Fuels
Fuel characteristics
Liquid fuels
Dew point of flue gases
Minimum feed water temperature as a function of fuel sulphur content
Fuel oil SA |
Fuel oil S |
Pinch-point diagrams, boiler system
Pinch-point diagram for gas
Pinch-point diagram for gas
Boiler |
|
Boiler + economiser |
|
Boiler + economiser + condensing heat |
|
Boiler + economiser + condensing heat |
|
Boiler + economiser + condensing heat |
|
Boiler + economiser + air preheating |
|
Boiler + economiser + feed water cooling |
Example: |
|
KCondensate accumulation rate |
c = ṁCo / ṁS |
Make-up water rate |
z = 1 – c |
UL-S |
10,000 x 16 |
System steam output |
10,000 kg/h with pavg = 13 bar |
Surface blowdown rate |
5 % |
Case |
Component |
Efficiency |
|
Component parts |
Total |
||
1 |
Boiler |
88.9 % |
--- |
2 |
Boiler + economiser |
88.9 % + 6.5 % |
95.4 % |
3 |
Boiler + economiser + condensing heat exchanger |
88.9 % + 6.5 % + 2.8 % |
98.2 % |
4 |
Boiler + economiser + condensing heat exchanger |
88.9 % + 6.5 % + 3.8 % |
99.2 % |
5 |
Boiler + economiser + condensing heat exchanger |
88.9 % + 6.5 % + 7.6 % |
100.9 % |
6 |
Boiler + economiser + air preheating |
88.9 % + 6.5 % + 1.7 % |
97.1 % |
7 |
Boiler + economiser + feed water cooling |
88.9 % + 6.5 % + 0.6 % |
96.0 % |
Case studies for combinations of measures for optimum heat recovery
1) z = make-up water rate
2) α = condensate accumulation rate
Pinch-point diagram for oil
Pinch-point diagram for oil
Boiler |
Boiler + economiser |