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 |
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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