Aiming at the local stress concentration problem at the large‑section rectangular inlet of the double‑inlet decoking drums with a diameter of 3 400 mm used in a 1.2 million tons per year ethylene cracking unit，the finite element calculation model of the decoking tank cylinder and the large‑sized double tangential inlet nozzle was established by using the Ansys software.The stress distribution of the large‑size tangential rectangular inlet pipe was obtained under various scenarios of rib thickness and spacing.The analysis primarily investigates the effect of rib thickness and spacing on the stress at the connection between the decoking drums and the tangential inlet pipe.The results indicate that the optimized rib thickness is 32 mm，with a spacing of 280 mm.Upon applying the actual combined loads encountered in engineering applications to the dual tangential inlet drum and assessing its strength according to pressure vessel design standards under both design and operational conditions，it is confirmed that the strength of the optimized drum meets the required standards.The research results provide a reliable basis for the engineering application of dual tangential inlet coke cleaning tanks.

ethylene cracking plant  /  decoking drums  /  dual tangential inlet  /  ribbed plate  /  stress analysis