Power Engineer Second Class Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. Which device is primarily responsible for maintaining boiler water level
automatically in a high-pressure steam boiler?
A. Pressure reducing valve
B. Feedwater level control system
C. Safety relief valve
D. Steam separator
Rationale: The feedwater level control system continuously monitors boiler
water level and regulates feedwater flow to maintain a safe operating
level. Proper water level prevents overheating of boiler tubes and ensures
efficient steam production.
2. What is the primary purpose of a deaerator in a steam plant?
A. Increase steam pressure
B. Remove suspended solids from feedwater
C. Remove dissolved oxygen and carbon dioxide from feedwater
D. Cool condensate before pumping
,Rationale: A deaerator removes dissolved gases such as oxygen and carbon
dioxide, which can cause corrosion in boilers, piping, and condensate
systems.
3. Which boiler component transfers heat directly from combustion gases
to water?
A. Steam drum
B. Economizer
C. Water tubes
D. Blowdown separator
Rationale: Water tubes contain water while hot combustion gases flow
around them, transferring heat efficiently to generate steam in water-tube
boilers.
4. Boiler blowdown is primarily performed to:
A. Increase steam pressure
B. Reduce combustion air
C. Control dissolved solids and sludge accumulation
D. Improve burner ignition
Rationale: Blowdown removes concentrated dissolved solids and
sediment, preventing scale formation, foaming, and carryover while
maintaining proper water chemistry.
5. A safety valve on a boiler is designed to:
A. Regulate steam temperature
B. Control feedwater flow
C. Prevent vacuum formation
D. Prevent excessive boiler pressure
, Rationale: Safety valves automatically release steam when pressure
exceeds the set point, protecting the boiler from dangerous overpressure
conditions.
6. The economizer improves boiler efficiency by:
A. Heating combustion air
B. Heating feedwater using waste flue gas heat
C. Cooling exhaust gases
D. Separating moisture from steam
Rationale: An economizer captures waste heat from flue gases to preheat
feedwater, reducing fuel consumption and improving overall thermal
efficiency.
7. What is the purpose of a superheater?
A. Reduce steam pressure
B. Raise steam temperature above saturation
C. Remove moisture from condensate
D. Increase feedwater flow
Rationale: A superheater adds additional heat to saturated steam,
increasing its temperature without increasing pressure, making it more
suitable for turbines and industrial processes.
8. Which combustion condition generally produces the highest carbon
monoxide levels?
A. Excess combustion air
B. Insufficient combustion air
C. Proper air-fuel ratio
D. High feedwater temperature
Rationale: Insufficient oxygen causes incomplete combustion, resulting in
elevated carbon monoxide production and reduced combustion efficiency.
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. Which device is primarily responsible for maintaining boiler water level
automatically in a high-pressure steam boiler?
A. Pressure reducing valve
B. Feedwater level control system
C. Safety relief valve
D. Steam separator
Rationale: The feedwater level control system continuously monitors boiler
water level and regulates feedwater flow to maintain a safe operating
level. Proper water level prevents overheating of boiler tubes and ensures
efficient steam production.
2. What is the primary purpose of a deaerator in a steam plant?
A. Increase steam pressure
B. Remove suspended solids from feedwater
C. Remove dissolved oxygen and carbon dioxide from feedwater
D. Cool condensate before pumping
,Rationale: A deaerator removes dissolved gases such as oxygen and carbon
dioxide, which can cause corrosion in boilers, piping, and condensate
systems.
3. Which boiler component transfers heat directly from combustion gases
to water?
A. Steam drum
B. Economizer
C. Water tubes
D. Blowdown separator
Rationale: Water tubes contain water while hot combustion gases flow
around them, transferring heat efficiently to generate steam in water-tube
boilers.
4. Boiler blowdown is primarily performed to:
A. Increase steam pressure
B. Reduce combustion air
C. Control dissolved solids and sludge accumulation
D. Improve burner ignition
Rationale: Blowdown removes concentrated dissolved solids and
sediment, preventing scale formation, foaming, and carryover while
maintaining proper water chemistry.
5. A safety valve on a boiler is designed to:
A. Regulate steam temperature
B. Control feedwater flow
C. Prevent vacuum formation
D. Prevent excessive boiler pressure
, Rationale: Safety valves automatically release steam when pressure
exceeds the set point, protecting the boiler from dangerous overpressure
conditions.
6. The economizer improves boiler efficiency by:
A. Heating combustion air
B. Heating feedwater using waste flue gas heat
C. Cooling exhaust gases
D. Separating moisture from steam
Rationale: An economizer captures waste heat from flue gases to preheat
feedwater, reducing fuel consumption and improving overall thermal
efficiency.
7. What is the purpose of a superheater?
A. Reduce steam pressure
B. Raise steam temperature above saturation
C. Remove moisture from condensate
D. Increase feedwater flow
Rationale: A superheater adds additional heat to saturated steam,
increasing its temperature without increasing pressure, making it more
suitable for turbines and industrial processes.
8. Which combustion condition generally produces the highest carbon
monoxide levels?
A. Excess combustion air
B. Insufficient combustion air
C. Proper air-fuel ratio
D. High feedwater temperature
Rationale: Insufficient oxygen causes incomplete combustion, resulting in
elevated carbon monoxide production and reduced combustion efficiency.
