171029210-DLS01E-0102

Kaeser Kompressoren 2000 1 http://www.kaeser.com

1. Training Course in Compressed Air Technology


Training Course in

Compressed Air Technology


Topics

The principles of heat recovery

Basic principles of compressed air technology

The generation of compressed air

The treatment of compressed air

Economic appraisal

Control systems Sizing a compressor installation

Planning a compressor installation

The compressed air system


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

Compressed air is ...

... compressed atmospheric air

... a mixture of gases

... compressible

... an energy carrier

user

air main

air treatment

Air centre

Power station

grid system

transformer

user What is compressed air?



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

= Ohm

W = Watt

Hz = Hertz



Physical laws

COMPRESSED AIR is atmospheric air under pressure. That means energy is stored in the air.

When the compressed air expands again this energy is released as WORK.

pressure (energy)

EXPANSION

WORK



nitrogen

78%

oxygen 21%

other gasses 1%

Components of air



...is generated by the weight of the atmosphere. It is dependent on the DENSITY of the air and the height:

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

Atmospheric pressure...



atmospheric pressure

vacuum 100%

0%

pamb

Absolute pressure ...

... is the pressure measured from absolute zero. It is used for all theoretical approaches and is required in vacuum and blower techniques.

Gauge pressure ...

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


absolute pressure

gauge pressure vacuum

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

Pg


Generally: Equivalents

105 Pa = 1 bar

1 MPa = 10 bar

Gauge pressure

1 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 m (A)

Pressure (p) = Force (F)

Area (A)

Definition of pressures



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

Heat dissipation

Natural laws Isotherms (constant temperature)

p0 x V0 = p1 x V1 = constant



Heat dissipation

V

p

p1

p0

V1 V0 dV

T0 = T1

1

0

Isotherms (constant temperature)



If heat is applied under constant pressure, The air volume behaves directly proportional to its absolute temperature.

Application of heat

Natural laws Isobars ( constant pressure )



V

p

p0= p1 0

V1

1

V0 dV

T1

T0

p0 = p1 Application of heat

Isobars (constant pressure)



If heat is applied with constant volume, the pressure behaves directly proportional to the absolute temperature.

Application of heat

Natural laws Isochors (constant volume)


p

p


p

p1

p0

V0=V1

V

T0

T1

1

0

Application of heat V0=V1

Isochors (constant volume)



If the volume is reduced and heat cannot be dissipated, temperature increases with the pressure

p

V

p1

p0

V1 V0

T1

T0

1

dV

Heat insulation

0

Adiabatic or Isentropic (no heat transfer)


p p


Isentropic

Isothermal p1

p0

Pspec kW

m3/min [ ] n = 1.4

n = 1.1

n = 1.3

Theoretical performance requirement (specific, for compression from 1 bar absolute)

n = 1.0



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

barm

K

J

kgK

Gas equation



Volume according

to DIN 1343

(normal

physical state)

Volume according

to DIN/ISO 2533

Volume related

to atmosphere

(normal state)

Volume related

to operating state

Temperature Density Relative

humidity Pressure

0C =

273,15K

1,01325

bar 0%

1,294

kg/m

15C =

288,15K

1,01325

bar 0%

1,225

kg/m

atmospheric

temperature

atmospheric

pressure

atmospheric

humidity variable

working

temperature

working

pressure variable variable

Definition of volumes



7 m atmospheric

air volume

ambient air pressure 1 bar (a)

working pressure 7 bar (a) = 6 bar (g)

1 working m

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 pressure 7 bar (a) = 6 bar (g)

Expansion:

Working pressure p1, V1

Volume


p

p


VN = Normal volume to DIN 1343

VI = Volume at inlet conditions

TN = Temperature to DIN 1343, TN = 273.15K

TI = Maximum temperature at the installation in K

pN = Air pressure to DIN 1343, pN = 1.01325 bar

pI = Lowest air pressure at the installation in bar

Hrel = Maximum relative humidity in the air at the installation

pD = Saturation pressure of the water vapour contained in the

air

in bar, dependent on the temperature of the air

VI x TN x (pI - (Hrel x pD))

pN x TI VN =

Conversion of normal volume to volume according to DIN 1343



-10 0,00260

-9 0,00280

-8 0,00310

-7 0,00340

-6 0,00370

-5 0,00400

-4 0,00440

-3 0,00480

-2 0,00520

-1 0,00560

0 0,00610

1 0,00640

2 0,00710

3 0,00740

4 0,00810

5 0,00870

6 0,00940

7 0,01000

8 0,01070

9 0,01150

10 0.0123

11 0.0131

12 0.0140

13 0.0150

14 0.0160

15 0.0170

16 0.0182

17 0.0184

18 0.0206

19 0.0220

20 0.0234

21 0.0245

22 0.0264

23 0.0281

24 0.0298

25 0.0317

26 0.0336

27 0.0356

28 0.0378

29 0.0400

30 0.0424

31 0.0449

32 0.0473

33 0.0503

34 0.0532

35 0.0562

36 0.0594

37 0.0627

38 0.0662

39 0.0699

40 0.0738

41 0.0778

42 0.0820

43 0.0864

44 0.0910

45 0.0968

46 0.1009

47 0.1061

48 0.1116

49 0.1174

50 0.1234

Saturation pressure pD (bar) at air temperature t ( C)

t pD pD t pD t

Extract from the table for the saturation pressure of water vapour at saturation



Flow velocity in air lines

V = flow volume

v = velocity

A = pipe sectional area

V = A1 x v1 = A2 x v2 A1

A2

v2

v1 =

A1 v1

A2 v2

valid is:



Flow profile

pipe wall

border layer

flow velocity



Flow types

We differentiate between:

laminar (even) and turbulent (swirling) flow



Compressed air in motion

Pressure loss

is dependent on:

sectional area

velocity

pipe length

internal surface area of the pipe

Pre

ss

ure

(b

ar)

length (m)



for logical circuits:

for pneumatic systems ( ISO 1219):

Compressor Double-acting

cylinder Silencer Cooler

Safety valve

Pressure measurement

- pressure gauge

Temperature measurement - thermometer

Filter or strainer

AND function NOT function OR function

Some graphical symbols


171029210-DLS01E-0102

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Transcript of 171029210-DLS01E-0102