bought a keg -want it as a thumper -will my still drive it ?

[Pikey]

I just bought a full size keg thats 11 gallon imperial and quite a big lump of stainess.

First thoughts are to just poke a single hole thumper connection in there and double my capacity from 25 litres (Now) to 50 litres with thumper half full of wash. However the still is 2.5 kw and I' wondering whether that will be enough to drive both ? (Especially considering the amount of stainless to be heated to no real purpose. )

I really don't want to put a separate heater under the keg since I run indoors and also propane is expensive (plus I don't have a ring ). But I really don't want to boil the still dry either, although the elements are "Underfloor" and I don't think I bypassed the safety cutout for boil dry.

Can any of you with thumpers tell me how much still charge I am likely to lose in a full distillation with 5 gallons in each please ? (Talk to me in gallons, litres or US gallons - whichever is easiest for you.)

Time wise it will take as long as it takes - although I may add insulation if we think that will help ? Normally I reckon around an hour to heat up to produce or a little either way depending on outside temperatures, so I'm expecting perhaps 2 hours for the two combined ?

I'm really getting quite keen on this !

[Shine0n]

Pikey, wish I could help with the question. Expecially on the electric side of things but I run propane but I can say a few things regarding heat up an fill up of the thumper.

I run outdoor in an uncontrolled environment, temperature can play an important roll in how much the thumper will fill during heat up. In the winter I've started with 10 us gal in the thumper and ended up almost completely full when the run was over, no insulation on boiler or thumper.
I will if still in the same situation this winter insulate the thumper.
If your keg is 11 imperial it should mean it's 15.5 us? Either way if you fill your boiler to the max and run as hard as you can you might be able to run it expecially if you insulate. Try with 5 gallons in each and see the volume of each when finished, if the boiler is way low you know you may need to up to 5k if available to you or you can preheat the thumper somehow it would shorten heatup time.

[Truckinbutch]

I run 15.5/15,5 in pot still mode with a Liebig condenser . Strip runs are 12.5 US gallons of clear mash in the boiler and up to 12.5 US gallons of cloudy mash in the thumper for strip runs . Run it hard and dirty . Pull a quart of fore shots/early heads and dump the rest into a carboy for a spirit run . Yield is about 3 1/2 -4 US gallons of low wines .
Never have overrun the capacity of the thumper on strip runs .
60k btu Bayou Classic propane burner gets my first drips in about 1hr 47 minutes .
Spirit runs are diluted to >40% abv and I usually put about 3 US gallons of liquid in the thumper for the spirit run . I've never accumulated more than 5 US quarts of extra liquid in the thumper during a spirit run .
Your run times may vary with electric but the physics remain the same . Heat in/product out .
Hope that helped .

[The Baker]

I've got this radical idea for pre-heating (boiler/ thumper). In cold weather.

Take one or more containers of wash into the nice warm house maybe a day before distillation.

Cover with a pretty flowered cloth to keep Mrs. Baker (more or less) happy.

Geoff

[Pikey]

Thanks lads !

Shine0n - 1 Imperial pint = 20 fl oz. I believe yours are more logical at 16 fl oz so 1 of our gallons = 1.25 of yours - 11 of ours = 13.8 of yours.

Sadly I don't have hard wiring out there so 10 amps at 240 is about as much as I want to push electric wise. - I do have a keg with electric heating, but I believe it wants about 4kW so I need a Sparky mate to connect a 16 AMP or HArdwire me a cooker socket out there - MAybe I can do a little measuring and use a power controller - we'll see.

Yes I think insulation of the transfer pipe (Lyne arm ?) and the thumper are quite relevant too.

Thank you too TB for reminding me it's the physics that matters.

When I think about it in "wavy hand terms", it takes me around an hour to heat the still up to boiling. so if I push the same amount of heat over, it should take about another hour for the thumper to get there. However the still will produce around 1 gall of likker in that hour and the likker condensing in the thumper will raise the abv of the wash to maybe 20 - 23 % ? and the abv of the still output will have dropped. This means the temp of the vapour coming over is hotter than that exitting the thumper by quite a lot. Therefore MOre vapour will now leave the thumper than is entering.

If I remember correctly Kareltje did some work on this aspect and produced some nice spreadsheets.

That should continue right to the output abv nearing zero because for the last part of the run, I'll be pushing over pure steam.

Not sure where that leaves me with 5 gallons (Imp) in each, but I don't think I'll have much still charge left by the time I've pushed 3 gallons or so out of the thumper. I'm thinking it should be ok ! (But maybe not by much ! )

Thanks for your comments Geoff - If I'm fermenting indoors, I have to supply extra heat in winter, so that wouldn't work very well for me !

[The Baker]

Pikey said, 'Thanks for your comments Geoff - If I'm fermenting indoors, I have to supply extra heat in winter, so that wouldn't work very well for me ! '

Yeah, I ferment in the shed with fermenters tucked up in blankets, insulated underneath and aquarium heaters.

Geoff

[Kareltje]

Yes, you are right: I did some work on thumpers.
As my stills are metal I can not see what happens inside, so I tried to make a model. I of course tested it as good as I could, and it more or less shows what happens.
In this case I took 2 vessels of 10 L and filled them with 5 L of 10 %ABV each. More or less the same as Truckinbutch described.
When starting with a cold thumper (20 dgrC), we get this:

When we preheat the thumper (60 dgC) (as I always do), we get this:

N.B.: The line for temperature is just to indicate the thumper thumps, not to shows the real temperature.

The difference is mainly at the start: it takes some time and some volume to heat the thumper from 20 to 80 dgC. This can be done because the heat of condensing is much greater than the specific heat of water/alcohol. We also see that the starting % in the thumper is higher when starting cold, because the extra needed vapour also brings extra alcohol.

You also see how the transfer of vapour from the boiler is rather constant (assuming constant heat-input!), so after a few runs you can estimate the remaining volume in the boiler. And it is clear, that halfway the alcohol is completely transfered from boiler to thumper, so talking about energy it is better to stop the boiler and start firing the thumper. That is why I put both side by side on my stove and why I inserted a valve between boiler and thumper (with a thermometer). DO NOT forget to disconnect the boiler when you close the valve! The valve is just to close the thumper!
But when you use the thumper to distill the slop of the bottom or when you can not heat the thumper, this is not an option.

(By the way: I will happy to send you the latest version of the model, but I am not sure I still have your mailadress.)

[Kareltje]

Oh, sorry, I forgot to answer your question: I run boiler and thumper both half filled with 600 W. But I admit: I insulated both with a large oilbarrel over them. Saves me about half the energy.
So I think your still can drive your thumper.

[The Baker]

Oh, sorry, I forgot to answer your question: I run boiler and thumper both half filled with 600 W. But I admit: I insulated both with a large oilbarrel over them. Saves me about half the energy.
So I think your still can drive your thumper.

So we would probably call it a shield (against wind, and cold air) rather than insulation....

Enjoy your posts.

Geoff

[Pikey]

Oh, sorry, I forgot to answer your question: I run boiler and thumper both half filled with 600 W. But I admit: I insulated both with a large oilbarrel over them. Saves me about half the energy.
So I think your still can drive your thumper.

Thanks for both your posts @Kareltje - much appreciated