Abstract: A heat exchanger for use in exchanging heat between corrosive or electrolc fluids has wetted components which are comprised of corrosion and erosion resistant materials. The use of corrosion and erosion resistant tube sheets, shell, and tubes permits the heat exchanger to operate at high flow rates to produce turbulent flow through the inlet tube sheet and tubes, thereby optimizing transfer efficiency between a corrosive fluid in the tubes and the regenerated fluid pumped through the shell.In order to eliminate problems of temperature gradient and vibrations at the area where the tubes are joined to the inlet tube sheet, the shell is comprised of an inner and outer shell section to form annular flow diverting chambers therebetween. The inner shell section of each chamber is apertured so that flow is diffused over the entire surface, thereby avoiding direct impingement of fluid over the tubes.