RE: [microhydro] microhydro installation
- In thinking about your E-mail, I am coming to the conclusion I made a mistake in understanding your question. I understood that your funding agency is requiring you to install a "used" crossflow turbine and not a new turbine. What I think you might have meant was that the funding agency (which is most likely tied to the crossflow manufacturers), is requiring you to install a crossflow turbine as a condition for the funding. This makes my recommendation for a non crossflow turbine invalid. However, from an economic standpoint, I estimate a new crossflow to cost $45,000 to $60,000 each, and maybe more. A used vertical turbine with one stage costs $25,000 or less. This saves $100,000 in turbine cost and provides 1/3 more power to the grid than your two 20kw crossflows. In addition, the vertical turbine would require only one set of controls, have a much small footprint requiring a much small powerhouse and possibly could be located closer to the source which would reduce the length of the penstock. All these possibilities reduce the cost further. A crossflow seems to make sense only if the funding is 100%.I'm sorry for my original misunderstanding.
Date: Tue, 26 Mar 2013 14:00:11 +0800
Subject: [microhydro] microhydro installationHi everyone,I have one microhydro site which i would like everyone to comment.Parameters are:1) Flow (Q) = 2 m3/second2) Net head = 4.3 meters3) Required turbine: 2 units crossflow at 20kw capacity each4) Penstock lenght: 20 meters with a diameter of 1.2 meters5) Generator: 1 unit - 60kva, 3phase, 380 volts line to lineAs approved by the funding agency, crossflow turbine has to be used. I need your comments or suggestions regarding this design ( using crossflow turbine) at 4.43 meters headRegards,virgilio
- Virgilio:Where is the site located ?>An alternate solution would be a propeller turbine , either two propellers or a single one, two if the site needs to continue producing some power if one of the turbine needs to shut down.The tailrace has to be defined to determine if the turbine can be operational if the tailrace goes up too much during high seasonal flows and the site can not release the water fast enough down the stream.A Francis is an alternate solution but it would be quite large and heavy .There are other alternatives that could be considered to attain the harvested desired power like Axial pumps and in this case a vertical one which in a sense it is a propeller turbine but most of the time the blades are not adjustable to compensate the power under variable flow conditions.Reason why I suggest a propeller turbine with adjustable blades .Using two bankis , here you have a problem and it is the diameter and the length of each turbine and the calculations needed to have quite well evaluated to maximize the efficiency of each turbine to obtain the optimum RPM and at the same time to have the optimum efficiency ( to be able to use the water rear flow to harvest at least an additional 17 to 19 % power ) so you will need to get a good company that can supply a guaranteed efficiency % and there are a very few one available capable of doing such high analysis job.You have not informed about the tailrace behavior around the site to see how to implement a draft tube to see if the overall system can be made operational 100 % of the time or the need to shut down when the tailrace goes up too high ( the water going down stream is not released fast enough to keep the tailrace low).Propeller or any other turbine for such a site may have the tailrace problem and therefore the site needs a good analysis to see how to solve the problem is such problem can be present periodically during the water high flows..Nando----- Original Message -----From: virgilio, sr laborSent: Tuesday, March 26, 2013 01:00Subject: [microhydro] microhydro installationHi everyone,I have one microhydro site which i would like everyone to comment.Parameters are:1) Flow (Q) = 2 m3/second2) Net head = 4.3 meters3) Required turbine: 2 units crossflow at 20kw capacity each4) Penstock lenght: 20 meters with a diameter of 1.2 meters5) Generator: 1 unit - 60kva, 3phase, 380 volts line to lineAs approved by the funding agency, crossflow turbine has to be used. I need your comments or suggestions regarding this design ( using crossflow turbine) at 4.43 meters headRegards,virgilio