Pulverized Coal-Fired Boiler

A pulverized coal fired boiler generates thermal energy by grinding coal to a fine powder and blowing it, mixed with air, into the firebox, where it ignites much like fuel injection in an engine. Hot air of around six hundred fifty degrees Fahrenheit both dries and helps pulverize the coal between grinding mechanisms before it is blown to a burner in the boiler, and the resulting ash is recovered partly as bottom ash in the furnace and partly as fly ash carried off with the exhaust gases. This design dominates coal fired power stations, providing the steam that drives large turbines, with efficiency ranging from about thirty seven percent in subcritical plants to about forty percent in supercritical plants and forty two to forty five percent in ultra supercritical plants, depending on operating temperature and pressure.