(SEM VII) THEORY EXAMINATION 2023-24 POWER PLANT ENGINEERING

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.

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.

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:

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.