Fuels and Combustion MCQs

Question 1

Coke compared to the coal from which it has been made, contains

Accepted Answer

All of the above

Answer

Less volatile matter

Answer

More carbon

Answer

Greater percentage of ash

Question 2

Higher fuel combustion efficiency can not be achieved by

Accepted Answer

Reducing sulphur content in the fuel

Answer

Preheating of fuel gases & combustion air

Answer

Adopting proper fuel firing technique & fuel preparation

Answer

Supplying correct amount of combustion air

Question 3

Pick out the correct statement.

Accepted Answer

All of the above

Answer

Oxygen content decreases from lignite to bituminous coal as the coalification increases

Answer

The less the oxygen content, better is the coal, as it reduces the calorific value

Answer

With increase in oxygen content, moisture holding capacity of coal increases and the caking power decreases

Question 4

Higher efficiency in the combustion of solid fuel can not be achieved by

Accepted Answer

Keeping the flue gas exhaust temperature very high

Answer

Proper fuel preparation

Answer

Adopting efficient-fuel firing technique & equipment

Answer

Supplying correct quantity of combustion air

Question 5

A coal gasifier opearating at 20 atm. (e.g. Lugri gasifier) as compared to one operating at atmospheric pressure (e.g. Kopper-Totzek or Winkler gasifier) will produce a gas having

Accepted Answer

Higher methane content and thus higher calorific value

Answer

Higher carbon monoxide content

Answer

Lower carbon dioxide content

Answer

None of these

Question 6

Which of the following has the highest gross calorific value?

Accepted Answer

Oil refinery gas

Answer

Blast furnace gas

Answer

Coke oven gas

Answer

Carburetted water gas

Question 7

Highly reactive coke have lower

Accepted Answer

Critical air blast (CAB) value

Answer

Porosity

Answer

Coke reactivity index (CRI)

Answer

Both B and C

Question 8

Which of the following accounts for maximum energy loss in a boiler?

Accepted Answer

Flue gases

Answer

Ash content in the fuel

Answer

Incomplete combustion

Answer

Unburnt carbon in flue gases

Question 9

Pulverised coal used in boiler firing need not have

Accepted Answer

High fusion point of its ash

Answer

Less moisture content

Answer

High bulk density

Answer

Lower ash content