VM operation question

by **technofaux** » Thu Mar 28, 2013 12:09 pm

Hello all,

I have been spending the past week or so converting my old nixon-stone into a VM still and finally ran it a couple times this week. I don't seem to be getting the output %ABV that many see from their VM still, and also had a terrible time today getting a decent flow rate on the takeoff. I would appreciate some thoughts on what I may be doing wrong. Here are some specifics on my setup and an overview of my run for background.

Still configuration:

2" column, approximately 5' tall (column is insulated up to reflux input line and packed with about 4' of copper scubbers.) I have a 10" double helix coil condenser at an angle coming off the column from a 2" Tee. The product takeoff comes off the Tee and a 2" 90 degree elbow, then goes into a reducer to a 1" ball valve, then on to another 90 degree and into a liebig product condenser (about 3' long 1/2" pipe inside 1" pipe.) then into my parrot.

I start off getting to equilibrium and letting is stabilize for an hour or so, then I draw off the foreshots. I close the valve and let it equalize again and then pull off the heads. It is here when it really seems to slow down. I have increased the gas heat quite a bit and am not loosing vapor from the top condenser, but my flow is terrible, probably around 500 ml every two hours. I tried opening the valve all the way, halfway, etc, but I am just not getting a good flow. The abv is coming out at 90% also during heads and through much of hearts.

Any ideas on what may be wrong with the flow and low abv%?

Thanks,
Technofaux

by **MacStill** » Thu Mar 28, 2013 1:12 pm

G'day TF,

are you doing stripping runs and running low wines, or trying to run straight wash ??

A VM is a excellent unit for neutral production, however they dont run too well on low ABV boiler charges.

Have you read Kiwi's VM operation tutorial ? I'd say once you've read it over once or twice you'll probably have the answers you seek.

Cheers.

by **technofaux** » Thu Mar 28, 2013 9:52 pm

MacStill wrote:G'day TF,

are you doing stripping runs and running low wines, or trying to run straight wash ??

A VM is a excellent unit for neutral production, however they dont run too well on low ABV boiler charges.

Have you read Kiwi's VM operation tutorial ? I'd say once you've read it over once or twice you'll probably have the answers you seek.

Cheers.

Many thanks for the quick reply Mac.

I was running a straight wash, so that is likely the problem. I will take a look at Kiwi's tutorial you referenced and start over. Thanks again for the assistance, it was driving me crazy!

TF

by **MacStill** » Thu Mar 28, 2013 9:55 pm

Straight wash is your problem, you need to run low wines in you VM :handgestures-thumbupleft:

by **JagCrusher** » Fri Mar 29, 2013 2:33 pm

...I have a 10" double helix coil condenser at an angle coming off the column from a 2" Tee. The product takeoff comes off the Tee and a 2" 90 degree elbow, then goes into a reducer to a 1" ball valve...

You could also try stuffing a scrubber just above the take-off point/under the reflux condenser coil. It can help to slow the vapour down a little and redirect it into the take-off arm.

by **technofaux** » Sun Mar 31, 2013 8:54 pm

Thanks again for the pointers. Takeoff was much better with the low wines. Still only outputting around 90% abv. Do I need to increase reflux to drive up abv? Is the best way to do that with a VM by slowing down takeoff, or increasing packing? :think:

by **MacStill** » Sun Mar 31, 2013 9:07 pm

We're gonna need a heap more info mate, to guide you to perfection ;-)

Your take off rate on a still that size should be around the 1 litre per hour mark, the slower the better and even 800ml per hour is good.

People need to remember there are no short cuts here with neutral production, slow n steady is the "only" way :handgestures-thumbupleft:

by **BackyardBrewer** » Sun Mar 31, 2013 9:45 pm

MacStill wrote:the slower the better and even 800ml per hour is good.

People need to remember there are no short cuts here with neutral production

Yeah my timing on reflux is about 200ml every 15mins. I wish it had more control at the end of the run so I could ramp it up during the tails but it does deliver a very very polished neutral at that take off rate.

by **technofaux** » Mon Apr 01, 2013 1:00 am

Thanks, I will have to monitor my collection rate a little more closely. I only had about three gallons of low wines most recently (at 45% abv) when I re-ran through my VM. From start-up to shut-down it was about 4.5 hours. I collected a little less than a gallon in total. I would guess it was running close to 1000ml and hour. Any pointers on how to improve on the neutrals would be greatly appreciated. I am trying not to rush it too much. I think I need to get my hands on some platinum cured silicon tube so I can watch the reflux more closely. All I do now, is look down the end of the reflux condenser to see how much is collecting go gauge the reflux ratio, but it is a little hard to see past the vapor to really tell. I am including a picture of my VM also for reference. I is a little non-traditional on the design because I kept the pieces from my old nixon-stone in more or less the same configuration, around the reflux condenser, but I don't think that should matter too much (let me know if you disagree with the configuration?) I am also curious if I should have the end of my reflux condenser completely open as it is, or should I have the end closed off more? Disregard the ugly supply pipe, not quite an entry to still porn yet. :oops:

photo (2).JPG

Thanks again!

by **MacStill** » Wed Apr 03, 2013 10:00 pm

"I think" 1/2 your problem might be that your take off is higher than your condenser, it's a bit hard to say for sure as I've never ran a still configured that way.

Also you might find it's just in the valve adjustment & possibly a gate valve we be a better option allowing finer tuning.

How fast are you trying to collect product ? it sounds as if it's acting more like a pot still than a refluxer :think: