Abstract: Based on studying the reaction characteristics of delayed coking and coking mechanism in furnace tubes, a technical revamping of the coking furnace of a 1.6 Mt/a delayed coking unit was carried out in order to control the cracking severity of feedstock leaving furnace, a software simulating process happened inside and outside of the furnace tube was adopted. Several novel technical measures and patents were involved in the revamping, as well as operating parameters optimization to enhance the heat provided for coking reactions by furnace and improve product distributions. The simulation results post to furnace revamping showed that the cracking severity of feedstock leaving furnace was deepened and the heat provided for coking reactions was enhanced significantly. Commercial running results showed that by adopting deep cracking technology in coking furnace, the processing capacity of the furnace increased and reached 1.85—1.90 Mt/a; the external surface temperature of furnace tube was about 80 ℃ lower than that of prior to revamping, and the operation period after coke burning was prolonged from 9-month to more than 15-month. After revamping, although the carbon residue in feed was higher, the coke yield/coke yield coefficient decreased and the liquid yield increased with good economic benefit, which indicated that this delayed coking unit could meet the requirements of processing inferior feedstock with high processing capacity and improved product distributions.

Key words: delayed coking, coking furnace, coking mechanism, cracking depth