Mathematical operation
Mathematical
operation
÷
=
x
=
x
=
÷
=
x
=
COAL
1000
......................
......................
.....................
10 bar g
Steam pressure
Feedwater temperature
kg / tonne
tonne
£ / tonne
£/1000
kg steam
Heat input required (see table 1)
2445
.....................
Total heat input
2445000
.....................
Calorific value of fuel (see table 2)
42500
.....................
Net fuel needed
57.53
.....................
85% x 1.18
Boiler efficiency
80% x 1.25
1.25
Mathematical
operation
=
x
=
75% x 1.34
.....................
70% x 1.43
Actual fuel needed
71.9
.....................
OIL
S.G
Heavy 9.7
Medium 9.5
Light 9.35
0.97
1000
.....................
Mathematical
operation
80 °C
Units
kJ/kg
kg
kJ
kJ/kg coal or oil
kJ / kWh gas
kg coal or oil
kWh gas
kg coal or oil
kWh gas
GAS
÷
.....................
74.1
.....................
£0.40
.....................
£29.65
.....................
litre
£ / litre
£/1000
kg steam
x
÷ 100 =
.............
.............
pkWh
£/1000
kg steam
Boiler
pressure
bar g
Feedwater temperature °C
10
20
30
40
50
60
70
80
90
100
110
1
2665
2623
2581
2539
2497
2455
2413
2371
2329
2287
2245
5
2715
2673
2631
2589
2548
2506
2464
2421
2381
2338
2295
6
2722
2680
2638
2596
2555
2513
2471
2428
2388
2345
2302
7
2727
2685
2643
2601
2560
2518
2476
2433
2393
2350
2307
10
2740
2697
2655
2613
2573
2531
2489
2445
2406
2363
2319
12
2746
2704
2662
2620
2578
2536
2494
2452
2410
2368
2326
15
2752
2710
2668
2626
2584
2542
2500
2458
2416
2374
2332
17
2755
2713
2671
2629
2587
2545
2503
2461
2419
2377
2335
20
2759
2717
2675
2633
2591
2549
2507
2465
2423
2381
2339
25
2762
2720
2678
2636
2594
2552
2510
2468
2426
2384
2342
COAL
TYPE
CALORIFIC VALUE (kJ/kg)
ANTHRACITE
32,500
GOOD BITUMINOUS COAL
30,000
GOOD AVERAGE
INDUSTRIAL COAL
28,000
POOR AVERAGE
INDUSTRIAL COAL
21,000
OIL
GRADE
VISCOSITY
SPECIFIC
GRAVITY
CALORIFIC
VALUE (kJ/kg)
cSt
RED. 1
SECS
GAS OIL
4
35
0.835
45,600
LIGHT
50
210
0.935
43,500
MEDIUM
230
950
0.95
43,000
HEAVY
900
3500
0.97
42,500
GAS
3,600 kJ / kWh
11.5.1
General information
Useful calculation data
Local regulations may restrict the use of this product to below the conditions quoted.
In the interests of development and improvement of the product, we reserve the right to change the specification without notice.
© Copyright 2013
AI-GAB-03
AB Issue 4
The Cost of Steam
- Metric
The cost of steam is usually expressed in terms of the cost to raise 1000 kg. The calculation itself is relatively straight forward and this AIS
simplifies the task by the use of a forced path calculation sheet. A blank format is available overleaf.
Example: Boiler operating pressure - 10 bar g, feedwater temperatures 80°C. Fuel used is heavy oil at £0.40 / litre and boiler efficiency is 80%.
Table 1
Table 2
Heat input in Kilojoules (kJ) required to raise one kilogram (kg)
Calorific value of various fuels (approximate values)
of steam.
