COMBUSTION STEAM
Combustion Steam
Biomass combustion is a carbon-free process because the resulting CO2 has been previously captured by the plants being combusted. The amount of carbon dioxide (CO2) emitted during the burning process is typically 90% less than when burning fossil fuel. Wood fuel contains minimal amounts of sulfur and heavy metals. It is not a threat to acid rain pollution, and particulate emissions are controllable.
In a conventional biomass-fired combustion steam turbine, wood biomass is burned in a boiler to produce pressurized steam. The steam is expanded in a fully condensed turbine to generate electricity. These combustion methods will produce boiler efficiencies ranging from 65 to 75% with net plant efficiencies from 20 to 25%.
A second combustion design available for biomass is fluidized beds. In these designs wood biomass are injected into the combustion chamber through ports and burned in suspension. Air entering the boiler fluidizes a bed of hot, granular, inert material. The inert material heats the wood biomass quickly to ignition temperature, stores the thermal energy, and provides the appropriate residence time for full combustion.