Rotary heat exchanger

Heat exchanger for the heating or cooling of a liquid, in particular a suspension having a high content of solid particles, comprising a container having an inlet and an outlet for said liquid positioned at opposite sides and opposite ends of said container, at least one substantially horizontal heat exchange unit being rotatably mounted in said container and comprising two end chambers communicating through a plurality of pipes arranged in a generally annular configuration, said container having below a horizontal plane through the rotational axis of said heat exchange unit a circular cylindrical shape to closely conform to said heat exchange unit, means for feeding a heat exchange fluid through said end chambers and said plurality of pipes, a central tube extending concentrically in relation to said rotational axis between said end chambers and being closed-off from them and from said container, said central tube having a diameter not less than 40% of the greatest distance between any two pipes of said heat exchange unit measured at right angles to said rotational axis, and said outlet from said container having a lower edge at a level lower than the uppermost portion of said central tube to maintain said uppermost portion above the free surface level of said liquid in said container.