A finned tube rotary combustor for a municipal solid waste incinerator having a plurality of finned tubes disposed in a circular array so that the fins of adjacent tubes register, but are separate and form a gap for combustion air to pass from a divided windbox into the rotary combustor, the finned tubes being connected at each end to a ring header and at intermediate locations by channel shaped circumferential bands that have an outer peripheral surface that is utilized as the running surface for windbox radial seals and has legs with scalloped distal margins fitted and welded to the outer periphery of the finned tube array.