Embodiments of an obstructing member and methods for its use in a fluidized bed reactor are disclosed. The obstructing member comprises a plurality of receiving members, each receiving member comprising a tubular wall defining a passageway dimensioned to receive an internal reactor component, and a plurality of connecting elements connecting the receiving members, wherein the obstructing member occupies from 15-60% of a horizontal cross-section of a reaction chamber of the fluidized bed reactor.