Abstract: An apparatus for heat treatment of food products, in the form of a product bed consisting of solid particles, includes a container with a perforated bottom for the product bed. Gas is adapted to be supplied to the product bed in the container of this apparatus generally from below upwards through the perforated bottom at such a velocity that the product bed will form a fluidized bed. The gas, which is caused to circulate in the apparatus by means of a fan and to flow through the container as well as through a heat exchanger, is adapted to pulsate through the product bed in the container. According to the invention the apparatus is provided with a conduit passing by the container and being situated before the container with the perforated bottom, as counted in the flow direction, said conduit being provided with a rotatable damper which is adapted during its rotation to raise and lower the pressure under the perforated bottom for the pulsation of the gas through the product bed.

Abstract: Arrangement in a freezing plant, comprising a combination of a conventional freezer and a precool unit. The arrangement is connected between the freezer and the precool unit in such a way that the amount of air in the freezing plant is maintained substantially constant without any reaction with the ambient atmosphere.