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  • Rob Macrobert
    Morning folks, I ve been looking at Riku s description of AFC, as well as some of the rigs on the forum, and I must admit to being completely baffled on a
    Message 1 of 9 , Nov 9, 2008
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      Morning folks, I've been looking at Riku's description of AFC, as well as some of the rigs on the forum, and I must admit to being completely baffled on a couple of points.
      If I am understanding the process correctly on a VM rig,
      -The feed tube fills with wash
      -As the feed tube heats up, the alcohol boils off and the vapors cycle in the column until the ABV hits ~40-45% where it can "fall" out the take off tube.

      But, how does the tube refill with fresh wash? It looks to me, that we have to wait for what remains in the tube to boil off before the fresh charge can enter, and that would give us what Harry and the other knowledgeable ones have been saying is a VERY BAD THING, surge boiling.
      Based on that, if the wash is preheated to 40-50C before introduction, would that smooth out the surges and be an improvement? Or is this the type of thing where you use an undesirable to prevent worse things from happening? Such as choking or overloading.

      Or is my understanding of the process completely wrong and I'm making it out to be more complicated than it needs to be?

      If someone could explain this one to me, it would be greatly appreciated.

      Robbie Mac










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    • abbababbaccc
      The mash doesn t boil away. When the boiling event starts at the bottom the pipe, the pipe will burp out mash to the top of the packing. This means that
      Message 2 of 9 , Nov 9, 2008
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        The mash doesn't boil away. When the boiling event starts at the
        bottom the pipe, the pipe will "burp" out mash to the top of the
        packing. This means that there will be some room left in the pipe and
        cold mash will flow in and the boiling ceases. It gets heated,
        another burp and the cycle continues. This will result a continuous
        feed of mash to the top of the packing as long as the temperature at
        the lower parts of the column is adequate. When the bottom of the
        column cools down the cycle will stop, which is a good thing as
        otherwise you'd be getting alcohol out from the boiler overflow. When
        the cycle stops the column bottom starts to warm again and on we go
        with burping :)

        You could experiment with preheating of course but it is not
        necessary for this setup and could actually alter this burping
        behaviour.

        If you have trouble understanding this burping thing get a piece of
        pipe with closed bottom, fill it with water and apply some heat to
        the bottom. When the boiling starts it will spill out a considerable
        amount of liquid.

        Cheers, Riku

        --- In Distillers@yahoogroups.com, "Rob Macrobert" <macrobert@...>
        wrote:
        >
        >
        > Morning folks, I've been looking at Riku's description of AFC, as
        well as some of the rigs on the forum, and I must admit to being
        completely baffled on a couple of points.
        > If I am understanding the process correctly on a VM rig,
        > -The feed tube fills with wash
        > -As the feed tube heats up, the alcohol boils off and the vapors
        cycle in the column until the ABV hits ~40-45% where it can "fall"
        out the take off tube.
        >
        > But, how does the tube refill with fresh wash? It looks to me, that
        we have to wait for what remains in the tube to boil off before the
        fresh charge can enter, and that would give us what Harry and the
        other knowledgeable ones have been saying is a VERY BAD THING, surge
        boiling.
        > Based on that, if the wash is preheated to 40-50C before
        introduction, would that smooth out the surges and be an improvement?
        Or is this the type of thing where you use an undesirable to prevent
        worse things from happening? Such as choking or overloading.
        >
        > Or is my understanding of the process completely wrong and I'm
        making it out to be more complicated than it needs to be?
        >
        > If someone could explain this one to me, it would be greatly
        appreciated.
        >
        > Robbie Mac
        >
        >
        >
        >
        >
        >
        >
        >
        >
        >
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        > Get a Free Account at www.mail.com
        >
      • Rob Macrobert
        Thanks Riku, it makes more sense now, As I haven t seen any recommended sizing for the feed pipe -vs- wattage supplied, I would have to think that the cycle
        Message 3 of 9 , Nov 9, 2008
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          Thanks Riku, it makes more sense now,

          As I haven't seen any recommended sizing for the feed pipe -vs- wattage supplied, I would have to think that the cycle between burps is a variable that might be improved on by preheating.
          Or would it be likely to result in overloading the packing with more liquid than could be dealt with, with out more heat applied, bringing us full circle?
          Any thoughts?

          I have an air cooled, VM continuous, stripping column operating now, without AFC, and stopping it from choking is a bit of a chore at times. So I am very interested in figuring out if AFC will give me the control I'm looking for, without sacrificing output.

          BTW, love your book, but there are a couple of areas that seem to be lacking some of the in depth background information that is in other areas, such as sizing for air cooling, and how AFC works. <GR>

          Cheers,
          Robbie Mac



          ----- Original Message -----
          From: abbababbaccc
          To: Distillers@yahoogroups.com
          Subject: [Distillers] Re: Auto Feed Control
          Date: Sun, 09 Nov 2008 16:12:22 -0000





          The mash doesn't boil away. When the boiling event starts at the
          bottom the pipe, the pipe will "burp" out mash to the top of the
          packing. This means that there will be some room left in the pipe and
          cold mash will flow in and the boiling ceases. It gets heated,
          another burp and the cycle continues. This will result a continuous
          feed of mash to the top of the packing as long as the temperature at
          the lower parts of the column is adequate. When the bottom of the
          column cools down the cycle will stop, which is a good thing as
          otherwise you'd be getting alcohol out from the boiler overflow. When
          the cycle stops the column bottom starts to warm again and on we go
          with burping :)

          You could experiment with preheating of course but it is not
          necessary for this setup and could actually alter this burping
          behaviour.

          If you have trouble understanding this burping thing get a piece of
          pipe with closed bottom, fill it with water and apply some heat to
          the bottom. When the boiling starts it will spill out a considerable
          amount of liquid.

          Cheers, Riku






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        • abbababbaccc
          AFC is not my invention and I haven t tried one yet so I didn t write about it either. However, the concept is tested by Nykter and it works very well. IIRC
          Message 4 of 9 , Nov 9, 2008
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            AFC is not my invention and I haven't tried one yet so I didn't write
            about it either. However, the concept is tested by Nykter and it
            works very well. IIRC nykter had 8mm or 10mm feed pipe and 1kW
            heating element in a 2" continuous stripper.

            Preheating should indeed work as long as it's not getting heated too
            close to boiling point. Once you are very close to boiling the
            boiling event may start in too large area and cause burping back to
            reservoir and slow down the refilling of the tube. Just a theory but
            I'd be cautious.

            Aircooling, for copper pipe you can calculate the ambient cooling
            based on values that match real life examples. For convector pipes
            that get's really complicated and when you start using fans the math
            is IMO too complicated to present real life with any accuracy. Thus I
            took few examples one could use for most common still sizes. Granted
            I could have used more examples but I didn't have that many of them
            available :(

            If you are worried about AFC you could always use a solenoid valve
            for feed control and apply the principles presented in E-ARC chapter
            for control. Only this time you want to keep the temperature at the
            bottom of the column at 100C.

            Cheers, Riku


            --- In Distillers@yahoogroups.com, "Rob Macrobert" <macrobert@...>
            wrote:
            >
            > Thanks Riku, it makes more sense now,
            >
            > As I haven't seen any recommended sizing for the feed pipe -vs-
            wattage supplied, I would have to think that the cycle between burps
            is a variable that might be improved on by preheating.
            > Or would it be likely to result in overloading the packing with
            more liquid than could be dealt with, with out more heat applied,
            bringing us full circle?
            > Any thoughts?
            >
            > I have an air cooled, VM continuous, stripping column operating
            now, without AFC, and stopping it from choking is a bit of a chore at
            times. So I am very interested in figuring out if AFC will give me
            the control I'm looking for, without sacrificing output.
            >
            > BTW, love your book, but there are a couple of areas that seem to
            be lacking some of the in depth background information that is in
            other areas, such as sizing for air cooling, and how AFC works. <GR>
            >
            > Cheers,
            > Robbie Mac
            >
            >
            >
            > ----- Original Message -----
            > From: abbababbaccc
            > To: Distillers@yahoogroups.com
            > Subject: [Distillers] Re: Auto Feed Control
            > Date: Sun, 09 Nov 2008 16:12:22 -0000
            >
            >
            >
            >
            >
            > The mash doesn't boil away. When the boiling event starts at the
            > bottom the pipe, the pipe will "burp" out mash to the top of the
            > packing. This means that there will be some room left in the pipe
            and
            > cold mash will flow in and the boiling ceases. It gets heated,
            > another burp and the cycle continues. This will result a continuous
            > feed of mash to the top of the packing as long as the temperature
            at
            > the lower parts of the column is adequate. When the bottom of the
            > column cools down the cycle will stop, which is a good thing as
            > otherwise you'd be getting alcohol out from the boiler overflow.
            When
            > the cycle stops the column bottom starts to warm again and on we go
            > with burping :)
            >
            > You could experiment with preheating of course but it is not
            > necessary for this setup and could actually alter this burping
            > behaviour.
            >
            > If you have trouble understanding this burping thing get a piece of
            > pipe with closed bottom, fill it with water and apply some heat to
            > the bottom. When the boiling starts it will spill out a
            considerable
            > amount of liquid.
            >
            > Cheers, Riku
            >
            >
            >
            >
            >
            >
            > --
            > Be Yourself @ mail.com!
            > Choose From 200+ Email Addresses
            > Get a Free Account at www.mail.com
            >
          • mavnkaf
            ... well as some of the rigs on the forum, and I must admit to being completely baffled on a couple of points. ... cycle in the column until the ABV hits
            Message 5 of 9 , Nov 9, 2008
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              --- In Distillers@yahoogroups.com, "Rob Macrobert" <macrobert@...>
              wrote:
              >
              >
              > Morning folks, I've been looking at Riku's description of AFC, as
              well as some of the rigs on the forum, and I must admit to being
              completely baffled on a couple of points.
              > If I am understanding the process correctly on a VM rig,
              > -The feed tube fills with wash
              > -As the feed tube heats up, the alcohol boils off and the vapors
              cycle in the column until the ABV hits ~40-45% where it can "fall"
              out the take off tube.
              >
              > But, how does the tube refill with fresh wash? It looks to me, that
              we have to wait for what remains in the tube to boil off before the
              fresh charge can enter, and that would give us what Harry and the
              other knowledgeable ones have been saying is a VERY BAD THING, surge
              boiling.
              > Based on that, if the wash is preheated to 40-50C before
              introduction, would that smooth out the surges and be an improvement?
              Or is this the type of thing where you use an undesirable to prevent
              worse things from happening? Such as choking or overloading.
              >
              > Or is my understanding of the process completely wrong and I'm
              making it out to be more complicated than it needs to be?
              >
              > If someone could explain this one to me, it would be greatly
              appreciated.
              >
              > Robbie Mac
              >
              ......................................................


              --- In Distillers@yahoogroups.com, "Rob Macrobert" <macrobert@...>
              wrote:
              >
              >
              > Morning folks, I've been looking at Riku's description of AFC, as
              well as some of the rigs on the forum, and I must admit to being
              completely baffled on a couple of points.
              > If I am understanding the process correctly on a VM rig,
              > -The feed tube fills with wash
              > -As the feed tube heats up, the alcohol boils off and the vapors
              cycle in the column until the ABV hits ~40-45% where it can "fall"
              out the take off tube.
              >
              > But, how does the tube refill with fresh wash? It looks to me, that
              we have to wait for what remains in the tube to boil off before the
              fresh charge can enter, and that would give us what Harry and the
              other knowledgeable ones have been saying is a VERY BAD THING, surge
              boiling.
              > Based on that, if the wash is preheated to 40-50C before
              introduction, would that smooth out the surges and be an improvement?
              Or is this the type of thing where you use an undesirable to prevent
              worse things from happening? Such as choking or overloading.
              >
              > Or is my understanding of the process completely wrong and I'm
              making it out to be more complicated than it needs to be?
              >
              > If someone could explain this one to me, it would be greatly
              appreciated.
              >
              Robbie Mac



              Hi Robbie,

              I made a AFC pot still a little while ago using Riku's advice, it
              worked first go with no real problems, it made a constant 50%
              distillate which is what I was aiming for. I used it as a stripping
              still for making rum.

              Preheating the wash will speed things up, but I have not tried it; my
              wash was at shed temp 25-30 C.

              Where you asked, "how does the tube refill with fresh wash?" The AFC
              external tube gets feed by the lower tank, as the heated wash "burps"
              or over flows into the copper packing new wash is introduced from the
              feeder tank, it's a continuous process. By using an inline valve you
              can control how fast (limited), or how slow you want the process to
              happen.

              I constantly checked the temp gauge at the bottom of the column to
              see if I'm going too fast, in my case, the optimum wash flow/
              distillate flow/bottom temp was 99.4 C but I can't remember the
              atmospheric pressure at the time but I was doing this @ 262 ft above
              sea level.

              To further answer the question about feeding the AFC tube, I used a
              two-tier tank setup, one tank higher than the other; the top tank
              feeds the lower tank via a float valve. That way the lower tank wash
              level remains constant thus pressure is constant, so the inline valve
              to control the wash flow rate would not change too much.

              My prototype AFC stripping still, using Riku's advice was not fast or
              really efficient but it did work how I thought it should or how I
              wanted it. When tested it I put 50 liters though it, which took
              about 8 hours from start up to finish, (I fiddle too much). It would
              have taken 5 hours if knew the optimum setting also I was using an
              1100 watt element too!!

              I know people would say I was not really stripping the wash, but on a
              test run I had to take it easy. Now I know how works I can see the
              time to strip a 50 liter wash down to 3 hours max, using a 2400 watt
              element. I hope my convoluted dribble helps. I think any words on
              the topic will help, as it will be recorded, right or wrong.

              Cheers
              Marc

              Btw sorry if have gone over what Riku had said or bad grammar and
              every thing else. Check the pictures out; they may explain what I
              was going on about. Look at the 5 pictures, if you need construction
              pic's let me know.

              http://tinyurl.com/555rkl
            • Rob Macrobert
              Thanks Riku, When I selected my convection tubes, I used the chart for a product called Slant Fin, which gave me 1Kw/m @ 180F vapor temp with a 20C ambient.
              Message 6 of 9 , Nov 10, 2008
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                Thanks Riku,
                When I selected my convection tubes, I used the chart for a product called Slant Fin, which gave me 1Kw/m @ 180F vapor temp with a 20C ambient.
                Considering I'm using a pair of 1.3 meter tubes on a 1Kw boiler @ 4-9C ambient, I'm good there.

                I'll give it a try with the preheat, as it's a cheap trial (thrift shop coffee maker) and see what happens if it doesn't work, it will be simple to remove.

                Cheers,



                ----- Original Message -----
                From: abbababbaccc
                To: Distillers@yahoogroups.com
                Subject: [Distillers] Re: Auto Feed Control
                Date: Mon, 10 Nov 2008 05:25:17 -0000





                AFC is not my invention and I haven't tried one yet so I didn't write
                about it either. However, the concept is tested by Nykter and it
                works very well. IIRC nykter had 8mm or 10mm feed pipe and 1kW
                heating element in a 2" continuous stripper.

                Preheating should indeed work as long as it's not getting heated too
                close to boiling point. Once you are very close to boiling the
                boiling event may start in too large area and cause burping back to
                reservoir and slow down the refilling of the tube. Just a theory but
                I'd be cautious.

                Aircooling, for copper pipe you can calculate the ambient cooling
                based on values that match real life examples. For convector pipes
                that get's really complicated and when you start using fans the math
                is IMO too complicated to present real life with any accuracy. Thus I
                took few examples one could use for most common still sizes. Granted
                I could have used more examples but I didn't have that many of them
                available :(

                If you are worried about AFC you could always use a solenoid valve
                for feed control and apply the principles presented in E-ARC chapter
                for control. Only this time you want to keep the temperature at the
                bottom of the column at 100C.

                Cheers, Riku



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                Get a Free Account at www.mail.com
              • Rob Macrobert
                Sounds good Marc, right now I m running a constant feed that does 30L in about 3-4 hours, but with the occasional choking issue leaving it alone even long
                Message 7 of 9 , Nov 10, 2008
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                  Sounds good Marc, right now I'm running a constant feed that does 30L in about 3-4 hours, but with the occasional choking issue leaving it alone even long enough to have a leak is not a good idea.
                  I'm going to give AFC a try with a preheated wash and see what happens.
                  BTW, what size feed tube and column are you running?
                  Cheers,


                  Robbie Mac
                  Sometime tinkerer and sometimes it even works....

                  ----- Original Message -----
                  From: mavnkaf
                  To: Distillers@yahoogroups.com
                  Subject: [Distillers] Re: Auto Feed Control
                  Date: Mon, 10 Nov 2008 07:31:06 -0000






                  Hi Robbie,

                  I made a AFC pot still a little while ago using Riku's advice, it
                  worked first go with no real problems, it made a constant 50%
                  distillate which is what I was aiming for. I used it as a stripping
                  still for making rum.

                  Preheating the wash will speed things up, but I have not tried it; my
                  wash was at shed temp 25-30 C.

                  Where you asked, "how does the tube refill with fresh wash?" The AFC
                  external tube gets feed by the lower tank, as the heated wash "burps"
                  or over flows into the copper packing new wash is introduced from the
                  feeder tank, it's a continuous process. By using an inline valve you
                  can control how fast (limited), or how slow you want the process to
                  happen.

                  I constantly checked the temp gauge at the bottom of the column to
                  see if I'm going too fast, in my case, the optimum wash flow/
                  distillate flow/bottom temp was 99.4 C but I can't remember the
                  atmospheric pressure at the time but I was doing this @ 262 ft above
                  sea level.

                  To further answer the question about feeding the AFC tube, I used a
                  two-tier tank setup, one tank higher than the other; the top tank
                  feeds the lower tank via a float valve. That way the lower tank wash
                  level remains constant thus pressure is constant, so the inline valve
                  to control the wash flow rate would not change too much.

                  My prototype AFC stripping still, using Riku's advice was not fast or
                  really efficient but it did work how I thought it should or how I
                  wanted it. When tested it I put 50 liters though it, which took
                  about 8 hours from start up to finish, (I fiddle too much). It would
                  have taken 5 hours if knew the optimum setting also I was using an
                  1100 watt element too!!

                  I know people would say I was not really stripping the wash, but on a
                  test run I had to take it easy. Now I know how works I can see the
                  time to strip a 50 liter wash down to 3 hours max, using a 2400 watt
                  element. I hope my convoluted dribble helps. I think any words on
                  the topic will help, as it will be recorded, right or wrong.

                  Cheers
                  Marc

                  Btw sorry if have gone over what Riku had said or bad grammar and
                  every thing else. Check the pictures out; they may explain what I
                  was going on about. Look at the 5 pictures, if you need construction
                  pic's let me know.

                  http://tinyurl.com/555rkl


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                  Choose From 200+ Email Addresses
                  Get a Free Account at www.mail.com
                • mavnkaf
                  ... 30L in about 3-4 hours, but with the occasional choking issue leaving it alone even long enough to have a leak is not a good idea. ... happens. ... Ruki
                  Message 8 of 9 , Nov 10, 2008
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                    --- In Distillers@yahoogroups.com, "Rob Macrobert" <macrobert@...>
                    wrote:
                    >
                    > Sounds good Marc, right now I'm running a constant feed that does
                    30L in about 3-4 hours, but with the occasional choking issue leaving
                    it alone even long enough to have a leak is not a good idea.
                    > I'm going to give AFC a try with a preheated wash and see what
                    happens.
                    > BTW, what size feed tube and column are you running?
                    > Cheers,
                    >
                    >

                    Ruki suggested 8 mm or 10 mm, I went with the 8 mm feed tube with no
                    problems, the column is 50 mm x 110 cm, fully packed with copper
                    mesh. As you saw in my pictures I used a 20 litre coffee urn which
                    really lent it self to the job.

                    Cheers
                    Marc

                    btw, I'll add some construction pics later
                  • mavnkaf
                    Ooppps, sorry Riku, I just mispelt your name. Cheers Marc
                    Message 9 of 9 , Nov 10, 2008
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                      Ooppps, sorry Riku, I just mispelt your name.

                      Cheers
                      Marc

                      > Ruki suggested 8 mm or 10 mm, I went with the 8 mm feed tube with no
                      > problems
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