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product condensor on VM

These are various style condensers for many different applications.

Re: product condensor on VM

Postby Wai`ona » Sun Sep 13, 2009 3:45 am

punkin wrote:It's epic. let it ride.

Destructomutt's legacy? :shock:
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Re: product condensor on VM

Postby punkin » Sun Sep 13, 2009 4:23 am

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Re: product condensor on VM

Postby Harry » Sun Sep 13, 2009 5:42 am

And just when everyone is getting comfortable with how & why VM works (all good stuff)...I'm currently bench testing a VM design innovation that will virtually eliminate all the tricky variables like Reynolds calcs., gate valves & such.

But I'm gonna make some money outta this one before I release any more info (& no, I'm not trolling for backers). Suffice to say it is Vapor Management in the TRUE sense of the phrase.
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Re: product condensor on VM

Postby minime » Sun Sep 13, 2009 6:27 am

Harry wrote:I'm currently bench testing a VM design innovation that will virtually eliminate all the tricky variables like Reynolds calcs., gate valves & such.


You've got me sitting on the edge of my seat Harry! :8)
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Re: product condensor on VM

Postby airhill » Sun Sep 13, 2009 8:33 pm

"Airhill,

Sorry, this is new territory for me!"

No worries mate, new territory for me too, you should have just said I don't get offended :)

And now is everyone going to theorise on what Harry has up his sleeve? :roflmao:
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Re: product condensor on VM

Postby Moon Masterson » Sun Sep 13, 2009 10:22 pm

airhill wrote:And now is everyone going to theorise on what Harry has up his sleeve? :roflmao:


I'm glad mine is still in the R&D phase, but I'm wondering what's up too! I'm having enough trouble just trying to figure out how the established principles work! I wonder how long Harry is going to keep us on the edge of our seats? :)
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Re: product condensor on VM

Postby airhill » Sun Sep 13, 2009 10:36 pm

Moon Masterson wrote:
airhill wrote:And now is everyone going to theorise on what Harry has up his sleeve? :roflmao:


I'm glad mine is still in the R&D phase, but I'm wondering what's up too! I'm having enough trouble just trying to figure out how the established principles work! I wonder how long Harry is going to keep us on the edge of our seats? :)


Too late for me :roll:

If there is no gate and no worrying about Re etc I suspect Harry might be not be worrying about reflux and trying to split the vapour on density. Hmm slow spin like in a vortex filter or extra long way to the top condenser with a clever take off?
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Re: product condensor on VM

Postby Harry » Wed Sep 16, 2009 9:39 am

:roflmao: No mate, no 'vortices' in this baby. :roflmao:

But to be fair to my own forums members, I have announced it on Yahoo Distillers...


http://groups.yahoo.com/group/Distillers/message/45754

Of course discussion is welcome on any forum.
.


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Re: product condensor on VM

Postby minime » Wed Sep 16, 2009 10:53 am

Harry wrote::roflmao: No mate, no 'vortices' in this baby. :roflmao:
http://groups.yahoo.com/group/Distillers/message/45754



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Re: product condensor on VM

Postby airhill » Wed Sep 16, 2009 6:29 pm

Sounds like Harry's designed the 'perfect' CM head :roflmao: :roflmao:
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Re: product condensor on VM

Postby Moon Masterson » Fri Sep 25, 2009 1:54 pm

I have been doing a LOT of thinking, as a result of the information that has been shared on this topic. A part of my initial interest was trying to gain a better understanding of vapor flow, and being able to "see" what happens in the reductions and at the takeoff port. Since I am still in the R&D phase, this topic has been very helpful to me, and I sincerely appreciate the information provided by those members who have contributed. I thought it best to clarify that, before punkin threatened to place my photo on his "LEGENDARY THREAD" bobbin. :roflmao:

Another contributing factor in my interest, is a collection of 3" fittings I obtained at a very reasonable cost. I will be using 3" for the column, well.... more than likely columns. :D

At Harry's request, I have posted my question here, where it can "be for the benefit it can provide to others".

Harry: Your suggestion for an insert would save me the cost of purchasing reducers and smaller tee's. My confusion now revolves around the insert itself. If I reduced the 3" tee as outlined in your drawing, would the vapor acceleration be as efficient as it would be if I used reducers? I guess with the reducers I "see" a funneling effect to start the vapor acceleration. I would be reducing the 3" to 1 1/2" at the takeoff, and it would go back to 3" above the tee to the condenser. With the top and bottom flanges reversed, there would be some of the funneling I mentioned, but what about the hole at the takeoff? Or is the funneling I see irrelevant?
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Re: product condensor on VM

Postby snuffy » Sat Sep 26, 2009 10:41 am

A few points about Reynolds numbers, turbulence, vapor speed, etc.

As Harry's picture of the velocity profile of laminar flow in a pipe shows, the problem with laminar flow is the distribution of vapor is not even across the diameter so there is less mass-velocity at the periphery where the takeoff is. Getting the center and the takeoff to have about the same amount of vapor passing by is the goal here, so the takeoff isn't starved in relation to the rest of the cross-section.

Turbulence mixes things up and evens out the distribution of vapor. Increasing velocity does that, but the velocity isn't the point, the mixing is. This is where turbulators come in. By forcing the vapor to move sideways to the direction of flow, the mixing happens without a substantial increase in backpressure.

As Harry pointed out, the combined orifice areas (tightest restriction) in the takeoff (at the valve) and the upper leg of the tee should be approximately equal to the area of the lower leg of the tee and the column below that. They also should be in a ratio of about 10:1 - providing that backpressure isn't playing a role in forcing the vapor into the takeoff. So there is an upper limit on how hard the boiler can be pushing the vapor up the column to the tee -- if you increase the power enough, the boiler pressure starts driving the bus. When going for purity, this means there's a maximum power (somewhere between 900 - 1200W for 2" columns depending on the length, tightness of packing, etc.)

My experiments last December with measuring back pressure of relatively loosely packed copper mesh showed that 3' of packed column created about the same backpressure as a 5/8" orifice in a flat plate at 20 inches / sec fluid velocity. I was using air, but the difference in density and viscosity is small, so the numbers are in the ball park.

So if there is a packed column above the tee, it will act (from the viewpoint of the vapor in the tee) just like there is an orifice right at the top of the tee -- in terms of backpressure. This backpressure will tend to force vapor out the side of the tee and into the takeoff. Additional back pressure will come from the height of the vapor column above the tee.

So there are three separate pressures combining to push vapor out the takeoff:

1) pressure coming up the column from the boiler and proportional to the boiler power and vapor velocity in the lower column.

2) backpressure due to drag in the packing in the upper column.

3) the weight of the vapor in the upper column (alcohol vapor is heavier than air and water vapor is lighter than air, so as the composition of the vapor changes, so will this pressure from weight of vapor is what makes VM self regulating.)

And there is an additional pressure differential:

A) the pressure drop caused by the fall of vapor down to the condenser (somewhere near the top of the condenser, the pressure will be atmospheric because the vapor has condensed). This pressure drop is sometimes called "reverse chimney" or "siphon effect.") It's slight, but still present and needs to be taken into account. In the above rig, the combined height of the upper column and the drop to the atmospheric pressure region of the condenser is about 48" so the total effect is substantial. Harry is right- it's not "suction" per se, rather it is the pressure differential caused by the height between the takeoff and the region in the condenser that is at atmospheric pressure. There's no vaccuum anywhere, but there are differential pressures. I think this has been a conceptual stumbling block for a lot of people.

A picture should help.

Image

Any good experiment produces surprises and last nights surprise came when I was trying to get the absolute minimum takeoff rate. The combined pressures made it very difficult to close the ball valve enough to get a rate below 10 drops per second. As soon as the valve was cracked, product started to flow.

The upshot is that all the pressures are operating from different parameters, but the sum is what determines the output.

To return to the start of all this, these combined pressure at low output rates may not be enough by themselves to drag the richest vapor from the center of the tee and thus the need for a little bit of turbulence to make sure that the vapor heading to the condenser is the same composition and pressure as in the column itself.

The VM rigs that are have low outputs are probably fighting one or more of the effects listed above.
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Re: product condensor on VM

Postby Adverse Effects » Sat Sep 26, 2009 7:54 pm

snuffy wrote:Image

:roflmao: :roflmao: :roflmao: :roflmao: :roflmao:

Snffy has run out of head room AGAIN !!!!!
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Re: product condensor on VM

Postby snuffy » Sun Sep 27, 2009 10:06 am

Actually, I still had three inches before I hit the roof. :roflmao:

The upper 36" section was too tall. The excessive combined pressure from the height and the backpressure from the packing overpressurized the tee. It was producing too much output with the valve barely cracked. Yesterday, the upper section was reduced to 24" and the heads compression and range of control both improved dramatically. It also peaked at around 94.5% abv (which indicates I'm running too hard for azeotrope.) With the taller upper section it was peaking around 93%.

This rig also has two reflux collars at 12" and 24" above the boiler.

The charge was the strippings from 30 gallons of sugar wash. Without the heads reservoir: 5.25 quarts of heads; with the 36" upper section and reservoir: 2.5 quarts of heads; with the 24" upper section and the reservoir: 1.5 quarts of heads. Total volume of the stripping run is around 12 quarts (heads, hearts and tails with an average %abv of 93.5 for the hearts - heads were a little higher.) I stopped the run about half way through yesterday and will finish it up today. the best setting is 1100 W and the valve at 30 degrees. This gives an indicated mid-column temperature of 78.56 S (uncalibrated but close to C).

And now I've got 15" of clear space under the roof....

So this little experiment demonstrates that the packed column height above the tee is a critical dimension: too much and the vapor weight gets swamped by the boiler pressure so the takeoff will have too much vapor from the lower column and not enough from the reflux section, thereby lowering the %abv and making it hard to control because there's too much pressure at the tee. Running at less power to the boiler would correct the problem, but with considerably lower output.

This was confirmed by closing the valve, letting the column equalize and briefly getting a higher %abv on opening the valve. After a short time, the %abv would start dropping and the temperature at the middle of the lower column would creep upwards a bit. Because of the overpressure, the ball valve was barely cracked open - just a few degrees past the closed position. Even then, there was almost too much output.

the next phase will experiment with reservoir capacity and number/placement of reflux collars.
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Re: product condensor on VM

Postby Moon Masterson » Sun Sep 27, 2009 6:19 pm

snuffy,

Guess I better take this a few concepts at a time. Let's see if I have this somewhere close to right. Laminar flow has the vapor moving in (layers?), with the vapor closest to the sides of the pipe moving slower than those in the center. As it hits the reduction, the vapor speeds up, but relative to how it was moving to begin with. (Center still moving faster than the sides.) So... the acceleration by itself, does not allow for a proper mixing of the vapors without creating additional turbulence. In addition to the acceleration provided by the restriction, and the generation of additional turbulence, it appears to be necessary to create a slight back pressure above the tee, to create even distribution between the takeoff and the vertical path to the reflux condenser.


Do you have a thread explaining the function of the reflux collars?


I think I have a better understanding of whats going on in the upper section of the reflux condenser now. Before I understood it only as the phenomenon that kept the pressure from increasing in the column. Now I see it as kind of a void as well, that would have an effect on the "pressure" above the takeoff tee.

I'm looking forward to your followup experiments. Thanks for your informative post.
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