Having trouble running my VM on a Neutral spirit run

[Big L]

Its mainly going fine and was getting a fairly consistent 94% - a few times it would drop off and then all I would do is shut off the valve and let it re-equilibrate. I am making small adjustments to the cooling water to keep the coil condenser outlet at between 40-50 DegC

I have also been gradually upping the power from initially about 900W to now at about 2000W

I started with 23 Litres of 40%

Its now stuck around 88% and I cant seem to get it back up through shutting the valve off and letting it settle. I am wondering what I am doing wrong. Why does it occasionally drop off and then return to normal when I shut the valve.

About to shut it off for the day - started pretty late and will resume in the morning first re-equilibraiting

All the best

[Tummydoc]

How much have you drawn off? As the alcohol is depleted the ABV will drop late in the run even with reflux. In fact you'll see it drop fairly quickly as you approach tails.

[Expat]

Sounds like your packing isn't dense enough. If you're able to apply so much power without a change, then most of the distillate is probably just dropping back into the boiler.

[kimbodious]

Are you using a PID? Is your column insulated? Are you flooding and getting condensate coming out the offtake?

[StillerBoy]

Not knowing what type of packing being used nor what size and height the column is, nor the style of VM it is, it's difficult to advise on how or where you issue it.. but a VM pretty is run similar to an LM

First the water outlet temp is to warm to properly operate an LM column.. the temp of the outlet water should be maintain at a stable temp in the range of 30c/ 85*F for best refluxing ability..

Your power range should be maintain at the 1800 - 2100w.. start with about 1800w, stabilize for 30 min, extract fores at about 100ml over 15 min, then heads at 100ml over 10 - 12 min, then into the body, crack the take off value just little more maintain the top of column temp stable at whatever the temp was once the heads were removed..

If the top the column temp moves up even a tenth of a degree, cut back on the take off rate..

Also, once out the heads section you want to increase on power, say 1000w more, that will help increase the speed of the take off rate a little.. be mindful of the take off rate (time wise) as the body section end and the tails start, the flow rate will drop off some.. in the early tails, I usually cut back on the take off rate for the next 100 -200ml, then move on to extracting the tails at a fast rate for feint..

Mars

[Yummyrum]

Why does it occasionally drop off and then return to normal when I shut the valve.

Because when you shut the valve , you are putting the still in full reflux and this will allow the remaining alcohol ( not e I didn’t say Ethanol) to work its way to the top if the still .So when you open the valve , you are collecting the last of the available Alcohol in the still ,it’s not being returned to the packing so then the ABV will quickly drop again .

[Big L]

Hi All,

Its a standard VM - 2" copper with 1m of 6mm raschig rings, then a coil reflux condenser on top of that after a T with a product valve coming off that. Unfortunately i don't have an electronic temp sensor - have a big dial one so find it difficult to guage exact temperature - i will get an electronic one for my next run.

So i've drawn off 7 750ml bottles of about 92%: 7*0.75*0.92 = ~ 4.9L of ethanol

I charged it with 23L of 40% : 23*0.4 = ~9.2

I also just drew a bit off what was in the boiler out of the tap at the bottom and its reading below 0%....

Apologies for the likely foolish questions

[MartinCash]

I have a VM column not unlike yours, but mine is packed with 1.2 m structured copper rather than raschig.
I don't work in watts because I use gas.

Some thoughts:

• Has the temperature of your condensate changed as the run progressed? This can throw off the reading;
• I rarely worry about regulating PC and RC water temperatures. I run cold water (in winter it would be ~8 C) and I still get good 95% neutral. YMMV, but my advice would be to pay attention to other factors first.
• Off a 40% charge like yours I would have expected quite a bit more. In my VM the tails can come suddenly, but always preceeded by a rise of ~0.2 deg. C. I can hit tails while still above 91-92%.
• If I take too much product too quickly, I'll smear tails. I can take 2.5L / hr wide open, but more than ~ 1 L / hr and I will smear tails. Was your take-off rate too high perhaps?
• A reading below 0% can only happen without temperature compensation. Are you using the right kind of hydrometer (proof / traille) and compensating for temperature as I mentioned in my first point above?

[OtisT]

Hi BigL. Just my opinion, but one general issue with your spirit run process is that you are applying too much power to get good separation on a 2” packed column. Once vapor speed becomes too fast your packed column stops separating properly and you will experience more smearing.

The guidance I have seen on vapor speed in a packed column is that 20’/second is about the fastest you can run and still get good separation. I do find this guidance to be accurate with my 2” and 3” columns. So on a 2” column you should find a max effective power near 1500W, 3000W max for a 3” column, and 6000W max for a 4” column. There is a vapor speed calculator on RADs calc page, located on HD in the CALCS section.

Otis

[bluefish_dist]

Hi BigL. Just my opinion, but one general issue with your spirit run process is that you are applying too much power to get good separation on a 2” packed column. Once vapor speed becomes too fast your packed column stops separating properly and you will experience more smearing.

The guidance I have seen on vapor speed in a packed column is that 20’/second is about the fastest you can run and still get good separation. I do find this guidance to be accurate with my 2” and 3” columns. So on a 2” column you should find a max effective power near 1500W, 3000W max for a 3” column, and 6000W max for a 4” column. There is a vapor speed calculator on RADs calc page, located on HD in the CALCS section.

Otis

Agree 100%. I too have found the 20ft/sec to be a good limit for production. That gives a takeoff of about 1 qt/hr for 2”, 2qt/hr 3” and 1 gal/hr 4”. I also ran a 6” at 8000 as that’s all the power I had. At 12,000 w it could do 2 gal/hr.

Height is key to purity. Imho 15 plates is a minimum for azeo and 20+ is better. For scrubbies that means 60” minimum. I ran a full 8 ft on the 4” and 6”.

[Big L]

[*] Off a 40% charge like yours I would have expected quite a bit more. In my VM the tails can come suddenly, but always preceeded by a rise of ~0.2 deg. C. I can hit tails while still above 91-92%.
[*] If I take too much product too quickly, I'll smear tails. I can take 2.5L / hr wide open, but more than ~ 1 L / hr and I will smear tails. Was your take-off rate too high perhaps?
[/list]

I tried running again today - following above advise but i cant seem to get the column back to the right conditions and the alc % of the product is continuously dropping with the temperature increasing all the while. Also it tastes and smells horrible like at the end of a run.

I tried running at a lower temperature, changing the cooling water temperature etc

I still cant work out where all that missing booze is?

All the best

[StillerBoy]

I still cant work out where all that missing booze is?

Posting a picture of the unit would help.. Plus I believe you are lacking understand of the sections.. if the temp is changing as you say it is, that tails, and tails are hard to compress if you lack the understand of what is happening during a run..

Mars

[bluefish_dist]

For a neutral, temperature should not rapidly change until tails. Reflux should be increased slowly during the run to keep the abv/ temperature stable. Ie reduce takeoff rate slowly to up reflux. On my still that means I start at about 4-5 turns open and slowly close it by 1/2 turn at a time until I get to 2.5 turns. At that point output is much slower. Then if I am still not into the tails, I can reduce power until output is super slow or I can no longer hold temp/abv.

[Tummydoc]

]

I tried running again today - following above advise but i cant seem to get the column back to the right conditions and the alc % of the product is continuously dropping with the temperature increasing all the while. Also it tastes and smells horrible like at the end of a run.

I tried running at a lower temperature, changing the cooling water temperature etc

I still cant work out where all that missing booze is?

All the best

Sounds like your well into the tails. ABV will rapidly drop, temp rise, and product not drinkable. Your run is done. You harvested most of the alcohol on day one. But your yield calculations are off. Either a specific gravity reading was wrong, or you lost alcohol vapor through the top of the still (less likely)

[Big L]

Thanks for the wise words everyone - I think i need to sort out a electronic temperature sensor and a valve i have more controll over - its 42mm ball valve at the moment.

All the best

L

[OtisT]

Oh ya! Fine tuning a 2” VM column with a ball valve would be a trick. Much of the time my gate is open less than 2 turns out of 8 and I do fine tuning in 1/4 turn increments. It’s hard to get that level of resolution with a ball valve. With a ball valve VM you will spend a lot of time over and under correcting to find the sweet spot of good separation.

Otis

[NineInchNails]

Big L, have you confirmed whether or not you are losing vapor out the top of your still? If your running your reflux coil too hot then vapor will pass right past the coil. Also I'd stuff copper mesh in and around the coil and that will help.

On this page there is a good guide to running a VM still. I followed that for my very first run and it worked out great.

My column is relatively tightly wound copper mesh and it works great. You really should put a thermowell in the take-off portion of the tee to monitor your vapor temp. I have a thermowell in the boiler to monitor boiler temp. When the boiler get to around 170F I remove the sensor and put it in the take-off to monitor vapor temp. Once the vapor gets into the 170s F you will start fully refluxing for at least 30 min (some go longer). Notice your vapor temp is stable in the 170s. Start taking off the four shots and the vapor temp stays stable. Start taking off the heads and the temp should be stable. Same with hearts. Once the output starts to reduce a little I full reflux to stabilize for a while. I crack the valve, take off product and vapor temp is still stable. All of a sudden the output dwindles, temp rises fast, product turns foggy and once my vapor temp becomes 205F I just shut down.

Best if you use a gate valve. Perhaps 1". That's what I use, but mine is a 3" column. Shop around and you will find one at a decent price, just keep searching.

[MartinCash]

Thanks for the wise words everyone - I think i need to sort out a electronic temperature sensor and a valve i have more controll over - its 42mm ball valve at the moment.

All the best

L

I think most people here have found gate valves much easier for the fine control that they offer. Mine is like OtisT says, I find myself sometimes adjusting 1/4 turn or less, which is probably a fraction of a millimeter opening.

[NZChris]

My gate valve control wasn't fine enough, so I ground a V into the gate. I'd prefer a finer adjustment, but it's what I've got and I can live with it until I find a suitable needle valve.

[Big L]

Big L, have you confirmed whether or not you are losing vapor out the top of your still? If your running your reflux coil too hot then vapor will pass right past the coil. Also I'd stuff copper mesh in and around the coil and that will help.

On this page there is a good guide to running a VM still. I followed that for my very first run and it worked out great.

My column is relatively tightly wound copper mesh and it works great. You really should put a thermowell in the take-off portion of the tee to monitor your vapor temp. I have a thermowell in the boiler to monitor boiler temp. When the boiler get to around 170F I remove the sensor and put it in the take-off to monitor vapor temp. Once the vapor gets into the 170s F you will start fully refluxing for at least 30 min (some go longer). Notice your vapor temp is stable in the 170s. Start taking off the four shots and the vapor temp stays stable. Start taking off the heads and the temp should be stable. Same with hearts. Once the output starts to reduce a little I full reflux to stabilize for a while. I crack the valve, take off product and vapor temp is still stable. All of a sudden the output dwindles, temp rises fast, product turns foggy and once my vapor temp becomes 205F I just shut down.

Best if you use a gate valve. Perhaps 1". That's what I use, but mine is a 3" column. Shop around and you will find one at a decent price, just keep searching.

Yeah not losing anything out the top - its about 2cm from the ceiling of the room its in and so i'd definitely know haha - once or twice i lost a little but re-adjusted the cooling water.

I was using those and some others on the site - I think the main problem was no gate valve - i did indeed find it really difficult to get right.

The issue is finding a valve that fits in with the fittings I have - really don't want to have to re-solder anything - once i've got this one sorted / understand more about it i wanna make a 4" one with a buddy of mine who as an industrial plumber has access to lots of copper pipe and will definitely change a few things.

I do have a thermowell in the takeoff position but have a dial temperature meter - i need something digital i will sort out before running again.

[Big L]

Sounds like your well into the tails. ABV will rapidly drop, temp rise, and product not drinkable. Your run is done. You harvested most of the alcohol on day one. But your yield calculations are off. Either a specific gravity reading was wrong, or you lost alcohol vapor through the top of the still (less likely)

Yeah on my 8th bottle it rapidly dropped and tasted nasty - good i was separating the bottles as advised by someone on another post.

I cant really see where my yield calculations might have gone wrong - It was definitely 23L and i had already run it through the pot still once - so using a spirit hydrometer it read 40%. This was all at room temperature when i was measuring.

My specific gravity readings from the mash fermenting agree with that 40% of 23L too. Very strange!

[Yummyrum]

I use a Ball valve with no issues . I originally used it on my 2” LM/VM combo ( reduced to 1.25” at the takeoff ) .Then on my Flute and 4” VM .
It’s an 1.25”
Before I installed it , I marked the handle to show when it was just closed . This makes adjustments dead easy as I can just crack it open a bit more for fores removal ( the second mark ) .The third mark is where I normally use it on the flute and about midway between 2nd and 3rd marks are on the 4” VM . Not saying these are where you should set yours , just rather showing that it can be easy to use if you have marks

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[The Baker]

That looks like a reduced flow valve, not 'full flow'.
What is the diameter of the actual hole the liquid flows through?
I am interested, looking at drain valves etc. for myself.

Thanks.

Geoff