Gas-diffusion plate for fluidized bed apparatus

A fluidized bed reactor including a diffusion plate, said plate having a plurality of ports therethrough to provide for a plurality of flows of gas through said ports from one side of said plate to the other side thereof, wherein each of said ports comprises a threaded hole, the crests of said threads being truncated, threaded means individual to each of said ports rotatably engaged with a respective one of the threaded holes for axial adjustment within the individual port to define with the respective threaded hole an adjustable helical path for said flow of gas through said plate, the threaded means defining, with the surface of said other side of said plate, passage means to discharge the gaseous flow from each of the ports in a laterally, outwardly-directed path, said threaded means comprises a plurality of machine screws, one individual to each port and each having a head and shank and a lock washer received over the shank, said washer having a plurality of circumferentially spaced resilient tangs to adjustably position and secure said head in spaced relation with the said surface of said other side of said plate to define a plurality of channels beneath said head for gaseous flow in a plurality of radially and outwardly directed, substantially horizontal, gaseous streams across said surface.