Temperature Gradient in boiler ??

In our view 30 gallons and under is considered hobby size. Do not bring anything larger than this to our site.

Moderator: Site Moderator

Post Reply
MrBee
Novice
Posts: 45
Joined: Wed Mar 02, 2016 4:26 pm
Location: Not close enough to Blue water

Temperature Gradient in boiler ??

Post by MrBee »

Good evening all ,
I m used to using a copper pot still with a hot plate under it so never had this issue before.

I built a new boiler using a 1/2 barrel keg, pretty typical build with the heating element in the side as close to the bottom as possible, 4500 Watt.
Today I tested the electric controller by putting 10 gallons in boiler.
Everything worked as planed. I was just heating this with the 4" top covered by a piece of wood just to keep the steam in.
I dropped a temp probe down in to monitor the temperatures I wanted to see the difference at several levels of the water depth.
What I found was the water at and above the element heated as expected however, the water below the Element stayed at 65*f even as the temp above the element rose to 135 then 165 f. I could not touch the boiler in the area of the level of the element but the underside of boiler was still cold. The temperature of the bottom 2 - 3 gallons never went above 70 f till the water really started to churn at around 200f.

I did try a few searches however all that I can find info on is temp of columns and related stuff.
It seems to me that the heads, hearts, and into the tails will be coming over before the bottom 2 gallons even starts to release its alcohol.

So will this change when the content is 9% alcohol ?
Is there something some of you are doing to mix the charge as it heats ?
Is there something I have missed in my reading ?

Thanks

MrBee
User avatar
shadylane
Master of Distillation
Posts: 10363
Joined: Sat Oct 27, 2007 11:54 pm
Location: Hiding In the Boiler room of the Insane asylum

Re: Temperature Gradient in boiler ??

Post by shadylane »

As you noticed, There's a big temp gradient in the boiler.
Once part of it begins to boil. it will stir itself up
User avatar
skow69
Site Donor
Site Donor
Posts: 3230
Joined: Tue Dec 06, 2011 3:03 am
Location: Cascadia

Re: Temperature Gradient in boiler ??

Post by skow69 »

MrBee wrote: It seems to me that the heads, hearts, and into the tails will be coming over before the bottom 2 gallons even starts to release its alcohol.
The heads, hearts, and tails won't come over until it boils.
Distilling at 110f and 75 torr.
I'm not an absinthe snob, I'm The Absinthe Nazi. "NO ABSINTHE FOR YOU!"
User avatar
Badmotivator
Angel's Share
Angel's Share
Posts: 937
Joined: Tue Jan 20, 2015 9:01 pm
Location: Oregon

Re: Temperature Gradient in boiler ??

Post by Badmotivator »

I have windows into my keg, so I can see how the liquid behaves. You have nothing to worry about. Once it is boiling the movement of the charge is very very vigorous.
MrBee
Novice
Posts: 45
Joined: Wed Mar 02, 2016 4:26 pm
Location: Not close enough to Blue water

Re: Temperature Gradient in boiler ??

Post by MrBee »

I realize that once it starts to boil that all the liquid will churn and combine .
Based on what temperature the lower alcohols boil it would seem to me that some of the fores and heads would start to come over at 135 - 170f and at that temp the water in the bottom 3 - 4 gallons was still at 70 F so the fores and heads would still be in suspension there.
Then all at one time a boil happens and all of the sudden that 4 gallons releases those alcohols and would come over with the late heads and possible early hearts.

I'm sure it dont matter if your running a column however, if I'm just running a pot still i'm not waiting for any equalization.

Maybe I'm over thinking this but I know from running my copper pot with it sitting on a stove burner that when the liquid temp reaches around 168F I see vapor coming into the condenser .
If running my thumper I guess it wouldn't matter because by the time the thumper is about to send vapor to the condenser the main boiler would have already been to a rolling boil and combined all it's contents.

I should be up and running at least the sacrificial bier in the next few days so will be able to see how things come out.

MrBee
Post Reply