Heat exchanger (100, 200) for cooling contaminated fluids and which are subjected to variable thermal load, by means of heat transfer to a receiving liquid and/or vapor fluid, said heat exchanger comprising a tube bundle consisting of a plurality of independent tubes (1), two plenums (9, 10, 109, 110), plates (12, 13, 112, 113), and characterized in that said independent tubes (1) comprise an inner tube (2, 102) in which the contaminated gas flows, and an outer tube (3, 103) being said inner tube (2, 102) and outer tube (3, 103) coaxial and where between the outer surface (2, 102) of the inner tube (2, 102) and the inner surface (31, 103) of the outer tube (3, 103) is defined an annular passage G in which flows the receiving fluid and in that said inner tube (2, 102) is welded to the plate (12, 112) in a gas inlet section, while a gas outlet section is guided in a corresponding hole of the plate (13, 113), so that the inner tube (2, 102) expansion in an axial direction is not constrained.

A compliant heating system includes a dynamic component including a heat exchanger; a pressure vessel shell encompassing at least a portion of the heat exchanger; and a compressive seal expansion that connects the dynamic component and the pressure vessel shell.