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

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
by

1 Answer

Answer :

(C) Excess air has been used for combustion
by

Related questions

A sample of natural gas containing 80% methane (CH4 ) and rest nitrogen (N2 ) is burnt with 20% excess air. With 80% of the combustibles producing CO2 and the remainder going to CO, the Orsat analysis in volume percent is (A) CO2 : 6.26, CO : 1.56, O2 : 3.91, H2O :15.66, N2 : 72.60 (B) CO2 : 7.42, CO : 1.86, O2 : 4.64, N2 :86.02 (C) CO2 : 6.39, CO : 1.60, O2 : 3.99, H2O:25.96, N2 :72.06 (D) CO2 : 7.60, CO : 1.90, O2 : 4.75, N2 : 85.74

Description : A sample of natural gas containing 80% methane (CH4 ) and rest nitrogen (N2 ) is burnt with 20% excess air. With 80% of the combustibles producing CO2 and the remainder going to CO, the Orsat analysis in volume percent is (A) CO2 : 6 ... 96, N2 :72.06 (D) CO2 : 7.60, CO : 1.90, O2 : 4.75, N2 : 85.74

Last Answer : (B) CO2 : 7.42, CO : 1.86, O2 : 4.64, N2 :86.02

If CO2 is not fully absorbed by the KOH solution meant for its absorption in the orsat apparatus, it will appear as (A) O2 (B) CO (C) N2 (D) SO2

Description : If CO2 is not fully absorbed by the KOH solution meant for its absorption in the orsat apparatus, it will appear as (A) O2 (B) CO (C) N2 (D) SO2

Last Answer : (D) SO2

Orsat apparatus(A) Gives flue gas analysis on dry basis (B) Determines N2 in flue gas indirectly (C) Can’t determine CO in flue gas, if it is < 0.2% (D) All (A), (B) & (C)

Description : Orsat apparatus (A) Gives flue gas analysis on dry basis (B) Determines N2 in flue gas indirectly (C) Can’t determine CO in flue gas, if it is < 0.2% (D) All (A), (B) & (C)

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

Orsat apparatus is meant for (A) Gravimetric analysis of flue gas (B) Finding out combustion efficiency (C) Direct determination of nitrogen in flue gas by absorbing it in ammoniacal cuprous chloride (D) None of these

Description : Orsat apparatus is meant for (A) Gravimetric analysis of flue gas (B) Finding out combustion efficiency (C) Direct determination of nitrogen in flue gas by absorbing it in ammoniacal cuprous chloride (D) None of these

Last Answer : (D) None of these

A carbonaceous fuel (containing no H2 or hydrocarbons) is burnt and the resulting flue gas contains 21% CO2 . It means that (A) 21% excess air has been used for combustion (B) 21% excess oxygen has been used for combustion (C) Complete combustion of fuel has taken place (D) No excess air has been used for combustion

Description : A carbonaceous fuel (containing no H2 or hydrocarbons) is burnt and the resulting flue gas contains 21% CO2 . It means that (A) 21% excess air has been used for combustion (B) 21% excess oxygen has ... (C) Complete combustion of fuel has taken place (D) No excess air has been used for combustion

Last Answer : (C) Complete combustion of fuel has taken place

The average molecular weight of a flue gas having the composition by volume as CO2 = 25%, O2 = 25%, N2 = 50% will be (A) 27.6 (B) 23 (C) 47.3 (D) 42.9

Description : The average molecular weight of a flue gas having the composition by volume as CO2 = 25%, O2 = 25%, N2 = 50% will be (A) 27.6 (B) 23 (C) 47.3 (D) 42.9

Last Answer : (B) 23

The pyrogallol solution used in Orsat apparatus can absorb (A) Only O2 (B) Both O2 and CO2 (C) Both O2 and CO (D) All CO, CO2 , and O2

Description : The pyrogallol solution used in Orsat apparatus can absorb (A) Only O2 (B) Both O2 and CO2 (C) Both O2 and CO (D) All CO, CO2 , and O2

Last Answer : (B) Both O2 and CO2

The cuprous chloride used in orsat apparatus can absorb (A) Only CO (B) Both CO and CO2(C) Both CO and O2(D) All CO, CO2, and O2

Description : The cuprous chloride used in orsat apparatus can absorb (A) Only CO (B) Both CO and CO2 (C) Both CO and O2 (D) All CO, CO2 , and O2

Last Answer : (D) All CO, CO2 , and O2

Nitrogen present in the flue gas is determined in the Orsat apparatus by absorbing it in (A) KOH (B) Ammoniacal cuprous chloride (C) Pyrogallol solution(D) None of these

Description : Nitrogen present in the flue gas is determined in the Orsat apparatus by absorbing it in (A) KOH (B) Ammoniacal cuprous chloride (C) Pyrogallol solution (D) None of these

Last Answer : (D) None of these

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

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

Description : 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 ... coal is called its 'fuel ratio' (D) Calorific value of natural gas is more than that of LPG

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

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)

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

Flue gas obtained on complete combustion of pure acetylene (a hydrocarbon fuel) will contain (A) CO (B) CO2 (C) H2O (D) Both (B) & (C)

Description : Flue gas obtained on complete combustion of pure acetylene (a hydrocarbon fuel) will contain (A) CO (B) CO2 (C) H2O (D) Both (B) & (C)

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

The sequence of absorption in flue gas analysis by Orsat's apparatus is respectively (A) CO2 , O2 , CO (B) CO, O2 , CO2 (C) CO2 , CO, O2

Description : The sequence of absorption in flue gas analysis by Orsat's apparatus is respectively (A) CO2 , O2 , CO (B) CO, O2 , CO2 (C) CO2 , CO, O2

Last Answer : (A) CO2 , O2 , CO

When incomplete combustion loss is high, the flue gas analysis shows large amount of (A) CO2 (B) CO (C) O2 (D) C

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Last Answer : (B) CO

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

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Last Answer : (B) % of O2 in

To maximize the combustion efficiency, which of the following in the flue gas needs to be done? a) maximize O2 b) maximize CO2 c) minimize CO2 d) maximize CO

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Last Answer : b) maximize CO2

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

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) Increases

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

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Last Answer : (A) More of excess air

Oxygen content in a flue gas was found to be 4%. It implies that excess air used for combustion was around __________ percent. (A) 4 (B) 96 (C) 20 (D) 40

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Last Answer : (C) 20

A liquid/gaseous fuel containing hydrocarbons and high amount of sulphur is burnt with 40% excess air. The flue gas still contains large amount of carbon monoxide. This may be due to the (A) Presence of large quantity of hydrogen in the fuel (B) Low calorific value of the fuel (C) High sulphur content in the fuel (D) Lack of thorough mixing of fuel with air

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Last Answer : (D) Lack of thorough mixing of fuel with air

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Last Answer : (B) CO, H2 & CH4

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Volumetric ratio of N2 to O2 in dry atmospheric air is (A) 0.21 (B) 3.76 (C) 4.76 (D) 0.79

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Last Answer : (B) 3.76

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Description : KOH solution used in Orsat apparatus absorbs (A) CO2 (B) SO2 (C) Both (A) & (B) (D) Neither (A) nor (B)

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

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

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Last Answer : (B) Dry gas/stack gas loss

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Last Answer : (B) Complete combustion

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Description : Incomplete combustion of a fuel is characterised by the high __________ in the flue gas. (A) Smoke (B) Temperature (C) Oxygen (D) Carbon monoxide

Last Answer : (D) Carbon monoxide

Explain higher and lower calorific value of a coal having following composition by mass Carbon 81%,Hydrogen 7%, Oxygen 8%,Nitrogen 2.5%, sulphur 1.5% and remaining is ash

Description : Explain higher and lower calorific value of a coal having following composition by mass Carbon 81%,Hydrogen 7%, Oxygen 8%,Nitrogen 2.5%, sulphur 1.5% and remaining is ash

Last Answer : Carbon C = 81% = 0.81 Hydrogen = H2 = 7% = 0.07 Oxygen = O2 = 8% = 0.08 Nitrogen = N = 2.5% = 0.025 Sulphur = S =1.5% = 0.015 Ash = 2.5% = 0.025 Dulong's formula: H.C.V. of coal = 33800 C + 144500 ... = H.C.V.- 9H2 x 2442 KJ / Kg = 36187.5- 9 x 0.07 x 2442 L.C.V. of coal = 34649.04 KJ / Kg 

Pick out the wrong statement. (A) Theoretical flame temperature is the temperature attained by the products of combustion, when the fuel is burned without loss or gain of heat (B) Burning the fuel with theoretically required amount of pure oxygen results in attainment of maximum adiabatic flame temperature (C) Burning the fuel with excess pure oxygen results in maximum theoretical flame temperature (D) Adiabatic flame temperatures of actual combustions are always less than the maximum values

Description : Pick out the wrong statement. (A) Theoretical flame temperature is the temperature attained by the products of combustion, when the fuel is burned without loss or gain of heat (B) ... flame temperature (D) Adiabatic flame temperatures of actual combustions are always less than the maximum values

Last Answer : (C) Burning the fuel with excess pure oxygen results in maximum theoretical flame temperature

Oxygen trim control strategy __ a. continuously measures the oxygen content in the flue gas b. adjusts the combustion air flow c. Continually tuning the air-fuel mixture. d. All of above

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Last Answer : d. All of above

Pure carbon is completely burnt in oxygen. The flue gas analysis is 70%CO2 , 20%CO and 10%O2 . The percent excess oxygen used is (A) 20 (B) 12.5 (C) 0 (D) 10

Description : Pure carbon is completely burnt in oxygen. The flue gas analysis is 70%CO2 , 20%CO and 10%O2 . The percent excess oxygen used is (A) 20 (B) 12.5 (C) 0 (D) 10

Last Answer : (C) 0

In Orsat's apparatus, ammoniacal cuprous chloride is used for selectivity absorbing (A) CO (B) CO2 (C) O2 (D) H2O

Description : In Orsat's apparatus, ammoniacal cuprous chloride is used for selectivity absorbing (A) CO (B) CO2 (C) O2 (D) H2O

Last Answer : (A) CO

The maximum percentage of CO2 in a flue gas (from a carbonaceous fuel) can be(A) 21(B) 77(C) 79(D) 29

Description : The maximum percentage of CO2 in a flue gas (from a carbonaceous fuel) can be (A) 21 (B) 77 (C) 79 (D) 29

Last Answer : (A) 21

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Description : 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

Last Answer : (A) Computing the excess/deficiency of combustion air

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

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Last Answer : a) natural gas

In general, the limit of inflammability/explosion limit of fuel gases is widened by the (A) Increase in gas pressure (B) Increase in temperature (i.e. preheating) (C) Use of pure oxygen for combustion instead of air (D) All (A), (B) & (C)

Description : In general, the limit of inflammability/explosion limit of fuel gases is widened by the (A) Increase in gas pressure (B) Increase in temperature (i.e. preheating) (C) Use of pure oxygen for combustion instead of air (D) All (A), (B) & (C)

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