ACTIVITY 3: COAL POWER PLANTS
EE133L POWER PLANT ENGINEERING LABORATORY
LEARNING OUTCOMES:
1. Solve problems involving the efficiency, power and energy of the coal thermal power plants.
2. Solve for the cost of producing certain amount of energy in coal thermal power plants.
3. Calculate the coal consumption of the power plant.
4. Solve problem involving heat rate.
DISCUSSION
HEAT ENERGY CONVERSION FACTORS
1 calorie = 4.186 joules
1 BTU (British Thermal Unit) = 252 calories
1 lb of coal yields 12,500 BTU
1 kW-hr = 3.6 x 106 joules
where: calorie or cal = SI or MKS unit of heat energy
BTU or British Thermal Unit = English or FPS unit of heat energy
Joule or J = unit of energy in SI unit
ILLUSTRATIVE PROBLEMS:
1. The heat rate of a given coal-fired thermal plant is 12,500 BTU/lb. How many pound of coal are
needed to generate 1000 kW-hr? (273 lbs)
1000 𝑘𝑊 − ℎ𝑟 ×
3.6 x 10𝟔 joules
1 𝑐𝑎𝑙
1 𝐵𝑇𝑈
1 𝑙𝑏
×
×
×
= 273 𝑙𝑏
𝑘𝑊 − 𝐻𝑟
4.186 𝑗𝑜𝑢𝑙𝑒𝑠
252 𝑐𝑎𝑙
12500 𝐵𝑇𝑈
2. A certain coal-fired power plant has a heat rate of 2.88 x 106 calories per kW-hr. Coal cost P 2,500
per ton. How much is the fuel cost component of producing one kW-hr? Assuming the heat value of
coal used equal to 13,000 BTU/lb. (P1.00)
1 𝑘𝑊 − ℎ𝑟 ×
2.88 × 106 𝑐𝑎𝑙
1 𝐵𝑇𝑈
1 𝑙𝑏
1 𝑡𝑜𝑛
𝑃 2500
×
×
×
×
= 𝑃1.00
𝑘𝑊𝐻𝑟
252 𝑐𝑎𝑙
13000 𝐵𝑇𝑈
2204 𝑙𝑏
𝑡𝑜𝑛
3. A power plant consumes 100,000 pounds of coal per hour. The heating value of the coal is 12,000
BTU per pound. The overall efficiency of the plant is 36%. What is the kW output of the plant?
(105,487.2 kW)
100000 𝑙𝑏
12000 𝐵𝑇𝑈
252 𝑐𝑎𝑙
4.186 𝐽
1 𝑘𝑊ℎ𝑟
×
×
×
×
× 0.36 = 126,584.64 𝑘𝑊
ℎ𝑟
𝑙𝑏
𝐵𝑇𝑈
𝑐𝑎𝑙
3.6 × 106 𝐽
4. A power plant has an overall efficiency of 30%. If this plant can consume 4200 kg of coal per hour,
estimate the total electric energy produced in one day? Assume the colorific value of the coal being
used is 5000 kcal per kg. (175,812 kW-hr)
4200 𝑘𝑔 24 ℎ𝑟 5000 × 1000 𝑐𝑎𝑙
4.186 𝐽
1 𝑘𝑊ℎ𝑟
×
×
×
×
× 0.3 = 175,812 𝑘𝑊𝐻𝑟
ℎ𝑟
𝑑𝑎𝑦
𝑘𝑔
𝑐𝑎𝑙
3.6 × 106 𝐽
5. A plant has a total operating capacity of 800 kW. The coal consumption is 1900 lbs per hour, heating
value of coal is 9,500 BTU per lb. What approximate percent of the heat in the coal is converted into
useful energy? (15.12%)
1900 𝑙𝑏
9500 𝐵𝑇𝑈
252 𝑐𝑎𝑙
4.186 𝐽
1 𝑘𝑊ℎ𝑟
×
×
×
×
× 𝜂 = 800 𝑘𝑊
ℎ𝑟
𝑙𝑏
𝐵𝑇𝑈
𝑐𝑎𝑙
3.6 × 106 𝐽
𝜂 = 15.12 %
GENERAL INSTRUCTIONS:
A. Answer the following problems in a letter size bond paper.
B. Solve neatly. Show all the details of your solution, including circuit diagram(s) if necessary. Box your
final answer(s).
C. There will be corresponding deductions from your accumulated scores for not following the general
instructions and submitting on time.
D. Save your work in PDF format and upload to BBL.
1. (20 pts) To produce 1 kW-hr, a power plant burns 0.9 lb of coal with a heating value of 13,000 BTU.
What is the heat rate of the plant in BTU/kwHr?
2. (20 pts) A coal power plant has an overall plant efficiency of 28%. Coal with a heating value of
12,000 BTU per pound cost P 1.50 per pound. What is the cost producing 1 kW-hr in pesos?
3. (20 pts) A 100 MW thermal plant has an overall efficiency of 34%. If the coal used has a heating
value of 10,800 BTU per pound, calculate the coal consumption of the plan per kW-hr output in
pounds (lb).
REFERENCES:
1. Power Plant Engineering
P K Nag
2. 1001 Solved Problems in Electrical Engineering
Romeo A. Rojas Jr.
3. Electrical Engineering Reviewer Series Volume 1
Eng’r. Eldorado L. Corpuz