Abstract: Disclosed is an apparatus and method for preventing the formation of stagnate volumes and associated sludge deposition sites in the lower central regions of the steam generating fluid contained in a vertical-tube heat exchanger of a steam generator. The fluid in the steam generator is injected into the heat exchanger by diametrically-opposed flow vanes which direct the fluid in opposite directions near the central region of a heating tube support plate or tube sheet at the lower end of the heat exchanger. The fluid is injected closely adjacent and parallel to the tube sheet surface to thereby induce an initial rotational flow in the fluid, the rotational flow thus introduces horizontal and outwardly directed radial flow components into the vertically flowing fluid in the generator. The unique construction of the flow vanes induces a complex system of vertical, radial and rotational (horizontal) flow components into the steam generating fluid.