Heat-treatment installation for food products

A heat-treatment installation having a vertical midplane parallel to an insertion direction and comprising:

• a plurality of transport lines extending parallel to the insertion direction one above the other between an upstream zone and a downstream zone,
• at least one tray having, on either side of the vertical midplane, two wheels and a latch.
• a downstream lift in the downstream zone and an upstream lift in the upstream zone wherein each lift is arranged to move at least one tray from a lower transport line to another upper transport line,
• for each pair of a lower transport line and an upper transport line:
• on either side of the vertical midplane, a lower rail (108a) and an upper rail extending parallel to the insertion direction between the upstream zone and the downstream zone and on which the wheels of the trays travel, and
• on either side of the vertical midplane, an endless transmission belt (110) where each transmission belt carries a plurality of counter-latches and has a lower length arranged so that the counter-latches carried by said lower length cooperate with the latches of the trays travelling on the lower transport line and an upper length arranged so that the counter-latches carried by said upper length cooperate with the latches of the trays travelling on the upper transport line, where each transmission belt is disposed to the outside with respect to the wheels, and
• drive means arranged to drive each transmission belt,
• where, at the downstream lift, each upper rail has a recess in which a gate is disposed arranged to open when a tray is transported from the lower rail above the upper rail and to close again when the wheels of said tray are above the upper rail and where, at the upstream lift (106b), each lower rail has a recess in which a gate is disposed arranged to open when a tray is transported from an upper rail of the underlying pair, above the lower rail, and to close again when the wheels of said tray are above the lower rail.