Practice Furnace Technology Multiple Choice Questions with Answers Quiz-7

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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