Critical Eye

edited August 2015 in Configuration

Can someone please run a critical eye over this multi column design.
I want to add a VM column to the existing 4" CD.
Cheers

image

Comments

  • What stops the vapour from going back up to the RC after the column rather than down to the PC? Just gravity?

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • How does the reflux get in the packed section?
    What's the small line returning reflux to the boiler for?
    I'm not seeing it but maybe a description would help.

  • @punkin said: What stops the vapour from going back up to the RC after the column rather than down to the PC? Just gravity? Yes just gravity, was trying to avoid another valve, I was thinking the only other option would be change the PC to a side entry condenser like the RC, keep the top connection and have the VM on its own dedicated side entry.

    @jacksonbrown said: How does the reflux get in the packed section?
    What's the small line returning reflux to the boiler for?
    I'm not seeing it but maybe a description would help

    Sorry should have posted a description. Column 1 is a 6 plate 4" CD with a LM heads trap under the RC. Trap is a cut down 2" tee, bottom of the trap has a drain out to a 3 way valve which can be opened to take fores and heads or direct the liquid reflux to the collection cylinder at the bottom of column 2. The cylinder extendes down into the boiler by half its depth but is not open to it, the idea is that the liquid reflux coming from column 1 will flash boil and rise into the VM column 2 I have no control over the liquid reflux falling naturally from column 2 but I can control the volume going to the cylinder from column 1 with the 3 way valve on the heads trap to make sure the base of column 2 does not flood. Well that's the theory anyway.

  • Column 2 must have a way of removing accumulated bottoms, else it will flood regardless.

  • So my understanding of a heads trap is it needs to be at the top of the system with the RC and there must be packing between it and the take off. It’s that packing that does the ‘trapping’ not the reservoir itself. Without the packing (or plates) to hold the heads in place they just overflow and you’ve effectively made a smearing device. An often missed point.

    The collection at the bottom of 2 is a bit flawed too IMO. I don’t think it will flash off like your hoping most likely it will just flood. If the packed column is pulling water out of the vapour, where is all that built up water going to go in your system?

    I don’t understand the vapour bypass about the two linked valves either

    Seems very disjointed to me. It might work but I wouldn’t be confident in it.

    What are you actually trying to do? You want a VM but you want to utilise your plates as part of the total column length?? I’m sure there is a much easier, cheaper and more effective way. You could even run a packed CM, just gut the plates out of your CD.

  • @Harry said: Column 2 must have a way of removing accumulated bottoms, else it will flood regardless.

    @jacksonbrown said: So my understanding of a heads trap is it needs to be at the top of the system with the RC and there must be packing between it and the take off. It’s that packing that does the ‘trapping’ not the reservoir itself. Without the packing (or plates) to hold the heads in place they just overflow and you’ve effectively made a smearing device. An often missed point.

    The collection at the bottom of 2 is a bit flawed too IMO. I don’t think it will flash off like your hoping most likely it will just flood. If the packed column is pulling water out of the vapour, where is all that built up water going to go in your system?

    I don’t understand the vapour bypass about the two linked valves either

    Seems very disjointed to me. It might work but I wouldn’t be confident in it.

    What are you actually trying to do? You want a VM but you want to utilise your plates as part of the total column length?? I’m sure there is a much easier, cheaper and more effective way. You could even run a packed CM, just gut the plates out of your CD.

    Thanks guys! This is why I should always ask, the thought of where the water at the bottom of column 2 would go never even crossed my mind Doh!

    JB I must be missing the point about the smearing, will the heads not collect in the trap under the PC? Once the trap is full it overflows down to the top plate and cycles until such time the trap is eventually full of heads. Crap have I missed something else basic??

    Yes I am trying to utilise the plates as part of the total column length and the RC to do double duty above the plates and for the VM. It all really hinges in how much heat is needed to vaporise the higher poof liquid in collector at the bottom column 2 To make it work I will obviously have to install at the base of column 2 a way of separating and draining back to the boiler the falling water from the rising vapour.

  • edited August 2015

    Just steal Larry's design. Guarantee you won't be the only one! :))

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • edited August 2015

    With a proper heads trap you can take of clean product with the heads still trapped in the still.
    What you have is just an LM, not a heads trap and if your taking heads out before product the LM bit is a bit superfluous, just use the VM.
    The more mass you hold in the reservoir the more 'watered down' the heads become, smearing.
    One of the two main downsides on an LM.
    You don't need the bottom of 2 to flash off if your feeding it vapour. It won't work anyway if the bp isn't well below the boiler temp.
    You'll need reflux at the top of 2 and draining 2 back to the boiler is extreamly inefficient. The benenfit of a few extra plates in the first column is compleatly lost by losing all that high ABV back to the boiler.
    I'd do most of differently :D

  • @jacksonbrown said: With a proper heads trap you can take of clean product with the heads still trapped in the still.
    What you have is just an LM, not a heads trap and if your taking heads out before product the LM bit is a bit superfluous, just use the VM.
    The more mass you hold in the reservoir the more 'watered down' the heads become, smearing.
    One of the two main downsides on an LM.
    You don't need the bottom of 2 to flash off if your feeding it vapour. It won't work anyway if the bp isn't well below the boiler temp.
    You'll need reflux at the top of 2 and draining 2 back to the boiler is extreamly inefficient. The benenfit of a few extra plates in the first column is compleatly lost by losing all that high ABV back to the boiler.
    I'd do most of differently :D

    Thanks JB it's starting to make more sense

Sign In or Register to comment.