Methodology to Estimate Remaining Blast Furnace Service Life
Accurate prediction of the blast furnace service life is essential to manage a steel plant’s short and long-term production and investment plans. Understanding service life allows reline planning, design engineering, and procurement of equipment and materials to be planned at the optimum time, neither too early, nor too late. To understand remaining life, the first step is to accurately determine the condition of the furnace proper and its ancillary equipment. A detailed review of significant furnace events, all historical process information, cooling systems issues, interim outage measurements, and completion of stave and/or refractory NDT measurements will lead to an accurate estimation of the ‘as is’ blast furnace condition. From this, the remaining life before a reline can be estimated. The service life estimate defines the priority issues on which to build a campaign extension strategy. A systematic methodology developed by Hatch to understand and forecast blast furnace service is described in this paper. Examples of blast furnace service life assessments will be discussed.
A proper assessment will also identify critical life limiting issues with the furnace, and be used to develop a campaign life extension strategy. For multi-furnace plants and companies, blast furnace service life assessments can prioritize which furnaces receive capital investment. In addition, a service life assessment that describes the state of the furnace can be provided to potential buyers during the sale of a steel plant.
Reline timing is generally determined by the first major area of the blast furnace to reach the end of its service life, mandating a significant downtime period to repair and/or replace that area of the furnace. While some areas of the blast furnace will have significant remaining life and will not require much attention, all areas of the furnace need to be assessed for remaining life at that point in time to ensure uninterrupted operations moving forward.