shotgun condenser for pot still, need feedback

[greybeard]

I'm sure I'm overthinking this, but I'm just needing some feedback... I am working on a pot still using a keg as the boiler. From everything I understand the height of the column of the pot still is irrelevant. It can be as short as I want/need. Power supply will be electric, but not sure how much yet. Shooting for 5500 in the end. I want to build a 2" shotgun condenser with 4/5 internal pipes, partly because it looks like a fun challenge to construct it think it would work better. The condenser will be vertical. I am estimating 18-20 inches in length based on threads here to cool 5500.

Here's where I need feedback. I want to construct a table around and on top of the keg as a work surface. I am trying to figure out how to make the condenser start high enough and go out from the keg far enough from the keg that it can empty into a container at the height of the top of the keg.

The keg is 8 inches from sanke to side edge. So..... if I use a 20 inch column with a 90 degree curve on top. Attach a cross piece 9 inches long and connect it to the shotgun with another 90 degree curve, can I make a 18-20 inch shotgun hit the level of the top of the keg and land outside the width of the keg.

Does that method make any sense? Other ideas? Can get by with a shorter column, thus less copper?

[ShineonCrazyDiamond]

This is what you want

[greybeard]

I see what you did there. I guess there is a small chance I would like to do neutral spirits in the future. A few things about this though, one I have to have a taller column now which = $$$ in copper. I had considered a modular build that would allow me to do that later. I'll have to think on that.

The other thought, and maybe my theory is wrong, but the taller the column, the further from the heat source, the more potential reflux? And what happens to the alcohol vapor that is in the top part of the T? Reflux?

If my column isn't as tall as the one pictured, then I need to extend my column further out. That way it can be long enough to do the job and not run into my keg.

Just brainstorming. Thanks for the input.

[ShineonCrazyDiamond]

There is no reflux because of column length. It will all exIt through the t. I don't know about you, but I can only get sticks at minimum of 5'. Bottom line is, if you want a vertical shotgun at almost 2' to land at the length of the top of your keg, then there is no way around going to at least 2' in the riser. If you want a lebig, then there are ways to shorten it.

I guess my point is look in that thread and see what my original design was, and how much less copper I used with the new build. Build it right the first time, and that is the best way to save those $$$ in the long run. Even if it is a little more up front.

2' 8" up, 4" for the connection between outlet and 90, then 2' back down for the condenser. Lands on your keg top. The neutral aspect is a secondary benefit that will cost you nothing later.

Just a thought, and only one way to think about it. Lots of other great build around.

[greybeard]

It’s a great build and I have some thinking to do. Certainly worth consideration and the kind of input I was looking for. I have attached an “artistic” rendering of the design I had in mind with the table. Adding some storage, a place to mount temperature gauge and a way to tuck some wires and things away. Not to scale and I’m not responsible for any harm or damage created by this design.

Oh and by the way, you can by copper by the inch on EBay. Any length you want.

[zapata]

Why not mount your shotty at an angle? It will be more efficient, and make it easier to hit your collection height goal. Usually done just by building like your drawing but using a shorter horizontal piece with a triclamp in it. The clamp can pivot to any angle desired, and thus any height desired.

[ShineonCrazyDiamond]

Huh. Explain to me why a shotty is more efficient at an angle?

[still_stirrin]

Why not mount your shotty at an angle? It will be more efficient...

Well, not really.

A shotgun condenser has multiple vapor tubes which typically have a greater vapor flow area than a single vapor tube as used in a Liebig, especially a 3/4" over 1/2" Liebig. Suppose the shotgun has 4 x 1/2" ID tubes, that's 4 x pi x (ID/2) x (ID/2), or 4 x 3.14159 x (.5/2) x (.5/2) = 0.785 sq.in. A 1/2" ID tube is only 0.196 sq.in., only 1/4 the flow area. This results in a faster vapor speed and equates to a shorter dwell time in the condenser.

Also, heat transfer efficiency is a function of the conducting surface area through which the heat is transferred, that is, the walls of the vapor tubes in contact with both the hot vapors and the cold coolant. More tubes gives more surface area, as in the above example, 4 times the surface area for the same length of condenser.

Orientation does affect the condenser in that the vapors have a buoyancy. If the shotgun is vertical as recommended, the vapors will flow uniformly into all the vapor tubes. That distributes the hot vapors equally into the tubes so that they can (equally) remove the heat and induce condensation. If the shotgun is oriented other than vertically, the natural buoyancy of the vapors with tend to distribute unequally and you'll lose performance efficiency...how much is speculative and would have to be measured accurately (it depends on the operating temperatures, the vapor viscosity and its mass).

The bottomline here is that a shotgun condenser can be shorter in length than a Liebig and still function properly. Also, is should be oriented vertically. A Liebig, on the other hand, can and should be oriented on a slant...again, with the intent of increasing the dwell time inside the vapor tube.

Analytically, efficiency is the ability to transfer heat from the hot side to the cold side effectively without excessive geometry (condenser size/material cost) or coolant flowrate (pumping costs).
ss

[LWTCS]

Orientation does affect the condenser in that the vapors have a buoyancy. If the shotgun is vertical as recommended, the vapors will flow uniformly into all the vapor tubes. That distributes the hot vapors equally into the tubes so that they can (equally) remove the heat and induce condensation. If the shotgun is oriented other than vertically, the natural buoyancy of the vapors with tend to distribute unequally and you'll lose performance efficiency...how much is speculative and would have to be measured accurately (it depends on the operating temperatures, the vapor viscosity and its mass).

This^^^

Though it is true that some do orient their shotguns on an angle. They are likely driving their systems accordingly so as to not overwhelm one assumes? Though they are not getting optimal performance. Maybe they don't need optimal?
A pair of 90 degree bends joined at the lyne arm,,,kinda like a hinge,,will allow the user to adjust the angle.

[zapata]

In terms of cooling below the boiling point, an angle is more efficient. A vertical condenser allows droplets to fall without being in contact with the walls, or in less contact. I think there is a chapter or 2 on modeling it in The Heat Exchange Handbook, but I doubt its worth doing the math on, especially in this case where I mentioned it as a side note. The main thing here is that a triclamp on the horizontal allows an adjustable angle and thus collection height/location.

[Twisted Brick]

Though it is true that some do orient their shotguns on an angle. They are likely driving their systems accordingly so as to not overwhelm one assumes? Though they are not getting optimal performance. Maybe they don't need optimal?

In the short time I've had my shotgun, I have only run it at close to a 45* angle so I can safely collect away from the boiler. With ample water flow during a full-on strip, the shell only gets hot down to the uppermost baffle, about 3" down. The remaining length (18") remains cold.

With a trickle of water, the entire length of the condenser gets hot once the reservoir water heats up, but no vapor, thankfully.

[LWTCS]

Though it is true that some do orient their shotguns on an angle. They are likely driving their systems accordingly so as to not overwhelm one assumes? Though they are not getting optimal performance. Maybe they don't need optimal?

In the short time I've had my shotgun, I have only run it at close to a 45* angle so I can safely collect away from the boiler. With ample water flow during a full-on strip, the shell only gets hot down to the uppermost baffle, about 3" down. The remaining length (18") remains cold.

With a trickle of water, the entire length of the condenser gets hot once the reservoir water heats up, but no vapor, thankfully.

Sure
Can usually just increase flow rate if needed. Nothing wrong with what your doing.

[greybeard]

Yeah, I had understood that a shotgun does best when placed vertically. I didn't want my collection to occur right next to the column tube. Since I am aiming for a pot still at present and don't need a long column, I am trying to make sure my shotgun is only as long as it needs to be. Any thoughts on an good length for a shotgun running 5500?

[LWTCS]

20 to 24 inches should give you plenty of knock down.

[Twisted Brick]

Thanks Larry,

With regards to vapor pressure/speed as it exits the last 90 and enters the (angled) vapor tubes, is there anything that can be done with power management that would allow me to minimize any buoyancy effect still stirrin mentions? This is for a short 3" riser reducing to 2" prior to entering the condenser.