Furnace Technology

101.The purpose of controlling the furnace atmosphere is to prevent surface attack by

1. Oxidation/scaling
2. Decarburising
3. Sulphur penetration
4. Either of the above

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102.The rate of scaling of furnace stock depends upon the

1. Temperature
2. Time
3. Nature of atmosphere
4. All (A), (B) and (C)

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103.The reason for excessive clinker formation in gas producers is the

1. Use of coal/coke containing a high % of fines and ash
2. Use of fuel having too low an ash fusion temperature
3. Development of hot spots in the fuel bed and an abnormally high rate of gasification
4. All (A), (B) and (C)

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104.The resistance furnace produces heat by the

1. Electric arc struck between electrodes and the charge
2. Flow of current through a heating element
3. Combination of induced current and skin effect
4. None of these

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105.The thermal efficiency of a steel slab reheating furnace (walking beam type) may be about _________ percent.

1. 15
2. 40
3. 70
4. 85

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106.The thermal efficiency of an air/fuel gas preheating recuperator may be as high as _________ percent.

1. 50
2. 65
3. 85
4. 99

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107.Thermal efficiency of a limestone calcination rotary kiln may be around _________ percent.

1. 20
2. 40
3. 65
4. 80

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108.Thermal efficiency of an open hearth furnace may be about _________ percent.

1. 5
2. 20
3. 50
4. 80

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109.Thermal efficiency of blast furnace stoves used for heating blast (air) may be about _________ percent.

1. 20
2. 40
3. 60
4. 80

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110.Thermal efficiency of furnaces can be improved by

1. Waste heat recovery from flue gas
2. Minimising heat losses from furnace walls
3. Maintaining proper draught
4. All (A), (B) and (C)

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