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Separate Boiler / Columns

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  • edited February 2015

    Put a valve in the second column drain. Going to measure ABV, taste, smell, when in full reflux and when collecting at high ABV.

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  • good thinking.

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  • Just tested the drain, took fores then put it in full reflux, sample was 30%, very watery tasting, next to no burn. Opened valve and collected at 88%, being a dickhead, I forgot to pack the second column!, took a sample and it was around 80%!, smelt and tasted very similar to what was coming out the parrot. I don't understand what happened, taking at 88%, I thought what would be coming out the drain would be 12% etc!?.

  • edited February 2015

    Off the second with no packing? Dephlegmator running? Would be very similar to the distillate, less some passive mass transfer on the walls and falling condensate.

    However, even if it were packed, given the levels of reflux ratio that we run, it's nearly impossible that you would see 12% in the drain back from the second column, except maybe deep deep deep in tails on low ABV boiler charge. You probably wouldn't even see that on the drain back from the first column.

  • @googe grim is right. The drain and the product don't add up to 100%. The product, what is captured in the column, and the drain add up to 100%.

    If you get it right the drain should not be more than very low ABV.

  • Thanks fellas, I get that, 100% was an example. So, let's say, if im collecting at 88% why is there 80% in the drain?.

  • edited February 2015

    Did you correct for temperature? That range is like a 10c difference (drain hotter than parrot).

  • Yep, best I could, you saying the drain should be the same ABV as takeoff?

  • In this instance googe the 2nd drain will be close to what is being produced from the first column. Even without packing were you still running the dephlegmator on the 2nd column? If so that dephlegmator on its own is acting as a column section.

    One of the early column designs was a thermally jacketed column. We don't tend to think about it, but the dephlegmator is an active device in its own right.

  • Yeah was running the dephleg on the second Myles, I thought you said in a past thread that the ABV from the second drain would be low, so no.need for a drain on the second?.

  • Slight missunderstanding. You need a second column drain because there is a volume of column bottoms to deal with. However that liquid should be very low ABV.

    So in your last run your 1st column was producing vapour at about 80%. You then passed that vapour through a short active device that condensed some of it. Because there was no packing that condensate dropped through the column into the drain.

    Your active device (dephlegmator) lifted your vapour from 80% to 88%. Couldn't do much more because it is short and quite a rudimentary device, but that explains your run performance. Does that help?

  • Makes sense Myles, I waisted my time doing it!.

  • No you didn't. You now know to check the packing is in next time. ;)

    I once did a cleaning run with my dephlegmator on 100% reflux. You would be surprised at how fast I managed to heat up my coolant reservoir. I now know to set an alarm clock when doing that. :))

  • Absolutely brilliant build Googe, really wish I had your skills, well any metalwork skills actually. Have you been able to determine how much volume there was collecting at the bottom of the packed column. I so like the look of the build I'm going to try one in 4" CD with packed section. I am hoping to avoid the flooding of the packed section by having it attached to the top of the boiler instead of the bench hoping the boiler heat would help.

  • I think we've all monad them blonde moments Myles lol. Thanks what. I didn't measure volume at the bottom.of the column, was alot coming out though, more than I thought, but like the progressive, wasn't an optimum experiment without packing!. I recon it would be hard to flood the packed column cause the input to it is high ABV :-?

  • edited February 2015

    @what one of your options with any packed column is to split your reflux return line. This is actually one of the reasons (although I don't often mention it) why I like the offset condenser designs.

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    OK I will admit that I never fully trialed the idea of adjusting the split in reflux return between the top and bottom of the column. However, in principle you can split your dephlegmator condensate. This was in reality a trial to divert all of the condensate to the top OR bottom of the column.

    I did try to create a split between the two, but the ball valve was the wrong choice. A gate valve would have been a more controllable option for that application.

    I never bothered, but if you are going to run any column at close to its maximum potential product speed, you are going to hit the column flood condition. This is the one situation when it really does make sense to get some of the dephlegmator condensate out of the column, and divert it directly back to the boiler.

    This might not be a real issue with a plated column, but it can be one with a packed column. If you are going to use a packed section at high power levels, you may wish to think about managing your reflux return paths.

    But again, this may be a VM specific problem, and it could be not relevant to a CM column.

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  • Brilliant idea Myles, I'm just in the process of working out the condenser now. Was thinking about something horizontal that might feed both.

  • @what said: I'm just in the process of working out the condenser now. Was thinking about something horizontal that might feed both.

    You do realise you just opened a can of worms? :)) In principle with 2 columns the dephlegmator on the second column could feed reflux to the first. But it would be higher proof than it would "expect". Not entirely sure what it would do, but I am sure it would still stabilise. A horizontal condenser over a column is a good way to reduce height though.

  • edited April 2015

    Just did a test with the second drain again, with packing this time lol. Was taking off at over 96%, first time.ever!. The sample.from the drain was 80%. Same ABV as taking off at 88%. Got no idea. Also did some speed testing, rum at 90% at 3.7lph, and neutral at 96% at 4.2lph, been running it to slow!!.

  • More vapor= more reflux=more purity.

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  • edited April 2015

    Drain abv will never be low with the reflux ratios we run, you'd need 30+ plates and a mid-column feed to have a drain abv lower than the boiler charge abc (with reboiler, etc etc). The higher the reflux ratio, the higher the drain abv. If you are pushing higher reflux ratios to pull a higher purity with fewer plates, I reckon your drain ABV will be very close to your take off (or at least closer to your take off than your boiler charge).

    In this situation, you really aren't talking about developing any kind of temperature gradient up through the plates, you are really just loading all the plates with the highest abv in order to push take off abv to the max. Sure, this might be less efficient, but who cares?

  • Excellent Googe. Love what you're doing :-bd

  • edited April 2015

    Makes sense @Smaug, every time I pushed my last still on the boiler it always dropped ABV or flooded, I must have had it running just right with this setup, I could hear the lava bouncing around. I sort of get what your saying @grim, but still don't understand why the ABV on the drain was the same at 90% take off as it was at 96% takeoff, are you saying no matter the plate numbers or ABV take off, its about the reflux ratio? Thanks @captainshooch!

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