Abstract: An improved heat exchanger, applicable especially, but not exclusively, to a steam generator, preferably with straight or corrugated tubes (5) arranged in vertical concentric rows. The tubes (5) are maintained at certain axial levels thereof by concentric supporting systems, each of which consists of a zigzag circular strip (21) having alternate trapezoidal cells, and welded to a surrounding supporting strip (20). In the systems disposed at uncorrugated or "fixed" axial levels, the zigzag strip cells are shut off, after installation of the tubes (5), by a closing strip (22) to which is welded the supporting strip (20n) of the supporting system which is adjacent along the radial direction of the cylindrical casing (11), characterized in that at least some of the supporting systems (20, 21 . . . 20n, 21n) are independent of the supporting systems in the radial direction and form groups of supporting systems, and in that radial arms (14, 14', 14n) are provided for retaining said independent supporting systems.

Abstract: A heat exchanger comprising an outer heavy structure in the form of an outer cylindrical shell fixed at its upper end to an annular intake head and an annular outlet head for one of the fluids, of which the outer bases are perforated, and an inner lightweight structure subsequently mounted in the heavy structure and formed by an annular nest of tubes inserted and welded at their ends into the perforations in said bases and arranged in the form of concentric layers forming a large central passage which is accessible for installation of the tubes, beginning with the peripheral layer adjacent the outer shell, the concentric layers of tubes being held in several transverse planes by discs formed by concentric rows of rings arranged between these layers and joined together by connecting elements, a wide central shaft subsequently being fixed for internally defining the annular exchange chamber, wherein the discs by which the tubes are held in position and which are formed by the concentric rings are in some cases,

Abstract: A heat exchanger wherein the heat-exchanging structure comprises a light-weight assembly of undulated tubes in the form of an annular bundle located between a heavy cylindrical outer shell and a frangible central shaft, the ends of the tubes being fitted in drilled inlet and outlet heads fixed at the ends of the outer shell and the tubes being supported within the outer shell by co-axial hoops and radial braces.