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Re: [microhydro] Siphoned hydro scheme

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  • Martin.Leahy
    Gerard The siphon height is limited by atmospheric pressure (it is the weight of the atmosphere which will push the water into the vacuum created by the water
    Message 1 of 5 , Sep 30 10:58 PM
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      Gerard

      The siphon height is limited by atmospheric pressure (it is the weight of the atmosphere which will push the water into the vacuum created by the water pulling down the other side) - in normal circumstances max. 10 m. Also this siphon height is not usable as the water coming down balances the water being pulled up, so the net head is still from the top of the water in the tank to the exit level.

      We would need some more information to answer your question.

      1. Is 85 m the net head as defined above? I guess it is because you use the shorthand OD which I presume means Ordnance Datum. I'm not sure that's familiar to people outside Ireland/Britain.
      2. Is the forebay necessary as part of the water treatment?
      3. What is the height difference between th water exit and the peak of the lowest route possible?
      4. Is a lower route much longer (high penstock cost) or just not possible?

      If the forebay is not necessary and a route (burried) can be found which has a peak less than 10 m, then avoiding pumps and turbines altogether is the most efficient route.

      Regards,
      Martin

      ---------------------------

      ----- Original Message -----
      From: microhydro@yahoogroups.com <microhydro@yahoogroups.com>
      To: microhydro@yahoogroups.com <microhydro@yahoogroups.com>
      Sent: Tue Sep 30 10:03:32 2008
      Subject: [microhydro] Siphoned hydro scheme


      Dear Group Members,

      I am investigating an unusual SHP scheme in the UK and would greatly appreciate your thoughts. The hydropower plant will form part of a wastewater treatment system. For environmental reasons, water leaving the treatment plant has to be redirected into a river 6km away and it is proposed that a hydro scheme is incorporated into the system. The initial proposal is as follows:
      1. Clean water will exit the treatment plant (5m OD) and will be pumped 3km up to a hill crest (90m OD);
      2. At the hillcrest a forebay tank will temporarily store the water before it is released down the other side of the hill via another 3km penstock;
      3. A turbine (Turgo) located at the foot of the hill (also 5m OD) will convert the kinetic energy into electrical and be exported to the grid.
      4. The water will enter the river via an open channel;
      5. Approximately 0.231 m3/s is the firm flow.

      In this configuration, the hydro scheme will produce less electricity than the pumps consume, but the developers must install the penstocks and redirect the water anyway, so it is more of an energy efficiency measure. However, I am considering to siphon the water from the treatment plant up the hill and down into the turbine.

      Is this a feasible method, or is the height (85m head) and distances (6km overall) too large?
      A penstock of 500mm diameter is being considered, would a smaller diameter be required for siphoning?
      Will a reaction turbine (Francis) be required to ensure a closed system? i.e. submerged draft tube.

      I apologise for the long mail, and I hope that you may be able to answer my questions directly or point to a useful source (book, journal, etc.)

      Kind Regards,

      GB Fitzgerald

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    • BjornOlaf
      From what I remember from my physics classes many years back.....a siphon can maximum work up the height of 9.8m....so I think your 85m will be impossible to
      Message 2 of 5 , Oct 1, 2008
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        From what I remember from my physics classes many years back.....a siphon can maximum work up the height of 9.8m....so I think your 85m will be impossible to attain without an active pump.
        As a summer job once I worked for a hydro generator company in Norway and designed a system whereby water was pumped up a very high mountain to a lake for later use to even a flow in a river for environmental reasons. I think the overall efficiency of re-genrating electricity from this concept was in the high 80's %. Thus I think your idea of regenerating at the other end sounds viable given the loss in the piping distance/diameter doesent reduce the overall efficiency to much.
        /Bjorn

        --- On Tue, 9/30/08, Gerard Brendan Fitzgerald <gerard.brendan.fitzgerald@...> wrote:

        From: Gerard Brendan Fitzgerald <gerard.brendan.fitzgerald@...>
        Subject: [microhydro] Siphoned hydro scheme
        To: microhydro@yahoogroups.com
        Date: Tuesday, September 30, 2008, 10:03 AM







        Dear Group Members,

        I am investigating an unusual SHP scheme in the UK and would greatly appreciate your thoughts. The hydropower plant will form part of a wastewater treatment system. For environmental reasons, water leaving the treatment plant has to be redirected into a river 6km away and it is proposed that a hydro scheme is incorporated into the system. The initial proposal is as follows:
        1. Clean water will exit the treatment plant (5m OD) and will be pumped 3km up to a hill crest (90m OD);
        2. At the hillcrest a forebay tank will temporarily store the water before it is released down the other side of the hill via another 3km penstock;
        3. A turbine (Turgo) located at the foot of the hill (also 5m OD) will convert the kinetic energy into electrical and be exported to the grid.
        4. The water will enter the river via an open channel;
        5. Approximately 0.231 m3/s is the firm flow.

        In this configuration, the hydro scheme will produce less electricity than the pumps consume, but the developers must install the penstocks and redirect the water anyway, so it is more of an energy efficiency measure. However, I am considering to siphon the water from the treatment plant up the hill and down into the turbine.

        Is this a feasible method, or is the height (85m head) and distances (6km overall) too large?
        A penstock of 500mm diameter is being considered, would a smaller diameter be required for siphoning?
        Will a reaction turbine (Francis) be required to ensure a closed system? i.e. submerged draft tube.

        I apologise for the long mail, and I hope that you may be able to answer my questions directly or point to a useful source (book, journal, etc.)

        Kind Regards,

        GB Fitzgerald

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      • ian benson
        The water in a siphon is supported by atmospheric pressure. This means you can never siphon water up a vertical distance of more than 10m - in theory. And, in
        Message 3 of 5 , Oct 1, 2008
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          The water in a siphon is supported by atmospheric pressure. This means you
          can never siphon water up a vertical distance of more than 10m - in theory.
          And, in practice only a few vertical metres will work (dissolved oxygen
          comes out of the water at reduced presure, collects at the high point and
          breaks the siphon).

          But the proposal you describe is not completely new: I have heard of similar
          systems in the oil industry to recover some pumping energy when pipelines
          are forced to go up and down again like this.

          Ian.

          On Tue, Sep 30, 2008 at 10:03 AM, Gerard Brendan Fitzgerald <
          gerard.brendan.fitzgerald@...> wrote:

          >
          > Dear Group Members,
          >
          > I am investigating an unusual SHP scheme in the UK and would greatly
          > appreciate your thoughts. The hydropower plant will form part of a
          > wastewater treatment system. For environmental reasons, water leaving the
          > treatment plant has to be redirected into a river 6km away and it is
          > proposed that a hydro scheme is incorporated into the system. The initial
          > proposal is as follows:
          > 1. Clean water will exit the treatment plant (5m OD) and will be pumped 3km
          > up to a hill crest (90m OD);
          > 2. At the hillcrest a forebay tank will temporarily store the water before
          > it is released down the other side of the hill via another 3km penstock;
          > 3. A turbine (Turgo) located at the foot of the hill (also 5m OD) will
          > convert the kinetic energy into electrical and be exported to the grid.
          > 4. The water will enter the river via an open channel;
          > 5. Approximately 0.231 m3/s is the firm flow.
          >
          > In this configuration, the hydro scheme will produce less electricity than
          > the pumps consume, but the developers must install the penstocks and
          > redirect the water anyway, so it is more of an energy efficiency measure.
          > However, I am considering to siphon the water from the treatment plant up
          > the hill and down into the turbine.
          >
          > Is this a feasible method, or is the height (85m head) and distances (6km
          > overall) too large?
          > A penstock of 500mm diameter is being considered, would a smaller diameter
          > be required for siphoning?
          > Will a reaction turbine (Francis) be required to ensure a closed system?
          > i.e. submerged draft tube.
          >
          > I apologise for the long mail, and I hope that you may be able to answer my
          > questions directly or point to a useful source (book, journal, etc.)
          >
          > Kind Regards,
          >
          > GB Fitzgerald
          >
          > ----------------------------------------------------------
          > Ta an r-phost seo fe reir an tseanta / na seanta seo leanas ata le fail ag
          > This e-mail is subject to the following disclaimer(s) available at
          >
          > http://www.ittralee.ie/EmailDisclaimer.html
          >
          > Smaoinigh ar an dtimpeallacht sula bpriontaileann tu an r-phost seo
          > Please consider the environment before printing this e-mail
          > ----------------------------------------------------------
          >
          > [Non-text portions of this message have been removed]
          >
          >
          >


          [Non-text portions of this message have been removed]
        • Gerard Brendan Fitzgerald
          Dear Members, Thank you for all your help, the information provided has been conclusive. Martin Leahy was looking for some further information regarding the
          Message 4 of 5 , Oct 3, 2008
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            Dear Members,

            Thank you for all your help, the information provided has been conclusive.

            Martin Leahy was looking for some further information regarding the scheme and it is as follows:
            1. Yes, 85m is the net head;
            2. Forebay is not necessary as part of water treatment, and water entering the tank is very clean with little or no suspended solids. It is more of a break-pressure tank than a conventional forebay.
            3 & 4. This is the only route open to us. Conveying water 'around' the hill is not an option in this case unfortunately. Therefore, net head is 85m.

            Thank you again folks for your prompt replies.

            Regards,
            GB Fitzgerald







            Gerard



            The siphon height is limited by atmospheric pressure (it is the weight of the atmosphere which will push the water into the vacuum created by the water pulling down the other side) - in normal circumstances max. 10 m. Also this siphon height is not usable as the water coming down balances the water being pulled up, so the net head is still from the top of the water in the tank to the exit level.



            We would need some more information to answer your question.



            1. Is 85 m the net head as defined above? I guess it is because you use the shorthand OD which I presume means Ordnance Datum. I'm not sure that's familiar to people outside Ireland/Britain.

            2. Is the forebay necessary as part of the water treatment?

            3. What is the height difference between th water exit and the peak of the lowest route possible?

            4. Is a lower route much longer (high penstock cost) or just not possible?



            If the forebay is not necessary and a route (burried) can be found which has a peak less than 10 m, then avoiding pumps and turbines altogether is the most efficient route.



            Regards,

            Martin



            ---------------------------



            ----- Original Message -----

            From: microhydro@yahoogroups.com <microhydro@yahoogroups.com>

            To: microhydro@yahoogroups.com <microhydro@yahoogroups.com>

            Sent: Tue Sep 30 10:03:32 2008

            Subject: [microhydro] Siphoned hydro scheme



            Dear Group Members,



            I am investigating an unusual SHP scheme in the UK and would greatly appreciate your thoughts. The hydropower plant will form part of a wastewater treatment system. For environmental reasons, water leaving the treatment plant has to be redirected into a river 6km away and it is proposed that a hydro scheme is incorporated into the system. The initial proposal is as follows:

            1. Clean water will exit the treatment plant (5m OD) and will be pumped 3km up to a hill crest (90m OD);

            2. At the hillcrest a forebay tank will temporarily store the water before it is released down the other side of the hill via another 3km penstock;

            3. A turbine (Turgo) located at the foot of the hill (also 5m OD) will convert the kinetic energy into electrical and be exported to the grid.

            4. The water will enter the river via an open channel;

            5. Approximately 0.231 m3/s is the firm flow.



            In this configuration, the hydro scheme will produce less electricity than the pumps consume, but the developers must install the penstocks and redirect the water anyway, so it is more of an energy efficiency measure. However, I am considering to siphon the water from the treatment plant up the hill and down into the turbine.



            Is this a feasible method, or is the height (85m head) and distances (6km overall) too large?

            A penstock of 500mm diameter is being considered, would a smaller diameter be required for siphoning?

            Will a reaction turbine (Francis) be required to ensure a closed system? i.e. submerged draft tube.



            I apologise for the long mail, and I hope that you may be able to answer my questions directly or point to a useful source (book, journal, etc.)



            Kind Regards,



            GB Fitzgerald



            ----------------------------------------------------------

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            This e-mail is subject to the following disclaimer(s) available at



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            Smaoinigh ar an dtimpeallacht sula bpriontaileann tu an r-phost seo

            Please consider the environment before printing this e-mail

            ----------------------------------------------------------



            [Non-text portions of this message have been removed]



            ------------------------------------



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            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@...! Groups Links



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