1st Class Power Engineer A4 Exam Questions
and Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. In a high-pressure utility boiler, the primary purpose of a
superheater is to:
A. Increase feedwater temperature
B. Increase steam temperature above saturation
C. Remove dissolved gases
D. Reduce furnace pressure
Rationale: A superheater raises the temperature of saturated steam
beyond its saturation point without increasing its pressure.
Superheated steam improves turbine efficiency, minimizes moisture
formation during expansion, and reduces blade erosion in turbines.
This makes it essential in high-pressure power generation systems.
2. Which boiler component primarily removes suspended solids from
boiler water?
A. Economizer
,B. Air preheater
C. Blowdown system
D. Steam separator
Rationale: Blowdown removes concentrated impurities and suspended
solids from the boiler. Continuous and intermittent blowdown help
maintain acceptable water chemistry, preventing scale formation,
corrosion, and carryover while ensuring efficient heat transfer.
3. What is the principal purpose of an economizer?
A. Increase furnace draft
B. Recover waste heat to preheat feedwater
C. Increase steam pressure
D. Condense exhaust steam
Rationale: An economizer recovers heat from flue gases that would
otherwise be lost up the stack. This recovered energy heats incoming
feedwater, improving boiler efficiency, reducing fuel consumption, and
lowering operating costs.
4. Which type of pump is most commonly used for high-pressure
boiler feedwater service?
A. Gear pump
,B. Multistage centrifugal pump
C. Diaphragm pump
D. Rotary vane pump
Rationale: Multistage centrifugal pumps are capable of producing the
high pressures required to overcome boiler pressure. Multiple
impellers increase pressure progressively while maintaining reliable
continuous flow.
5. Scale formation inside boiler tubes primarily results in:
A. Improved heat transfer
B. Reduced heat transfer and overheating
C. Lower fuel consumption
D. Increased steam quality
Rationale: Scale acts as an insulating layer that restricts heat transfer
from combustion gases to water. Tube metal temperatures rise
significantly, increasing the likelihood of tube deformation and failure.
6. A deaerator primarily removes:
A. Fuel impurities
B. Dissolved oxygen and carbon dioxide
, C. Steam moisture
D. Lubricating oil
Rationale: Dissolved oxygen and carbon dioxide cause corrosion in
boilers and piping. A deaerator heats feedwater near saturation and
vents dissolved gases, protecting the boiler system from corrosion.
7. What instrument measures furnace draft?
A. Bourdon gauge
B. Rotameter
C. Draft gauge (manometer)
D. Tachometer
Rationale: A draft gauge measures the slight negative or positive
pressure inside the furnace relative to atmospheric pressure. Proper
draft ensures adequate combustion air and safe flue gas removal.
8. Which combustion condition generally produces the highest boiler
efficiency?
A. Excessive excess air
B. Insufficient combustion air
C. Proper fuel-air ratio with minimal excess air
and Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. In a high-pressure utility boiler, the primary purpose of a
superheater is to:
A. Increase feedwater temperature
B. Increase steam temperature above saturation
C. Remove dissolved gases
D. Reduce furnace pressure
Rationale: A superheater raises the temperature of saturated steam
beyond its saturation point without increasing its pressure.
Superheated steam improves turbine efficiency, minimizes moisture
formation during expansion, and reduces blade erosion in turbines.
This makes it essential in high-pressure power generation systems.
2. Which boiler component primarily removes suspended solids from
boiler water?
A. Economizer
,B. Air preheater
C. Blowdown system
D. Steam separator
Rationale: Blowdown removes concentrated impurities and suspended
solids from the boiler. Continuous and intermittent blowdown help
maintain acceptable water chemistry, preventing scale formation,
corrosion, and carryover while ensuring efficient heat transfer.
3. What is the principal purpose of an economizer?
A. Increase furnace draft
B. Recover waste heat to preheat feedwater
C. Increase steam pressure
D. Condense exhaust steam
Rationale: An economizer recovers heat from flue gases that would
otherwise be lost up the stack. This recovered energy heats incoming
feedwater, improving boiler efficiency, reducing fuel consumption, and
lowering operating costs.
4. Which type of pump is most commonly used for high-pressure
boiler feedwater service?
A. Gear pump
,B. Multistage centrifugal pump
C. Diaphragm pump
D. Rotary vane pump
Rationale: Multistage centrifugal pumps are capable of producing the
high pressures required to overcome boiler pressure. Multiple
impellers increase pressure progressively while maintaining reliable
continuous flow.
5. Scale formation inside boiler tubes primarily results in:
A. Improved heat transfer
B. Reduced heat transfer and overheating
C. Lower fuel consumption
D. Increased steam quality
Rationale: Scale acts as an insulating layer that restricts heat transfer
from combustion gases to water. Tube metal temperatures rise
significantly, increasing the likelihood of tube deformation and failure.
6. A deaerator primarily removes:
A. Fuel impurities
B. Dissolved oxygen and carbon dioxide
, C. Steam moisture
D. Lubricating oil
Rationale: Dissolved oxygen and carbon dioxide cause corrosion in
boilers and piping. A deaerator heats feedwater near saturation and
vents dissolved gases, protecting the boiler system from corrosion.
7. What instrument measures furnace draft?
A. Bourdon gauge
B. Rotameter
C. Draft gauge (manometer)
D. Tachometer
Rationale: A draft gauge measures the slight negative or positive
pressure inside the furnace relative to atmospheric pressure. Proper
draft ensures adequate combustion air and safe flue gas removal.
8. Which combustion condition generally produces the highest boiler
efficiency?
A. Excessive excess air
B. Insufficient combustion air
C. Proper fuel-air ratio with minimal excess air
