Steam Boilers, Engines, Nozzles and Turbines
Spontaneous combustion is a phenomenon in which

Coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combination of oxygen with coal
All the fuel burns instantaneously producing high energy release
Fuel burns with less air
Explosion in furnace

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Steam Boilers, Engines, Nozzles and Turbines
Equivalent evaporation of water is the evaporation for a feed water supply at 100°C

And its corresponding conversion into dry saturated steam at 100°C and 1.033 kg/cm²
And its corresponding conversion into dry steam at desired boiler pressure
Conversion into steam at the same pressure at which feed water is supplied
Conversion into steam at atmospheric condition

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