Furnace Technology

21.Ceramic recuperators compared to metallic recuperators for the same duty

1. Are lighter
2. Occupy more space
3. Are less costly
4. Have higher pressure differential between flue gas & air side

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22.Circulation of gases in furnace is caused by the

1. Change in volume during a change of temperature
2. Difference in density between hot and cold gases
3. Furnace pressure in conjunction with draft in flues
4. All (A), (B) and (C)

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23.Coke ovens in steel plant are heated by

1. Electricity
2. Blast furnace gas/mixed gas
3. Coke oven gas
4. Both (B) and (C)

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24.Combustion of fuel in a furnace with oxygen enriched air results in higher

1. Flue gas volume
2. Flame temperature
3. Fuel consumption
4. Stack loss

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25.Combustion of furnace oil in a furnace (soaking pit) with preheated combustion air at 400°C results in saving of about _________ percent furnace oil as compared to its combustion with atmospheric air, if the flue gas outlet temperature from the soaking pit is 1200°C.

1. 5
2. 60
3. 20
4. 40

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26.Dampers are located

1. Before the I.D fan
2. After the I.D. fan
3. Near the top of the chimney
4. Anywhere after the I.D. fan

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27.Decarburisation of steel

1. Is the removal of carbon from iron carbide (Fe3C)
2. Affects its crystalline structure
3. Is favoured by CO₂
4. All (A), (B) and (C)

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28.Design of waste heat boiler for recovery of waste heat from furnace gases depends upon the

1. Quantity & temperature of waste gas
2. Dust concentration & nature of dust in waste gas
3. Corrosive nature of the waste gas
4. All (A), (B) and (C)

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29.Example of an indirectly heated furnace is

1. Hood annealing furnace
2. Muffle furnace
3. Both (A) and (B)
4. Neither (A) nor (B)

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30.Flue gas outlet temperature from the chimney of any furnace should be ideally about _________ °C.

1. 50
2. 100
3. 150
4. 250

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