Furnace Technology

111.Thickness of stock does not affect the fuel economy of furnaces, if the material to be heated is of

1. Low emissivity
2. High thermal conductivity
3. Both (A) and (B)
4. Neither (A) nor (B)

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112.To reduce the stack loss, heat recovery from flue gas can be done by

1. Preheating of cold stock
2. Preheating of combustion air
3. Steam generation in waste heat boilers
4. All (A), (B) and (C)

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113.Turn down ratio of a burner

1. Should be as low as possible i.e., 1 : 2
2. Should be 1:1 for a batch type furnace
3. Is the ratio of maximum to minimum permissible heat input rates
4. Is normally much more for a continuous furnace as compared to a batch furnace

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114.Turndown ratio of a burner gives an idea of the _________ in the furnace.

1. Range of fuel firing rates
2. Volume of the combustion chamber
3. Maximum heat input rate only
4. Minimum heat input rate only

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115.Unit of furnace loading is

1. Ton stock/hr/m² hearth area
2. Ton stock/hr
3. Ton stock/m² hearth area
4. Both (B) and (C)

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116.Use of pulverised coal in boilers provides

1. Higher calorific value
2. Better combustion
3. Smokeless burning
4. Less erosion on furnace wall

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117.Very high pressure boilers are usually _________ boilers.

1. Fire tube
2. Water tube
3. Waste heat
4. Natural circulation

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118.Waste heat from the outgoing flue gases in a thermal power plant is recovered by a/an

1. Economiser
2. Steam superheater
3. Air preheater
4. All (A), (B) and (C)

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119.Which furnace employs an I.D. fan for the removal of flue gases from the furnace?

1. Coke oven
2. Blast furnace stoves
3. Beehive coke oven
4. High pressure boiler

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120.Which furnace employs preheating, heating and soaking zones?

1. Soaking pit
2. Reheating furnace
3. Open hearth furnace
4. Cupola

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