Abstract: An evaporator comprises a plurality of substantially parallel plates mounted for rotation about a common axis and in which provision is made for a condensible vapor to flow across a first face of each of said plates and for a liquid, at least a portion of which is to be evaporated, to flow across the second face of each of said plate, which plates are arranged to be rotatable at such a mean acceleration, measured in a radial direction with respect to said axis of rotation, greater than the acceleration due to gravity, said first face of each of said plates has a surface designed to discourage formation of a continuous liquid film thereon. The evaporator may be used to concentrate solutions, e.g. of depleted brine or aqueous caustic soda.

Abstract: In a centrifugal mass transfer device comprising a rotary annular permeable element, annular plates are mounted adjacent the radially inner or outer face of the permeable element and gaseous or liquid material flowing from the permeable element across one surface of the annular plates is cooled or heated by a heat exchange fluid on the opposite surface of the plates. In this way condensed or vaporized material is returned to the permeable element.

Abstract: In a centrifugal device for contacting a liquid with a gas or with a second liquid, high rates of mass transfer are achieved by carrying out the contacting on a rotating plate whose surface is capable of creating perturbations in liquid flowing across it.