Cause analysis and countermeasures for refinery sewage water stripping unit scaling

Because serious scaling phenomenon occurred on the reboiler and tray of the stripping column of 1 200×10³ t/a sewage water stripping unit in PetroChina Urumqi Petrochemical Company, the handling capacity decreased gradually from 175 t/h to below 140 t/h in less than a year, and purifying water quality appeared fluctuating. Scaling leads to temperature and pressure differences of tube condensed water between the inlet and outlet of the reboiler decreased, the amount of stripping steam could not be improved, ammonia and nitrogen in sulfur-bearing wastewater could not be effectively separated, which seriously affected the purification sewage quality. The measures about oil removal, filtration, injection of alkali and so on were adopted to effectively extend operating cycle of the equipment.