A. Is the removal of carbon from iron carbide (Fe3C)
B. Affects its crystalline structure
C. Is favoured by CO2
D. All A., B. and C.
Related Mcqs:
- In a furnace, the heat taken by the charge/stock and the heat lost to the furnace structure & flue gases depends on the__________________?
A. Rate of firing and emissivity of flame
B. Thermal conductivity of the charge & structural materials of furnace
C. Nature of process; whether batch, continuous or intermittent
D. All A., B. and C. - In salt bath furnace, heat is transferred to the charge mainly by __________________?
A. Conduction
B. Convection
C. Radiation
D. None of these - Design of waste heat boiler for recovery of waste heat from furnace gases depends upon the_________________?
A. Quantity & temperature of waste gas
B. Dust concentration & nature of dust in waste gas
C. Corrosive nature of the waste gas
D. All A., B. and C. - In a heating process, a heat flow diagram in which the quantities of heat in the various items of a heat balance are represented by the width of a band is called the__________________?
A. Ostwald chart
B. Cox chart
C. Sankey diagram
D. None of these - Thermal efficiency of a limestone calcination rotary kiln may be around ______________ percent?
A. 20
B. 40
C. 65
D. 80 - Circulation of gases in furnace is caused by the_________________?
A. Change in volume during a change of temperature
B. Difference in density between hot and cold gases
C. Furnace pressure in conjunction with draft in flues
D. All A., B. and C. - 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 - Ceramic coating material for furnace refractory, which increases its emissivity and thus the radiation heat transfer rate in the furnace, comprises of_________________?
A. Graphite powder
B. Thoria
C. Zircon powder
D. Beryllium - 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 - 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
