1st Class Power Engineer A3 Exam Questions
and Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a deaerator in a high-pressure
boiler system?
A. To increase steam pressure
B. To remove dissolved oxygen and carbon dioxide from feedwater
C. To reduce condensate temperature
D. To increase boiler blowdown frequency
Correct Answer: B. To remove dissolved oxygen and carbon dioxide
from feedwater
Rationale: A deaerator removes dissolved gases, primarily oxygen and
carbon dioxide, from boiler feedwater. These gases can cause severe
corrosion of boiler tubes, economizers, and steam piping. The
deaerator also preheats feedwater, improving thermal efficiency and
reducing thermal shock to the boiler.
, 2. Which boiler component primarily recovers heat from flue gases
to improve efficiency?
A. Steam drum
B. Mud drum
C. Economizer
D. Blowdown separator
Correct Answer: C. Economizer
Rationale: An economizer captures waste heat from flue gases and
transfers it to incoming feedwater before it enters the boiler. This
reduces fuel consumption, improves overall boiler efficiency, and
lowers stack temperatures.
3. The critical pressure of water is approximately:
A. 1 MPa
B. 10 MPa
C. 22.1 MPa
D. 50 MPa
Correct Answer: C. 22.1 MPa
Rationale: Water reaches its critical point at approximately 22.1 MPa
(3206 psi) and 374°C. Above this pressure, there is no distinct
,boundary between liquid and vapor, making supercritical boiler
operation possible.
4. Superheated steam differs from saturated steam because it:
A. Contains moisture
B. Exists at a temperature above its saturation temperature at the same
pressure
C. Has lower energy content
D. Always has lower pressure
Correct Answer: B. Exists at a temperature above its saturation
temperature at the same pressure
Rationale: Superheated steam is heated beyond its saturation
temperature without increasing pressure. It contains more energy,
minimizes condensation in turbines, and improves efficiency in power
generation.
5. A boiler safety valve should:
A. Be isolated during startup
B. Be blocked open during testing
, C. Open automatically when pressure exceeds its set point
D. Operate only manually
Correct Answer: C. Open automatically when pressure exceeds its set
point
Rationale: Safety valves protect boilers from dangerous overpressure
conditions by automatically releasing steam when pressure exceeds
the predetermined set point. They are among the most critical safety
devices on a boiler.
6. What is the primary purpose of continuous blowdown?
A. Increase steam pressure
B. Remove dissolved solids from boiler water
C. Increase feedwater flow
D. Reduce burner firing rate
Correct Answer: B. Remove dissolved solids from boiler water
Rationale: Continuous blowdown removes water containing
concentrated dissolved solids from the boiler. This helps maintain
proper water chemistry, minimizes scale formation, and improves
steam purity.
and Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a deaerator in a high-pressure
boiler system?
A. To increase steam pressure
B. To remove dissolved oxygen and carbon dioxide from feedwater
C. To reduce condensate temperature
D. To increase boiler blowdown frequency
Correct Answer: B. To remove dissolved oxygen and carbon dioxide
from feedwater
Rationale: A deaerator removes dissolved gases, primarily oxygen and
carbon dioxide, from boiler feedwater. These gases can cause severe
corrosion of boiler tubes, economizers, and steam piping. The
deaerator also preheats feedwater, improving thermal efficiency and
reducing thermal shock to the boiler.
, 2. Which boiler component primarily recovers heat from flue gases
to improve efficiency?
A. Steam drum
B. Mud drum
C. Economizer
D. Blowdown separator
Correct Answer: C. Economizer
Rationale: An economizer captures waste heat from flue gases and
transfers it to incoming feedwater before it enters the boiler. This
reduces fuel consumption, improves overall boiler efficiency, and
lowers stack temperatures.
3. The critical pressure of water is approximately:
A. 1 MPa
B. 10 MPa
C. 22.1 MPa
D. 50 MPa
Correct Answer: C. 22.1 MPa
Rationale: Water reaches its critical point at approximately 22.1 MPa
(3206 psi) and 374°C. Above this pressure, there is no distinct
,boundary between liquid and vapor, making supercritical boiler
operation possible.
4. Superheated steam differs from saturated steam because it:
A. Contains moisture
B. Exists at a temperature above its saturation temperature at the same
pressure
C. Has lower energy content
D. Always has lower pressure
Correct Answer: B. Exists at a temperature above its saturation
temperature at the same pressure
Rationale: Superheated steam is heated beyond its saturation
temperature without increasing pressure. It contains more energy,
minimizes condensation in turbines, and improves efficiency in power
generation.
5. A boiler safety valve should:
A. Be isolated during startup
B. Be blocked open during testing
, C. Open automatically when pressure exceeds its set point
D. Operate only manually
Correct Answer: C. Open automatically when pressure exceeds its set
point
Rationale: Safety valves protect boilers from dangerous overpressure
conditions by automatically releasing steam when pressure exceeds
the predetermined set point. They are among the most critical safety
devices on a boiler.
6. What is the primary purpose of continuous blowdown?
A. Increase steam pressure
B. Remove dissolved solids from boiler water
C. Increase feedwater flow
D. Reduce burner firing rate
Correct Answer: B. Remove dissolved solids from boiler water
Rationale: Continuous blowdown removes water containing
concentrated dissolved solids from the boiler. This helps maintain
proper water chemistry, minimizes scale formation, and improves
steam purity.
