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Re: [Distillers] Re: Theoretical plates in a whisk(e)y still?

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  • zapatavive@suddenlink.net
    Very useful. I didn t know that the vast majority of whiskey was made in columns. Honestly though I was thinking of scotch whisky stills in particular, and
    Message 1 of 14 , Jan 4, 2009
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      Very useful. I didn't know that the vast majority of whiskey was made in columns. Honestly though I was thinking of scotch whisky stills in particular, and assumed bourbon et al was made in similar stills.

      So I guess I have 2 questions, if I'm not mistaken, the Scots do use pot style stills, right? And if so, could we guess how much reflux happens in the large tops on those stills?

      For example, there are no physical plates in this still, are there?
      http://www.scotchwhisky.net/images/dist/glendronach_still.jpg
      If not, surely a lot of reflux happens in there, right?

      Or these:
      http://www.lochlomonddistillery.com/assets/Images/malt1.jpg
      http://www.popsci.com/files/imagecache/article_image_large/files/articles/Ardmore%20Distillery%20-%20Stills.jpg

      Thanks Harry!
      ---- Harry <gnikomson2000@...> wrote:
      > --- In Distillers@yahoogroups.com, "Zapata Vive" <zapatavive@...> wrote:
      > >
      > <snip>
      >
      > none of the literature that I've read gives any indication for how much
      > reflux occurs in commercial whiskey stills, just that some does, and
      > the amount varies from still to still and distillery to distillery.
      > >
      > > So, any ideas how much reflux is going on in those big whiskey stills?
      >
      >
      >
      > There are no 'theoretical plates' in a plate column. They are actual
      > physical plates or trays. Whiskey columns are too big to use packing
      > instead of plates.
      >
      > Are you referring to whiskey plate columns or whiskey pot stills? To
      > my knowledge there's only one (1) whiskey produced commercially that is
      > pot distilled and that's Woodford Reserve Bourbon.
      >
      > All the rest use plate column designs. As such, the reflux ratio must
      > be a certain minimum to maintain steady balanced column action. This
      > minimum is somewhere in the region of 2:1 or 3:1 reflux:product ratio.
      > Less is bad, more is bad.
      >
      > If a particular plate runs low on liquid due to too little reflux
      > return, the column is in danger of "dumping". This will require a
      > restart and once again bringing the column to equilibrium.
      >
      > If there's too much reflux liquid returned, then pressure buildup,
      > surging and temperature fluctuation between plates drastically reduces
      > efficiency, and the product quality is poor.
      >
      > IOW, for plate columns it's all a balancing act.
      >
      > Hope that is useful.
      >
      >
      > Slainte!
      > regards Harry
      >
    • zapatavive@suddenlink.net
      Very useful. I didn t know that the vast majority of whiskey was made in columns. Honestly though I was thinking of scotch whisky stills in particular, and
      Message 2 of 14 , Jan 4, 2009
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        Very useful. I didn't know that the vast majority of whiskey was made in columns. Honestly though I was thinking of scotch whisky stills in particular, and assumed bourbon et al was made in similar stills.

        So I guess I have 2 questions, if I'm not mistaken, the Scots do use pot style stills, right? And if so, could we guess how much reflux happens in the large tops on those stills?

        For example, there are no physical plates in this still, are there?
        http://www.scotchwhisky.net/images/dist/glendronach_still.jpg
        If not, surely a lot of reflux happens in there, right?

        Or these:
        http://www.lochlomonddistillery.com/assets/Images/malt1.jpg
        http://www.popsci.com/files/imagecache/article_image_large/files/articles/Ardmore%20Distillery%20-%20Stills.jpg

        Thanks Harry!
        ---- Harry <gnikomson2000@...> wrote:
        > --- In Distillers@yahoogroups.com, "Zapata Vive" <zapatavive@...> wrote:
        > >
        > <snip>
        >
        > none of the literature that I've read gives any indication for how much
        > reflux occurs in commercial whiskey stills, just that some does, and
        > the amount varies from still to still and distillery to distillery.
        > >
        > > So, any ideas how much reflux is going on in those big whiskey stills?
        >
        >
        >
        > There are no 'theoretical plates' in a plate column. They are actual
        > physical plates or trays. Whiskey columns are too big to use packing
        > instead of plates.
        >
        > Are you referring to whiskey plate columns or whiskey pot stills? To
        > my knowledge there's only one (1) whiskey produced commercially that is
        > pot distilled and that's Woodford Reserve Bourbon.
        >
        > All the rest use plate column designs. As such, the reflux ratio must
        > be a certain minimum to maintain steady balanced column action. This
        > minimum is somewhere in the region of 2:1 or 3:1 reflux:product ratio.
        > Less is bad, more is bad.
        >
        > If a particular plate runs low on liquid due to too little reflux
        > return, the column is in danger of "dumping". This will require a
        > restart and once again bringing the column to equilibrium.
        >
        > If there's too much reflux liquid returned, then pressure buildup,
        > surging and temperature fluctuation between plates drastically reduces
        > efficiency, and the product quality is poor.
        >
        > IOW, for plate columns it's all a balancing act.
        >
        > Hope that is useful.
        >
        >
        > Slainte!
        > regards Harry
        >
      • Harry
        ... in columns. Honestly though I was thinking of scotch whisky stills in particular, and assumed bourbon et al was made in similar stills. ... pot style
        Message 3 of 14 , Jan 4, 2009
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          --- In Distillers@yahoogroups.com, <zapatavive@...> wrote:

          >
          > Very useful.  I didn't know that the vast majority of whiskey was made in columns.  Honestly though I was thinking of scotch whisky stills in particular, and assumed bourbon et al was made in similar stills.
          >
          > So I guess I have 2 questions, if I'm not mistaken, the Scots do use pot style stills, right?  And if so, could we guess how much reflux happens in the large tops on those stills?
          >
          > For example, there are no physical plates in this still, are there?
          > http://www.scotchwhisky.net/images/dist/glendronach_still.jpg
          > If not, surely a lot of reflux happens in there, right?
          >
          > Or these:
          > http://www.lochlomonddistillery.com/assets/Images/malt1.jpg
          > http://www.popsci.com/files/imagecache/article_image_large/files/articles/Ardmore%20Distillery%20-%20Stills.jpg
          >
          > Thanks Harry! 

           

          Heh, ya dinna hae ta tell me twice!  :)

          First let me say this...the Scotch pot stills of today are a far cry technically from their ancestors, even though they appear similar to the eye.  Modern innovations like gas-fired steam heating (replacing 'direct' firing) and electronic monitoring, plus 'shell & tube' condensers replacing the old 'worm' condensers, and GC analysis makes for a far more precise product than ever before.

          Couple this with the modern taste for 'blended' malts like Ballantyne's (requires 42 different single malts) and you have a myriad of variables to get your head around.

          But that doesn't answer your question.  So I'll give you an extract from a recent collaborative paper between Bruichladdich Distillery on Islay in Scotland, and University of Tennessee, Knoxville, TN 37996-2200, USA.


          <extract>

          Still Construction and Shape:

           The pressure profile in pot stills has an influence

          on the vaporization and condensation of the lower vapor pressure components.

          Reductions in pressure lower the boiling point of all components and increases in

          pressure enhance the condensation of these same components on the interior walls of the

          stills. The construction and shape of the stills should have a noticeable effect on the

          spirits produced. The copper construction enables excellent heat transfer through the still

          causing the less volatile, i.e. higher boiling, components to condense on the cooler sides

          of the still and return to the boiling liquid.

          In the modeling of the stills using HYSYS engineering software, it was found that

          assuming that the stills were composed of eight equivalent stages and a reflux ratio of one

          fourth of the vapor phase was appropriate to fit the data [Rogers 2004]. As noted

          in the

          temperature profile data the external surface of the copper stills in the vapor phase region

          is significantly cooler than the boiling liquid and this temperature is not strongly

          dependent upon the height above the boiling liquid. The vapor condensate that forms on

          the still surfaces is enhanced in composition of the higher temperature boiling, i.e. less

          volatile component, compared to the vapor from which it condenses. This results in

          reflux of the less volatile components thereby enriching the vapor phase that reaches the

          condensers in a manner similar to that in a tray or packed column in which the

          rising

          vapor phase is contacted with falling liquid phase. Therefore the condensate on the

          interior of the still should have a higher concentration of the lower vapor pressure or

          higher boiling components. The copper construction of the still enables the removal of

          sulfur compounds from the distillate by forming copper sulfates that precipitate out and

          are not carried over into the final spirits.

          The height and degree of contraction of the stills affect the surface area for

          contact with and repeated enrichment of the rising vapor. Furthermore, the manner in

          which the stills contract can also have an influence. The Bruichladdich stills have a

          smooth transition from the pot to the neck. Stills that have a significant contraction and

          then expansion above the liquid level can induce a venturi effect in which the vapor is

          accelerated and then decelerated in its upward motion. If there is a constant mass flow

          rate through a venturi, the fluid's average velocity is increased due to the reduction in

          cross sectional area and the associated increase in kinetic energy causes a reduction in

          pressure, i.e. pressure volume energy is converted to kinetic energy in the contraction and

          then the pressure is recovered as the cross section increases. The decrease in pressure

          begins prior to the rapid contraction and if the boiling liquid level is near the significant

          contraction, the pressure is lowered and the boiling point of the components lowered.

          This in turn causes the lower vapor pressure components to be included in the vapor at a

          lower temperature but as the cross sectional area expands these components will be more

          prone to condensation on the interior surface of the still and a higher effective reflux

          ratio. As the liquid level recedes during a run the effect on the boiling is also decreased

          even though the pressure changes in the venturi section are not. Stills for which a bulge

          occurs above the boiling liquid have an opposite effect to the venturi: increased pressure

          preceding the bulge and decreased in the bulge. The pressure profile will also be

          influenced by the general contraction effect in the onion shaped stills and this in turn will

          affect the condensation and reflux on the interior surface of the still.

          </extract>

           

           

          Now, when they say "reflux ratio of one fourth of the vapor phase", bear in mind that the vapour phase has 45 times the volume of the equivalent liquid phase.  This may be useful for those trying to guesstimate, measure or equate detuned LM /VM style rigs as whisky stills.

          So, there you have it.

          Slainte!
          regards Harry

        • abbababbaccc
          Aha, the great Harry has given incomplete answer so here s my change to nitpick :) Some Irish whiskeys are also made in potstills, both double and triple
          Message 4 of 14 , Jan 4, 2009
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            Aha, the great Harry has given incomplete answer so here's my change
            to nitpick :) Some Irish whiskeys are also made in potstills, both
            double and triple distilled.

            Cheers, Riku

            --- In Distillers@yahoogroups.com, "Harry" <gnikomson2000@...> wrote:
            >
            >
            >
            > There are no 'theoretical plates' in a plate column. They are
            actual
            > physical plates or trays. Whiskey columns are too big to use
            packing
            > instead of plates.
            >
            > Are you referring to whiskey plate columns or whiskey pot stills?
            To
            > my knowledge there's only one (1) whiskey produced commercially
            that is
            > pot distilled and that's Woodford Reserve Bourbon.
            >
            > All the rest use plate column designs. As such, the reflux ratio
            must
            > be a certain minimum to maintain steady balanced column action.
            This
            > minimum is somewhere in the region of 2:1 or 3:1 reflux:product
            ratio.
            > Less is bad, more is bad.
            >
            > If a particular plate runs low on liquid due to too little reflux
            > return, the column is in danger of "dumping". This will require a
            > restart and once again bringing the column to equilibrium.
            >
            > If there's too much reflux liquid returned, then pressure buildup,
            > surging and temperature fluctuation between plates drastically
            reduces
            > efficiency, and the product quality is poor.
            >
            > IOW, for plate columns it's all a balancing act.
            >
            > Hope that is useful.
            >
            >
            > Slainte!
            > regards Harry
            >
          • zapatavive@suddenlink.net
            Now that was exactly what I wanted to read! Thank you once again kind sir!
            Message 5 of 14 , Jan 5, 2009
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              Now that was exactly what I wanted to read! Thank you once again kind sir!

              ---- Harry <gnikomson2000@...> wrote:

              >
              > Heh, ya dinna hae ta tell me twice! :)
              >
              > First let me say this...the Scotch pot stills of today are a far cry
              > technically from their ancestors, even though they appear similar to the
              > eye. Modern innovations like gas-fired steam heating (replacing
              > 'direct' firing) and electronic monitoring, plus 'shell & tube'
              > condensers replacing the old 'worm' condensers, and GC analysis makes
              > for a far more precise product than ever before.
              >
              > Couple this with the modern taste for 'blended' malts like Ballantyne's
              > (requires 42 different single malts) and you have a myriad of variables
              > to get your head around.
              >
              > But that doesn't answer your question. So I'll give you an extract from
              > a recent collaborative paper between Bruichladdich Distillery on Islay
              > in Scotland, and University of Tennessee, Knoxville, TN 37996-2200, USA.
              >
              >
              > <extract>
              >
              >
              > Still Construction and Shape:
            • waljaco
              Most scottish whisky stills are ex-gin stills from England. Most whisky is blended whisky i.e. pot still (malt whisky) and Coffey (column) still (grain whisky)
              Message 6 of 14 , Jan 5, 2009
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                Most scottish whisky stills are ex-gin stills from England. Most whisky is
                blended whisky i.e. pot still (malt whisky) and Coffey (column) still (grain
                whisky) products. Most grain whisky goes to english gin manufacturers. Use
                abv output as your guide for a pot still.
                wal
                --- In Distillers@yahoogroups.com, "Zapata Vive" <zapatavive@...> wrote:
                >
                > Actually I'm wondering about whiskey and whisky stills, not pot stills. Yes, a
                pot still = 1 plate, pretty much by definition. But a huge copper pot, only half
                full, with an exaggerated tapering top, no insulation, and a lyne arm that
                sometimes slopes up, does not make a simple pot still. Maybe the "theoretical
                plates" are less than 2, but surely more than 1. If not, why don't they just use
                flat topped perfectly insulated boilers with just enough headspace to keep the
                foam under control?
                >
                > You're a pro though, so I won't pull any quotes that discuss the reflux that
                occurs in whiskey stills, as I'm sure you've read more than I have on the
                subject. But none of the literature that I've read gives any indication for how
                much reflux occurs in commercial whiskey stills, just that some does, and the
                amount varies from still to still and distillery to distillery.
                >
                > So, any ideas how much reflux is going on in those big whiskey stills?
                >
                > ----- Original Message -----
                > From: Harry
                > To: Distillers@yahoogroups.com
                > Sent: Tuesday, December 30, 2008 3:17 AM
                > Subject: [Distillers] Re: Theoretical plates in a whisk(e)y still?
                >
                >
                > --- In Distillers@yahoogroups.com, "Zapata Vive" <zapatavive@> wrote:
                > >
                > > Anybody have any idea how how many theoretical plates there are in
                > whisky or whiskey stills? There is some reflux going on in those
                > beautiful pots and lynes, but just how much? Any good guesses out
                > there?
                > >
                >
                > Column stills = however many physical plates are put in them (more than
                > 10)
                >
                > Brandy stills (eau-de-vie) = 3 to 5 physical plates
                >
                > But you were referring to pot stills, yes?
                >
                > Pot still = 1 plate
                >
                > Pot still + 1 thumper = 2 plates
                >
                > Pot still + 2 thumpers = 3 plates
                >
                > Getting the pattern?
                >
                > Whiskies are usually charged to the spirit still (2nd still) at 27-30%
                > a/v. Then given a single distillation, which yields potable spirit at
                > around 70+% a/v.
                >
                > Use Tony's site to get a handle on this.
                > Try the first calculator at 30% and 1 plate.
                > http://homedistiller.org/refluxdesign.htm
                >
                > Slainte!
                > regards Harry
                >
              • Harry
                ... Are you talking pot stills or columns, Wal? 50% of all Scottish pot stills are built by Forsyth s of Rothe. Pot stills require the boiler to be replaced
                Message 7 of 14 , Jan 5, 2009
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                  --- In Distillers@yahoogroups.com, "waljaco" <waljaco@...> wrote:
                  >
                  > Most scottish whisky stills are ex-gin stills from England.


                  Are you talking pot stills or columns, Wal?

                  50% of all Scottish pot stills are built by Forsyth's of Rothe. Pot
                  stills require the boiler to be replaced each 25 years, the upper
                  parts each 10-15 years.
                  http://www.thewhiskystore.de/experts/copper.htm

                  For a good description of the birth in 1955 (and subsequent demise in
                  the 1980's) of the experimental Lomond still of Hiram Walker, see
                  here...
                  http://tinyurl.com/7m48ta


                  "There are two main types of Scotch whisky, which in turn can be
                  combined to give further types. Malt whisky can contain no grain
                  other than malted barley, and is almost always distilled in batches
                  in traditional distilleries in pot stills. Grain whisky can be made
                  from unmalted barley or other malted or unmalted grains like wheat
                  and maize. It is usually distilled in industrial-scale continuous
                  column stills called Coffey Stills. There are currently around 100
                  active malt whisky distilleries in Scotland, with several more being
                  planned or built. This compares with just seven grain distilleries in
                  Scotland, though each of these has an output far larger than most
                  malt distilleries."
                  [Source:
                  http://www.undiscoveredscotland.co.uk/usscotfax/ent/whisky.html%5d

                  Slainte!
                  regards Harry
                • waljaco
                  When gin drinking was suppressed in England the frugal Scots bought up the pot stills - some have/had a limited reflux in the manner of a Moor s Head still.
                  Message 8 of 14 , Jan 7, 2009
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                    When gin drinking was suppressed in England the frugal Scots bought
                    up the pot stills - some have/had a limited reflux in the manner of a
                    Moor's Head still.
                    The frugal Scots also use second-hand barrels to store their product!
                    wal
                    --- In Distillers@yahoogroups.com, "Harry" <gnikomson2000@...> wrote:
                    >
                    > --- In Distillers@yahoogroups.com, "waljaco" <waljaco@> wrote:
                    > >
                    > > Most scottish whisky stills are ex-gin stills from England.
                    >
                    >
                    > Are you talking pot stills or columns, Wal?
                    >
                    > 50% of all Scottish pot stills are built by Forsyth's of Rothe. Pot
                    > stills require the boiler to be replaced each 25 years, the upper
                    > parts each 10-15 years.
                    > http://www.thewhiskystore.de/experts/copper.htm
                    >
                    > For a good description of the birth in 1955 (and subsequent demise in
                    > the 1980's) of the experimental Lomond still of Hiram Walker, see
                    > here...
                    > http://tinyurl.com/7m48ta
                    >
                    >
                    > "There are two main types of Scotch whisky, which in turn can be
                    > combined to give further types. Malt whisky can contain no grain
                    > other than malted barley, and is almost always distilled in batches
                    > in traditional distilleries in pot stills. Grain whisky can be made
                    > from unmalted barley or other malted or unmalted grains like wheat
                    > and maize. It is usually distilled in industrial-scale continuous
                    > column stills called Coffey Stills. There are currently around 100
                    > active malt whisky distilleries in Scotland, with several more being
                    > planned or built. This compares with just seven grain distilleries in
                    > Scotland, though each of these has an output far larger than most
                    > malt distilleries."
                    > [Source:
                    > http://www.undiscoveredscotland.co.uk/usscotfax/ent/whisky.html%5d
                    >
                    > Slainte!
                    > regards Harry
                    >
                  • justin webster
                    hello people, didn t get any bites on the newdistillers list so I m hoping one of you chaps will have some ideas on this: I recently inherited a hand
                    Message 9 of 14 , Jan 8, 2009
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                      hello people,
                      didn't get any bites on the newdistillers list so I'm hoping one of
                      you chaps will have some ideas on this:

                      I recently inherited a hand refractometer which I excitedly put to use
                      on several brews.
                      I was hoping that a combination of SG and Brix would give me a better
                      estimation of alcohol content in the beer.
                      what I have noticed is that my calculations of sugar/alcohol content
                      using the refractometer readings are quite different from those using
                      specific gravity.
                      of course I expected there to be a difference but not to such an extent.

                      here are some numbers from a recent rum batch:
                      calc Brix by volume 25
                      actual Brix start 23
                      actual Brix end 7
                      SG start 1.090
                      SG end .994
                      potential ABV (vol) 14.7
                      potential ABV (Brix) 13.53
                      actual ABV (SG) 12.384
                      actual ABV (Brix) 9.411

                      now I am aware that I have not been fermenting out all sugars
                      (slightly lazy with temperature and Ph management) but I think the SG
                      numbers seem about right.
                      it sure seems like I can never get a brix reading under 7 or 8. this
                      was true with palm sugar washes as well as my recent rum batches.
                      I'm wondering if all the other by-products of fermentation (yeast in
                      particular) would bias the brix reading to a greater extent than the SG.

                      both hydrometer and refractometer seem to be calibrated correctly and
                      I'm pretty sure my math is solid.

                      so can a refractometer be trusted?

                      justin
                    • harisaki2004
                      Justin, I have tried using a refractometer for wine, but is inaccurate because you are dealing with sugar and alcohol based liquid. Stick with hydrometers this
                      Message 10 of 14 , Jan 8, 2009
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                        Justin,

                        I have tried using a refractometer for wine, but is inaccurate because
                        you are dealing with sugar and alcohol based liquid. Stick with
                        hydrometers this is what the industry uses.

                        Refractometers are OK for mono liquids not binary liquids.

                        regards

                        Hari.


                        --- In Distillers@yahoogroups.com, justin webster <mail@...> wrote:
                        >
                        > hello people,
                        > didn't get any bites on the newdistillers list so I'm hoping one of
                        > you chaps will have some ideas on this:
                        >
                        > I recently inherited a hand refractometer which I excitedly put to use
                        > on several brews.
                        > I was hoping that a combination of SG and Brix would give me a better
                        > estimation of alcohol content in the beer.
                        > what I have noticed is that my calculations of sugar/alcohol content
                        > using the refractometer readings are quite different from those using
                        > specific gravity.
                        > of course I expected there to be a difference but not to such an extent.
                        >
                        > here are some numbers from a recent rum batch:
                        > calc Brix by volume 25
                        > actual Brix start 23
                        > actual Brix end 7
                        > SG start 1.090
                        > SG end .994
                        > potential ABV (vol) 14.7
                        > potential ABV (Brix) 13.53
                        > actual ABV (SG) 12.384
                        > actual ABV (Brix) 9.411
                        >
                        > now I am aware that I have not been fermenting out all sugars
                        > (slightly lazy with temperature and Ph management) but I think the SG
                        > numbers seem about right.
                        > it sure seems like I can never get a brix reading under 7 or 8. this
                        > was true with palm sugar washes as well as my recent rum batches.
                        > I'm wondering if all the other by-products of fermentation (yeast in
                        > particular) would bias the brix reading to a greater extent than the SG.
                        >
                        > both hydrometer and refractometer seem to be calibrated correctly and
                        > I'm pretty sure my math is solid.
                        >
                        > so can a refractometer be trusted?
                        >
                        > justin
                        >
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