Simulation On The Decoking Of Radiation Section Coils Of Gas Thermal Cracking Furnace In Yanshan Petro-chemical Co.

Formation and shape of coke in coils of thermal cracking furnace, and advances in technologies of coking inhibitor, especially in decoking were reviewed in this paper. Because of the complexity of decoking few papers can be searched, therefore it is difficult to evaluate reasonability of the decoking program and give a scientific and rational suggestion for novel thermal cracking furnaces.Based on the abroad and domestic researches on decoking, a mathematic model had been established for simulation of decoking of Radiation Section Coils in gas thermal cracking furnace in Yanshan Petro-chemical Corporation. By using of the outside temperature profile of coils in actual operation condition and a given profile of coke thickness, the simulation results,include the changes of temperatures, coke thickness, COx, air and steam along axle of coil, as well as the effects of components of decoking gases, were obtained. A coincide between actual and simulated results was approached.By comparison and analysis of original, advanced and B decoking programs on end criteria of decoking and ratio of air to steam by simulation, it was found that:1) COX concentration at exit less than 0.5%, a criterion widely used in industry, may be far away from the total decoking;2) decoking can be benefited from increase the ratio of air to steam, KTI SMK gas cracking furnace in Yanshan petrochemical corporation had enough room for improving decoking in decrease of decoking time;3) B decoking program used in Yanshan Petrochemical Corporation was not suitable to KTI SMK gas cracking furnace, and original decoking program had better performance than that of B decoking program.