Steam Engines objective questions with answers part6

Q1. Spontaneous combustion is a phenomenon in which
(A) all the fuel burns instantaneously producing high energy release
(B) fuel burns with less air
(C) coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combination of oxygen with coal
(D) explosion in furnace

Q2. The economiser is used in boilers to
(A) increase thermal efficiency of boiler
(B) economise on fuel
(C) extract heat from the exhaust flue gases
(D) increase flue gas temperature

Q3. An economiser in a boiler
(A) increases steam pressure
(B) increases steam flow
(C) decreases fuel consumption
(D) decreases steam pressure

Q4. Primary air is the air used to
(A) provide air around burners for obtaining optimum combustion
(B) transport and dry the coal
(C) convert CO (formed in lower zone of furnace) into C02 at higher zone
(D) air-delivered by forced draft fan

Q5. Sulphur content of fuels is very important to the plant operators because it
(A) has high heating value
(B) retards electric precipitation
(C) promotes complete combustion
(D) has highly corrosive effect

Q6. Presence of moisture in fuel oil would
(A) keep the burner tips cool
(B) aid in proper combustion
(C) cause sputtering, possibly extinguishing flame
(D) reduce flame length

Q7. Gusset stays in a boiler are provided to
(A) prevent the bulging of flat surfaces
(B) avoid explosion in furnace
(C) prevent leakage of hot flue gases
(D) support furnace freely from top

Q8. Water and sediment in fuel oil can be removed by
(A) heating the oil in the settling tanks
(B) cooling the oil in the settling tanks
(C) burning the oil
(D) suspension

Q9. Pour point of fuel oil is the
(A) lowest temperature at which oil will flow under set condition
(B) storage temperature
(C) temperature at which fuel is pumped through burners
(D) temperature at which oil is transported

Q10. Secondary air is the used to
(A) provide air around burners for obtaining optimum combustion
(B) transport and dry the coal
(C) convert CO (formed in lower zone of furnace) into C02 at higher zone
(D) air delivered by induced draft fan

Q11. The behaviour of coal in a furnace is determained by
(A) the content of sulphur
(B) the content of ash and heating value
(C) the proximate analysis
(D) the exact analysis

Q12. Pick up wrong statement about desired properties of a good fuel
(A) high calorific value
(B) produce minimum smoke and gases
(C) high ignition point
(D) economical

Q13. Sulphur in coal results in
(A) causing clinkering and slagging
(B) spontaneous combustion during coal storage
(C) facilitating ash precipitation
(D) All of these

Q14. Caking coals are those which
(A) form lumps or masses of coke
(B) burn freely
(C) show little or no fusing action
(D) burn completely

Q15. Green coal, in order to be burnt, must be
(A) heated sufficiently
(B) burnt in excess air
(C) heated to its ignition point
(D) burnt as powder

Q16. Tertiary air is the air used to
(A) provide air around burners for obtaining optimum combustion
(B) transport and dry the coal
(C) cool the scanners
(D) convert CO into C02 at higher zone.

Q17. The safety valve on boiler drum compared to safety valve on superheater is set at
(A) same value
(B) higher value
(C) lower value
(D) lower/higher depending on steam flow

Q18. Which is not correct statement about pulverised fuel firing
(A) high burning rate is possible
(B) heat release can be easily controlled
(C) fuel burns economically
(D) it is the best technique for burning high ash content fuel having low fusion ash

Q19. The three “T” for good combustion are
(A) temperature, time, and turbulance
(B) total air, true fuel, and turbulance
(C) thorough mixing, total air, and temperature
(D) total air, time, and temperature

Q20. Which is not correct statement about the function of furnace
(A) to provide proper conditions for con-tinuous complete combustion
(B) mix fuel with air and ignite
(C) separate ash from coal
(D) maintain heat supply to prepare and ignite the incoming fuel