Looking for feedback on my hydro project

[Lowhead]

Hello all.  I have been lurking here for a few months and finally am ready to join in this discussion forum.  I am a mechanical engineer who has always had an interest in hydro power and have decided that the time is right for me to try to move forward with my little project.  I have put together a crude web site on googlepages with some pictures of my site and hopefully all the pertinent information. If anyone has any comments or feedback, I would appreciate some.  The site has some historical info regarding the old mill and is there mostly to schmooze my local conservation commission. Feel free ignore it.

Lowhead

[hiker]

here you go......

       http://boyceaj.googlepages.com/cordavillemillpondmicrohydrosite

[willib]

Others have more expierence than me in hydro , but it seems to me that you have two options

one is to use the dam water pressure at the bottom of the dam , by drilling a hole in the dam or several, and piping the flow to individual pelton wheels ?

that would depend on the the depth of the water at the dam ?

the other option , again as i see it, is to use a water wheel spanning the dam , generating more torque than a single slimmer wheel?

 just some ideas of mine.

[Nando]

Why don't you explain in a short sentence what you have in water volume and head.

Going to your site to read and read and read, trying to see what your program is, does not call my attention.

I have hydro experience and if you want a GRID tied system I could say :

A Turbine and an induction motor plus the protection circuits and using the GRID power to convert the motor into a generator.

The GRID controlling the delivered power as limited by the available hydro power driving the motor via the turbine.

Cheaper that using generators that need synchronization and additional controls.

Nando

[Lowhead]

Sorry my googlepage link didn't quite work.  Nando has suggested I write a short description of my site so here are the relavent facts:

2.4 meters of head created by an earthen dam formerly used to power a cotton and woolen mill. I don't have an outlet pipe and I doubt my local conservation committee is going to let me breach the dam to install one.  There is a concrete outlet structure on the opposite side of the river from my property that has steel plates blocking the flow.  It is possible that I own or have control of half of it but I am not sure. It looks like the perfect spot to install a turbine.

There is between 1 and 100 CFS of flow according to the US Geological survey.  Looking at their chart, there is generally between 12,000 and 30,000 gallons per minute of flow.

According to local historical commission, the former mill had an 85 hp turbine back in 1855.  I'm not quite convinced that is true.  I think they have misinterpreted an old brochure from the 1929 auction of the mill.  It lists an 85KVA generating unit driven by a 15 inch Leffel turbine.  I found a chart showing that a 15 leffel with 2.4 meters of head would only generate about 26 hp. (On my site, I still call it 85hp because I think it helps my case before my conservation committee.)

I have a tentatively identified what I think is the best fit turbine for my site but it  is very dependent on my local authorities and how much power they will let me take.  I am curious to know if anyone has any opinion on the Chinese built turbine I show at my googlepage.  Any thoughts on siphon feeding it?  Any thoughts on grid connecting it?  I have spoken with my local utility and they say I need to install what they call a relay but it is really a power monitoring device that allows them to disconnect me if the grid goes down or the power is dirty.  I don't know what that costs or where to get one.  The Chinese unit does come with an ELC.

I have spoken with FERC and they pretty much told me to try to fly under the radar.  Any thoughts?  I may still have to go through FERC if I want to apply for some state available grants.  Unfortunately, I am ineligible for the low impact hydro exemption program they offer.

There are lots of pictures and more info on the site link if I can get it to work.

http://boyceaj(dot)googlepages(dot)com/cordavillemillpondmicrohydrosite

I apologize in advance to any wind or solar people who might be offended by my site but please remember, I am trying to sell this to my local conservation commission.

Lowhead

[hiker]

didnt that link work i posted?

or is it the wrong one?

[Lowhead]

You had the right link.  I didn't realize you had reposted it.  Thanks

Lowhead

[scottsAI]

Hello Lowhead,

For the generator I agree with Nando. 3 phase Induction motors in the 30hp range are cheap relative to any generator you can build or find. Ebay watching for a few months, looks like $300 for a new 30hp motor inverter duty or continuous duty, you have to pick it up, shipping is a killer. Induction generator is safe, if grid goes down, then the field fails and the generator stops producing. You will want to put a detector on it for this, the generator will double speed with no load. Most motors are not made to run double speed...

Generator will need speed-up gears, consider flat belts, new flat belts claim efficiency on par with gears. Belts are easy to change ratio, lower cost than gears. New belts last long, not as long as gears.

Not talking V-belts.

Question about the turbine, your web says Banki is not good due to low head.

Interesting, low head is what Banki is all about, 3 feet and up, where did you read differently?

Like you say an advantage is you can build it.

What about a plastic pipe Banki? Might not last forever, is cheap can test how things work, much easier to change. Later build it out of metal if needed. Banki does use a nozzle, make sure the pipe feeding the nozzle is several times larger in cross area than the nozzle area. Low preforming Banki the pipe to nozzle area is generally the problem. The pressure of the dam should be the same just before the nozzle, any drop will reduce the power available for the generator.

Any thoughts on siphon feeding it?

Yes, good idea, make sure you can remove air that accumulates in the low pressure area of the pipe.

(highest point, will be negative pressure)

DO NOT MESS with the dam structure. Friend just wanted to drill a hole... hours later the dam failed, water leaked around the pipe and washed it out, what a mess.

Have fun,

Scott.

[Lowhead]

Thanks for the feedback Scott.  I am very interested in the 3 phase motor thing if I end up building my own unit.  There are some grants available from the state but they basically exclude homebuilt DIY stuff and you have to hire a licensed contractor so that is one of the reasons I have been exploring store bought turbines.  I don't know enough about converting a 3 phase motor and would love to find more resources on this.  What sort of detector are you talking about?  I understand I need some special equipment required by the utility that they call a relay - made by Beckwith Electric, Basler Electric or Schwietzer.  I assume you mean some sort of device to measure current flow and disconnect the motor so that it won't run as a motor if the water flow stops?

Definately I would use one of the new style flat timing or micro V belts.  I am surprised at the comment that the belts are approaching the efficiency of gears.  Gears are usually way less efficient than belts from what I remember due to the friction of gears faces sliding.

I am sorry about the confusion on the Banki.  I should clarify my web site.  In my situation, using a Banki in the concrete structure would result in loss of about 1/3 meter of head out of 2.4 meters.  If I had 5 or 10 meters, that would be a lot less significant percentage.  The Ossberger has some sort of draft tube that supposendly can reclaim that but I doubt a home built one can do that easily.  I have read the OSU bulletin on Banki and I think I can figure most of it out.  I wouldn't want to build one out of PVC pipe.  I own lots of welding equipment and have access to a full machine shop. If I can't get any grants and try to fly under the FERC radar, that is definately the way I am going.

Thanks for the tip on venting the air at the top of the siphon.  I think that can be done with a commercial vacuum breaker.  I really would like to avoid doing the siphon feed if possible but there is no way I am going to drill a hole in the dam.  I might be able to take out one of the cut granite blocks on top of the dam during the low water months if I can get a backhoe in there without the con-com freaking out.  I was thinking I could replace it with a welded steel box with a pipe flange welded on.  Ideally I can use the concrete structure.  I think by riparian rights, I own half of it.

Andy

[scottsAI]

Hello Lowhead,

I take it you do not have 3 phase? Farms can often get it at 440vac.

Single phase:

26hp = 19,473watts at 220v = 88.5 amps. Any problems?

You can take up to 57% power off one phase if motor wired delta

So the motor will have to be that much larger.

Most motors this big will be 440volts or higher. You do have your challenges.

I assume you mean some sort of device to measure current flow and disconnect the motor so that it won't run as a motor if the water flow stops? Yes.

Have you considered bypassing the dam on your property? Can use up and down stream pipe to control where and when you re-enter the river. No risk to the dam by modifying anything, maybe get higher.

With this much power rather difficult to go under the wire. If your trying to cancel your electric bill, then a much smaller generator is needed. Even for my house 2 HP would be too big.

You could always put up a small solar panel, get netmetering then add hydro:-)

Have fun,

Scott.

[finnsawyer]

When having a pipe passing through an earthen dam it is necessary to weld a large square plate around the pipe.  Doing this would require draining the pond.  It's easier on a new dam.  Years ago B.D. (before divorce) I made a triangular shaped pond 400 feet by 200 feet and placed a four inch diameter pipe (with the big plate)through the base of it.  A barrel filled with rocks was placed around the pipe entrance in the pond. That was over twenty years ago.  The dam is still doing fine.  This reminds me.  I need to remind the current owner to open the valve to wash away the large tadpoles and silt that builds up.  

[Lowhead]

Thanks for the advice on the pipe flange.  If I take out one of the cut granite blocks at the top of the dam and replace it with a steel box, I will weld a flange around it to keep it in place.  

Andy

[Lowhead]

I don't have 3 phase.  It probably passes by on the poles but I only have the regular 220V, 200 amp service panel.  My utilities come in underground so it would mean digging up the yard to add 3 phase.  It might not be such a bad thing to do since I am trying to build a garage as part of the same project with the conservation committee.  The yard will be dug up anyways.  I will take a look to see where the transformer is on the poles.  I don't need to have 3 phase power to do the AC motor thing do I?  As far as bypassing the dam, that just isn't going to fly with the conservation committee since it would disturb a lot of wetlands and they are very sensitive to that. I thought about getting the net metering installed with a solar panel and an Outback inverter and then adding the turbine and more inverters but that pretty much forces me down the DC path doesn't it?  I would rather not have to deal with batteries.

Andy

[finnsawyer]

Actually the flange is there to break up the flow of water that will tend to follow the pipe.  After all, the pipe is a relatively smooth surface.  When the water encounters the flange it has to flow away from the pipe, which results in it having to find a less disruptive path.  Keep in mind that water will tend to flow downward due to gravity even in the ground.  All earthen dams have some seepage through the base, so adding this slight amount of water to that flow will usually have a negligible effect.

[scottsAI]

Hello Lowhead,

DC...

Nope, the solar needs DC, the Hydro can be AC all the way.

The solar and hydro would be separate paths.

Same path once connected to the Grid.

3 phase.. single phase.

If you have single phase, use one phase of the 3 phase motor.

3 phase is not required.

Remember must limit the power to 57% of motor rated power.

Have fun,

Scott.

[Lowhead]

So I think I am back to building my own crossflow unit.  It means giving up some watts due to head loss and efficiency but since I can basically bolt it into the concrete gate house, I won't really need a tailrace.  I think that will better fly with my conservation committee since there is basically no wetlands disturbance.  I have been doing some research and I have a copy of the OSU bulletin.  There is very little information on building the nozzle.  I have run across some references to work done on optimizing crossflows by Desai and Aziz but I haven't found a copy.  It looks like it was published in Waterpower '93.  Anybody out there have a copy or know where I can get it?  I am seeing some units with nozzles that are the full width and I some where the runner is 1.5 times the width of the nozzle.  

Also, I have read that it is best to keep the number of blades to a prime number to reduce noise and vibration but most of the designs I see don't follow this rule.  Any thoughts out there?

Low Head

[scottsAI]

Hello Lowhead,

Your link no longer works?

Crossflow (Banki) turbine how big do you plan to make it, at the 30ph range?

Only thing I can think to help is to make sure the pipe feeding the nozzle is couple times the area of the nozzle. I mentioned this above, worth repeating. The nozzle converts PE to KE. I came across something on sizing the nozzle, can't find it, will keep looking. I think I have basically the same web finds as you have mentioned OSU

http://www.builditsolar.com/Projects/Hydro/BANKITUR.pdf

The banki can be fitted with downdraft to recover the last 1/3 meters, I don't think it would be worth the trouble.

Have fun,

Scott.