Size Of Dephleg, advice please.

[YHB]

My VM/LM splitter takes up too much height for my new build, and I have finally decided to replace it with a CM type Dephlegmator .

That was the easy part, now I have to decide on either a coil or shell and multiple tubes.

The question is, for a multiple tube condenser how many tubes what diameter and length would you recommend?. The column is 2.1/2", the boiler is 2.1/2 kW and the material of construction is copper.

Toodlepip.

[law-of-ohms]

try one about 200mm long.

[Myles]

Personally I would do a different calculation for this based on your boiler power.

First question is do you wish the ability to put the column into full reflux? On a bigger column I would recommend to use two condensers but it adds complexity. As this is sub 3kW I would just use a single dephlegmator with the potential for 100% reflux.

I prefer to use 12 mm dia copper tube that is readily available in straight 2m lengths for the vapour tubes, as it is so convenient to work with straight tube. You can use 15 mm but I just prefer the 12 mm.

A 3" copper shell with 9 tubes will easily do the job. 200 mm is more than ample in this configuration so in effect you could build it from a single 2m stick of 12 mm tube. If you wish to go shorter just put more tubes in a bigger shell. I am thinking of a dephlegmator of 150 mm for my own use.

[law-of-ohms]

This would be easy for me to make.

sit your pipe in the recess and solder.

[YHB]

This would be easy for me to make.

sit your pipe in the recess and solder.

That looks a great idea, The first end would be OK, the closing end may be bit more difficult.

How about making the recesses for the smaller tube on the opposite side of the plate to the recess for the shell?

Assembly would be

1) solder the shell end plates.

2) insert the tubes with an excess protruding past the plate.

3) solder the tubes from the outside, using the rebate to keep the solder flush with the end plate.

4) cut the tubes flush with the end plate.

[ShiFu]

3" x 200mm MAY be enough. Never hurts to oversize it a touch. At worst you will just use less cooling water during the run.     
Adding dimples (whack/deform the inner tubes before construction to force the vapor to bounce around) and adding a bit of scrubby strands in the pipes will both add efficiency. 

I also prefer to use larger diameter inner pipes for a dephlegmator as it is easier to tune later.   
Thinner wall copper pipes are harder to solder but are more efficient to knock down the vapors.   

It is, after all, a system. If the dephegmator can't knock down the vapor 100% then you can always decrease the boiler power to achieve that equilibrium, provided you have some sort of power controller.   

Please don't flame me guys, its just my experience that slightly overbuilding the condensers is a good thing. GROSSLY over-sizing a dephlegmator (VS a reflux condenser) requires very high precision valves to control.   
 
Since I'm reading this as... YHB's new bubble plate column build... and not a packed column build, I can only assume he is concerned about a bubble plate still here and now. Bubble plates are easier to knock back than a packed column.  Again, I expect to get flamed here but it is true and I do not know why. Maybe it is the dynamic of a plate fluid bed vs column packing whetting or whatever...  A bubble plate column does Not act like a packed column.     

His column is about 2.5" diameter, right?  And max power at 2.5Kw.  160mm tall with 7 x 16mm tubes in a 2.5" jacket would work great in my opinion. But 2.5" copper is odd to source.  The 2.5" ferrules and clamps for that copper pipe are odd to source too.

Having vended literally thousands of stills does not make me an expert. It only made me good at sourcing parts for stills.   
In my humble opinion, try to get the biggest ID of inner pipes within reason (not more than 3/4" on a still column of less than 6" or more than 1/2" for a 4" still) in a dephlegmator length that is roughly 4 to 6 times the diameter as the column. 
4x will do. 6x will save a lot of water.   
The more excessive the dephlegmator is to the column then the more control (precision needle valves) you will need.   

Needle valves are a one time cost. Excessive water use is an ongoing cost. A few extra bucks in slightly oversizing the dephlegmator will save money long term.   

Just my $1.02 worth.   (2 cents plus long winded reply  )

[ShiFu]

Oops, last post was while others were posting.   


I've often thought of copper dephlegmator and product condenser ends. The biggest problem is not the edge bevel for the clamp as that is standard,   the problem is every country has different size copper pipe.   USA is different than AUS which is different from the UK.   


It is still a very cool idea though.   

[Myles]

Nice idea LOO.
I would favour tubes all the way through and machine them down after soldering also.

At the moment I fit the end plates inside the shell and braze them and the tubes - and then solder the ferrules on the outside of the shell but it takes time.

If you could braze the end plate / ferrules to the shell, and then just solder in the tubes it would make fabrication MUCH easier.

And ShiFu not disagreeing with you I just prefer slightly smaller dia vapour tubes. It is worth remembering though folks the conditions under which you will be running the still. Honestly how many actually put the column into full reflux at max power? Probably not that many.

I favour the initial column stabilisation and heads removal at low power, then re-stabilise at operating power - but that is less than my max power, and that is mostly used on warm up. Also the dephlegmator can be a bit wider than the column to bring the length down. "Square" dephlegmators with height = diameter can be achieved.

[Myles]

Oops, last post was while others were posting.   


I've often thought of copper dephlegmator and product condenser ends. The biggest problem is not the edge bevel for the clamp as that is standard,   the problem is every country has different size copper pipe.   USA is different than AUS which is different from the UK.   


It is still a very cool idea though.

You are absolutely correct. Not a criticism of your gear but I am having some copper ferrules made in Aus that are expanded to fit as a male part inside my UK spec 4.25" dia tube.

Just so I can build a copper shell plated column. Am still using your SGKs with 3" sight glasses and your 2" ferrules that work perfectly with our 54 mm tube and there is a good chance that I may upgrade to one of your boilers later.

[ShiFu]

1) If you are referring to StillDragon actually creating a useful part without me then OK, good.  About damn time.   

Maybe they can finally afford to pay their balance to me?   I doubt it.   They haven't yet after more than a year!   

PLEASE (you send them letters) tell them to pay the $300,000+ USD that they owe to me. They have stopped answering my emails for their overdue payments. What does that tell you about them?       

StillDragon integrity means what?    Nothing but lame excuses.   

2) If other, please specify.   

[Myles]

Definitely No2. Nothing to do with StillDragon.

Emptyglass at CCSC came up with an idea and I asked him to modify it to suit my own requirements for my own personal build, and to suit UK specification tube.

As you said the tube sizes are quite different in various locations. There is some overlap and I really like the brass 2" ferrules so will continue to use those and the 3" versions. Unfortunately the 4" doesn't fit my tube so I made other arrangements.

I am looking forwards to fishmouthing brass 3' ferrules so I cam braze them directly onto my 4.25" tube to use as sight glass ports. For some strange reason (probably because it is difficult) I couldn't find copper 4x4x3 Ts.

Copper column with your bubble caps and probably perforated plates also.

To try and drag this back to the dephlegmator issue - I am going for a  dephlegmator with 150 mm length and 108 mm diameter.

[YHB]

Thanks every one for your input, it sounds just about doable with the left overs that I have.

I think I will be able to squeeze a 180mm long shell out of the 2.1/2" tube and have enough room for 5 x 15mm tubes.

I do not have the luxury of a brazing set up so it will be soft solder all the way, could be lots of fun

Toodlepip

Brian

[Myles]

If you are going to soft solder everything there is one way to do it that makes it easier to solder everything all in 1 action.

You pre solder all the parts individually before assembly. So for example you pre tin the inside of the end plates, pre tin the ends of the tube, and pre tin the inside of the shell. Then adjust everything so it is a tight fit.

When you solder on the end caps you also heat the shell, tube and end plates and everything just flows together.  Off course the tubes will try to fall out but if you have flared them slightly they can't. All this is assuming the end caps are on the outside of the shell.

Its the way I used to put centring cones inside straight end feed connectors.

It is a bit easier though with multi stage soldering. On 2.5" tube you should be able to braze with hand held gas if you use 55% silver solder. Its the lowest melting point of the brazing alloys (that I use) and I use it quite a lot. http://www.cupalloys.co.uk/home/