of the mechanics and the process.

[kimbodious]

... compared with a CM and a VM!

You MUST mean to say LM here.

A CCVM is a VM, just that it uses the reflux condenser as the “valve”. If water flow varies, the cooling power changes and the effectiveness as a “valve” can vary too. Perhaps the sensitivity of yours is below the threshold of measurement, so you don’t notice the effects. A mechanical valve does not have this interaction and as a result, it is more stable without sensitivity to reflux coolant flow or vapor production rate.
ss

Nope, a VM has the valve after the offtake and a RC, the CCVM has the RC acting as a cold zone valve before the offtake, different enough to draw the distinction and by how they are operated. I set the coolant flow such that I can achieve total reflux in the lowest position and leave it at that luxuriant flow rate. I think of the RC as a zone of coldness instead of an actual physical valve obstruction.

F5B56BB5-F917-422B-B990-1FC8AC6927AF.jpeg

[kimbodious]

Based on prior readings, my understanding is that a CCVM/Pot Still will be easier to manage - although I expect "boring" is not a term I'll use. The test I have run thus far indicates water thru the RC will not be a variable, as I have plenty of pressure from a March pump. I'm using an inline thrumometer on my water return so I can monitor the effectiveness of the RC as a "valve" -- although I've not had a true test using real ingredients over multiple hours. Ice is always an option if temperature begins to become a variable requiring management.

“Boring” in that once you are in hearts all there is for you to do is to swap jars, there is nothing required for monitoring and changing settings.

When I was using a recirculating water chiller I was puzzling over how the vapour interacted with the slightly tepid RC. You can feel from the outside of the column the cooler area where the main of the condensation has occurred. Compare this diagram with the previous oversimplified one.

EF600F99-DC12-4A25-BA2F-C2155DFDD939.jpeg

[Biff Henderson]

Having a tepid zone compared to a cold zone seems more desirable as I'll have more reflux occurring - is that correct? And I think I understand the distinction Kimbodious is trying to lead me to -- the cold zone encourages reflux while also acting as a valve. The valve acts as a ceiling and does not nothing to encourage reflux, thereby creating the distinction between the two. I have enough water pressure and temperature management to be able to allow the RC to act as a valve. I think (emphasis on think) I prefer a tepid zone so more of the RC is utilized while still blocking any vapors escaping the top. I'm splitting hairs possibly...

[Twisted Brick]

Having a tepid zone compared to a cold zone seems more desirable as I'll have more reflux occurring - is that correct?

I'm still working on the nuances of my 3" CCVM, but to me, a cold zone is preferable to a tepid zone. I believe a consistent (cold) temp zone that allows no (or little) vapor to enter performs more effectively, eliminating a second variable. It also isolates the function of the movable 'valve' in the manner Kimbodious runs his with constant water flow.

[kimbodious]

There is a happy medium. Too much and too cold water may extend the cold zone further down than you’d want. I was only interested in the tepid zone when my recirculating cooling water was around 40C. So with a tepid zone you get the same amount of reflux but occurring across a longer section - when you feel the column from the outside you can feel where that is by the abrupt change in temperature.

I am now recirculating cooling water from an inground pool where the temperature only gets up to 32C so I am back to having a luxuriant level of cooling water flow. Well a little too much towards the end of pot still runs where I get mild huffing at the product condenser when the vapour temperature is really high. The vapour temperature is really high when there is very little ethanol in the product (~12%) so I use the onset of huffing as a signal to shut the run down.

[kimbodious]

Biff, my RC is more like a twist than a coil. The OD of the CSST was 1/2” and I just could not wind a coil tight enough for it to fit inside the column and be able to slide it up and down. I wove SS scrubbers in the twist to ensure good contact with the walls of the column. Even with my dodgy twisted hairy RC there’s only about 4” difference in height between total reflux and the 50:50 split as indicated by the yellow zip ties

BA71BA24-0B07-4E50-9DD7-990E268003F2.jpeg

[RC Al]

Having a tepid zone compared to a cold zone seems more desirable as I'll have more reflux occurring - is that correct?

I'm still working on the nuances of my 3" CCVM, but to me, a cold zone is preferable to a tepid zone. I believe a consistent (cold) temp zone that allows no (or little) vapor to enter performs more effectively, eliminating a second variable. It also isolates the function of the movable 'valve' in the manner Kimbodious runs his with constant water flow.

The cooler the returning reflux, the more energy/power needed to revaporise it - tepid is good if managed properly