Fuels and Combustion MCQs

Question 1

Calorific value of coke even gas produced by low temperature carbonisation of coal is about __________ kcal/Nm 3 .

Accepted Answer

6500

Answer

4000

Answer

2500

Answer

10000

Question 2

The calorific value of 'LPG' (50% propane + 50% butane) is about __________ kcal/Nm 3 .

Accepted Answer

25,000

Answer

5,000

Answer

10,000

Answer

15,000

Question 3

The calorific value of producer gas is around __________ kcal/Nm 3 .

Accepted Answer

1300

Answer

500

Answer

4500

Answer

9000

Question 4

In high temperature carbonisation of coal compared to low temperature carbonisation

Accepted Answer

H 2 content in the coke oven gas is more

Answer

Yield of ammonia is less

Answer

Aromatic content of tar is low

Answer

Calorific value of the coke oven gas is lower

Question 5

Dry air requirement for burning 1 Nm 3 of CO to CO 2 may be around __________ Nm 3 .

Accepted Answer

2.4

Answer

1.75

Answer

0.87

Answer

11.4

Question 6

Pure carbon is completely burnt in oxygen. The flue gas analysis is 70% CO 2 , 20% CO and 10% O 2 . The percent excess oxygen used is

Accepted Answer

0

Answer

20

Answer

12.5

Answer

10

Question 7

Steam is intermittently admitted into the fuel bed during the production of producer gas to

Accepted Answer

Minimise the chances of clinker formation

Answer

Convert CO to CO 2

Answer

Increase the combustion rate

Answer

Increase the gas production rate

Question 8

Pick out the wrong statement.

Accepted Answer

Ash is normally removed as

Answer

Percentage of ash in coke produced from medium coking coal is more than that in coal

Answer

The calorific value (kcal/Nm 3 ) of coke oven gas reduces on removal of hydrogen from it by cryogenic method

Answer

Coal based fertiliser plants in India at Talcher (Orissa) and Ramagundam (A.P.) employ Kopper-Totzek process of coal gasification

Question 9

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 & H 2 in the gas (due to the endothermic reaction represented by C + H 2 O = CO + H 2 )