Fuels and Combustion

301.Presence of free moisture in coal is most disadvantageous during

1. Its pulverisation (as it requires more power)
2. Combustion of fire slacks on the grates
3. Handling (e.g. when emptying wagons)
4. None of these

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302.Presence of nitrogen in combustion air does not reduce the

1. Amount of heat liberated
2. Flame temperature
3. Flue gas temperature
4. Any of the above

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303.Presence of phosphorous in metallurgical coal

1. Is not undesirable
2. Reduces its calorific value
3. Badly affects the quality of steel
4. Increases its caking power

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304.Prime coking coal is always blended with medium or non- coking coal before carbonisation

1. To check against its excessive swelling during heating, which may exert high pressure and damage coke oven walls
2. Because, it alone produces unreactive coke
3. Both (A) and (B)
4. Neither (A) nor (B)

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305.Producer gas comprises mainly of

1. CO & N₂
2. CO & H₂
3. CO₂ & N₂
4. CO₂ & H₂

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306.Producer gas containing least amount of tar is produced by the

1. Partial combustion of coal
2. Partial combustion of large size (< 50 mm) coke
3. High pressure gasification of coal (e.g. in Lurgi gasifier)
4. Atmospheric pressure gasification of coal (e.g., in Kopper-Totzek gasifier)

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307.Proximate analysis of coal determines its _________ content.

1. Moisture, ash, sulphur & volatile matter
2. Moisture, volatile matter, ash & fixed carbon
3. Moisture, sulphur, nitrogen & fixed carbon
4. None of these

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308.Pulverised coal used in boiler firing need not have

1. Less moisture content
2. High fusion point of its ash
3. High bulk density
4. Lower ash content

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309.Pure carbon is completely burnt in oxygen. The flue gas analysis is 70%CO₂, 20%CO and 10%O₂. The percent excess oxygen used is

1. 20
2. 12.5
3. 0
4. 10

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310.Purity of coke means that, it is high in carbon and low in

1. Volatiles
2. Ash
3. Iron
4. Moisture

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