2nd Class Power Engineer B1 Exam Questions
and Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. In a water-tube boiler, the primary advantage over a fire-tube
boiler is:
A. Lower pressure capability
B. Lower steam production
C. Higher pressure and higher steam generation capacity
D. Lower construction cost
Answer: C
Rationale: Water-tube boilers circulate water through tubes heated
externally by combustion gases. This design allows them to safely
withstand much higher pressures and generate large quantities of
steam, making them suitable for industrial power generation. Fire-
tube boilers are generally limited to lower pressures and capacities.
2. The primary purpose of a deaerator is to:
A. Increase boiler pressure
, B. Remove suspended solids
C. Remove dissolved oxygen and carbon dioxide from feedwater
D. Increase water hardness
Answer: C
Rationale: Dissolved oxygen and carbon dioxide contribute
significantly to corrosion within boilers and condensate systems. A
deaerator heats feedwater while venting dissolved gases, extending
equipment life and improving boiler efficiency.
3. Which boiler safety device prevents excessive pressure?
A. Blowdown valve
B. Feedwater regulator
C. Safety valve
D. Check valve
Answer: C
Rationale: Safety valves automatically open when boiler pressure
exceeds the set limit, protecting the boiler from catastrophic
overpressure. They are among the most critical safety devices on any
pressure vessel.
, 4. Boiler blowdown is primarily performed to:
A. Increase steam pressure
B. Cool the boiler
C. Control dissolved and suspended solids
D. Reduce fuel consumption
Answer: C
Rationale: Blowdown removes concentrated impurities from the boiler
water, preventing scale formation, foaming, and carryover while
maintaining acceptable water chemistry.
5. Scale formation inside boiler tubes primarily results in:
A. Improved heat transfer
B. Lower fuel consumption
C. Reduced heat transfer and possible overheating
D. Increased boiler efficiency
Answer: C
Rationale: Scale acts as an insulating barrier, reducing heat transfer
from combustion gases to water. This causes tube metal temperatures
to rise, potentially resulting in tube failure and increased fuel usage.
, 6. The economizer is designed to:
A. Heat combustion air
B. Cool flue gases
C. Recover waste heat to preheat feedwater
D. Produce superheated steam
Answer: C
Rationale: Economizers improve boiler efficiency by capturing heat
from flue gases before they exit the stack. This recovered energy raises
feedwater temperature, reducing fuel required to generate steam.
7. The function of a superheater is to:
A. Produce saturated steam
B. Condense steam
C. Increase steam temperature above saturation
D. Remove impurities
Answer: C
Rationale: A superheater adds sensible heat to saturated steam
without increasing pressure. Superheated steam improves turbine
efficiency and reduces moisture formation during expansion.
and Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. In a water-tube boiler, the primary advantage over a fire-tube
boiler is:
A. Lower pressure capability
B. Lower steam production
C. Higher pressure and higher steam generation capacity
D. Lower construction cost
Answer: C
Rationale: Water-tube boilers circulate water through tubes heated
externally by combustion gases. This design allows them to safely
withstand much higher pressures and generate large quantities of
steam, making them suitable for industrial power generation. Fire-
tube boilers are generally limited to lower pressures and capacities.
2. The primary purpose of a deaerator is to:
A. Increase boiler pressure
, B. Remove suspended solids
C. Remove dissolved oxygen and carbon dioxide from feedwater
D. Increase water hardness
Answer: C
Rationale: Dissolved oxygen and carbon dioxide contribute
significantly to corrosion within boilers and condensate systems. A
deaerator heats feedwater while venting dissolved gases, extending
equipment life and improving boiler efficiency.
3. Which boiler safety device prevents excessive pressure?
A. Blowdown valve
B. Feedwater regulator
C. Safety valve
D. Check valve
Answer: C
Rationale: Safety valves automatically open when boiler pressure
exceeds the set limit, protecting the boiler from catastrophic
overpressure. They are among the most critical safety devices on any
pressure vessel.
, 4. Boiler blowdown is primarily performed to:
A. Increase steam pressure
B. Cool the boiler
C. Control dissolved and suspended solids
D. Reduce fuel consumption
Answer: C
Rationale: Blowdown removes concentrated impurities from the boiler
water, preventing scale formation, foaming, and carryover while
maintaining acceptable water chemistry.
5. Scale formation inside boiler tubes primarily results in:
A. Improved heat transfer
B. Lower fuel consumption
C. Reduced heat transfer and possible overheating
D. Increased boiler efficiency
Answer: C
Rationale: Scale acts as an insulating barrier, reducing heat transfer
from combustion gases to water. This causes tube metal temperatures
to rise, potentially resulting in tube failure and increased fuel usage.
, 6. The economizer is designed to:
A. Heat combustion air
B. Cool flue gases
C. Recover waste heat to preheat feedwater
D. Produce superheated steam
Answer: C
Rationale: Economizers improve boiler efficiency by capturing heat
from flue gases before they exit the stack. This recovered energy raises
feedwater temperature, reducing fuel required to generate steam.
7. The function of a superheater is to:
A. Produce saturated steam
B. Condense steam
C. Increase steam temperature above saturation
D. Remove impurities
Answer: C
Rationale: A superheater adds sensible heat to saturated steam
without increasing pressure. Superheated steam improves turbine
efficiency and reduces moisture formation during expansion.
