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Stilldragon VM

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Stilldragon VM

Postby DuckofDeath » Thu Apr 04, 2013 1:12 pm

So has anyone made a VM using SD parts? I was thinking of putting my smaller product condenser as my top condenser and adding a take off valve underneath.
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Re: Stilldragon VM

Postby delta H » Thu Apr 04, 2013 3:29 pm

We're going to have one (or at least one configuration, the great thing about modular) that is a VM with mainly SD parts, SD boiler, 4" packed column, using a 4->3 reducer for the take off port (that is where the non-SD parts come in, 3->1 short reducer, 1" short T, 3-piece PTFE ball, 90 elbow to a SD 2" shotgun cond. We'll try the 4" dephlem for the top cond, but since we have a 4->2 reducer and another 2" shotgun in theory we could add more cooling if needed (either, both, etc could be tried). On a boiler this will be tall. The take off assembly is a bit heavy, so we will have this supported by more than the column. Also, I could see that our 1" throat on the take-off (1/2" at the ball) being a bit larger than it could be - could try some very light packing in the horizontal to reduce laminar flow? 4" packed is a lot bigger than I've worked with before, so error and trial.

For the packed section we decided to go with SD TC pipe (4"x20") instead of one big 4-6' pipe; the thought was that with the plates for the bubble caps (we ordered extra plates and gaskets to try) we have a way of re-centering the reflux to minimize channeling effects near the walls. I'm a copper mesh guy, but in principle the plates (with a bit of mesh) could hold rings or other random pack as well. Not 100% sure any of that will work, but reasonably easy to test +/- plates, and regardless the short sections will make packing (and cleaning) easier.

We also have a section of bubblecaps/downcomers that we plan to try in a couple locations, I will be most curious to see what is the best place for that. Since we will be only using this on stripped material, having one low to deal with puke is less of an issue. I have this hypothesis that putting it just below the take-off is either the best place to put it or the worst place to put it, but definitely it is going to be tested above and below the pack.
Last edited by delta H on Thu Apr 04, 2013 5:37 pm, edited 1 time in total.
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Re: Stilldragon VM

Postby delta H » Thu Apr 04, 2013 5:45 pm

Fester-

I tend to think you are correct that a plate above pack will do very little, for the same reason you cite. If it does do anything, I would guess it would be an improvement due not reflux/purification but rather inducing turbulence above the pack, which might help at higher gas flow rates (which shouldn't be an issue if the column was run more carefully) in terms of take-off. It could also help a bit with using too high of a water flow rate in the condenser, forcing the cold reflux to interact/warm a bit before it hits the pack and cools deeper than one would like (and thus increasing the effective length of a poorly run column). ...but in all likelyhood it will do nothing. I wonder how many times I'll have to run each configuration to confirm nothing.
Last edited by delta H on Fri Apr 05, 2013 3:58 am, edited 1 time in total.
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Re: Stilldragon VM

Postby Monty » Fri Apr 05, 2013 12:02 am

DuckofDeath wrote:So has anyone made a VM using SD parts? I was thinking of putting my smaller product condenser as my top condenser and adding a take off valve underneath.


I currently run a 2" that reliably makes 94-95%, albeit quite slowly. I use a baby dephleg as a reflux condenser and it's able to handle the job. I've been thinking of upgrading to a 3", but that's a few months down the road. For packing, I use a combination of copper mesh and SS scrubbers. I'll post pics once I set it back up.
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Re: Stilldragon VM

Postby FullySilenced » Fri Apr 05, 2013 12:24 am

Minime has been doing that ss roll packing research... which might be applicable to this unit... especially with restricted heights...
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Re: Stilldragon VM

Postby FullySilenced » Fri Apr 05, 2013 12:42 am

For testing couldn't you drill a hole in the reducing tee and use a cork with the probe till prototyping is finished...
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Re: Stilldragon VM

Postby Monty » Fri Apr 05, 2013 12:47 am

minime wrote:one 2"TC end cap X 1"MPT (top of reflux condenser for vapor lock)


I used a regular end cap and just drilled a 3/16" hole it.
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Re: Stilldragon VM

Postby DrWho » Fri Apr 05, 2013 3:44 am

Fester wrote:I'm really debating on having a SS plate with lots of 5mm holes (since the SPP will be 6mm) welded to one end of the pipe. Screen gaskets are in the development stage and although we will absolutely kill any competition with price, the samples I've received so far are not pretty.


A flat screen will cause the SPP to flood (BTDT, even using a very fine wire with large openings). See the pictures I posted in this thread:

viewtopic.php?f=19&t=211&start=20

The mesh cones are required to prevent flooding. It offers much more space for the falling liquid and rising vapors to pass each other.

???
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Re: Stilldragon VM

Postby delta H » Fri Apr 05, 2013 8:33 am

Fester wrote:Yikes, DeltaH!!!
I just read your welcome thread and now I feel really silly by telling you how to do a simple experiment.

And what is a "3-piece PTFE ball"?


Fester - agreed on how to test, one variable at a time. 3-piece ball valves are pretty standard, I'm sure you have seen ( or own) one, they are rather poorly named, since each is really 3 metal housing pieces, 2 PTFE seats, and a PTFE ball, typically held together with 4 bolts. Like this:

http://www.swagelok.com/search/find_pro ... S-62TS6-JL

Overkill in terms of pressure rating, but I like that the ball twist tension is easy to adjust. Less easy to clean than the other type of PTFE ball.
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Re: Stilldragon VM

Postby Monty » Fri Apr 05, 2013 11:13 am

minime wrote:Actually you don't need a cap at all. It's really no different than a reflux coil.


With a baby dephleg (and a turbulator), you do need a cap to give the vapor enough time to condense. I tried running without a cap first, then with a cap, but without a seal, and thrn I finally settled on drilling a hole in the cap and using a gasket. I'm sure with a more substantial reflux condenser, you could get away without any cap.

My plan is to eventually use the 4" dephleg on top of the 2x2x2 T on top of a 3" packed column, with a 2" ball valve.
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Re: Stilldragon VM

Postby delta H » Sun Apr 07, 2013 8:27 am

Data dependant decision making; I love it.

I wonder if any physically similar copper wool is available. Has anyone tried electroplating copper onto stainless wool/mesh? If it worked would it be thick enough to last long enough for the trouble?
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