wuhorn,

You Texans do go in for the big stuff, don't you.

Your best bet is to find a civil or mechanical engineering firm around there and get out that checkbook. You need on-site, expert help with this project. Any advice you get here is well intentioned, but casual at best.

I have relatives in Terry County.

Good luck!

I'm not an expert in these things; but it strikes me that your best help may come from an electrical engineer. Seems like it will be easier to reduce power output of the generator by lowering the field current or something like that than "souping up" the turbines to put out more power from a given flow and head. Still, you need expert help of people with hydropower experience as lynlynch suggested.

Ed Weldon

Ed - This is a very intriguing concept and I will look at it further.

Are you sure water is getting to the runner? You say you have a speed problem. The speed is determined by the frequency and the number of generator poles. Is there a penstock or tail water restriction?

The generator might be re-wound for a slower speed.

If you go for a new runner for the low head, consider a Kaplan in place of the Francis.

What kw or horspower is the unit?

Don Jeerings 82 years old, retired

Water is getting to the runner. The Leffel turbine has a few frozen gates that will be replaced, most are operational. The penstock and water are not issues. There is plenty of water. The dam is very low and the turbine is undersized. The remedy lies in upgrading turbine horsepower so it can rotate the generator at 150 rpm. What is the cost to have a new runner designed, fabricated and installed. What would a turbine replacement (Francis to Kaplan) cost ? The two Westinghouse generators are rated 312.5 kva at 150 rpm. The existing turbines may rotate them at 120 rpm at full load.

Also do not forget that the Kaplan may need much more water flow for the same horsepower output. I believe, the easiest way would be to downgrade the generator whicn would be much easier and least expensive. You will have a smaller output but will save in the initial cost of the equipment and installation. Replacing the frozen gates also would add much more to the power of the turbiine.

If you do a search for micro hydro power systems you will find a number of companies who can probably help you. I would guess for little or no charge since they would like to sell you what you need to make your system work.

Converting to metric for us Aussies. 300cfs = 300 * 28kg = 8400 kg/s & 7 feets = 2.13m

So total available power m/s*g*h = 8400 * 9.8 * 2.1 = 175kW, even guessing an efficiency of say 50% still gives about 90kW. WOW!

Total available power is probably right. We have two generators and two turbines and their efficiency should be in the 80% range. Our production may be in the 270 kWh range, no?

So how do you expect your output to be greater than the total available input power?

With two turbines, only half the water can flow through each turbine, so according to ffej's calculations (which I have verified as correct), a 50% total efficiency would give each turbine/alternator a 44kw output. ffej's 90kW total was rounded to one digit of precision, which is appropriate, since your ∆y was given to one digit of precision.

GA, ffej!

You are right. Thought the same thing as soon as I posted my reply

However....our low flow range is 300 cfs and high is over 4000 cfs. I use 500 cfs in my calcs.

Now that is a different story! I presume that the head is more than 7 ft at high flow as well. Now - what fraction of that 4000cfs can actually flow through your turbines?

There's a lot of expert on this field.

I will have him look at your inquiry and do you have a fax number (he's old school)

FYI

My fax is 830 626 2803. I am travelling though and return to the office after October 5.

Maybe some more info of the turbine-generator set would be helpfull. Does the equipment have any manufactures name plate, can you post a pic.

What did you use for load on the generator? Did you measure the line frequency? 120 rpm could be the correct speed for the generator. That would corrospond to a 30 pole generator at 60hz. 150rpm for a 24 pole 60hz gen or a 20 pole 50hz machine.

If you've got the money, several large companies will engineer new turbines for these applications. Several U.S. utility companies hold on to their 100+ year old hydros as a source of renewable energy and had made substantial improvement to the output. Some of the units have been uprated by 50% or more with new turbines in the same bore and generator upgrades.

The 2 generators are Westinghouse - the plate says 312.5 kva at 150 rpm, 600 amps, 60 cps. I believe it has 64 poles. Both turbines are Leffel z 36 Francis type and controls are Woodward. I have photos to post. I had the generators refurbished by Bradleys of Corpus Cristi and do not believe they were loaded. My reference to load is during power production, the induced resistance should slow turbine rpm to the low 120's (according to Leffel information). I do not believe a load was induced by Bradleys or line frequency measured.

If it is worthwhile, we will overhaul the equipment. It seems to me technology should be available to upgrade our equipment to perform to a reasonable financial return. Owning renewable power production would be fun. This facility will never generate a significant amount of power, but if it can produce 200+ kWh, I will look hard at going forward. If there is an engineering solution the risk becomes mechanical. Are the technicians available in our area to perform the work etc.

You seem very knowledgeable - I have another, more theoretical question in this segment and will post it soon. Do not want to dilute this thread.

Dams are being removed from smaller NW rivers. Maybe you could secure the turbines that are being removed and have the correct size turbines for the generators. The Salmon River in SW Washington is about to remove a dam. The Sandy river in NW Oregon removed a dam about a year and half ago and the process continues...

Try Canyon Industries. There in Demming, Washington and design small hydro units. If they can't help, they can point you in the right direction.

New Braunfels, Texas is one of the most beautiful spots in all of the US...and the Guadalupe a beautiful river...

You may want to try contacting Southwest Research Institute in San Antonio for advice. Years ago, they had some pretty significant technical capabilities...

From the figures you have given, the hydraulic power available (ie at 100% efficiency) ranges from about 150 to 370kW.

At 70 % overall efficiency (generator and turbine each roughly 85% efficient) you should be able to get about 105 to 260kW.

Have you tried going back to the turbine manufacturer (whoever that may be now) and seeing if they still have a copy of the performance curve? This will tell you what it could achieve (when new!) over the range of flows available.

After freeing up the gates and getting the maximum flow you can to the turbine, if you still can't get to rated speed, the simplest is to de rate the generator and reduce flow to the turbine accordingly.

The turbine should operate fairly efficiently over the range of available river flows you have quoted, although if you decide on replacement, a Kaplan would probably be better.

Flows through the turbine should be about the same for either as the flow required is simply a function of power demand, turbine efficiency and available head.

Surprising that the installation passed it's commissioning tests if the turbine is so badly undersized.

Is there wear (cavitation pits etc) showing on the impeller?

Are the bearings partly seized?

Is the volute smooth?

All these and many more things can affect the performance.

When we made pumps, if the efficiency didn't come up to scratch, a good polish of the passageways through the impeller normally brought it up. More commonly our efficiency was sufficiently better than guarantee to compensate for the motor being a little under.

Your projections are similar to mine. My go forward number is 200 kWh. If that threshold can be assured, I am willing to spend what it will take. We would overhaul most components and anticipate cost to be around one million dollars.

I brought Leffel (turbine mfg) down twice. They were more interested in selling me a new and larger Leffel turbine, than arriving at a more realistic solution. Replacing the Leffel runner with one of higher hp seems to be a more reasonable approach. Replacing the turbine, civil work, removal and installation are not feasible.

I am unfamiliar with "rate the generator". Does this imply reducing generator capacity which reduces load on the turbines. The lower "rating" comes in synch with the undersized turbine.

This hydro plant was built in the early 1920's to supply power to a privately owned Mill. We have no record of commissioning tests. Lockwood & Green, the Boston engineering firm, specified 45 inch turbines. The builders purchased and installed 36 inch turbines and the mismatched equipment was abandoned. The equipment is old but is in very good condition. It is part of a greater aquisition and a gem.

One of the units turns freely and the other does not. Replacing or repacking bearings will be simpler than other issues. By volute, do you mean "runner" ? If so, the runners are in good condition and smooth. Other than deterioration due to age, everything seems in good shape.

Your comments about efficient water passage brings up a thought. Would teflon coating or alloy plating the runners and gates enhance thir performance ? They are cast iron and a thin coating of an abrasion resisting material may be worth a look.

Thank you for your help.

Hi wuhorn

Your comments about efficient water passage brings up a thought. Would teflon coating or alloy plating the runners and gates enhance their performance ? They are cast iron and a thin coating of an abrasion resisting material may be worth a look.

Abrasion is unlikely to be a significant factor as your river flows will be reasonably clean. Even in flood sand will still be dispersed in a lot of water and is unlikely to cause drastic wear.

If it had been installed with rough passages a clean up may help. If visually smooth gains are unlikely to be worth the effort.

In our case we were working with cast impellers and volutes, so smoothing the passages was often worthwhile.

As far as de rating the generator is concerned, it is simply a matter of reducing the field current, which means higher revs are needed for the same power. this will reduce the load on your turbine, allowing it to spin faster.

If you can get a performance curve for the original turbine, you should be able to work out the power you can extract from it at 150 rpm. This will tell you if it will generate your target 200kW. If it won't then a new runner will be needed.

Good luck

wuhorn,

I don't know much about rewiring generators but there is a neat website out there that works with small hydro-electric plants like yours. They have an excellent selection of information that may help you out a bunch. The website is www.frenchriverland.com

I also like to say, I live down river from New Braunfels at Victoria, TX. We do come to New Braunfels often, be nice to come visit and see old stuff like you have.

If it is of help, there are hydro-electric plants at Seguin, Gonzales, and used to be one at Cuero, too. I have no contacts to any of these units.

Teco/Westenhouse up in Roundrock may be able to rewire/refurbish your equipment. If you need machine shop services, I can recommend several within 100 or so miles of New Braunfels.

Ken S.

There's an independant engineer in Bastrop that is excellent at thinking outside the box. He has extensive experience in the power industry. I'm betting he could help you turn this into a reliable, profitable plant. If you're interested, I'll provide contact information.

Mr. Alderson -

Finding a dependable engineer in this field would be very helpful. One problem is the lack of hydro-electric experience in our area and Bastrop is nearby. I would appreciate his contact information posted on this forum or faxed to my office 830 626 2803.

Thank you

.

wuhorn, try getting a hold of these people. They had a small dam with much the same problem. High levels lots of spillage, low levels no spin. They had a company in Canada build them a variable pitch turbine to address this problem. The system is patented so what information you get might have to kept to ones self. They had a special on Discovery or PBS channel, very interesting.

http://www.columbiapower.org/news.asp?ID=5

Cheers Robert