Abstract: A burner system comprising a central hearth tube defining a combustion chamber for a mixture of gas and air and made from thermomechanical ceramic, a tubular element comprising at its end located towards the gas outlet a radial restriction forming an axial and radial positioning stop for the hearth tube whereas the assembly of the latter to the other component parts of the burner is effected by a spring adapted to produce an axial pressure force under the impact of which the hearth tube is bearing upon said stop through a radial shoulder provided in its reduced portion, the burner providing a high velocity of outflow of the burnt gases.

Abstract: An inner tube for a radiant tube for recirculating burnt gases supplied by a burner, consisting of a plurality of axially aligned assembled tube sections arranged end to end whereas the assembling means consist each one of a sleeve coaxially surrounding the ends of said sections to be interconnected and the radially inner surface of which comprises in the middle of its length an annular collar projecting radially inwards and fitting between both tube sections to be connected together, the inner surface portions which are located on either side of the collar widening gradually towards the sleeve ends.