Sphericity of pulverised coal is (A) 1 (B) < 1 (C) > 1 (D) ∞

Sphericity of pulverised coal is
(A) 1
(B) < 1
(C) > 1
(D) ∞
by

1 Answer

Answer :

(B) < 1
by

Related questions

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

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

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

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

The function of an economiser in a boiler is to preheat the (A) Feedwater (B) Combustion air (C) Pulverised coal (D) Furnace oil

Description : The function of an economiser in a boiler is to preheat the (A) Feedwater (B) Combustion air (C) Pulverised coal (D) Furnace oil

Last Answer : (A) Feedwater

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

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

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)

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

Fuel used in B.F. stove is (A) Pulverised coal (B) Furnace oil (C) Blast furnace gas/mixed gas (D) Coke oven gas

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

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

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

Use of pulverised coal in boilers provides (A) Higher calorific value (B) Better combustion (C) Smokeless burning (D) Less erosion on furnace wall

Description : Use of pulverised coal in boilers provides (A) Higher calorific value (B) Better combustion (C) Smokeless burning (D) Less erosion on furnace wall

Last Answer : (B) Better combustion

Junker's calorimeter is used to determine the calorific value of (A) Pulverised coal (B) Gaseous fuels (C) Fuel oil (D) None of these

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

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

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

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

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

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

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

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) Requirement of large volume combustion chamber (B) Risk of explosion (C) Chances of clinker formation (D) Incomplete combustion of 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

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

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

Use of pulverised coal in boiler furnace provides (A) High calorific value (B) Better combustion (C) Smokeless burning (D) Less erosion on furnace walls

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

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 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

Last Answer : (A) Ash disposal problem

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)

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)

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

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

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

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

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)

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

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

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

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

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

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)

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)

A travelling grate stoker is meant for the efficient burning of __________ coal. (A) Caking (B) Pulverised (C) Non-caking (D) High ash

Description : A travelling grate stoker is meant for the efficient burning of __________ coal. (A) Caking (B) Pulverised (C) Non-caking (D) High ash

Last Answer : (C) Non-caking

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

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

Which of the following fuels is the best for burning on chain grate stoker? (A) Non-caking coal (B) Caking coal (C) Coking coal (D) Pulverised coal

Description : Which of the following fuels is the best for burning on chain grate stoker? (A) Non-caking coal (B) Caking coal (C) Coking coal (D) Pulverised coal

Last Answer : (A) Non-caking coal

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 matter coals are more suitable for making pulverised fuel (C) Regulation of furnace temperature and atmosphere (oxidising or reducing) is easily possible with pulverised fuel firing (D) None of these

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

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

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

Bulk density of pulverised coal may be about __________ kg/m3 . (A) 100 (B) 500 (C) 1000 (D) 1500

Description : Bulk density of pulverised coal may be about __________ kg/m3 . (A) 100 (B) 500 (C) 1000 (D) 1500

Last Answer : (B) 500

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

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

Limestone powder is injected during pulverised coal burning in boilers to __________ the flue gases. (A) Reduce SO2 content in (B) Catalytically convert SO2 to SO3 in (C) Increase the dew point of (D) None of these

Description : Limestone powder is injected during pulverised coal burning in boilers to __________ the flue gases. (A) Reduce SO2 content in (B) Catalytically convert SO2 to SO3 in (C) Increase the dew point of (D) None of these

Last Answer : (A) Reduce SO2 content in

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

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

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

The sphericity of a cylinder of 1 mm diameter and length 3 mm is (A) 0.9 (B) 0.78 (C) 0.6 (D) 0.5

Description : The sphericity of a cylinder of 1 mm diameter and length 3 mm is (A) 0.9 (B) 0.78 (C) 0.6 (D) 0.5

Last Answer : (A) 0.9

For a non-spherical particle, the sphericity (A) Is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle (B) Has the dimension of length (C) Is always less than 1 (D) Is the ratio of volume of a sphere having the same surface area as the particle to the actual volume of the particle

Description : For a non-spherical particle, the sphericity (A) Is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle (B) Has ... of volume of a sphere having the same surface area as the particle to the actual volume of the particle

Last Answer : (A) Is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle

If dp is the equivalent diameter of a non-spherical particle, Vp its volume and sp its surface area, then its sphericity is φs is defined by (A) φs = 6 Vp /dpsp (B) φs = Vp /dpsp (C) φs = 6 dpSp /Vp (D) φs = dpSp /Vp

Description : If dp is the equivalent diameter of a non-spherical particle, Vp its volume and sp its surface area, then its sphericity is φs is defined by (A) φs = 6 Vp /dpsp (B) φs = Vp /dpsp (C) φs = 6 dpSp /Vp (D) φs = dpSp /Vp

Last Answer : (A) φs = 6 Vp /dpsp

For raschig rings, the sphericity is (A) 0.5 (B) 1 (C) < 1

Description : For raschig rings, the sphericity is (A) 0.5 (B) 1 (C) < 1

Last Answer : (C) < 1

Sphericity is the ratio of the surface area of a spherical particle having the same volume as the particle to the surface area of the particle. Which of the following has the maximum value of sphericity? (A) Sphere(B) Cube(C) Cylinder (L/D = 1)(D) Raschig rings

Description : Sphericity is the ratio of the surface area of a spherical particle having the same volume as the particle to the surface area of the particle. Which of the following has the maximum value of sphericity? (A) Sphere (B) Cube (C) Cylinder (L/D = 1) (D) Raschig rings

Last Answer : (A) Sphere

The sphericity of a solid particle of cubical shape is (A) π (B) (π/6) 1/3 (C) (π/6) 1/2 (D) π/3

Description : The sphericity of a solid particle of cubical shape is (A) π (B) (π/6) 1/3 (C) (π/6) 1/2 (D) π/3

Last Answer : (B) (π/6) 1/3 (C) (π/6) 1/2

Sphericity of a cubical particle, when its equivalent diameter is taken as the height of the cube, is (A) 0.5 (B) 1 (C) √2 (D) √3

Description : Sphericity of a cubical particle, when its equivalent diameter is taken as the height of the cube, is (A) 0.5 (B) 1 (C) √2 (D) √3

Last Answer : (B) 1

Sphericity for a non-spherical particle is given by (where, V and S are volume and surface area respectively of one particle. and, D = equivalent diameter of particle). (A) 6.V/D.S(B) V/6D.S (C) D.S/V (D) V/D.S

Description : Sphericity for a non-spherical particle is given by (where, V and S are volume and surface area respectively of one particle. and, D = equivalent diameter of particle). (A) 6.V/D.S (B) V/6D.S (C) D.S/V (D) V/D.S

Last Answer : (B) V/6D.S (C) D.S/V (D) V/D.S

Sphericity of raschig ring (whose length and diameter are equal) is (A) > 1 (B) < 1 (C) 1 (D) 2

Description : Sphericity of raschig ring (whose length and diameter are equal) is (A) > 1 (B) < 1 (C) 1 (D) 2

Last Answer : (C) 1

Reciprocal of sphericity is termed as the (A) Specific surface ratio (B) Shape factor (C) Sauter diameter (D) Surface area per unit mass

Description : Reciprocal of sphericity is termed as the (A) Specific surface ratio (B) Shape factor (C) Sauter diameter (D) Surface area per unit mass

Last Answer : (B) Shape factor

Carbon black is pulverised in a (A) Hammer crusher (B) Ball mill (C) Roll crusher (D) Gyratory crusher

Description : Carbon black is pulverised in a (A) Hammer crusher (B) Ball mill (C) Roll crusher (D) Gyratory crusher

Last Answer : (B) Ball mill

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

Pulverised fuel fired furnaces employ __________ fuel firing. (A) Horizontal (B) Vertical (C) Tangential (D) All (A), (B) and (C)

Description : Pulverised fuel fired furnaces employ __________ fuel firing. (A) Horizontal (B) Vertical (C) Tangential (D) All (A), (B) and (C)

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

Hard pitch is used for making (A) Pulverised fuel (B) Perfumes (C) Insecticides (D) Plastics

Description : Hard pitch is used for making (A) Pulverised fuel (B) Perfumes (C) Insecticides (D) Plastics

Last Answer : (A) Pulverised fuel

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

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

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)

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

Which of the following is an adsorbent for removal of nitrogen oxides from gas/air? (A) Active carbon (B) Silica gel (C) Bog iron (iron oxide) (D) Pulverised limestone

Description : Which of the following is an adsorbent for removal of nitrogen oxides from gas/air? (A) Active carbon (B) Silica gel (C) Bog iron (iron oxide) (D) Pulverised limestone

Last Answer : (B) Silica gel