NOVELTY - Fluidized bed reactor system comprises: at least two fluidized bed reactors comprising a first reactor (1) and a second reactor (2); a particle line for transporting fluidized bed particles from the first reactor into the second reactor; a particle line for transporting back fluidized bed particles into the first reactor; optionally a third reactor (20) which is designed as a stationary fluidized bed; and at least one connecting line (21) that transports only gas, for transferring a defined gas partial stream from the second reactor and/or the third reactor into the first reactor.    USE - The fluidized bed reactor system is useful for: generating gas; carrying out coal or biomass gasification or chemical looping reforming process (all claimed).    ADVANTAGE - The fluidized bed reactor system comprises the connecting line that transports only crude product gas without the solid into the first reactor, which completely avoids the costly purification of the crude product gas, and thus it is economic.    DETAILED DESCRIPTION - Fluidized bed reactor system comprises: at least two fluidized bed reactors comprising a first reactor (1) and a second reactor (2), which are respectively designed as a circulating fluidized bed and are provided with separate gas chambers for carrying out chemical reactions; a particle line for transporting fluidized bed particles from the first reactor into the second reactor; a particle line for transporting back fluidized bed particles into the first reactor; optionally a third reactor (20) which, as viewed in the direction of the circulating particle stream, is arranged between the second and the first reactor and is designed as a stationary fluidized bed; and at least one connecting line (21) that transports only gas, for transferring a defined gas partial stream from the second reactor and/or the third reactor into the first reactor. An INDEPENDENT CLAIM is also included for use of fluidized bed reactor system for generating gas.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the fluidized bed reactor system.    First reactor (1)    Second reactor (2)    Flow regulator (18)    Third reactor (20)    Connecting line (21)