Abstract
Abstract Objective/Scope A localized tube rupture was observed in the convection section of Fired heater. To address this, improve Integrity and avoid Process Safety concerns, the existing convection section required replacement. This paper presents an alternate approach followed to reduce operating costs by enhancing the heater performance and efficiency while addressing high heat flux issue. Methods, Procedures, Process The new convection section was designed with an increased coil surface area to enhance the heat recovery and optimize heat flux. Fin materials were changed from original carbon steel to SS410 in high temperature zone to minimize fin burn-off issues. The challenges were phenomenal, as the heater was 40 years old and new convection section is twice heavy and size than existing. In order to overcome, systematic engineering approach was adopted, from sizing new convection section with optimum heat flux, Mechanical design with FEA to verify structure integrity and foundation adequacy for increased loads. As a step toward safeguarding the tube from similar future failure, tube skin thermocouples were installed in shield tubes to facilitate continuous monitoring. Results, Observations &Conclusions Analysis confirmed integrity of the heater with minimum modification on anchor bolt avoiding need major foundation and structural upgrade. Two furnaces have been upgraded with new convection section and continuous monitoring for period more than 1 year has confirmed performance with no tube failure ensuring 100% HSE. Post project implementation resulted in more heat recovery from flue gases due to increased. Flue gas temperature leaving convection section was reduced from 450°C to 220°C. Consequently, required fuel gas consumption was reduced considerably by 9031 MT per year for two heaters. In conclusion, similar reductions in fuel gas consumption can be achieved over the equipment's extended service life. The implementation has led to not only to increase in heater efficiency but in turn improved the heater duty for same burner capacity, there by supporting increase in plant throughput. Novel/Additive Information Conventional approach of replacing tube with improved metallurgy would have ensured process safety and structural integrity. However, the synchronized and pre-emptive engineering approach has yielded multiple benefits for the rest of the heater as well plant operational life. This also led to improved efficiency and Optimum Energy Conservation and save operating cost up to almost 1.1Million USD/year. Even a leak can lead us to peak if the opportunity is harvested in right way.
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