About this previous year paper
KME076 – POWER PLANT ENGINEERING
B.Tech (SEM VII) – Theory Examination
Time: 3 Hours | Max Marks: 100
SECTION A
(Attempt all questions in brief – 2 marks each)
a. What are conventional and non-conventional power plants? Give examples.
Conventional power plants use traditional energy sources like coal, oil, and nuclear fuel. Examples: thermal power plant, nuclear power plant.
Non-conventional power plants use renewable energy sources. Examples: solar, wind, tidal, and geothermal power plants.
b. Differentiate between subcritical and supercritical boilers.
| Subcritical Boiler | Supercritical Boiler |
|---|---|
| Operates below critical pressure | Operates above critical pressure |
| Drum type boiler | Drumless boiler |
| Lower efficiency | Higher efficiency |
c. Define surge tank. What is its function?
A surge tank is a water storage chamber connected to the penstock in a hydroelectric power plant. It absorbs pressure fluctuations and reduces water hammer during sudden load changes.
d. Discuss intercooling and reheating in a gas turbine power plant.
Intercooling reduces compressor work by cooling air between compression stages. Reheating increases turbine output by reheating gases between turbine stages, improving efficiency.
e. Explain the working principle of fast breeder reactors.
Fast breeder reactors produce more fissile material than they consume by converting fertile uranium-238 into plutonium-239 using fast neutrons.
f. Define solar thermal collectors. Give examples.
Solar thermal collectors absorb solar radiation and convert it into heat energy. Examples: flat plate collectors, parabolic trough collectors.
g. Difference between horizontal-axis and vertical-axis wind turbines.
| Horizontal-Axis | Vertical-Axis |
|---|---|
| Axis parallel to ground | Axis perpendicular to ground |
| Higher efficiency | Lower efficiency |
| Needs wind direction control | Works in any wind direction |
h. What is tidal energy? Name essential components of a tidal power plant.
Tidal energy is generated from the rise and fall of sea tides.
Components: barrage, sluice gates, turbines, generators, basin.
i. Explain the function of a switchgear.
Switchgear protects electrical equipment by controlling, isolating, and interrupting electrical circuits during faults or overloads.
j. Discuss peak load and base load power plants.
Base load plants operate continuously to meet minimum demand (e.g., thermal, nuclear).
Peak load plants operate during high demand periods (e.g., gas turbine, hydro).
SECTION B
(Attempt any three – solved answers provided for ALL)
2(a). Layout of modern coal-based thermal power plant & four main circuits
Main circuits:
Coal and Ash Circuit – coal handling, combustion, ash disposal
Air and Gas Circuit – air supply and flue gas exhaust
Feed Water and Steam Circuit – steam generation and condensation
Cooling Water Circuit – cooling of condenser
(Neat labeled diagram to be drawn in exam)
2(b). Classification of hydroelectric power plants & pumped storage plant
Classification: Run-of-river
Storage plant Pumped storage plant
Pumped storage plant:
Water is pumped to upper reservoir during low demand and released during peak demand to generate power.
2(c). Working of BWR and difference from PWR
BWR (Boiling Water Reactor): Water boils directly in reactor core and steam drives turbine.
Difference from PWR:
| BWR | PWR |
|---|---|
| Steam directly to turbine | Separate steam generator |
| Lower pressure | Higher pressure |
| Simpler design | More complex |
2(d). Working principle of fuel cell & applications
Fuel cells convert chemical energy directly into electrical energy using electrochemical reactions.
Applications: Spacecraft
Electric vehicles Backup power systems
2(e). Types of tariffs
Types: Simple tariff
Flat rate tariff Block rate tariff
Two-part tariff
Two-part tariff:
Includes fixed charges + running charges.
SECTION C
3(a). Rankine cycle numerical (conceptual solution)
Given: Inlet pressure = 35 bar (saturated steam)
Exhaust pressure = 0.2 bar Mass flow rate = 9.5 kg/s
Steps: Find properties from steam tables
Calculate pump work Calculate turbine work
Determine Rankine efficiency Calculate condenser heat flow
Find dryness fraction at turbine exit
(All calculations to be shown step-wise using steam tables in exam)
3(b). Factors for site selection of steam power plant
Factors include: Availability of fuel
Water supply Transportation facilities
Load center proximity Environmental considerations
Land availability
4(a). Layout of hydroelectric power plant
Main components: Dam
Reservoir Penstock
Turbine Generator
Draft tube
Each component helps convert hydraulic energy into electrical energy.
4(b). Combined cycle power plant
Combined cycle plant uses gas turbine exhaust heat to produce steam for steam turbine, increasing overall efficiency.
5(a). Nuclear power plant – parts, advantages & disadvantages
Parts: Reactor
Moderator Control rods
Steam generator Turbine & generator
Advantages: High energy density
Low fuel cost No greenhouse gas emission
Disadvantages: Radioactive waste
High initial cost Safety concerns
6(a). Concentrating collectors & comparison
Types: Parabolic trough
Parabolic dish Heliostat field
Advantages over flat plate:
Higher temperature Higher efficiency
Disadvantages: Costly
Requires tracking system
6(b). Vapour-dominated geothermal system
Uses dry steam directly from earth to run turbine.
Advantages: renewable, low emissions Disadvantages: site-specific, corrosion issues
7(a). Load curve numerical Given load data, calculate:
Maximum demand Units generated per day
Average load Load factor
(Draw load curve and show step-wise calculations in exam)
7(b). Short notes
(a) Pollution from thermal plants:
Air pollution, ash disposal, thermal pollution. Controlled using ESPs, scrubbers, cooling towers.
(b) Protective electrical equipment:
Circuit breakers, relays, fuses, isolators ensure system safety.