New concentric-coolant direction ???

[Gatsby]

After much reading here, I'm reconfiguring my still.
7.75 Gal keg
Changing to electric 4500 watt heating, (Tri-clamped)
Control and measuring power from Chinese components
36" X 2" copper column
Alternating copper mesh and SS scrubbies
Sight tube, silicone seals wrapped with teflon tape
2 x 1-1/2 x 1 Concentric LM head all copper
I'm a bit more than halfway there. Tri-clamps throughout.
I also have the major pieces for a potstill head, as well as a VM head.

Last night I got to thinking about the Concentric LM
The 2" is just over 12" long. I spiral wrapped the 1-1/2 with a solid copper wire that is about 75% the size of the space between the tubes, and spot soldered it every 180 degrees. I figure it will help keep some of the coolant water from taking a shortcut from inlet to outlet, and increase the surface area of the inner tube a little.
So now my question:
From all I've read the cooling water should flow counter to the vapor, which would be from top to bottom. But it seams to me that this would create a pocket of air in the coolant chamber.
Am I correct? How do others do it? Comments!
Gatsby

[zach]

I've got a 1 1/2 over 1 1/4 concentric , 16" long with a 1300 watt heater on a 5 gallon boiler. The water inlet is at the top and the outlet on the bottom. I have a wire spiraled in the coolant passage.

I put an endoscope down the condenser during a run. The active area with liquid condensing and draining was in the bottom 2 or 3 inches. The vapor cooling zone, where there was some condensed liquid but nothing draining, looked to be only 2 or 3 inches above that. The upper 10" of the condenser was air.

I believe it will make little difference if the water inlet is on the top or bottom. There will always be air in the top section of the condenser as long as there is cooling water and the condenser is over-sized.

[still_stirrin]

After much reading here, I'm reconfiguring my still.
7.75 Gal keg
Changing to electric 4500 watt heating, (Tri-clamped)
Control and measuring power from Chinese components
36" X 2" copper column
Alternating copper mesh and SS scrubbies <— why do this? Homogenous packing would make a better reflux gradient. I don’t see the advantage to alternating packing.
Sight tube, silicone seals wrapped with teflon tape
2 x 1-1/2 x 1 Concentric LM head all copper <— I used a 2x1-1/2x1-1/2 DWV tee for mine. The outer condenser jacket is 2” while the inner (vapor) jacket is 1-1/2”. That gives me a 1/4” water jacket all around. The vapor tube and inner wall of the liquid collection cup is 1”, again giving me a 1/4” annular liquid collection cup. I advise calculating the volume (height) of the cup so your collected liquid is between 1 and 4 ounces, with the lower number producing less smearing.
I'm a bit more than halfway there. Tri-clamps throughout.
I also have the major pieces for a potstill head, as well as a VM head.

Last night I got to thinking about the Concentric LM
The 2" is just over 12" long. I spiral wrapped the 1-1/2 with a solid copper wire that is about 75% the size of the space between the tubes, and spot soldered it every 180 degrees. I figure it will help keep some of the coolant water from taking a shortcut from inlet to outlet, and increase the surface area of the inner tube a little. <— I used slightly flattened 1/4” soft copper tubing. It fills the gap and I managed to slide it into the annular gap with a little “persuasion”. It is also tack soldered to the inside tube, so it makes a great spiraling swirl for the water to cool the upper condenser. A touch with my hand tells me where the water flow should be by the temperature gradient of the water jacket.
So now my question:
From all I've read the cooling water should flow counter to the vapor, which would be from top to bottom. But it seams to me that this would create a pocket of air in the coolant chamber.
Am I correct? How do others do it? Comments!
Gatsby

What i’ve done is route the hot water outlet (mine is hard piped) up over the cold water inlet at the top of the condenser. This way, the condenser will always be full of water. And the hot water comes out of the condenser at the bottom, closest to the concentric LM cup.

[Gatsby]

Thanks, Zach and SS.
The alternating packing was just a random way of using what I had. I will probably go to SPP or lava after I get to see how it goes this way.
My 1" does extend almost 4" into the 1-1/2" and that gives me between 1 and two ounces puddle.
Your hammered tube does a better job of routing the coolant path. I was afraid of not being able to get it together if I made it too tight.
I too thought of bringing the bottom coolant tube up on the outside to the top, but I'm not convinced that it will eliminate the air. The water is far heavier than the air and it seems to me that the air pocket will remain. That doesn't mean it won't work of course.
Okay; while writing it just occurred to me that a little petcock located high on the outside would allow for bleeding any trapped air. So I will bring the exit tube up, and add a petcock. Got to stay full of water that way.

[still_stirrin]

...I too thought of bringing the bottom coolant tube up on the outside to the top, but I'm not convinced that it will eliminate the air. The water is far heavier than the air and it seems to me that the air pocket will remain. That doesn't mean it won't work of course.

It most certainly does work. I usually fill the water jacket with full water pressure before regulating the flow back. This ensures all (possible) air bubbles are pushed out.

...while writing it just occurred to me that a little petcock located high on the outside would allow for bleeding any trapped air. So I will bring the exit tube up, and add a petcock. Got to stay full of water that way.

You don’t need an air bleed valve. As I said a moment ago...just pre-fill the condenser until you get a steady output flow. Then, you can throttle back the water valve. Incidentally, I have a ball valve on the outlet line, after routing up and over the input that I use to regulate the water flow.

[Gatsby]

Okay, cool, I'll try it.

[StillerBoy]

I run a concentric 2" setup.. my reflux condenser is a 2" x 12" outside shell with the inner tube being 1.5" x 13" in length with 1/4" copper tube inside.. the reason for the inner tube being a bit longer is it provide extra space for the packaging of the scrubby, plus it allows to monitor the temperature during refluxing which I keep it just on the cool side.. I can run it anywhere between 2000w and 2800w with that size of condenser.. as to the inner, it is done in the same manner as described by SS..

Mars

[Gatsby]

Very pretty stuff Mars. My stuff is more along the rat-rod look.
What direction does your coolant flow?
When the parts are assembled do you use any sealant, gasket, paste?
What output rates are you guys getting?

[StillerBoy]

When the parts are assembled do you use any sealant, gasket, paste?

To seal the joins, I use 3/4" teflon tape..

What output rates are you guys getting?

Using a column length of 34", packed with lava rock in 1/4 - 3/8" size, and 2400w of power, once out of the heads, I get 3L plus per hour of 95%

Mars

[Gatsby]

How do you use the tape? Wrap the male part?
Are you using red or gray/black rock? Do you clean the rock often?
Can you describe what that output rate looks like

[Gatsby]

Also Mars, did using lava rock increase your output or purity or both?

[StillerBoy]

How do you use the tape? Wrap the male part?

If you look closely at the extension pipes, you will notice a 1/4" band just up from the end which is position as the same depth as the depth of the coupling.. I put 5 wraps of 3/4" tape, one quarter over lapping the band and twist it on in the opposite that the wrapping is done..

did using lava rock increase your output or purity or both?

When I first started using the concentric, I was using ss scrubbies.. then after some research, I switch over lava rocks.. my purity didn't increase, but, my output (take off rate) increase.. in other words, I could use more power..

The lava rocks are just the one you buy for the BBQ in 10 lbs bags, and spend time breaking them up to size as stated in the previous post.. plus I clean these after each usage by soaking them in hot water for a day or so, then rinsing them out, and allow to dry on an old towel, that if I am not going to be using them the next week..

Mars

[minime]

I run a concentric 2" setup.. my reflux condenser is a 2" x 12" outside shell with the inner tube being 1.5" x 13" in length with 1/4" copper tube inside.. the reason for the inner tube being a bit longer is it provide extra space for the packaging of the scrubby, plus it allows to monitor the temperature during refluxing which I keep it just on the cool side.. I can run it anywhere between 2000w and 2800w with that size of condenser.. as to the inner, it is done in the same manner as described by SS..

Mars

got a first hand look at some of StillerBoy's work today. His soldering skills and workmanship are superb

[zapata]

Off topic, but, minime?! Wow, blast from the past, hope you're doing well!