Compressed Air a+

หลักการเบื้องตนของระบบ

อัดอากาศ

Proportional relationship between pressure, temperature and volume: still valid:

Compressed air is ...... compressed atmospheric air... a mixture of gases... compressible... an energy carrier

userair main

air treatmentAir centre

Power stationgrid system

transformeruserWhat is compressed

air?

1. Training Course in Compressed Air Technology1. Training Course in Compressed Air Technology

...is generated by the weightof the atmosphere. It is dependent on the DENSITYof the air and the height:

The normal atmospheric pressure at sea level is 1.013 bar (760 mmHg (Torr))

Atmospheric pressure...


atmospheric pressure

vacuum100%

0%

pamb

Absolute pressure ...

... is the pressure measuredfrom absolute zero.It is used for all theoreticalapproaches and is required invacuum and blower techniques.

Gauge pressure ...

... is the practical reference pressureand is based on atmospheric pressure.


absolute pressure

gauge pressurevacuum

(g) (g) (g) (g)

Pg

Physical lawsCOMPRESSED AIR is atmospheric air under pressure. That means energy is stored in the air. When the compressed air expands againthis energy is released as WORK.

pressure (energy)

EXPANSION

WORK


Generally:Equivalents

105 Pa = 1 bar

1 MPa = 10 bar

Gauge pressure1 bar = 14,5 psi(g)

1 hPa = 0,001 bar

1 bar = 10197 mmWC

1 bar = 750,062 Torr

Dimensions:

A = 1 m2

1 Pascal (Pa) =1 Newton (N)

1 m² (A)

1 N

Pressure (p) = Force (F)Area (A)

Definition of pressures


Basic units m = Meter

s = Second

K = Kelvin

kg = Kilogram

A = Ampere

mol = Molar mass

Derived units N = Newton

bar = Bar

J = Joule

C = Celsius

Pa = Pascal

Ω = Ohm

W = Watt

Hz = Hertz


If the volume is reduced under constant temperature,the pressure increases.

Heat dissipation

Natural lawsIsotherms (constant temperature)

p0 x V0 = p1 x V1 = constant


Heat dissipation

V

p

p1

p0

V1 V0dV

T0 = T1

1

0

Isotherms (constant temperature)


Gas law relating to a closed system:

p0 x V0 p1 x V1

T0 T1= = R = constant

p = pressure (bar (absolute))V = volume (m3)T = temperature (K)R = special gas constants

e.g. R = 28.96 = 289.6

for dry air

bar·m³K

Jkg·K

Gas equation


nitrogen78%

oxygen21%

other gasses1%

Components of air


7 m³atmospheric

air volume

ambient air pressure1 bar (a)

working pressure7 bar (a) = 6 bar (g)

1 working m³

Volume


The volume of atmospheric air decreases at an inverse ratio to the respective absolute pressures (at constant temperature,without taking humidity into account)

Ambient air pressure p0, V0

Working pressure7 bar (a)= 6 bar (g)

Expansion:

Workingpressurep1, V1

Volume


pp

Flow velocity in air lines

V = flow volumev = velocityA = pipe sectional area

V = A1 x v1 = A2 x v2 • A1

A2

v2

v1=

•

A1v1

A2v2

valid is:


Flow profilepipe wall

border layer

flow velocity


Flow typesWe differentiate between:laminar (even) and turbulent (swirling) flow


อุปกรณหลักในระบบอัดอากาศ หลักการใชงาน

และการบํารุงรักษา 1.Air Compressors

Compressed Air Generation

ejector centrifugal-turbo

axial-turbo

vane liquidring

screw rotaryblower

labyrinth diaphragm

rotary reciprocating

trunk crosshead free-piston

single-rotor double-rotor

helical

displacementcompressor

dynamic compressor

Compressor types


Screw compressors

fluid with heat of compression

thermostaticvalve

fluid filter

hot fluid

compressedair

fluid-air mixture

cooled fluid

Construction:


1st stage,centrifugal

2nd stage, separatorelementa) coarse filter

layerb) fine filter

layer

Fluid separation:


และการบํารุงรักษา

2. Air Dryer

1. Air inlet2. Air to air heat exchanger3. Refrigerant to air heat exchanger4. Refrigerant compressor5. Condensate separation,

automatic condensate drain6. Compressed air outlet

Refrigeration drying

Air Treatment



3. Filter

Streamed from the inside to the outside.Used as a liquid filter

Principle the same as all deep-bed filters

Prefilter

used as a coarse filter for 100% saturated compressed air (or for water vapour components in the liquid phase)

Air Treatment

Streamed from the inside to the outside. Used as a deep-bed filter

Microfilter

0.01 to 0.001 micronfor liquids(aerosols) and particles

Air Treatment

contaminated air filter medium (deep-bed filter) technically oil-free clean air

Direct interception

Impact

Diffusion /Coalescence

How does the microfilter work?Air Treatment



4. Drain

condensate collection

cyclonicair movement

deflector

air outletair inletCondensate separation

To ensure sufficient separation,liquids and heavy particles are

subjected to centrifugal forces athigh rates of flow.

The degree of separation is around 95% at 6 bar, 20 °C and the nominalvolumetric flow rate. The pressure

drop is approximately 0.05 bar .

Air Treatment

compressedair outlet

pipework falling atapprox. 2 ‰condensate

collector

condensatedrain

Condensate separation

The compressed air discharged from the aftercooler of a compressor is normally

saturated with water vapour to 100%. If the temperature of the compressed air

falls, the water vapour condenses.

A coarse separation of the condensate can be achieved if the pipework and the compressed air outlets are installed as

shown in the illustration.

Air Treatment

• used directly at the takeoff point• mechanical filter

• rotating movement• deflection plate

• condensate drain (important!)

Condensate separationFine filter

Air Treatment

Drainage occurs only when sufficient condensate has collected

No compressed air blowoff

Regular maintenance required

condensate inlet

air back flow line connection

manual valvecondensate

outlet

Condensate drains: float type

Air Treatment

• automatic and regular drainage• 230 V / 50 Hz

• interval 1.5 to 30 min• opening period 0.4 to 10 sec

• condensate can be directed into a disposal canister

1

3

2

1 ball valve2 dirt trap

3 solenoid valve withintegrated or external

timer

Condensate drains: solenoid valve, timer controlled

Air Treatment

Capacitive level sensingAutomatic pressure matching

Self-monitoringVolt-free alarm contact

Condensate drains: Electronic level-sensingtype (Eco-Drain)

2 collection chamber9 discharge pipe6 level sensor8 valve seat

1 condensate inlet 4 solenoid valve2 collection chamber5 valve

diaphragm3 pressure balance line

Air Treatment

การประหยัดพลงังานในระบบอัด

อากาศ

1. การออกแบบระบบ และ เลือกใชงาน

Parallel Line Diagram

Series Lind Diagram

Optimal design and installation

การประหยัดพลังงานในระบบอัดอากาศ

2. การหาปริมาณลมที่ตองการ ตามชนิดของโหลด

Ø

Air consumption chart for pneumatic cylinders

Working pressure in bar

Air consumption per cylinder stroke in litres/cm

Table air consumption for pneumatic cylindersTable air consumption for pneumatic cylinders

Air consumption of pneumatic equipmentexamples:

Paint spray gunswater colours andthin cellulos paintø 0.5 mmNitro and thinsynthetic resinsø 1.5 mmø 1.8 mm

Thick nitro andnormal syntheticresins ø 2.0 mm

ø

Lime-water colour,compound filling guns ø 3.0 mmBlow gunø 1 / 1.5 / 2 mmSpray gun

Equipment, type Working pressure

bar (g)Air consumptionl/min m³/h

Nozzle

flat round flat round

451.0

2.53.5

4.5

5.0

6.03.0

150215

270

320

60/135/240 4/8/14

35

110160

180

230

3

913

16

19

2

710

11

14

65 4

Example: spray gun

Working periods of the toolper hour

Standstill periods of the toolper hour

Overall working period per hour: 25 min

overall working period 25 minUtilisation factor = =

reference period 60 min

Utilisation factor of the spray gun is approx. 40%

Determining the utilisation factor

3. Sizing a compressor3. Sizing a compressor

10 20 30 40 50 60 70 80 90 100 150 20000

00

500 1000 1500 2000 2500 3000 3500 4000

1

2

3

4

5

6

7

2 3 4 5 6

8

10

Nozzle diameter (mm)

Air volume

l/min

m³/h

Gau

ge p

ress

ure

(bar

)


Air consumption of free-jet nozzles

Nozzlediameter

( mm)

0.51.01.52.03.04.05.06.08.0

10.0

2

83055100225

410 330640 510900 7201250 10001950 1570

4

124590

170375

700 5501050 8501520 12202700 21504230 3400

6

1565125240520

980 7801500 12002120 17003770 30005900 4700

8

2085160310675

12501870275048007500

10

2510520038082515002300335058509200

Gauge working pressure ( bar )

Air consumption of nozzles (l / min)

The lower values are valid for sandblasting!


The optimum duty-cycleof a reciprocating compressor-is 70 %.The required air delivery is:

334+33+50+66 l/min0.7

The required reciprocating compressor must have a freeair delivery of at least 690 l/minat a gauge pressure of 8 bar.

The model selected is:K 1200-500, max. gauge working pressure 10 bar, 865 l/min free air delivery at 8 bar gauge pressure and7.5 kW rated motor power.

Total demand = 150 + 80 + 24 + 80 = 334 l/minThe following must be addedfor leakagesfor errorsas a reserve

+ 10 % = 33 l/min+ 15 % = 50 l/min+ 20 % = 66 l/min

Sizing a reciprocal compressor

7. Sizing a compressor

= 690 l/min

Air demandWorkingpressure (g)

NumberUtilisationfactor

Effectiveair demand

Paint spray-gunØ 1.5 mmflat jet

Paint spray-gunØ 3 mmflat jet

Blow-gunØ 2 mm

Screw-driver

150 l/min 320 l/min 240 l/min 400 l/min

2.5 bar 5 bar 6 bar 6 bar

2 1 1 1

50 % 25 % 10 % 20 %2 x 150 x 0.5

150 l/min320 x 0.2580 l/min

240 x 0.124 l/min

400 x 0.280 l/min

Workingspecification

Total demand = 150 + 80 + 24 + 80 = 334 l/minThe following must be added:for leakagesfor errorsas a reserve

+ 10 % = 33 l/min+ 15 % = 50 l/min+ 20 % = 66 l/min

The optimum duty cycle of ascrew compressor is 100 %.The required air delivery is:

The required screw compressor must have a free air delivery of at least 483 l/min at a gaugepressure of 7.5 bar.

The model selected is:Aircenter 6 (SX6-TA5-280), working pressure max. 7.5 bar,583 l/min free air deliveryat 7.5 bar gauge pressure and4 kW rated motor power.

Sizing a screw compressor

( 334+33+50+66 l/min )

7. Sizing a compressor

= 483 l/min

Air demandWorkingpressure (g)

NumberUtilisationfactor

Effectiveair demand

Paint spray-gunØ 1.5 mmflat jet

Paint spray-gunØ 3 mmflat jet

Blow-gunØ 2 mm

Screw-driver

150 l/min 320 l/min 240 l/min 400 l/min

2.5 bar 5 bar 6 bar 6 bar

2 1 1 1

50 % 25 % 10 % 20 %2 x 150 x 0.5

150 l/min320 x 0.2580 l/min

240 x 0.124 l/min

400 x 0.280 l/min

Workingspecification

ขอสรุปสําหรับการปรับปรุงระบบลมอดัเพื่อการลดพลังงาน

ปรับปรุงโดยไมมีการลงทุน

1. การลดแรงดันลมจากตนทาง(หองปมลม)

2. การจัดใหปมลมทาํงานใหเหมาะสมกับปรมิาณความตองการของเครื่องจักร3. การลดแรงดันลมเทาที่เครื่องจักรตองการดวย regulator4. การเปลี่ยนอะไหลสิ้นเปลอืงในระยะกําหนดเวลาใชงาน 5. การเลือก main line filter สําหรับคุณภาพลมอัดตามที่เครื่องจักร

ตองการ 6. การควบคุมการใชลมใหเหมาะสม เชน ใชลมเปาตัวทําความสะอาด,ใชลมเปา

ตัวแทนพัดลม และใชลมเปาชิ้นงานแทนระบบสปรงิหรือตัวเกี่ยวออก7. การตรวจเช็คประสิทธิภาพของปมลมอยางสม่ําเสมอทุกป8. เลือก mode การควบคุมปมลมใหเหมาะสมกับลักษณะของ load

(Dual control,Quandro control,Modulation control)

ปรับปรุงโดยมกีารลงทุน

1. เปลี่ยนปมลมทีม่ีประสิทธภิาพต่ําดวยปมลมทีม่ีประสิทธภิาพสูงกวา

2. ใชระบบควบคุมกลางในกรณีที่มีปมลมหลายตัว

3. ใชปมลมทีส่ามารถควบคุมความเร็วรอบไดในกรณ ีload demand มีการ

เปลี่ยนแปลงมากๆ หรือแบงปมลมสําหรับ peak load เปนหลายตัวแทนตัวใหญ ตัวเดียว

4. เปลี่ยนชุด auto-drain เปนแบบที่ไมมีการสูญสียลมขณะ drain น้ํา

5. ซื้อลมในราคา fix unit จากผูผลิตลมเพื่อจําหนาย

6. การตรวจหาและลดปรมิาณลมรัว่

7. การตรวจสอบขนาดทอทางเดินลมไมใหมี pressure drop สูงเกินมาตรฐาน

8. การปรบัปรงุระบบระบายความรอนในหองปมลม

9. การเลือกชนิดของair dryer ใหเหมาะสมกับ process

10. การนําลมระบายความรอนจากปมลมไปใชใหเกิดประโยชน

11. ใชขนาดถงัลมใหเหมาะสมกับขนาดของปมลม และปรมิาณการใชลมของโรงงาน

Minimum diameters of pipes

FADm3/min

working pressure 7.5 bar (g)

length of pipelineup to 50 m up to 100 m up to 200 m over 200 m

see straight-line graph

up to 0.5up to 1,0up to 1.5up to 2.0up to 3.0up to 5.0

3/4"1"1"

1 1/4"1 1/4"1 1/2"

1"1"

1 1/4"1 1/2"1 1/2"

2"

1 1/4"1 1/4"1 1/2”

2"2"

up to 7.5 1 1/2" 2 1/2" 2 1/2"

The Air MainThe Air Main

2"

Minimum diameters of pipes

FADm3/min

working pressure 7.5 bar (g)

length of pipelineup to 50 m up to 100 m up to 200 m over 200 m

see straight-line graph

up to 12.5up to 15,0up to 17.5up to 20.0up to 25.0up to 30.0

2 1/2"2 1/2"2 1/2"

3"3"3"

2 1/2"2 1/2"

3"3"

DN100DN100

3"3"

DN100DN100DN100DN100

up to 40.0 DN100 DN100 DN 125


Straight-line graphfor determining insidepipe diameter (steps 1 to 8)

1

2

3

4

5

67 8

Pipe length in m

Free air deliverym³/h - m³/min

Insidepipe dia. (mm)

System-pressurebar (g)

Pressure lossesbar


Trace leaksTrace leaks• soap connections

• locate source of noise• leakage spray

• ultra-sound device

Example:hole diameter: 3 mm

air loss: 0.5 m3/min (6 bar gauge)0.5 m3/min x 60 min/h = 30 m3/h

30 m3/h x 8000 h/year = 240,000 m3/year

240,000 m3/year x 0.33 Baht/m3 = 79,200 Baht/year


Max. pressure= required working pressure of the users+ sum of all losses (air main, air treatment devices)+ switching differential for compressor control

switching differential:ON = 7 bar (g)OFF = 7.5 bar (g)

screw compressordryer

Determining the highest pressure of an air centre

Pressure Setting.

p (bar)

Switching points offour equally sized units.All units can beinterchanged via the MAC 41

p too low alarm

Unit 1

2

3

4

Switching Points (first example)Cascade control

pmax

pmin

idlestop

full load

20406080

100

mot

or p

ower

in %

time

pres

sure

A B C D E

t1

t2

Dual ControlFull load - idle - stop operating mode

Types of compressor controlTypes of compressor control

Quadro ControlFull load - idle - stop with automaticselection of optimum operating mode

t5 t6

A B C D E F GH I K L M N OP Q R S T U V W

t3

t3

t8

t1

t2

t1

t4

t3

t1

t7

pmax

pmin

idlestop

full load

20406080

100

mot

or p

ower

in %

time

pres

sure


Dual Control (CP)Constant pressure, continuous delivery modeusing a proportional controller

A B C D E F G H I K L

t1

t3t2 t1

pR

pmax

pmin

idlestop

full load

20406080

100

mot

or p

ower

in %

time

pres

sure


inlet temperatureT1

inlet pressure p1

inlet humidity Frel1

dischargetemperature T2

dischargepressure p2

discharge volume V2

Power consumption in kW

Measurement of free air delivery

Package

Economic Appraisal

internal motor losses,accounted for in themotor efficiency

Motor shaft output power:mechanical forcein kW that the motor transmits into the shaft

Drive losses of thecooling fan Transmission losses of

belts/gearing

Compressor shaft power:required mechanicalforce in kW at thedrive shaft Rated motor power:

mechanical shaft powerin kW that the motor cansupply at 100% load.Quoted on the nameplate

Overallelectricalpowerconsumption

Electrical power consumption offan motor, if separate fan is fitted

0 0 0

Flow of force and power

kWh

Economic Appraisal

5000

5,5

6,0

6,5

airend 1

7,0

1000 1500 2000 2500 3000

kW/min m³

spec. power

point of optimal utilisation

speedmin-1

FAD in m³/min9 14 19 24

Specific power of a screw compressor airendat 7 bar related to speed and free air delivery (FAD)

Economic Appraisal

AS 36 / 7.5 bar ( g ) ( 22 KW ) = 3.68 CU.m / min ( 3680l / min )

Full load Input power = 25.8 KWUnload = 6.9 KW

Load Hour----------------- = Duty Cycle in %Service Hour

Example: Example:

การทํางานของโรงงาน 12 ชม. / วัน = 60 % Load

Power Full Load = 60 X 12 X 25.8 X 3.5 = 650 บาท

100

Power Unload = (100-60) X 12 X 6.9 X 3.5 = 115 บาท

100

Total = 765 บาท ตอวัน

ปริมาณลมที่ใชตอวัน = 60 X 12 X 60 X 3.68 = 1589 CU . m.

100

สรุปคากระแสไฟตอ CU . m . = 765 = 0.48 บาท

1589

ตัวอยาง การคํานวณหาคาพลังงานไฟฟาของปมลม

ปริมาณลมรั่ว = 500 l / min

ปริมาณลมรั่วตอวัน = 12 X 500 X 60 = 360 CU. m.

1000

เงินที่ตองจายคาไฟสําหรับลมรั่วตอวัน = 360 X 0.48 = 172 บาท

ถาคิดตอป = 172 X 26 X 12

= 53900 บาท / ป

Documents

Compressed Air a+