C if l P T biCentrifugal Pumps as Turbines:

A Review of Technology and ApplicationsA Review of Technology and Applications

Arthur Williams – University of Nottingham(School of Electrical & Electronic Engineering)

C if l P T biCentrifugal Pumps as Turbines:

A Review of Technology and ApplicationsA Review of Technology and Applications

ThThemes:

1. Improved Prediction using Cordier Diagram

2. Applications in Water Industry & Rural Development

Typical pump and Pump as Turbine (PAT) curvesTurbine (PAT) curves

16

18 7000

12

14

16

5000

6000

)PAT Head

10

12

ad (m

) 4000

pow

er (W

Pump best

PAT Head

Eff. 73%

6

8Hea

2000

3000

Turb

ine efficiency: 72%

PAT Power

2

4

1000

00 10 20 30 40 50 60

Flow (litre/s)

0

( )

End-suction centrifugal pump with 4-pole motor

Pump as Turbine (PAT) efficiencies can be as good as pump mode – but not always

1.15

good as pump mode – but not always

1 05

1.1

1

1.05

ency

ratio

+/- 5%

0 9

0.95

Pum

p ef

ficie

>2% lower efficiency

+/- 2% efficiency

0.85

0.9

PA

T:P % y

>2% higher efficiency

Double suction pumps

0.8

Double suction pumps

Cylindrical volute pump

0.7510 100 1000

Pump Specific Speed (Nq - metric units - logarithmic scale)

Using dimensionless parameters for PAT performance predictionperformance prediction

90 End‐suction Pumps

70

80End suction Pumps

End‐suction PATs

Pumps PSingh

50

60

fic Speed

Pumps PSingh

PATs PSingh

Pump Trend Spe

ed

20

30

40

Specif Pump Trend

PAT Trend

pecific

 

0

10

20S

1 2 3 4 5 6 7Specific Diameter

Specific Diameter

Turbine and Pump Specific Speeds

80Nqt

60

NqtP Singh's Data

P Singh Trendline

40Linear Correlation

20

Correlation

20

Nqp

00 20 40 60 80 100

Specific Speed of PAT is not = Specific Speed of PumpSpecific Speed of PAT is not = Specific Speed of Pump

Turbine and Pump Specific Speeds

80 End suction pumps

60

80Nqt End-suction pumps

P Singh's Data

40

P Singh Trendline

Outside +/- 3% error range

20

0 Nqp0 20 40 60 80 100

Cordier Diagram for Pumps and PATs

100

End‐suction Pumps

End‐suction PATs

Pumps (PSingh)

(log scale)

Pumps (PSingh)

PATs (PSingh)

Pump Trend

ific Speed (

PAT Trend

Unusual Pumps

Spec Unusual PATs

A conclusion: Trend lines h ld b b d

Specific Diameter (log scale)

should be based on similar designs of pump

10

1 10

Specific Diameter (log scale)

DH‐supply Energy Recovery Applications

Control Valve

Applications

PAT used in district heating (DH)

Circulation Pump Approx. 1 kW unit

Prevents heating from closing down in event of

PAT

closing down in event of electric supply failure

PAT(Wollerstrand & Fredericksen, 

Lund University, 2008)

DH‐return Heat Exchanger

Applications in Water Industry

13 kW energy recovery unit in13 kW energy recovery unit in Switzerland.

Advantages quoted:

• Less surge than Pelton in case of loss of mains

• Easier maintenance and• Easier maintenance and quicker delivery of parts

Applications in Water Industry

Control of Pressure => Flow Reduction of 25%

0:00 6:00 12:00 18:00 24.00

(Graph from J Thornton, 2003)Time of Day

Applications in Water Industry

Significant Pressure Reduction Needed

Could be achieved by valve and PAT

in parallelTime of Day >

in parallel

Applications in Water Industry

Example from www.atb-becker.com

(Austria)

Typical system with valve and PAT

in parallel

Positive displacement

PAT from in parallelPAT from Zeropex

(Norway)

Applications in Rural Electrification

Border Green Energy have built six village Pump-as-Border Green Energy have built six village Pump-as-turbine projects on the Thai/Burma border area from 3 kW to 10 kW in capacity, and all produce power at

expected levelsexpected levels.

(Mae Wei, Thailand)Thailand)

Applications in Rural Electrification

Heksa Prakarsa Teknik include Pumps-as-turbines among their turbine options and

have installed several in Indonesia. These projects use an electronic load controllerprojects use an electronic load controller

designed by Dr Nigel Smith for use with off-grid asynchronous (induction) generators.

Conclusions:

1. Pump-as-Turbine prediction is better with Cordier plot

2. Similar Designs of pumps will have similar PAT trends

3. Useful for pump manufacturers

(in combination with CFD to identify effects of geometry inidentify effects of geometry in turbine operation)

Conclusions:

1. Pump-as-Turbine prediction is better with Cordier plot

2. Similar Designs of pumps will have similar PAT trends

3. Useful for pump manufacturers

4. Energy recovery applications in Water Supply & District Heating

5 Wid d ibl i R l El t ifi ti5. Widespread use possible in Rural Electrification