Abstract: Aiming at the problem of greatly shortened operation cycle of the ethane cracking furnace in an ethylene plant, this paper analyzed from the production process and it was found that the upstream ethane-rich gas contained impurities such as coke powder and amine liquid which were carried into the radiant coil. Due to the heavy components in the ethane-rich gas, coke was easily formed near the thermocouple at the furnace outlet, which resulted in inaccurate temperature indication. Mechanical analysis on the furnace tube indicates that the metal distribution on the inside surface of the radiant tube was abnormal. The mechanical performance test shows that the remaining service life of the radiant tube was only two years. It’s better to renew the radiant coil from the economic point of view, and the cracking furnace operates normally after the radiant coil has been renewed.

Key words: cracking furnace, furnace tube, operation cycle, mechanical properties