Hi Jean,
I've made some calculations using the turbine affinity laws for
constant diameter (e.g. keeping the same turbine).
Flow & rpm
Q1/Q2 = N1/N2
Head & rpm
H1/H2 = (N1/N2)^2
Power & rpm
P1/P2 = (N1/N2)^3
First, assuming you want to increase from 125kW to 200kW use the power
affinity law to calculate the new rpm
200/125 = (N1/900)^3
which gives N1 = 1053 rpm
Then the required head is
H1/30,5 = (1053/900)^2
which gives H1 = 41,7 meters
Then flow rate
Q1/500 = (1053/900)
which gives Q1 = 585 lps
I expect that the turbine & shaft were conservatively designed for
much more power and that you shouldn't have to worry about that.
You would need a speed reducing pulley ratio of 7:6 to run the turbine
at ~ 1050 rpm and the generator at 900 rpm. If you allow the turbine
to run at the higher rpm with higher head, in theory, cavitation
should not be more of a problem that it is now.
If you can develop 41,7 m of head available at this site, it may be
the easiest means of increasing the power. It doesn't use much more
flow, so you still might want to build a copy and run two units for
400kW.
Joe
http://h-hydro.com
--- In [email protected], "jean vadis" <[EMAIL PROTECTED]>
wrote:
>
> Hello to the group-
> I would like to increase the power close to the max gen
rating.-if
> possible!
> Here is the situation
> the turbine is designed for 30,5m head and 500l/sec flow( 125 kw).
, it is
> mounted on the generator shaft that is rated 200 kw at 900 rpm.
> I have a site that has way more flow and I could use more head
>
> Option 1 - -can I install a runner that will take more water,but
stiil fit
> into the spiral case without any modifications and turn at the
same
> rate.Will not the turbine and shaft be overstressed??
>
>
> Option 2-make another twin (copy) turbine and join the shafts by
clutch-that
> will also increase the rpm
>
> option 3-increase the head -some books say that it could be done up
to 25%
> of the design head-what about increased rpm(will the generator and
> electrical controls and panels take it?) ,cavitation and stresses
on the
> turbine and shaft??
>
> Option 4- the easiest and cheapest way is to make a copy the
turbine ,
> controls and panels, get another generator and install them both
as 2
> identical units .
> Greetings-Jean
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