A heat exchange device adapted for cooling a hot gas by means of a coolant liquid, comprising: a bundle of heat exchange tubes extending according to a longitudinal direction (X-X') between a first fixed baffle and a second floating baffle for passage of the hot gas to be cooled, a shell housing the bundle of tubes where the space between the shell and the bundle of tubes allows passage of the coolant liquid, where: - the shell is closed at one end by means of the first fixed baffle and comprises at the opposite end a chamber configured by means of an extension by means of a shell segment having a larger section closed with a third baffle, - a first coolant liquid inlet/outlet is located at a point of the shell on the side of the first baffle and a second coolant liquid inlet/outlet is established in a position of the shell segment having a larger section, wherein the second floating baffle has a manifold in fluid connection with the inlet of the heat exchange tubes, and said manifold is in turn in fluid connection with an inlet for the hot gas arranged in the third baffle, where this fluid connection is by means of an elastically deformable conduit at least according to longitudinal direction (X-X'), the second floating baffle forming together with the manifold an assembly which is housed in the extension formed by the shell segment having a larger section and spaced by a separation from said shell segment along the perimeter of said assembly (3, 9) to allow passage of the coolant liquid; and the position of the shell segment having a larger section where the second coolant liquid inlet/outlet is located is, according to longitudinal direction (X-X'), between the second floating baffle -manifold assembly and the third baffle, and characterized in that in the perimetral separation between the second floating baffle -manifold assembly and the shell segment having a larger section there is a deflector closing the separation space between said assembly (3, 9) and the shell segment having a larger section at least along a segment of said perimetral separation. a bundle of heat exchange tubes extending according to a longitudinal direction (X-X') between a first fixed baffle and a second floating baffle for passage of the hot gas to be cooled, a shell housing the bundle of tubes where the space between the shell and the bundle of tubes allows passage of the coolant liquid, where: - the shell is closed at one end by means of the first fixed baffle and comprises at the opposite end a chamber configured by means of an extension by means of a shell segment having a larger section closed with a third baffle, - a first coolant liquid inlet/outlet is located at a point of the shell on the side of the first baffle and a second coolant liquid inlet/outlet is established in a position of the shell segment having a larger section, - the shell is closed at one end by means of the first fixed baffle and comprises at the opposite end a chamber configured by means of an extension by means of a shell segment having a larger section closed with a third baffle, - a first coolant liquid inlet/outlet is located at a point of the shell on the side of the first baffle and a second coolant liquid inlet/outlet is established in a position of the shell segment having a larger section, wherein the second floating baffle has a manifold in fluid connection with the inlet of the heat exchange tubes, and said manifold is in turn in fluid connection with an inlet for the hot gas arranged in the third baffle, where this fluid connection is by means of an elastically deformable conduit at least according to longitudinal direction (X-X'), the second floating baffle forming together with the manifold an assembly which is housed in the extension formed by the shell segment having a larger section and spaced by a separation from said shell segment along the perimeter of said assembly (3, 9) to allow passage of the coolant liquid; and the position of the shell segment having a larger section where the second coolant liquid inlet/outlet is located is, according to longitudinal direction (X-X'), between the second floating baffle -manifold assembly and the third baffle, and characterized in that in the perimetral separation between the second floating baffle -manifold assembly and the shell segment having a larger section there is a deflector closing the separation space between said assembly (3, 9) and the shell segment having a larger section at least along a segment of said perimetral separation.