3237. Stack heat losses can be minimised by
Controlling the excess air
Oxygen enrichment of combustion air
Using low c.v. fuels
Maintaining proper draft in the furnace
✅ The correct answer is option A.
3241. Coke oven gas produced by high temperature carbonisation of coal (as compared to that produced by low temperature carbonisation), has
Higher calorific value
Lower hydrogen content
Both A & B
Neither A nor B
✅ The correct answer is option D.
3246. Coal is heated in presence of air to a temperature of about __________ °C, while determining its ash content for proximate analysis.
500
750
950
1100
✅ The correct answer is option B.
3252. Which of the following constituents of coal is the most important in the production of coke?
Moisture
Ash
Volatiles
Carbon
✅ The correct answer is option D.
3256. Overfire burning in a furnace is a phenomenon characterised by the
Supply of excess fuel
Supply of excess air
Burning of carbon monoxide and other incombustibles in upper zone of furnace by supplying more air
None of these
✅ The correct answer is option C.
3220. Short/intense flame is produced during combustion of gaseous fuel by using
High amount/current of combustion air
Low amount/current of combustion air
Preheated secondary air
Very little excess air
✅ The correct answer is option A.
3185. Porosity of silica bricks varies from __________ percent.
5 to 10
20 to 30
45 to 60
60 to 75
✅ The correct answer is option B.
3188. Magnesite refractories have low resistance to
attack by basic slag.
abrasion.
disintegration on sudden change of temperature.
both (b) and (c).
✅ The correct answer is option D.
3192. Skull is not formed on the carbon blocks in the hearth of a blast furnace, when it becomes cold, becaus of its
non-wetting characteristic.
high thermal conductivity.
high crushing strength.
none of these.
✅ The correct answer is option A.
3197. Magnesite chrome refractories
have better spalling resistance than chrome magnesite refractories.
have very low thermal co-efficient of expansion.
are not at all resistant to the corrosive action of iron oxide.
have very low (50 kg/cm2 ) cold crushing strength (C.C.S.), and can not be used in metalcase form.
✅ The correct answer is option A.