NOVELTY - Drying system comprises a supply unit (110) having a mill (112) for milling spent culture medium, a drying unit (120) installed with a stirrer (124) in a drying chamber that dries while moving to stir the spent culture medium in a milling condition supplied from the supply unit, and forms the axis of rotation with a steam discharge pipe of the stirrer, a steam supply unit (130) for supplying high temperature steam supplied from a steam boiler that supplies dry steam to the steam discharge pipe of the drying unit, and supplying good quality dry steam to a heat steam generator for re-heating.    USE - The device is useful for production of agricultural by-products into pellets for fuel (claimed).    ADVANTAGE - The device can achieve pelletization for fuel by efficiently drying the spent culture medium generated after mushroom cultivation and by supplying good quality dry steam.    DETAILED DESCRIPTION - Drying system comprises a supply unit (110) having a mill (112) for milling spent culture medium, a drying unit (120) installed with a stirrer (124) in the longitudinal direction in the interior of a drying chamber that dries while moving to stir the spent culture medium in a milling condition supplied from the supply unit, and forms the axis of rotation with a steam discharge pipe of the stirrer, a steam supply unit (130) for supplying high temperature steam supplied from a steam boiler that supplies dry steam to the steam discharge pipe of the drying unit, and supplying good quality dry steam to a heat steam generator for re-heating, a discharge unit for storing the spent culture medium dried from the drying unit in a silo, and a pellet forming unit equipped with a molding machine for pelletizing to compress the dried spent culture medium supplied from the silo of the discharge unit.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of the drying system for production of agricultural by-products into pellets for fuel.    Supply unit (110)    Mill (112)    Drying unit (120)    Stirrer (124)    Steam supply unit (130)