Plant for the heat treatment of pellets

The plant according to the invention for the heat treatment of pellets consists of a transport mechanism 1 for the introduction of the pellets. It also comprises the following parts, viewed in the material flow direction through the system and in the direction in which the transport mechanism 1 moves: drying chambers 2,3, a firing or combustion chamber 4 with an arrangement for the introduction of a gaseous fuel, a cooling chamber 5, and a system for the forced introduction of air into the chambers and for the removal of the combustion products from the pellet layer on the transport mechanism 1. The fuel inlet device of the combustion chamber 4 consists of a distribution grill 11 which is arranged in the lower part of the combustion chamber 4 and is separated from the transport mechanism 1 by a distance representing from about 1/10 to about 1/4 of the height of the combustion chamber 4. The distribution grill 11 is so mounted that it occupies at least 40% of the horizontal surface of the combustion chamber 4. This distribution grill is formed by pipes 12 with an orifice for the supply of the gaseous fuel and by water-cooled pipes 13 that lie below the pipes 12 in the parallel direction. These pipes ensure the radial flow of the mixture of gaseous fuel and air in the pellet layer when the combustion products are being expelled from the pellet layer lying on the transport mechanism 1.