Furnace Technology

70.Overall thermal efficiency of a lumpy coal fired suitably designed heating furnace, if operated & maintained properly may be about _________ percent.

  1. 42278
  2. 25-30
  3. 45-50
  4. 65-70

Correct answer: (B)
25-30

71.Overfire burning in a furnace is a phenomenon characterised by

  1. Supply of excess fuel
  2. Supply of excess air
  3. Burning carbon monoxide and other incombustible in upper zone of furnace by supplying more air
  4. None of these

Correct answer: (C)
Burning carbon monoxide and other incombustible in upper zone of furnace by supplying more air

72.Oxygen percentage in the flue gas coming out of a gaseous fuel fired furnace should be ideally about _________ percent.

  1. < 2
  2. < 5
  3. < 8
  4. < 10

Correct answer: (A)
< 2

73.Pick out the wrong statement.

  1. Addition of methane to the furnace atmosphere reduces decarburising by hydrogen
  2. Nitrogen in presence of steam decor-burises high carbon steel, whereas hydrocarbon gases carburise the surface of steel at annealing temperatures
  3. Active nitrogen (formed by cracking ammonia at the metal surface) cause nitride formation with increase in surface hardness
  4. None of these

Correct answer: (D)
None of these

74.Pot furnace which is either regenerative or recuperative, is used in the manufacture of

  1. Glass
  2. Stainless steel
  3. Potteries
  4. Refractory bricks

Correct answer: (A)
Glass

75.Presence of SO2 in furnace gases attacks the ferrous metal by way of

  1. Accelerating the rate of scaling
  2. Causing metal embrittlement
  3. Attacking the grain boundaries; particularly severe on low carbon and nickel bearing steels at high temperature
  4. All (A), (B) and (C)

Correct answer: (D)
All (A), (B) and (C)

76.Protective gas used in the annealing furnace for steel coil comprises of

  1. 95% N2 + 5% H2
  2. 5% H2 + 9% N2
  3. 100% CO
  4. 100% H2

Correct answer: (A)
95% N2 + 5% H2

77.Pulverised fuel fired furnaces employ _________ fuel firing.

  1. Horizontal
  2. Vertical
  3. Tangential
  4. All (A), (B) and (C)

Correct answer: (D)
All (A), (B) and (C)

78.Rate of heat release in a furnace, which is the measure of heat intensity, is defined as

  1. kcal/hr/m3 combustion space
  2. kcal/m3 combustion space
  3. kcal/hr
  4. None of these

Correct answer: (A)
kcal/hr/m3 combustion space

79.Reducing atmosphere is maintained in a

  1. Calcination kiln
  2. Blast furnace
  3. Soaking pit
  4. L.D. converter

Correct answer: (B)
Blast furnace

80.Regenerators are installed in

  1. Coke ovens
  2. Open hearth furnace
  3. Both (A) & (B)
  4. Neither (A) nor (B)

Correct answer: (C)
Both (A) & (B)

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