Pune University BE (Mechanical Engg.) Power Plant Engineering Question Papers

B.E. (Mechanical Engg.) POWER PLANT ENGINEERING (2008 Pattern) (Sem.-II)

Time :3 Hours]                                                                                              [Max. Marks :100

Instructions to the candidates :

1)            Answer 3 questions from Section -1 and 3 questions from Section – II.

2)            Answers to the two sections should be written in separate books.

3)            Neat diagrams must be drawn wherever necessary.

4)            Pigures to the right indicate full marks.

5)            Use of logarithmic tables slide rule, Mollier charts, electronic pocket calculator and steam tables is allowed.

6)            Assume suitable data, if necessary.

SECTION – I Unit-I

QIA a) What are the different types of power plants where electricity is produced in bulk quantities? Why electricity is the most convenient form of energy. [6] b) What are the factors you will consider for locating the conventional base load thermal power plants?         [10]

OR

Q2) a) What do you understand by radioactive decay? What are radioisotopes?

Explain.                                                                                                                [4]

b)           What do you mean by half life? Why are half lives regarded as fingerprints of radioisotopes?                                                                                            [4]

c)            Explain the characteristic features of a BWR. Explain with a neat sketch with advantages and disadvantages of BWR.                                                [8]

Unit-II

Q3) Write short notes on:

a)            Mechanical stokers used in thermal power-plants. Explain any one with sketch.

b)           Fluidized Bed Combustion boilers.

c)            Ash handling system.                                                                       [3 x 6 = 18]

OR

 

Q4) a) What is a coal-oil mixture? How is it prepared? What are merits of COM as a boiler fuel?                                                                                                          [8]

b)            What is boiler dranght? Which are its types? How they are Produced? Explain what is balanced dranght.                                                                                     [5]

c)            Why are centrifugal fans with backward-curved blading normally used for FD fans. [5]

Unit-Ill

Q5) a) What are the main features of high pressure boilers? With neat sketch explain any one of these.                                                                                                 [8]

b) What are the advantages of High Pressure boilers. Explain.                  [8]

OR

Q6) a) What is erosion of turbine blades? Explain how it is prevented? [8]

b) Explain ideal regenerative feed heating. Why it is not used in practice? Explain how the practical ‘regeneration’ is achieved?                                                     [8]

SECTION – II Unit-IV

Q7) a) Discuss the phenomenon of a supersaturated flow through a nozzle. [4]

b) Steam at a pressure of 30 bar 8 280oC is passed through a nozzle. The back pressure is 0.5 bar. Find the maximum possible discharge through the nozzle; if the throat area is 5 cm2 @500 mm2). Assuming an isentropic efficiency of 85%; find the loss of energy.       [12]

OR

Q8) a) Explain condenser efficiency and vacuum efficiency.                    [4]

b)            Draw a neat sketch of a modern surface condenser and list its advantages and disadvantages.                                                                                            [6]

c)            What are the sources of air leakage in a condenser? How it affects the condenser performance?                                                                                             [6]

Unit-V

Q9) a) Explain :                                                                             [10]

i)             Nozzle control governing.

ii)           Stage efficiency and reheat factor.

 

b) A 5 0% reaction turbine runs at 3000 rpm. The angles at exit of fixed bladings and inlet of moving blades are 20o. The mean ring diameter is 0.7 met. and steam condition is 1.5 bar 8 0.96 dry. Find the power developed by the stage for 50 kg/sec steam flow and the height of blades.                                                                                                              [8]

OR

Q10)a) Define the terms :- degree of reaction and 50% reaction turbines.

Derive an expression for maximum diagram efficiency for blading of a reaction turbine stage. List the assumptions made.                                                                 [10]

b) Following data refers to the working of a single stage impulse: [8]

i)             Enthalpy drop of steam in nozzle = 500 kJ/kg.

ii)           Blade speed = 300 m/sec.

iii)        Nozzle angle = 25o.

iv)         Outlet Blade angle = 35o.

Calculate the power developed by the turbine 8 stage efficiency.

Unit-VI

Q11)a) Discuss the nature of load duration curves for any two consumers 8 explain the load curve.                                                                                                           [6]

b) The daily load for a power plant is given by the equation, L = @290 + 12t – tP) where “t” is time in hours from 0 to 24 hrs and “L” is load in MW. Calculate: [10]

i)             Maximum demand 8 the time when it occurs.

ii)           Plant load factor.

OR

Q12)a) Discuss in detail how energy cost is calculated.                              [8]

b) A thermal power plant consists of 2 x 60 MW units running for 8000 hours and one 30 MW unit running for 2000 hours per year. Energy produced by the plant is 876 x 106 kwh per year. Determine load factor and plant use factor. Assume maximum demand is equal to the plant capacity.                                                                                               [8]

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