Abstract: The basic principle, technology and equipment improvements of recovering concentrated ethylene from FCC dry gas were introduced based on a case study. In the process improvements, the adjustment of product refining process, adding an arsenic removal step, adding separation and washing after MDEA treatment, altering regeneration gas in drying process, improving compression unit and setting a pre-distillation unit for ethylene pretreatment were reviewed. Equipment improvements including roots vacuum pump, electric heater, refrigeration dryer and semi-product gas compressor were discussed. Finally, factors affecting the long-term operation of unit, such as the properties of raw materials and liquid entrained, troubles in compressor system and vacuum system were analyzed and countermeasures were proposed.

Key words: FCC dry gas, concentrated ethylene, product refining, operation cycle