Fuels and Combustion

A. Is equal to the heat of formation
B. Is always negative
C. Can’t be known without calculating it
D. Is always positive

A. CO2
B. SO2
C. Both A. & B.
D. Neither A. nor B.

A. Yield of ammonia is less
B. Aromatic content of tar is low
C. H2 content in the coke oven gas is more
D. Calorific value of the coke oven gas is lower

A. Reduces the coking time
B. Protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot
oven walls
C. Increases the loss of fine coal dust from the ovens when charging
D. None of these

A. Type (solid, liquid or gaseous)
B. Calorific value
C. Sulphur content
D. Ignition temperature

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

A. Main constituents of LPG are propane and butane
B. C.V. of natural gas is about 10000 KCal/Nm3
C. C.V. of LPG is about 26000 kcal/Nm3 (11500 kcal/kg)
D. L.P.G. is lighter than air

A. Cokes of high reactivity are obtained from weakly coking coals
B. Cokes of high reactivity are obtained from strongly coking coals
C. Reactivity of coke is inversely proportional to its absolute density
D. Abrasion index of the coke is a measure of its hardness

A. Oxygen content decreases from lignite to bituminous coal as the coalification increases
B. The less the oxygen content, better is the coal, as it reduces the calorific value
C. With increase in oxygen content, moisture holding capacity of coal increases and the caking power decreases
D. All A., B. and C.

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