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
Description : 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 ... very high (C) Excess air has been used for combustion (D) Hydrogen is not present in the fuel
Last Answer : (C) Excess air has been used for combustion
Description : 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
Last Answer : b) maximize CO2
Description : When incomplete combustion loss is high, the flue gas analysis shows large amount of (A) CO2 (B) CO (C) O2 (D) C
Last Answer : (B) CO
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)
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
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
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
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)
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
Description : measures oxygen and temperature of the flue gas. a) Fuel efficiency monitor. b) Combustion analyzer. c) Contact thermometer. d) Infrared thermometer.
Last Answer : Combustion analyzer
Description : Acid dew point temperature (ADT) of a flue gas produced by the combustion of a fuel containing 1% sulphur may be about __________ °C. (A) 80 (B) 130 (C) 180 (D) 250
Last Answer : (B) 130
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
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
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
Description : Which instrument is used to monitor O2, CO in flue gas? (EA) a) Combustion analyser b) Power analyser c) Pyrometer d) Fyrite
Last Answer : Combustion analyser
Description : instrument is used to monitor O2, CO in flue gas (EA) a) Combustion analyzer b) Power analyzer c) Pyrometer d) Fyrite
Description : Which instrument is used to monitor O2, CO in flue gas? c)Combustion analyzer c) Pyrometer d)Power analyzer d) Fyrite
Description : 115. Which instrument is used to monitor O2, CO in flue gas? a) Combustion analyzer c) Pyrometer b) Power analyzer d) Fyrite
Description : __________ the exhaust gas is an indication of the incomplete combustion of fuel. (A) Low temperature of (B) High temperature of (C) High % of CO in (D) High % of CO2in
Last Answer : (C) High % of CO in
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
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)
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
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
Description : If oxygen content in the flue gas rises too high, fuel is being wasted by (A) Incomplete combustion (B) Dry gas/stack gas loss (C) Moisture loss (D) None of these
Last Answer : (B) Dry gas/stack gas loss
Description : During combustion of a gaseous fuel, the presence of a non-luminous flame is an indication of the (A) Incomplete combustion (B) Complete combustion (C) High oxygen in flue gas (D) None of these
Last Answer : (B) Complete combustion
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
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
Description : 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
Last Answer : preheating the boiler feed water
Description : 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
Last Answer : d. All of above
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
Description : The combustion reaction, C + O2 = CO2 , is (A) Exothermic (B) Endothermic (C) Autocatalytic
Last Answer : (A) Exothermic
Description : The combustion reaction, C + O2 = CO2 , is (A) Exothermic (B) Endothermic (C) Autocatalytic (D) None of these
Description : 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
Last Answer : (C) 20
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
Description : As the C/H ratio of the fuel increases, the amount of CO2 formed on combustion __________ for the same percentage of excess air. (A) Decreases (B) Increases (C) Remain same (D) May increase or decrease depending on the type of fuel
Last Answer : (B) Increases
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)
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
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
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
Description : Presence of nitrogen in combustion air does not reduce the (A) Amount of heat liberated (B) Flame temperature (C) Flue gas temperature (D) Any of the above
Last Answer : (A) Amount of heat liberated
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)
Description : 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 ... dust collection equipment for removal of submicronic dust particles present in flue gas (D) None of these
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
Description : Steam is intermittently admitted into the fuel bed during the production of producer gas to (A) Convert CO to CO2 (B) Increase the combustion rate (C) Increase the gas production rate (D) Minimise the chances of clinker formation
Last Answer : (D) Minimise the chances of clinker formation
Description : In order to maintain a reducing atmosphere in a furnace, it should have (A) No O2 in flue gas (B) CO in flue gas (C) High excess air (D) None of these
Last Answer : (B) CO in flue gas
Description : Degree of carbonisation of coal during coke making can be roughly judged by the __________ of the coke produced. (A) Colour (B) Moisture content (C) Ash content (D) Volatile matter
Last Answer : (D) Volatile matter
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
Description : 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)
Description : 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
Last Answer : (A) < 2
Description : Preheating of a gaseous fuel results in increased (A) Flame length (B) Flame temperature (C) Quantity of flue gas