General information Useful calculation data
7
Steam pressure
Feedwater temperature
Mathematical operation
Units Btu/lb
Heat input required (see table 1)
x =
lb
1000
Total heat input
Btu
Btu/lb coal or oil Btu/Therm gas
÷
Calorific value of fuel (see table 2)
lb coal or oil Therm gas
=
Net fuel needed
85% x 1.18 80% x 1.25 75% x 1.34 70% x 1.43
x
Boiler efficiency
lb coal or oil Therm gas
=
Actual fuel needed
COAL
OIL
GAS
S.G Heavy 9.7 Medium 9.5 Light 9.35
Mathematical operation
Mathematical operation
Mathematical operation
÷ = x
2240
lb/ton
÷ = x
x
£/therm
ton
gallon
£ / ton
£/gallon £ / 1000 lb steam
£ / 1000 lb steam
÷ 100 =
£ / 1000 lb steam
=
=
Table 1 Heat input in Kilojoules (kJ) required to raise one kilogram (kg) of steam. Boiler pressure psi g Feedwater temperature °F 50 70 80 100 120 140 160 180 200 212 250 15 1146 1126 1116 10961076105610361016 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 Table 2 Calorific value of various fuels (approximate values)
7.5 7
TYPE
CALORIFIC VALUE (Btu / lb)
ANTHRACITE
14,000 13,000 12,000
COAL
GOOD BITUMINOUS COAL
GOOD AVERAGE INDUSTRIAL COAL POOR AVERAGE INDUSTRIAL COAL
9,000
GRADE
VISCOSITY
SPECIFIC GRAVITY
CALORIFIC VALUE (kJ / kg)
cSt
RED. 1 SECS
GAS OIL
4
35
0.835 0.935
19,600 18,700 18,500 18,300
OIL
LIGHT
50
210 950
MEDIUM HEAVY
230 900
0.95 0.97
3500
GAS
100,000 Btu/Therm
AI-GAB-04 AB Issue 3
Page 3 of 3
The Cost of Steam - Imperial
Powered by FlippingBook