Abstract: For the sterilization of liquids (43) containing harmful microorganisms, or for the conditioning of mixtures of substances, a process and a heat exchanger (1) in the form of a tubular heat exchanger are used. The tube bundle (3) between the intake flange (2) and the outlet flange (4) is comprised of a number of tubes (18, 20) that are equal in length and that possess a narrow flow area and thin walls. These tubes, characterized as capillary tubes, are connected via distribution canals (15, 16) that are equal in length and similar in cross-section, to the central tube (12, 13) in the intake flange and in the outlet flange (2, 4). This causes the residence time distribution in the heat exchanger (1) to be held within very narrow limits, and causes the medium to be heated within fractions of a second to, for example, 140° C. or more, or less. This ensures a sterilization with the best possible preservation of thermolabile components, such as vitamins and proteins.

Abstract: A gas dispersion stirrer comprises a rotatable hollow shaft and at least one circular hollow stirring member disposed thereon wherein the cavity in the stirring member communicates with the hollow shaft. The stirring member has aeration apertures disposed in an outer peripheral portion thereof. The stirring member has flow-inducing blades for radially directing the liquid from the hollow shaft toward the aeration apertures. The gas dispersion stirrer effectively aerates liquids and achieves an improvement in mass transfer.

Abstract: The separation of different components of a fluid, e.g. of He, H.sub.2, O.sub.2, or the like from gaseous mixtures, separation of saturated and unsaturated hydrocarbon, water separation from organic mixtures, waste water purification etc., is effected by passing the treated fluid over a row of permeation cells each formed by a container subdivided, by a wall more readily permeable by one component of the fluid, into an inlet chamber and a permeate chamber. The respective chambers are arranged in series directed opposite to each other and the respective products are withdrawn at the respective ends of the series. A part of the product of the permeate chamber series is fed back into the inlet chamber series. Preferably, the delivery of untreated fluid into the inlet chamber series is effected at a point selected such as to obtain the smallest possible difference in the concentration of a respective component in the incoming untreated fluid and in the fluid being circulated through the system.