Re: what are plates?
- Thanks for your reply. I have done whiskey for years and now am trying my hand at vodka. I guess I should get down to brass tacks. I would like to run somewhere around 300 gallons of strained wash with an alcohol content of around +- 15%. For these amounts would plates or packing be best for a high purity? Can I distill one time with enough height ( packing or plates ) or would it have to be distilled twice to achieve vodka grade purity?
I'm sure these questions sound stupid. I've run a pot still with 2 thumpers for years. I'm still trying to get a grasp on this whole column thing.
--- In firstname.lastname@example.org, "jamesonbeam1" <jamesonbeam1@...> wrote:
> Welp Whiskey,
> Plates are great for eating or in distilling, you can make a column with
> copper perforated plates about every 1/2 foot with a glass view port
> that will cause an evaporation with each plate. This is called a
> fractioning still. Now in columns that are packed with copper
> scrubbers or copper mesh packing, (stainless steel can work but copper
> is better), you can, by the diameter of the column and amount of
> packing, make what are called HEPTs or Height Equivalent to a
> Theoretical Plate,
> This will produce the same effect of multiple distillations within a
> single run in a reflux still verus using a pot still which will only
> give you a single distillation per run. Theres some really good
> information on designing a column with packing to simulate HEPTs on
> Tony's site at: http://www.homedistiller.org/refluxdesign.htm#hetp
> <http://www.homedistiller.org/refluxdesign.htm#hetp> Here is an expert
> from it.
> Read thru this and let us know if you have any questions. Happy New
> JB. aka Waldo.
> Note: The Graph on plates and amount of distillations relating to the
> purity or ABV of alcohol will show you what we are talking about....
> Read this part.
> Thanks to Chris Noonan for helping do this Applet.
> You can see that due to the shape of the curve, most of the gains are
> early on; to get to the really high % purity, you need to take lots of
> steps later on. There is no way around this. If you want high purity,
> you have to work hard for it. Also note (particularly for inefficient
> columns with the equivalent of only 1-2 plates) that the starting % can
> also affect the final % achieved - hence a good idea to use the better
> Each of these "steps" represents an "ideal plate" where enough mingling
> of liquid & vapour allows them to come to equilibrium. If you don't
> allow enough mingling (equilibrium), then you won't achieve a full
> step, but end up a little shy of the target. You get the first step free
> - its the boiler/pot.
> Basically, off a 10% wash
> 1 = 53%
> 2 = 80%
> 3 = 87%
> 4 = 90%
> 5 = 92%
> 6 = 92.6%
> 7 = 93.3%
> 8 = 93.8%
> 9 = 94.2%
> 10 = 94.4%
> One way of doing these steps is to do many single distillations, collect
> the vapour that comes off, condense it, clean out the still, and run it
> through the still again. This why pot stillers do double & triple
> distillations to get into the 80+ % range. But a Reflux column allows
> this to happen continuously; if given enough surface area to equilibrate
> on, the vapour can have gone through multiple distillations by the time
> it gets to the top of the column.
> For each plate to work, it has to be at a particular temperature,
> slightly cooler than the one below, and warmer than the one above. Only
> then will it achieve its equilibrium and an increase in the alcohol
> purity. The differences are really fine too its all happening only
> between 78.1 C and 82.2 C quite a tight band to walk between.
> Mike Nixon explains in a bit more detail ...
> The process of separation depends on two facts:
> 1) when a vapor condenses then the resulting liquid has the same
> composition as the vapor, and the temperature at which this occurs is
> the same as the boiling point of that mixture. The boiling point lowers
> as the proportion of volatiles increases, so the temperature as you go
> up a column naturally decreases. One sticking point is that many think
> that a vapor only condenses when it encounters a surface that is cooler
> than the boiling point, but this is not so. Condensation occurs when
> there is a path for the latent heat of vaporization/condensation to be
> removed from the vapor, and the resulting liquid will remain at its
> boiling point if no further heat is removed.
> 2) when this liquid re-evaporates then the resulting vapor is richer in
> the most volatile components.
> The packing is there simply to hold intermediate distillate in place so
> it can be bathed in hot, rising vapor and allow this second process to
> occur. As volatiles are further extracted from the intermediate
> distillate, the boiling point of what remains increases and the depleted
> liquid builds up, eventually dripping down the packing to a hotter level
> where it can again be stripped of more volatiles.
> A cooling tube placed near the bottom of a column simply interrupts this
> natural progression and serves no useful purpose in the separation
> process. In contrast, the top cooling tube IS useful as it helps to
> return some of the vapor arriving at the top of the column to the
> packing, where it has a further chance of being stripped more
> thoroughly. This is what a condenser placed on top of a compound column
> does, but with more efficiency.
> This is where the various designs that have cooling tubes running
> through their columns at all different heights (eg Labmaster) come
> adrift they don't allow the required sequence of temperatures
> to develop fully, and thus won't work at their full potential. They
> also don't allow all the refluxed liquid to do its job over the
> packing the less liquid/vapour contact the poorer the "polishing"
> of the vapour will be.
> This is why you should also (see my interactive Heat & Mass Balance
> <http://www.homedistiller.org/heatmass.htm> page to play with these and
> see it for yourself):
> * Insulate the column well (don't want breezes causing additional
> cooling out of sequence), * Let the column run at total reflux for a
> while (to allow the packings to heat up to their equilibrium
> temperature). This is also important so that the methanol is given a
> chance to all work its way to the top of the column, so that it will all
> come off in the first off-take, * Only have condensors for reflux
> above the packing, and * Use a stable/continuous heat source (you
> don't want it switching off & on all the time causing surges of
> vapour going up the column then periods of nothing; it has to be a
> steady continuous flow of vapour & liquid)
> So you can easily work out what is required to get a particular %
> purity; just look up the number of ideal plates needed, eg 2 plates =
> 87%, 3=90%, 4=92% and so on. Remember you get the first one free - its
> the pot.
> A pot still is the equivalent of a single plate; if it has "thumpers"
> attached to it, each of these can act as an extra plate.
> Why call them plates ? In large distillation columns, they are exactly
> that; large metal plates or trays, which the liquid flows over, and the
> gas bubbles up through holes in them. However they are quite tricky to
> design & build, and not really suited for small column diameters (say
> less than 1 ft diameter) - they're just too fiddly. Below this size,
> its easier to use a Packed Column; where the packing can be random (eg
> just dumped in there and given a shake), or carefully positioned &
> stacked . For any particular type of packing, we can estimate how much
> of it is required to make one of these "ideal plates". See
> <http://www.5continentsusa.com/cer-pack.htm> for examples of different
> commercially available types of packing. These commercial packings are
> quite difficult to source, then expensive to purchase. They're designed
> for an industrial operation, where they're expected to be run
> continuously 24/7 for weeks or months at a time without fouling up. For
> a hobby distiller it is far easier, and with higher performance
> (%purity), to use common pot scourers (non-rusting stainless steel or
> copper) instead for packing, as we'll be cleaning them frequently (like
> after every 20L run).
> Jim adds:
> While gathering materials for my (first) reflux still, I came across an
> interesting material used for making batteries. It's a fine-mesh
> expanded metal made from copper by the Exmet Corporation. They make
> expanded metal from a variety of metals besides copper in sheets varying
> in width from .099 in. to 60 in.
> Their spec sheet is found at: http://www.exmet-corp.com/chart.html
> I don't know how you would calculate the void to surface ratio to get
> optimum results. I leave that to the "experts".One could roll a 30" wide
> sheet, for example, into a single piece that could be inserted into the
> column. It would have a very consistent internal structure. It would be
> easy to remove and clean.
> Phil suggests a cheap supply of ceramic packings though ...
> Have you checked the aquarium shops for ceramic rings used for pre
> filtration. I recently bought 2 litres for change from £10
> (£4.85/l). I suspect they would do the same job. They also come in
> hex or tube shapes. There are also similar rings for bio filtration that
> have an open surface area so would perhaps be more efficient, though
> could be a bugger to clean
> More about using plates (rather than packed columns ...
> Ken : The idea with a fractionating column is a temperature gradient
> (falling of course) as you go UP the column, but a constant temperature
> ACROSS the column at any height. As the diameter of the column
> increases, it gets harder to achieve the constant temperature at a given
> height if you continue to use a packing material -- hence the plates.
> Plates give you resistance to flow in an upwards direction, but very
> easy "spreading" horizontally.
> George : From what I have read, a general rule of thumb is; up to 4" you
> would be better off with scrubbers, anything bigger than 4" and scrubber
> will tend to channel, from 4" up to 8" you would do well with packing
> like pall rings and the like, from 10" and up you would do well to use
> plates. However I have seen plans for a 4" still with bubble cap plates
> and they claim to be the most efficient still made. Their claim not
> mine. To make the 10" bubble cap plate type still work you would need
> somewhere around a 10 hp boiler or around 350,000 btu input. It would
> also produce up to or around 30 gallon of ethanol per hou using a 10%
> wash. I have gleaned this information from a lot of different sources
> and complyed it myself, none of it is to be considered absolute. Their
> has been some writings about using some sort of perforated plate with
> the packing on the 6 to 8 inch stills to help even out the vapor flow.
> On spacing I read once, and do not remember where that the spacing
> should be double the diameter as a rule of thumb. But the heat input,
> the quanity output, and the wash percent all effect this so it is hard
> to say. Their is no set rule to follow. Perforated plates require a lot
> of drilling and the bubble caps are hard to construct. Anything over a 6
> to 8 inch would require quite the effort to bring up to speed. Unless
> you have a cheap source of heat, a motor of some type that runs
> constancely , the expense of bringing one of the bigger one up to steam
> would be very high.
> One other thing that effects the plate type stills is wheather or not
> you are going to filter out the solids in your wash. If you are not then
> your plates would have to be designed to be self cleaning. If you do
> then the solids need to be compressed to get as much alcohol recovered
> as possible.
> Gaw : Using the photos ... of a bubble type plate still in Holland I
> built a four inch eight plate still which seems to work quite well on
> top of a six gallon electric water heater with benefit of a thermostat
> which I added. To further the experiment of continuous distilling I
> added a thirty gallon pot with a connection three plates above the
> smaller unit and after the complete system reaches operating temps the
> unit seems to function quite well at 94-95 per cent. I used ss plates
> which I found in a salvage yard and soldered the bubblers into separate
> units which I then bolted together, believe it or not, with ss bolts and
> neoprene gaskets on each end of the four inch pieces.
> Hennie writes:
> I think the best solution for an ethanol distillation would be a packing
> of copper rings. These should not be too difficult to manufacture.
> Winding a copperwire on a thin rod with an electric drill and cutting
> the created spring to rings shouldn't be too difficult.
> The height of packing needed in order to do the same job as an ideal
> plate is called the HETP - Height Equivalent to a Theoretical Plate.
> Smaller HETP's are better than large ones, as it means that for a
> given column height (say 1m) you end up with more ideal plates, eg only
> 2 plates (87% purity) if the HETP= 0.5m, but 4 plates (92% purity) if
> HETP = 0.25 m. If you don't have an exact number of plates,
> that's still OK; you'll end up somewhere proportionally between
> the two.
> So an empty column, with no packing, ain't going to do a lot. Sure,
> you might get a little liquid running down the sides of it, but this has
> got nowhere near the same surface area as using packing.
> The HETP for a packing depends on its:
> * Size (smaller objects pack together better). The size also needs to
> be in proportion to the column diameter too * Voidage (need to allow
> room for the gas & liquid to flow around them, don't want to block
> the column off) * Surface area (eg how many square meters of surface
> you have per cubic meter of packing the more surface area, the
> more places for the liquid & vapour to mingle) * The amount of
> liquid & vapour flowing around it
> Typical HETPs for common packings are :
> Packing HETP Stainless Steel Wool Scrubbers 0.13 m Marbles (10mm
> diameter) 0.33 m 6mm Ceramic Raschig Rings 0.24 m 13mm Ceramic
> Raschig Rings 0.38 m
> Zoran suggests that in some cases marbles may be as effective as a 0.2m
> These HETPs change depending on how much liquid & vapour are flowing
> around them. This ratio can be described by the Reflux Ratio - the ratio
> of Liquid flowing down the column over the amount of distillate drawn
> off :
> R = L / D = (V-D) / D
> --- In email@example.com, "whiskeyman50" <whiskeyman50>
> I am a pot still man. Have been studying reflux/column stills and cant
> figure out what plates are. Is there packing between plates? Can plates
> be added to your column any time? What do plates look like?
Running 300 gallons is way over the limits of the hobby distilling on
this site. If your looking at commercial applications then contact one
of the commercial forums. We do not recommend making that much at once
nor do we allow selling the product without a licence.
Frankly for a smooth product, I recommend several distillations, not
just a single one for top grade vodka, along with even purification by
JB. aka Waldo.
--- In firstname.lastname@example.org, "whiskeyman50" <whiskeyman50@...>
>my hand at vodka. I guess I should get down to brass tacks. I would like
> Thanks for your reply. I have done whiskey for years and now am trying
to run somewhere around 300 gallons of strained wash with an alcohol
content of around +- 15%. For these amounts would plates or packing be
best for a high purity? Can I distill one time with enough height (
packing or plates ) or would it have to be distilled twice to achieve
vodka grade purity?
> I'm sure these questions sound stupid. I've run a pot still with 2thumpers for years. I'm still trying to get a grasp on this whole column