Fuels and Combustion
For the case of a fuel gas undergoing combustion with air, if the air/fuel ratio is increased, the adiabatic flame temperature will

Increase or decrease depending on the fuel type
Decrease
Not change
Increase

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Fuels and Combustion
A good metallurgical coke

Should have high porosity
Should be brittle
Must contain moderate quantities of ash, moisture, sulphur and volatile matters
Should have low fusion point of its ash

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Fuels and Combustion
A coal with high ash content is undesirable, as

It is abrasive to the coal pulveriser (ie.g. ball mill) and the combustion chamber
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
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
All of these

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