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Stills and higher %s

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  • DAVID REID
    Rob, Tony,Dean, et al, I would not distill without packing as what makes it to the top of the column although high in ethanol carries with it other alcohols
    Message 1 of 1 , Apr 4, 2000
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      Rob, Tony,Dean, et al,
              I would not distill without packing as what makes it to the top of the column although high in ethanol  carries with it other alcohols and other contaminates which you are trying to separate out and eliminate by true reflux and cooling on either side of the ethanol takeoff (a bit akin to getting rat or mice droppings, or chaff and other rubbish with barley, wheat , maize or whatever you are intending to ferment into alcohol). In other words what I am saying is that your packing acts as a screen separating the wheat from the chaff etc, or the many thousands of mini-distillations which slowly separate the pure ethanol from the wash and slowly allow you to distil pure drinking alcohol. Just as you wouldnt use a gravel sieve to screen out sand the better the packing the better the separation.  I personally occassionally use my small glass still from which I get 93% alcohol without packing when I am in a hurry but only use the middle cut and recycle the rest. (Not good practise and something I am trying as quick as I can to get away from). I have done this more to understand the true capability of my more limited equipment. As Mike Nixon would point out without packing is a bit like giving the molecules a good kick up the backside and along with these you are likely to shift quite a lot of unwanted molecules. Tight Temperature control is therefore very important
      The fusel smell is almost definitely the result of insufficient distillation ie: insufficient reflux and separation. Having the temperature too high causes the same problems. In other words you are carrying some of the unwanted alcohols and contaminants with the vapour  and condensing this out with the ethanol distillate. If you have a sensitive nose try smelling the distilled alcohol and you will get a very faint yeast type smell.
      Rob if I was you I would try using the ss scrubbing pads that Mike Nixon and John Stone so much advocate as they are the best alternative available to you at present and are a very cheap solution. Make sure you get good ones though. The 3M brand appear good. Yes there are better packings available but as previously mentioned they cost. Some of them can cost more than the cost of the still alone. I am still waiting on the manufacturer concerned  to make mine and do not want to complicate the situation further by providing a lot of details. Like any very good business the company concerned has more business than it can handle and they prefer to concentrate on their big orders where they can make a lot of money and I have to wait my turn. I will keep this group informed as things develop. Suffice to say that the difference between these packings and pot scrubbers is that these packings are a structured packing whereas scrubbers are not. Improperly used scrubbers can compact and very quickly foul up. They therefore need regular backflushing and maintenance.
      What is important with the packing chosen is the interfacial area ie: Contact Surface (m2 to volume) and voidage or free volume (% of open area). Cant quite remember the exact figures but offhand raschig rings are approx 50% more efficient than solid packings like marbles, pall rings are 30 to 40% or even more efficient than raschig rings, and other specialized packings can be up to 70% more efficient again. Pall rings by the way are generally used in a lot bigger columns and their main use is for fractionation (mostly used for chemical separations). One or two of the specialized packings have very high m2/m3 and high open area so their efficiency is a dramatic improvement over the traditional packings. Most of the developments have come about in the last 100 years with pall rings being developed around 1930, coming into use around the second world war, and a lot of the impovements only happening from the late 60s and 1970 on.
      Todate I have largely refrained from speaking out too much apart from the odd cryptic and caustic comment about a lot of the stills available in NZ and overseas for home distillation as I do not want to ruffle too many feathers  or cause a lot of arguement. I also admire and repect a lot of the work done by  people such as Peter Wheeler and Malcolm Willmott of Spirits Unlimited, and others who did a lot of the early pioneer spadework getting the industry legalized in NZ and are the reason why we have got to where we have got todate. While I have advanced fairly rapidly in regards to still building a lot of these people and others on this list can and could teach me a lot in relation to making spirits.
      Despite this the truth of the matter is that a lot of the stills available are not up to scratch and in terms of performance could be improved significantly. In terms of advancement and comparison in many ways we are still back at the Model T stage with most of us who are a bit more advanced not making it to the Model A yet. A great advantage over the horse but still a long way to go.
      All in the meantime as I must get on with other things.
      B.r.,  David  Reid   
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