Hi All,
First off a disclaimer - I'm totally new to distilling and don't even have a still yet - I'm still trying to wrap my head around basic concepts, so go easy on me if this is a dumb question! Really quick question : Does the surface area of the boiler effect the choice of column diameter? I'm assuming that the smaller the surface area in the boiler letting off the vapors, the smaller diameter of column I want to use. Would that be a correct assumption? I want to make a very very small still, with a boiler surface area of roughly 6 inches.
You have to worry more about the column dia in relation to amount of vapor, not boiler surface.
Surface area at the top of the boiler, in itself will have no impact on the amount of vapor coming off the pot. There have been experiments that show this. The amount of vapor coming off the boiler is due to energy and efficiency (btu's, how energy is applied to the boiler and insulation).
Very large still boilers that have columns off the still, use proportionally small pipes to transfer the vapor to the column.
Even a 200-300 gallon still will use only a 3"-4" transfer pipe to move the vapor. Now, using a small tube to transfer the vapor will cause other problems. Vapor speed could be very high when the vapor reached the column. So the column dia has to be right.
So in the realm of a boiler with a small top...you still have to factor the amount of vapor, vapor speed and the type of packing in the column. Even if the column can handle the vapor speed and get the ABV you're after, then the Product Condenser most be sized for it also.
It's a balancing act between boiler size, energy input, column specs (dia, packing, height) and condenser. You can usually turn the heat down to suit the column, but never have too small a condenser.
It's great to have a group of people who are willing to share their knowledge so freely! Thanks all!
To recap the comments so far, let me see if I have this right.
Dad300: Assume I have a boiler that is a 6" diamter tube stainless steel tube, 24" long, so that it can hold one gallon of mash; as long as it's properly insulated and heated, it will put out the same amount of vapor as a boiler with, say, a two foot surface area? That seems absolutely incredible to me! Great! Is there a calculator out there that can help me determine the diameter of the column in relation to vapor speed and all other variables that would influence my decison? From what I can see, it seems like the general "go to" diameter is 2"...
Rockchucker: Do you have any links you can direct me to regarding the question of quality of product and boiler surface area? It'd be nice to get as much information on this as I can.
NZchris: Hmmm, being a beginnner at this, I just assumed that most of the particulates would be trapped in the mash, as the vapor is basically "clean" already. Am I wrong in this thinking? What particulates are you referring to?
Dad300: Assume I have a boiler that is a 6" diamter tube stainless steel tube, 24" long, so that it can hold one gallon of mash; as long as it's properly insulated and heated, it will put out the same amount of vapor as a boiler with, say, a two foot surface area?
A cylinder 6" DIA x 24" H will hold 2.9 gallons, so it would be fitting for a 2 gallon charge.Yes if the same amount of energy were applied it would. In fact because heat rises...the tall boiler may be easier to heat.
Is there a calculator out there that can help me determine the diameter of the column in relation to vapor speed and all other variables that would influence my decison?
PaulL wrote:Hmmm, being a beginnner at this, I just assumed that most of the particulates would be trapped in the mash, as the vapor is basically "clean" already. Am I wrong in this thinking? What particulates are you referring to?
When a bubble bursts, it doesn't all fall back into the charge immediately . A percentage of it will be carried up with the vapor until it either leaves through the column, or drops back down. How much get carried over depends on viscosity, surface tension, the intensity of the boil, height and vapor speed. All else being equal, the smaller the surface area of the boiler, the higher the intensity of the boil and the higher the velocity of the vapor, so for fast stripping a large surface area to volume ratio is an advantage.
I forgot to say that an over-sized column can be even more detrimental to a still's design compared to an undersized one. To further push my point, research on the parent site calcs will guide you to the perfect reflux still design for your needs. After that all you have to choose is the type of column. (VM, LM, CM, CCVM)...
The most important aspect of right-sizing column and boiler is that your boiler has to hold enough alcohol for keep the reflux column in equilibrium throughout the entirety of the run... Too small of a boiler won't even provide enough alcohol for the column to equalize at azeotrope... At the hobby scale there's really no such thing as too big of a boiler (25 gallons, maximum) in comparison to packed column size... And on and on...
This is all part of the theories and fundamentals that you need to have a grasp of before proceeding... We're all just beating our gums together here, figuratively speaking, and tossing out information that is probably over your head right now... That's why I stopped in the first paragraph... We could keep giving you crumbs and further confusing you or you can do the research and have a firm grasp of the entire overall process... The information is here and you just need to read through it until it all gels in the gray matter...
Short answer: It all depends on how much alcohol is present in the boiler...
Really quick question : Does the surface area of the boiler effect the choice of column diameter? I'm assuming that the smaller the surface area in the boiler letting off the vapors, the smaller diameter of column I want to use. Would that be a correct assumption? I want to make a very very small still, with a boiler surface area of roughly 6 inches.
