Still design feedback

[Cmfb]

I've been doing my reading/research on here and believe I'm ready to start building a still. I'm hoping to get a little feedback from some of the more seasoned members on here.

I'll be building a boiler from a 15.5 gallon keg. I plan to make it modular so I can adjust as needed. Being new to this, I just plan on using it as potstill, but since I can get 90% the parts for free off the job (just may take a while to come across the right parts), I went ahead and drew up the LM/VM hybrid I'd like to have once I get a little more experienced, so I can start collecting parts.

The boiler will be powered by a 5500w element. It'll have a 3" copper riser/column. It will be made from 2- 30" sections with Triclamp connections. I'll use a 30" section with the potstill head and shotgun condenser for potstill mode. I'll use all 60" packed with either SS scrubbers or marbles along with the combo head and shotgun condenser for reflux mode. All will be insulated with armaflex insulation. Thickness will be dependent on what I can barter for on the job, but probably 1/2" or 3/4".

I did have a few questions as well.

1. As designed it will overflow the cup to send the liquid back to the packing material. I've also seen this style designed with a reflux return via a copper tube on the outside of the column. Has anyone had any experience with one vs the other? I couldn't find anything in my searches to indicate any gains by one vs the other.

2. How far above the copper plate that directs liquid into the cup should the bottom of the reflux condenser be? Again, I couldn't find any hard numbers or ratios in my searches, but I figured you wanted some space. I tentatively have it at 1.5 times pipe diameter.

I appreciate any feedback. If my questions have been answered somewhere else, please point me in the right direction. I might just be searching with the wrong terms.

[OtisT]

Hi CMFB. Nice design. I love a good build thread so I looked this over and have Some feedback for you. Just one opinion of many.

Boiler. If you are having it made, consider adding a threaded port for a PRV on the top. I don’t think you need the upper thermometer for vapor temp in the boiler.

Reflux condenser. I don’t see a problem placing that coil closer to the plate. Just don’t let them touch.

Copper plate. Don’t make that copper plate too big. Needs adequate vapor flow around the plate. I’m not sure what the right area for vapor flow around the plate is, but I would guess you want it equal to or greater than the area of the 2” column so your not adding pressure in the head.

Vapor temp. I would recommend a thermometer in your head somewhere. You want to know vapor temp. The thermometer sensor needs to be protected from falling liquid reflux.

VM port and liquid reflux. Liquid reflux will run down the walls of your 2” head. You don’t want the liquid reflux getting into the 1” VM part of the Tee. Can you figure a way to prevent that?

Vent. I think the vent should be bigger. Maybe 1/2” or more. Just imagine 5500w of hot vapor coming through that.

Otis

[Cmfb]

Otis, thanks for the reply!

Hi CMFB. Nice design. I love a good build thread so I looked this over and have Some feedback for you. Just one opinion of many.

Boiler. If you are having it made, consider adding a threaded port for a PRV on the top. I don’t think you need the upper thermometer for vapor temp in the boiler. I'll be doing the modifications myself, so adding that won't be an issue. As for the upper temp sensor, I have a bunch of thermowells from work, so I just threw it in. I figure with it being my first still, I just want to watch everything just for the heck of it.

Reflux condenser. I don’t see a problem placing that coil closer to the plate. Just don’t let them touch. Awesome. I'll lower it a little.

Copper plate. Don’t make that copper plate too big. Needs adequate vapor flow around the plate. I’m not sure what the right area for vapor flow around the plate is, but I would guess you want it equal to or greater than the area of the 2” column so your not adding pressure in the head. That makes sense.

Vapor temp. I would recommend a thermometer in your head somewhere. You want to know vapor temp. The thermometer sensor needs to be protected from falling liquid reflux. I've attached a pic with location.

VM port and liquid reflux. Liquid reflux will run down the walls of your 2” head. You don’t want the liquid reflux getting into the 1” VM part of the Tee. Can you figure a way to prevent that? I hadn't seen anything on the other designs like this. Maybe I can put a little arch over the opening. Just enough to divert the liquid around the opening. Or it might be a good reason to divert the reflux to the outside and back in below the vapor takeoff.

Vent. I think the vent should be bigger. Maybe 1/2” or more. Just imagine 5500w of hot vapor coming through that. I'll adjust that.

Otis

Thanks again for the feedback!

[The Baker]

Have you thought of setting up the keg 'upside down'; and using the existing fitting to attach a modular drain?

Geoff

[Setsumi]

Put the VM on top of the LM. The initial theory was that you use LM for fores and heads and VM for hearts. If the VM is on top you do not contaminate your VM head.... that was the theory.

Outside return of LM, look at RLM, reverse LM. It works but is just something more to fidle with.

StillStiring runs a VMLM head, he may give better ideas. Myself would stick with only one.

[Yummyrum]

Looks similar to mine except I used external Reflux return line with the intention of using RLM later , but never did .
I think your plan will work well .
viewtopic.php?p=7481508#p7481508

[Cmfb]

Have you thought of setting up the keg 'upside down'; and using the existing fitting to attach a modular drain?

Geoff

I have, but I decided I'd like to keep the handles. I plan on putting legs/wheels on the keg. I just haven't lovked down exactly how I want to do it yet.

[Cmfb]

Put the VM on top of the LM. The initial theory was that you use LM for fores and heads and VM for hearts. If the VM is on top you do not contaminate your VM head.... that was the theory.

Outside return of LM, look at RLM, reverse LM. It works but is just something more to fidle with.

StillStiring runs a VMLM head, he may give better ideas. Myself would stick with only one.

I'll look into that. I haven't seen one reversed. I didn't realize that was a thing.

[Cmfb]

Looks similar to mine except I used external Reflux return line with the intention of using RLM later , but never did .
I think your plan will work well .
viewtopic.php?p=7481508#p7481508

Yours is one of the ones I looked at while designing it. How do you like Yours? Is there anything you would change about it? How big of a vent hole did you use on the top of the reflux condenser?

[Yummyrum]

Vent is a short stub of 3/8” , but a hole would do just as well .

I think maybe the only thing I might do is use a smaller valve . When I made mine , VM’s were kinda new and the bent at the time seemed to be about going for minimum Reflux ratio , hence the reducer to a smaller size and affordable valve .

But the reality is that such a still is really only used as a reflux still to make Neutral or Vodka and the whole premiss of a Low Reflux ratio is a pointless goal .

So while I can open the valve fully and have a 1:1 RR , I’ve never needed it nor used it …… the practical downside of this is that where I do run it , it’s barely just a cracked open valve and a bit touchy to control .

The answer to your question on what would I change , is I’d use a smaller size valve so I had more , (less finicky ) control .

Other than that , I wouldn’t give up my windows . St a glance I can see the amount of reflux that is falling .

I can also see when it’s starting to flood and I need to turn down the power
.
And I never use the LM port any more . VM does a better job with less effort and need for constantly tweaking .

[Cmfb]

Vent is a short stub of 3/8” , but a hole would do just as well .

I think maybe the only thing I might do is use a smaller valve . When I made mine , VM’s were kinda new and the bent at the time seemed to be about going for minimum Reflux ratio , hence the reducer to a smaller size and affordable valve .

But the reality is that such a still is really only used as a reflux still to make Neutral or Vodka and the whole premiss of a Low Reflux ratio is a pointless goal .

So while I can open the valve fully and have a 1:1 RR , I’ve never needed it nor used it …… the practical downside of this is that where I do run it , it’s barely just a cracked open valve and a bit touchy to control .

The answer to your question on what would I change , is I’d use a smaller size valve so I had more , (less finicky ) control . That was one of the things I was concerned about. I work for a building/energy automation company. I have one of the engineers looking into what valve would have the most even flow with a vapor. That way I know my adjustments is equal to the output. A lot of valves, especially ball valves and butterfly valves, aren't very good at control. We only use them for on/off applications. For control we mainly use CCV valves, though globe valves are another good valve for control. I'll let you know what I end up with.

Other than that , I wouldn’t give up my windows . St a glance I can see the amount of reflux that is falling . I was looking at those. You might have just convinced me to add a set lol.

I can also see when it’s starting to flood and I need to turn down the power
.
And I never use the LM port any more . VM does a better job with less effort and need for constantly tweaking .

Appreciate your feedback. I'll make sure to let you know when I post the build. It mainly depends on how fast I can barter for the parts lol.

[still_stirrin]

Put the VM on top of the LM. The initial theory was that you use LM for fores and heads and VM for hearts. If the VM is on top you do not contaminate your VM head.... that was the theory.

Outside return of LM, look at RLM, reverse LM. It works but is just something more to fidle with.

StillStiring runs a VMLM head, he may give better ideas. Myself would stick with only one.

I'll look into that. I haven't seen one reversed. I didn't realize that was a thing.

My reflux head is a combination LM/VM (conventional valve, not CCVM). It is a concentric, just like your proposal Cmfb. The LM collection cup is above the VM split.

I NEVER run them simultaneously. I usually start with both valves closed while the column stacks. And then I’ll crack the LM valve open a little to draw off the fores and early heads. For a 10 gallon charge, this is usually only 150-200ml. Then, I’ll close the LM valve, wait a few minutes and crack open the VM valve. Since the VM valve is a 1” ball valve, it doesn’t take much of an opening to start producing.

The proof at the spout will often start at 188-190 proof (94-95% ABV) and go UP after the 1st jar (I collect in 375ml jars). With good reflux, it is common for the proof at the spout to go up to 195-196 proof (96+ %ABV). And the vapor management will hold the proof high until most of the alcohol has been stripped from the boiler.

Once it falls to 165-175 proof (83-88% ABV), I’ll close the VM again and let it re-stack. But by then, I will have collected the majority of my product. Note, that even while the proof at the spout stays high, production will slow to a drip rate and energy costs outdo the value to continue to chase product much further. At that point, I’ll once again crack open the LM valve and the product will quickly fall in purity. Usually, within one last jar (375ml), the proof at the spout will be down below 10%ABV, closer to 5%ABV. Then I shut down the heat and let the system cool down while I start cleanup.

I like the combination reflux head, but the VM does the majority of the (reflux) distilling for me. But, I do run my potstill way more, probably 20 times, or more, to every reflux run. So, if you’re building, plan for the potstill first and add the reflux head when you need it.
ss