Abstract: A new wet oxidation treatment process of spent caustic waste water from a million-ton ethylene cracking plant was independently developed by SINOPEC, the technology consists of integrated heat exchange system, wet oxidation reaction system, two-phase decompression and separation system. The technology adopted the self-developed full mixed flow reactor, developed a separate gas distributor to enhance gas-liquid mass transfer in wet oxidation reaction. The effluent S2-concentration and COD of the industrial treatment unit for spent caustic waste water were less than 1 mg/L and 1 200 mg/L,respectively, which were superior to that of similar systems using foreign technology. The successful industrial application of this technology has realized the localization of sulfur-containing spent caustic waste water treatment technology and equipment in ethylene plant with capacity over 1 Mt/a, breaking the long-term monopoly position of foreign technology in this field.

Key words: ethylene plant, spent caustic, sulfide, wet oxidation