Fuels and Combustion MCQs

Question 1

Low temperature carbonisation of coal takes place at __________ °C.

Accepted Answer

700

Answer

300

Answer

1100

Answer

150

Question 2

High temperature carbonisation of coal takes place at __________ °C.

Accepted Answer

1100

Answer

2000

Answer

600

Answer

1600

Question 3

Actual flame temperature is always lower than the adiabatic flame temperature, because there is

Accepted Answer

Both A & B

Answer

No possibility of obtaining complete combustion at high temperature

Answer

Always loss of heat from the flame

Answer

Neither A nor B

Question 4

The ratio of maximum adiabatic flame temperature in air to that in pure oxygen is always

Accepted Answer

< 1

Answer

1

Answer

> 1

Answer

Unpredicatable

Question 5

Sometimes water is sprayed during coal charging in the coke oven, which helps in

Accepted Answer

All of the above

Answer

Prevention of clinker formation in the oven

Answer

Controlling the dust nuisance while charging the coal

Answer

Reducing the cracking of hydrocarbons in the gas and increasing the percentage of CO & H2 in the gas (due to the endothermic reaction represented by C + H2O = CO + H2)

Question 6

The main drawback of supplying more excess air in the combustion of fuel is the

Accepted Answer

Enhanced sensible heat loss in the flue gas

Answer

Excessive power requirement of air blower

Answer

Intermittant and uncontrolled combustion of the fuel

Answer

High exit flue gas temperature from the furnace

Question 7

Which of the following fuel gases has the highest calorific value ?

Accepted Answer

Liquefied petroleum gas (LPG)

Answer

Natural gas

Answer

Coal bed methane (CBM)

Answer

Sewage gas

Question 8

Which of the following has the highest calorific value?

Accepted Answer

Anthracite

Answer

Lignite

Answer

Sub-bituminous coal

Answer

Peat

Question 9

Which of the following coke has the least percentage of ash?

Accepted Answer

Petroleum coke

Answer

Beehive coke

Answer

Foundary coke

Answer

Metallurgical coke