Abstract:

 A new aluminum-containing superalloy furnace tube NH1949 was adopted for the cracking furnace F-0401 in the ethylene cracking unit of a petrochemical company, and the average operating cycle of the cracking furnace was extended from 55 days to more than 100 days. After seven operating cycles, the coking speed of furnace tube was accelerated, and the operating cycle was reduced to less than 40 days. The cause may be that the Al₂O₃ membrane on the inner wall of furnace tube peels off to some extent during cyclic use. Practices show that the operating cycle of cracking furnace can be restored to an average of 80 days by passivation of the furnace tube.

Key words: cracking furnace, aluminum-containing superalloy furnace tube, coking, furnace tube passivation