Mathematical operation
Mathematical
operation
÷
=
x
=
x
=
÷
=
x
=
COAL
2240
......................
......................
.....................
150 psi g
Steam pressure
Feedwater temperature
lb/ton
ton
£/ton
£/1000
lb steam
Heat input required (see table 1)
1049
.....................
Total Heat Input
1049000
.....................
Calorific value of fuel (see table 2)
18300
.....................
Net fuel needed
57.3
.....................
85% x 1.18
Boiler efficiency
80% x 1.25
1.25
Mathematical
operation
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
1000
.....................
Mathematical
operation
180 °F
Units
Btu/lb
lb
Btu
Btu/lb coal or oil
Btu/Therm gas
lb coal or oil
Therm gas
GAS
lb coal or oil
Therm gas
÷
=
x
=
9.7
.....................
7.38
.....................
£1.80
.....................
£13.28
.....................
gallon
£ / gallon
£/1000
lb steam
x
=
.............
.............
£ / therm
£/1000
lb steam
Boiler
pressure
psi g
Feedwater temperature °F
50
70
80
100
120
140
160
180
200
212
250
15
1146
1126
1116
1096
1076
1056
1036
1016
996
984
946
80
1169
1149
1139
1119
1099
1079
1059
1039
1019
1007
969
90
1171
1151
1141
1121
1101
1081
1061
1041
1021
1009
971
100
1172
1152
1142
1122
1102
1082
1062
1042
1022
1010
972
150
1179
1159
1149
1129
1109
1089
1069
1049
1029
1017
979
170
1180
1160
1150
1130
1110
1090
1070
1050
1030
1018
980
200
1182
1162
1152
1132
1112
1092
1072
1052
1032
1020
982
250
1185
1165
1155
1135
1115
1095
1075
1055
1035
1023
985
300
1186
1166
1156
1136
1116
1096
1076
1056
1036
1024
986
350
1187
1167
1157
1137
1117
1097
1077
1057
1037
1025
987
COAL
TYPE
CALORIFIC VALUE (Btu/lb)
ANTHRACITE
14,000
GOOD BITUMINOUS COAL
13,000
GOOD AVERAGE
INDUSTRIAL COAL
12,000
POOR AVERAGE
INDUSTRIAL COAL
9,000
OIL
GRADE
VISCOSITY
SPECIFIC
GRAVITY
CALORIFIC
VALUE (Btu/kg)
cSt
RED. 1
SECS
GAS OIL
4
35
0.835
19,600
LIGHT
50
210
0.935
18,700
MEDIUM
230
950
0.95
18,500
HEAVY
900
3500
0.97
18,300
GAS
100,000 Btu/Therm
11.5.3
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-04
AB Issue 3
The Cost of Steam
- Imperial
The cost of steam is usually expressed in terms of the cost to raise 1000lbs. 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 - 150 psi g, feedwater temperatures 180°F. Fuel used is heavy oil at £1.80 / gallon and boiler efficiency is 80%.
Table 1
Table 2
Heat input in British Thermal Units (Btu) required to raise
Calorific value of various fuels (approximate values)
one pound (lb) of steam.
