How do you calculate the Deaerator & HP heaters steam consumption???

DEAERATORS:

What is the function of Deaerator?

Functions of deaerator

To remove the dissolved oxygen from deaerator & bringing down to <0.005 ppm

To heat the feed water

To provide NPSH to Boiler feed pumps

Acts as surge for feed water storage device

2-Which steam is used for deaerator?

Saturated steam having pressure from 0.3 to 3 kg/cm2 and temperature 130 deg C to 200 deg C

3-What are the pipe lines connected to Deaerator & storage tank?

Inlet lines:

Make up water line

Condensate water line from CEP

Return condensate water from process

Recirculation water line from BFP

Balance leak off water lines from BFP

Condensate water from HP & LP heaters

Steam line from turbine extraction or PRDSH

Out let lines:

Feed water line to BFP suction

Deaerator overflow line

Deaerator storage tank drain line

Understanding with examples.

1-Calculate the steam consumption of deaerator based on following given data

Sl No.

Particular

UOM

Value

 

1

LP steam flow to deaerator at pressure 1.5kg/cm2G & temperature 135 deg C t

TPH

 

?

 

2

Feed water outlet temperature from deaerator

0C

 

105

 

3

Feed water outlet flow from deaerator

TPH

 

     125

 

4

CEP water flow to deaerator at temperature 50 deg C flow

TPH

 

120

 

5

Make up water to deaerator at temperature 25 deg C

TPH

 

5

        

 

 

 

 

 

 

 

 

 

Solution:

Enthalpy of steam at pressure 1.5 kg/cm2 & temperature 135 deg C = 653 kcal/kg

Enthalpy of CEP water at temperature 50 deg C = 50 kcal/kg

Enthalpy of makeup water at temperature 25 deg C = 25 kcal/kg

Enthalpy of deaerator outlet feed water = 106 kcal/kg

Mass of steam = (Feed water flow X Enthalpy –CEP flow X Enthalpy-Makeup water X Enthalpy) / (Enthalpy of steam-Enthalpy of deaerator outlet water)

Mass of steam      = 125 X 106 -120 X 50 -5 X 25 / (653-106)

Mass of steam = 13.02 MT

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2-Calculate the steam consumption of deaerator based on following given data

Sl No.

Particular

UOM

Value

 

1

LP steam flow to deaerator at pressure 2.5 kg/cm2G & temperature 150 deg C t

TPH

 

?

 

2

Feed water outlet temperature from deaerator

0C

 

128

 

3

Feed water outlet flow from deaerator

TPH

 

     210

 

4

CEP water flow to deaerator at temperature 45 deg C flow

TPH

 

30

 

5

Make up water to deaerator at temperature 25 deg C

TPH

 

20

6

Process return condensate at temperature 95 deg C

TPH

160

        

 

 

 

 

 

 

 

 

 

 

 Solution:

Enthalpy of steam at pressure 2.5 kg/cm2 & temperature 150 deg C = 658.4 kcal/kg

Enthalpy of CEP water at temperature 45 deg C = 45 kcal/kg

Enthalpy of makeup water at temperature 25 deg C = 25 kcal/kg

Enthalpy of deaerator outlet feed water = 129 kcal/kg

Enthalpy of return condensate water = 96 kcal/kg

Mass of steam = (Feed water flow X Enthalpy –CEP flow X Enthalpy-Makeup water X Enthalpy-Return condensate X Enthalpy) / (Enthalpy of steam-Enthalpy of deaerator outlet water)

Mass of steam      = (210 X 129 -30 X 45 -20 X 25-160 X 96) / (658.4-129)

Mass of steam = 18.66 MT

HP & LP heaters:











1-What are the applications of HP & LP heaters?

HP & LP heaters are used to heat the feed water & to improve the cycle efficiency

 

2-What are the various pipe lines connected to HP heaters?

Inlet lines:

1-Feed water inlet line

2-Bleed steam line from Turbine

Outlet lines:

1-Feed water outlet line

2-Condensate outlet line

Understanding with examples.

A HP heater is used to heat the 105 TPH feed water from 105 °C to 150 °C by using turbine bleed steam at 8 kg/cm2 and 200 °C. The condensate returning from heater is at 125 °C, calculate the quantity of steam used.

 Given that,

Qf = 105 TPH

Tf1 = 105 °C

Tf2 = 150 °C

Hg at pressure 8 kg/cm2 & temperature 200 °C =677 kcal/kg

Enthalpy of condensate water Hf = 126 kcal/kg

Heat lost by the steam = Heat gained by feed water

Ms X (Hg-Hf) = Mw X (Tf2-Tf1)

Ms X (677-126) = 105 X (150-105)

Ms = 8.57 TPH

 

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