Q.1

Circulation of gases in furnace is caused by the

  • change in volume during a change of temperature.
  • difference in density between hot and cold gases.
  • furnace pressure in conjunction with draft in flues.
  • all (a), (b) and (c).
Q.2

Fuel economy in furnaces can be achieved by

  • using oxygen enriched combustion air.
  • preheating the combustion air.
  • reducing the heat loss through furnace openings & doors.
  • all (a), (b) and (c).
Q.3

Which of the following advantages is not associated with the use of preheated air for combustion of a fuel in the furnace ?

  • Increase in calorific value of the fuel.
  • Increase in flame temperature.
  • Reduction in scale losses.
  • Saving in fuel consumption.
Q.4

Unit of furnace loading is

  • ton stock/hr/m2 hearth area
  • ton stock/hr
  • ton stock/m2 hearth area
  • both (b) and (c)
Q.5

In order to maintain an oxidising atmosphere in a furnace, it should have

  • more of excess air
  • less of excess air
  • more of CO in flue gas
  • more of CO2 in flue gas
Q.6

Advantages of use of preheated combustion air are

  • saving in fuel consumption.
  • reduction in scale losses.
  • increase in flame temperature.
  • all (a), (b) and (c).
Q.7

Oxygen enrichment of combustion air does not result in increase of the

  • flame temperature.
  • oxygen in the flue gas.
  • stack loss.
  • heat transfer rate in the furnace.
Q.8

The rate of scaling of furnace stock depends upon the

  • temperature
  • time
  • nature of atmosphere
  • all (a), (b) and (c)
Q.9

Overfire burning in a furnace is a phenomenon characterised by

  • supply of excess fuel.
  • supply of excess air.
  • burning carbon monoxide and other incombustible in upper zone of furnace by supplying more air.
  • none of these.
Q.10

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.

  • 5
  • 60
  • 20
  • 40
Q.11

Furnace aerodynamics is related to the __________ in the furnace.

  • movement of gases
  • measurement of flue gas volume
  • temperature control
  • pressure adjustment
Q.12

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

  • 5
  • 20
  • 50
  • 80
Q.13

A refractory wall separating the stock and the source of heat is provided in a

  • updraft kiln
  • muffle furnace
  • continuous furnace
  • none of these
Q.14

In a furnace operation, which is not preheated ?

  • Solid fuels.
  • Hydrocarbon containing fuel gases (e.g. coke oven gas, refinery gas etc.).
  • Both (a) and (b).
  • Neither (a) nor (b).
Q.15

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

  • flue gas volume
  • flame temperature
  • fuel consumption
  • stack loss
Q.16

Amount of coal lost in ash particle, which is carried through the boiler system, depends upon the

  • physical nature, ash content and fineness of the coal.
  • amount of excess air supplied and load on the boiler.
  • type of burner and combustion chamber.
  • all (a), (b) and (c)
Q.17

An example of recuperative furnace is the

  • soaking pit
  • open hearth furnace
  • coke ovens
  • none of these
Q.18

Main gas valve in a gaseous fuel burner is a __________ valve.

  • gate
  • butterfly
  • globe
  • none of these
Q.19

If fuel and air are mixed ahead of the burner, it is called a/an __________ burner.

  • premix
  • outside mixing type
  • rotary
  • diffusion
Q.20

The advantages of firing pulverised coal in the furnace lies in the fact that, it

  • permits the use of high ash content coal.
  • permits the use of low fusion point ash coal.
  • accelerates the burning rate and economises on fuel consumption.
  • all (a), (b) and (c).
Q.21

If the flame is produced under the hearth and then sweeps up into the heating chamber, this is called a/an __________ furnace.

  • sidefired
  • underfired
  • covered
  • recirculating
Q.22

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

  • < 2
  • < 5
  • < 8
  • < 10
Q.23

Which one shows the diagramatic heat balance in a furnace ?

  • Sankey diagram
  • Cox chart
  • Ostwald chart
  • None of these
Q.24

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

  • regenerative
  • recuperative
  • both (a) and (b)
  • neither (a) nor (b).
Q.25

Reducing atmosphere is maintained in a

  • calcination kiln
  • blast furnace
  • soaking pit
  • L.D. converter
Q.26

In case of pulverised coal fired steam boiler, the secondary air serves the main purpose of

  • transportation of coal.
  • drying of coal.
  • combustion of coal by supplying it around the burner.
  • preheating the primary air.
Q.27

Neutral atmosphere is maintained in a/an __________ furnace.

  • cold rolled steel coil annealing
  • open hearth
  • soaking pit
  • walking beam reheating
Q.28

Which of the following is a rotary furnace?

  • Lime kiln
  • Soaking pit
  • Stoves
  • Annealing furnace.
Q.29

Decarburisation of steel

  • is the removal of carbon from iron carbide (Fe3C).
  • affects its crystalline structure.
  • is favoured by CO2.
  • all (a), (b) and (c).
Q.30

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

  • accelerating the rate of scaling.
  • causing metal embrittlement.
  • attacking the grain boundaries; particularly severe on low carbon and nickel bearing steels at high temperature.
  • all (a), (b) and (c).
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