I dont understand....

[Grayson_Stewart]

Brought over from old forum

p3t3th0m
(stranger)
05/18/04 06:48 AM

I dont understand....

Heating elements.

If alcohol boils off at 78 oC, why are so many still just heated using an element that gets hotter and hotter?

Is it just a case of turning on, and waiting until tails appear?

Or does the liquid take a while to heat and by the time the element heats up your finished anyway?

I mean, you dont take a pot stil, put it on your stove and then put on the highest setting do you? Or do you....?

Same with Fires, how can you regulate a fires temporature, and what temperature dos one want to get the wash/gas anyway? 78-to-100 degrees? Or get the mash boiling away, witht he idea that it must always go Heads, middle, tails - you just do it faster?

Ive read and read and read ont he web, but the heating temperature just doesnt make sense to me (people mentioning boiling their mash - but theres 80% water in it too so surely boiling point is 100 degrees?)

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tater
(enthusiast)
05/18/04 06:55 AM

Re: I dont understand.... new [re: p3t3th0m]

I use a high heat to bring still up to boiling temp fast then back down to maintain distilling temp.

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grayson_stewart
(stranger)
05/18/04 07:33 AM

Re: I dont understand.... new [re: p3t3th0m]

Multiple elements are used to bring the liquid up to boiling temperature fast. After the liquid reaches boiling temperature, most people turn off the larger elements and only use the smaller ones.

By using more elements, leaving the oven on high, etc. you are pumping greater energy into the liquid. Placing greater energy in the liquid will force a more vigorous boil and force vapor up the column faster...not always a good thing. You can get better product with a slower boil.

I use two elements to get up to boil quickly, then turn off the larger element and just go with the smaller for the rest of the run.

Good things may come to those who wait. But only the things left by those who hustle.

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Blanchy
(member)
05/18/04 07:59 AM

Re: I dont understand.... new [re: p3t3th0m]

A solution can only boil at one temperature at a given pressure (typically 1 atm. in our case). Pure water is 100 deg. C. Pure ethanol is 78 deg. C. A mixture will boil somewhere between those two points. Increasing the heat input just changes the rate at which the boiling occurs, while the temp stays the same.

The only heat source temperature that you are concerned with is the temperature of the metal in contact with your wash. Typically, this is the temperature that the wash is boiling at, especially if your heat input is low. If the temperature gets too high, then you can get localized superheat which leads to scorching.

Chuck