Power Plant Engineering - Jun 2015
Mechanical Engg (Semester 8)
TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.
Answer any one question from Q1 and Q2
1 (a) Explain the factors considered for site the selection of a power station.(6 marks)
1 (b) Discuss the status of power generation by the nonconventional sources in India. What is the role of government in this sector?(6 marks)
1 (c) A power generating unit of 15MW capacity takes the following load
i) Domestic consumers with maximum demand of 8MW at a load factor of 25%.
ii) Cottage industry demand of maximum load of 4MW with a load factor of 45%.
iii) Corporation with street light load with maximum demand of 1MW with 30% load factor.
What is the overall cost of energy per kWh for each type of customers? The capital cost of the plant is Rs 9000/kW and running cost is Rs 40,000,000 per year. Take annual interest rate and depreciation on capital cost as 12%.(6 marks) 10 (a) What are different types of switch gear installations? Discuss their relative merits and demerits.(8 marks) 10 (b) Explain the working of a fuel cell and list out its advantages over other non conventional systems of power generation.(8 marks)
Answer any one question from Q11 and Q12
11 (a) What are the different methods presently adopted in the world to reduce the harmful Greenhouse Effect?(9 marks)
11 (b) Explain the different methods adopted to control Nuclear Pollution.(9 marks)
12 (a) Write short notes on the following points:
i) Acid rain
ii) Thermal Pollution
iii) SMOG(9 marks) 12 (b) What are different methods used to control SO 2 in the flue gases? Explain any two.(9 marks) 2 (a) What is carbon credit? Explain with suitable examples.(6 marks) 2 (b) Explain the principle of economic scheduling of power plants.(6 marks) 2 (c) Find the monthly bill and unit cost for a consumer using the Hopkinon demand rate with the following data.
i) Maximum demand: 14kW
ii) Energy consumption per month: 2400kWh
iii) Demand rate:
0-6kW = Rs 200/kW
7-12kW = Rs 160/kW
6-18kW = Rs 140kW
iv) Energy rates:
First 100kWh = Rs 2.0/kWh
101-500 kWh = Rs 1.6/kWh
501-2000kWh = Rs 1.2/kWh
Over 2000 kWh = Rs 1.0/kWh.
What is the lower possible bill for a month and the unit energy cost for the given energy consumption?(6 marks)
Answer any one question from Q3 and Q4
3 (a) Explain the merits and demerits of pulverized coal firing.(4 marks)
3 (b) How co-generation is achieved using back pressure turbines and pass out turbines?(6 marks)
3 (c) In a thermal power plant steam is condensed in a surface condenser at 14000 kg/hr and the leakage is 6 kg/hr. The vacuum near the suction pump is 69cm of Hg and the temperature is 35°C. The air and the condensate are removed by a wet air pump. Find the capacity and the dimensions of the pump if N = 120 RPM, L/D is 1.2 and the pump is single acting. Take barometric pressure as 760mm of Hg.(6 marks)
4 (a) Explain processes of the coal beneficiation and coal desulphurization.(6 marks)
4 (b) What is a dry cooling tower? When it is recommended? What are the different types of dry cooling tower?(4 marks)
4 (c) In a co-generation plant steam is generated at 50 bars and 500°C and expanded through an isentropic turbine to a condenser pressure of 0.05 bars. The heating load is supplied by extracting steam from turbine at 3 bar which is condensed in a process heater to saturated liquid at 3 bar
and then pumped back to boiler. The power load on the system is 6MW and the heating load is 1.2MW. Show the process on TS diagram and find
i) steam generation capacity of boiler in TPH
ii) heat transfer to water in the boiler in kW
iii) rate of cooling water flow across the condenser if the temperature rise of the water is 5°C. Neglect the pump work.(6 marks)
Answer any one question from Q5 and Q6
5 (a) With a suitable diagram explain the schematic layout of a hydro power with.(5 marks)
5 (b) Discuss the performance characteristics of a gas turbine power plant.(5 marks)
5 (c) Compare the steam, hydro and gas power plant on the basis of site, initial cost, fuel cost, maintenance cost, cooling water requirement.(6 marks)
6 (a) Explain the following terms:
iii) Surge tank
iv) Draft tubes
v) Pumped storage plant
vi) Specific speed.(6 marks) 6 (b) What is free piston engine? Discuss the relative merits and demerits.(4 marks) 6 (c) In an open cycle gas turbine power plant compressor is driven by the high pressure turbine. Power is produced by low pressure turbine. The exhaust gases are passed through the regenerator. Using the following data determine the air flow rate for 2MW power produced and thermal efficiency of the plant.
i) isentropic efficiency of compressor and turbines: 88%
ii) Compressor inlet conditions: 27°C and 1 bar
iii) Pressure ratio:7
iv) Regenerator effectiveness: 0.8
v) Maximum temperature in the cycle: 900°C
Assume air flow rate to be equal to the gas flow rate, specific heat for air and gases as 1.005 and 1.128kJ/kgK, γ for air and gases as 1.4 and 1.34 respectively.(6 marks)
Answer any one question from Q7 and Q8
7 (a) Draw a neat diagram of CANDU type of reactor and give its advantages and disadvantages over other types of reactors.(8 marks) 7 (b) Draw a typical layout of Diesel Power Station and Explain.(8 marks) 8 (a) What different Moderators are used in practice? What different properties make them as suitable Moderators?(8 marks) 8 (b) Why the starting of Diesel Plant is more difficult? What different methods are used for starting Diesel Engine? Which method is common and why?(8 marks)
Answer any one question from Q9 and Q10
9 (a) What is the function of bus bar? Draw different types of Bus bar arrangements and discuss the relative merits and Demerits.(8 marks) 9 (b) Explain single basin and double basin tidal power plant with neat diagrams.(8 marks)