CRUDE FURNACE FLOOR CREEP ASSESSMENT AND REMAINING LIFE ASSESSMENT DUE TO HOT SPOTS

摘要

Fitness for Service (FFS) assessment and remaining life assessment of the furnace floor plates in a crude charge heater where hot spots up to 500°C have been observed during operation in 2018 was undertaken as apre assessment prior to the unit turnaround. The remaining life assessment results would provide the turnaround team with firm scope for repair in order to resintate the bottom plate and avoid discovery scope. Two Finite Element (FE) models were created to account for hotspot temperature conditions measured at November 2018 and June 2019. Each of these FE models involved successive loading conditions, so that the effects of each loading scenario could be investigated. The loading conditions were applied in steps, in the following order: 1.Gravity. 2.Temperature, modelling hotspot behaviour. 3.Creep, viscoelastic analysis. Utilising the FE models created for the two hotspot conditions, remaining life was calculated and suggested that the worst location for creep damage is near burner 2 (the maximum creep damage location of the November 2018 condition). Based on the assessment, the following recommendations are made: 1.Continue to observe and maintain temperatures below the creep temperature range (i.e. no additional hotspots are created and temperatures are not increasing). 2.Undertake creep testing from metal samples. 3. Re-inspect in 8 years at the same locations where metallographic replication was performed in September 2019.