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

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

1 Answer

Answer :

Ans: Economizer
by

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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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Economizer is provided to utilize the flue gas heat for ___ a) preheating the boiler feed water b) preheating the stock c) preheating the combustion air d) preheating fuel

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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

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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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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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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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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

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State the location and function of i) Economizer ii) Feed water heater.

Description : State the location and function of i) Economizer ii) Feed water heater.

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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

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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

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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

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)

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

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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

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

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 waste gases coming out from gas turbine exhausts are of the order of: a) 370-540 b) 450 – 700 c) 700- 800 d) 250-440

Description : The waste gases coming out from gas turbine exhausts are of the order of: a) 370-540 b) 450 – 700 c) 700- 800 d) 250-440

Last Answer : 370-540

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)

Ringelmann chart is used for the measurement of the (A) Combustibles present in automobile exhaust (B) Smoke density from a chimney (C) Exhaust gas density (D) Flue gas temperature

Description : Ringelmann chart is used for the measurement of the (A) Combustibles present in automobile exhaust (B) Smoke density from a chimney (C) Exhaust gas density (D) Flue gas temperature

Last Answer : (B) Smoke density from a chimney

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

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

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

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

Description : 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 ... of fuel & air and infiltration of air (D) Use of excessive positive draft in the furnace

Last Answer : (C) Imperfect mixing of fuel & air and infiltration of air

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

Description : 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

Last Answer : (A) More of excess 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

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

What is an Economizer?

Description : What is an Economizer?

Last Answer : An economizer is a mechanical device which is used as a heat exchanger by preheating water by recovering residual heat from the flue gases in thermal power plant.

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)

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)

What is the function of boiler? • To burn the fuel in a confined closed system With the supply of air • To generate steam in varying pressure • To generate steam at constant pressure • To produce flue gases by burning fuel at a given pressure

Description : What is the function of boiler? • To burn the fuel in a confined closed system With the supply of air • To generate steam in varying pressure • To generate steam at constant pressure • To produce flue gases by burning fuel at a given pressure

Last Answer : • To generate steam at constant pressure

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

Description : 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

Last Answer : Option A

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

Description : 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

Last Answer : Option A

Fire tube boilers are those in which a) Flue gases pass through tubes and water around it b) Water passes through the tubes and flue gases around it c) Work is done during adiabatic expansion d) Change is enthalpy

Description : Fire tube boilers are those in which a) Flue gases pass through tubes and water around it b) Water passes through the tubes and flue gases around it c) Work is done during adiabatic expansion d) Change is enthalpy

Last Answer : a) Flue gases pass through tubes and water around it

Water tube boilers are those in which a) Flue gases pass through tubes and water around it b) Water passes through the tubes and flue gases around it c) Work is done during adiabatic expansion d) Change is enthalpy

Description : Water tube boilers are those in which a) Flue gases pass through tubes and water around it b) Water passes through the tubes and flue gases around it c) Work is done during adiabatic expansion d) Change is enthalpy

Last Answer : b) Water passes through the tubes and flue gases around it

The main advantage of forced draft over natural draft is that (A) Combustion of fuel is complete (B) Smaller height chimney can be used (C) Furnace control is easier (D) All (A), (B) & (C)

Description : The main advantage of forced draft over natural draft is that (A) Combustion of fuel is complete (B) Smaller height chimney can be used (C) Furnace control is easier (D) All (A), (B) & (C)

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

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

Description : 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

Last Answer : Heat wheels

Recovery of heat from dryer exhaust air is a typical application of: a) Waste heat recovery boiler b) Heat pump c) Heat wheel d) Economizer

Description : Recovery of heat from dryer exhaust air is a typical application of: a) Waste heat recovery boiler b) Heat pump c) Heat wheel d) Economizer

Last Answer : Heat wheel

Through what is feed water from hot-well is passed through, before entering steam and water drum in Lamont boiler? a. Evaporator tubes b. Economizer c. Distributor header d. Circulating pump

Description : Through what is feed water from hot-well is passed through, before entering steam and water drum in Lamont boiler? a. Evaporator tubes b. Economizer c. Distributor header d. Circulating pump

Last Answer : b. Economizer

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

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

Scaling of furnace stock is reduced by __________ in flue gas. (A) CO (B) H2 (C) High CO/CO2 (D) All (A), (B) & (C)

Description : Scaling of furnace stock is reduced by __________ in flue gas. (A) CO (B) H2 (C) High CO/CO2 (D) All (A), (B) & (C)

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

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)

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)

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)