SOLUTIONS MANUAL
for
COMBUSTION ENGINEERING
(3d Edition)
April 2022
Kenneth M. Bryden
Iowa State University
Kenneth W. Ragland
University of Wisconsin – Madison
Song-Charng Kong
Texas Tech University
** Immediate Download
** Swift Response
** All Chapters included
, 2-1
Chapter 2. Fuels
1. In the United States electricity is sold using the SI units of kilowatt (kW) or megawatt (MW), and fuel
for power generation stations is generally purchased using English units, e.g., British thermal unit (Btu),
gallon (gal), and ton (T). An industrial power plant has an average annual load of 100 MW (electrical).
If the overall thermal efficiency is 33% (based on HHV), what is the annual cost of fuel if the plant is
fired with (a) natural gas, (b) No. 2 fuel oil, and (c) bituminous coal? Use the data from Tables 2.2, 2.7,
and 2.13. Assume the cost of natural gas is $5/million Btu, the cost of No. 2 fuel oil is $3/gal, and the
cost of bituminous coal is $60/ton (1 ton = 2000 lbm).
Given: 100 MW electrical average annual output
η = 0.33
Fuel cost = $5/MBtu (natural gas)
Fuel cost = $3/gal (No. 2 fuel oil)
Fuel cost = $60/ton (bituminous coal)
Find: Annual fuel costs
Solution:
100 MW 8760 hr
Eelec = × = 876,000 MWh yr
1 yr
876,000 MWh elec MWh f 3412 MBtu
Qin = × × = 9.06 × 10 6 MBtu yr
yr 0.33 MWh elec MWh f
Natural gas
9.06 × 10 6 MBtu $5
Annual cost ng = ×
yr MBtu
Annual cost ng = $45.3 × 10 6 yr ⇐ (a)
, 2-2
No. 2 Fuel Oil
HHVNo2 = 45.4 MJ kg (Table 2.7)
ρNo2 = 0.865 (Table 2.7)
45, 400 kJ 1 Btu lb m MBtu ( 0.865 )10 3 kg 1 lb m ft 3 0.1337 ft 3
HHVNo2 = × × 6 × × ×
kg 2.324 kJ kg 10 Btu m3 16.02 kg m 3 gal
HHVNo2 = 0.1410 MBtu gal
$3 gal
Fuel cost No2 = × = $21.30 MBtu
gal 0.1410 MBtu
9.06 × 10 6 MBtu $21.30
Annual cost No2 = ×
yr MBtu
Annual cost No2 = $193 × 10 6 yr ⇐ (b)
Bituminous coal
HHVcoal = 14,000 Btu lb m (Table 2.13)
$60 ton lb m 10 6 Btu
Fuel cost coal = × × × = $2.14 MBtu
ton 2000 lb m 14,000 Btu MBtu
9.06 × 10 6 MBtu $2.14
Annual cost = ×
yr gal
Annual cost = $19.4 × 10 6 yr ⇐ (c)
Summary
Fuel Fuel cost Annual cost
Natural Gas $5.00/MBtu $45.3 million/yr
No. 2 Fuel Oil $21.30/MBtu $193 million/yr
Bituminous Coal $2.14/MBtu $19.4 million/yr
, 2-3
2. In the United States energy for household heating is generally sold using English units, e.g., therm, gal,
and cord. A house in Wisconsin requires 1200 therms of thermal energy during the heating season.
Calculate the cost of fuel if the furnace uses (a) natural gas with an efficiency of 70%; (b) No. 2 fuel
oil, efficiency 65%; (c) kerosene, efficiency 99.9% (unvented); and (d) wood with l5% moisture with
an efficiency of 50%. Use the data in Tables 2.2, 2.7, and 2.13. The efficiencies are based on the HHV.
Assume the cost of natural gas is $8/MBtu, the cost of No. 2 fuel oil is $3/gal, the cost of kerosene is
$3.50/gal, and the cost of wood is $100/cord. Assume the bulk density of cord wood is 30 lbm/ft3.
Given: Qheat = 1200 therm/yr
Fuel Fuel cost Thermal efficiency
Natural Gas $8.00/MBtu 70%
No. 2 Fuel Oil $3.00/gal 65%
Kerosene $3.50/gal 99.9%
Wood (15% MC as-recd) $100/cord 50%
Find: Annual fuel costs
Solution:
Natural gas
1200 Therm heat Therm in 0.1 MBtu
Qin = × × = 171.4 MBtu yr
yr 0.70 Therm heat Therm in
171.4 MBtu $8
Annual cost ng = ×
yr MBtu
Annual cost ng = $1370 yr ⇐ (a)
for
COMBUSTION ENGINEERING
(3d Edition)
April 2022
Kenneth M. Bryden
Iowa State University
Kenneth W. Ragland
University of Wisconsin – Madison
Song-Charng Kong
Texas Tech University
** Immediate Download
** Swift Response
** All Chapters included
, 2-1
Chapter 2. Fuels
1. In the United States electricity is sold using the SI units of kilowatt (kW) or megawatt (MW), and fuel
for power generation stations is generally purchased using English units, e.g., British thermal unit (Btu),
gallon (gal), and ton (T). An industrial power plant has an average annual load of 100 MW (electrical).
If the overall thermal efficiency is 33% (based on HHV), what is the annual cost of fuel if the plant is
fired with (a) natural gas, (b) No. 2 fuel oil, and (c) bituminous coal? Use the data from Tables 2.2, 2.7,
and 2.13. Assume the cost of natural gas is $5/million Btu, the cost of No. 2 fuel oil is $3/gal, and the
cost of bituminous coal is $60/ton (1 ton = 2000 lbm).
Given: 100 MW electrical average annual output
η = 0.33
Fuel cost = $5/MBtu (natural gas)
Fuel cost = $3/gal (No. 2 fuel oil)
Fuel cost = $60/ton (bituminous coal)
Find: Annual fuel costs
Solution:
100 MW 8760 hr
Eelec = × = 876,000 MWh yr
1 yr
876,000 MWh elec MWh f 3412 MBtu
Qin = × × = 9.06 × 10 6 MBtu yr
yr 0.33 MWh elec MWh f
Natural gas
9.06 × 10 6 MBtu $5
Annual cost ng = ×
yr MBtu
Annual cost ng = $45.3 × 10 6 yr ⇐ (a)
, 2-2
No. 2 Fuel Oil
HHVNo2 = 45.4 MJ kg (Table 2.7)
ρNo2 = 0.865 (Table 2.7)
45, 400 kJ 1 Btu lb m MBtu ( 0.865 )10 3 kg 1 lb m ft 3 0.1337 ft 3
HHVNo2 = × × 6 × × ×
kg 2.324 kJ kg 10 Btu m3 16.02 kg m 3 gal
HHVNo2 = 0.1410 MBtu gal
$3 gal
Fuel cost No2 = × = $21.30 MBtu
gal 0.1410 MBtu
9.06 × 10 6 MBtu $21.30
Annual cost No2 = ×
yr MBtu
Annual cost No2 = $193 × 10 6 yr ⇐ (b)
Bituminous coal
HHVcoal = 14,000 Btu lb m (Table 2.13)
$60 ton lb m 10 6 Btu
Fuel cost coal = × × × = $2.14 MBtu
ton 2000 lb m 14,000 Btu MBtu
9.06 × 10 6 MBtu $2.14
Annual cost = ×
yr gal
Annual cost = $19.4 × 10 6 yr ⇐ (c)
Summary
Fuel Fuel cost Annual cost
Natural Gas $5.00/MBtu $45.3 million/yr
No. 2 Fuel Oil $21.30/MBtu $193 million/yr
Bituminous Coal $2.14/MBtu $19.4 million/yr
, 2-3
2. In the United States energy for household heating is generally sold using English units, e.g., therm, gal,
and cord. A house in Wisconsin requires 1200 therms of thermal energy during the heating season.
Calculate the cost of fuel if the furnace uses (a) natural gas with an efficiency of 70%; (b) No. 2 fuel
oil, efficiency 65%; (c) kerosene, efficiency 99.9% (unvented); and (d) wood with l5% moisture with
an efficiency of 50%. Use the data in Tables 2.2, 2.7, and 2.13. The efficiencies are based on the HHV.
Assume the cost of natural gas is $8/MBtu, the cost of No. 2 fuel oil is $3/gal, the cost of kerosene is
$3.50/gal, and the cost of wood is $100/cord. Assume the bulk density of cord wood is 30 lbm/ft3.
Given: Qheat = 1200 therm/yr
Fuel Fuel cost Thermal efficiency
Natural Gas $8.00/MBtu 70%
No. 2 Fuel Oil $3.00/gal 65%
Kerosene $3.50/gal 99.9%
Wood (15% MC as-recd) $100/cord 50%
Find: Annual fuel costs
Solution:
Natural gas
1200 Therm heat Therm in 0.1 MBtu
Qin = × × = 171.4 MBtu yr
yr 0.70 Therm heat Therm in
171.4 MBtu $8
Annual cost ng = ×
yr MBtu
Annual cost ng = $1370 yr ⇐ (a)
