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Hello,

After finishing my first still (Nixon-Stone) I've developed an addiction to the building process.

Already I am keen on building another.

So I thought, why not make something a bit more exciting? I then sat down and drew up a design for a continuous still very heavily inspired by the Coffey Patent still.

The only major difference is that I wish to do this with packing and only one plate, the plate being only used for the collection of what will hopefully be near-azeotrope ethanol.

Can anyone see any major problem that could arise in this still design? I know that it will be difficult to control at least, but there are probably some design flaws I've overlooked. I also know it's a complicated and relatively expensive-to-build design - but I've run into some disposable income lately.

I can see a problem now. There's no real reflux condenser (the wash coil above the spirit plate is primarily for condensing the product to fill the plate). Options I could try are to add Bokabob style slanted plates and a needle valve, and only taking off a portion of it. Or I could add another reflux condenser below the spirit plate.

Or maybe in an extreme case the spirit collection could be shifted to a third column specifically designed for seperating hearts and heads.

I dunno, it's getting quite late in the night here in the UK and I'm not sure I'm thinking straight.

I suspect the wash-preheater coil isn't going to give you enough cooling power for near-azeotropic ethanol. You'd need greater than 90% reflux, I'd think, which means you'd need over ten times the cooling power as is required to condense at your take-off rate. And your cooling power is restricted to the temperature shift of your wash from ambient to its boiling point.

So, I suspect you might need a second condenser running cold water, above the wash preheater / condenser, to get that kind of reflux - otherwise, nearly all good stuff would come out the top along with the heads.

dragonfrog wrote:I suspect the wash-preheater coil isn't going to give you enough cooling power for near-azeotropic ethanol. You'd need greater than 90% reflux, I'd think, which means you'd need over ten times the cooling power as is required to condense at your take-off rate. And your cooling power is restricted to the temperature shift of your wash from ambient to its boiling point.

So, I suspect you might need a second condenser running cold water, above the wash preheater / condenser, to get that kind of reflux - otherwise, nearly all good stuff would come out the top along with the heads.

That can certainly be done. Note that I am not expecting perfect seperation of heads and the ethanol anyway. I'll settle for the heads takeoff being some heads in mostly ethanol, because I can save it and re-run it another time.

Your heads takeoff should be much higher, if useful at all. You may need a later batch distillation to remove heads. Also, maybe a flow regulator on the spent wash drain... I can see the pressure forcing everything out the bottom (make the bottoms reservoir deeper?)

canadianmoonshiner wrote:Your heads takeoff should be much higher, if useful at all. You may need a later batch distillation to remove heads. Also, maybe a flow regulator on the spent wash drain... I can see the pressure forcing everything out the bottom (make the bottoms reservoir deeper?)

You have definitely got a point there. I suppose I could use a valve there, or maybe alter the shape of the drainage pipe (to be similar to what's seen on column 2 for the feints return) to balance the pressure. Note that the drawings aren't really to scale, indeed the height between heads takeoff and spirits takeoff would probably be about the same as between the steam input and the spirits plate in the finished still.

Rather than design a continuous still from scratch, consider modifying your Nixon-Stone. Instead of water, pump wash through your condenser, then inject 1/3 to 1/2 up your column. Mount the column to a small pot (on a hot plate) with a drain. Done.

canadianmoonshiner wrote:Your heads takeoff should be much higher, if useful at all.

+1 if your heads are full of ethanol chances are your ethanol is full of heads.

manu de hanoi wrote:

canadianmoonshiner wrote:Your heads takeoff should be much higher, if useful at all.

+1 if your heads are full of ethanol chances are your ethanol is full of heads.

I am putting a greater distance between spirit plate and heads takeoff than in the diagram.

Production of this still has begun with the building of the spirit plate from a 3-inch copper disc, some 3/8" pipe, and a 22mm copper end-cap. (It's a bubble-cap design). The rectifier is a 3" column and most likely the same for the analyzer too (I haven't bought any parts for the analyzer yet).

I have also been thinking and found a dilemma in the analyzer design. The wash feed will simply channel straight through the packing to the bottom of the column! This should be a problem that can be dealt with, however - worst case scenario the analyzer column may become a partially-plated design.