BIRLA INSTITUTE OF TECHNOLOGY AND SCIENCE, PILANI
Work-Integrated Learning Programmes Division
Semester II - 2019-2020
Assignment 1
Course No: POWAB ZC315
Course Name: Power Plant Engineering
Instructions: All questions are compulsory and carries equal marks
Due Date: 27/03/2020
Marks: 10 (5% weightage)
Attempt all questions in a sequence
Highlight your final answers
Assume suitable data wherever necessary and highlight it
___________________________________________________________________________
Q.1
a. In detail, explain the power scenario in India and its way ahead.
b. With the help of suitable example, write down the relative advantages and
disadvantages of base load power plant vs peak load power plant.
Q.2
A hydro-electric plant costs Rs 3000 per kW of installed capacity. The total annual
charges consist of 5% as interest; depreciation at 2%, operation and maintenance at
2% and insurance, rent etc. 1.5%. Determine a suitable two-part tariff if the losses in
transmission and distribution are 12.5% and diversity of load is 1.25. Assume that
maximum demand on the station is 80% of the capacity and annual load factor is 40%.
What is the overall cost of generation per kWh?
Q.3
A steam power plant operates on the reheat Rankine cycle. Steam enters the highpressure turbine at 12.5 MPa and 550°C at a rate of 7.7 kg/s and leaves at 2 MPa.
Steam is then reheated at constant pressure to 450°C before it expands in the lowpressure turbine. The isentropic efficiencies of the turbine and the pump are 85
percent and 90 percent, respectively. Steam leaves the condenser as a saturated
liquid. If the moisture content of the steam at the exit of the turbine is not to exceed
5 percent, determine (a) the condenser pressure, (b) the net power output, and (c)
the thermal efficiency.
Q.4
A steam power plant operates on an ideal regenerative Rankine cycle. Steam enters
the turbine at 6 MPa and 450°C and is condensed in the condenser at 20 kPa. Steam
is extracted from the turbine at 0.4 MPa to heat the feedwater in an open feedwater
1|Page
heater. Water leaves the feedwater heater as a saturated liquid. Show the cycle on a
T-s diagram, and determine
(a) The net work output per kilogram of steam flowing through the boiler, and
(b) The thermal efficiency of the cycle
(c) Repeat Prob. 4 by replacing the open feedwater heater with a closed feedwater
heater. Assume that the feedwater leaves the heater at the condensation
temperature of the extracted steam and that the extracted steam leaves the
heater as a saturated liquid and is pumped to the line carrying the feedwater.
Q.5
Consider a combined gas–steam power cycle as shown in the figure. The topping cycle
is a simple Brayton Cycle that has a pressure ratio of 7. Air enters the compressor at
15°C at a rate of 10 kg/s and the gas turbine at 950°C. The bottoming cycle is a reheat
Rankine cycle between the pressure limits of 6 MPa and 10 kPa. Steam is heated in a
heat exchanger at a rate of 1.15 kg/s by the exhaust gases leaving the gas turbine and
the exhaust gases leave the heat exchanger at 200°C. Steam leaves the high-pressure
turbine at 1.0 MPa and is reheated to 400°C in the heat exchanger before it expands
in the low pressure turbine. Assuming 80 percent isentropic efficiency for all pumps
and turbine, determine:
(a) moisture content at the exit of the low-pressure turbine,
(b) steam temperature at the inlet of the high-pressure turbine,
(c) net power output and the thermal efficiency of the combined plant.
*** END***
2|Page