Francis Turbine/Generators

Look up the following web site http://www.alfredssonsmaskin.com .they make the Francis Turbine/Generator. Things like these when available and manufacturerd by companies with scores & scores of years of experience, it will not be easy to manufactuer it in your back-yard. There is engineering & metal technology involved and to me is simply a waste of time and energy not to mention money which one can never have to carry out all the R & D. Suggest you decide or buy.

Hi Dendalo,

A very warm welcome to CR4. Please could you specify if this 'Francis Turbine' is in situ? If so, is it already fitted with a generator? What is the approximate mechanical output, i.e. rpm, horsepower/wattage size, etc. We can but search around for you. I guess that two generators would be 'one' too many.

I may be wrong, but it sounds very much like you are asking if it is possible to extract more power from the turbine with two generators than with one and the answer to that is very simply: NO. The same answer holds for producing more electrical power with two generators rather than one.

In the conversion of mechanical to electrical energy, the law of conservation of energy rules, no matter how many generators you hook to the turbine. In fact, due to likely increased frictional losses, you will get less electrical power.

I think you sensed this by your "conservative" choice of 110% of the power with two turbines that you got with one. Otherwise you would have said 200% of the power.

If I misinterpreted your question, I apologize, but that is how it came across to me.

Simply stated, I think our guest Dendalo is asking a very simple question;

"What is the best generator to fit a Francis Turbine"

Dendalo may be in luck, as high efficiency can now be obtained from direct drive low rpm power sources. Windmill technology has seen to that. Gearboxes are inefficient as well as costly both to buy and maintain.

His post says otherwise:

"I would be grateful for anyone's help, this is a relatively simple one, does anyone know if it is possible to design a twin Francis turbine? That is, a single turbine powering two generators. If it is, will the turbine be able to power each of the two generators so that they operate at or can better 55% efficiency, or will the 'twin' turbine/generator simply produce just half the power of a single turbine generator?"

I stand corrected, but in my view that should have been his question. It is far more likely that the turbine will get blocked with an object, or the filter clogs, whatever, and so lead to a power down. If a single generator is chosen slightly over-size, and so operates at say 75% of designed load, and then suitable overload cut-out protection is employed, it should run trouble free for as long as it is regularly inspected and maintained. Some generators are nearly a century old, and still going strong. My Grandfather said "One pair of good shoes will outlast a dozen poor"

Alastair:

I'm not sure what he meant or should have meant either.

Don't mistake my blunt style for disrespect.

In his case though, I am suspecting the "worst" as indicated by my post #3, because he makes a big point of wanting the two generator's output summing to a value greater than from one.

Regards,

Greg

Hi Greg,

If engineers were not blunt and too the point, Coffin Carpenters would profit by it.

So let's be 'Blunt'.....CR4 lists about a dozen Flywheel Battery Manufacturers, The beauty illustrated above courtesy of Active Power Inc. Only a 14 inch diameter rotor, but with a whopping quarter megawatt output if so needed.

That should give enough time to unblock the Francis Turbine. "Forget TWO Generators"....a blooming waste of time and space and money.

There.... I too can be 'Blunt'

http://www.globalspec.com/Supplier/Profile?vid=111273&Comp=2528

Alastair:

I agree these things are very interesting, with their high energy storage densities.

I've seen a number of high-tech flywheel energy storage devices that were configured to "store" electricity at several trade shows, and they are definitely impressive. I know a number of electric utilities use them, and their possible use in vehicles has been a topic of much discussion overtime, with a number of prototypes having been built including at least one public transit bus that was put in operation.

Regards.

Greg

CR4's Stirling Stan, has just told me about a friend of his who had developed a prototype spinning high powered magnetic sphere, only two inches diameter, but will deliver 600 watts, nearly a whole horsepower. I wonder for how long? A sphere is ideal for automotive applications, no objections to which way you turn. This is in my view, very worthwhile research. I hope our browser responds to our suggestions soon.....we are here to help if we can.

I am guessing here, but maybe the idea is that if one generator developes a fault, that the other one can step in so to say...

Though of course the Turbine is still a single point of failure and repairing a still turning damaged Generator would be hair raising to say the least.....unless the fault was only in the control circuitry....but even then.....

Basically we need a lot more info.....as usual.

<but maybe the idea is that if one generator developes a fault, that the other one can >--that's what our friend from Frankfurt am Main guesses.

Unfortunately all of us have to guess due to insufficient problem statement.

Assume again he asks { 'Turbine is infallible, one Generator could fail -and he wants redundancy. He asks }"Can we take55%(of turbine's max possible) power output out of one-of -two gensets in case of failure to the other? The Answer is YES , Probably 60% for an hour if genset windings and body are generously overdesigned!

His next question will be--can this be done?

Yes- if you use two giant pneumatic clutch couplings out of the Turbine Output Shaft---to drive 2 Generators.

Did somebody use anything like that before?--ask IEEE and the French-Russian companies.