23407078 compressors

8/6/2019 23407078 Compressors

1/35

1

Training Session on EnergyTraining Session on Energy

EquipmentEquipment

Compressors &Compressors &

Compressed AirCompressed Air

SystemsSystemsPresentation from the

Energy Efficiency Guide for Industry in Asia

www.energyefficiencyasia.org

UNEP 2006 UNEP 2006

8/6/2019 23407078 Compressors

2/35

2

UNEP 2006 UNEP 2006

Training Agenda: CompressorTraining Agenda: Compressor

Introduction

Types of compressors

Assessment of compressors and

compressed air systems

Energy efficiency opportunities

8/6/2019 23407078 Compressors

3/35

3

UNEP 2006 UNEP 2006

Compressors: 5 to > 50,000 hp

70 90% of compressed air is lost

Significant Inefficiencies

IntroductionIntroduction

(McKane and Medaris, 2003)

8/6/2019 23407078 Compressors

4/35

4

UNEP 2006 UNEP 2006(eCompressedAir)

Electricity savings: 20 50%

Maintenance reduced, downtime decreased,production increased and product quality

improved

Benefits of managed system


8/6/2019 23407078 Compressors

5/35

5

UNEP 2006 UNEP 2006

Intake air filters

Inter-stage coolers

After coolers

Air dryers

Moisture drain traps

Receivers

Main Components in Compressed

Air Systems


8/6/2019 23407078 Compressors

6/35

6

UNEP 2006 UNEP 2006


Introduction





8/6/2019 23407078 Compressors

7/35

7

UNEP 2006 UNEP 2006

Two Basic Compressor Types

Types of CompressorsTypes of Compressors

Type ofcompressor

Positive

displacementDynamic

Reciprocating Rotary Centrifugal Axial

8/6/2019 23407078 Compressors

8/35

8

UNEP 2006 UNEP 2006(King, Julie)

Used for air and refrigerant compression

Works like a bicycle pump: cylinder volume reduces

while pressure increases, with pulsating output

Many configurations available

Single acting when using one side of the piston, and

double acting when using both sides

Reciprocating Compressor


8/6/2019 23407078 Compressors

9/35

9

UNEP 2006 UNEP 2006

Screw compressor

Rotors instead of pistons: continuous

discharge

Benefits: low cost, compact, low weight,

easy to maintain

Sizes between 30 200 hp

Types

Lobe compressor

Screw compressor

Rotary vane / Slide vane

Rotary Compressor


8/6/2019 23407078 Compressors

10/35

10

UNEP 2006 UNEP 2006(King, Julie)

Rotating impeller

transfers energyto move air

Continuous duty

Centrifugal Compressor


Designed oil

free

High volume

applications

> 12,000 cfm

8/6/2019 23407078 Compressors

11/35

11

UNEP 2006 UNEP 2006

Efficiency at full, partial and no load

Noise level

Size

Oil carry-over

Vibration

Maintenance

Capacity

Pressure

Comparison of Compressors


8/6/2019 23407078 Compressors

12/35

8/6/2019 23407078 Compressors

13/35

13

UNEP 2006 UNEP 2006

Capacity: full rated volume of flow of

compressed gas

Actual flow rate: free air delivery (FAD)

FAD reduced by ageing, poor maintenance,

fouled heat exchanger and altitude Energy loss: percentage deviation of FAD

capacity

Capacity of a Compressor

Assessment of CompressorsAssessment of Compressors

8/6/2019 23407078 Compressors

14/35

14

UNEP 2006 UNEP 2006

Isolate compressor and receiver and close receiver

outlet

Empty the receiver and the pipeline from water

Start the compressor and activate the stopwatch

Note time taken to attain the normal operational

pressure P2 (in the receiver) from initial pressure P1

Calculate the capacity FAD:

Simple Capacity Assessment Method


P2 = Final pressure after filling (kg/cm2a)

P1 = Initial pressure (kg/cm2a) after bleeding)

P0 = Atmospheric pressure (kg/cm2a)

V = Storage volume in m3 which includes receiver,

after cooler and delivery piping

T = Time take to build up pressure to P2 in minutes

8/6/2019 23407078 Compressors

15/35

15

UNEP 2006 UNEP 2006

Compressor Efficiency


Most practical: specific power

consumption (kW / volume flow rate)

Other methods

Isothermal

Volumetric

Adiabatic

Mechanical

8/6/2019 23407078 Compressors

16/35

16

UNEP 2006 UNEP 2006

Isothermal efficiency

P1 = Absolute intake pressure kg / cm2

Q1 = Free air delivered m3 / hr

r = Pressure ratio P2/P1



Isothermal efficiency =

Actual measured input power / Isothermal power

Isothermal power (kW) = P1 x Q1 x loger / 36.7

8/6/2019 23407078 Compressors

17/35

17

UNEP 2006 UNEP 2006

Volumetric efficiency

D = Cylinder bore, meter

L = Cylinder stroke, meter

S = Compressor speed rpm

= 1 for single acting and 2 for double acting cylinders

n = No. of cylinders



Volumetric efficiency

= Free air delivered m3/min / Compressor displacement

Compressor displacement = x D2/4 x L x S x x n

8/6/2019 23407078 Compressors

18/35

18

UNEP 2006 UNEP 2006

Consequences

Energy waste: 20 30% of output

Drop in system pressure

Shorter equipment life

Common leakage areas

Couplings, hoses, tubes, fittings

Pressure regulators

Open condensate traps, shut-off valves

Pipe joints, disconnects, thread sealants

Leaks


8/6/2019 23407078 Compressors

19/35

19

UNEP 2006 UNEP 2006

Total leakage calculation:

T = on-load time (minutes)

t = off-load time (minutes)

Well maintained system: less than 10%

leakages

Leak Quantification Method


Leakage (%) = [(T x 100) / (T + t)]

8/6/2019 23407078 Compressors

20/35

20

UNEP 2006 UNEP 2006

Shut off compressed air operated equipments

Run compressor to charge the system to setpressure of operation

Note the time taken for Load and Unload

cycles

Calculate quantity of leakage (previous slide) If Q is actual free air supplied during trial

(m3/min), then:

Quantifying leaks on the shop floor


System leakage (m3/minute) = Q T / (T + t)

8/6/2019 23407078 Compressors

21/35

21

UNEP 2006 UNEP 2006

Compressor capacity (m3/minute) = 35

Cut in pressure, kg/cm2 = 6.8

Cut out pressure, kg/cm2 = 7.5

Load kW drawn = 188 kW

Unload kW drawn = 54 kW

Average Load time =1.5 min

Average Unload time = 10.5 min

Example


Leakage = [(1.5)/(1.5+10.5)] x 35 = 4.375 m3/minute

8/6/2019 23407078 Compressors

22/35

22

UNEP 2006 UNEP 2006


Introduction





8/6/2019 23407078 Compressors

23/35

23

UNEP 2006 UNEP 2006

Significant influence on energy use

Energy Efficiency OpportunitiesEnergy Efficiency Opportunities

1. Location

2. Elevation

Higher altitude = lower volumetric

efficiency

8/6/2019 23407078 Compressors

24/35

24

UNEP 2006 UNEP 2006

3. Air Intake

Keep intake air free from contaminants,

dust or moist

Keep intake air temperature low

Every 4 oC rise in inlet air temperature = 1%

higher energy consumption

Keep ambient temperature low when

an intake air filter is located at the

compressor


8/6/2019 23407078 Compressors

25/35

25

UNEP 2006 UNEP 2006

4. Pressure Drops in Air Filter

Install filter in cool location or draw

air from cool location

Keep pressure drop across intake air

filter to a minimum

Every 250 mm WC pressure drop =2% higher energy consumption


8/6/2019 23407078 Compressors

26/35

26

UNEP 2006 UNEP 2006

5. Use Inter and After Coolers

Inlet air temperature rises at each

stage of multi-stage machine Inter coolers: heat exchangers that

remove heat between stages

After coolers: reduce air temperatureafter final stage

Use water at lower temperature:

reduce power


8/6/2019 23407078 Compressors

27/35

27

UNEP 2006 UNEP 2006

Higher pressure

More power by compressors

Lower volumetric efficiency

Operating above operating pressures

Waste of energy

Excessive wear


6. Pressure Settings

8/6/2019 23407078 Compressors

28/35

28

UNEP 2006 UNEP 2006

a. Reducing delivery pressure

Operating a compressor at 120 PSIG instead of 100

PSIG: 10% less energy and reduced leakage rate



b. Compressor modulation by optimum

pressure settings

Applicable when different compressors connected

c. Segregating high/low pressure

requirements

Pressure reducing valves no longer needed

8/6/2019 23407078 Compressors

29/35

8/6/2019 23407078 Compressors

30/35

30

UNEP 2006 UNEP 2006

d. Design for minimum pressure drop in

the distribution line



Typical pressure drop in compressed air line for

different pipe size (Confederation of Indian Industries)

8/6/2019 23407078 Compressors

31/35

31

UNEP 2006 UNEP 2006

7. Minimizing Leakage

Use ultrasonic acoustic detector

Tighten joints and connections

Replace faulty equipment

8. Condensate Removal

Condensate formed as after-cooler reduces

discharge air temperature

Install condensate separator trap to remove

condensate


8/6/2019 23407078 Compressors

32/35

32

UNEP 2006 UNEP 2006

9. Controlled usage

Do not use for low-pressure

applications: agitation, combustion air,pneumatic conveying

Use blowers instead

10. Compressor controls

Automatically turns off compressor

when not needed


8/6/2019 23407078 Compressors

33/35

33

UNEP 2006 UNEP 2006

9. Maintenance Practices

Lubrication: Checked regularly

Air filters: Replaced regularly

Condensate traps: Ensure drainage

Air dryers: Inspect and replace filters


8/6/2019 23407078 Compressors

34/35

34

Training Session on EnergyTraining Session on Energy

EquipmentEquipment

Compressors &Compressors &

Compressed AirCompressed AirSystemsSystems

THANK YOU FOR YOUR ATTENTIONTHANK YOU FOR YOUR ATTENTION

UNEP GERIAP UNEP GERIAP

8/6/2019 23407078 Compressors

35/35

35

UNEP 2006 UNEP 2006

Disclaimer and ReferencesDisclaimer and References

This PowerPoint training session was prepared as part of

the 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 this publication are factually correct andproperly referenced, UNEP does not accept responsibility for

the accuracy or completeness of the contents, and shall not

be liable for any loss or damage that may be occasioned

directly or indirectly through the use of, or reliance on, the

contents of this publication. UNEP, 2006.

The GERIAP project was funded by the Swedish

International Development Cooperation Agency (Sida)

Full references are included in the textbook chapter that is

available on www.energyefficiencyasia.org

23407078 compressors

Documents