Abstract: A floor which comprises a plurality of structural elements (10) of elongated parallelepiped shape with their longitudinal axis disposed horizontally. The structural elements are disposed adjacent to each other to form a flat horizontal structure supported by two opposing vertical walls (23) and 24) of the kiln. Each structural element (10) comprises two internal beams (11) positioned to the axis of the element and a plurality of blocks (12) of thermally insulating material, each being provided with two through holes (13) by which they are mounted along the internal beams (11). The blocks (12) are slidable along the internal beams (11); means also being provided for acting on the ends of the row of said blocks (12) to compress the row in an axial direction, thereby pressing the blocks together. The internal beams (11) are stressed only partially by the weight of the blocks (12), which can therefore have a greater specific gravity or thickness to increase the insulating effect of the floor.

Abstract: The nozzle comprises an axial chamber (23) provided in a first part (21) and into which the fuel gas is fed, and a chamber (24) which surrounds the chamber (23) and into which air is fed; the two chambers (23) and (24) are separated from the combustion chamber (4) by a front plate (5) in which three series of apertures are provided, namely a series of peripheral apertures (31) arranged to pass secondary air with a velocity having an axial and tangential component, a second series of apertures (32) disposed on a more inner circumference and arranged to pass primary air and also having an axial and possibly also tangential component, and a third series of more central apertures arranged to pass gas; by virtue of said apertures the burner thermal output is adjustable to the extent of enabling it to be varied within a very wide range of values.