Using HERMS Coil to Heat Boiler

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Flavor Trave
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Using HERMS Coil to Heat Boiler

Post by Flavor Trave »

So I’ve recently had this idea of trying to heat a boiler by circulating hot water through a HERMS coil that is submerged in the still boiler.

My thought would be having a keg next to the still pot filled with near/boiling water that i could then pump through the coil in the still pot and then back into the keg. Has anyone tried this? I know larger distilleries used immersed coils pumping steam or propylene glycol to heat their stills. Would boiling water provide enough heat to heat a 20 gallon wash in a 25 gallon boiler? I guess I could always pony up the money for some propylene glycol to raise the boiling point, but ideally would just want to use water.

Now, if anyone has done this, what would be the expected heat up time for a 26 gallon pot using a coil like this: https://www.homebrewing.org/Large-HERMS ... IAQAvD_BwE

Thanks I’m advance for humoring my late night still design thoughts.
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Re: Using HERMS Coil to Heat Boiler

Post by Berserk »

I have not done this myself, so this is from a purely speculative theoretical viewpoint.

If you use just water heating the boiler will be slower and slower. The bigger the difference in temperature between your heating medium and your boiler contents the more efficiently it will transfer heat. At the end of a run when you approach the boiling point of water it will probably be very ineffective.

The difference in temperature is probably why distilleries use glycol or steam (especially pressurised steam), since they can keep it high throughout the run. I would advise against using pressurised steam though, since that's a lot of energy to play around with on a hobby level.

Does that make sense? :)
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still_stirrin
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Re: Using HERMS Coil to Heat Boiler

Post by still_stirrin »

Flavor Trave,

There are a few members here who use steam to heat a mash tun, or even to heat a “thumper boiler”. Steam carries a lot of energy that can transfer to a wash to get it hot. But as Berserk noted, the heat transfer from the steam to the wash is proportional to the temperature difference between the two fluids. So, you always need a higher temperature in the fluid that is transferring the heat from...towards the fluid that is receiving the heat.

Glycol systems are fantastic for cooling fermenters as used in commercial lager breweries. But glycol is not the best fluid when trying to boil a wash, or even a low wines charge in a boiler. The heat capacity and marginal temperature differences simply won’t give you enough energy transfer to boil the wash effectively. You’ll spend more money on pumping the glycol than you would on simply putting an electric element inside the boiler.

If you want to look at steam heat, there is a forum with much discussion on direct injection as well as bain-marie heated boilers. But, typically the systems used by us hobbiests is “atmospheric”, or near-atmospheric for safety’s sake, because as noted, steam under pressure can be very dangerous because of the energy in the steam.

So, read a while in the Steam forum and see what you can learn.
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Re: Using HERMS Coil to Heat Boiler

Post by Butch27 »

You would need a very, very long large diameter coil to make it work with hot water. It may work so so at the start of the run when the boiling temperature of your still charge is relatively low but nearer the end of the run the process would slow significantly and I would anticipate you uttering some not so nice words at that point. You would have to have the water boiling or on the verge of boiling to have it work at all and then you may as well use atmospheric pressure steam. To make full use of the energy in the steam you have to condense it. This still means you need a large coil.
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Re: Using HERMS Coil to Heat Boiler

Post by Flavor Trave »

Thanks for all the info so far. Makes sense with water not being the best idea.

If using steam at atmospheric pressure wouldn’t it only be marginally above the temp of boiling water? Having a pressurized system is where you can gain temp with steam. I read somewhere that a 50/50 mix of water and food grade propylene glycol will have a BP up near 250 degrees F. So if I had my keg filled w/ 5 gallons of propylene glycol and 5 gallons of water, using my March pump (mag drive) to circulate through the coil, could that possibly work? March pump is rated up to 250 degrees. You could have a good 40 degree temp difference toward the end of a run that way. I usually don’t run anything past 205 degrees.

Would keep the keg with the “heat transfer fluid” open at the top, so there is no pressure buildup (could possibly fit the top of the keg with a TC pressure release valve). Could control the flow rate with a ball valve on the output of the March pump. Anyone know how long a 50/50 propylene glycol/ water mix could be reused? Would it beak down over time?

My end goal would be the ability to distill on the grain. I’ve scorched wayyyy to many batches using an electric heating element even with clarified washes. Have been stripping in a propane heated keg pot still and then doing spirit runs in my 8 gallon electric heated milk can still. Making all grain batches draining the wort of the grain like I’m making a beer.
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Re: Using HERMS Coil to Heat Boiler

Post by still_stirrin »

So, if you’re planning to use 50/50 propylene glycol and water, the boiling point is actually about 222*F according to the attached document. While it is greater than water, it is a lot closer to the wash temperature than initially planned. And the heat transfer rate (and vapor production rate) will slow down as the wash temperature approaches the boiling point (obviously).

See attached document.
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Dynalene-PG-engineering-guide.pdf
Propylene Glycol Engineering Data
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Re: Using HERMS Coil to Heat Boiler

Post by BlackStrap »

If you want to look at steam heat, there is a forum with much discussion on direct injection as well as bain-marie heated boilers. But, typically the systems used by us hobbiests is “atmospheric”, or near-atmospheric for safety’s sake, because as noted, steam under pressure can be very dangerous because of the energy in the steam.
+1 SS

Flavor Trave Here's a link to a post in these forums if you interested in what still_stirrin is talking about. There are others similar setups by other members here as well. https://homedistiller.org/forum/viewtop ... 92&t=60248

I also use a HERMs system, but I find that the HERMs coil is more useful holding temp when connected to a PID to make a wort. Now the old worm chiller did double duty as a distillate condenser and as a wort chiller.

It's good to think outside the box, and if the idea has not been done before, and is "safe" to do. This group will encourage you to try and report back...
Most questions can be answered here http://homedistiller.org/ and here http://homedistiller.org/forum/viewforum.php?f=46

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Re: Using HERMS Coil to Heat Boiler

Post by Butch27 »

still_stirrin wrote: Sun Apr 11, 2021 1:07 pm ....the boiling point is actually about 222*F according to the attached document. .....
With a large enough coil 222°F has potential to work. I have always use atmospheric pressure steam and it works but gets real slow at the end and I do believe I may be leaving some alcohol behind. I could probably use a larger coil.
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Re: Using HERMS Coil to Heat Boiler

Post by Flavor Trave »

Thanks for that document. That’s helpful. I wonder if you capped the keg with one of these 2” TC pressure valves and had mild pressure in the system would that get you to 250 degree F BP.

Image

That one is 1.5 bar or 21 PSI and kegs are rated to 60 PSI I believe. Online calculator I found puts the BP of water at 21 PSI at 230 degrees F. I would imagine that would get the h2O propylene glycol solution near 250. Would need to make sure any fittings and piping are rated to that PSI.

Thoughts on that??
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Re: Using HERMS Coil to Heat Boiler

Post by Butch27 »

As a licensed steam engineer I would never condone the use of pressurized steam by novices. There is just too much that can go wrong. Yes you may just be circulating the fluid but if there is pressure in the vessel, there is pressurized steam in the vessel. Our community can not afford an accident that could potentially injure or kill someone.
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Re: Using HERMS Coil to Heat Boiler

Post by Flavor Trave »

Deal, no closed system 😎

That being said, Dow makes a food safe propylene glycol with a BP of 250 degrees F. https://www.dow.com/en-us/pdp.dowfrost- ... 3545z.html

Would there be any drawbacks to running 100% propylene glycol in the system vs a mix with H2O? Other than cost 😬

And do we think that circulating a 240 degree liquid would even be sufficient?
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Re: Using HERMS Coil to Heat Boiler

Post by LWTCS »

240 degrees would certainly work.
Though not as optimally as steam at 1 bar (14.5038 psi or 249.7 degrees F).

Most here are very cautious about the use of steam. As 3 psi will burn you but good. A really good burn mind you.

But to keep things in some sort of context with respect to what is easily/ safely doeable,,,a childs bicycle tire holds 20psi.
You'll need at least a 2 mm wall thickness to run low pressure steam.
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Re: Using HERMS Coil to Heat Boiler

Post by Flavor Trave »

Yea. I’m not looking to go crazy with any pressurization. I had a thumper back up once and build pressure. That was enough for me. I like to stick to my trusty old pot still 😁
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Re: Using HERMS Coil to Heat Boiler

Post by Butch27 »

LWTCS wrote: Sun Apr 11, 2021 2:42 pm ..... But to keep things in some sort of context with respect to what is easily/ safely doeable,,,a childs bicycle tire holds 20psi.
You'll need at least a 2 mm wall thickness to run low pressure steam.
I would suggest that this is a somewhat cavalier attitude to the use of pressurized steam. This is not about what happens when everything goes right, it is about what can happen when things go horribly wrong. What happens when the operator becomes inattentive and allows the pressure become dangerously high with a less than adequate PRV installed? What happens when the operator does not know what they are doing and perhaps floods a red hot crown sheet? What happens when the system is incorrectly engineered?

I posted a couple videos in another thread that I will repost here. I believe these boilers were correctly engineered and maintained and run by licensed operators. However I believe operator error produced catastrophic results. I will repost those videos here.

.
[utube][/utube]



[utube][/utube]



Ok, I have said my piece on this and since the Mods are not promoting safety on this one, I am done preaching about it as well. Have at it. Fill your boots.
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Re: Using HERMS Coil to Heat Boiler

Post by LWTCS »

Butch,,, no need to include the rest of the moderators in your response. My response is my own.
No doubt you are correct in your caution. As mentioned 3 psi can create a very bad burn. Never even mind 15 psi (low pressure) steam. Or your high pressure examples.

However, dealing with low pressure steam (15 psi or below) is just as risky as dealing with 220 volt electricity.

There is no doubt that some edification is requisite prior to fooling with steam. Similarly, some edification is requisite prior to fooling with electricity and high proof vaporized alcohol.

As mentioned, 2mm wall thickness is completely adequate for low pressure steam at 1 bar.
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Re: Using HERMS Coil to Heat Boiler

Post by LWTCS »

And to be clear, the Silver Trail accident did not involve a steam fired (jacketed or coil) kettle. It was a single wall kettle. Very similar to what most everyone here runs.

I do not mean to come over as dismissive of the danger of steam. However, there are certainly other elements of this hobby that are equally dangerous and equally as safe as steam.

Low pressure steam is used every day by some pretty inexperienced operators. Fact, I'd bet money that a 3 psi pressure cooker in granny's kitchen has injured more people than steam fired distillation kettles. And dont even get me started on back yard propane burners and deep fat frying frozen turkeys on Thanksgiving day.......
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Re: Using HERMS Coil to Heat Boiler

Post by hopwhisperer »

I thought about this as well, but the steam is what stopped me. I was a milk pasteurizer for 17 years I'm now an industrial maintenance mechanic there. Ok back on topic, I did UHT for awhile where we heated the milk to 290 F and have to keep 56lbs of pressure on both side to keep it from flashing off. Once it enters the flash chamber(I got into a spirited discussion with one of the engineers that I could turn it into a still) once the pressure is taken off It flashes off and actually goes through an atmospheric change instantly. I could talk for days but finally what I'm trying to say is you would need a pressure vessel once to get to boiling temps and a way to apply pressure to keep it in phase(liquid) while going through the Herms coils.
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Re: Using HERMS Coil to Heat Boiler

Post by hopwhisperer »

Butch27 wrote: Sun Apr 11, 2021 2:07 pm As a licensed steam engineer I would never condone the use of pressurized steam by novices. There is just too much that can go wrong. Yes you may just be circulating the fluid but if there is pressure in the vessel, there is pressurized steam in the vessel. Our community can not afford an accident that could potentially injure or kill someone.
+1 and Yurp pressurized steam is violent
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