Actual flame temperature is always lower than the adiabatic flame temperature, b

CuriousTab

CuriousTab

Home Aptitude

Discussion

Home ‣ Chemical Engineering ‣ Fuels and Combustion Comments

Question
Actual flame temperature is always lower than the adiabatic flame temperature, because there is
Options
A. no possibility of obtaining complete combustion at high temperature.
B. always loss of heat from the flame.
C. both (a) and (b).
D. neither (a) nor (b).

Correct Answer

both (a) and (b).

Fuels and Combustion problems

Search Results

1. Explosion limit of blast furnace gas is 37 to 71% gas in gas-air mixture. It means that the blast furnace gas will explode when burnt in a confined space, if its concentration in the gas-air mixture is __________ percent.
Options
A. < 37%
B. >71%
C. in between 37 & 71%
D. none of these

2. Which of the following accentuates clinker-ing trouble on furnace grate burning coal?
Options
A. Low reactivity of carbonised residue containing high proportions of iron & sulphur.
B. Low forced draught and fuel bed temperature.
C. Thick fire bed and preheated primary air.
D. All (a), (b) and (c).

6. A coal having high amount of volatile matter
Options
A. would require smaller combustion chamber.
B. produces very little of tar and gas on carbonisation.
C. ignites easily and burns with long smoky flame.
D. all (a), (b) and (c).

7. Higher percentage of ash in coal meant for the production of metallurgical grade coke
Options
A. decreases the hardness of coke.
B. decreases the abrasion resistance of coke.
C. causes brittleness in steel.
D. none of these.

8. Improper storage condition results in the weathering of coal and spontaneous combustion, which increases its
Options
A. caking index.
B. yield of carbonised products.
C. friability & oxygen content.
D. calorific value.

9. A coal with high ash content is undesirable, as
Options
A. it is abrasive to the coal pulveriser (ie.g. ball mill) and the combustion chamber.
B. the ash in molten condition gets absorbed in the pores of the refractory lining of the furnace and causes its spalling due to different co-efficient of expansion/contraction of the refractory and the ash.
C. the ash retains the sulphur & phosphorus and thus affects the quality of products in metallurgical furnace apart from increasing the slag volume. Besides, it may fuse and stick to the boiler tubes thereby reducing the heat transfer.
D. all (a), (b) and (c).

Comments

More in Chemical Engineering: