RELIANCE JAMNAGAR RPCTEFH - SHEET-1 of 5 PROCEDURE FOR CALCULATION OF THERMAL EFFICIENCY OF FIRED HEATERS THERMAL EFFICIENCY OF FIRED HEATER ENUMERATED BELOW IS BASED ON API 560 Definitions: Thermal efficiency is efficiency is defined as total heat absorbed divided by the total heat input. Total heat absorbed is absorbed is equal to the total heat input minus the total heat losses. Total heat input is input is equal to the sum of the net heat of combustion of the fuel ( LHV ) and the sum of sensible heat of the air, fuel and atomising medium to the system. In case of steam Air Preaheating, it also includes heat input in steam for such purpose. Total heat losses are losses are equal to the sum of radiation heat loss and stack heat loss.
RELIANCE : RPCTEFH - SHEET- 2 of 5 PROCEDURE TO USE THE WORKSHEET The following steps to be followed while using the worksheet. 1. Go to Tools ---> Options ----> Calculation; Select iteration. Input Maximum iterations 100 and Maximum Change 0.001. Select Manual calculation 2. Fuel Oil and Fule Gas composition to be entered in "FUEL_DETAILS" sheet. Also enter LHV of Fuel Oil in the same sheet. 3. If O2 composition of stack is available on wet basis pl. use "EFF_CALCULATION_WET_BASIS" sheet, if it is available on dry basis then use "EFF_CALCULATION_DRY_BASIS" sheet. 4. Input data in column "C" only in sheets "EFF_CALCULATION_WET_BASIS" or "EFF_CALCULATION_WET_BASIS" 5. After entering all the input data, Press F9 OR SAVE the file to refresh calculations.
RELIANCE : RPCTEFH - SHEET- 3 of 5 FUEL COMPOSITION INPUT SHEET Fuel Oil Fuel Composition C= H= LHV (Kcal/kg)
wt%
87.00% 13.00% 10000
Fuel Gas Component
Composition
Nitrogen
6.10%
28
0
0.0000
0.0000
H2O
0.00%
18
0
0.0000
0.0000
0
H2S
0.00%
34
0
0.0000
0.0000
123810
NH3
0.00%
17
0
0.0000
0.0000
67744
CO2
0.60%
44
0
0.0060
0.0000
0
Hydrogen
23.80%
2
0.119
0.0000
0.2380
57796
methane
36.60%
16
0.732
0.3660
0.7320
191760
ethylene
10.20%
28
0.306
0.2040
0.2040
316190
ethane
18.10%
30
0.6335
0.3620
0.5430
341260
propane
1.80%
44
0.09
0.0540
0.0720
488520
propylene
0.00%
42
0
0.0000
0.0000
460430
MW
O2 re q. (K gm ol/ hr )
CO2 g en (Kg mo l/h r)
H2O gen (Kgmol/hr)
LHV
(Kcal/kgmol) 0
RELIANCE : RPCTEFH - SHEET- 4 of 5 WORKSHEET FOR EFFICIENCY CALCULATION OF FIRED HEATER (BASIS: O2 ANALYSIS IN FLUE GAS ON WET BASIS) CALCULATED DATA WITH DIAGRAM AIR INPUT
OUTPUT
1
FO Firing rate (Kg/hr)
3496
2
FG Firing rate (Kg/hr)
0
Fired Duty (MMKcal/hr)
35.0
Sencible Heat Input ex FO (MMKcal/hr)
0.15
Heat Input ex Atomising Steam (MMKcal/hr) Heat Input ex Pilot Gas (MMKcal/hr)
0.11 0.01 0.00
RADIATION LOSS
200.0 30 60.0%
Total Heat Input (MMKcal/hr)
35.2
Qr (MMKcal/hr) =
Heat Input ex Steam Air Preheating (MMKcal/hr) 3
Mol. % O2 in Flue Gas (Wet Basis) o
4
Stack Temp. ( C)
5
Ambient Tem .
6
Relative Humidity of Air
7
o
C
2.60
Cp, av., (Air) (Kca/0K,Kgmole) Cp, av., (H 2O) (Kca/0K,Kgmole)
Moles Water Vap./ Moles Dry Air
0.026
1. Through Flue Gas (MMKcal/hr)
Radiation loss (percent of heat released)
2.93 0.52
Air inlet temp. after steam heater
1.50% 31.0
2. Through Radiation Loss (MMKcal/hr)
9
Total
3.5
10
Atomizing Steam flow (TPH)
11
P il ot Gas flow (k g/ hr)
Total Heat Absorbed (M MKcal/hr)
31.79
0.52
M (Kgmol/hr) (Dry)
2032.7
H2O (V) (Kgmol/hr)
52.8
Enthalpy of air (MMKcal/hr)
0.01
o
12
Fuel Oil Inlet Temp. ( C)
13
Fuel Oil Sp. Heat. (Kcal/kg/0K)
14
Enthalpy of Atomising Steam (Kcal/kg)
CO2 = N2 =
31.0
H2O
200.0
Mol% 11.02% 2.60%
Kgmol/hr 253.5 59.8
69.84% 16.53% 100.00%
1605.8 380.1 2299.1
Stack Heat Loss through Stack 1. Through Dry Flue Gas (kcal/hr)
Thermal Efficiency
2400145
2. Through Water Vap. (kca/hr)
527734
Total (MMKcal/hr)
2.93
Cp, av., (CO 2) (Kca/0K,Kgmole) Cp, av., (N 2) (Kca/0K,Kgmole)
9.75 7.19 6.99
Cp, av., (H 2O) (Kca/0K,Kgmole)
8.17
90.20%
Excess Air Used =
16.3%
Flue Gas Composition
Mole %
CO2 =
11.02%
O2 =
Combustion APH
PROCESS FLUID IN
1.8 0.0 120 0.48 673
STACK
Steam APH
O2 =
Total Loss
8
6.96 7.94
Cp, av., (O 2) (Kca/0K,Kgmole)
FIRED HEATER
2.60%
N2 =
69.84%
H2O =
16.53%
PROCESS FLUID OUT Fuel Gas Heat Supplied ex Fuel Gas (MMKcal/hr)
0.00
FUEL OIL C= H= M (kg/hr) = Cal. Value (Kcal/kg) Heat Supplied ex Fuel Oil (MMKcal/hr)
wt%
Kg/hr
87.00% 13.00% 3496.00 10000 34.96
3041.5 454.5
AIR
Note: 1. Please input your d ata in "C" Column only 2. Am bient Temp. use as datum temp. for simplific ation of calculation
Confidential - Property of Reliance
RELIANCE : RPCTEFH - SHEET- 5 of 5 WORKSHEET FOR EFFICIENCY CALCULATION OF FIRED HEATER (BASIS: O2 ANALYSIS IN FLUE GAS ON DRY BASIS) CALCULATED DATA WITH DIAGRAM AIR INPUT
OUTPUT
1
FO Firing rate (Kg/hr)
4000
2
FG Firing rate (Kg/hr)
6000
Fired Duty (MMKcal/hr)
104.5
Sencible Heat Input ex FO (MMKcal/hr)
0.08
Heat Input ex Atomising Steam (MMKcal/hr) Heat Input ex Pilot Gas (MMKcal/hr)
0.16 3.47 0.23
RADIATION LOSS
184.0 30 60.0%
Total Heat Input (MMKcal/hr)
108.4
Qr (MMKcal/hr) =
Heat Input ex Steam Air Preheating (MMKcal/hr) 3
Mol. % O2 in Flue Gas (Wet Basis) o
4
Stack Temp. ( C)
5
Ambient Temp. ( C)
6
Relat ive Humidity of Air
7
o
3.68
Cp, av., (Air) (Kca/0K,Kgmole) Cp, av., (H 2O) (Kca/0K,Kgmole)
Moles Water Vap./ Moles Dry Air
0.026
1. Through Flue Gas (MMKcal/hr)
Radiation loss (percent of heat released)
7.79 2.61
Air inlet temp. after steam heater
2.50% 109.0
2. Through Radiation Loss (MMKcal/hr)
9
Total
10.4
10
Atomizing Steam flow (TPH)
11
P ilot Gas fl ow (kg /h r)
Total Heat Absorbed (M MKcal/hr)
98.0
2.61
M (Kgmol/hr) (Dry)
6084.2
H2O (V) (Kgmol/hr)
158.2
Enthalpy of air (MMKcal/hr)
3.47
o
12
Fuel Oil Inlet Tem .
13
Fuel Oil Sp. Heat. (Kcal/kg/0K)
14
Enthalpy of Atomising Steam (Kcal/kg)
C
CO2 = N2 =
109.0
Mol% 11.23% 3.68%
Kgmol/hr 634.5 207.9
85.09% 100.00%
4806.5 5648.9 1155.0
H2O
184.0
Stack Heat Loss through Stack 1. Through Dry Flue Gas (kcal/hr)
Thermal Efficiency
6339413
2. Through Water Vap. (kca/hr)
1448942
Total (MMKcal/hr)
7.79
Cp, av., (CO 2) (Kca/0K,Kgmole) Cp, av., (N 2) (Kca/0K,Kgmole)
9.69 7.17 6.97
Cp, av., (H 2O) (Kca/0K,Kgmole)
8.15
90.4%
Excess Air Used =
19.4%
Flue Gas Composition
Mole %
CO2 =
11.23%
O2 =
Combustion APH
PROCESS FLUID IN
2.2 21.1 70 0.48 683
STACK
Steam APH
O2 =
Total Loss
8
7.01 8.05
Cp, av., (O 2) (Kca/0K,Kgmole)
FIRED HEATER
3.68%
N2 =
85.09%
H2O =
0.00%
PROCESS FLUID OUT Fuel Gas Heat Supplied ex Fuel Gas (MMKcal/hr)
64.50
FUEL OIL C= H= M (kg/hr) = Cal. Value (Kcal/kg) Heat Supplied ex Fuel Oil (MMKcal/hr)
wt%
Kg/hr
87.00% 13.00% 4000.00 10000 40.00
3480.0 520.0
AIR
Note: 1. Please input your data in " C" Colum n only 2. Ambient Temp. use as datum temp. for simplific ation of calculation
Confidential - Property of Reliance
