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Showing content with the highest reputation on 05/03/2020 in all areas

  1. @Modernity I would be wary of using perforated trays if you are going to be distilling grain in. If you are going to make the trays into a removable cassette then that could work if you need to clean them. Maybe wait for @PeteB to post his photos and diagrams to see how he did it. He and I discussed using very simple splash trays before he built his first column, and he came up with a very innovative way of installing the trays but I have not seen what he finally built. If you do go with the perforated trays be generous with your downcomer sizing. I like to allow a downcomer residence time of 10 seconds, based on the full volume of the downcomer. If your tray spacing is around 300 mm then it would be better to install a 3” downcomer. I also prefer D shaped downcomers. You can make these easily by splitting a 6” pipe in half longitudinally and then welding in a plate to seal the straight part of the D. Half a 6” pipe has double the area of a 3” pipe, but is still only 3” wide. Some references for downcomer design also specify a maximum velocity, but this only comes into play with large hydrocarbon columns that can have +3 ft tray spacings. The hole area (perforations) is much harder to calculate. I found this reference that states % Hole Area: This is the ratio of hole area to bubbling area. The default practice is to target a hole area of 8 to 10 % of bubbling area for pressure services. The acceptable range for percentage hole area is 5 % to 15 %. However for some critical services, we can go % hole area up to 17-17.5 % provided that weeping is under control. Hole areas below 5 % are not used. Despite their claim that hole areas of less than 5 % are not used I designed a column that uses 2.9 % and has been running very stably 24/7 for 33 years. That column was a bit unusual in that it had a very high liquid to vapor ratio and I had a lot of pressure drop to play with. For your stripper you will also have a relatively high liquid to gas ratio and I would guess that it will need 6 to 8 % open area, but that really is just a guess. If the hole area is too small it will unnecessarily limit the capacity of the column, and if the hole area is too large the trays will weep and their separation power will be low. Rather than taking the risk of deciding on the hole area yourself it might be better to buy trays from a supplier with a track record and who offers a guarantee. (I am not touting for business – I do not supply equipment or consulting services.)
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  2. Try the cheap ones. The pleated filters will more likely require a higher pressure to push the liquid through. When I use absolute filters it takes 3-5 Bar of pressure, you can not achieve this with vacuum. I have to polish filter with a pump separately and then later run the bottle filler with a cheap depth filter.
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  3. So Im curious about the effectiveness/efficiency of the number of plates on a still. Now lets say I want to make vodka and I go with a larger still manufacturer, their set up will have 16+ plates. But if Im starting on a tighter budget and go with a component type set up, say the hillbilly flute or still dragon, I can apparently get by on making vodka with far fewer plates. Why is this? I get that more plates = a more pure distillate so it that it? The bigger systems simply produce a superior product in one run vs a smaller system requiring maybe two runs to get something comparable? Is it a scalability issue; bigger pot/more vapor = a need for more plates? Or, is it something else entirely and Im way off base/have a huge gap in my knowledge/understanding? EDIT: Just to clarify I am not sold on producing vodka. In fact I'd say I'm 95% set against it. This is just something that, as I've been researching and drafting my business plan, I've been really curious about.
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