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)

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)
by

1 Answer

Answer :

(D) All (A), (B) and (C)
by

Related questions

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 (A), (B) and (C

Description : 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 (A), (B) and (C

Last Answer : (D) All (A), (B) and (C

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 intermittent (D) All (A), (B) and (C)

Description : 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 & ... (C) Nature of process; whether batch, continuous or intermittent (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Calculate the recoverable waste heat (Q, in kCal/hour) from flue gases using the followingparameters: V (flow rate of the substance) 2000 m3/hr r (density of the flue gas): 0.9 kg/m3 Cp (specific heat of the substance): 0.20 kCal/kg oC DT (temperature difference): 120 oC h (recovery factor): 50% a. 21600 b. 43200 c. 25600 d. 34000

Description : Calculate the recoverable waste heat (Q, in kCal/hour) from flue gases using the followingparameters: V (flow rate of the substance) 2000 m3/hr r (density of the flue gas): 0.9 kg/m3 Cp (specific heat ... (temperature difference): 120 oC h (recovery factor): 50% a. 21600 b. 43200 c. 25600 d. 34000

Last Answer : 21600

Ingress of cold air in the furnaces through cracks, charging doors, openings etc(A) Reduces the flue gas temperature and makes the furnace atmosphereoxidising(B) Increases the load on the induced draft fan(C) Reduces the furnace draught(D) All (A), (B) and (C)

Description : 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 (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

The economiser is used in boilers to........ A]Increase thermal efficiency of boiler B]Economise on fuel C]Extract heat from the exhaust the gases D]Increase flue gas temperature

Description : The economiser is used in boilers to........ A]Increase thermal efficiency of boiler B]Economise on fuel C]Extract heat from the exhaust the gases D]Increase flue gas temperature

Last Answer : A]Increase thermal efficiency of boiler

Pick out the wrong statement. (A) A slight haze at the top of chimney indicates good combustion in the furnace (B) A bag filter incurs very small pressure drop and is very efficient for removal of submicronic dust particles from flue gases at very high temperature (C) Electrostatic precipitator is the most efficient dust collection equipment for removal of submicronic dust particles present in flue gas (D) None of these

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Last Answer : (B) A bag filter incurs very small pressure drop and is very efficient for removal of submicronic dust particles from flue gases at very high temperature

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

Description : 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

Last Answer : (A) Reduces its thermal efficiency

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 (A), (B) and (C)

Description : 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 (A), (B) and (C)

Last Answer : (B) Dust concentration & nature of dust in waste gas

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 (A), (B) and (C)

Description : 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 (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Which of the following furnaces will have maximum thermal efficiency? (A) Soaking pits (B) Walking beam reheating furnace (C) Boiler furnace (D) Rotary kilns

Description : Which of the following furnaces will have maximum thermal efficiency? (A) Soaking pits (B) Walking beam reheating furnace (C) Boiler furnace (D) Rotary kilns

Last Answer : (C) Boiler furnace

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

Description : 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

Last Answer : (C) Radiation

Furnace aerodynamics is related to the __________ in the furnace. (A) Movement of gases (B) Measurement of flue gas volume (C) Temperature control

Description : Furnace aerodynamics is related to the __________ in the furnace. (A) Movement of gases (B) Measurement of flue gas volume (C) Temperature control

Last Answer : (A) Movement of gases

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 (A), (B) and (C)

Description : 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 (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Find false statement about effect of sulphur in fuel? (A) It has heating value (B) It helps in electrostatic precipitation of ash in flue gases (C) It leads to corrosion of air heaters, ducting, etc. if flue gas exit temperature is low (D) It erodes furnace walls

Description : Find false statement about effect of sulphur in fuel? (A) It has heating value (B) It helps in electrostatic precipitation of ash in flue gases (C) It leads to corrosion of air heaters, ducting, etc. if flue gas exit temperature is low (D) It erodes furnace walls

Last Answer : (D) It erodes furnace walls

Higher efficiency in the combustion of solid fuel cannot be achieved by (A) Proper fuel preparation (B) Keeping the flue gas exhaust temperature very high (C) Adopting efficient-fuel firing technique & equipment (D) Supplying correct quantity of combustion air

Description : Higher efficiency in the combustion of solid fuel cannot be achieved by (A) Proper fuel preparation (B) Keeping the flue gas exhaust temperature very high (C) Adopting efficient-fuel firing technique & equipment (D) Supplying correct quantity of combustion air

Last Answer : (B) Keeping the flue gas exhaust temperature very high

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

Description : 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

Last Answer : (B) Regenerator

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 (A), (B) and (C

Description : 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 (A), (B) and (C

Last Answer : (D) All (A), (B) and (C

White flue gas (resembling steam) coming out of the chimney of a thermal power plant indicates that the fuel used in the boiler furnace is (A) Tar (B) Coke oven gas (C) Pitch (D) Pulverised coke

Description : White flue gas (resembling steam) coming out of the chimney of a thermal power plant indicates that the fuel used in the boiler furnace is (A) Tar (B) Coke oven gas (C) Pitch (D) Pulverised coke

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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

Description : 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

Last Answer : (B) Oxygen in the flue gas

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

Description : 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

Last Answer : (A) Type of fuels viz. solid, liquid or gaseous

Advantages of fluidised bed combustion are (A) Reduced NOx formation in flue gas (B) Lower furnace operating temperature (C) High heat transfer rate (D) All (A), (B) & (C)

Description : Advantages of fluidised bed combustion are (A) Reduced NOx formation in flue gas (B) Lower furnace operating temperature (C) High heat transfer rate (D) All (A), (B) & (C)

Last Answer : (D) All (A), (B) & (C)

The main drawback of supplying more excess air in the combustion of fuel is the (A) Excessive power requirement of air blower (B) Enhanced sensible heat loss in the flue gas (C) Intermittent and uncontrolled combustion of the fuel (D) High exit flue gas temperature from the furnace

Description : The main drawback of supplying more excess air in the combustion of fuel is the (A) Excessive power requirement of air blower (B) Enhanced sensible heat loss in the flue gas (C) Intermittent and uncontrolled combustion of the fuel (D) High exit flue gas temperature from the furnace

Last Answer : (B) Enhanced sensible heat loss in the flue gas

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 (A), (B) and (C)

Description : 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 (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of thermal conductivity 0.14 W/m.K and thickness __________ metre. (A) 0.01 (B) 0.1 (C) 0.25 (D) 0.5

Description : A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of ... and thickness __________ metre. (A) 0.01 (B) 0.1 (C) 0.25 (D) 0.5

Last Answer : (B) 0.1

Which of these is an output of a ‘Furnace’? a. Fuel gas b. Cool Air c. Flue gases d. Water Vapor

Description : Which of these is an output of a ‘Furnace’? a. Fuel gas b. Cool Air c. Flue gases d. Water Vapor

Last Answer : c. Flue gases

High sulphur content in a fuel __________ of the flue gases. (A) Decreases the dew point (B) Increases the dew point (C) Reduces the combustion efficiency by limiting the permissible temperature reduction (D) Both (B) and (C)

Description : High sulphur content in a fuel __________ of the flue gases. (A) Decreases the dew point (B) Increases the dew point (C) Reduces the combustion efficiency by limiting the permissible temperature reduction (D) Both (B) and (C)

Last Answer : (D) Both (B) and (C)

Too much of excess air in combustion results in high (A) Fuel consumption for the same heat load (B) Stack gas temperature (C) Percentage of oxygen in flue gases (D) All (A), (B) and (C)

Description : Too much of excess air in combustion results in high (A) Fuel consumption for the same heat load (B) Stack gas temperature (C) Percentage of oxygen in flue gases (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Flue gases coming out from furnace is first going through a) Turbine b) Economizer c) Air pre-heater d) Chimney

Description : Flue gases coming out from furnace is first going through a) Turbine b) Economizer c) Air pre-heater d) Chimney

Last Answer : Ans: Economizer

The most serious disadvantage of an orificemeter is that (A) It is not very accurate (B) It is very costly (C) Most of the pressure drop is not recoverable (D) It is not suitable for measuring gas flow

Description : The most serious disadvantage of an orificemeter is that (A) It is not very accurate (B) It is very costly (C) Most of the pressure drop is not recoverable (D) It is not suitable for measuring gas flow

Last Answer : (C) Most of the pressure drop is not recoverable

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

Description : 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

Last Answer : (D) None of these

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

Description : 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

Last Answer : (D) High pressure boiler

Incomplete combustion of fuel in the furnace is judged by high __________ of the flue gases. (A) CO content (B) Dew point (C) CO2 content (D) O2 content

Description : Incomplete combustion of fuel in the furnace is judged by high __________ of the flue gases. (A) CO content (B) Dew point (C) CO2 content (D) O2 content

Last Answer : (A) CO content

Most of the phosphorous present in the blast furnace burden enters into (A) Hot metal (B) Flue gases (C) Slag (D) Refractory lining

Description : Most of the phosphorous present in the blast furnace burden enters into (A) Hot metal (B) Flue gases (C) Slag (D) Refractory lining

Last Answer : (A) Hot metal

Pitch creosote mixture (PCM) as compared to furnace oil is a better fuel, because its (A) Emissivity factor is higher (B) Sulphur content is lower (C) Flue gas has lower dew point thereby facilitating more waste heat recovery (D) All (A), (B) and (C)

Description : Pitch creosote mixture (PCM) as compared to furnace oil is a better fuel, because its (A) Emissivity factor is higher (B) Sulphur content is lower (C) Flue gas has lower dew point thereby facilitating more waste heat recovery (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

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 (A), (B) and (C)

Description : 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 (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

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 ofcomplete combustion of(A) Furnace oil with air(B) Furnace oil with oxygen(C) Blast furnace gas with air(D) Blast furnace gas with oxygen

Description : 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 ofcomplete combustion of (A) Furnace oil with air (B) Furnace oil with oxygen (C) Blast furnace gas with air (D) Blast furnace gas with oxygen

Last Answer : (C) Blast furnace gas with air

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

Description : 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

Last Answer : (B) Flame temperature

Flue gas outlet temperature from the chimney of any furnace should be ideally about __________ °C. (A) 50 (B) 100 (C) 150

Description : Flue gas outlet temperature from the chimney of any furnace should be ideally about __________ °C. (A) 50 (B) 100 (C) 150

Last Answer : (C) 150

With increase in C/H ratio of a fuel, the dew point of flue gases (A) Increases (B) Decreases (C) Remain same (D) May increase or decrease; depends on the type of fuel

Description : With increase in C/H ratio of a fuel, the dew point of flue gases (A) Increases (B) Decreases (C) Remain same (D) May increase or decrease; depends on the type of fuel

Last Answer : (B) Decreases

A composite flat wall of a furnace is made of two materials 'A' and 'B'. The thermal conductivity of 'A' is twice of that of material 'B', while the thickness of layer of 'A' is half that of B. If the temperature at the two sides of the wall are 400 and 1200°K, then the temperature drop (in °K) across the layer of material 'A' is (A) 125 (B) 133 (C) 150 (D) 160

Description : A composite flat wall of a furnace is made of two materials 'A' and 'B'. The thermal conductivity of 'A' is twice of that of material 'B', while the thickness of layer of 'A' is half that of B. If the temperature ... drop (in °K) across the layer of material 'A' is (A) 125 (B) 133 (C) 150 (D) 160

Last Answer : (D) 160

The amount of combustible escaping unconsumed 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)

Description : The amount of combustible escaping unconsumed 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 ... , by acceleration or by change of direction) (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Combustion of pulverised coal compared to the lumpy coal (A) Provides better control of furnace temperature (B) Facilitates combustion with lower excess air (C) Provides higher thermal efficiency & flame temperature (D) All (A), (B) & (C)

Description : Combustion of pulverised coal compared to the lumpy coal (A) Provides better control of furnace temperature (B) Facilitates combustion with lower excess air (C) Provides higher thermal efficiency & flame temperature (D) All (A), (B) & (C)

Last Answer : (D) All (A), (B) & (C)

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

Description : 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

Last Answer : (B) Sintering machine

Thermocol (expanded polystyrene) is not used for (A) Low temperature thermal insulation as in refrigerator and air conditioners (B) Acoustic control and ceiling for building (C) High temperature thermal insulation in furnaces (D) Packing of delicate electronic gadgets

Description : Thermocol (expanded polystyrene) is not used for (A) Low temperature thermal insulation as in refrigerator and air conditioners (B) Acoustic control and ceiling for building (C) High temperature thermal insulation in furnaces (D) Packing of delicate electronic gadgets

Last Answer : (C) High temperature thermal insulation in furnaces

Preheating of a gaseous fuel results in increased (A) Flame length (B) Flame temperature (C) Quantity of flue gas

Description : Preheating of a gaseous fuel results in increased (A) Flame length (B) Flame temperature (C) Quantity of flue gas

Last Answer : (B) Flame temperature

Efficiency of the combustion of a fuel is judged by the __________ the flue gas. (A) % of CO2 in (B) % of O2 in (C) Temperature of (D) Colour of

Description : Efficiency of the combustion of a fuel is judged by the __________ the flue gas. (A) % of CO2 in (B) % of O2 in (C) Temperature of (D) Colour of

Last Answer : (B) % of O2 in

Natural draft created by the chimney depends upon (A) Temperature of the flue gas (B) Its height (C) Both (A) & (B) (D) Neither (A) nor (B)

Description : Natural draft created by the chimney depends upon (A) Temperature of the flue gas (B) Its height (C) Both (A) & (B) (D) Neither (A) nor (B)

Last Answer : (C) Both (A) & (B)

Flue gas discharge velocity through chimney of a big thermal power plant may be around __________ m/sec. (A) 0.5 (B) 10 (C) 50 (D) 500

Description : Flue gas discharge velocity through chimney of a big thermal power plant may be around __________ m/sec. (A) 0.5 (B) 10 (C) 50 (D) 500

Last Answer : (B) 10

______ Oilfield of India has the largest quantity of recoverable reserves. (a) Moran Oilfield (b) Mumbai High (off shore) Oilfield (c) Ankaleshwar Oilfield (d) Naharkatiya Oilfield

Description : ______ Oilfield of India has the largest quantity of recoverable reserves. (a) Moran Oilfield (b) Mumbai High (off shore) Oilfield (c) Ankaleshwar Oilfield (d) Naharkatiya Oilfield

Last Answer : Ans: (b)

LSHS is a type of furnace oil, which (A) Is more viscous than high viscosity furnace oil (HVFO) (B) Stands for low sulphur heavy stock (C) Is an ideal fuel for metallurgical furnaces due to its lower sulphur content (< 1%(D) All (A), (B) and (C))

Description : LSHS is a type of furnace oil, which (A) Is more viscous than high viscosity furnace oil (HVFO) (B) Stands for low sulphur heavy stock (C) Is an ideal fuel for metallurgical furnaces due to its lower sulphur content (< 1%) (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)