Abstract: A circulating fluidized bed reactor comprising a top zone surrounded by walls provided with heat exchange tubes, the heat exchange tubes being interconnected by fins, and a bottom zone provided with a fluidization grid, a primary air injection device beneath the grid, a secondary air injection device above the grid, and a fuel injection device, the walls surrounding the bottom zone being provided with heat exchange tubes. The walls of the zones are provided with vertical heat exchange panels referred to as "extensions" that extend perpendicularly to the walls of the zones, that are made up of tubes inside the reactor, that are of horizontal width lying in the range 150 mm to 500 mm, and that are spaced apart from one another via a distance lying in the range 1.5 times to 4 times their width, the width being defined as the distance between the inside faces of the fins of the walls and the most distant generator lines of the most distant tubes of the extensions.

Abstract: A heat recovery method is disclosed suitable for combined gas turbine/steam turbine cycles including at the exhaust of a gas turbine a waste heat boiler in which water is first treated in a degassing unit connected to a first evaporator and comprising a certain number of heat exchangers. The boiler uses an ultrasupercritical steam cycle with four pressure levels with subcritical fluid intermediate evaporator stages.