Fuels and Combustion MCQs

469 MCQs  — Chemical Engineering MCQs  (Page 25 of 47)

‘Wobbe index’ is a characteristic of__________________?
A. Solid fuels
B. Gaseous fuels
C. Liquid fuels
D. Fat coals
The optimum percentage of excess air for combustion depends upon the _______________ of the fuel?
A. Type (solid, liquid or gaseous)
B. Calorific value
C. Sulphur content
D. Ignition temperature
Presence of free moisture in coal during its high temperature carbonisation _____________________?
A. Reduces the coking time
B. Protects the volatile products from pyrolysis (cracking) in the presence of hot coke and hot
OveN walls
C. Increases the loss of fine coal dust from the ovens when charging
In high temperature carbonisation of coal compared to low temperature carbonisation ?
A. Yield of ammonia is less
B. Aromatic content of tar is low
C. H2 content in the coke oven gas is more
D. Calorific value of the coke oven gas is lower
The heat of combustion of a fuel___________________?
A. Is equal to the heat of formation
B. Is always negative
C. Can’t be known without calculating it
D. Is always positive
Which of the following is not increased by using preheated combustion air in place of ordinary air at room temperature ?
A. Calorific value of the fuel
B. Flame temperature achieved
C. Speed of combustion of fuel
D. Heat transfer rate to the stock in the furnace
A coal with high ash content___________________?
A. Has higher calorific value
B. Is harder and stronger
C. Is not subjected to washing
D. Has low quantity of mineral matter