5 - pelton turbine

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Design of Peltonturbines

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When to use a Peltonturbine

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Energy conversion in aPelton turbine

Outlet Outlet of

the runner

Inlet of

the runner

Outlet of

the needle

Inlet of

the needle

2

2c

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Main dimensions for thePelton runner

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The ideal Pelton runnerAbsolute velocity from nozzle:

n1 Hg2c = 1Hg2

cc

n

11 =

=

Circumferential speed:

nu1

1 Hg2

2

1

2

cu == 5.0u1 =

Euler`s turbine equation:

)cucu(2 u22u11h =

1)05,00.15,0(2)(2 2211 === uuh cucu

1c u1 = 0c 2u =

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The real Pelton runner For a real Pelton runner there will always be losWe will therefore set the hydraulic efficiency to:

96.0h =

The absolute velocity from the nozzle will be:

995.0c99.0 u1

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From continuity equation:

u1

2

s c4

dzQ

=

u1

scz

Q4d

=

Where:

Z = number of nozzles

Q = flow rate

C1u = nHg2

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The size of the bucket

and number of nozzles

4.3

d

B1.3

s

>

Rules of thumb:

B = 3,1 ds 1 nozzle

B = 3,2 ds 2 nozzles

B = 3,3 ds

4-5 nozzles

B > 3,3 ds 6 nozzles

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Number of buckets

17z empirical

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Number of buckets

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Runner diameterRules of thumb:

D = 10 ds

Hn

< 500 m

D = 15 ds Hn = 1300 m

D < 9,5 ds must be avoided because water

will be lost

D > 15 ds is for very high head Pelton

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Speed number

zQ =

5,0u

0,1c

1

u1

=

=

4

dc

4

dQ

2

su1

2

s =

=

D

1

Hg2D

Hg2

Hg2D

u2

Hg2 n

n

n

1

n=

=

=

=

4

z

D

ds =

4

zd

D

1zQ

2

s ==

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For the diameter: D = 10 dsand one nozzle: z = 1

09,0

4

1

10

1

4

z

D

ds =

=

=

For the diameter: D = 10 dsand six nozzle: z = 6

22,04

6

10

1

4

z

D

ds =

=

=

The maximum speed number for a Pelton

turbine today is = 0,22

The maximum speed number for a Pelton

turbine with one nozzle is = 0,09

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Dimensioning of a

Pelton turbine

1. The flow rate and head are given*H = 1130 m

*Q = 28,5 m3/s

*P = 288 MW

2. Choose reduced values

c1u = 1 c1u = 149 m/su1 = 0,48 u1 = 71 m/s

3. Choose the number of nozzlesz = 5

4. Calculate ds from continuity for one nozzle

m22,0

cz

Q4d

u1

s =

=

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5. Choose the bucket width

B = 3,3 ds= 0,73 m

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6. Find the diameter by interpolation

D/ds

Hn [m]

10

15

400 1400

m0,3d65,13D

65,138H005,0d

D

s

n

s

==

=+=

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7. Calculate the speed:

8. Choose the number of poles on the generator:

The speed of the runner is given by the generator andthe net frequency:

where Zp=number of poles on the generator

The number of poles will be:

rpm452D

60un

2

D

60

n2

2

Du

1

1

==

==

]rpm[Z

3000n

p

=

764,6n

3000Zp ===

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]rpm[6,428Z

3000n

p

==

m16,3n

60uD

2

D

60

n2

2

Du 11 =

=

==

9. Recalculate the speed:

10. Recalculate the diameter:

11. Choose the number of buckets

z = 22

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12. Diameter of the turbine housing (for vertical turbines)

13. Calculate the height from the runner to the water levelat the outlet (for vertical turbines)

m4,9BKDD gsinHou =+=

K

z

8

9

1 64

m1,3DB5.3Height =

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Given values:

*Q =28,5 m3/s

*H =1130m

Chosen values:

c1u = 1

u1 = 0,48

z = 5

B= 0,73 m

z = 22

Zp = 7

Calculated values:

ds = 0,22 m

n =428,6 rpm

D=3, 16 m

Height= 3,1 m

Dhousing= 9,4 m

*P= 288MW

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GE Hydro

*Q=28,5 m3/s

*H = 1130m

*P =288MW

Jostedal, Sogn og Fjordane

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Jostedal, Sogn og Fjordane

GE Hydro

*Q=28,5 m3/s

*H =1130m

*P =288MW

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ExampleKhimti Power Plant

1. The flow rate and head are given*H = 660 m

*Q = 2,15 m3/s

*P = 12 MW

2. Choose reduced values

c1u = 1 c1u = 114 m/su1 = 0,48 u1 = 54,6 m/s

3. Choose the number of nozzles

z = 1

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ExampleKhimti Power Plant

4. Calculate ds from continuity forone nozzle

5. Choose the bucket widthB = 3,2 ds= 0, 5 m

mcz

Qd

u

s 15,04

1

=

=

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6. Find the diameter by interpolation

D/ds

Hn [m]

10

15

400 1400

mdD

Hd

D

s

n

s

7,13,11

3,118005,0

==

=+=

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7. Calculate the speed:

8. Choose the number of poles on thegenerator:

The speed of the runner is given by

the generator and the net frequency:

where Zp=number of poles on the

generator

The number of poles will be:

rpmD

un

DnDu

61360

260

2

2

1

1

=

=

==

]rpm[Z

3000n

p

=

59,43000

=== nZp

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][6003000

rpmZ

np

==

mn

uD

DnDu 74,1

60

260

2

2

11 =

=

==

9. Recalculate the speed:

10. Recalculate the diameter:

11. Choose the number of buckets

z = 22