Advanced Technology Developments for Improving Blast Furnace Stave Life
Premature failure of copper staves is often the cause for an interim blast furnace repair at great cost to the blast furnace owner. Three important failure modes are: i) Cracking at the welded pipe connections; ii) local failure due to low cooling density as a result of poor cooling channel layout; and iii) wear on the hot face as a result of abrasion and erosion. Failures from these mechanisms lead to water leakages and the subsequent need to shut down cooling channels. The increase in stave temperatures caused by disabled cooling channels accelerates the rate of continuing damage. By reintroducing sufficient cooling to a damaged stave body affected by isolated water channels, operators can extend the life of these copper staves and the life of the blast furnace. The conventional approach to implement this type of repair is the installation of cigar or plate coolers. This paper presents a comparison of the thermal performance of cigar coolers against newly-developed finger cooler technology. The comparison includes experimental test work and conjugate heat transfer (CHT) analysis carried out using computational fluid dynamics (CFD) simulations. The comparison shows that under typical furnace excursion conditions, a stave fitted with finger coolers will limit temperature increase to less than half that of a stave fitted with a cigar cooler.