Fuels and Combustion

381.Turndown ratio of a gas burner is equal to the

1. Maximum to minimum heat input ratio
2. Maximum to minimum permissible gas flow rate
3. Both (A) & (B)
4. Minimum to maximum heat input ratio

View answer

382.Ultimate analysis of coal determines its _________ content.

1. Carbon, hydrogen, nitrogen & sulphur
2. Carbon, ash, sulphur & nitrogen
3. Carbon, sulphur, volatile matter & ash
4. Carbon, volatile matter, ash & moisture

View answer

383.Undercharging of coal in the by-product coke ovens results in

1. Decrease in the c.v. of coke oven gas
2. Increase in its throughput
3. Increase in the c.v. of coke oven gas
4. No change in the c.v. of coke oven gas

View answer

384.Use of excess of combustion air in the combustion of fuels results in

1. Heat losses
2. Long flame
3. Condensation of water vapour from the fuel gas
4. None of these

View answer

385.Use of preheated air for combustion of fuel in the furnace, increases the

1. Scale losses of the furnace stock
2. Calorific value of the fuel
3. Flame temperature
4. None of these

View answer

386.Use of pulverised coal in boiler furnace provides

1. High calorific value
2. Better combustion
3. Smokeless burning
4. Less erosion on furnace walls

View answer

387.Very _________ coals are completely devoid of cokability i.e., it is non-coking.

1. Young
2. Mature
3. Both 'a' & 'b'
4. Neither 'a' nor 'b'

View answer

388.Volatile matter content in coking coal may be about _________ percent.

1. 1
2. 7
3. 22
4. 46

View answer

389.Volatile matter content of metallurgical coke may be around _________ percent.

1. 43862
2. 42278
3. 22-26
4. 30-33

View answer

390.Volumetric ratio of N₂ to O₂ in dry atmospheric air is

1. 0.21
2. 3.76
3. 4.76
4. 0.79

View answer