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)

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)
by

1 Answer

Answer :

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

Related questions

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In a low to medium temperature waste heat recovery system which of the device is most suitable a) Economiser b) Heat wheels c) air preheater d) Recuperator

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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

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In regenerative air preheater (as practised in heating of coke ovens), the heat is transferred (A) Through a metallic wall (B) By direct contact of hot flue gas with air (C) By heating an intermediate material (like chequor bricks) and then heating the air from this hot material (D) None of these

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Nellore to medium temperature waste heat recovery system the most suitable device is ------ a) Economizer b) Heat wheels c) Air preheater d) Recuperate d) Carbonate

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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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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

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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)

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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

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Last Answer : 21600

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Use of economiser in a boiler plant reduces the fuel consumption for steam generation by about __________ percent. (A) 1 (B) 10 (C) 30 (D) 50

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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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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)

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The biggest loss in the boiler is a) Moisture in fuel b) Dry flue gases c) Steam formation d) Unburnt carbon

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An economiser in a boiler........ A]Increases steam pressure. B]Increases steam flow C]Decreases fuel consumption D]Decreases steam pressure

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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

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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)

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

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

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Last Answer : (B) 10

Most efficient and suitable dust removal equipment for removal of fly￾ash from flue gas in a thermal power plant is the (A) Gravity settling chamber (B) Cyclone separator (C) Electrostatic precipitator (D) Bag filter

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'Utilities' in a chemical process plant includes compressed air, steam, water, electrical power, oxygen, acetylene, fuel gases etc. Utility costs for ordinary chemical process plants ranges roughly from __________ percent of the total product cost. (A) 1 to 5 (B) 10 to 20 (C) 25 to 35 (D) 35 to 45

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Last Answer : (B) 10 to 20

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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The function of an economiser in a boiler is to preheat the (A) Feedwater (B) Combustion air (C) Pulverised coal (D) Furnace oil

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Last Answer : (A) Feedwater

What kind of energy output is obtained from a ‘Steam Power Plant’? a. Heat energy b. Sound energy c. Electricity d. Thermal energy

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In large thermal power stations very fine particulates present in flue gas are removed by (A) Wet scrubber (B) Bag filter (C) Electrostatic precipitators (D) Dust catcher

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Last Answer : (C) Electrostatic precipitators

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

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

What is the function of Air preheater?

Description : What is the function of Air preheater?

Last Answer : Air pre heater is used to transfer heat from the flue gases to the air before it passes into the furnace for combustion thereby increasing the thermal efficiency of the process.

What Is The Use Of Air Preheater?

Description : What Is The Use Of Air Preheater?

Last Answer : Air pre heater is used to transfer heat from the flue gases to the air before it passes into the furnace for combustion. It is placed between the economizer and chimney. The overall efficiency of the plant may be increased by 10 per cent by the use of air preheater.

Steam condensate is recovered by steam traps and recycled for use as boiler feed water, because of its low (A) Hardness (B) Dissolved solids content (C) Suspended solids content (D) All (A), (B) and (C)

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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

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Last Answer : (D) It erodes furnace walls

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

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

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Last Answer : Ans: Economizer

Plutonium (A) Is recovered from spent fuel from thermal nuclear reactor (B) Has much lower melting point (640°C ) compared to thorium (1690°C) (C) Both (A) and (B) (D) Neither (A) nor (B)

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

Flue gas from the heating chamber of byproduct coke ovens is removed by (A) Forced draft fan (B) Induced draft fan (C) Steam ejector (D) Natural draft

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Last Answer : (D) Natural draft

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

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

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

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

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Last Answer : (B) Decreases

Which of the following accounts for maximum energy loss in a boiler? (A) Flue gases (B) Ash content in the fuel (C) Incomplete combustion (D) Unburnt carbon in flue gases

Description : Which of the following accounts for maximum energy loss in a boiler? (A) Flue gases (B) Ash content in the fuel (C) Incomplete combustion (D) Unburnt carbon in flue gases

Last Answer : (A) 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)

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Limestone powder is injected during pulverised coal burning in boilers to __________ the flue gases. (A) Reduce SO2 content in (B) Catalytically convert SO2 to SO3 in (C) Increase the dew point of (D) None of these

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Last Answer : (A) Reduce SO2 content in

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

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

Water-tube boiler is the one, in which (A) Water passes through tubes and flue gases around it (B) Tube carrying hot flue gases are immersed in a pool of water (C) Tubes are placed in vertical position (D) None of these

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Water-tube boiler is the one, in which (A) Water passes through tubes and flue gases around it (B) Tube carrying hot flue gases are immersed in a pool of water (C) Tubes are placed in vertical position (D) None of these

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What is the maximum percent of energy recovered if the steam is condensed before reintroduced to system? a) 25 b) 35 c) 45 d) 55

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