Closed Loop Boiler

Hi Everybody.

I have been running a 4" dragon for about a year now and would like to invest in a bigger still.

I have Allied Super Hot 500,000 BTU/ Hr closed loop boiler that I would like to use to either be the sole source of heat for the kettle or at the very least assist so I don't need to invest in a steam generator at this point. Or use excessive amounts of electricity as natural gas is much cheaper in my area.

The Boiler can be turned up to 102 C.

I was hoping to buy a Baine Marie Kettle and fill the jacket with propylene glycol.

I was then planning to isolate the rest of the closed loop system from the kettle by using a heat exchanger and a pump to circulate the propylene glycol to exchange with a dedicated closed loop.

Questions.

  1. How big of kettle could I run and or preheat with this close loop boiler?
  2. If I need supplemental heating elements in the propylene glycol, how much wattage would I need?
  3. Has anyone ever attempted something like this before?
  4. Am I out to lunch? And am I overlooking something obvious?

Thanks!

foreshot

Comments

  • edited July 2016

    Hydronic boiler? The problem is that water/glycol is a poor heat transfer medium in comparison to direct immersion elements or steam. While you'll have the power, you won't necessarily have the speed. Adding an additional heat exchanger to the mix is going to slow that even further. What you'd probably find is that the temp increases looked good at first, but the closer you got to the boiler temp, the slower the temp rise would get.

    This has been proposed numerous times, but nobody seems to follow through on whether or not it has been successful. I suspect that while it might work, it would be brutally slow. What would happen is the boiler would heat the fluid up, probably pretty quickly, and then the boiler would shut down, and it would stay there a while, and occasionally fire up again for a minute or two. So while the boiler has the ability to burn 500,000 BTU of gas in an hour, in reality it would be nowhere near that.

  • It would be a pretty expensive trial-and-error kind of test.

  • I would start working backwards.

    What's the kettle size you're looking for?

    How much of a heat mantle does that size have?

    What's the delta T you need to maintain for a run to have enough evaporation?

    Overall, it seems like an inefficient way to heat as you would only benefit during the heat up of your mantle. Once the delta between your mantle and boiler medium is small, the benefit is marginal. Additional, if you push your water/glycol temp past 102C your boiler is starting to cool your mantle unless you isolate the us.

  • I would like a 500 L or a 1000 L boiler with either a 8" or a 12" column.

    No idea on the mantel surface area or the efficiency of the surface area, hopefully someone from still dragon can comment.

    If you convert 500,000 BTU to KW it works out to roughly 145000 W I think this will allow me to bring the was up to temp fairly fast but eventually I will level off and run out of Delta t. At that point I would have to isolate the closed loop system and run the immersion heaters.

    For the guys running 500L or 1000L baine Marie Kettle s how many KW are you throwing at it?

    Inifiecient? I thought it took a massive amount of energy to bring fluid to a boil and a smaller amount to hold it there.

    Thanks

  • edited July 2016

    Is it a dual purpose steam/hydronic boiler? If so, convert it to steam trim.

    We are using 15.6bhp - slightly larger - with 1000 liters. This is steam, which is considerably better at heat transfer than water.

    On a cold day, cold wash, cold boiler, from flipping the switch to distilling might be 1hr15 or 1hr30. Using water? Like 4 or 5 hours probably.

    Give it a try, inquiring minds want to know, maybe it will work.

  • I have thought about using a hydronic boiler that uses cheaper energy to get the mass up in temperature but then switch to direct imersion for control and the extra heat you need. Look how much energy it takes to get a lot of liquid hot . The roiling boil in easy to maintain with electric direct.

  • edited July 2016

    Using the boiler and a heat exchanger to bring oil to temp, before transitioning to elements is an interesting idea.

    But installing a boiler is usually as expensive as a boiler itself. Installing that boiler in a commercial setting might cost 5 grand. What's the ROI on that compared to just going steam?

  • edited July 2016

    From last year on adi- Steam is old school!!!

  • @grim said: Is it a dual purpose steam/hydronic boiler? If so, convert it to steam trim.

    We are using 15.6bhp - slightly larger - with 1000 liters. This is steam, which is considerably better at heat transfer than water.

    On a cold day, cold wash, cold boiler, from flipping the switch to distilling might be 1hr15 or 1hr30. Using water? Like 4 or 5 hours probably.

    Give it a try, inquiring minds want to know, maybe it will work.

    No It is a sole purpose unit. And i don't really have any room in this utility room to install any more equipment.

    But is all goes well in a few years I would consider building a new shop to house my stills.

  • @Unsensibel said: I would start working backwards.

    What's the kettle size you're looking for?

    How much of a heat mantle does that size have?

    What's the delta T you need to maintain for a run to have enough evaporation?

    Overall, it seems like an inefficient way to heat as you would only benefit during the heat up of your mantle. Once the delta between your mantle and boiler medium is small, the benefit is marginal. Additional, if you push your water/glycol temp past 102C your boiler is starting to cool your mantle unless you isolate the us.

    Agreed. I would plan on isolating the closed loop system from the kettles heating jacket once I have maxed out temp and have to turn on the direct immersion units.

  • edited July 2016

    @grim said: Using the boiler and a heat exchanger to bring oil to temp, before transitioning to elements is an interesting idea.

    But installing a boiler is usually as expensive as a boiler itself. Installing that boiler in a commercial setting might cost 5 grand. What's the ROI on that compared to just going steam?

    image

    Luckily I already have this guy installed for other purposes. So I may just be the guy to give this a go. Worst case at least I will be able to run the bain-marie via direct immersion elements.......

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  • edited July 2016

    Nice setup, but why the two indirect storage tanks and a separate hot water heater? I see you have the plate heat exchanger installed already.

  • So Just to explain a little what is going on here. The two tanks to the right of the Boiler are the heat transfer media aka "food grade treated water" each tank is 220 US Gallons, so essentially 1600 Liters in total.

    When I fire the boiler from room temp I can bring the operating temp up to 90 C in about 70 min. From there I distribute the heat transfer media to several other tanks and heat exchanges within my facility. And the boiler only fires maybe once an hour for a couple minutes to maintain the 90 C set point.

    So it really wouldn't be to hard for me to plumb this into my baine marie kettle. Weather or not it is separated by a heat exchanger.

    My goal is to preheat my kettles heat jacket fluid to as close to 100 C as possible at which point I would isolate the kettle from the closed loop system and take control with the direct immersion system.

    Even if this closed loop boiler system could run the kettle all by itself I probably wouldn't as the temperature set point is a 10C differential and would make running the still extremely painful.

    Hell I may even run both heating systems to turbo my warm up time lol.

    Another idea I had was to simultaneously circulate the wash through a heat exchanger to help get everything up to temp as quickly as possible.

  • edited July 2016

    Can Maintain Temp Between 240 F (115.5C) and 220F (104.4C)

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  • edited July 2016

    If I might make a recommendation, you might want to run the boiler for longer than it takes to simply raise the jacket to near 100c, because you'll be able to do that relatively quickly, I would guess in a matter of minutes. You'll want to keep that jacket fluid circulating at a relatively high gpm, maintaining a near-100c temperature in the jacket, for as long as it takes to get the wash temperature to the point at which you transition over to elements.

    Whether you can run both at the same time is going to depend on how much energy you are able to transfer into the wash. If you are limited by the surface area, etc - you might find you actually can't run both at the same time - if the jacket temperature is higher than the boiler water temperature, you'll lose heat in the other direction (if you decided to use something like a heat transfer oil in the still, separated by a heat exchanger).

    Do you have a still yet? Interested to know when you can try this.

  • Agreed. We just have our recipe still right now. Tried to call Larry at Still Dragon US yesterday. Finishing touches are going on our licenseing. I am guessing 6 months being a custom Kettle and all.

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