boka condenser size

[pjeterschornstein]

Hey all!

I'm planing to build my first reflex- a boka still.
I would like to use it with a circulating water system .I'm a bit confused about the best design for it to not build back pressure and that would fit into a column.
I was thinking to try to wind a 8mm dubble helix and to make it about 15cm. would something like that would fit into a 2" column?
would you recommend using a cold finger or other suggestion?

[Expat]

Before answering your question need to know how much power you're pushing. 5500watts? Less.... More? Gas or electric. Makes a difference to the required condenser size.

Generally a well built 6" double helix will do the job for most setups in the 2" range.

[cede]

Apart from the power you would like to kill, if you will be using a pump to recirculate, cold finger might help as it will split the flow between the two coils and make less back pressure.

[pjeterschornstein]

Can you tell me how it'll make a difference Expat ?
Because that's a whole other consideration I'm thinking about; right now I would use it on an electric stove for a while. Later, I'll be working on a farm and running on solar power so either stay with a stove or put an element (haven't researched about elements much but read here it's more efficient and consume less). I'll also have biogas there but I don't know if it'll give me enough cooking hours and I'm a bit nervous about adding open flame to the mix.
Was planing on making at least 8" long condenser.
Cede, Cold finger looks more complicated to build for my level+ I read people say that if I use 8mm coil instead of 6mm I wont have a problem and that double helix is more efficient. I also cannot find any comprehendible guid for building and explaining those but maybe I haven't searched enough because I didn't think I'll go this direction.

[still_stirrin]

Can you tell me how it'll make a difference?....I would use it on an electric stove for a while. Later, I'll be working on a farm and running on solar power so either stay with a stove or put an element (haven't researched about elements much but read here it's more efficient and consume less). I'll also have biogas there but I don't know if it'll give me enough cooking hours and I'm a bit nervous about adding open flame to the mix.

Was planing on making at least 8" long condenser...if I use 8mm coil instead of 6mm I wont have a problem and that double helix is more efficient...

Well, the “type” of heat input doesn’t really make much difference. However, the “amount” of heat input does. And the “type” of heat input affects the “contol” you have over regulating it. Propane is good for “magnitude”, but sometimes hard to properly regulate. Electric power is much easier to regulate, but has a greater “first cost”, meaning it is more expensive to build the equipment. But it does give you better control over how much heat you apply and the steadiness with which it runs (this will affect the quality of the reflux and ultimately the purity of the product).

Here’s a thought: while the double helix gives good surface area exposure to facilitate the condensation, they can be very tricky to fabricate. Using 8mm tubing is good but in order to fit a coil into a 2” pipe, the ID of the helix will be very tight and the copper will have a tendancy to kink when wrapping.

The smaller diameter (6mm) would be easier to form but the internal water flow loss will be significantly greater. So your pump would have to work harder to push a flow through it.

If you can find 3/8” corrugated stainless steel tubing, it is quite easy to twist into a coil that will fit inside the 2” pipe. And a single coil has very good surface area in contact with the vapors. You probably won’t need a cold finger if using CSST.

But back to coil length...an 8” coil section should be adequate for up to 3kW of power. And I would doubt your hotplate will put out more than 1.5kW. And for a Bokakob, 1.5kW will work on a 2” column acceptably. A little more power would be nice, but you really don’t need more than 2.0-2.2kW for that size Boka.

I have a concentric designed LM reflux head. And it uses a double wall reflux condenser section (1-1/2” inside of a 2” pipe). I stuff a copper scrubby in the top of it and it works quite well. My 1m x 2” column sits on top of a keg with two 240VAC 4.5kW elements running on 120VAC giving me roughly 2.2kW total power input. The LM can run 96.3% azeo handily from a 30%ABV low wines charge.

So, good luck with the tubing bending...it can be tricky.
ss

[still_stirrin]

Oh, and here’s “the elephant in the room”...electric kitchen stoves have thermostatic controls on the heating elements. So, they cycle on & off while heating. Plus, most hotplates likewise have thermostats on the heat setting controls. If you plan that solution, you need to modify the control circuitry to disable the thermostat (the boiler requires a steady heat input for steady vapor production).

Look into the Related Electrical Accessories forum for more information about this type of corrective modification.
ss

[Expat]

+1 to what SS said. When I asked what type of heat you were using its important because different sources vary in efficiency of heating wash. Electric stoves won't work.

[pjeterschornstein]

OK. Looks like I need to read much more before I start with this.
I can get 3/8” CSST. doesn’t look much more expansive. I’ll get it if you say I won’t have trouble with the pipe. how long of a pipe do I need for 8”?
Also definitely got convinced about the element. I’ll start reading about it but can you tell me how much such thing cost? seen between 5-250 dollar so I’m a bit confused..I have a 37liter pot I probably install it on.
I’m still really trying to figure out the size of still I want.. I don’t want to go extreme for first one but I want it to be efficient because I want to use this one partly for fuel.
are there downsize for going for a wider column accept for the initial cost? thinking about going to the scrap yard and see what I find for a copper column and go from there..
Sorry for the novice dilemmas… still getting initial miles on my pot still