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TEORIE PE SCURT PT. UN CAZANEL MIC ...
http://homedistiller.org/legacy/refluxdesign.htm#hm
"AM CAZANUL MEU SI SUNT FERICIT ... "
Designing Your Own Still
So how do you put all this together to make your own still ? Say you're looking at wanting to make 90%+ purity, off a 20L wash.
Pot
To hold 20L you want at least another 1/4 spare for foam, etc. So go for something in the 25-30L range. I'd suggest something where you can easily lock the lid down, but also be able to get into it fully to clean it out. Suggestions include paint tins as seen in walt or AV25L or a preserving pan with a clipped lid like Teds at http://mwci.s5.com/.
These all have pretty thin lids, so to support the column, you may need a small flange to help hold it all up, or a stiffening plate/oversized washer to help strengthen the lid.
Heating Element
Probably in the 1000-1500 W size. Whats cost-effective for you ? A 1500W element will heat up the contents to begin in around 65 minutes, but a 1000W will take 98 minutes. If time is crucial, you could add a second element to act as a boost during the initial heat up.
Column Sizing
The diameter is based on the amount of heat you're using, whereas its length determines what purity you'll get. Its a hobby still, so I've assumed that the packing will be stainless steel or copper scourers - they only take about 1/2 the height that marbles do to get the same purity. You will also need to insulate the whole length of column too - plumbing suppliers sell slip-on piping insulation for around NZ$8/m
Diameter : 1 inch is too narrow for a 1380W element, but 1.5 inch is OK with a 1800W element. Roughly, lets say to use 1.5 inch for 1000W - 1500W and 1.75 - 2 inch for 1500W - 2000W. If in doubt, go up in size by say 0.25 inch. Too narrow will lead to all manner of problems & difficult operation, but too wide will only give a minimal reduction in purity. 2" is a well used, very reliable diameter that works under most circumstances.
Height : This is the purity. Use the wee interactive applet at the start of this page to see how the number of stages or HETP's improves the purity. Its easy to get the first gains up to 90%, but then more difficult to squeeze out the last improvements towards 95%+ Lets assume (we'll come back to this) that each HETP for scrubbing pads is around 15cm... then for a 15% wash, No packing, purity = 62% , 15cm packing = 82%, 30cm = 88%, 45cm = 90%, 60cm = 92%, 75cm = 92.8%, 90cm = 93.4%, 105cm = 93.9%. These won't be exact, and depend on a number of different factors, but it shouldn't be too far off. So, if height is a problem, and you're happy with low 90's, then 60cm should do ya. If you want to make a perfect vodka, go for 120 to 150cm. Normally I'd recommend at least 100cm, but the choice is yours, as it depends on the type of product you want to make.
These numbers assume that we've reached equilbrium nicely for each 15cm of packing. To do so, we need to provide heaps of surface area for the liquid and vapour to mingle over (done - using scrubbers), and that we're refluxing a large proportion of the vapour back down as liquid, rather than keeping it. But this means that our take-off will be rather slow. Eg we may be able to start out with a reflux ratio of say 3-4 (ie return 30-40mL for every 10 mL we keep) when the pot is very rich in alcohol, but later on, when its getting down in alcohol, we may need to increase this up to 5-10 to keep the high purity.
A reflux ratio of 4, with a 1500W element means that we're collecting at around 20 mL/min. Thus a 20L 15% wash will take a minimum of 2.5 hours to collect (20 mL/min), up to 5 hours at a reflux ratio of 8 (10 mL/min). The actual time will be somewhere between these, depending on what ratio you end up needing in order to deliver the purity you're after.
If the distilling time is taking too long, we can make the column taller, and then run at a slightly smaller reflux ratio, to get the same purity.
The collection rate is directly proportional to the element size, so if a 1500W element with reflux ratio of 4 takes 3 hours to distill, then 1000W will take 4.5 hours, or a 2000W 2.25 hours.
SA AVETI SPOR !
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"O să intru în păcat,/Sfinte Doamne, ţine-mă!
Pentru vin nu am ficat,/Pentru apă... inimă! "PĂSTOREL
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