Abstract: The designed service life of the furnace tubes in recycle hydrogen furnace in high-pressure hydrocracking unit is generally 100,000 hours. However, due to different working conditions, the replacement cycle of the furnace tubes may differ greatly from the designed service life. The furnace tubes in recycle hydrogen furnace in the high-pressure hydrogenation unit of certain petrochemical company has been running for a total of 140,000 hours. In this paper, the remaining service life of the furnace tubes is evaluated through on-site testing, chemical composition analysis and mechanical property test of the furnace tube samples, and then reasonable operation indexes were set and scientific arrangement of furnace tube replacement time was determined. In addition, guidance was presented for the safe operation of the unit in the future.

Key words: hydrocracking, recycle hydrogen, furnace tube, service life assessment