Heat exchanger, and in particular a steam generator having a convex bottom

A heat exchanger, in particular a steam generator comprising a generally cylindrical outer casing having an axis constituting the axis of the heat exchanger that is in a vertical disposition when the heat exchanger is in service, a bundle of tubes having straight portions that are parallel to one another and to the axis of the heat exchanger inside the outer casing, at least one tube plate having through holes, each having secured therein one end of a tube of the bundle, the tube plate being assembled to one end of the outer casing, at least one water chamber having a wall that is circularly symmetrical about the axis of the heat exchanger fixed to the tube plate at a bottom portion of the heat exchanger, at least one opening passing through the wall of the water chamber in a position that is laterally offset from the axis of the heat exchanger, the wall of the water chamber having an inside surface with a central portion situated around the axis of the heat exchanger constituting the inside surface of a solid bottom of the heat exchanger, the heat exchanger being in the in-service position of the heat exchanger with its axis vertical, at least one central point of the solid bottom surface of the heat exchanger disposed substantially on the axis of the heat exchanger and constituting the highest level relative to a set of points constituting the inside surface of the bottom of the heat exchanger, and the set of points constituting the inside surface of the bottom being situated above a conical surface having an apex point at the highest level of the inside surface of the bottom, an axis that is parallel to the axis of the heat exchanger, and a half-angle at the apex of about 80°.