Cleaning Run and Coil Not Condensing All Vapor

[JollyMon]

Just finished my first cleaning run with vinegar and ran into an issue and wanted some expert advice on how to solve. I am running an nixon stone setup and it doesn't appear that my coil was able to condense all the vapors. First I was wondering if that is common (not to condense all vapors) on water/vinegar cleaning runs (as I have read it reacts differently then an alcoholic mix)? Secondly, If a coil should be able to keep up with all vapors during the cleaning run, would there be any way to solve this without completely making a new coil.

My coil is just basically a coil that was formed around a 1.5" pipe and is about 8" long made out of 1/4" tubing. Pretty simple, I know, but made it before I found this site and those awesome tutorials in the must read section. And I fully realize that this might not be enough. The coil is located in a 3" pipe and my column is made of 1.5". I am heating with an 1300Watt hot plate currently (as winter is keeping me indoors).

I have read packing the condenser with copper/ss mesh is an option that some people use and I have also read/seen people wrap tubing around the outside of the condenser and said that helped. Would there be any advantages/disadvantages to each approach or could both be employed? I thought I read in some post that wrapping tubing around the outside of the condenser wasn't recommended as the cooling might transfer to the column (which I find hard to believe but you guys are the experts). However, what I was envisioning was wrapping another 10' of 1/4 tubing around the outside of the condenser (with the output water), so that it doesn't affect input water temp but would still offer some additional cooling, then stuff the inner part with ss mesh.

Or Would just scrapping what I currently have be advisable and create a new coil?

[Usge]

Hey Jollyman....

Yes...running water/boil is happening at higher temps and usually done under more heat/pressure and therefore puts a larger strain on your reflux coil to knock it all down.

And yes too..it sounds like your current reflux coil is perhaps not quite up to snuff. You "can" use copper mesh to wrap your coil and it will help. The question is will that be enough? If the gap between your coil and wall is too large...you are also more prone to blow-by (same if the 'hole' in the middle is too wide).

You can try using a "cold finger" in the middle of your coil. If it were me, I'd redo the coil using 3/8" od on the 1.5" pipe to form a single coil, and then put a 1" cold finger down the middle such that it's end extends/protrudes down. Use copper mesh around outside. That should give you a better fit. Keep the whole thing about the same length as before. From there, adjust cooling by water flow (more water, more cooling, visa versa).

[JollyMon]

Thanks Usge. I will give your suggestions a try. I was really hoping not to have to make a new coil, but if what I have is insufficient guess that's what I have to do. Some questions about the cold finger. how far down can the cold finger extend? Can I extend it all the way to the T to get more cooling? or is that not recommended? Only reason I ask is that I noticed a air chamber (Wrot Pressure Air Chamber 1/2" X 1" X 12") while at Lowes that would be a perfect shell for a cold finger but didn't know if it was wise to have it extend that far. I can always use a 1" pipe (cut to length) with a cap, but after I buy all the parts it will work out to roughly the same price.

Thank you again for your guidance it is much appreciative.

[Usge]

typically, it just extends beyond the end of the coil to form a point/center. The main purpose of this is to "center" the dripping distillate/reflux. You can try putting copper scrubber in the middle cavity and wrapped on outside. Then, do your water experiment again. See if by turning up the water all the way you can knock down the vapor. If that doesn't work, you definitely need to rebuild your reflux condenser/coil.

[JollyMon]

Been a bit busy lately and haven't had time to play with the still. I had success since the last post. I built a .5" diameter cold finger and had it installed, but still was not able to collect all the vapors, even at full stream. Adding some packing helped but didn't seem to completely solve my issue. The real key for me, at least, was turning down the heat once it got up to temperature. I had it cranking at full and never touched it. I know this was a rookie mistake (I know I read that in many posts to turn down the heat) and I don't know why I didn't try that earlier, was probably just too excited or thought that since it was a cleaning run I can run it as hard as possible. But by dialing back the heat, I was able to collect all the vapors and use a lot less water. So now after 4-5 vinegar "cleaning" runs done, I now feel confident that the still can handle alcohol and I wont blow myself up with leaking alcohol vapors.

So onto the sacrificial alcohol runs. Thanks Usge for all your advice.

[myles]

The extenal coil on the condenser will work just fine, and might be usefull later if you move your still head onto another column, or use a different heat source. Run it in parallel though. Put a T in both your coolant input and output lines to split the coolant flow.

I am a big fan of coil jacketed condensers as I think they are an easy build. My VM column product condenser is a multi liebig (or should it be called a concentric shotgun? or a hollow coldfinger?), that has concentric vapour paths inside a coil jacketed shell.





EDIT: Forgot to say - a lot of folks heat up on full power and then turn it down.
One setting that is often recommended, is to do a test run with alcohol in the boiler and increase the power untill your still is producing the right combination of vapour and reflux to flood the column. You should be able to hear it when it occurs.
Make a note of the power setting and in future use 80% of that value as your hearts power. A controller is virtually essential for that degree of control. Stabilise your column at a much lower power to concentrate the heads, bleed them off, turn up the power to your noted (80%) figure, re-stabilise and then start collecting product.