Multiple Choice Questions and Answers (MCQ) on Chemical Engineering Fuels and Combustion
01. Combustion of pulverised fuel
(A) Requires larger combustion chamber than rich gaseous fuel
(B) In a metallurgical furnace does not contaminate the product in the furnace by ash from fuel
(C) Suppresses the discharge of fine dust and grit into atmosphere
(D) All (A), (B) and (C)
Answer: Option A
02. Caking index of a coal is a measure of its
(A) Abradability
(B) Reactivity
(C) Agglutinating (binding) properties
(D) Porosity
Answer: Option C
03. White flue gas (resembling steam) coming out of the chimney of a thermal power plant indicates that the fuel used in the boiler furnace is
(A) Tar
(B) Coke oven gas
(C) Pitch
(D) Pulverised coke
Answer: Option B
04. Main component of sewage gas produced during anaerobic decomposition of organic waste (by suitable bacteria) during sewage disposal is
(A) H2
(B) CH4
(C) CO2
(D) N2
Answer: Option B
05. Spontaneous combustion of coal on storage results due to
(A) Inadequate ventilation
(B) Low temperature oxidation
(C) Storage in large heaps with small surface to volume ratio
(D) All (A), (B) and (C)
Answer: Option D
06. The shift conversion reaction taking place during water gas manufacture is given by
(A) C + H2O ↔ CO + H2
(B) C + 2H2O ↔ CO2 + 2H2
(C) CO + H2O ↔ CO2 + H2
(D) None of these
Answer: Option C
07. ‘Wobbe index’ is a characteristic of
(A) Solid fuels
(B) Gaseous fuels
(C) Liquid fuels
(D) Fat coals
Answer: Option B
08. __________ of the coal is the basis for Seylor’s coal classification.
(A) Proximate analysis
(B) Ultimate analysis
(C) Caking index
(D) Calorific value
Answer: Option B
09. In case of pulverised coal fired steam boiler, the secondary air serves the main purpose of
(A) Transportation of coal
(B) Drying of coal
(C) Combustion of coal by supplying it around the burner
(D) Preheating the primary air
Answer: Option C
10. The optimum percentage of excess air for combustion depends upon the __________ of the fuel.
(A) Type (solid, liquid or gaseous)
(B) Calorific value
(C) Sulphur content
(D) Ignition temperature
Answer: Option A
11. In flue gas analysis by Orsat’s apparatus, carbon monoxide is absorbed by
(A) Cuprous chloride
(B) Potassium hydroxide
(C) Alkaline pyrogallol solution
(D) None of these
Answer: Option A
12. Presence of free moisture in coal during its high temperature carbonisation
(A) Reduces the coking time
(B) Protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot oven walls
(C) Increases the loss of fine coal dust from the ovens when charging
(D) None of these
Answer: Option B
13. Washing of coal decreases its
(A) Caking index
(B) Mineral matter content
(C) Ash content
(D) Both (B) and (C)
Answer: Option B
14. In high temperature carbonisation of coal compared to low temperature carbonisation
(A) Yield of ammonia is less
(B) Aromatic content of tar is low
(C) H2 content in the coke oven gas is more
(D) Calorific value of the coke oven gas is lower
Answer: Option C
15. To avoid fire by spontaneous combustion of coal due to its low temperature oxidation, it should be stored in
(A) Shallow and small piles
(B) Fine sizes without the presence of any lump
(C) Closed space without any ventilation facility
(D) Large heaps with small surface to volume ratio
Answer: Option A
16. KOH solution used in Orsat apparatus absorbs
(A) CO2
(B) SO2
(C) Both (A) & (B)
(D) Neither (A) nor (B)
Answer: Option C
17. The gas which contributes maximum to the heating value of natural gas is
(A) CO
(B) CO2
(C) H2
(D) CH4
Answer: Option D
18. The heat of combustion of a fuel
(A) Is equal to the heat of formation
(B) Is always negative
(C) Can’t be known without calculating it
(D) Is always positive
Answer: Option B
19. Nitrogen in coal
(A) Is present upto 1-2%
(B) Comes from protein in parent vegetable matter
(C) Is recovered as ammonia during its carbonisation
(D) All (A), (B) and (C)
Answer: Option D
20. Which of the following is not increased by using preheated combustion air in place of ordinary air at room temperature?
(A) Calorific value of the fuel
(B) Flame temperature achieved
(C) Speed of combustion of fuel
(D) Heat transfer rate to the stock in the furnace
Answer: Option A
21.Calorific value of blast furnace gas is around __________ KCal/Nm3.
(A) 850
(B) 1800
(C) 4200
(D) 6500
Answer: Option A
22. Coking time in beehive coke oven is about
(A) 12 hours
(B) 2-3 days
(C) One week
(D) Two weeks
Answer: Option B
23. Ash content in the middling coal (a byproduct of coal washeries) in India ranges between __________ percent.
(A) 15 to 25
(B) 35 to 45
(C) 55 to 75
(D) 75
Answer: Option B
24. Which of the following would require least amount of secondary air for combustion?
(A) Coke breeze containing 25% ash and 2% volatile matter
(B) Anthracite containing 10% volatile matter and 8% ash
(C) Bituminous coal containing 20% ash and 25% volatile matter
(D) Semi-bituminous coal containing 25% ash and 20% volatile matter
Answer: Option A
25. Which of the following is not a binder for coal briquetting?
(A) Coal tar
(B) Bitumen
(C) Molasses
(D) None of these
Answer: Option D