When we use saturated steam for heating, the steam condenses, giving up its latent heat and changing from the vapour to the liquid phase. The condensate produced is either discharged to drain or collected for reuse. The latter option is preferred, as this condensate comprises high-quality water containing a significant amount of energy.
Simply put, boiler efficiency is a measure of the efficiency with which the energy added to the steam system (through fuels such as coal, gas, paraffin/kerosene, biomass etc.) is converted into energy that is usefully added to the boiler feed water to produce steam.
Power companies make it their business to generate electricity as cheaply as possible. It is not uncommon to find coal-fired boilers operating at efficiencies in excess of 90% at large power stations and at newer facilities, steam is generated at ever-higher pressures in a bid to maximise turbine efficiency.
