Cheap fractionating still

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Seb
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Posts: 46
Joined: Wed Nov 21, 2007 12:04 pm

Re: Cheap fractionating still

Post by Seb »

Yummyrum wrote: Same thing when the fire dies down , less vapour ...the split is still the same ...the reflux ratio is still the same .....the purity is still the same .
The only thing that changes is the output rate .....but at least it is at a constant purity or ABV .

And I know this from personal experience here as our electricity goes up and down like a Yo-Yo . I built a LM/VM head and I never use it in LM anymore as VM is much more stable with a varying power source ......like a wood fired boiler :thumbup:
Thanks a lot Yummyrum. I get the difference now. Is the difference between both very significant? I mean I would totally go for VM to achieve vodka if only a wood fired boiler is available. But on the other side VM is a more complicated design, it requires 2 condensers and as my fuel can rate anywhere between 85 to 96 ABV, you can actually yield between both, it's a bit up to you, your car engine won't complain... in that case I wonder if such an improvement in the regularity of the ABV throughout the distillation process is worth it. Tell me, is that improvement that noticeable? and Is LM that irregular? Since you experienced both.
Seb
Novice
Posts: 46
Joined: Wed Nov 21, 2007 12:04 pm

Re: Cheap fractionating still

Post by Seb »

Yummyrum wrote:
Seb wrote: VM for a more constant ABV than with a LM? It's not obvious to me, can you tell me why?
OK I'll try .
1) You have a reflux still . It works by needing reflux falling back through the packing to increase the purity .
The purity that you get is determined by the ratio of how much you take off verses how much return down the packing ......its called the the reflux ratio .CM , VM , LM ....its all the same at this point .

2) A LM ( Liquid Management ) still controls ( Manages) Reflux by adjusting how much condensed liquid you take off , this is usually set by a needle valve , the rest is returned as reflux .
OK that makes sense so whats the issue .
Stick some more wood on the fire , the boiler starts to makes more vapour , You are still taking off the same amount of product but suddenly there is heaps more overflowing as reflux .....and the purity goes up .

Guess what happens when the fire dies down .....less vapour ,........ you are still taking off the same amount set by the needle valve , but there is less reflux and the purity takes a dive .

3) So why is VM better ? in a Vapour management still , the reflux ratio is set by how open the valve is . This sets the reflux ratio ..... or the proportion of vapour that is taken off as product verses how much is condensed and returned as reflux . If the valve lets 10% of the vapour exit as product then the other 90% is reflux .

So how is it better than LM ?
Well if you stick some more wood on the fire , you get more vapour . 10% is still going to exit as product and 90% is still going to be refluxed so the reflux ratio hasn't changed ......therefore the purity hasn''t changed either .

Same thing when the fire dies down , less vapour ...the split is still the same ...the reflux ratio is still the same .....the purity is still the same .
The only thing that changes is the output rate .....but at least it is at a constant purity or ABV .

And I know this from personal experience here as our electricity goes up and down like a Yo-Yo . I built a LM/VM head and I never use it in LM anymore as VM is much more stable with a varying power source ......like a wood fired boiler :thumbup:

So I can see why folk are suggesting Bokas as they are under normal stable powering conditions a good still but in your circumstances I think VM is the go :eugeek:
After some reading I will definitely go for a VM in this case. I just wanted to come back and say thank you.
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