Vapor Feed Size

googe

Hey all, my latest build has given.me the opportunity to run a plated column with a small vapor feed line. I've noticed some.positives to this but no answers. I've found the plates run more stable than running straight off the boiler, I used to get some surging every now and then when running the same column off the boiler. With the small feed a get a very steady plate. I used to run the same two.columns on top of each other directly off the boiler, ABV would be around 90~92%. With them separate and using the small feed I get a steady 94% bordering on 95%. Output is a touch faster too, power input is very very slight more. Ive discussed this on other forums and the view so far is, usong small feed line is introducing high speed vapor to a large area, causing some.benifit. Like holstein etc use large open areas in the boilers. Any one got some words of wisdom of why it's like this?.

Cheers

CothermanDistilling

I know some of the 16-18" columns just use a 2" pipe... interested to know details about the science also

Lloyd

It does seem logical that a restriction between the boiler and the column would increase And smooth out vapor speed, like blowing through a straw - the straw acts as a regulator of sorts.
How long does the straw (or 2" pipe) need to be? That's a tough question as 'some' may be good and 'more' may not be so good.

I've also marveled at the $100,000+ stills that feed the large offset column(s) with smallish looking 2" pipes.
A split column opens up a whole new set of ideas, challenges and variables.

brewsmith

@googe what size feed are you using for your 4"(?) column?

grim

With offset columns, I suspect it would be better to err on the side of smaller than larger, as you don't want vapor condensing on the interior pipe walls. Slower vapor speeds and more surface area increases the potential for condensation in the tubing, which is going to reduce efficiency since when the condensate finally makes it's way to the second column, it will simply drain out the bottom, wasted time and energy. In addition, vapor speed going into the column, or second column, will be significantly slower, since any condensation along the way is going to manifest itself as big drops in vapor volume.

It would probably make good sense to insulate any vapor lines between the boiler and column, as well as between columns.

Pre-condensor plumbing I think would act in an opposite way, and is likely going to see a benefit from the additional surface area acting as a passive heat exchanger, especially with corresponding slower vapor speeds.

I've always thought high vapor speeds going into a shotgun condenser have the possibility of pushing faster vapor speeds through the center tubes directly in front of the feed tube, especially if there isn't a larger expansion area prior to the condenser tubes. Always wanted to try adding additional large diameter pipe sections in front of the condenser to create a slower, more laminar vapor path that would feed all condenser tubes equally.

Lloyd

A ball on top of the product condenser @grim?

googe

3/4" brewsmith. Good points grim about the vapor feed size and condensation. And the small line going to the pc. I havnt had any probs with vapor by passing the PC, I have 4 inner tubes, so maybe it's dispersing the fast vapor ok, no centre tube. That's something I might look into though, need it working to the best ability, when I'm trying to make.the rest of the still.operate at optimum level. Any more thoughts?.

DocPorter

My opinion is that the increased vapor speed in the small vapor feed line puts much more back-pressure on a boiler which gives a more consistent flowrate to the column.

I disagree with insulating the vapor line. I think it's unnecessary. Let it act like a plate.

googe

That's something that came up on another forum docporter, the back pressure. Seems many factors are the reason.

Myles

A few years back I had a discussion with Harry about reflux condensers. It was about side entry into the reflux coil chamber at the top of the coil. I had my doubts but was wrong. It worked.

With smaller vapour tubes and side entry there is loads of turbulence which should sort out the vapour split into the tubes in a shotgun.

Now if you need an axial vapour entry, how about adding a fixed blade turbulator above the condenser tubes to increase the vapour split so it was even between all the tubes?

FullySilenced

@Myles something like a stationary fan blade?

CothermanDistilling

twin, counter-rotating, free-floating turbine blades... bling-bling!

FullySilenced

Knowing Harry could have been the suggestion... I miss him... being around the forums much

grim

I don't think it even needs to be that fancy, Lloyd's suggestion of a "ball" would probably do it. If you had a ball with 4" TC fittings, and put it at the top of the product condenser, I suspect it would create enough turbulence, and disrupt any laminar flow.

Lloyd

We seem to be getting a lot more requests for balls lately.
I may need to explore that after the holidays. A pair of reducers would do the job but not as elegant.

dad

My wife says that all the time...

TheMechWarrior

:D

Myles

I fitted a stationary fan blade turbulator inside the ball on my own pot still. Designed to 'swirl' the vapour into contact with the ball surface to encourage passive reflux. Just wish I had included a sight glass.
Possibly the next evolution when I modify it again!

grim

Ah very neat. How large is the fan? Same diameter as the ball?

Myles

No I went for 1/2 diameter so it sits in the lower part of the ball. It is only tacked in place at three points so as to allow condensate easy access back to the boiler. It will be modified to take a larger diameter vapour inlet when I mount it on a new copper boiler as a striping still.

captainshooch

@Myles Oh man that is some awesome copper work. =D>

Smaug

Thats one of Myles older gadgets Captain. He fab'd that one up a few years ago.

Ya otta see how many things Myles has built and how many times he has re configured his work space!

googe

I havnt had any trouble with vapor by passing the PC.

captainshooch

I'll jump at any chance to see other set ups. Just so unfortunate we are all so far apart.

brewsmith

Has anyone done any comparison between running a 4" column with a 4" feed from the boiler vs a 2" feed (such as that coming off a standard keg) and noticed any difference in plate stability? Just wondering if that diameter difference is great enough to effect performance, or if you really need something as narrow as 3/4"

dad

I have run my 4" on a 4" modified keg and had problems...it seemed to fill with vapor, equalize and dump to the boiler as soon as I start takeoff. I thought I didn't have enough power to run it.

As a lark I tried it on an unmodified keg, 2", with a 2" to 4" endcap. I may still be underpowered to maximize takeoff, but it was stable.

shindig

I was wondering about the 8" procap column to a 4" Lynn arm feeding a 4" condensor . Thoughts? No one seems to be running anything sized that way.

Smaug

We are waiting for Grim to fire up.

FullySilenced

The Vapor just speeds up through the 2" opening then, there is a slight drop in pressure which would be like a very small refrigeration process... high to low pressure... and then it would operate exactly as a 4" opening would... or that's how i see it

FS

dad

Could the vapor speeding through the 2" restriction keep reflux or liquid from dropping back to boiler. Almost like a plate.

FullySilenced

Dad I don't think it would be like a vacuum clean by any means... liquid would run back to the boiler as it see it ... but if you got a theory other than mine i am all ears... :D and from that smiley, teeth too i guess :))