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Surface area for heating pipes?


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I need help on calculating the surface area required for copper internal heating pipes in a 3000ltr / 800 gallon wash still design I'm working on. The pot size will be <>2000mm/1200mm - 79"/47".

I'm thinking circulating thermal oil instead of steam as the easiest option for heating the still.

My understanding is thermal oil runs at about 300C / 572F, with the oil being pumped through an open system (zero pressure) via a header tank. The heating side will be gas fired.

Agitation will be part of the design equation, any thoughts welcome.

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Instead of using a kettle with heating pipes inside, have you considered just starting with a jacketed tank instead?

Perhaps something like this: http://www.sigmapackaging.com/equipment/detail/8443

And because I always hate when people respond to my posts without actually answering my question; I have spent 20 minutes trying to teach myself how to answer your question. Best to assume everything below this point is wrong..

800 gallons = 6,400lb of water

Lets assume you need to heat from 70F to 212F for an increase of 142F

142 degree temp gain * 6,400lb of water/mash is 16,131,200 BTU

We want to get to boiling within an hour, so we need about 266,666 BTU per minute or 4,700,000 watts

The heat transfer coefficient of copper for water is about 400 (W/m2 K)'

Im going to assume a heat fluid temp of 400F

Using an online calculator it looks like it might take about 80 Square Meters of copper surface area to get 4.7 million watts transfer

Thats almost 900 Square Feet. Sounds like a lot..

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Thanks a lot for your efforts HedgeBird.

One upside, the wash boil temp will not need to go over about 97C, so that will reduce the required temperature increase required down to 60C or 106F, dropping the heat up time down to 45 minutes before we take into account the lack of surface area.

Looking at the jacketed option the available pot surface area is 9.34 square meters or 100.5 square feet (sides and bottom) the heat up time is going to blow out to some what. 5 square meters of area could be achieved with 75 meters or 15 revolutions of 50mm/2 inch copper pipe around the inside of the pot

Thats for the link, I have look at steam kettles for conversion to still pots. The plan is to head down the all copper route.

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I did not sleep in a Holiday Inn Express last night.

If the overall system was able to achieve a 75% efficiency rate, which would be very impressive, you'd be looking at 1.2 million BTU gas burner to get you a 45 minute heat up, so figure a margin of safety of 20%, 1.5 million btu?

To hell with the coil, I want to hear about your hot oil heater.

Commercial hot oil (HX Fluid) heaters are significantly more expensive than more common steam boilers. Keep in mind that at the temps you mention above, your HX may be flammable if exposed to an ignition source.

To pump the fluid through the roughly 200 feet of 2" piping (160 feet in the HX, and to and from the heater), you'll be generating some serious pressure on the output of the pump, as well as having to maintain some serious flow rates.

God help anyone that might be standing near a copper pipe if it were to burst due to damage sustained from the kinds of thermal stresses we're talking about here. Being doused with 400-500F degree oil would be a fate far, far worse than death. Don't get me wrong, I'm not saying steam isn't without risk at the scale we're talking about, but the engineering of process steam is readily understood all around the world.

New South Wales? Why don't you talk to the guys over at Stilldragon Australia. I just took delivery of a 1000 liter steam jacket boiler that's absolutely beautiful, 12" bolt flange at the top to mount whatever you'd like, insulated jacket for higher efficiency, even an explosion proof agitator. I hear they are now offering jacketed still boilers near 4000 liters total capacity, and the price is going to be very very hard to beat. I could see you spending more money on your proposed setup, or even a used Lee kettle than one of these, which would be nearly ready to run.

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The most efficient way to cook mash is steam injection. For some reason the large distillers and even moonshiners used live steam to mash and distill, but it has not caught on in micro distilling. Think about it, no jacket needed unless you want to cool with a jacket. Most cookers made for live steam have a cooling coil inside or the mash is cooled with a tube in tube or shell cooler. In a pinch you could convert a tank easy. Just have a check valve between the boiler and the cooker.

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What do you recommend for steam filtration and separation when talking direct contact? I'd always thought that the price tag on culinary steam filters and separators (any any associated steam trim) was very expensive to buy, as well as to maintain - since the filters are considered a consumable. Also, if any additive ever touched your boiler or piping, is the approach is even possible?

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