Otis’ 4” Column Condenser - RC / Dephlegmator

[OtisT]

Otis’ 4” Column Condenser - RC / Dephlegmator

After a long break from shop work I am finally starting work on my next build project with this RC / Dephlegmator for a 4” modular column. I want a condenser I can run as an RC just above a VM takeoff or just below a large open takeoff as a Dephlegmator, so it will need to be in a 4” spool open on top and bottom.

I want to keep total height to 8” and bought a new 8” tall spool for the body. I am using dual 3/8” copper coils with independent flow. I’ll connect one coil to a full port ball valve and the other to a needle valve for fine tuning.

I am keeping the output flow pipes separate for a few inches so I have a place to touch (or mount a temp sensor) so I can tell cooling water output temp.

Valves
My first challenge was finding valves I like. I found a 3/8” compression attach needle valve. Not full port, but it is cheep and clean for the build. (Full port needle valves are damn expensive). I think this valve will still give me the flow I need, estimated to be around 5 lpm. I use a smaller 1/4” needle valve attached to a 1/4” coil and can get 3.5 lpm through it, so the 3/8” version should get me where I need to be.

I am using a 1/8” full port ball valve, which has a 1/4” full port opening so it is a perfect match for this tubing size. 3/8” OD tubing is also sized perfectly to be threaded for the 1/8” FNPT thread on the valve. Very clean looking. The down side is that any leak or rework needed will be a major repair ordeal.

Threading the 3/8” tubing

Needle and Ball valves, dry fit

[OtisT]

Output side

Here is the cooling output side of the condenser. Nice long tubes for checking individual output water temps before they merge.

Output assembly, dry fit

Output assembly positioned properly

[OtisT]

Dry Fit of the Controls

I taped the input and output sections on the spool to see what it looks like. I wanted easy access to both valves as well as access to both output tubes for temp checks, so I am making everything accessible from the front view.

Input Manifold on the spool

Input Manifold

FYI. The input manifold shown in the pic above is missing the 45deg street elbow.

Output Manifold on the spool

Output Manifold

Front View of the condenser

Front View

[OtisT]

Coils

Two coils for this condenser made of 3/8” copper tubing. I packed the tubes with salt before bending them. A few wrinkles around the I/O but the tube is not kinked and the flow is still good.

The inner coil is 10 winds, 6.5” tall, 1” ID. The outer coil is 8 winds, 6” tall, ID 2 1/4”. I could not make a tight enough bend on the outer coil so I opted to use mini elbows.

The next step is to drill 4 holes in my spool.

Otis

[Twisted Brick]

Gorgeous coils, Otis. I someday hope to be able to make some of those of that quality. Looking forward to seeing the finished dephlegmator.

[Dewstiller]

Really nice! Looks Great.

[Yummyrum]

Bloody top notch work Otis .
Will be keen to see how it performs . I been wanting to make a dual coil in 3/8” for my 4” VM but putting it off . Hope mine turns out half as good as yours . Yours looks amazing

Seems like salts a winner

[Deplorable]

Wow, thats some impressive coil work. Looking forward to updates.
I see the inards of a baffled shotgun in the background as well.

[SassyFrass]

Beautiful work Otis. Very inspirational for an old pot stiller like me, looking to move into the reflux side of stilling. Nice write up too.
SF

[OtisT]

Just got it all together and cleaned up a bit. Still need to do a few leak tests.

Front view

Front view. I wanted to have easy access to both valves and both outputs without having to move at all.

Input controls

Outputs

Coils

View from the back

Back view. I will likely put a 1/2” elbow down on each threaded fitting and run my fluids straight down from there.

Can’t find the darn flow meter, so it may be a while before I get around to testing this. I’m happy I got this far. A few days off goes a long way. Otis

[OtisT]

I see the inards of a baffled shotgun in the background as well.

Yes, that shotgun in the background is another project. I’m using plates from Twisted brick. After a dry fit I had second thoughts on the length, want to make it longer, so I have some more pipe to cut.

[Deplorable]

Interesting. How long do you feel it needs to be for your needs? I couldn't overpower my 20 inch boiling water. Lord knows I tried.

[OtisT]

Deplorable. Well the pipe I cut first was for 14” of jacketed vapor path (16” overall length). With a good flow of cold water I think that would be plenty enough to handle 5500W. I’m having second thoughts only because I can’t find anyone running one this short, most having around 20”+ of vapor path. I’m considering adding just a few inches, to a 16” or possibly 18” VP, to give me a little more breathing room. Final decision on that one is still up in the air.

Otis

[Deplorable]

My water jacket OAL is 21" and 19" vapor tubes. The ferrules I used are 3/4" tall, 7 baffles makes it almost too efficient for a 2 inch pot still, but since I'm not using a closed loop cooling system its nice to keep the water use to a minimum.
The next plan is to start utilizing the discharge water through my wort chiller to preheat my next charge for the still.

[OtisT]

Leak Test
I’m happy that my condenser passed the cooling flow leak test on the first pass.

Flow Rate
The flow rate was way higher than I anticipated at city water pressure. A lot more flow than I should ever need. I think I need to add a pressure regulator to my water manifold.

The outer coil with the ball valve open passes 19 liters/minute (lpm)

The inner coil with the needle valve open full can pass 12 lpm.
1/4 turn = .5 lpm
1/2 turn = 3.2 lpm
3/4 turn = 5.1 lpm
1 turn = 5.6 lpm

Otis

[Deplorable]

Leak Test
I’m happy that my condenser passed the cooling flow leak test on the first pass.

I think I need to add a pressure regulator to my water manifold.

Otis

This is a great idea! Dang, why didn't I think of this?
I have one in my 5th wheel kit. Im going to try this out on my manifold. I can see where cutting the city water pressure in half would help me out.
I guess sometimes you just have to hear someone else say it.

[OtisT]

Leak Test
I’m happy that my condenser passed the cooling flow leak test on the first pass.

I think I need to add a pressure regulator to my water manifold.

Otis

This is a great idea! Dang, why didn't I think of this?
I have one in my 5th wheel kit. Im going to try this out on my manifold. I can see where cutting the city water pressure in half would help me out.
I guess sometimes you just have to hear someone else say it.

Ya, we have really good pressure here and I am regularly springing leaks and blowing hoses off of barbs, even with hose clamps. I’m in the process of setting up a new still room, and updating my manifold by adding a pressure regulator is on my list of to-dos.

Otis

[Prairiepiss]

Ooooo nice copper porn.

[tiramisu]

Just going over this thread again... @OtisT this certainly is a pretty way to do a dephlegmator.
Watched a few videos last night on heat exchangers - fire tube/water tubes.

I admit to really liking the way it looks.
Steam Punk.

A couple of comparison contrast questions for you.
What are the pro's / con's of this design over the more commonly seen tube dephlegmator?
-- efficiency vs speed of temperature change?
-- other?

What are the pro's / con's of the coil dephlegmator with a good valve over a ccvm coil?
-- wider range of reflux?
-- easier/harder to operate?
-- less water required or at least more efficient use?
-- other?

Thanks,
t

tube bending (2014)


shell and heat exchanger engineeering



found this old refrigeration video on making good flare joints
[utube][/utube]

I suspect that cutting a fresh piece of pipe and redoing the flare is a better solution than his solder idea
but it is a nice demo.

[shadylane]

I should have thought about this idea.

threading tubing.jpeg (18.27 KiB) Viewed 3148 times

[OtisT]

Ya Shady, I was pretty happy with the 1/8” threaded connection to the ball valve, but in the end I removed it. After playing with this condenser in my rig I found that I really wanted a needle valve on each coil. I swapped out the ball valve for another compression connect needle valve for fine control on each coil.

Removing the ball valve

Updated with two needle valves

Otis

[Setsumi]

And then some of us can only drool... no, aspire to such building skills. Some copy, others push. You certainly push.

[MidnightThunder]

That condenser is a beauty Otis! Can you supply any figures on how it performed? Perhaps max knockdown power and water usage.

[OtisT]

That condenser is a beauty Otis! Can you supply any figures on how it performed? Perhaps max knockdown power and water usage.

Hi MidnightThunder. I think I will need to take measurements on a future run to give you detailed specifics. I’ve only got some early notes on this and have since been running by senses and not bothering with measurements. I only recorded data from my CM runs, and did not record any data from running this above my VM head. Here is what I do know from my early CM runs:

My max power output is 5500W and this condenser handles that with no problem.

I can knock down 5500w with a flow under 5 lpm. I think it was closer to 4 or 4.5 lpm for 100% reflux. Max flow potential is about 34 lpm.

Either coil independently was able to knock down all 5500w. The inner (smaller) coil required about .5 lpm more flow for the same knockdown. I tested this by seeing how low of a flow would keep any vapor from passing to the Product condenser (PC).

At 3000 watts I set the flow to roughly 1.75 lpm to achieve a reflux ratio around 8 to 1. I think output shut down to the PC at around 2 lpm flow.

Hope this helps ya.
Otis

[tiramisu]

I keep looking at this and going hm. Seems like a project that I might be able to complete. My torch is on order. I have my pound of #8 and acid flux. I have a 4" piece of Sanitary spool in the toy box that I haven't been able to decide what to do with. The rest looks like Home Depot or Canadian tire could handle it. My current reflux condenser is a Gas Line hose and CCVM so an inline closed condenser like this would be a tidy upgrade.

I also have a 5500Watt electric element at 220 so I'm thinking this is a darn good idea.

@OtisT thanks for the write up.

[RC Al]

So, this RC raises an interesting question

Its able to knock down 5500w with just the inner coil, so even with a clear path up between the side and the outer coil, the hot vapour was still attracted to the more restricted colder coil to be condensed?

And or is having a hot coil next to a cooler coil creating a flow effect, cause its working the same with the flows swapped?

Is there an concentric reducer (cone) above it? Perhaps an influence?

[Yummyrum]

So, this RC raises an interesting question

Its able to knock down 5500w with just the inner coil, so even with a clear path up between the side and the outer coil, the hot vapour was still attracted to the more restricted colder coil to be condensed?

And or is having a hot coil next to a cooler coil creating a flow effect, cause its working the same with the flows swapped?

Is there an concentric reducer (cone) above it? Perhaps an influence?

This had got my attention too RC .
Wondering if the adjacent coil is causing turbulence in the space . If the adjacent coil was not there , would it work as effectively ?

[shadylane]

I think turbulence in the vapor decreases a condensers effectiveness.

[Yummyrum]

I think turbulence in the vapor decreases a condensers effectiveness.

Part of me wants to agree with that too Shady .Turbulence reduces dwell time in contact with cool surface .

I’m just curious about the space between the inner coil and the 4”shell . Theres maybe an inch all around . I’d imagine that if there was no outer coil , the vapour going up the sides of the shell would be a laminar flow and likely not get condensed , where as if its swirling around a coil, there’d be more chance of outer vapour coming in contact with cool inner coil .

Hey sorry to go OT otis . But your design and findings are intruging .

[shadylane]

Hey sorry to go OT otis . But your design and findings are intruging .

And beautifully done.

Here's a head scratcher from one of my "what if" experiments.
I put a copper sleeve around but not thermally connected to a coiled dephleg.
And a considerable amount of alcohol vapor condensed and dripped off the sleeve