just repacked a 2" boka now cant get above 92%

Reflux still design and discussion

just repacked a 2" boka now cant get above 92%

Postby Banksy111 » Mon Jan 09, 2017 1:02 pm

I have been using a 2" boka still packed with stainless pot scrubbers getting 94-95% consistently over a dozen runs, as I cant tell the quality of the scrubbers I replaced them with copper mesh. My last 2 runs I cant get above 92%. One run I think it was flooding because it was packed to tight, repacked it, seemed to run well but could not get over 92. The packed section is 1.5 m and is insulated.

Any help most appreciated
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Re: just repacked a 2" boka now cant get above 92%

Postby scythe » Mon Jan 09, 2017 4:23 pm

Pack it a bit more but not as much as it was when it was floodng.
How does the 92% taste compared to the 95.6%
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Re: just repacked a 2" boka now cant get above 92%

Postby coffe addict » Mon Jan 09, 2017 5:46 pm

With 1.5m of scrubbers it should easily hit azeo. I could with 1m of scrubbers and 300mm of copper off cuts.

Are the copper scrubbers a different thickness in the strands? If they are it could be changing the performance.
You could try 4/5 stainless and the rest copper which should be enough to strip the sulfides out...
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Re: just repacked a 2" boka now cant get above 92%

Postby Banksy111 » Tue Jan 10, 2017 9:34 am

The 92% is ok but i am trying to do a good vodka so i would like 94 or higher then i will water down to 40 and run again. The colum is packed fairly tight with copper mesh.the strands are all the same.would happily use stainless scrubbers again but having trouble finding any 304 all the scrubbers i can find here stick to a magent and the packet just says stainless, most likely a low grade.
Thanks for the reply
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Re: just repacked a 2" boka now cant get above 92%

Postby warramungas » Tue Jan 10, 2017 10:11 am

Not sure where you are but Bunnings near me have stainless scrubbers in their cleaning aisle. On one of the packets of 6 or 8 scrubbers it says 'Guaranteed never to rust'. About $7 a pack. I bought a few packs for my 3" build. I have a stack of copper already to help with sulphides but probably only half what I need to fill the column.
I'm not the greatest fan of stainless as when I last used them (real stainless) they seemed to imbue a 'metallic' taste into the neutral.
On a side note, if you're redistilling 40% through a 92% (on a wash) still and you're still only getting 92% I'd hazard a guess and say your scrubbers are too tight. Even if they were a little loose a 1.5 meter reflux column should shit in 95+% on a 40% run.
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Re: just repacked a 2" boka now cant get above 92%

Postby Doubleuj » Tue Jan 10, 2017 10:33 am

Could you have developed a leak? When cleaning/ unpacking her?
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Re: just repacked a 2" boka now cant get above 92%

Postby Banksy111 » Tue Jan 10, 2017 2:30 pm

Havent seen any leaks but will check again and will remove some packing to see if that helps
Thanks again
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Re: just repacked a 2" boka now cant get above 92%

Postby meerkat » Tue Jan 10, 2017 7:57 pm

The tightness of the packing will have opposite effects on capacity and strength. A loose packing will give you a higher throughput, but a lower strength product. On the other hand a tight pack will give you a low capacity (i.e. flooding at a lower throughput) but a higher product strength. If you felt that the tight pack was flooding then lower the throughput (less heat to still) and see if you get back to the 95% product. Finding the right compromise between capacity and strength will be a trial and error exercise.
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Re: just repacked a 2" boka now cant get above 92%

Postby Undertaker » Tue Jan 10, 2017 9:22 pm

When I pack my reflux column I just suck and blow on one end. If I can feel any resistance its too tight.

Cheers Phil
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Re: just repacked a 2" boka now cant get above 92%

Postby Banksy111 » Wed Jan 11, 2017 10:27 pm

Removed around a third of the packing and used low heat got 94%. Getting better now trying higher heat i really want to get 95+ like it did with pot scrubbers.
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Re: just repacked a 2" boka now cant get above 92%

Postby Kenster » Tue Jan 17, 2017 6:53 pm

i am with warra..stainless gave me a metallic after taste...no probs with el-cheapo...SCORIA...love the stuff, works great in my 3''.
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