Oil Jacketed to Steam Jacketed conversion.. thoughts?

[Bearpig]

I'm using an oil-jacketed boiler I designed long before I started frequenting HD, so go easy on me, there are a few things I'd do differently now.
Until now I've run exclusively fruit brandy and grappa which greatly benefits from a jacketed boiler to keep things from burning.
It's a simple enough design. There's a jacket running about 2/3 of the way up the boiler which is filled with 10 liters of oil. Some people fill theirs with expensive heat transfer oil, I've only ever used refined sunflower oil and never had any problems, as long as I keep the burner reasonable and there's enough liquid in the boiler it never gets close to it's smoke point of 450 F.

Perhaps the reason I haven't had issues with the sunflower oil is because if the boiler is going to sit unused for more than a few weeks I'll drain all the oil out of it, wash out the jacket with a cold grease remover and rinse it thoroughly. The used oil gets stored in 2 liter Coke bottles and replaced about once a year. The only drawback I've found with sunflower oil is if I run the burner too hot then it starts to smell like a deep frier, but if you run an oil jacket too hot it defeats the purpose anyway and the must will burn. So a close eye (and nose) has to be kept on the burner to avoid overheating the oil.

There's a 2" tri-clamp at the top, and the entire head comes off by removing 8 bolts and gives me an 8" access opening. Both use PTFE gaskets. There's a 1/2" NPT thermowell with a simple thermometer in the top. Missing from my diagram is a stand that supports it above the burner and allows me to just tip out the contents of the boiler and jacket. The leglike things on the bottom are a collar on the bottom of the still to help retain some of the heat, there's also a shroud around my propane burner.

My neighbor has been advising me to convert the boiler from oil to steam jacketed. He runs a nearly identical boiler, except he has a pressure gauge on the jacket and where my oil fill spout is, he has an adjustable pressure relief valve. His still is brazed copper while mine is TIG-welded stainless steel. He's calculated the amount of water he needs to fill in the jacket (similar to how a standalone radiator works), basically just heats his boiler and the jacket fills with steam which heats his must/pomace, any overpressure is vented safely away by his relief valve and he keeps an eye on pressure with the gauge. He's been using it for over twenty years without incident. It seems like a more efficient (although potentially less safe) design since it's far less maintenance, no consumables (oil, degreaser), absolutely no smell and potentially more stable temperature. Also a lot less labour since draining/cleaning/refilling the oil is a hassle.

So I'm considering threading the fill spout for a pressure relief valve piped in a safe direction, and adding a 1/2" NPT port for a pressure gauge. I figure these modifications are non-destructive since if I decide to stick with oil I can swap the manometer with a long thermometer and benefit from being able to see the oil temp (currently I go by touch/smell/ear).

Any thoughts? I'm not an engineer or a physicist so I thought I'd consult the experts here before I even think about doing anything.
Should I try the conversion or just leave well enough alone? Possible benefits/drawbacks/risks I'm missing?

Cheers

[Bearpig]

I am a commercial distiller running a small compound still with VM. I was a licensed professional mechanical engineer. I avoid steam like the plague. Keep in mind that though steam doesn't explode as in blow up with fire, if pressure builds up it can explode none the less. The steam burns may just be the start. The force of explosion could rip open distillate that could catch fire. The result would be equivalent to a stick of dynamite. Things that can kill, do kill. It's just a matter of how often. Keep steam out of your operation and cut distillate to below 60% ABV ASAP (bekiw 50% is even better) and you keep your operation much safer. Remember, 100 proof evolved from the practice of testing strength of liquor by seeing if it would catch firing powder on fire. For home hobbyists (and for my money craft distillers) it is prudent to avoid accidents that can kill.

DSP-WA-15069

Ehh, this post made me think twice about the whole thing. Forgive my momentary lapse in judgdment.
Sure he's been using a system like this for 20 years, but the next run might be the one where it pops and disfigures or kills him.
Better safe than sorry. The fact that my current setup is much safer than a steam jacket more than offsets the extra time/work/maintenance inherent in it's design.

So I've answered my own question, but I'll leave the post in case anyone has any comments or thoughts.

Cheers

[Samyguy]

Good Thinking Man

[shadylane]

there are a few things I'd do differently now.

That got my attention

[Bearpig]

there are a few things I'd do differently now.

That got my attention

Mostly just in terms of using TC ferrules for everything instead of my oldskool bolt-together flanges (the TC clamp at the top of the column is a very recent addition).
*knock on wood* I managed to avoid most of the pitfalls like plastics, silicone/rubber gaskets, etc just by common sense (I used cork or hemp rope with flour paste, then switched to teflon).

I haven't really seen any jacketed stills on HD (I guess it's a euro thing) but they're quite useful.
This is what grape pomace looks like, and what I primarily distilled until now:

You can run nasty burn-happy crap like that through a jacketed still and it doesn't scorch at all, the main drawback other than the extra consumables/maintenance is it takes longer to come up to temp.
I might try running some corn mash on the grain just to see what happens in terms of flavor. I think the extra time may offset the labor/mess of straining/clearing corn mash.

[LWTCS]

Do you have any idea how thick your inner and outer wall are?

[Bearpig]

Do you have any idea how thick your inner and outer wall are?

Outer and inner walls are 2mm 304 stainless.
Base plate is 3mm.
TIG welded.

[just sayin]

2 & 3 mm stainless TIG welded would make a stout vessel. Your oil jacket works well except for the oil draining, degreasing and annual replacement. I would think the costly heat transfer oil would end up being a cheap one and done over the long haul. We still use an oil filled radiator space heater we bought in the eighties...just sayin'
Nice design be the way, should do distilling on the grain with ease! Thanks for your post.

[shadylane]

That should make a nice rig.
I used 40psi water from the garden hose for pressure testing mine.
The inside bottom made a hell of a noise when it oil canned

[Bearpig]

2 & 3 mm stainless TIG welded would make a stout vessel. Your oil jacket works well except for the oil draining, degreasing and annual replacement. I would think the costly heat transfer oil would end up being a cheap one and done over the long haul. We still use an oil filled radiator space heater we bought in the eighties...just sayin'
Nice design be the way, should do distilling on the grain with ease! Thanks for your post.

Is the stuff in standalone oil filled radiators always heat transfer oil?
If so I have an old half-dead one that weighs at least 60-70kg that I could cannibalize, maybe I can drain out the oil and the dump would be happy to take the empty housing.
Next time I'm at the cottage I'll flip it over and look for some kind of drain plug or access port.
I'm in the Balkans though, so god knows what oil this was ancient thing was filled with. There's a chance it's filled with 50 year old pig fat

[raketemensch]

Man, I want to live in your neighborhood. The few people I’ve talked to about stilling look at me like I’m batshit.

What do you think your gains would be, if safety weren’t an issue, switching to steam?