LA STEAM ENGINEER| 91 QUESTIONS| WITH COMPLETE
SOLUTIONS | WITH RATIONALES
1. What is the primary function of a desuperheater in a boiler?
A) Increase steam pressure
B) Control superheated steam temperature
C) Reduce flue gas emissions
D) Improve combustion efficiency
Answer: B) Control superheated steam temperature
Rationale: A desuperheater reduces steam temperature by injecting water, ensuring safe and efficient
operation.
2. Why are economizers finned?
A) To reduce maintenance costs
B) To increase the rate of heat transfer
C) To prevent corrosion
D) To decrease flue gas velocity
Answer: B) To increase the rate of heat transfer
Rationale: Fins expand the surface area, improving heat absorption from flue gases.
3. How is heat primarily transferred in a surface condenser?
A) Radiation
B) Conduction
C) Convection
D) Advection
Answer: B) Conduction
Rationale: Heat moves from steam to cooling water through the metal tubes via conduction.
4. What is an unfired pressure vessel used to transfer heat between substances called?
,A) Superheater
B) Feedwater heater
C) Combustion chamber
D) Steam drum
Answer: B) Feedwater heater
Rationale: It preheats feedwater using steam extraction, improving boiler efficiency.
5. What is the main purpose of a boiler economizer?
A) Increase combustion air temperature
B) Recover heat from flue gas
C) Reduce steam pressure
D) Filter particulate matter
Answer: B) Recover heat from flue gas
Rationale: Economizers capture waste heat to preheat feedwater.
6. Why is a deaerator used in boiler systems?
A) To increase water pressure
B) To eliminate non-condensable gases (O₂ & CO₂)
C) To reduce steam temperature
D) To filter impurities
Answer: B) To eliminate non-condensable gases (O₂ & CO₂)
Rationale: Removing gases prevents corrosion and improves efficiency.
7. Why is superheated steam more efficient?
A) It has higher density
B) Temperature & total heat content are increased
C) It reduces pump workload
D) It prevents scaling
Answer: B) Temperature & total heat content are increased
Rationale: Superheating adds energy without raising pressure, improving work output.
8. Why does a boiler feed pump have a discharge check valve?
, A) To prevent backflow
B) To permit fast startup by leaving the discharge valve open
C) To regulate water temperature
D) To reduce cavitation
Answer: B) To permit fast startup by leaving the discharge valve open
Rationale: The check valve prevents backflow while allowing immediate operation.
9. What indicates excessive fireside deposits in a superheater?
A) Increased steam pressure
B) Decreased superheater outlet temperature
C) Higher flue gas oxygen levels
D) Reduced feedwater flow
Answer: B) Decreased superheater outlet temperature
Rationale: Insulation from deposits reduces heat transfer efficiency.
10. Why is the superheater safety valve set to release before the drum safety valve?
A) To reduce steam pressure faster
B) To ensure flow through the superheater
C) To prevent water hammer
D) To improve combustion
Answer: B) To ensure flow through the superheater
Rationale: Prevents overheating by maintaining steam flow during pressure surges.
11. What is the purpose of a steam trap?
A) To filter steam impurities
B) To drain water and air
C) To increase steam pressure
D) To measure steam quality
Answer: B) To drain water and air
Rationale: Traps remove condensate while retaining steam.
12. What closes an impulse steam trap after opening?
SOLUTIONS | WITH RATIONALES
1. What is the primary function of a desuperheater in a boiler?
A) Increase steam pressure
B) Control superheated steam temperature
C) Reduce flue gas emissions
D) Improve combustion efficiency
Answer: B) Control superheated steam temperature
Rationale: A desuperheater reduces steam temperature by injecting water, ensuring safe and efficient
operation.
2. Why are economizers finned?
A) To reduce maintenance costs
B) To increase the rate of heat transfer
C) To prevent corrosion
D) To decrease flue gas velocity
Answer: B) To increase the rate of heat transfer
Rationale: Fins expand the surface area, improving heat absorption from flue gases.
3. How is heat primarily transferred in a surface condenser?
A) Radiation
B) Conduction
C) Convection
D) Advection
Answer: B) Conduction
Rationale: Heat moves from steam to cooling water through the metal tubes via conduction.
4. What is an unfired pressure vessel used to transfer heat between substances called?
,A) Superheater
B) Feedwater heater
C) Combustion chamber
D) Steam drum
Answer: B) Feedwater heater
Rationale: It preheats feedwater using steam extraction, improving boiler efficiency.
5. What is the main purpose of a boiler economizer?
A) Increase combustion air temperature
B) Recover heat from flue gas
C) Reduce steam pressure
D) Filter particulate matter
Answer: B) Recover heat from flue gas
Rationale: Economizers capture waste heat to preheat feedwater.
6. Why is a deaerator used in boiler systems?
A) To increase water pressure
B) To eliminate non-condensable gases (O₂ & CO₂)
C) To reduce steam temperature
D) To filter impurities
Answer: B) To eliminate non-condensable gases (O₂ & CO₂)
Rationale: Removing gases prevents corrosion and improves efficiency.
7. Why is superheated steam more efficient?
A) It has higher density
B) Temperature & total heat content are increased
C) It reduces pump workload
D) It prevents scaling
Answer: B) Temperature & total heat content are increased
Rationale: Superheating adds energy without raising pressure, improving work output.
8. Why does a boiler feed pump have a discharge check valve?
, A) To prevent backflow
B) To permit fast startup by leaving the discharge valve open
C) To regulate water temperature
D) To reduce cavitation
Answer: B) To permit fast startup by leaving the discharge valve open
Rationale: The check valve prevents backflow while allowing immediate operation.
9. What indicates excessive fireside deposits in a superheater?
A) Increased steam pressure
B) Decreased superheater outlet temperature
C) Higher flue gas oxygen levels
D) Reduced feedwater flow
Answer: B) Decreased superheater outlet temperature
Rationale: Insulation from deposits reduces heat transfer efficiency.
10. Why is the superheater safety valve set to release before the drum safety valve?
A) To reduce steam pressure faster
B) To ensure flow through the superheater
C) To prevent water hammer
D) To improve combustion
Answer: B) To ensure flow through the superheater
Rationale: Prevents overheating by maintaining steam flow during pressure surges.
11. What is the purpose of a steam trap?
A) To filter steam impurities
B) To drain water and air
C) To increase steam pressure
D) To measure steam quality
Answer: B) To drain water and air
Rationale: Traps remove condensate while retaining steam.
12. What closes an impulse steam trap after opening?
