Carousel furnace with a rotary hearth for firing bulk materials

Abstract

The design of an electric carousel furnace with a rotary hearth platform for firing bulk materials is presented. When developing a new design of the carousel furnace, a platform furnace with a movable hearth plate was adopted as a prototype, in which the movement of the fired material was ensured by tilting the hearth plate and its vibrations created by an eccentric drive. This is the most advanced furnace in terms of energy intensity, used mainly for firing vermiculite, providing the lowest energy intensity of its firing process (80‒82 MJ/m3). The developed carousel furnace is not more energy efficient, but it eliminates some serious disadvantages of the platform furnace. Due to its fundamentally new design, the hearth platform performs a rotational movement and vermiculite particles swell up so that their structural transformation into bulk grains is not accompanied by friction on the hearth surface, there are no jumps and collisions, there is no grain breakage and peeling, less dust-like fractions accompanying the process are formed. All this ensures the highest quality of the finished product. Since the grains do not break during firing, their average nominal diameter increases by more than 54 %, therefore, the productivity of the furnace increases. In the carousel furnace, heat losses associated with convective heat entrainment by heated air at an inclined position of the firing modules in platform furnaces are reduced. The new furnace works exclusively with the horizontal position of the hearth, so there is no temperature difference in the marginal zones of the hearth platform and, accordingly, there is no air draft. The carousel furnace has a higher reliability due to the complete elimination of dynamic loads from the oscillatory movements of the platform in the adopted prototype. The hearth platform performs a rotational movement, which, unlike vibrations, does not cause alternating loads, and the circular symmetry of the hearth platform provides good balancing of rotating masses. Ill. 5. Ref. 8.