Furnace Technology

61.Main gas valve in a gaseous fuel burner is a _________ valve.

1. Gate
2. Butterfly
3. Globe
4. None of these

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62.Maximum heat transfer in high temperature furnaces is by

1. Conduction
2. Convection
3. Radiation
4. Either (A), (B) or (C); depends on the type of furnace

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63.Maximum thermal efficiency of boiler may be about _________ percent.

1. 10
2. 25
3. 65
4. 90

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64.Means for giving direction to the circulation of gases in furnaces are

1. Fans
2. Arrangement of heating stock in the furnaces
3. Location of outlet ports and heating & combustion devices
4. All (A), (B) and (C)

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65.Metallic recuperators are not used for waste heat recovery, if the hot flue gas temperature is above _________ °C, because corrosion prevails at higher temperatures.

1. 350
2. 750
3. 1050
4. 1250

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66.Neutral atmosphere is maintained in a/an _________ furnace.

1. Cold rolled steel coil annealing
2. Open hearth
3. Soaking pit
4. Walking beam reheating

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67.Operation of blast furnace stove is based on the principles of a _________ furnace.

1. Regenerative
2. Recuperative
3. Both (A) and (B)
4. Neither (A) nor (B)

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68.Ostwald charts are meant for

1. Computing the excess/deficiency of combustion air
2. Calculation of flue gas temperature
3. Computation of flue gas analysis
4. None of these

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69.Out of the following fuels used in a furnace exhausting flue gas at a temperature of 600°C, the percentage stack loss will be maximum in case of complete combustion of

1. Furnace oil with air
2. Furnace oil with oxygen
3. Blast furnace gas with air
4. Blast furnace gas with oxygen

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