3174. Yield of coke oven gas in low temperature carbonisation of coal is about __________ Nm³ /ton of dry coal.
60
160
500
750
✅ The correct answer is option B.
3142. Flue gas discharge velocity through chimney of a big thermal power plant may be around __________ m/sec.
0.5
10
50
500
✅ The correct answer is option B.
3145. Combustion of pulverised coal compared to the lumpy coal
Provides better control of furnace temperature
Facilitates combustion with lower excess air
Provides higher thermal efficiency & flame temperature
All of the above
✅ The correct answer is option D.
3148. Washing of coal does not reduce its
S & P content
Heating value
Fusion point of ash
None of these
✅ The correct answer is option D.
3107. Permeability of bricks is a measure of the
refractoriness.
melting point.
rate at which a fluid will pass through the pores.
expansion during heating.
✅ The correct answer is option C.
3110. Which is the most stable crystalline form of silica at room temperature ?
Quartz
Cristobalite
Tridymite
None of these
✅ The correct answer is option A.
3113. With increase in the alumina content in firebricks, its fusion point (refractoriness)
decreases linearly
remains unchanged
increases
decreases
✅ The correct answer is option C.
3119. An ideal refractory should have high
spalling rate
fusion point
shrinkage ability
none of these
✅ The correct answer is option B.
3124. The highest melting pure oxide (m.p. > 3000°C)is
thoria
alumina
beryllia
zirconia
✅ The correct answer is option A.
3128. Spalling of a refractory means its
softening.
fracture due to uneven expansion at high temperature.
resistancce to compressive loads.
resistance to chemical action of gases and molten fluxes.
✅ The correct answer is option B.