4 - TEA Water Services - Pump Curves Final MFtea.ie/wp-content/uploads/2011/08/4-Water-Services-Pump-Curves.pdf · curve or the pump curve must be changed. ... • The performance

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Performance Curves


Performance Curve

Characteristics


Performance Curve

Characteristics


Operating Point

• The operating point of a centrifugal pump, also

called its duty point, is given by the intersection

of the pump characteristic curve with the

system curve.

• The flow rate Q and the developed head H are

both determined by the intersection.

• To change the operating point either the system

curve or the pump curve must be changed.


Pump Operating Point




Pump Range


Parallel Pumping



Multi-Stage Pump Range


Examples 2


€252,585.63145093.0%185.369%680 @ 69 mExisting

Pumps

€223,300.81€67,033.10153596.4%250199.887.3%800m3/hr @

80m.E4

€0.00€55,759.15145096.0%200720m3/hr @

80m.D3

€222,099.22€55,301.74140596.7%250199.387.5%800m3/hr @

80m.C2

€225,125.73€62,425.00145095.4%250199.387.5%800m3/hr @

80m.B

€226,419.56€52,777.50145095.4%250200.487.0%800m3/hr @

80m.A

1

COST PER ANNUM

PRICESPEED

MOTOR EFF.

MOTOR KW

POWER ABSORBED

kW

PUMP EFF.

OUTPUTPUMP COMPANY

Coolcorcoran Pumphouse

Coolcorcoran Pumphouse


Central Regional Water Supply

Coolcorcoran Station


Electricity Cost /

Consumption Chart


€325,507.

74145093.0%185.369%441050

Existing

Pumps

€298,179.

58€93,279.98135095.5%2503.9199.287.0%531,200D3

€296,626.

56€104,145.00132996.0%2504.6199.287.0%531,200C2

€296,342.

71

82855+1362

0145095.0%2505.8180.588.0%531,100B

€303,234.

40

102150

+13620145095.0%2504.2m181.486.0%531,080A

1

COST PER ANNUM

PRICESPEED

MOTOR EFF.

MOTOR KW

Pump N.P.S.H.

POWER ABSORBED

kW

PUMP EFF.

HEAD M.

OUTPUT M3/HR

PUMP

Lough Guitane Pumphouse

Lough Guitane

Pumphouse



Kilsarcon Pump Station



€29,516.52€66,587.053.66m29007556.278.6%150m3/hr @ 108m.H

€29,182.37€75,542.201.92m14507555.579.5%150m3/hr @ 108m.G

4

€30,129.85€63,348.892.1m14507557.377.0%150m3/hr @ 108m.F3

€29,516.52€54,820.503.66m29007556.278.6%150m3/hr @ 108m.E

€29,182.37€69,689.001.92m14507555.579.5%150m3/hr @ 108m.D

2

€29,516.52€61,026.703.66m29007556.278.6%150m3/hr @ 108m.C

€29,182.37€72,430.031.92m14507555.579.5%150m3/hr @ 108m.B

€30,129.85€54,888.602.1m14507557.377.0%150m3/hr @ 108m.A

1

COST PER ANNUM

PRICEPUMP NPSH SPEED

MOTOR KW.

POWER ABSORBED

kW

PUMP EFFICIENCY

OUTPUTPUMP

Crohane Pumphouse

Crohane Pumphouse


Mid Kerry W.S.Crohane


Mid Kerry W.S.Crohane


Ballybeggan Water Supply

Existing Pumping Plant

Flow rate 140 m3/hr

Head 107 m.

Motor eff. 91%

Pump eff. 56%

Overall 51%

System hydraulic power 41 kW

Power consumed from ESB 83 kW

New Pumping Plant

164 m3/hr

113 M.

93%

78%

72%

51 Kw

74 Kw

ANNUAL ENERGY COST €25,023 €14,330

New Pumping Plant Cost

Payback Period

€27,554

2.5 years


Ballybeggan


Monitoring and Targeting


Variable Speed


Motor Principles

• The speed of an induction motor is normally fixed because the electricity supply frequency is fixed, as is the number of poles in the motor.

• The speed ( ignoring slip ) is calculated from the formula :

Speed(rpm) = 120 X frequency (HZ) / no of motor poles

• i.e.: - a 2 pole motor on 50 Hz supply has a speed of 120 x 50 = 3000 rpm

• Equally a 2 pole motor on a 60 Hz supply has a speed of 3600 r/min

• Therefore, by varying the frequency the speed can also be varied.


Fan Affinity Laws(Applies to all centrifugal loads)

� Flow proportional to the speed

� Pressure proportional to the speed squared

� Power proportional to the speed cubed

Speed (%)

Input Power (%)100

0

80

60

40

20

010 20 30 40 50 60 70 80 90 100


Pumping Water

Variable Speed Flow Control

• The performance of a pump is directly related to its

speed in rpm, providing there is no cavitation. The law

of similarity may be used.

• For example, doubling the Pump Speed

• Flow x 2

• Head x 4

• Power consumed x 8


Speed Change Formulas






VSDMethods of control

There are two methods of control:

• Open Loop. The speed is simply controlled by a

potentiometer. The speed is set either by a person, or

perhaps by simple controls allowing perhaps 2-4

speeds, depending on the situation.

• Closed Loop. This is much more powerful, with the

user setting the flow, temperature, pressure, or

whatever else it is that they want to control. Using a

sensor, the VSD adjusts the speed automatically to

maintain this parameter. This will always give

optimum results, as long as it is set up properly!


Variable speed drive

control

• VSD allows you to vary the speed of a motor to match precisely the demands of a system.

• Control a booster pump to operate in a variable flow situation and still maintain a minimum pressure in a distribution main.

• Allows you to use full size impellers in pumps to get maximum efficiency.

• Unequal sized pumps can operate in parallel.

• Soft starting and stopping to minimize surges in water mains.

• Precise control of oxygen level in a waste water treatment plant.


Joint benefits of system

improvements

• Fitting a VSD not only saves energy, but also:– Reduced speed means less frictional wear, longer bearing and seal life.

– It reduces water hammer and resulting damage.

– Improved pressure control reduces leakage




Motor Efficiency


Motor Efficiency

Reservoir

Source

Motor (4)

Real

work

Done

Pipe

losses

Pump

losses

Motor

losses


The European Efficiency

Labeling Scheme (2002-2010)

2 pole

4 pole

% Efficiency

kW

1.1 90


IEC 1-4


Motors and Legislation

Commission Regulation (EC) No 640/2009 (Directive 2005/32/EC)

In detail:

– IE2 by June 16, 2011

– IE3 by January 1, 2015 (for motors >=7.5 to 375 kW) and IE2 only in combination with an adjustable speed drive

– IE3 for all motors by January 1, 2017, (for motors from 0.75 to 375 kW) and IE2 only in combination with an adjustable speed drive.



Repair Replace - HEM

Cost €1,233 €1,595

2 yr running cost €38,663 €37,622

Total cost €39,895 €39,217

The Real Cost of

Rewinding a Motor

HEMsaving - €679Original - 90.5%

Repair - 90.0%

HEM - 92.5%


Pipe Design


Suction/Inlet

Pipework Layout


Flow Velocities

• Suction pipes – 1 to 2 m/s

• Inlet pipes – 1.5 to 2.5 m/s

• Discharge pipes – 2 to 3 m/s

• The same velocities apply to

gate non-return and foot valves.


Pump Connections

• The right pipe size is a compromise between pipe cost and

excessive friction loss. Do the calculations and insure that the

pipe losses and velocities are at acceptable levels. Do not depend

on the size of the pump flanges, in most cases larger pipes and

valves are required. Use long radius bends and radial tees.

• A small pipe will initially cost less but the friction loss will be higher

and the pump energy cost will be greater. If you know the cost of

energy and the purchase and installation cost of the pipe you can

select the pipe diameter based on a comparison of the pipe cost

vs power consumption.


Control Systems


Flow Control by Throttling

• Changing the flow rate Q by operating a throttle valve

is the simplest flow control method not only for a

single adjustment of the flow rate but also for its

continuous control, since it requires the least

investment.

• But it is also the most energy wasting method, since

this method simply increases the head to reduce the

flow and thereby increases the energy consumed.


Reservoir Level Control

• Stop / Start

• PID

• Step Control

• Day / Night


Pressure Control

• Continuous Pumping.

• Control with 2 to 3 fixed speed pumps

• On /Off with Pressure Tank.

• Variable Speed Control – PID and Step

Control


Pump Protection

• Low Water Protection

• Loss of Prime - No-flow

• Burst Main

• High Pressure

• Bearing Over Heat


Motor Protection

• Over / Under current

• Overheat

• Voltage

• Power Factor

• Bearing Over Heat


Thank You!

Documents

4 - TEA Water Services - Pump Curves Final MFtea.ie/wp-content/uploads/2011/08/4-Water-Services-Pump-Curves.pdf · curve or the pump curve must be changed. ... • The performance