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
Correct Answer
in between 37 & 71%
Fuels and Combustion problems
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1. 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.
10. 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.