Abstract: This paper presents the principles of mechanical decoking and compares the advantages and disadvantages of mechanical decoking technology with the traditional steam-air decoking method. Taking the application of mechanical decoking technology in the vacuum furnace of the atmospheric and vacuum distillation (II) unit in one petrochemical company as an example, the paper expatiates onthe operation steps of mechanical decoking. Flow and pressure tests are carried out on all lines of the furnace tubes during the decoking process of this vacuum furnace. And the results show that after mechanical decoking, the average decrease in radiation temperature at the fire box top of the vacuum furnace is 58.3 ℃; the average decrease in surface temperature of the furnace tube is 10.3 ℃; the average decrease in feed pressure of the branch of the furnace tube is 0.20 MPa, and the fuel gas consumption (standard state) is decreased by 333 m3/h.The above results indicate that mechanical decoking is effective and it eliminates the bottleneck of the vacuum furnace operation. This can ensure the long-period safe and stable operation of the vacuum furnace.

Key words: atmospheric and vacuum distillation unit, vacuum furnace, mechanical decoking