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28646Re: can some one explain

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  • Harry
    Apr 29, 2008
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      Two reasons you didn't get any answers.

      1.  Unless you have some understanding of Chemical Engineering processes, you'll find it difficult to follow continuous distillation theory and operation.

      2.  It's very difficult for we readers to follow what you want, because of your disjointed style of posting.  I don't mean to sound like I'm criticizing but... in order to communicate thoughts in writing for others to understand, you need to get the terminology right, so we are talking about the same things.  Otherwise communication breaks down and people just pass on by.

      Having said all that negative stuff (sorry), I'll try to help if I can.  But I will snip out some of the noise where necessary for clarity.  My comments are in blue text and corrections to your writings are in strikeout followed by red correction.  So here goes...


      --- In new_distillers@yahoogroups.com, "Jesse" <carolinacrisp@...> wrote:

      Anyways, the 2nd question in line is the main one,   see below
      > >
      > >
      > > hey I am going to leave a link below as a mater of fact so I don;t
      > > forget here it is now,
      > > http://ph.groups.yahoo.com/group/Distillers/photos/view/7bf9?b=5

      > > Anyways on this link you will see a Continuous still, All I want to
      > know
      > > is two things,
      > >
      > > 1: when you first start do you will fill the heating pot that is connected
      > > with column with wash or water, Seems wash would be better, Huh,

      Harrysays:  The heating pot you speak of is called a Reboiler, because it reboils the spent wash (now mostly water) that has already been boiled AND STRIPPED OF ITS ALCOHOL in the column.  The stripped wash drops into the bottom of the column and its attached reboiler.  The reboiler provides the rising steam to run the column and do the stripping.  That's the simple explanation of how continuous columns operate.

      But your observation above is correct.  When you first start up the continuous column the reboiler is filled by the incoming wash feed.  Then the feed is shut off and the reboiler fired up to make steam.  Then the wash feed is started again and adjusted with a valve (not shown in your example pic) to provide just enough feed to operate the column in balance without flooding the column (tricky operation, but do-able).

      > >
      > > 2: Ok this one I will descibe. The wash that comes from the reserve up
      > > top,. goes through a condencer Heat Exchanger at the bottom before going back up to
      > > half way up column, this I understand, What I don;t understand in the
      > > drawing, is what feeds that condencer

      Harry says:  The heat exchanger's job is to recover (recycle) some process heat.  In this configuration it is called a Pre-heater.  It uses the hot waste water from the reboiler to pre-heat the wash before being fed to the column for stripping.

       Also That Line
      > > that feeds the condencer. It looks like it just stops. It almost
      > > resembles a T. is the top of this line open,

      Harry says:  Yes it is open to atmosphere.  This prevents siphoning which would empty out the reboiler water and kill the whole operation.  (think siphoning gasoline out of your tank.  Same thing)



       I haven't found any detailed plans, unless I buy them,
      > > if you have some please send link,,, thanks for any information,,

      Harry says:  The best link I can provide to explain continuous distillation is Ming Tham's site here...
      ...but I warn you, even though it's a pretty straightforward site, you'll find it hard going if you don't understand basic Chem. Eng. as I said at the start of this post.  But cheer up.  Once you learn the correct terminology for the various parts & processes, it gets a lot easier.  :)

      > After thinking about it, Is this piece Like away a way to keep the level of
      > the wash right

      Harry says:  Yes

      , and it won't let steam out because its under the wash
      > line,

      Harry says:  Yes

      also should the end of it that is under the wash, be pointed
      > upwards so that steam doesn't make it in,

      Harry says:  No, not necessary.

      Also does it have a check
      > valve on the end exposed to air,

      Harry says:  No, it's open to atmosphere (watch this tube opening for blockages by insects that build mud nests when the column is not being used.)

      Probably not just long enough not to
      > let fluid out, 

      Harry says:  See above.

      > Also How or do you adjust the flow of wash in from the
      > resovior wash reservoir to allow the flow to dump over through the line I speak of pre-heater feedline, into the condencer Heat Exchanger that preheats, 

      Harry says:  See above where I mentioned the wash feed valve that is not shown in your example pic.

         I mean How do you make sure that it
      > is the left overs and not Good wash, 

      Harry says:  You will lose a tiny bit of wash at startup, but after that the pre-heater will always be fed with hot waste water (see above where I mentioned column operation).

      > does it need to be close to the bottom of pot,

      Harry says:  Yes, to keep the lower column and reboiler sealed from atmosphere.  In practice, all continuous columns operate under partial pressure.
      > Is there a lower level of ABV at the bottom when boiling, or Is it the
      > same no mater where it is in the pot,

      Harry says:  Without getting very technical and confusing you, consider it to be the same.

      meaning it does not separate like
      > oil and water,, (I know its not like oil and water that was the only
      > thing I could think of to compare with,,)    Ok thanks I again,, Hope
      > someone can answer these questions, I have read up on this subject, but
      > It seems that all the details that I need are not there,  The only stuff
      > that I can find will either be the facts or, the crummy drawing like I
      > have the link to.,. Theses are worthless if you don't have the knowledge
      > already,, don't see why I was sent to read on this stuff, when there is
      > really nothing to see, After reading The wiki definations that was the
      > end of it, And even they just give the facts, No place to ask or aquire
      > new info,,,
      >   so if any of you guys can find the time I will be so Greatfull,  Thanks
      > again,                              Uncle Jess,,
      > (heres try Number Duex)LOL
      > >
      > > This is what I want to do with the 6 inch pipe I belive, Something to
      > > this effect,, thanks again,
      > >
      > > Uncle Jess
      > >

      Harry says:  Jesse, you've got a long way to go before you start messing with continuous columns of this diameter.  I believe you said before that your pipe is 6in x 4ft.  That won't do for the whole column.  It may be enough for the stripper section (below the wash feed) but you'll need at least another 8 to 10 feet above that for the rectifying section.  The column diameter and column height are relative and worked out by very complicated mathematical formulae.  Columns are designed around a desired production rate, properly balanced for capacity & efficiency, not just slapped together and "see what we get".

      I hope this has answered your questions, but I fear it has probably raised a lot more.  I'm sorry but I cannot give you a crash course in Chem. Eng.  That takes years of Uni work to get your head around it.  So if you want to go ahead with it, I suggest you contact the relevant learning providers to see what they require from you and what they can do for you.

      regards Harry

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