Description : The main function of primary air in pulverised coal fired burner is to (A) Burn CO to CO2 (B) Dry and transport the coal (C) Have proper combustion by supplying it around the burner (D) Preheat the tertiary air used for complete combustion of CO to CO2
Last Answer : (B) Dry and transport the coal
Description : Temperature of preheated air used for the transportation of pulverised coal through pipes to the burner of a boiler furnace is restricted to a maximum limit of about 300° C to avoid the (A) ... chamber (B) Risk of explosion (C) Chances of clinker formation (D) Incomplete combustion of coal
Last Answer : (B) Risk of explosion
Description : Use of pulverised coal in boiler furnace provides (A) High calorific value (B) Better combustion (C) Smokeless burning (D) Less erosion on furnace walls
Last Answer : (B) Better combustion
Description : Which of the following would require maximum amount of % excess air for complete combustion? (A) Coke oven gas (B) Furnace oil (C) Pulverised coal (D) Lump coal (fixed on chain grate)
Last Answer : (D) Lump coal (fixed on chain grate)
Description : Which of the following fuels is generally not used in thermal power plant boiler firing? (A) Furnace oil, light diesel oil and tar/PCM (B) Pulverised coking coal (C) Coal middling from washeries (D) B.F. gas, coke oven gas and L.D. converter gas
Last Answer : (B) Pulverised coking coal
Description : In case of pulverised coal fired steam boiler, the secondary air serves the main purpose of (A) Transportation of coal (B) Drying of coal (C) Combustion of coal by supplying it around the burner (D) Preheating the primary air
Last Answer : (C) Combustion of coal by supplying it around the burner
Description : Combustion of pulverised coal compared to the lumpy coal (A) Provides better control of furnace temperature (B) Facilitates combustion with lower excess air (C) Provides higher thermal efficiency & flame temperature (D) All (A), (B) & (C)
Last Answer : (D) All (A), (B) & (C)
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
Description : Coal is pulverised before burning in large capacity boiler furnaces mainly to (A) Ensure its complete combustion (B) Facilitate easy ash removal (C) Enhance its calorific value (D) Provide trouble free operation
Last Answer : (A) Ensure its complete combustion
Description : Use of pulverised coal in boilers provides (A) Higher calorific value (B) Better combustion (C) Smokeless burning (D) Less erosion on furnace wall
Description : The advantage of firing pulverised coal in the furnace lies in the fact, that it (A) Permits the use of high ash content coal (B) Permits the use of low fusion point ash coal (C) Accelerates the burning rate and economises on fuel combustion (D) All (A), (B) and (C)
Last Answer : (C) Accelerates the burning rate and economises on fuel combustion
Description : Size of the combustion chamber of a furnace depends upon the (A) Heat release rate of the fuel (B) Preheat temperature of fuel & air (C) Method of mixing the fuel & air (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : 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
Last Answer : (B) Regenerator
Description : The function of secondary combustion air is to (A) Pneumatically convey the pulverised coal (B) Completely burn the volatile matter (C) Burn the lumpy coal (D) None of these
Last Answer : (B) Completely burn the volatile matter
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 : Fuel used in B.F. stove is (A) Pulverised coal (B) Furnace oil (C) Blast furnace gas/mixed gas (D) Coke oven gas
Last Answer : (C) Blast furnace gas/mixed gas
Description : A coal with high ash content is undesirable, as (A) It is abrasive to the coal pulveriser (i.e. ball mill) and the combustion chamber (B) The ash in molten condition gets absorbed in the pores of the ... and stick to the boiler tubes thereby reducing the heat transfer (D) All (A), (B) and (C)
Description : 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
Last Answer : (B) Coke oven gas
Description : Combustion of pulverised coal as compared to that of lump coal (A) Develops a non-luminous flame (B) Develops a low temperature flame (C) Can be done with less excess air (D) Provides a lower rate of heat release
Last Answer : (C) Can be done with less excess ai
Description : Emission of dense white smoke out of the chimney of a thermal power plant is an indication of the use of (A) Less air for combustion (B) Correct amount of air for combustion (C) Too much air for combustion (D) Pulverised coal in boilers
Last Answer : (C) Too much air for combustion
Description : The excess air required for the combustion of pulverised coal is of the order of about __________ percent. (A) 5 (B) 15 (C) 30 (D) 45
Last Answer : (B) 15
Description : Pick out the wrong statement. (A) Pulverised fuel can be completely burnt with less percentage of excess air compared to lump coal (B) Low grade coal can be used, but generally high volatile ... and atmosphere (oxidising or reducing) is easily possible with pulverised fuel firing (D) None of these
Last Answer : (D) None of these
Description : Combustion of pulverised fuel (A) Requires larger combustion chamber than rich gaseous fuel (B) In a metallurgical furnace does not contaminate the product in the furnace by ash from fuel (C) Suppresses the discharge of fine dust and grit into atmosphere (D) All (A), (B) and (C)
Last Answer : (A) Requires larger combustion chamber than rich gaseous fuel
Description : Which of the following is the most important deterrents to an extended use of pulverised coal in boiler firing? (A) Ash disposal problem (B) Excessive fly ash discharge from the stack (C) Higher power consumption in its transportation (D) Erosion of induced draft fan blades
Last Answer : (A) Ash disposal problem
Description : Which of the following is the most important deterrents to an extended use of pulverised coal in boiler firing? (A) Ash disposal problem (B) Excessive fly-ash discharge from the stack (C) High power consumption in its transportation (D) Erosion of induced draft fan blades
Description : 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
Last Answer : (B) Bag filter
Description : Pulverised coal used in boiler firing need not have (A) Less moisture content (B) High fusion point of its ash (C) High bulk density (D) Lower ash conten
Last Answer : (B) High fusion point of its ash
Description : The advantages of firing pulverised coal in the furnace lies in the fact that, it (A) Permits the use of high ash content coal (B) Permits the use of low fusion point ash coal (C) Accelerates the burning rate and economises on fuel consumption (D) All (A), (B) and (C)
Last Answer : (C) Accelerates the burning rate and economises on fuel consumption
Description : The amount of combustible escaping unconsumed from the furnace, depends upon the (A) Air supplied and furnace temperature (B) Burner design (thoroughness of mixing versus stratification) (C) Air preheat and the flow of ... , by acceleration or by change of direction) (D) All (A), (B) and (C)
Description : Combustion of which fuels from following is source of heat for boiler 1. Wood 2. Coal 3. Oil 4. All of above
Last Answer : 4. All of above
Description : Which of the following is the combustion accessory of a boiler? • Fuel oil system • Gas system • Coal system • All of the above
Last Answer : • All of the above
Description : Amount of coal lost in ash particle, which is carried through the boiler system, depends upon the (A) Physical nature, ash content and fineness of the coal (B) Amount of excess air supplied and load on the boiler (C) Type of burner and combustion chamber (D) All (A), (B) and (C)
Description : Function of secondary air in pulverised coal firing is to (A) Transport the coal to the burner (B) Dry the coal (C) Ensure efficient burning of coal around the burner (D) Reduce primary air requirement
Last Answer : (C) Ensure efficient burning of coal around the burner
Description : 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
Last Answer : (B) 10
Description : An economiser in a boiler........ A]Increases steam pressure. B]Increases steam flow C]Decreases fuel consumption D]Decreases steam pressure
Last Answer : C]Decreases fuel consumption
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 : 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 : Efficient burning of anthracite coal requires (A) Low preheat of air (B) Fine grinding (C) High excess air (D) All (A), (B) and (C)
Last Answer : (B) Fine grinding
Description : Junker's calorimeter is used to determine the calorific value of (A) Pulverised coal (B) Gaseous fuels (C) Fuel oil (D) None of these
Last Answer : (B) Gaseous fuels
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 : Combustion of furnace oil in a furnace (soaking pit) with preheated combustion air at 400°C results in saving of about __________ percentfurnace oil as compared to its combustion with atmospheric air, if the flue gas outlet temperature from the soaking pit is 1200°C. (A) 5 (B) 60 (C) 20 (D) 40
Last Answer : (C) 20
Description : Furnace oil consumption in a furnace for a given duty employing preheated combination air (at 300°) may be reduced by about __________ percent as compared to the use of atmospheric combustion air. (A) 5 (B) 10 (C) 20 (D) 35
Description : Low NOx Combustion Technology Regulation in Japan for Coal Firing Boiler has reduced from 400 ppm to____ a. 100ppm b. 200ppm c. 300ppm d. 400ppm
Last Answer : Ans:- b. 200ppm
Description : Function of fusible plug in a boiler is to (A) Drain out water and sludge from the boiler during repair (B) Put off fire in the furnace when water level in the boiler falls to unsafe limit (C) Guard the boiler in case of abnormal rise in steam pressure (D) All (A), (B) & (C)
Last Answer : (B) Put off fire in the furnace when water level in the boiler falls to unsafe limit
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)
Description : Pulverised coal passing through 200 mesh screen has a diameter of 0.074 mm (74 micron). The same passing through 50 mesh screen will have a dia of __________ mm. (A) 0.007 (B) 0.30 (C) 50 (D) 0.014
Last Answer : (B) 0.30
Description : Coal is finally pulverised to 200 mesh size for burning in boilers by a (A) Hammer crusher (B) Ball mill (C) Roll crusher (D) Gyratory crusher
Last Answer : (B) Ball mill
Description : Sphericity of pulverised coal is (A) 1 (B) < 1 (C) > 1 (D) ∞
Last Answer : (B) < 1
Description : Grindability index of a coal is 100. It implies that the (A) Coal can be pulverised with great difficulty (B) Coal can't be pulverised (C) Coal can be easily pulverised (D) Power consumption in grinding the coal will be very high
Last Answer : (C) Coal can be easily pulverised