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MicroHydro question

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  • Bob Boyce
    I currently have a small (1.2 KW) PV solar array, and I am wanting to add a homebrew microhydroelectric installation on my property. For a test, I laid about
    Message 1 of 8 , Aug 2, 2004
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      I currently have a small (1.2 KW) PV solar array, and I am wanting to
      add a homebrew microhydroelectric installation on my property.

      For a test, I laid about 80 feet of 2" PVC pipe in the creekbed with
      a small rock dam at the head to collect water, and at the end I have
      a 90 ell with a couple of feet of pipe sticking straight up to give a
      bit of back pressure. I need to figure out how to deal with the
      problem of leaves and twigs and such from plugging up the inlet. If
      the weather is nice, it lasts a long time between cleanouts, but any
      strong wind or hard rain and it plugs up rather quickly. During the
      fall it was getting plugged up almost daily. I tried making a large
      coarse screen bubble out of lathe mesh to filter the larger stuff
      while allowing the smaller particles to pass, since they do not plug
      the pipe, but the screen gets all plastered with leaves and blocks
      the flow. I was hoping that the flow of the creek past this inlet
      screen would keep it washed clear, but the pipe suction is so strong
      that it does not work that way. Does anyone have any suggestions on
      how to solve this issue. I have not decided yet which is the best
      homebrew approach to take in order to extract energy from this moving
      water. I do not have a lot of head to work with so it will have to be
      something that can work with lower pressure, and won't cost a lot to
      build.


      Bob
    • Beeuwkes
      RE.. ... Bob, I read, was it here?, that for small applications you can put a perforated inlet pipe in a slightly dug out streambed and cover it with crushed
      Message 2 of 8 , Aug 3, 2004
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        RE..
        > I currently have a small (1.2 KW) PV solar array, and I am wanting to
        > add a homebrew microhydroelectric installation on my property.


        Bob, I read, was it here?, that for small applications you can put a
        perforated inlet pipe in a slightly dug out streambed and cover it with
        crushed stone... thus making a natural sort of screen. If the current was
        sufficient it might keep leaves etc. from settling (and therefore sealing
        the floor of the streambed.
        \Chris
      • Frank Leslie
        Perhaps a smoother screen mounted at ~5 to 10 degrees to the flow so that the water goes through sideways into a collector box while the flow rushing past
        Message 3 of 8 , Aug 3, 2004
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          Perhaps a smoother screen mounted at ~5 to 10 degrees to the flow so that
          the water goes through sideways into a collector box while the flow rushing
          past cleans the surface of the screen. I'm thinking of parallel rods like
          refrigerator shelf but 1/4 inch apart.

          Frank Leslie
          -----Original Message-----
          From: Bob Boyce [mailto:theghost@...]
          Sent: Tuesday, August 03, 2004 2:12 AM
          To: microhydro@yahoogroups.com
          Subject: [microhydro] MicroHydro question


          I currently have a small (1.2 KW) PV solar array, and I am wanting to
          add a homebrew microhydroelectric installation on my property.

          For a test, I laid about 80 feet of 2" PVC pipe in the creekbed with
          a small rock dam at the head to collect water, and at the end I have
          a 90 ell with a couple of feet of pipe sticking straight up to give a
          bit of back pressure. I need to figure out how to deal with the
          problem of leaves and twigs and such from plugging up the inlet. If
          the weather is nice, it lasts a long time between cleanouts, but any
          strong wind or hard rain and it plugs up rather quickly. During the
          fall it was getting plugged up almost daily. I tried making a large
          coarse screen bubble out of lathe mesh to filter the larger stuff
          while allowing the smaller particles to pass, since they do not plug
          the pipe, but the screen gets all plastered with leaves and blocks
          the flow. I was hoping that the flow of the creek past this inlet
          screen would keep it washed clear, but the pipe suction is so strong
          that it does not work that way. Does anyone have any suggestions on
          how to solve this issue. I have not decided yet which is the best
          homebrew approach to take in order to extract energy from this moving
          water. I do not have a lot of head to work with so it will have to be
          something that can work with lower pressure, and won't cost a lot to
          build.


          Bob






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        • Nando
          BOB: The setting of a pipe to reduce the sucking of debris into the pipe calls for setting the pipe well below the water level and the dispersion of the water
          Message 4 of 8 , Aug 3, 2004
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            BOB:

            The setting of a pipe to reduce the sucking of debris into the pipe calls
            for setting the pipe well below the water level and the dispersion of the
            water suction effects.

            Some of the solutions:
            making a large pond to keep the floating debris floating and not getting
            close to the inlet
            A slanted semi fine mesh wall feeding the pond, additional wall needs to
            direct the water in an angle away from the mesh wall to generate eddy
            currents to wash the debris from the mesh wall -- this unhappily depends on
            the terrain, the creek water level and depth of the water and each place
            needs careful observation to determine the best arrangement of the intake
            parts.

            The pipe intake should be expanded, we have increased the intake 20 to 100
            times the pipe diameter area to reduce the sucking effects to a minimum.

            Mesh containers around the intake to stop small debris from entering the
            pipe, We have made the last mesh not larger than 1/3 of a Turbine Nozzle
            diameter to avoid clogging.

            We have installed more than one debris mesh wall, sometimes in a scaled
            diameter size for progressive debris size control.( 2 or 3 ) debris walls.

            Intake installation is not the last thing to do, it should be planned as one
            of the most important factors for a successful and long life hydro system.

            Debris mesh walls do not mean a wall but an arrangement of walls,
            containers, enclosures around the intake pipe.

            Weavers sense the escaping water currents in their ponds and run to clog
            those escape sites, so the water current into the pipe needs to be diffused
            in a much larger area before entering into the pipe for the weaver not to
            detect it, in some places the intake area needs to be incremented many times
            over and/or somewhat large mesh containers around the piping to keep the
            Weaver away from sending the "escaping water" and "drain holes".

            Regards

            Nando

            ----- Original Message -----
            From: "Bob Boyce" <theghost@...>
            To: <microhydro@yahoogroups.com>
            Sent: Tuesday, August 03, 2004 1:12 AM
            Subject: [microhydro] MicroHydro question


            > I currently have a small (1.2 KW) PV solar array, and I am wanting to
            > add a homebrew microhydroelectric installation on my property.
            >
            > For a test, I laid about 80 feet of 2" PVC pipe in the creekbed with
            > a small rock dam at the head to collect water, and at the end I have
            > a 90 ell with a couple of feet of pipe sticking straight up to give a
            > bit of back pressure. I need to figure out how to deal with the
            > problem of leaves and twigs and such from plugging up the inlet. If
            > the weather is nice, it lasts a long time between cleanouts, but any
            > strong wind or hard rain and it plugs up rather quickly. During the
            > fall it was getting plugged up almost daily. I tried making a large
            > coarse screen bubble out of lathe mesh to filter the larger stuff
            > while allowing the smaller particles to pass, since they do not plug
            > the pipe, but the screen gets all plastered with leaves and blocks
            > the flow. I was hoping that the flow of the creek past this inlet
            > screen would keep it washed clear, but the pipe suction is so strong
            > that it does not work that way. Does anyone have any suggestions on
            > how to solve this issue. I have not decided yet which is the best
            > homebrew approach to take in order to extract energy from this moving
            > water. I do not have a lot of head to work with so it will have to be
            > something that can work with lower pressure, and won't cost a lot to
            > build.
            >
            >
            > Bob
            >
            >
            >
            >
            >
            >
            >
            > Does your company feature in the microhydro business directory at
            http://microhydropower.net/directory ? If not, please register free of
            charge and be exposed to the microhydro community world wide!
            >
            > NOTE: The advertisements in this email are added by Yahoogroups who
            provides us with free email group services. The microhydro-group does not
            endorse products or support the advertisements in any way.
            >
            > More information on micro hydropower at http://microhydropower.net
            >
            > To unsubscribe: send empty message to
            microhydro-unsubscribe@...
            > Yahoo! Groups Links
            >
            >
            >
            >
            >
          • rkweir@aol.com
            Bob Please visit my web site _www.hydroscreen.com_ (http://www.hydroscreen.com) On the site I have a number of pictures of diversions for Hydro utilizing
            Message 5 of 8 , Aug 3, 2004
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              Bob

              Please visit my web site _www.hydroscreen.com_ (http://www.hydroscreen.com)
              On the site I have a number of pictures of diversions for Hydro utilizing
              Coanda effect wedge wire screens. The screens are for all practical purposes
              are self cleaning and will remove 90% of everything 50% of the slot opening.
              I usually recommend a .5mm (.019 in) slot opening. If you would like, I
              would be happy to assist in figuring out a diversion scheme that will work for
              your particular diversion site. One of the most important considerations when
              you are setting up a small Hydro is the design of your intake. Many a good
              Hydro unit has been shut down because of a poor diversion.

              Sincerely,

              Bob

              Robert K. Weir P.E.
              303-333-6071



              [Non-text portions of this message have been removed]
            • Dan
              ... to ... with ... have ... give a ... If ... any ... the ... large ... plug ... strong ... on ... moving ... be ... to ... Bob, This is why they use a
              Message 6 of 8 , Aug 3, 2004
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                --- In microhydro@yahoogroups.com, "Bob Boyce" <theghost@r...> wrote:
                > I currently have a small (1.2 KW) PV solar array, and I am wanting
                to
                > add a homebrew microhydroelectric installation on my property.
                >
                > For a test, I laid about 80 feet of 2" PVC pipe in the creekbed
                with
                > a small rock dam at the head to collect water, and at the end I
                have
                > a 90 ell with a couple of feet of pipe sticking straight up to
                give a
                > bit of back pressure. I need to figure out how to deal with the
                > problem of leaves and twigs and such from plugging up the inlet.
                If
                > the weather is nice, it lasts a long time between cleanouts, but
                any
                > strong wind or hard rain and it plugs up rather quickly. During
                the
                > fall it was getting plugged up almost daily. I tried making a
                large
                > coarse screen bubble out of lathe mesh to filter the larger stuff
                > while allowing the smaller particles to pass, since they do not
                plug
                > the pipe, but the screen gets all plastered with leaves and blocks
                > the flow. I was hoping that the flow of the creek past this inlet
                > screen would keep it washed clear, but the pipe suction is so
                strong
                > that it does not work that way. Does anyone have any suggestions
                on
                > how to solve this issue. I have not decided yet which is the best
                > homebrew approach to take in order to extract energy from this
                moving
                > water. I do not have a lot of head to work with so it will have to
                be
                > something that can work with lower pressure, and won't cost a lot
                to
                > build.
                >
                >
                > Bob

                Bob, This is why they use a penstock(A kind of settling pond)on
                larger hydroplants.
                In your case I would recommend you build a small enclosure with a
                volume at least large enough to let small stuff that passes through
                the screen and an opening, say 5-10 times the size of your pipe,
                nearly perpendicular to your stream flow and screen that. The flow
                should keep the screen cleared off.
                Putting a cover over the top to prevent debris from falling might
                be a good idea as well.
                Dan
              • Joe Cole
                I d use a tapered approach (1:20 or so) between your pipe and a trash rack to reduce the velocity of the water through the rack. I say a trash rack for two
                Message 7 of 8 , Aug 4, 2004
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                  I'd use a tapered approach (1:20 or so) between your pipe and
                  a "trash rack" to reduce the velocity of the water through
                  the rack.
                  I say a "trash rack" for two reasons. I trash rack is the
                  correct
                  terminology and it the right application for what you want to do.
                  Screens tend to plug naturally because of their elements
                  perpendicular to stream flow. Track racks are pretty much self-
                  cleaning if designed properly. For your application the rack needs
                  to be in a fast section of the stream and be perpendicular (not about
                  90 deg to stream flow but absolutely 90 deg to the stream flow. If
                  less then 90 deg water flowing into the rack tends to try and force
                  debris into the grating while more then 90 deg eddy's are
                  produced
                  which will tend to keep debris in circulation on the face of the
                  grating. If the grate is at 90 deg to stream flow then the streams
                  own water tends to wash debris off the grate. The grating should be
                  flat steel stock (3/16 x 1 inch stripe) spaced approx half of your
                  nozzle openings (impulse wheel) of half your blade spacing (reaction
                  turbine). Frank said, "I'm thinking of parallel rods like
                  refrigerator shelf" That's a pretty good description of what
                  it
                  should look like. The grating (strips) must be parallel with stream
                  flow and maybe have only one vertical support (for mechanical
                  stability) on the backside of the grate. For your application I'm
                  thinking about a grate surface of 8 x 14 inches or so.

                  Regards,

                  Joe
                • Bob Boyce
                  Thank you all for your speedy replies. I now have a lot of options to explore. Bob
                  Message 8 of 8 , Aug 4, 2004
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                    Thank you all for your speedy replies. I now have a lot of options to
                    explore.

                    Bob
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