Fuels and Combustion
Which of the following accounts for maximum energy loss in a boiler?

Unburnt carbon in flue gases
Flue gases
Incomplete combustion
Ash content in the fuel

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Fuels and Combustion
Fussain

All of these
Is non-coking, but when blended with highly coking coal, controls its swelling and produces high strength coke on carbonisation
Is friable, charcoal like substance
Has highest fixed carbon and lowest volatile matter content of all the four banded components of coal

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Fuels and Combustion
A good metallurgical coke

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

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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 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
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
All of these

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