Abstract: Currently, major refineries generally enrich C₂ resources in refinery dry gas through oil absorption or PSA to form concentrated dry gas, which is then introduced into the ethylene separation system for distillation separation, thereby obtaining high-concentration ethylene products. However, during the separation process, a large amount of ethane in the concentrated dry gas continuously circulates in the ethylene separation system, increasing system load and causing significant additional energy consumption. Therefore, The effect of a new process for selective separation of concentrated dry gasand a conventional process without selective separation on the energy consumption of the ethylene separation system through simulation of the ethylene separation process was compared and analyzed. The results show that the new process, which selectively separated ethane-rich gas directly into the ethylene cracking furnace, results in a lower amount of ethane circulating within the ethylene separation system compared to the conventional process. This can reduce the input power of the deep-cold-separation unit, C₂-separation unit, and C₃-separation unit by 19.52%, 32.26% and 35.21%, respectively, but at the cost of increasing the input power of the quench unit and compression unit. Comprehensive calculations of the power consumption of each equipment and the overall process operation indicate that, compared to the conventional process, the new process decreases electric, circulating water, and steam consumption by 18.67%, 15.17% and 22.52%, respectively.Overall, the new process reduces the energy consumption of the ethylene separation system by 22.41%.

Key words: concentrated dry gas, ethylene, selective separation, energy consumption, distillation