Study of the Hot Top Performance with Various Heat Insulators

The paper contains a thermal performance calculation which proves that the basic items of heat loss include heat losses spent heating the hot top casing and lining. If thermal insulation is used, losses through the metal mirror do not exceed 3.5%. It is shown that in order to improve hot top efficiency it is required to minimize losses spent on heating the lining and the hot top casing; consequently, the amount of the heat transferred to the solidifying ingot can be increased. The assessment of the performance of the hot top with various heat insulators proves that the most efficient one is the untapered (straight) hot top insulated with the MKPB-340 inserts: in this case the quantity of heat transferred to the chill amounts to 70% of the overall value. An alteration of the hot top insulation type and geometry makes it possible to improve hot top thermal performance. As a result, the heat center of the solidifying ingot shifts to the hot top. Consequently, the shrinkage of solidifying steel is efficiently compensated, which decreases the physical and chemical heterogeneity of the billets produced and improves the ingot-to-product yield.