Advanced Technology Developments for Improving Blast Furnace Stave Life
Traditional failed stave cooling remediation implements the use of cigar or plate coolers, which are grouted in place through cutouts in the blast furnace shell and staves. Hatch has previously investigated the impact of traditional cigar coolers and concluded that the heat transfer between these supplementary coolers and the stave body is very low, offering minimal protection to the remaining stave copper.1 It was observed that the thermal conductivity of the grout used to establish contact between the cigar cooler and the stave is 20–100 times less than the highly conductive stave copper and, as a result, cigar coolers do not significantly affect heat removal from the damaged stave body. The stave is then insufficiently cooled and vulnerable to process upsets, which lead to high stave surface temperatures and the loss of protective accretions. Overheated stave bodies are observed to lose these protective accretions more rapidly, more frequently and require more time to redevelop the accretions when compared to colder stave bodies.2 The reintroduction of sufficient cooling aids in the development of stable accretions, which is a main objective for blast furnace operators.3 Finger coolers increase the rate of heat removal from the damaged stave body by replacing the thermally insulating grout with copper to copper pressure contact to produce a more conductive path of heat transfer. This results in dramatically lowered stave body temperatures and offers more protection against aggressive blast furnace conditions.