Abstract:

This paper introduces the abnormal operation of the caustic wash tower and spent caustic oxidation system in the megaton ethylene plant at PetroChina Dushanzi Petrochemical Company, and analyzes the causes of the problems. In view of the main reasons, some specific measures were put forward and implemented. The cracking gas compressor was briefly stopped to open the interstage tanks. During the inspection, it was found that the root cause of the polymer produced in caustic wash tower was the serious blockage of the demister in separation tank at the entrance of caustic wash tower, which resulted in lower demister efficiency and eventually led to the entrainment of heavy components into the caustic wash tower to produce polymer. The replacement of demister of interstage tank fundamentally solved the problems such as the abnormal operation of caustic wash tower and the off-spec saline wastewater.

Key words: caustic wash tower, polymer, interstage tank, demister