NOVELTY - The process comprises charging a biomass feed and a heat carrier material to a mixing zone of a riser reactor above the location, where a lift gas is charged to the mixing zone for forming a mixture, converting the biomass feed in the mixture to form a reaction mixture comprising the heat carrier material and a product stream comprising oxygenated hydrocarbons, and charging a quench stream to the riser reactor through a quench stream conduit connected in fluid flow communication with the riser reactor at a location within an intermediate zone and an upper zone of the riser reactor.    USE - The process is useful for conversion of a biomass, which is useful as fuels for clean and controlled combustion in boilers and for diesel and stationary turbines, where the biomass material comprises lignocellulosic materials, forestry wastes such as wood chips and saw dust, agricultural waste such as straw, corn stover, sugar cane bagasse, municipal waste, yard waste, paper and card board, energy crops such as switch grass, coppice and eucalyptus, and aquatic materials such as algae.    ADVANTAGE - The process ensures rapid, economical and effective conversion of the biomass with high productivity and without robbing condensation.    DETAILED DESCRIPTION - The process comprises charging a biomass feed and a heat carrier material to a mixing zone of a riser reactor above the location, where a lift gas is charged to the mixing zone for forming a mixture, converting the biomass feed in the mixture to form a reaction mixture comprising the heat carrier material and a product stream comprising oxygenated hydrocarbons, charging a quench stream to the riser reactor through a quench stream conduit connected in fluid flow communication with the riser reactor at a location within an intermediate zone and an upper zone of the riser reactor for lowering the temperature of the reaction mixture, and separating the product stream from the heat carrier material in a disengager that is connected in fluid flow communication with the upper zone of the riser reactor. The intermediate zone is located above the mixing zone. The upper zone is located above the intermediate zone. The temperature of the reaction mixture is 450-575 degrees C. The temperature of the reaction mixture is lowered by 20-60 degrees C by a first, second and third of the quench streams so that the reaction mixture is a quench temperature. The quench stream is introduced at an interface between the mixing zone and the intermediate zone. The temperature of the reaction mixture is lowered to the quench temperature through the introduction of the quench streams in the intermediate zone and the upper zone. The quench stream comprises a fluid consisting of water, steam and dissolved organics. The water and steam are produced in the conversion process. Components of the quench stream react with organic components of the product stream to form stabilized organic compounds. The time between biomass feed conversion and the separation of the product stream from the heat carrier is less than 0.7 second. The heat carrier material/reaction product disengager comprises a cyclone that is closely coupled to the riser reactor. The heat carrier material comprises a material consisting of an inorganic inert material and/or an inorganic catalyst. The biomass feed comprises lignocellulose. An INDEPENDENT CLAIM is included for an apparatus for biomass conversion.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a riser reactor for fast pyrolysis.    Reactor (10)    Mixing zone (12)    Intermediate zone (13)    Upper zone (14)    Lift gas conduit (16)    Biomass feed conduit (18)    Heat carrier material conduit. (20)