New to the Still Design thing

[rad14701]

There is no need for a cap on a LM or VM reflux column unless you intend to use it to center then reflux condenser in the top of the column... There are cheaper ways to accomplish the task, however... A cap would require a vent hole...

[Ayay]

Yes, the column must be open to the atmosphere via a vent hole of some sort. Many coils are attached to a cap and hang from it. My coil is supported internally and I don't use a cap. Vapors are like a fog in that they prefer to float as low as possible and do not rise unless more vapors are pushing from below. If for some reason they don't all get condensed (too much heat or not enough coolant), they must have an outlet otherwise pressure will build up and there is no warning of a dangerous situation.

The thermometer needs to be above the top of the packing, in the vapor, and clear of the reflux stream.

How about this?...

The reflux tube will centre the reflux.
The column need not be reduced in diameter, but OK if you already have the bits.
The packing can go almost to the top of the column.
A hat is needed to direct the condensates into the dam.
The condenser coil can be enclosed in a larger tube, or the same size tube as the column. (Condenser enclosure/shroud/tube is not shown).

[crazyk78]

Great Ayay,

Thanks for the sketch.

I might try to incorporate the tube for the overflow in my design.

Tricky part is that the throat will be 1" so putting a tube in there might close up the gap too much for the vapour to go past.

[crazyk78]

Alright...I've done a bit more work and have a few questions.

Will my sketch below be ok?

I have found that I can get a 2 1/2" condenser tube. Is that ok / better?

I will keep the reflux column at 2"

Can someone advise what the red dimension should be? How much reflux fluid should be held in the dam?

What do you think of my thermometer shield also. will that work without impeding the gas flow? It's quite simple to do this.

Thanks heaps guys.

[rad14701]

crazyk78, the height of the throat is what determines how much liquid reflux resides in the reflux cup... On my small scale version of this design I calibrated the cup to hold one ounce of spirits... You don't want too much and you don't want too little... Just make sure the take off port is always totally below the overflow level during reflux...

[Ayay]

CrazyK your design will work. A hat will be an improvement i think? Condensates going straight through and missing the dam may not be a bad idea.
A 3/8" reflux pipe inside a 1" pipe should be OK because the vapors will find their way. It's not a turbine!
There are many places where you can reduce the height if your ceiling is a factor.

crazyk78, the height of the throat is what determines how much liquid reflux resides in the reflux cup... On my small scale version of this design I calibrated the cup to hold one ounce of spirits... You don't want too much and you don't want too little... Just make sure the take off port is always totally below the overflow level during reflux...

Rad, my current thinking is the take-off port and the reflux outlet can be at the same level. Anything not bled-off will go to reflux regardless of their relative levels. My main concern is to keep the dam as small as possible so as to reduce the 'smearing' inside the dam at the crucial transitions between cuts.

[crazyk78]

Thanks guys for the feedback.

Were there any thoughts whether the 2 1/2" condensor pipe will be ok?

I think I will incorporate a hat design type but I have another idea. If it works I'll post a pic for you to see.

If I do use the hat type design of sorts then I will not need to have the shield on my thermometer.

I did write another post asking users what the pros & cons of having the thermometer in the packing or out of the packing. I'm still out on this one.

Thanks again.

[rad14701]

Exactly, Ayay... Keep the volume to a minimum in order to reduce smearing...

I'm actually thinking about purchasing a more precise needle valve because my modified valve still doesn't give me the fine control of reflux that I desire...

[Ayay]

The temperature of the vapors when they are above the packing is the final tally of all that's going on in the column. If the thermometer is inside the packing then it can contact the reflux liquids which are cooler having just come off the condenser, and besides, it won't be the final tally.

[Ayay]

Exactly, Ayay... Keep the volume to a minimum in order to reduce smearing...

I'm actually thinking about purchasing a more precise needle valve because my modified valve still doesn't give me the fine control of reflux that I desire...

I found that the finer the screw thread on the valve spindle the finer the control. A long thin taper on the spindle helps but the thread pitch is half the equation and unfortunately it's seldom specified. Good luck!