Power Plant Engineering - May 2015

Mechanical Engineering (Semester 7)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks.

Write short notes on any four of the following:

1 (a) Load management of power plant. (5 marks)

1 (b) Benefit of cogeneration. (5 marks)

1 (c) Mechanical dust collectors. (5 marks)

1 (d) Surge tank (5 marks)

1 (e) Cooling system for diesel power plant. (5 marks)

1 (f) Water hammer and its remedial measures. (5 marks)

2 (a) Prove that the condition for economic loading of different units for a power plant site is $$ \dfrac {dI_1} {dL_2} = \dfrac {dI_2}{dL_2} = \dfrac {dI_3} {dL_3} = \cdots \ \cdots = \dfrac {dI_n}{dL_n} $$
(10 marks)

2 (b) A 300 MW thermal power plant is to supply power to system having maximum and minimum demand of 240 MW and 180 MW respectively in a year. Assuming the load duration curve to be a straight line estimate the Load Factor and Capacity Factor of the plant. (10 marks)

3 (a) Explain with a neat sketch the operation of Pressurised Water Reactor. (10 marks)

3 (b) Calculate the cost of generation per kWh for a power station having the following data:
i) Installed capacity of the plant = 210 MW
ii) Capital Cost: Rs180000/kW
iii) Rate of interest and depreciation= 12%
iv) Annual Load Factor = 60%
v) Annual capacity Factor= 54%
vi) Annual Running Charges = Rs 200×10⁶
vii) Energy Consumed by power plant auxillaries = 6%.
Calculate the cost of power generation per kWh and the reverse capacity. (10 marks)

4 (a) In a closed cycles gas turbine there is a two stage compressor and two stage turbine. All the components are mounted on the same shaft. The pressure and temperature at the inlet of the first compressor are 1.5 bar and 20°C. The maximum cycle temperature and pressure are limited to 750°C and 6 bar. A perfect intercooler is used between the two stage compressor and a reheater is used between th turbine. Gases are reheated to 750°C before entering into the LP turbine. Assuming the compressor and turbine efficiencies as 82% calculate (i) The overall efficiency of the cycle and (ii) The mass of the fluid circulated if the power developed by the plant is 350 kW. (10 marks)

4 (b) The runoff data of a river at a particular site is tabulated below:
i) Draw the hydrograph and find the mean flow.
ii) Draw the flow duration curve
iii) Find the power developed if the hend available is 90m and the overall efficiency of generation is 86%. Assume each month of 30 days.

5 (a) What are the performance characteristics of a coal based thermal power plant. Discuss in brief the factors to be considered for selection of site for locating the plant. (10 marks)

5 (b) A six cylinder four strokes SI engine having a piston displacement of 700 cm³ per cylinder developed 78kW at 3200 RPM and consumed 27 kg of petrol per hour. The calorific value of petrol is 44 Mj/kg. Estimate (i) Volumetric efficiency of the engine if the air fuel ratio is 12 on mass basis and intake air is at 0.9 bar and 32°C. (iii) The Brake Thermal Efficiency and (iv) Brake torque. (10 marks)

6 (a) What are advantages of Fluidised Bed Combustion. Explain with a neat sketch the operation of Circulating Fluidised Bed Boiler. (10 marks)

6 (b) Discuss the effect of reheating and regeneration on the performance of Steam Power plant. (10 marks)

7 (a) List the advantages of a diesel power plant. (4 marks)

7 (b) Discuss in brief the disposal of radioactive waste. (6 marks)

7 (c) Explain with a neat sketch any one type of Flue Gas Desulphurisation plant. (10 marks)