Improvement of No.1 RH Lower Vessel Campaign Life In Kakogawa Works

摘要

In order to satisfy a request for upgrading steel quality, No.3RH degasser was newly installed at Kakogawa works. After the start of No.3RH operation, the number of heats per day in the existing No.lRH degasser was decreased with an increase in the ratio of high-quality steel which requires long treatment time. With such a great change in service conditions, the campaign life of the No.lRH lower vessel decreased because of the unusual wear of the throat brick. In order to reveal the mechanism of this unusual wear, a stress analysis model of the RH lower vessel refractories was produced and stress analysis was carried out. It was found by means of this analysis that there exists high stress at the problem part of the throat bricks caused by the lack of expansion allowance of the bottom bricks. In order to satisfy the expansion allowance and reduce the stress, the lining of the bottom bricks was improved by using flexible board, and deformation of the bottom shell was controlled. With these improvements, wear of the problem parts decreased remarkably and sudden shut down by troubles has reduced. This paper describes these improvements made on the No.lRH degasser refractories based on stress analysis.