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Re: [Distillers] Column Packing(The great debate)

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  • Gramps
    G day all,when lime/sulphur spray or dip are used on brass it turn s it s surface into a florentine bronze colour,which is a olde worlde sort of finish.This
    Message 1 of 9 , Nov 1, 2002
      G'day all,when lime/sulphur spray or dip are used on brass it turn's it's surface into a florentine bronze colour,which is a "olde worlde" sort of finish.This was used about 45 years or so ago on cupboard fittings etc.Exactly what the coating consists of I can not say but it surely is an oxide of some description,hope this helps.Regards,Ken.
       
      ----- Original Message -----
      Sent: Friday, November 01, 2002 4:09 PM
      Subject: RE: [Distillers] Column Packing(The great debate)

      They looked too pale to be brass to me. Any idea what they're made out of? (idle curiosity only)
      I've used Goldilocks, and it makes great column packing.  Nice thing about it is that it seems to be reasonably high quality and doesn't corrode or 'rust'.  It will rapidly turn black with sulphides deposited on it, but if you give your column a good steaming and rinse after each run, the color doesn't matter.
       
      All the best,
      Mike N


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    • peter_vcb
      Mike said It tends to clump together quite tightly, like sand, and there would be no room for vapor to pass through. what do you make of this link Mike.
      Message 2 of 9 , Nov 1, 2002
        Mike said "It tends to clump together quite tightly, like sand, and
        there would be no room for vapor to pass through." what do you make
        of this link Mike.

        http://www.engr.pitt.edu/chemical/undergrad/lab_manuals/packed_bed_rev
        _jan02.pdf

        you will probably have to cut and paste that link or go to google and
        search for "glass sand" distillation (it will be the first hit)

        it is a college site talking about using fine glass sand as a packing
        medium in a glass column, small scale. if the power was low enough
        would it be able to make its way through carbon without much trouble?
        if so a good mix would be sand at the bottom and then carbon at the
        top of the column. also if my power is low enough can i tightly pack
        in my scrubbers increasing the HETP?











        --- In Distillers@y..., "Chris de Weyer" <chrissa_am@h...> wrote:
        >
      • bokakob
        You are forgetting about one more indicator called void or free volume or something like this. I think these two materials are on the opposite ends of the
        Message 3 of 9 , Nov 1, 2002
          You are forgetting about one more indicator called "void" or "free
          volume" or something like this. I think these two materials are on
          the opposite ends of the scale in respect to this parameter.
          Cheers, Alex...
        • Mike Nixon
          peter_vcb wrote: Subject: [Distillers] Re: Column Packing(The great debate) Mike said It tends to clump together quite tightly, like sand, and there would be
          Message 4 of 9 , Nov 1, 2002

            peter_vcb wrote:
            Subject: [Distillers] Re: Column Packing(The great debate)

            Mike said "It tends to clump together quite tightly, like sand, and there would be no room for vapor to pass through." what do you make of this link Mike.

            http://www.engr.pitt.edu/chemical/undergrad/lab_manuals/packed_bed_rev_jan02.pdf

            you will probably have to cut and paste that link or go to google and search for "glass sand" distillation (it will be the first hit)

            it is a college site talking about using fine glass sand as a packing medium in a glass column, small scale. if the power was low enough would it be able to make its way through carbon without much trouble? if so a good mix would be sand at the bottom and then carbon at the top of the column. also if my power is low enough can i tightly pack in my scrubbers increasing the HETP?
            ==============================

            Hi Peter,

            That's a very good file, and well worth reading. 
            Two sentences in it are worth highlighting:
            "Ideally, the porosity of the packing should not hinder the gas flow through the column.  In this lab, the packing in the column is glass sand."

            Note that it does not say that the sand is "fine glass sand", just "glass sand".
            I think this comes down to a question of terminology ... specifically "sand" and "porosity".  Having stressed that the packing should not hinder the gas flow, it seems clear that the granules of the "glass sand" they are using must be large enough to permit this, and that would make them fairly large.  I therefore believe that what they are talking about is glass beads ... a common lab packing for small stills.  These are small enough to flow easily into a column and fill it, but big enough to prevent liquid from filling the gaps between them.  The gaps between the beads are the measure of "porosity", not the glass material itself, which is solid.  These small beads look for all the world like the packing you put into a bean bag, but made of glass and not polystyrene.

            Worth noting too that the size of the apparatus they are using would look tiny to us.  We practice what might be termed "small scale distillation".  These guys will be using "micro distillation" gear, with columns only about 20cm long.  These will be run slowly, at very low power, and all they are interested in is getting enough for a sample ... a few milliliters.

            Getting back to this question of putting carbon in a column, you could try it, but I'm prepared to put money on you finding that it does no good at all.  Carbon depends on being immersed in the liquid it is cleaning, to permit free flow of molecules in and out of its structure.  Putting carbon in a column so that it holds only droplets of liquid, and is surrounded by vapor, would not enable it to work properly.  It's a neat idea, to distil and clean at the same time, but I think you would find that it doesn't work in practice.

            All the best,
            Mike N

             

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