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

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
by

1 Answer

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
by

Related questions

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Last Answer : (C) Electrostatic precipitator

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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Which of the following fine dust removal equipments is the most efficient? (A) Bag filter (B) Scrubber (C) Electrostatic precipitator (D) Cyclone separator

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The most efficient equipment for the removal of sub-micronic dust particles from blast furnace gas is the (A) Venturi atomiser (B) Gravity settling chamber (C) Electro-static precipitator (D) Cyclone separator

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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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Dust collection efficiency of electrostatic precipitator can be as high as 99.9%. Maximum temperature and pressure of dust laden gas that can be cleaned in an electrostatic precipitator is respectively. (A) 200°C and 5 atm (B) 1000°C and 10 atm (C) 500°C and 50 atm (D) 1000°C and 500 atm

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Which of the following does not discharge the dust collected as a dry solid? (A) Electrostatic precipitator (B) Wet scrubber (C) Bag filter (D) Gravity settling chamber

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Which of the following dust collection equipments is the least efficient (for sub-micronic particles)? (A) Dust catcher (gravity type) (B) Cyclone separator (C) Bag filter (D) Hollow wet scrubber

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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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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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Volumetric composition of flue gas analysed with the Orsat apparatus is : CO2 = 12%, O2 = 8%, CO = nil, N2 = 80%. This flue gas composition indicates that (A) Pure oxygen has been used for combustion (B) Nitrogen percentage in the fuel is very high (C) Excess air has been used for combustion (D) Hydrogen is not present in the fuel

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Last Answer : (C) Excess air has been used for combustion

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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Which of the following will be unsuitable for dust cleaning from flue gas at 400°C from a pulverised coal fired boiler? (A) Multicyclones (B) Bag filter (C) Wet scrubber (D) Hydrocyclones

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

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

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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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Pick out the wrong statement. (A) High concentration of oxygen in flue gas means high stack loss (B) Gaseous fuels require the least % excess air for complete combustion (C) The ratio of fixed carbon to volatile matter percentage in coal is called its 'fuel ratio' (D) Calorific value of natural gas is more than that of LPG

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Last Answer : (D) Calorific value of natural gas is more than that of LPG

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)

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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

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White smoke coming out of the chimney of a furnace indicates the useof(A) Low excess air(B) Very high excess air(C) Gaseous fuel in the furnace(D) Liquid fuel in the furnace

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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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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

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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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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

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

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Last Answer : (B) Flame temperature

Traces of liquid tar fog present in coke oven gas is separated using (A) Electrostatic precipitator (B) Cyclone separator (C) Strainer (D) None of these

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Traces of tar fog present in the coke oven gas is removed by (A) Cyclone separator (B) Wet packed scrubber (C) Electrostatic precipitator (D) Washing with monoethanolamine

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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

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Pick out the wrong statement. (A) Activity co-efficient is dimensionless. (B) In case of an ideal gas, the fugacity is equal to its pressure. (C) In a mixture of ideal gases, the fugacity of a component is equal to the partial pressure of the component. (D) The fugacity co-efficient is zero for an ideal gas

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Pick out the wrong statement. (A) In solvent extraction, the distribution co-efficient should be as large as possible for solvent economy (B) With increase in pressure, the solubility of gases in solvent increases at a fixed temperature (C) Decrease in Murphree plate efficiency is an indication of entrainment in distillation column (D) The capacity of a distillation column is maximum at total reflux

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Last Answer : (D) The capacity of a distillation column is maximum at total reflux

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

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Last Answer : (B) Smoke density from a chimney

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

Bag filter design is predominantly dependent on gas temperature, as it affects the gas density & viscosity and the selection of filtering material. The pressure drop in a bag filter is (A) Inversely proportional to viscosity of gas (B) Proportional to the viscosity & density of the gas (C) Proportional to the pressure of the gas (D) Both (B) and (C)

Description : Bag filter design is predominantly dependent on gas temperature, as it affects the gas density & viscosity and the selection of filtering material. The pressure drop in a bag filter is (A) Inversely proportional to ... the gas (C) Proportional to the pressure of the gas (D) Both (B) and (C)

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

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

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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

A packed tower compared to a plate tower for a particular mass transfer operation (A) Incurs smaller pressure drop (B) Allows installation of cooling coils (C) Is less costly when built in large sizes/diameters (D) Is more suitable, if suspended solids are present in fluid stream

Description : A packed tower compared to a plate tower for a particular mass transfer operation (A) Incurs smaller pressure drop (B) Allows installation of cooling coils (C) Is less costly when built in large sizes/diameters (D) Is more suitable, if suspended solids are present in fluid stream

Last Answer : (A) Incurs smaller pressure drop

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

Naphthalene is removed from coke oven gas by (A) Adsorbing on palladium (B) Absorbing in ethanolamine (C) Scrubbing with wash oil (D) Passing it through electrostatic precipitator

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Last Answer : (C) Scrubbing with wash oil

Pick out the wrong statement. (A) Superheated steam is preferably not used for process heating because of its low heat transfer film co-efficient (B) In a shell and tube heat exchanger, the shell pressure drop is maximum for orifice baffles (C) S.I. unit of fouling factor is Watt/m2 .°K (D) Longitudinal fins are used in extended surface heat exchangers, when the direction of fluid flow is parallel to the axis of the tube

Description : Pick out the wrong statement. (A) Superheated steam is preferably not used for process heating because of its low heat transfer film co-efficient (B) In a shell and tube heat exchanger ... surface heat exchangers, when the direction of fluid flow is parallel to the axis of the tube

Last Answer : (C) S.I. unit of fouling factor is Watt/m2 .°K

Pick out the wrong statement. (A) Addition of methane to the furnace atmosphere reduces decarburising by hydrogen (B) Nitrogen in presence of steam decor-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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Which among the following has the highest flue gas loss on combustion due to Hydrogen in the fuel? a) natural gas b) furnace oil c) coal d) light diesel oil

Description : Which among the following has the highest flue gas loss on combustion due to Hydrogen in the fuel? a) natural gas b) furnace oil c) coal d) light diesel oil

Last Answer : a) natural gas

Which of the following gas-liquid contacting devices incurs the least pressure drop for a particular duty? (A) Grid tray tower (B) Perforated tray tower (C) Wetted wall tower (D) Bubble cap tower

Description : Which of the following gas-liquid contacting devices incurs the least pressure drop for a particular duty? (A) Grid tray tower (B) Perforated tray tower (C) Wetted wall tower (D) Bubble cap tower

Last Answer : (D) Bubble cap tower

Black smoke coming out of the chimney of a furnace is an indication of the use of __________ in the furnace. (A) Low amount of excess combustion air (B) Large quantity of excess combustion air(C) Hydrocarbon fuel(D) Pulverised coal as fuel

Description : Black smoke coming out of the chimney of a furnace is an indication of the use of __________ in the furnace. (A) Low amount of excess combustion air (B) Large quantity of excess combustion air (C) Hydrocarbon fuel (D) Pulverised coal as fuel

Last Answer : (A) Low amount of excess combustion air

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)

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Pick out the wrong statement. (A) A particular chemical reaction is more temperature sensitive at low temperatures (B) A very high value of equilibrium constant, K (K >> 1) indicates that the reaction is practically irreversible in nature (C) The intercept of the Arrhenius plot is called the 'activation energy' (D) Non-ideal flow takes place in reactors due to recycling, channeling or by creation of stagnant regions

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