Retrofit of sour water networks in oil refineries: A case study

A case study is presented of the retrofit of a sour water network in a petroleum refinery that generates 581,000 m3/yr of sour water. Flowrates and contaminant levels of ammonia and hydrogen sulfide were traced for all major water streams in the sour water network. By grouping some process units, a reuse scheme was found that only generates 280,000 m3/yr of sour water, saving 83% of freshwater and 52% in energy and CO2 emissions associated with pumping and the heat requirement to scrub out the sour components. Additionally, it was found that the remaining water, after treatment in the sour water stripper, could be reused elsewhere in the plant, if cyanide ions were eliminated. This case study has provided the foundation for further plant studies to validate the water profile of the proposed scheme.