A coal-burning steam power plant produces a net power of 300 MW with an overall thermal efficiency of 32 percent. The actual gravimetric air–fuel ratio in the furnace is calculated to be 12 kg air/kg fuel. The heating value of the coal is 28,000 kJ/kg. Determine (a) the amount of coal consumed during a 24-hour period and (b) the rate of air flowing through the furnace.
(a)
The amount of coal consume during a 24 hour period.
Answer to Problem 26P
The amount of coal consume during a 24 hour period is
Explanation of Solution
Write the expression for thermal efficiency of power plant.
Here, the net work output of the power plant is
Simplify the Equation (II) as per British thermal unit per hour.
Here, the rate of heat transfer of the power plant is
Determine the amount heat input to the power plant with respect to time.
Here, the change in with respect with time is
Determine the heat supplied to the power plant.
Here, the mass of the coal is
Determine the rate of mass of coal consumed during this period.\
Conclusion:
Substitute
Substitute
Substitute
Thus, the amount of coal consume during a 24 hour period is
Substitute
(b)
The rate of air flowing through the furnace.
Answer to Problem 26P
The rate of air flowing through the furnace is
Explanation of Solution
Determine the rate of air mass flowing through the furnace.
Here, the ration of air-fuel is
Conclusion:
Substitute
Thus, the rate of air flowing through the furnace is
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Chapter 6 Solutions
Thermodynamics: An Engineering Approach
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