NOVELTY - Preparing torrefied biomass fuel, comprises: extracting moisture from relatively wet biomass fuel in dryer to produce relatively dry biomass fuel; extracting all remaining moisture from relatively dry biomass fuel using steam at 482 degrees C (900 degrees F); conveying dried biomass fuel downward; torrefying dried biomass fuel to produce torrefied biomass fuel and torrefaction gases; venting gaseous mixture of steam and torrefaction gases to heat exchanger; heating gaseous mixture; and using heated gaseous mixture to support extraction of remaining moisture and torrefaction of dried biomass fuel.    USE - The process is useful for preparing torrefied biomass fuel (claimed).    ADVANTAGE - The process utilizes torrefaction system, which has ability to minimize the external fuel, supplemental natural gas and biomass, hence economical and environmental friendly.    DETAILED DESCRIPTION - Preparing a torrefied biomass fuel, comprises: extracting moisture from a relatively wet biomass fuel in a dryer to produce a relatively dry biomass fuel; extracting all remaining moisture from the relatively dry biomass fuel using steam at 482 degrees C (900 degrees F) to produce a dried biomass fuel; conveying the dried biomass fuel downward using gravity for subsequent processing; torrefying the dried biomass fuel to produce the torrefied biomass fuel and torrefaction gases; venting a gaseous mixture of the steam and the torrefaction gases to a heat exchanger; heating the gaseous mixture via heat exchange with a flue gas; and using the heated gaseous mixture to support the extraction of the remaining moisture from the relatively dry biomass and the torrefaction of the dried biomass fuel. An INDEPENDENT CLAIM is also included for a torrefaction system (100) comprising: a dryer configured to dry a relatively wet biomass fuel and provide a relatively dry biomass fuel; a torrefaction reactor comprising an upper chamber configured to remove all moisture from the relatively dry biomass fuel in an environment containing steam at 482 degrees C (900 degrees F), and a lower chamber configured to torrefy dried biomass produced by the upper chamber at 250-300 degrees C (482-572 degrees F); a combustion unit configured to combust a portion of a gaseous mixture of steam and torrefaction gases vented by the torrefaction reactor to produce a flue gas; and a heat exchanger configured to exchange heat from the flue gas to the gaseous mixture to provide a heated gaseous mixture for provision to the torrefaction reactor.    DESCRIPTION OF DRAWING(S) - The figure shows schematic representation of torrefaction system.    Input bin (1)    Airlock (2)    Dryer (3)    Prue-sized biomass (31)    Torrefaction system (100)