Fuels and Combustion

51.Artificial draught produced by a fan can be controlled by the

1. Speed of the fan
2. Damper
3. Variation in the pitch of the fan blades
4. All (A), (B) and (C)

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52.As the C/H ratio of the fuel increases, the amount of CO₂ formed on combustion _________ for the same percentage of excess air.

1. Decreases
2. Increases
3. Remain same
4. May increase or decrease depending on the type of fuel

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53.As the equilibrium moisture content of the coal increases, its

1. Calorific value increases
2. Swelling number decreases
3. Swelling number increases
4. Bulk density decreases

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54.Ash content in the coke produced from a coking coal having 20% ash may be around _________ percent.

1. 6
2. 12
3. 18
4. 24

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55.Ash content in the middling coal (a byproduct of coal washeries) in India ranges between _________ percent.

1. 15 to 25
2. 35 to 45
3. 55 to 75
4. 75

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56.Assam (India) coals suffers mainly from the disadvantage of high _________ content.

1. Ash
2. Volatile matter
3. Sulphur (4-6%)
4. Moisture

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57.Atomising steam to fuel oil ratio in a burner should be around

1. 0.5
2. 1.5
3. 2.5
4. 3.5

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58.Beehive coke oven

1. Facilitates by-products recovery
2. Takes 2-3 days for coking of coal but requires no external fuel for heating
3. Gives larger yield of coke (around 85%) as compared to by-product ovens
4. Produces coke with very poor strength

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59.Benzene is used

1. As a motor fuel
2. As an explosive
3. For making insecticides (e.g., DDT, BHC etc.), detergent & rubber (SBR)
4. As a perfume

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60.Benzol is used

1. As a motor fuel blend
2. For producing benzene, toluene & xylene by its distillation
3. Both (A) & (B)
4. Neither (A) nor (B)

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