pumps and pumping systems ppt

8/12/2019 Pumps and Pumping Systems Ppt

1/40

1

Training Session on Energy

Equipment

Pumps & Pumping

Systems

Presentation from the

Energy Efficiency Guide for Industry in Asia

www.energyefficiencyasia.org

UNEP 2006


2/40

2

UNEP 2006

Training Agenda: Pumps

Introduction

Type of pumps

Assessment of pumps

Energy efficiency opportunities


3/40

3

UNEP 2006

Introduction

20% of worlds electrical energy

demand

25-50% of energy usage in some

industries

Used for Domestic, commercial, industrial and

agricultural services

Municipal water and wastewater services

What are Pumping Systems


4/40

4

UNEP 2006

Introduction

Objective of pumping system


(US DOE, 2001)

Transfer liquid

from source to

destination

Circulate liquid

around a system


5/40

5

UNEP 2006

Introduction

Main pump components

Pumps Prime movers: electric motors, diesel engines,

air system

Piping to carry fluid

Valves to control flow in system Other fittings, control, instrumentation

End-use equipment

Heat exchangers, tanks, hydraulic machines



6/40

6

UNEP 2006

Introduction

Head

Resistance of the system

Two types: static and friction

Static head

Difference in height betweensource and destination

Independent of flow

Pumping System Characteristics

destination

source

Stati

chead

Static

head

Flow


7/40

7

UNEP 2006

Introduction

Static head consists of

Static suction head (hS): lifting liquid relative topump center line

Static discharge head (hD) vertical distance

between centerline and liquid surface in

destination tank

Static head at certain pressure


Head (in feet) = Pressure (psi) X 2.31

Specific gravity


8/40

8

UNEP 2006

Introduction

Friction head

Resistance to flow in pipe and fittings Depends on size, pipes, pipe fittings, flow

rate, nature of liquid

Proportional to square of flow rate

Closed loop systemonly has friction head

(no static head)


Friction

head

Flow


9/40

9

UNEP 2006

Introduction

In most cases:

Total head = Static head + friction head


Systemhead

Flow

Static head

Friction

head

System

curve

Systemhead

Flow

Static head

Friction

head

System

curve


10/40

10

UNEP 2006

Introduction

Pump performance curve

Relationship betweenhead and flow

Flow increase

System resistance increases

Head increases Flow decreases to zero

Zero flow rate: risk ofpump burnout


Head

Flow

Performance curve for

centrifugal pump


11/40

11

UNEP 2006

Introduction

Pump operating point


Duty point: rate

of flow at certain

head

Pump operating

point:

intersection of

pump curve and

system curveFlow

Head

Static

head

Pump performance

curve

System

curve

Pump

operating

point


12/40

12

UNEP 2006

Introduction

Pump suction performance (NPSH)

Cavitation or vaporization: bubbles inside pump

If vapor bubbles collapse

Erosion of vane surfaces

Increased noise and vibration

Choking of impeller passages

Net Positive Suction Head

NPSH Available: how much pump suction

exceeds liquid vapor pressure

NPSH Required: pump suction needed to avoidcavitation



13/40

13

UNEP 2006


Introduction

Type of pumps

Assessment of pumps



14/40

14

UNEP 2006

Type of Pumps

Classified by operating principle

Pump Classification

DynamicPositive

Displacement

Centrifugal Special effect Rotary Reciprocating

Internal

gear

External

gear

LobeSlide

vane

Others (e.g.Impulse, Buoyancy)

Pumps

DynamicPositive

Displacement

Centrifugal Special effect Rotary Reciprocating

Internal

gear

External

gear

LobeSlide

vane

Others (e.g.Impulse, Buoyancy)

Pumps


15/40

15

UNEP 2006

Type of Pumps

Positive Displacement Pumps

For each pump revolution

Fixed amount of liquid taken from one end

Positively discharged at other end

If pipe blocked

Pressure rises Can damage pump

Used for pumping fluids other than

water


16/40

16

UNEP 2006

Type of Pumps

Positive Displacement Pumps

Reciprocating pump

Displacement by reciprocation of pistonplunger

Used only for viscous fluids and oil wells

Rotary pump

Displacement by rotary action of gear, cam

or vanes

Several sub-types

Used for special services in industry


17/40

17

UNEP 2006

Type of Pumps

Dynamic pumps

Mode of operation

Rotating impeller converts kinetic energyinto pressure or velocity to pump the fluid

Two types

Centrifugal pumps: pumping water in

industry75% of pumps installed

Special effect pumps: specialized conditions


18/40

18

UNEP 2006

Type of Pumps

Centrifugal Pumps

How do they work?

(Sahdev M)

Liquid forced intoimpeller

Vanes pass kinetic

energy to liquid: liquid

rotates and leaves

impeller

Volute casing converts

kinetic energy into

pressure energy


19/40

19

UNEP 2006

Type of Pumps

Centrifugal Pumps

Rotating and stationary components

(Sahdev)


20/40

20

UNEP 2006

Type of Pumps

Centrifugal Pumps

Impeller Sahdev)

Main rotating part that provides centrifugal

acceleration to the fluid

Number of impellers = number of pump stages

Impeller classification: direction of flow, suction type

and shape/mechanical construction

Shaft

Transfers torque from motor to impeller during pump

start up and operation


21/40

21

UNEP 2006

Type of Pumps

Centrifugal Pumps

Casings

Volute Casing (Sahdev) Functions

Enclose impeller as pressure vessel Support and bearing for shaft and impeller

Volute case

Impellers inside casings Balances hydraulic pressure on pump shaft

Circular casing

Vanes surrounds impeller

Used for multi-stage pumps


22/40

22

UNEP 2006


Introduction

Type of pumps

Assessment of pumps



23/40

23

Assessment of pumps

Pump shaft power (Ps) is actual horsepower

delivered to the pump shaft

Pump output/Hydraulic/Water horsepower (Hp) is

the liquid horsepower delivered by the pump

How to Calculate Pump Performance

Hydraulic power (Hp):

Hp = Q (m3/s) x Total head, hd - hs (m) x (kg/m3) x g (m/s2) / 1000

Pump shaft power (Ps):

Ps = Hydraulic power Hp / pump efficiency Pump

Pump Efficiency (Pump):

Pump = Hydraulic Power / Pump Shaft Power

UNEP 2006hd - discharge head hssuction head, - density of the fluid gacceleration due to gravity


24/40

24

UNEP 2006

Assessment of pumps

Absence of pump specification data

to assess pump performance Difficulties in flow measurement and

flows are often estimated

Improper calibration of pressuregauges & measuring instruments

Calibration not always carried out

Correction factors used

Difficulties in Pump Assessment


25/40

25

UNEP 2006


Introduction

Type of pumps

Assessment of pumps



26/40

26

UNEP 2006

Energy Efficiency Opportunities

1. Selecting the right pump

2. Controlling the flow rate by speed

variation

3. Pumps in parallel to meet varying

demand

4. Eliminating flow control valve

5. Eliminating by-pass control

6. Start/stop control of pump

7. Impeller trimming


27/40

27

UNEP 2006


1. Selecting the Right Pump

Pump performance curve for centrifugal

pump

BEE India,

2004


28/40

28

UNEP 2006


1. Selecting the Right Pump

Oversized pump

Requires flow control (throttle valve or by-

pass line) Provides additional head

System curve shifts to left

Pump efficiency is reduced

Solutions if pump already purchased

VSDs or two-speed drives

Lower RPM

Smaller or trimmed impeller


29/40

29

UNEP 2006


2. Controlling Flow: speed variation

Explaining the effect of speed

Affinity laws: relation speed N and Flow rate Q N

Head H N2

Power P N3

Small speed reduction (e.g. ) = large

power reduction (e.g. 1/8)


30/40

30

UNEP 2006


Variable Speed Drives (VSD)

Speed adjustment over continuous

range

Power consumption also reduced!

Two types

Mechanical: hydraulic clutches, fluid couplings,

adjustable belts and pulleys

Electrical: eddy current clutches, wound-rotor

motor controllers, Variable Frequency Drives

(VFDs)



31/40

31

UNEP 2006


Benefits of VSDs

Energy savings (no t just reduced f low !)

Improved process control

Improved system reliability

Reduced capital and maintenance

costs

Soft starter capability



32/40

32

UNEP 2006


3. Parallel Pumps for Varying Demand

Multiple pumps: some turned off during low

demand

Used when static head is >50% of total head

System curve

does not change

Flow rate lowerthan sum of

individual

flow rates

(BPMA)


33/40

33

UNEP 2006


4. Eliminating Flow Control Valve

Closing/opening discharge valve (throttling)

to reduce flow

Head increases:

does not reduce

power use

Vibration andcorrosion: high

maintenance

costs and reduced

pump lifetime

(BPMA)


34/40

34

UNEP 2006


5. Eliminating By-pass Control

Pump discharge divided into two

flows One pipeline delivers fluid to destination

Second pipeline returns fluid to the source

Energy wastage because part of fluidpumped around for no reason


35/40

35

UNEP 2006


6. Start / Stop Control of Pump

Stop the pump when not needed

Example:

Filling of storage tank

Controllers in tank to start/stop

Suitable if not done too frequently

Method to lower the maximum

demand (pumping at non-peak hours)


36/40

36

UNEP 2006


7. Impeller Trimming

Changing diameter: change in

velocity Considerations

Cannot be used with varying flows

No trimming >25% of impeller size

Impeller trimming same on all sides

Changing impeller is better option but more

expensive and not always possible


37/40


38/40

38

UNEP 2006


Comparing Energy Efficiency

Options

Parameter Changecontrol valve

Trim impeller VFD

Impeller

diameter

430 mm 375 mm 430 mm

Pump head 71.7 m 42 m 34.5 m

Pump efficiency 75.1% 72.1% 77%

Rate of flow 80 m3/hr 80 m3/hr 80 m3/hr

Power

consumed

23.1 kW 14 kW 11.6 kW


39/40

39

Training Session on Energy

Equipment

Pumps & Pumping

Systems

THANK YOU

FOR YOUR ATTENTION

UNEP 2006


40/40

40

Disclaimer and References

This PowerPoint training session was prepared as part ofthe project Greenhouse Gas Emission Reduction from

Industry in Asia and the Pacific (GERIAP). While

reasonable efforts have been made to ensure that the

contents of th is publication are factually correct and

proper ly referenced, UNEP does not accept responsibil i ty for

the accuracy or completeness of the contents, and shal l not

be l iable for any loss or damage that may be occasioned

directly or indirectly through the use of, or rel iance on, the

contents of this publication. UNEP, 2006. The GERIAP project was funded by the Swedish

I nternational Development Cooperation Agency (Sida)

Ful l references are included in the textbook chapter that is

pumps and pumping systems ppt

Documents