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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

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

View Answer

Question 2

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 3

Which is the most thermally efficient furnace ?

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

View Answer

Question 4

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 5

Which one is not an induced draught furnace?

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

View Answer

Question 6

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

View Answer

Question 7

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 8

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 9

Which of the following is a rotary furnace?

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

View Answer

Question 10

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

View Answer

Question 11

Which is a continuous furnace ?

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

View Answer

Question 12

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 13

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 14

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 15

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

View Answer

Question 16

Reheating furnace (pusher type) is used for heating

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

View Answer

Question 17

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

View Answer

Question 18

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 19

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 20

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 21

Which is a continuous furnace?

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

View Answer

Question 22

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 23

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 24

Which is not a hearth furnace?

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

View Answer

Question 25

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

View Answer

Question 26

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 27

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 28

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 29

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 30

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 31

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

View Answer

Question 32

An example of shaft furnace is the

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

View Answer

Question 33

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 34

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

View Answer

Question 35

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 36

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 37

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 38

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 39

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 40

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

View Answer

Question 41

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 42

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 43

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 44

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 45

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 46

Which of the following is a periodic furnace?

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

View Answer

Question 47

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

View Answer

Question 48

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 49

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 50

Which is not a hearth furnace ?

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

View Answer

Question 51

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 52

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

View Answer

Question 53

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 54

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

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

View Answer

Question 55

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

View Answer

Question 56

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

View Answer

Question 57

Which is the most thermally efficient furnace?

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

View Answer

Question 58

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

View Answer

Question 59

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 60

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 61

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 62

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 63

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 64

Which of the following is a heat treatment furnace ?

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

View Answer

Question 65

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 66

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

View Answer

Question 67

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

View Answer

Question 68

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 69

Hearth furnaces are not used for

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

View Answer

Question 70

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

View Answer

Question 71

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 72

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

View Answer

Question 73

Which of the following is not a recuperative furnace?

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

View Answer

Question 74

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 75

Regenerators are normally provided in the

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

View Answer

Question 76

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 77

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 78

Pulverised fuel fired furnaces employ __________ fuel firing.

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

View Answer

Question 79

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 80

Regenerators are installed in

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

View Answer

Question 81

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

View Answer

Question 82

Which of the following is a batch furnace?

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

View Answer

Question 83

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

View Answer

Question 84

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 85

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 86

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 87

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 88

Regenerators are used for waste heat recovery in

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

View Answer

Question 89

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 90

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

View Answer

Question 91

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

View Answer

Question 92

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 93

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 94

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 95

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 96

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 97

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

View Answer

Question 98

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 99

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 100

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

View Answer

Question 101

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 102

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 103

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 104

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 105

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 106

Regenerators are installed in

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

View Answer

Question 107

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 108

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 109

__________ furnace is not an electric furnace.

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

View Answer

Question 110

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

View Answer

Question 111

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

View Answer

Question 112

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 113

Reverberatory furnace is used for

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

View Answer

Question 114

Blast furnace stoves are meant for heating

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

View Answer

Question 115

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 116

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

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

View Answer

Question 117

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

View Answer

Question 118

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 119

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 120

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

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

View Answer

Question 121

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

View Answer

Question 122

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 123

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

View Answer

Question 124

Which furnace employs preheating, heating and soaking zones ?

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

View Answer

Question 125

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 126

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 127

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 128

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 129

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

View Answer

Question 130

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 131

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 132

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 133

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 134

Soaking pits are meant for heating steel

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

View Answer

Question 135

Maximum thermal efficiency of boiler may be about __________ percent.

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

View Answer

Question 136

Shaft furnaces are used for

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

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Question 137

Pulverised fuel fired furnaces employ __________ fuel firing.

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

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Question 138

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 139

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 140

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

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

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Question 141

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 142

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 143

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 144

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 145

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

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Question 146

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 147

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 148

__________ atmosphere is maintained inside an iron blast furnace.

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

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Question 149

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

View Answer

Question 150

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 151

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 152

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 153

Which furnace employs natural draft?

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

View Answer

Question 154

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 155

Large tonnage of refractory bricks are dried in a

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

View Answer

Question 156

Rotary kilns are used in the

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

View Answer

Question 157

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 158

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 159

Use of pulverised coal in boilers provides

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

View Answer

Question 160

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 161

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

View Answer

Question 162

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 163

Very high pressure boilers are usually __________ boilers.

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

View Answer

Question 164

Reducing atmosphere is maintained in a

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

View Answer

Question 165

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 166

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 167

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 168

Which furnace employs preheating, heating and soaking zones?

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

View Answer

Question 169

An example of indirectly heated furnace is the

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

View Answer

Question 170

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

View Answer

Question 171

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 172

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

View Answer

Question 173

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 174

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 175

Which of the following is a heat treatment furnace?

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

View Answer

Question 176

Cement Kiln is a

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

View Answer

Question 177

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 178

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 179

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 180

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 181

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 182

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 183

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 184

__________ is an indirectly heated furnace.

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

View Answer