Condenser Calculation, Using Thermo Utilities, MS Excel Add-ins

 

A surface condenser is required to deal with 15 000 kg/h wet steam. Wet steam temperature is 37 C and enters the condenser with 0.95 quality (dryness fraction is 0.95). The water used for cooling has the following data:

- Inlet pressure 1.20 bar, inlet temperature 7 C

- Outlet pressure 1.013 bar, outlet temperature 22 C

Calculate the flow rate of cooling water and tube surface of the condenser. Assume that the cooling water velocity through tubes is 1.5 m/s
Inputs

Units

Wet steam inlet temperature

37

C

Steam quality

0,95

.

Cooling water inlet temperature

7

C

Cooling water inlet pressure

1,2

bar

Cooling water outlet temperature

22

C

Cooling water outlet pressure

1,013

bar

Steam mass flow

15000

kg/h

Cooling water speed

1,5

m/s

Outputs

.

.

Wet steam pressure

0,06274

bar

Enthalpy of steam at inlet

2448,28

kJ/kg

Entropy of condense

154,92

kJ/kg

Rejected heat/hour

34400441,72

kJ/h

Rejected heat/second

9555,68

kJ/s = kW

Enthalpy of water at inlet

29,53

kJ/kg

Enthalpy of water at outlet

92,31

kJ/kg

Water mass flow

547885,14

kg/h

The overall heat transfer coefficient can be calculated according to BEAMA or HEI standards.

BEAMA: British Electrical and Allied Manufacturers Association

BEAMA publication on the recommended practice for design of surface type steam condenser

HEI: Heat Exchanger Institute

HEI standards for steam surface condensers

Outputs

Unit

Heat transfer coeff.(BEAMA)

2,95235

KW/m2,K

Logarithmic mean temp. diff.

49,83

degree K

Required area

64,96

m2

If we use the less conservative HEI method we obtain the following:
Outputs

Unit

Heat transfer coeff.(HEI)

3,60991

kW/m2,K

Required area

53,12

m2


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