Protected coils for a steam generator

摘要

In a steam generator for recovering heat in a hot fluidized bed of solid particles, wherein generally horizontally oriented coils of the steam generator make a 180 degrees U-bend, the U-bend portion of the coils are protected from overheating by installing an open top insulating box around the U-bend portion of the coil. In use solid particles from the circulating fluidized bed accumulate in the insulating box thus providing a non-moving layer of solid particles surrounding the U-bend which thermally insulates the U-bend portion of the coil from the higher temperature encountered in the moving fluidized bed.