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Furnace Technology MCQ Questions & Answers

Furnace Technology MCQs : This section focuses on the "Furnace Technology". These Multiple Choice Questions (MCQs) should be practiced to improve the Furnace Technology skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.




Question 1

__________ atmosphere is maintained inside an iron blast furnace.

A. Oxidising
B. Reducing
C. Inert
D. Decarburising

View Answer

Question 2

__________ is an indirectly heated furnace.

A. Open hearth furnace
B. Muffle furnace
C. Soaking pit
D. Reheating furnace

View Answer

Question 3

Acid dew point temperature (ADT) of a flue gas produced by the combustion of a fuel containing 1% sulphur may be about __________ °C.

A. 80
B. 130
C. 180
D. 250

View Answer

Question 4

An example of a periodic furnace is the

A. blast furnace stoves
B. blast furnace
C. coke oven heating chamber
D. rotary kilns

View Answer

Question 5

An example of shaft furnace is the

A. L.D. converter
B. glass melting tank
C. blast furnace
D. soaking pit

View Answer

Question 6

Calcination of limestone to produce lime is done in a __________ kiln.

A. tunnel
B. rotary
C. vertical shaft
D. both (b) and (c)

View Answer

Question 7

Cement Kiln is a

A. rotary Kiln
B. tunnel Kiln
C. natural draft furnace
D. batch furnace

View Answer

Question 8

Ceramic coating material for furnace refractory, which increases its emissivity and thus the radiation heat transfer rate in the furnace, comprises of

A. graphite powder
B. thoria
C. zircon powder
D. beryllium

View Answer

Question 9

Ceramic recuperators (made of SiC) is economical, only when used for preheating combustion air above __________ °C.

A. 250
B. 650
C. 850
D. 1000

View Answer

Question 10

Ceramic recuperators compared to metallic recuperators for the same duty

A. are lighter.
B. occupy more space.
C. are less costly.
D. have higher pressure differential between flue gas & air side.

View Answer

Question 11

Coke ovens in steel plant are heated by

A. electricity
B. blast furnace gas/mixed gas
C. coke oven gas
D. both (b) and (c)

View Answer

Question 12

Example of an indirectly heated furnace is

A. hood annealing furnace
B. muffle furnace
C. both (a) and (b)
D. neither (a) nor (b)

View Answer

Question 13

Fuel used in B.F. stove is

A. pulverised coal
B. furnace oil
C. blast furnace gas/mixed gas
D. coke oven gas

View Answer

Question 14

Heat transfer rate to the stock/charge in the furnace does not depend upon the

A. emissivity of the refactory walls.
B. size of the furance.
C. use of waste heat recovery equipments.
D. thickness of the stock.

View Answer

Question 15

Higher furnace temperature can not be achieved by use of a lean fuel gas in the furnace by

A. increasing the draft in the furnace.
B. preheating the fuel gas.
C. oxygen enrichment of combustion air.
D. preheating the combustion air.

View Answer

Question 16

In a furnace employing forced draught as compared to induced draught,

A. air is sucked in, so air leaks are more and hence the furnace efficiency is reduced.
B. the fan operates hot and hence blades are liable to corrosion and erosion.
C. positive pressure exists in the furnace.
D. none of these

View Answer

Question 17

In a muffle furnace, the muffle

A. retards the heat transfer.
B. assists in temperature equalisation in the charge.
C. permits the use of controlled atmosphere for the protection of stock.
D. all (a), (b) and (c).

View Answer

Question 18

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

A. no O2 in flue gas
B. CO in flue gas
C. high excess air
D. none of these

View Answer

Question 19

In producer gas making furnace, steam is added along with air to mainly control the

A. fusion of coal ash & clinker formation.
B. C. V. of producer gas.
C. temperature of producer gas.
D. tar content in producer gas.

View Answer

Question 20

In reverberatory furnace, charge is heated mainly by

A. conduction.
B. natural convection.
C. radiation of heat from the roof of the combustion chamber.
D. none of these.

View Answer

Question 21

Large tonnage of refractory bricks are dried in a

A. shaft furnace
B. rotary hearth furnace
C. tunnel kiln
D. muffle furnace

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Question 22

Low stack loss indicates the

A. use of sub-stoichiometric air for combustion.
B. efficient use of fuel.
C. inefficient use of fuel.
D. oxygen enrichment of combustion air.

View Answer

Question 23

Maximum heat transfer in high temperature furnaces is by

A. conduction
B. convection
C. radiation
D. either (a), (b) or (c); depends on the type of furnace

View Answer

Question 24

Means for giving direction to the circulation of gases in furnaces are

A. fans.
B. arrangement of heating stock in the furnaces.
C. location of outlet ports and heating & combustion devices.
D. all (a), (b) and (c).

View Answer

Question 25

Ostwald charts are meant for

A. computing the excess/deficiency of combustion air.
B. calculation of flue gas temperature.
C. computation of flue gas analysis.
D. none of these.

View Answer

Question 26

Pulverised fuel fired furnaces employ __________ fuel firing.

A. horizontal
B. vertical
C. tangential
D. all (a), (b) and (c)

View Answer

Question 27

Regenerators are installed in

A. coke ovens
B. open hearth furnace
C. both (a) & (b)
D. neither (a) nor (b)

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Question 28

Soaking pits are meant for heating steel

A. ingots
B. coils
C. sheets
D. slabs

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Question 29

Temperature of a furnace fired with low calorific value fuel gas (i.e. lean gas) can be increased by

A. preheating the combustion air.
B. oxygen enrichment of combustion air.
C. preheating the fuel gas.
D. all (a), (b) & (c).

View Answer

Question 30

The amount of combustible escaping uncon-sumed from the furnace, depends upon the

A. air supplied and furnace temperature.
B. burner design (thoroughness of mixing versus stratification).
C. air preheat and the flow of gases in the furnace (mixing by induction, by acceleration or by change of direction).
D. all (a), (b) and (c).

View Answer

Question 31

The heat recoverable from flue gases of furnaces depends on the

A. thermal efficiency of furnace.
B. quantity of flue gases.
C. flue gas temperature drop through the furnace.
D. all (a), (b) and (c).

View Answer

Question 32

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

A. oxidation/scaling
B. decarburising
C. sulphur penetration
D. either of the above

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Question 33

The reason for excessive clinker formation in gas producers is the

A. use of coal/coke containing a high % of fines and ash.
B. use of fuel having too low an ash fusion temperature.
C. development of hot spots in the fuel bed and an abnormally high rate of gasification.
D. all (a), (b) and (c).

View Answer

Question 34

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

A. 15
B. 40
C. 70
D. 85

View Answer

Question 35

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

A. 50
B. 65
C. 85
D. 99

View Answer

Question 36

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

A. 20
B. 40
C. 65
D. 80

View Answer

Question 37

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

A. 20
B. 40
C. 60
D. 80

View Answer

Question 38

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

A. low emissivity
B. high thermal conductivity
C. both (a) and (b)
D. neither (a) nor (b)

View Answer

Question 39

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

A. preheating of cold stock.
B. preheating of combustion air.
C. steam generation in waste heat boilers.
D. all (a), (b) and (c).

View Answer

Question 40

Tunnel kilns are usually used for

A. roasting of pyrites.
B. drying/tempering of refractories.
C. reheating of slabs.
D. melting of glass.

View Answer

Question 41

Which furnace employs preheating, heating and soaking zones ?

A. Soaking pit
B. Reheating furnace
C. Open hearth furnace
D. Cupola

View Answer

Question 42

Which is a continuous furnace ?

A. Coke ovens
B. Annealing furnace
C. Glass tank furnace
D. None of these

View Answer

Question 43

Which is not a hearth furnace ?

A. Glass tank furnace
B. Open hearth furnace
C. Cupola
D. Reheating furnace

View Answer

Question 44

Which is the most thermally efficient furnace ?

A. Reheating furnace
B. Reverberatory furnace
C. Rotary kilns
D. Boiler furnace

View Answer

Question 45

Which of the following is a heat treatment furnace ?

A. Muffle furnace
B. Annealing furnace
C. Reheating furnace
D. Rotary kiln

View Answer

Question 46

Which of the following is a natural draft furnace ?

A. Blast furnace stoves
B. Power plant boilers
C. Sintering furnace
D. None of these

View Answer

Question 47

Which of the following is not a directly fired furnace ?

A. By-product coke oven
B. Calcination kiln
C. Sintering furnace
D. Open hearth furnace

View Answer

Question 48

Which of the following is not an additive for flue gases from furnace to reduce its dew-point?

A. Ammonia
B. Fine dolomite
C. Alkaline powders
D. None of these

View Answer

Question 49

Which of the following is the most suitable for preheating combustion air above 650°C ?

A. Regenerator
B. Metallic recuperator
C. Ceramic recuperator
D. None of these

View Answer

Question 50

Overfire burning in a furnace is a phenomenon characterised by

A. Supply of excess fuel
B. Supply of excess air
C. Burning carbon monoxide and other incombustible in upper zone of furnace by supplying more air
D. None of these

View Answer

Question 51

Which of the following variables does not affect the furnace capacity?

A. Size of the furnace
B. Gas velocity in furnace
C. Ratio of wall surface to surface of stock
D. None of these

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Question 52

Reducing atmosphere is maintained in a

A. Calcination kiln
B. Blast furnace
C. Soaking pit
D. L.D. converter

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Question 53

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

A. Gate
B. Butterfly
C. Globe
D. None of these

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Question 54

Ingress of cold air in the furnaces through cracks, charging doors, openings etc.

A. Reduces the flue gas temperature and makes the furnace atmosphere oxidising
B. Increases the load on the induced draft fan
C. Reduces the furnace draught
D. All of the above

View Answer

Question 55

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

A. Coke oven
B. Blast furnace stoves
C. Beehive coke oven
D. High pressure boiler

View Answer

Question 56

The function of an economiser in a boiler is to preheat the

A. Feedwater
B. Combustion air
C. Pulverised coal
D. Furnace oil

View Answer

Question 57

Which of the following is a heat treatment furnace?

A. Muffle furnace
B. Annealing furnace
C. Reheating furnace
D. Rotary kiln

View Answer

Question 58

The electric furnace in which heat is produced by a combination of induced current and skin effect is called __________ furnace.

A. Arc
B. Resistance
C. Low frequency induction
D. High frequency induction

View Answer

Question 59

An electric furnace producing heat by means of an electric arc struck between each of three electrodes and the charge is called __________ furnace.

A. Resistance
B. Arc
C. Low frequency induction
D. None of these

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Question 60

Calcination of limestone to produce lime is done in a __________ kiln.

A. Tunnel
B. Rotary
C. Vertical shaft
D. Both B and C

View Answer

Question 61

Pot furnace which is either regenerative or recupterative, is used in the manufacture of

A. Glass
B. Stainless steel
C. Potteries
D. Refractory bricks

View Answer

Question 62

Temperature of a furnace fired with low calorific value fuel gas (i.e. lean gas) can be increased by

A. Preheating the combustion air
B. Oxygen enrichment of combustion air
C. Preheating the fuel gas
D. All of the above

View Answer

Question 63

The heating capacity of muffle furnace depends on the

A. Surface area & emissivity of the stock
B. Properties of the muffle wall (temperature, area, emissivity)
C. Both A & B
D. Neither A nor B

View Answer

Question 64

Fuel economy in an industrial furnace operation can not be achieved by the use of

A. Stoichiometric combustion air
B. Non-preheated combustion air
C. Combustion air not enriched with oxygen
D. Recupterators

View Answer

Question 65

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

A. Flame temperature
B. Oxygen in the flue gas
C. Stack loss
D. Heat transfer rate in the furnace

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Question 66

Size of the combustion chamber of a furnace depends upon the

A. Heat release rate of the fuel
B. Preheat temperature of fuel & air
C. Method of mixing the fuel & air
D. All of the above

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Question 67

Forced recirculation of furnace gases is practised

A. To increase heat transfer by convection
B. To ensure uniform temperature
C. In furnaces, operating below 750°C
D. All of the above

View Answer

Question 68

The amount of combustible escaping uncon-sumed from the furnace, depends upon the

A. Air supplied and furnace temperature
B. Burner design (thoroughness of mixing versus stratification)
C. Air preheat and the flow of gases in the furnace (mixing by induction, by acceleration or by change of direction)
D. All of the above

View Answer

Question 69

Which is the most thermally efficient furnace?

A. Reheating furnace
B. Reverberatory furnace
C. Rotary kilns
D. Boiler furnace

View Answer

Question 70

In a heating process, a heat flow diagram in which the quantities of heat in the various items of a heat balance are represented by the width of a band is called the

A. Ostwald chart
B. Cox chart
C. Sankey diagram
D. None of these

View Answer

Question 71

An improved and fuel efficient version of the pusher type reheating furnace is the __________ furnace.

A. Walking beam
B. Shaft
C. Tunnel
D. Rotary hearth

View Answer

Question 72

Which of the following variables affects the furnace capacity?

A. Temperature of flue gas
B. Thermal conductivity of stock
C. Thickness of heating stock
D. All of the above

View Answer

Question 73

Air filtration in a furnace

A. Reduces its thermal efficiency
B. Is indicated by flame sting out
C. Increases the flue gas temperature
D. None of these

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Question 74

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

A. Transportation of coal
B. Drying of coal
C. Combustion of coal by supplying it around the burner
D. Preheating the primary air

View Answer

Question 75

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

A. Sidefired
B. Underfired
C. Covered
D. Recirculating

View Answer

Question 76

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

A. < 2
B. < 5
C. < 8
D. < 10

View Answer

Question 77

Hearth furnaces are not used for

A. Roasting
B. Melting
C. Reheating
D. None of these

View Answer

Question 78

The heating capacity of continuous reheating furnace depends upon the

A. Hearth area and furnace temperature
B. Emissivity of the stock
C. Ratio of wall surface to stock surface
D. All of the above

View Answer

Question 79

Means for giving direction to the circulation of gases in furnaces are

A. Fans
B. Arrangement of heating stock in the furnaces
C. Location of outlet ports and heating & combustion devices
D. All of the above

View Answer

Question 80

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

A. Premix
B. Outside mixing type
C. Rotary
D. Diffusion

View Answer

Question 81

Out of the following fuels used in a furnace exhausting flue gas at a temperature of 600°C, the percentage stack loss will be maximum in case of complete combustion of

A. Furnace oil with air
B. Furnace oil with oxygen
C. Blast furnace gas with air
D. Blast furnace gas with oxygen

View Answer

Question 82

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

A. 95% N₂ + 5% H₂
B. 5% H₂ + 9% N₂
C. 100% CO
D. 100 %H₂

View Answer

Question 83

__________ furnace is not an electric furnace.

A. Arc
B. Induction
C. Pot
D. Resistance

View Answer

Question 84

In reverberatory furnace, charge is heated mainly by

A. Conduction
B. Natural convection
C. Radiation of heat from the roof of the combustion chamber
D. None of these

View Answer

Question 85

Scaling of furnace stock is reduced by __________ in flue gas.

A. CO
B. H₂
C. High CO/CO₂
D. All of the above

View Answer

Question 86

Which is a regenerative furnace?

A. Coke oven heating chamber
B. Open hearth furnace
C. Both A and B
D. Neither A nor B

View Answer

Question 87

Dampers are located

A. Before the I.D fan
B. After the I.D. fan
C. Near the top of the chimney
D. Anywhere after the I.D. fan

View Answer

Question 88

Decarburisation of steel

A. Is the removal of carbon from iron carbide (Fe₃C)
B. Affects its crystalline structure
C. Is favoured by CO₂
D. All of the above

View Answer

Question 89

An example of indirectly heated furnace is the

A. Soaking pit
B. Muffle furnace
C. Reheating furnace
D. None of these

View Answer

Question 90

The resistance furnace produces heat by the

A. Electric arc struck between electrodes and the charge
B. Flow of current through a heating element
C. Combination of induced current and skin effect
D. None of these

View Answer

Question 91

Which of the following is not a continuous waste heat recovery equipment from the flue gases going out of furnace?

A. Economiser
B. Regenerator
C. Ceramic recuperator
D. Waste heat boiler

View Answer

Question 92

Flue gas outlet temperature from the chimney of any furnace should be ideally about __________ °C.

A. 50
B. 100
C. 150
D. 250

View Answer

Question 93

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

A. No O₂ in flue gas
B. CO in flue gas
C. High excess air
D. None of these

View Answer

Question 94

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

A. More of excess air
B. Less of excess air
C. More of CO in flue gas
D. More of CO₂ in flue gas

View Answer

Question 95

Which of the following furnaces will have maximum thermal efficiency?

A. Soaking pits
B. Walking beam reheating furnace
C. Boiler furnace
D. Rotary kilns

View Answer

Question 96

Blast furnace stoves are meant for heating

A. Air
B. Blast furnace gas
C. Steam
D. None of these

View Answer

Question 97

Higher furnace temperature can not be achieved by use of a lean fuel gas in the furnace by

A. Increasing the draft in the furnace
B. Preheating the fuel gas
C. Oxygen enrichment of combustion air
D. Preheating the combustion air

View Answer

Question 98

Neutral atmosphere is maintained in a/an __________ furnace.

A. Cold rolled steel coil annealing
B. Open hearth
C. Soaking pit
D. Walking beam reheating

View Answer

Question 99

The method of Lobo and Evans is concerned with the calculation of the

A. Heat absorption in radiant section of a furnace
B. Heat transfer by forced convection in a reboiler
C. Heat transfer in vacuum condensers
D. Mass transfer co-efficient

View Answer

Question 100

Pulverised fuel fired furnaces employ __________ fuel firing.

A. Horizontal
B. Vertical
C. Tangential
D. All of the above

View Answer

Question 101

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

A. Flue gas volume
B. Flame temperature
C. Fuel consumption
D. Stack loss

View Answer

Question 102

Reverberatory furnace is used for

A. Roasting/reduction of ores
B. Annealing steel coil
C. Heating air
D. Steel melting

View Answer

Question 103

Which of the following is the most important deterrants to an extended use of pulverised coal in boiler firing?

A. Ash disposal problem
B. Excessive fly ash discharge from the stack
C. Higher power consumption in its transportation
D. Erosion of induced draft fan blades

View Answer

Question 104

Circulation of gases in furnace is caused by the

A. Change in volume during a change of temperature
B. Difference in density between hot and cold gases
C. Furnace pressure in conjunction with draft in flues
D. All of the above

View Answer

Question 105

Metallic recuperators are not used for waste heat recovery, if the hot flue gas temperature is above __________ °C, because corrosion prevails at higher temperatures.

A. 350
B. 750
C. 1050
D. 1250

View Answer

Question 106

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

A. Kcal/hr/m³ combustion space
B. Kcal/m³ combustion space
C. Kcal/hr
D. None of these

View Answer

Question 107

Advantages of use of preheated combustion air are

A. Saving in fuel consumption
B. Reduction in scale losses
C. Increase in flame temperature
D. All of the above

View Answer

Question 108

In salt bath furnace, heat is transferred to the charge mainly by

A. Conduction
B. Convection
C. Radiation
D. None of these

View Answer

Question 109

Which of the following is a batch furnace?

A. Cupola
B. Reheating furnace
C. Glass tank furnace
D. None of these

View Answer

Question 110

Which of the following is a rotary furnace?

A. Lime kiln
B. Soaking pit
C. Stoves
D. Annealing furnace

View Answer

Question 111

Which furnace employs natural draft?

A. Coke oven
B. Boiler
C. Rotary kilns
D. L.D. converter

View Answer

Question 112

Heat balance of furnace provides means of determining the

A. Thermal efficiency of the process
B. Sources of heat losses
C. Scope of reduction of heat losses
D. All of the above

View Answer

Question 113

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

A. Economiser
B. Steam superheater
C. Air preheater
D. All of the above

View Answer

Question 114

In producer gas making furnace, steam is added along with air to mainly control the

A. Fusion of coal ash & clinker formation
B. C. V. of producer gas
C. Temperature of producer gas
D. Tar content in producer gas

View Answer

Question 115

Maximum thermal efficiency of boiler may be about __________ percent.

A. 10
B. 25
C. 65
D. 90

View Answer

Question 116

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

A. 10-15
B. 25-30
C. 45-50
D. 65-70

View Answer

Question 117

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

A. 5
B. 20
C. 50
D. 80

View Answer

Question 118

Furnace pressure is normally controlled by regulating the

A. Air pressure
B. Fuel gas pressure
C. Speed of I.D. fan
D. Damper

View Answer

Question 119

Which of the following is a directly fired intermittant furnace?

A. Walking beam reheating furnace
B. Reverberatory furnace
C. Tower furnace
D. Tunnel kiln

View Answer

Question 120

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

A. Preheating of cold stock
B. Preheating of combustion air
C. Steam generation in waste heat boilers
D. All of the above

View Answer

Question 121

Specific heating capacity of a furnace is expressed as

A. Weight heated/hr
B. Weight heated/furnace volume
C. Weight heated/hr/furnace volume
D. None of these

View Answer

Question 122

Design of waste heat boiler for recovery of waste heat from furnace gases depends upon the

A. Quantity & temperature of waste gas
B. Dust concentration & nature of dust in waste gas
C. Corrosive nature of the waste gas
D. All of the above

View Answer

Question 123

The rate of scaling of furnace stock depends upon the

A. Temperature
B. Time
C. Nature of atmosphere
D. All of the above

View Answer

Question 124

Which of the following is a natural draft furnace?

A. Blast furnace stoves
B. Power plant boilers
C. Sintering furnace
D. None of these

View Answer

Question 125

Which furnace employs preheating, heating and soaking zones?

A. Soaking pit
B. Reheating furnace
C. Open hearth furnace
D. Cupola

View Answer

Question 126

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

A. Low emissivity
B. High thermal conductivity
C. Both A and B
D. Neither A nor B

View Answer

Question 127

Which is not accomplished in an underfired furnace?

A. Increase in heating capacity/m² of floor space
B. Elimination of cold spot at the bottom of the charge
C. Reduction in the temperature of furnace gases
D. Portection of the periphery of the charge from excessive radiation

View Answer

Question 128

Which is a continuous furnace?

A. Coke ovens
B. Annealing furnace
C. Glass tank furnace
D. None of these

View Answer

Question 129

Which is not a hearth furnace?

A. Glass tank furnace
B. Open hearth furnace
C. Cupola
D. Reheating furnace

View Answer

Question 130

Which one shows the diagramatic heat balance in a furnace?

A. Sankey diagram
B. Cox chart
C. Ostwald chart
D. None of these

View Answer

Question 131

Maximum heat transfer in high temperature furnaces is by

A. Conduction
B. Convection
C. Radiation
D. Either A, B or C; depends on the type of furnace

View Answer

Question 132

Fuel economy in furnaces can be achieved by

A. Using oxygen enriched combustion air
B. Preheating the combustion air
C. Reducing the heat loss through furnace openings & doors
D. All of the above

View Answer

Question 133

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

A. Increase in calorific value of the fuel
B. Increase in flame temperature
C. Reduction in scale losses
D. Saving in fuel consumption

View Answer

Question 134

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

A. Regenerative
B. Recuperative
C. Both A and B
D. Neither A nor B

View Answer

Question 135

In practical operation of any furnace, zero oxygen percentage or theoretical CO₂ percentage in flue gas is rarely achieved, because of

A. Use of non-preheated combustion air
B. Use of pulverised solid fuels
C. Imperfect mixing of fuel & air and infiltration of air
D. Use of excessive positive draft in the furnace

View Answer

Question 136

The main function of a muffle in the muffle furnace is to

A. Protect the charge from the effects of the products of combustion
B. Smooth out temperature inequalities on the combustion side of the muffle wall
C. Both A & B
D. Neither A nor B

View Answer

Question 137

Which of the following is a periodic furnace?

A. Tunnel kiln
B. Rotary kiln
C. Soaking pit
D. Reheating furnace

View Answer

Question 138

Low stack loss indicates the

A. Use of sub-stoichiometric air for combustion
B. Efficient use of fuel
C. Inefficient use of fuel
D. Oxygen enrichment of combustion air

View Answer

Question 139

In furnaces operating at very high temperature (say) 1250°C, e.g. soaking pit), the maximum heat transfer takes place by

A. Conduction
B. Convection
C. Radiation
D. Can not be predicted

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Question 140

The reason for excessive clinker formation in gas producers is the

A. Use of coal/coke containing a high % of fines and ash
B. Use of fuel having too low an ash fusion temperature
C. Development of hot spots in the fuel bed and an abnormally high rate of gasification
D. All of the above

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Question 141

In a muffle furnace, the muffle

A. Retards the heat transfer
B. Assists in temperature equalisation in the charge
C. Permits the use of controlled atmosphere for the protection of stock
D. All of the above

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Question 142

Example of an indirectly heated furnace is

A. Hood annealing furnace
B. Muffle furnace
C. Both A and B
D. Neither A nor B

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Question 143

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

A. Permits the use of high ash content coal
B. Permits the use of low fusion point ash coal
C. Accelerates the burning rate and economises on fuel consumption
D. All of the above

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Question 144

Tunnel kilns are usually used for

A. Roasting of pyrites
B. Drying/tempering of refractories
C. Reheating of slabs
D. Melting of glass

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Question 145

Which of the following is not a directly fired furnace?

A. By-product coke oven
B. Calcination kiln
C. Sintering furnace
D. Open hearth furnace

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Question 146

Test specimen for determination of refractoriness under load (RUL) of a refractory is heated in a

A. Furnace employing neutral atmosphere
B. Carbon resistance furnace
C. Reducing atmosphere
D. Furnace employing negative pressure

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Question 147

Thermal efficiency of furnaces can be improved by

A. Waste heat recovery from flue gas
B. Minimising heat losses from furnace walls
C. Maintaining proper draught
D. All of the above

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Question 148

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

A. Physical nature, ash content and fineness of the coal
B. Amount of excess air supplied and load on the boiler
C. Type of burner and combustion chamber
D. All of the above

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Question 149

Which of the following accentuates clinker-ing troubles on furnace grate burning coal?

A. Low reactivity of carbonised residue containing high proportion of iron & sulphur
B. Low forced draft & fuel bed temperature
C. Thick firebed and preheated primary air
D. All of the above

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Question 150

Ostwald charts are meant for

A. Computing the excess/deficiency of combustion air
B. Calculation of flue gas temperature
C. Computation of flue gas analysis
D. None of these

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Question 151

Which one is not an induced draught furnace?

A. Blast furnace stove
B. Sintering furnace
C. High pressure boiler
D. None of these

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Question 152

In which of the following furnaces, the gases are sucked through the stock bed from below?

A. Soaking pit
B. Sintering machine
C. Beehive oven
D. None of these

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Question 153

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

A. Updraft kiln
B. Muffle furnace
C. Continuous furnace
D. None of these

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Question 154

Pick out the wrong statement.

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

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Question 155

While the fuel fired furnace can be used upto a maximum temperature of about 1700°C, the electric furnace can be used upto a temperature of about __________ °C.

A. 2000
B. 3000
C. 4500
D. 6000

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Question 156

In a furnace, the heat taken by the charge/stock and the heat lost to the furnace structure & flue gases depends on the

A. Rate of firing and emissivity of flame
B. Thermal conductivity of the charge & structural materials of furnace
C. Nature of process ; whether batch, continuous or intermittant
D. All of the above

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Question 157

Very high pressure boilers are usually __________ boilers.

A. Fire tube
B. Water tube
C. Waste heat
D. Natural circulation

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Question 158

Recuperator is

A. Not used for fuel gas preheating
B. An intermittant waste heat recovery equipment
C. A continuous waste heat recovery equipment
D. Heavier than regenerator meant for the same duty

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Question 159

Ceramic recuperators compared to metallic recuperators for the same duty

A. Are lighter
B. Occupy more space
C. Are less costly
D. Have higher pressure differential between flue gas & air side

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Question 160

Regenerators compared to the recuperators for the same duty

A. Occupy more space
B. Are less costly
C. Are of smaller size
D. All of the above

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Question 161

Regenerators as compared to recuperators for the same duty

A. Store smaller quantity of waste heat
B. Are lighter & compact
C. Involve higher initial cost
D. All of the above

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Question 162

Regenerators are installed in

A. Coke ovens
B. Open hearth furnace
C. Both A & B
D. Neither A nor B

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Question 163

Use of pulverised coal in boilers provides

A. Higher calorific value
B. Better combustion
C. Smokeless burning
D. Less erosion on furnace wall

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Question 164

Artificial draught produced by a fan in the furnace can be controlled by the

A. Speed of the fan
B. Damper
C. Variation in the pitch of fan blades
D. All of the above

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Question 165

Heat transfer rate to the stock/charge in the furnace does not depend upon the

A. Emissivity of the refactory walls
B. Size of the furance
C. Use of waste heat recovery equipments
D. Thickness of the stock

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Question 166

Heat transfer rate to the charge/stock in a furnace does not depend upon the

A. Type of fuels viz solid, liquid or gaseous
B. Flue gas temperature
C. Emissivity of refractory walls
D. Initial temperature of the charged stock

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Question 167

In low or standard frequency induction furnace, heat is produced by the

A. Combination of induced current and skin effect
B. Induction and resistance
C. Current flow through a heating element
D. None of these

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Question 168

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.

A. 5
B. 60
C. 20
D. 40

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Question 169

Rotary kilns are used in the

A. Calcination of limestone & dolomite
B. Cement manufacture
C. Both A and B
D. Neither A nor B

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Question 170

Regenerators are normally provided in the

A. Glass melting furnace
B. Open hearth furnace
C. By product coke ovens
D. All of the above

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Question 171

In a furnace employing forced draught as compared to induced draught,

A. Air is sucked in, so air leaks are more and hence the furnace efficiency is reduced
B. The fan operates hot and hence blades are liable to corrosion and erosion
C. Positive pressure exists in the furnace
D. None of these

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Question 172

Coke ovens in steel plant are heated by

A. Electricity
B. Blast furnace gas/mixed gas
C. Coke oven gas
D. Both B and C

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Question 173

Which of the following is not a recuperative furnace?

A. Soaking pit
B. Reheating furnace
C. Steamboiler
D. Coke oven

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Question 174

Regenerators are used for waste heat recovery in

A. By-product coke ovens
B. Beehive coke oven
C. Blast furnace stoves
D. Soaking pits

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Question 175

The heat recoverable from flue gases of furnaces depends on the

A. Thermal efficiency of furnace
B. Quantity of flue gases
C. Flue gas temperature drop through the furnace
D. All of the above

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Question 176

Shaft furnaces are used for

A. Smelting
B. Calcining
C. Roasting
D. All of the above

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Question 177

Reheating furnace (pusher type) is used for heating

A. Ingots
B. Slabs
C. Steel coils
D. Steel sheets

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Question 178

In which of the waste heat recovery equipment, the flow of flue gas and air is alternately reversed after a fixed interval of time?

A. Recuperator
B. Regenerator
C. Waste heat boiler
D. None of these

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Question 179

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

A. Range of fuel firing rates
B. Volume of the combustion chamber
C. Maximum heat input rate only
D. Minimum heat input rate only

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Question 180

Furnace aerodynamics is related to the __________ in the furnace.

A. Movement of gases
B. Measurement of flue gas volume
C. Temperature control
D. Pressure adjustment

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Question 181

In a furnace operation, which is not preheated?

A. Solid fuels
B. Hydrocarbon containing fuel gases (e.g. coke oven gas, refinery gas etc.)
C. Both A and B
D. Neither A nor B

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Question 182

Turn down ratio of a burner

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

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Question 183

Heat transfer takes place through a liquid medium surrounding the submerged material under heating, in case of a/an

A. Blast furnace
B. Steam boiler
C. Salt bath furnace
D. Annealing furnace

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Question 184

Unit of furnace loading is

A. Ton stock/hr/m² hearth area
B. Ton stock/hr
C. Ton stock/m² hearth area
D. Both B and C

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