Question

Which gas cooling is used in large generator units of steam plant?

(a) Sulfur dioxide

(b) Hydrogen

(c) Carbon dioxide

(d) Nitrogen

I had been asked this question by my school principal while I was bunking the class.

This interesting question is from Types of Fuels topic in section Steam Power Plant of Energy Engineering

Answer 1

The correct answer is (b) Hydrogen

For explanation: Hydrogen gas cooling is used for large generator units in steam plant. Because it has the highest heat transfer coefficient of any known heat transfer coefficient of any gas and for its low viscosity which reduces wind-age losses. This system requires special handling during start up, with air in the generator enclosure first displaced by carbon dioxide before filling with hydrogen. This ensures that the highly flammable hydrogen does not mix with oxygen in the air.