In a steam generator having a steam generator chamber into which heating elements are installed, a guide casing surrounds the elements and has an open bottom and a top cover plate. A series of steam separators are provided above the top cover plate and are completely encircled by an annular overflow plate arranged on the top cover plate. The overflow plate has a brim which is located above the water outlets of the steam separators and it also contains a plurality of holes that allow only about half of the return water to flow off.

Centrifugal separating apparatus comprising a concentric inner and outer housing enclosing a swirling chamber through which a steam-water mixture is directed to separate the water from the steam. The inner housing encloses a first set of vanes that impart a rotary movement to the steam-water mixture accompanied by a centrifugal action sufficient to separate water from the steam and move it outward through perforations in the inner housing. A second set of inclined vanes in the space between the inner and outer housing members serve to swirl the water and remove residual steam therefrom before it is recirculated.

A modular drying unit for a steam generator, having identical dryer elements arranged partly as a polygonal crown within the envelope of the generator and partly as a star within that crown. The dryers constitute in trios triangular cells the inner space of which is divided by a partition permitting isolation of the dryers with respect to one another, as well as guidance of the steam at the intake and outlet ends of the dryers. This type of unit is particularly suitable for generators with natural circulation, notably for a nuclear reactor.

A vertical shell-and-tube steam generator (10) which has a plurality of U-shaped tubes (60,62) through which the heating fluid flows, vaporizing fluid flowing on the outside of the tubes. A plurality of separators (26) are located above the tubes to remove liquid from the generated vapor. Orifices are located in some of the separator inlets (22) located above the hot leg region (60) of the U-tubes reducing the problem of overloading of these separators (26) by accomplishing a more uniform flow distribution of vapor from the areas above both the hot (60) and cold (62) legs of the U-tubes.

A device for trapping migrating bodies in nuclear power station steam generators or boilers is provided to prevent them from jamming between the generator tubes. The device, in the form of a grating or grid, is placed above a horizontal plate to which are fixed the upper ends of the pipes containing cyclone separators. It defines passages, whose largest dimensions are smaller than the minimum distance separating the tubes.